fill-1km. . ' II?” ~ J. I ll OVERDUE FINES: 25¢ per dqy per item RETURNING LIBRARY MATERIALS: N‘— Place in book return to ream charge from circulation recon 051013 NOV C‘- ’% 2.013 EFFECTS OF LIGHT AND TEMPERATURE ON PHYSIOLOGICAL AND MORPHOLOGICAL RESPONSES IN HYBRID GERANIUM AND MARIGOLD By Allan Munro Armitage A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1980 ABSTRACT EFFECTS OF LIGHT AND TEMPERATURE 0N PHYSIOLOGICAL AND MORPHOLOGICAL RESPONSES IN HYBRID GERANIUM AND MARIGOLD By Allan Munro Armitage Time to visible flower bud (<0.5 cm diameter) in hybrid geraniums was negatively correlated to light intensity as measured by quantum flux density (QFD) in the 400-700 nm range at a given temperature. Time required from visible bud to flower anthesis was negatively correlated with temperature while light had little effect. Leaf thickness, number of palisade layers, and specific leaf weight each were negatively correlated with temperature. Specific leaf weight was positively correlated with QFD. Net photosynthetic rate (PN) ranged from 5-38 mg 2 C0 dm- hr.l for temperatures of 10-37OC and Optimum PN was obtained 2 at 20-320C. The Q10 for respiration for mature hybrid geranium leaves was approximately 2.2. Flowering was accelerated with high temperature (32-350C) and high light (350-800 uE m-Zs-l) treatments applied for 9 days to 3-5 week old plants, however peduncle length and flower number were decreased. .Flowering time, dry weight, total leaf area, and vegetative height of marigolds based on QFD (50-600 uE m-zs-l), and day and night tempera- ture (lo-32°C) were determined through response surface techniques. Predicted total flowering time ranged from 20-70 days and was tempera- ture dependent, however time to visible bud was light dependent at high QFD (400-600 uE m-zs-l) and low night temperatures (lo-15°C) but was temperature dependent at all levels of QFD at 26°C night temperature. Time from visible bud to flower ranged from 12-30 days and was ii Allan Munro Armitage temperature dependent at 10°C night temperature but light dependent at low levels of QFD (50-300 uE m-zs-l). Dry weight ranged from 0.1-2.1 g and maximum dry weight occurred at high QFD (400-600 uE m-Zs-l), high day temperature (22-300C) and low night temperature (lo-15°C). Vegeta- tive height was greatest (14 cm) at high day temperature (30°C) and low night temperature (lo-15°C) while maximum leaf surface area (400 cm2) occurred only at 10°C night temperature and high day temperature (25-30°c>. Total foliar anthocyanin was negatively correlated to cumulative temperature and QFD. Conditions for maximum chlorOphyll (7.0 mg dm—Z) 23-1) and low day temperature (lo-15°C) were high QFD (500-600 uE m- and lO-lSOC night temperature but at 26°C night temperature high QFD and high day temperature (ZS-30°C) were necessary for maximum chlorOphyll production. There was no correlation either between anthocyanin and chlorophyll content or between foliar phosphorus or potassium and anthocyanin in marigold leaves. iii ACKNOWLEDGEMENTS My appreciation and thanks to my advisor, Dr. W.H. Carlson for allowing me the Opportunity and freedom to become involved in many aspects of floriculture while at Michigan State University. Thanks are also due the other members of my committee, Drs. H.P. Rasmussen, J.A. Flore, C.E. Cress, and A. Rotz for their comments and guidance. Gratefully acknowledged are the valuable suggestions made by Dr. R.D. Heins and Mr. V. Shull. My heartfelt gratitude to my wife Susan for the many sacrifices she had to make while giving me her unqualified support and also to my children, Laura and Heather for their belief in their father. iv Guidance Committee: The journal-article format was adopted for this dissertation in accordance with departmental and university requirements. Sections I-III were prepared and styled for publication in the Journal g£_the American Society g£_Horticultural Science. Section IV was prepared and styled for publication in HortScience. TABLE OF CONTENTS Page LIST OF TABLES OOOOOOOOOOOOOOOOOOOOOIOOOIOIOIOOOOOOOOOOOO Viii LIST OF FIGURES OOOIOOOOOOOOOOOOOOOOIOOOOOOOOOIOOOOOOOOOO x INTRODUCTION OOOOOOOOOOOOOOOIOOOOOOOOOOOO0.0.00.00.00.00. 1 SECTION I THE EFFECT OF TEMPERATURE AND QUANTUM FLUX DENSITY ON THE MORPHOLOGY, PHYSIOLOGY, AND FLOWERING OF HYBRID GERANIUMS 00......OCCOOOOOOOCOOOOOOCOOOOO0.00.00.00.00... 3 Introduction .......................................... 3 Materials and Methods ................................. 4 Results and Discussion ................................ 6 Conclusion ............................................ 8 Literature Cited OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO 10 SECTION II DETERMINATION OF FLOWERING TIME AND VEGETATIVE HABIT OF TAGETES PATULA THROUGH RESPONSE SURFACE TECHNIQUES....... 25 Introduction .......................................... 25 Materials and Methods ................................. 27 Results and Discussion ................................ 28 Conclusions ........................................... 31 Literature Cited OOCOOOOOOOOOOOOOOOOOOOOOOOOOO0.00...O. 33 SECTION III THE EFFECT OF QUANTUM FLUX DENSITY, DAY AND NIGHT TEMPERA-, TURE AND PHOSPHORUS AND POTASSIUM STATUS 0N ANTHOCYANIN AND CHLOROPHYLL CONTENT IN MARIGOLD LEAVES............... 48 IntrOdUCtion OOOOOOOCCOCOOOOOOOOOOOOOOOOOOOOOOCOOOOOCOO 48 Materials and MathOds COO...OOOOOOOOCOOOOOOOOOOO0.00... 50 Resu1ts and DiSCUSSion OOOOOOOOOOOOOOOOOOOOO0.00.0.0... 52 CODClUSionS OCOCOOOOOOOOOOOOOOOOOOOOOOOOOOOOO0.0.0.0... 53 Literature Cited OOOOOOOOOOOOOOOOOOOOOOOO0.00.00.00.00. 55 vi TABLE OF CONTENTS - continued SECTION IV Page FLOWERING POTENTIAL IN HYBRID GERANIUMS AS A RESULT OF “RIJY HEAT AND LIGHT TREATMENT 0.000000000000000.IOOOOOOOOOOOO 65 Introduction .............................................. 65 Materials and Methods ..................................... 66 Results and Discussion .................................... 67 Conclusion ................................................ 69 Literature Cited .0...OOOOOOOOOOOOOOOOOOOOOOOO00.00.0000... 7O vii LIST OF TABLES Table SECTION I The effect of quantum flux density on the flowering of hybrid geranium 'Sooner Red' ........................ The effect of temperature on the number of flowers per inflorescence at two different quantum flux denSitieS OOOOOOOOOCOOOOOOOOOO0......OOOOCOOOOOOOOOOOOOO The effect of temperature on light compensation and light saturation of hybrid geranium 'Sooner Red' ....... Percent of variation (R2) of PN at various temperatures accounted for by two functions of quantum flux density.. The effect of leaf temperature on dark respiration on hybrid geranium 'Sooner Red' ........................... SECTION II Actual and coded values for treatment combinations used incomp031tede51gn OOOOOOOOOOOOOOOOOOOOOO....00... Experimental values obtained for treatment combinations Of comPOSj-te deSign O...OOOOOOOIOOOOOOOOOOOOO0.0.0.0.... Regression coefficients and significance levels for flowering responses in Marigold 'Petite Yellow' ........ Optima for total flowering time and total leaf area at various levels of QFD and night temperature .... Regression coefficients and significance levels for vegetative responses in Marigold 'Petite Yellow' ....... The effect of quantum flux density, and day and night temperature on the rate of dry weight accumula- tion Of MarigOId 'Petite Yellow' .QOOOOOOOOOOCOOOOCOOOOO SECTION III Treatment combinations of day and night tempera- tures and quantum flux density ......................... viii Page 13 14 15 16 17 35 36 37 38 39 40 59 LIST OF TABLES - continued Table Page 2. The effect of temperature on foliar anthocyanin and chlorophyll content in 'Petite Yellow' marigold ..... 60 3. Total chlorophyll, total anthocyanin, phosphorus and potassium levels in 'Petite Yellow' marigold leaves 0......0..OCOOOOOOOCOOOOOOIOOCOCOOOOOOCOOOOOOOOOOO 61 SECTION IV 1. The effect of four weeks of constant temperature treatment on 10 day old hybrid geranium 'Sooner Red' .... 72 2. The effect of temperature-light combinations and plant age on growth and flowering of hybrid geranium 'Sooner Red' OOOOOOOOOOCOOIOOOOOO000......OOOOOOOOOOOOOOO 73 3. The duration effect of temperature-light treatments on flowering and height of 5 week hybrid geranium 'Sooner Red' COO...OOOOIOOOOOCOOOOIDOCOOOOOOOOOOOOOOOOOO. 74 ix LIST OF FIGURES Figure SECTION I The effect of temperature on the number of days from visible bud to flower anthesis in hybrid geranium 'Sooner Red' ........................... The effect of temperature on the flower diameter of hybrid geranium 'Sooner Red' ............... The effect of temperature on leaf thickness of hybrid geranium 'Sooner Red' ........................ The effect of temperature on leaf structure of hybrid geranium 'Sooner Red' ........................ The effect of quantum flux density on the specific leaf weight of hybrid geranium 'Sooner Red' ... The effect of temperature on the specific leaf weight of hybrid geranium 'Sooner Red' ................. The effect of temperature on net photosynthesis (PN) (mg 002 dm'zhr‘l) of hybrid geranium 'Sooner Red' ...... SECTION II A 15 point central composite design for response surface techniques. X1, X2, and X3 are QFD, day temperature, and night temperature respectively. Numbers refer to coded values ........................................... The effect of quantum flux density, and day and night temperature on the time to reach visible bud stage ..... The effect of quantum flux density and day and night temperature on the time from visible bud to flower antheSiS ......OOOOOOOO......OOOOOOOOOOOOCCO0.00.0000... The effect of quantum flux density and day and night temperature on total days to flower .................... The effect of quantum flux density and day and night temperature on dry weight at time of flower anthesis ... Page 18 19 20 21 22 23 24 41 42 43 44 45 LIST OF FIGURES - continued Figure Page 6. The effect of quantum flux density and day and night temperature on the vegetative height at time to flower antheSiS 00.0.0.0.........OOOCOOOOOOOOOOOO 46 7. The effect of quantum flux density and day and night temperature on total leaf surface area at time Of flower antheSiS 0000000000000000000000000000.0000 47 SECTION III 1. The effect of cumulative temperature on total anthocyanin (Total Acy) in leaves of marigold 'Petite YellW' .0.........OCOOIIO0.000.000.0000.00...... 62 2. Effect of day temperature and quantum flux density at various night temperatures on the total anthocyanin content in leaves of marigold 'Petite Yellow' ........... 63 3. Effect of day temperature and quantum flux density at various night temperatures on the total chlorophyll content in leaves of marigold 'Petite Yellow' ........... 64 xi INTRODUCTION The greenhouse environment is more amenable to environmental control than any other facet of horticulture. Night and day temperature may be routinely set by growers and incoming light may be decreased through shading practices or increased by supplemental light when necessary. Sophisticated equipment exists in greenhouses today to allow for precise environmental control, however optimum light-temperature regimes for various plant processes may be different. The manipulation of light and temperature to control flowering and growth is a necessary part of a growing strategy if the greenhouse operator is to be efficient in growing of the plant as well as in the market—place. Light and temperature cannot be considered alone in dealing with plant responses. Their interaction results in changes in reproductive and mor- phological responses which will certainly affect the flowering and vegetative habit and in turn the overall appearance of the plant. Temperature and light play a major role in physiological responses such as flowering, growth and pigment formation in bedding plants and optimum light-temperature regimes may be predicted which will give optimum plant responses. Hybrid geraniums have recently become a stable part of the bedding plant industry and marigolds continue to occupy a significant portion of the bedding plant market. These plants were studied due to their popularity as well as the relative lack of physiological information available for these crops. The objectives of this research were (a) to investigate the effects of light and temperature on flowering, leaf structure, and physiological process in hybrid geraniums, (b) to attempt to accelerate flowering time in hybrid geraniums with heat and light treatments during the seedling stage and (c) to determine light and day-night temperature combinations to optimize reproductive and morphological processes in marigolds. Developing a better understanding of the effects of light-temperature interactions on floral crOps will aid in attaining a more efficient and knowledgeable floricultural industry. SECTION I THE EFFECT OF TEMPERATURE AND QUANTUM FLUX DENSITY ON THE MORPHOLOGY, PHYSIOLOGY, AND FLOWERING OF HYBRID GERANIUMS THE EFFECT OF TEMPERATURE AND QUANTUM FLUX DENSITY ON THE MORPHOLOGY, PHYSIOLOGY, AND FLOWERING OF HYBRID GERANIUMS A.M. Armitage, W.H. Carlson and J.A. Flore Department of Horticultural Science Michigan State University East Lansing, Michigan 48824 Additional Index Words: leaf thickness, leaf mesophyll, photosynthetic rate, Q10, specific leaf weight Abstract: Hybrid geraniums (Pelargonium x hortorum Bailey) 'Sooner Red' were grown at temperatures ranging from 10°C - 32°C and at various quantum flux densities. The time to visible bud stage ( J no.0 <.u-;..a.x NO OF PHLISRDE LRYERS HESOPHYLL THICKNESS/TOTHL THICKNESS 0.9 av 8 ..o Hmzwmxmficwm an. F I F AI‘ ND.O p ‘ .u... ..9.-..._ 8.... . 4 name 4mzwma=qeam .n. SLN (M cm" ) Figure 5. 22 R2-97 3-00 " y- .30+.03x 2000 " A j j j 1 C 1 4r . 0 20.0 4030 8030 30:0 OURNTUM FLUX DENSITY '(uE M.2 5-] ) 4 l I 100.0 The effect of quantum flux density on the specific leaf weight of hybrid geranium 'Sooner Red'. Broken lines represent 95% confidence limits of true regression line. Q 120.0 23 4 \ \ Y=6.I- .IOX 6.00 " °.' 5 5 g 4000 1 3 ..J (D 3000 1 2“050.0 : 10:0 ' 15:0 ' 2030 25.0 30.0 TENPERRTURE (C) Figure 6. The effect of temperature on the specific leaf weight of hybrid geranium 'Sooner Red'. Broken lines represent 95% confidence limits of true regression line. Figure 7. 2 -1 s ) on net The effect of quantum flux density (;E m- photosynthesis (PN) (mg CO2 dm-Zhr-l) of hybrid geranium 'Sooner Red' at various temperatures. 3) Effect of 100C constant temperature on PS b) Effect of 15-320C constant temperature on PX c) Effect of 37°C constant temperature on PS a) Z 0. ‘b) 2 IL e) Z 0. 24 10 C ‘ 1 a 2 0 ° ‘3’ o ‘ o 1.) g? 01 1 t : : : 400 000 1200 1000 15 TO 32 C 40.00 . U xx x 30.00 .. 0 x + x D m 4. B 0 ‘9 0 20-00 " S + 1.20m 3 o 150 10.00 1. a 01 2°C 8 + 25C .. & x :20 400 000 1200 1600 37 C 40.00 30.00 - 20.00‘ 0 0 db .0 oo 0 10.00 1 08 400 ' 000 1200 1000 OURNTUH FLUX DENSITY (at-’11") SECTION II DETERMINATION OF FLOWERING TIME AND VEGETATIVE HABIT OF TAGETES PATULA THROUGH RESPONSE SURFACE TECHNIQUES DETERMINATION OF FLOWERING TIME AND VEGETATIVE HABIT OF TAGETES PATULA THROUGH RESPONSE SURFACE TECHNIQUES A.M. Armitage, W.H. Carlson and C.E. Cress Department of Horticultural Science Michigan State University East Lansing, Michigan 48824 Additional Index Words: composite design, dry weight, leaf surface area, vegetative height Abstract: The prediction of flowering time, dry weight, total leaf area and vegetative height of Tagetes patula L, based on day temperature, night temperature and quantum flux density are demonstrated. High temperatures (30°C) decrease flower time regardless of QFD and greatest leaf surface area was caused by high QFD. As night temperatures increased, maximum leaf area occurred at lower day temperatures than those necessary for fastest flowering time. Response surface techniques for characterization of each response as well as the relative importance of each factor are discussed. The application of this technique to horticultural research is discussed. Environmental effects on flowering and growth of greenhouse crops have been studied extensively. Temperature (7,13,19,22,23), light (6,9,12) and their interaction (8,14,16,21,24) on flowering and/or growth of many crops have been reported, however little has been done with bedding plants. Research on environmental control of greenhouse crops has dealt with one or two factors but has not shown how a change in one factor may be compensated by a change in a second factor to maintain a desired response. In trying to elucidate environmental 25 26 conditions which produce a given response, experiments with factorial combination of treatments usually result in only one or two combinations which yield the desired response. A full complement of factorial combinations to test three factors at p levels results in p3 experiments which may be too costly or too time consuming, especially if each experiment is lengthy. Response surface techniques minimize the number of experimental treatments required to adequately cover a given range of factors (11,15,17) and often incorporate a composite design (2,3,4). Response surface experiments have been used in other fields (10,17,18) but have not received much attention in the plant sciences. If levels of each factor in a 3-factor composite design are coded, a 15 point central design in three factors would appear as in Figure 1. In our experiment, we wished to determine the effect of quantum flux density (QFD) in the 400—700 nm range, night temperature and day temperature on the flowering and growth of Tagetes patula, a dwarf french hybrid marigold. Specifically we determined all possible combinations of these three factors which would result in characteriza- tion of flowering time, growth (dry weight, total leaf surface area) and vegetative height. Recent work with hybrid geraniums (1,20) has shown that QFD and temperature affect different stages of flowering independently, therefore we determined if this was also true for marigolds. Tagetes species are long day, short day or day neutral plants (5), however Tagetes patula 'Petite Yellow' is day neutral with respect to flowering. It is a popular, widely grown bedding plant and served as the experimental plant. 27 Materials and Methods Seeds of Tagetes patula L. 'Petite Yellow' were germinated under mist in their growing containers and placed in growth chambers1 at appropriate treatment combinations (Table 1) approximately 10 days 2 1 after sowing. Temperatures fluctuated 12°C and QFD varied :10 uE m- s- and the photoperiod was 16 h light, 8 h dark. Plants were grown in an artificial peat lite medium and were fertilized with 20-20-20 water soluble fertilizer to provide 200 ppm N at each irrigation. Plants were leached as needed to prevent soluble salt accumulation. The 15 point composite design covered the surface of 10-320 in 5 levels for both day and night temperature and 50-600 uE m-zs-1 in four levels for QFD. The highest QFD level was not possible due to physical limitations of growth chambers used. In the treatment design (Fig. 1), the 8 vertices of the cube form a 3 variable, 2 level factorial. The ninth treatment is at the middle of the cube and was replicated 5 times to provide an inde- pendent measure of error. The remaining 6 treatments were placed at predetermined points :2 units along the three axes. The time to reach visible bud stage (<0.5 cm in diameter) was recorded and data for dry weight, vegetative height and total leaf surface area were gathered at flower anthesis. Regression coefficients were determined and isoquants of similar responses were drawn for each parameter recorded. In order to adequately describe the surface and contain linear, quadratic and interaction terms, a second order model in the form of A _ 2 2 2 y - bo + blx1 + b2x2 + b3x3 + bllxl + bzzx2 + b33x3 + bllex2 + b13xlx3 + b23x2x3 1Shere-Gillete, Marshall, MI 28 was selected where § is the measured response, x1, x2, x3 are the actual variables for QFD, day temperature (DT) and night temperature (NT) respectively and the b's are the regression coefficients. Results and Discussion The means of the experimental values for all treatment combina— tions are given in Table 2. High day temperatures of 32°C resulted in bud development, however many plants died before reaching anthesis. In both stages of flowering, as well as total time to flower, linear and/or quadratic terms of QFD were highly significant (Table 3). Day and night temperature, and their interaction, were significant in the visible bud to flower stage. This corresponds with results found with geraniums (1,20) and lilies (25) namely that temperature is highly correlated to flower development once initiation has occurred. Day temperature significantly affects the time to reach visible bud, although night temperature has little significance (Table 3). Surface response plots (Fig. 2 a-c) for time to reach visible bud indicate that at cold night temperatures (10°) minimal time is obtained at very high light levels over a small range of day temperatures. However as night temperature increased, a lower optimum (i.e., less time) occurred over a wide range of light but over small day temperature ranges (Fig. 2). When night temperatures are high, day temperatures appear to be the limiting factor. High day temperatures and high light cause increased PN which may compensate for increased respiration losses under high night temperatures. When night temperatures drop, light appears to be limiting for bud formation. Low night temperatures likely caused decreased metabolism and high light levels may have been necessary for more rapid growth and flowering. 29 Temperatures above 30°C resulted in death of the flower bud, therefore plots were truncated at that point. Visible bud to flower (Fig. 3 a-c) appear to be temperature dependent under cool night temperatures, however as night temperatures rise (Fig. 3c), the response becomes more light dependent with the response increasing with increasing QFD. This appears to be Opposite to the time to visible bud stage and reflects some independence from one another in the stages in marigold flowering. It also indicates that QFD is very important in marigolds for flower development under high (>26) night temperatures but not under cool temperatures. Minimum total days to flower (Fig. 4 a—c) is a combination of high light and high day temperatures regardless of night temperature. However, the Optimum response is lower (i.e., fewer days) with lower night temperatures compared with high temperatures. This confirms the work of many researchers (13,19) in that lower night temperatures enhanced flowering and growth of greenhouse crops compared with warm night temperatures. A summary of minimum flowering times under different light intensities and temperatures are given in Table 4. Growth. Vegetative parameters chosen were dry weight, total leaf surface area and vegetative height at flowering as overall appearance and plant "quality" are most dependent on these factors. A second order model of the same form used for flowering responses was calculated and the regression coefficients and their significances are shown in Table 5. In all growth responses, linear and/or quadratic trends of QFD and day temperature were highly significant. Day—night temperature interaction was highly significant in vegetative height and leaf surface area while QFD x NT was the only interaction with dry weight. Response 30 surface plots of dry weight (Fig. 5 a-c) indicate that maximum dry weight accumulation occurred with cool day temperatures and high light, regardless of night temperature. The lowest dry weight accumulation was under low light conditions. With marigolds, high light results in the highest dry weight even when night temperatures are high. The range of dry weight accumulation is narrower and the lowest dry weights do not occur at high night temperatures (Fig. 5c). These predictions show dry weight accumulation at flowering but not the rate of dry weight accumulation. Dry weight accumulation at flowering indicated that temperature is very important but the rate of dry weight increase appeared to be a function of QFD (Table 6). Maximum plant growth occurred during weeks 6 to 8 when growth under 150 uE mfzs-l, and week 4 when grown under 375 uE m-zs-1 except when day temperatures were extreme (10 or 32°). At these temperatures, maximum increase in growth under 375 uE m-Zs-1 was delayed until week 6. Maximum growth occurred at weeks 3 to 4 when plants were subjected to 600 uE m-Zs-l. The large 2 flush of growth at QFD's of 150 to 600 uE me 3.1 did not occur at zs_1 indicating expected slow growth under winter light 50 uE mf conditions. An optimum for vegetative height could not be assessed, however extremely tall plants would be unsuitable for shipping and excessively dwarfed plants would likely be unmarketable. High temperatures caused elongation of internodes of various species and result in tall plants. Response surface plots for vegetative height (Fig. 6 a-c) indicated that as day temperatures rise, height increases, regardless of night tempera- ture. High QFD (500-600 uE m-zs-l) and low QFD (260). Large total leaf area would be beneficial for more carbohydrate production as well as the aesthetics of the plant. Low night tempera- ture, coupled with low day temperature resulted in less surface area (Fig. 7 a-c), however the largest amount of leaf area occurred with cool night temperature (lo-15°) compared with higher night temperatures. At low night temperature, the smallest leaf area occurred over a wide range of light but as night temperature increased, the range of QFD became narrower for any one isoquant. The largest total leaf area at high night temperatures occurred at the highest QFD and mid range day temperatures. Higher day temperatures were necessary for high leaf area at lower night temperatures. Temperatures appear to play a major role in control of leaf surface area. Light affects carbohydrate production through PN and hormonal movement which controls cell division, elongation and growth. Temperature affects overall metabolism such as cell division and cell elongation and thus leaf expansion. Day temperatures necessary for maximum leaf area at given night temperatures and light levels were lower than those necessary for minimum flowering time (Table 4). The grower must make decisions based on the overall plant appearance as well as flowering time. The ability to predict growth and flowering responses would be of great importance to the floriculture industry. More control of the environment is possible in the greenhouse than in any other commercial facet of horticulture. Studies of this type can be used to develop answers to questions related to timing, appearance and yield of a greenhouse crap under a wide range of light and temperatures. Other factors could be included in the model such as humidity, soil temperatures, 32 C02, etc., however light and temperature are easily measured, and controlled and adequately describe the growth and flowering of this crop. Computer programs could be built around experimental data and optima for any crop predicted. Significant values of independent variables would allow growers to make more intelligent decisions when varying the environment to obtain desired flowering and growth. 10. 11. 12. 13. 14. 33 Literature Cited Armitage, A.M. and W.H. Carlson. 1980. The effect of temperature and quantum flux density on the morphology, physiology and flowering of hybrid geraniums. In review. Box, G.E.P. 1954. The exploration and exploitation of response surfaces: Some general considerations and examples. Biometrics 10: 16-60. and F.S. Hunter. 1957. Multifactor experimental designs for exploring response surfaces. Ann. Math. Stat. 28: and K.B. Wilson. 1951. On the experimental attain- ment of optimum conditions. Jour. Roy. Stat. Sco., Series B, XIII (l). Carlson, W.H. 1977. Marigold Timing. Grower Talks. Aug., p.5. Carpenter, W.J. and J.P. Nautiyal. 1969. Light intensity and air movement effects on leaf temperatures and growth of shade-requiring greenhouse plants. J, Amer. Soc. Hort. Sci. 94: 212-214. , E.N. Hansen, and W.H. Carlson. 1973. Medium temperatures effect on geranium and poinsettia root initiation and elongation. lg, Amer. Soc. Hort. Sci. 98: 64-66. Cathey, H.M. 1954. Chrysanthemum temperature study. B. Thermal modifications of photoperiods previous to and after flower bud initiation. Proc. Amer. Soc. Hort. Sci. 64: 492-498. Cathey, H.M. 1954. Chrysanthemum temperature study. C. The effect of night, day, and mean temperature upon the flowering of Chrysanthemum morifolium. Proc. Amer. Soc. Hort. Sci. 64: 499-502. Chandler, P.T. and R.G. Cragle. 1962. Investigation of calcium, phosphorus and vitamin D relationships on rate by multiple regression techniques. g, Nutrition 78: 1-30. Cocharan, W.G. and G.M. Cox. 1957. Experimental Design . John Wiley & Sons. New York. Duffet, W.E. 1970. Snapdragons in winter at 60°F. Ohio Flor. 3111 o 371: 6‘8. Furuta, K. and K.S. Nelson. 1953. The effect of high night temperatures on the development of chrysanthemum flower buds. Proc. Amer. Soc. Hort. Sci. 61: 548-550. Gaastra, P. 1959. Photosynthesis of crap plants as influenced by light, carbon dioxide, temperature and stomatal diffusion resistance. Meded. Landbouwhogeschool, Wageningen 59: 1-68. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 34 Gardiner, D.A., R.G. Cragle, and P.T. Chandler. 1967. The response surface method as a biological research tool. Tenn. Agric. Expt. Sta. Bul. 429: 25-40. Hackett, W.P. and J. Kister. 1974. Environmental factors affecting flowering in Pelargonium domesticum cultivars. lg, Amer. Soc. Hort. Sci. 99: 15-17. Hader, R.J., M.E. Harwood, D.D. Mason, and D.P. Moore. 1957. An investigation of some of the relationships of copper, iron, and molybedum in the growth and nutrition of lettuce: I. Experimental design and statistical methods for characterizing the response surface. Soil Sci. Soc. Amer. Proc. 21: 59-64. Hammer, P.A. and R.W. Langhans. 1976. Growth models for Helianthus annus L. and Zinnia elegans Jacq. ‘J, Amer. Soc. Hanan, J.J. 1959. Influence of day temperatures on growth and flowering of carnations. Proc. Amer. Soc. Hort. Sci. 74: 692-703. Heins, R.D. 1979. Influence of temperature on flower development of geranium (Sprinter Scarlet' from visible bud to flower. BPI News, Dec. p. 5. Litlere, B. and E. Stromme. 1975. The influence of temperature, day length and light intensity on flowering in Hydrangea macrophylla (Thunb.) ser. Acta Horticulturae 51: 285-298. Miller, R.O. 1960. Growth and flowering of snapdragons as affected by night temperatures adjusted in relation to light intensity. Proc. Amer. Soc. Hort. Sci. 75: 761-768. Smith, D.R. and R.W. Langhans. 1962. The influence of day and night temperatures on the growth and flowering of the Easter lily (Lilium longiflorum Thunb. var Croft). Proc. Amer. Soc. Hort. Sgi. 80: 593-598. Went, F.W. 1957. The experimental control of plant growth. Chronica Botanica Co., Waltham, Mass. 343pp. 35 Table 1. Actual and coded values for treatment combinations used in composite design. QFD Temperature (c) Coded Values (11E 111’2 Day Night QFD DT NT 1. 50 21 21 -2 O 0 2. 150 15 15 -l -1 -l 3. 150 15 26 -l -l l 4. 150 26 15 -l l -1 5. 150 26 26 -l 1 l 6. 375 21 21 O 0 0 7. 375 21 10 0 O -2 8. 375 21 32 0 O 2 9. 375 32 21 0 2 O 10. 375 10 21 O -2 0 11. 600 15 26 l -l l 12. 600 26 26 l l l 13. 600 15 15 l -1 -1 14. 600 26 15 1 l -1 36 Table 2. Experimental values1 obtained for treatment combinations of composite design. Days to Days Dry Vegetative Total Treatment visible from VB weight height leaf area QFD DT/NT bud to flower (g) (cm) (cm2) 1. 50 21/21 36.8 29.0 0.14 2.35 74.8 2. 150 15/15 33.8 31.7 0.28 2.25 107.8 3. 150 26/15 21.2 31.9 0.69 5.65 186.7 4. 150 26/15 22.3 28.5 0.80 7.55 233.0 5. 150 26/26 22.5 23.4 0.66 4.90 97.6 6. 375 21/21 17.0 27.0 1.23 6.41 285.9 7. 375 21/21 17.1 29.2 1.00 5.99 300.5 8. 375 21/21 17.9 27.4 1.05 6.42 280.6 9. 375 21/21 16.8 26.5 0.99 5.95 260.2 10. 375 21/21 18.5 27.1 1.23 6.92 305.4 11. 375 21/10 19.7 27.3 1.00 5.22 263.5 12. 375 21/32 16.5 25.8 1.40 6.45 338.0 13. 375 32/21 16.8 - - 13.85 - 14. 375 10/21 25.2 35.6 1.02 4.05 102.8 15. 600 15/26 16.8 23.1 1.02 4.00 187.1 16. 600 26/26 13.8 19.0 1.43 5.52 227.7 17. 600 15/15 27.5 23.1 1.62 3.71 174.4 18. 600 26/15 15.6 21.5 2.15 6.42 374.1 1Means of 60 observations 37 Hmowm w. wmmnmmmmoo nommmwomonm moo mwmoemwnmsom Hm¢D 000 Figure 4. The effect of quantum flux density and day and night temperature on total days to flower. Each isoquant differs by 5 days. (a) Night temperature 10°C (b) Night temperature 15°C (c) Night temperature 26°C DRY TEMPERRTURE (C) DRY TEHPERRTURE (C) DRY TENPERRTURE (C) 40.0 30.0 20.0 10.0 30.0 20.0 40.0 30.0 20.0 10-0 44 OURNTUH FLUX DENSITY ( usn‘zs'1 10 C 20 x o o ‘11:“ 90¢, Xxx), ++H~+++ ... 30 ‘ a Q, >°< xx x q» x . ”M “ o In "X ‘H *m a... . ‘ " | ‘ x T T ‘1'! 111 111111 50 __ I" M ~. . § .1- -’ | " K‘ W n ‘m . fi'fl_ I ’ulx; ._ | me x 60 ._ ”I" 70 0 ' 200 ' 400 ' 600 000 15 C 4)- . ~x x+*+ + El Mum 1— A ‘1?" “in: M...° “moo 40 x a C . h ‘ ‘ 1 1. g. Aha“. L - I xx . w “ - ' 11‘ \ “my: 111 50 up \ I F' . {HM ..‘.-II'. \~ I ‘qu.1 1- D- 'H ”TEE! 70 60 0 ' 200 ' 400 ' 000 ' 000 26 C v .. 5 Q o x x “1+ um magma, fi» 0’ x>< -* ' ‘ ‘2 “’9 x +++1+ ++ + 30 db ‘ . x ~ .\~. °° x x o i 0&9.» .. u% ‘A‘ We. 40 " H ‘H“ ..‘Na 5 ’& ”hi ‘.-hua '4. ‘ i ‘ 60 50 .L 0 I 200 ' 406 ' 000 j 000 (a) (b) (c) FIHUI‘C‘ 5 o The effect of quantum flux density and day and night temperature on dry weight at time of flower anthesis. Each isoquant differs by 0.3 g. (a) Night temperature 100C (h) Night temperature 150C (0) Night temperature 20°C 45 \I a ( 40.0 30.0 nu. mmnpamMm:MP 10.0 >¢D (b) no“ mxzkcmmmzwh ram (C) a u 0 3 no. uxnhcmmmzmh ram 600 -25-1 400 200 DURNTUH FLUX DENSITY ( uEm Figure 6. The effect of quantum flux density and day and night temperature on the vegetative height at time of flower anthesis. Each isoquant differs by 2 cm. (a) Night temperature 10 C (b) Night temperature 13 C (c) Night temperature 26 C DRY TEHPERRTURE (C) DRY TEMPERRTURE (C) DRY TENPERRTURE (C) 46 10 C 40.0 ‘ . . u . l4 ' w ‘ ‘ x . “ AA AA A 9 1° .. + + XX m 0“ . ‘. .x 5 xx x x x xx >8 20.0 «- 0mm ‘H 411» 41+ (9 H++++ .. hum El. 2 “mm mm 10.0 0 1 200 I 400 ' 000 ' 000 15 C 10.0 “ ,.. O t 14 )k ’0...‘ AA AA 0‘ " ++ xx X. o o M x 6 + 20.0 4- +++ Xx x" "x’wo‘ .1111 +++ 11- 0‘ fl+++ 2 0000 " l 2 0 ' 200 400 ' 000 ' 000 26 C 40.0 30,0 . 0.0 A. ‘ A A“ 0 x xx "00 o ”m . Q O” x 6 0 + m»: x" 20 0 - ‘3‘ o ‘ '0} + 4 11 .1. 10.0 1- 4* "‘ ’k 5 4 0 ' 200.00 400.00 ' 2110111.00 ' 000.00 QURNTUI‘I FLUX DENSITY ( uEm' s' ) (a) (b) (e) Figure 7. The effect of quantum flux density and day and night temperature on total leaf surface area at time of flower anthesis. Each isoquant differs by 50 cm2. (a) Night temperature 10°C (b) Night temperature 15°C (c) Night temperature 26°C DRY TEHPERRTURE (C) "\\‘\\\. . + ”in“. M. a a an 300 ‘M." ’“an:N"”‘°. .0000 (9%“! “+11. *1 ”00m x x 1000“ 200 0%” "llama; . + ++H+ 100 ”@0000 o o 9% 200 400 000 ' DRY TEHPERRTURE (C) DRY TENPERRTURE (C) A v 200 400 0020 . ounmun FLUX DENSITY 1 1w." J SECTION III THE EFFECT OF QUANTUM FLUX DENSITY, DAY AND NIGHT TEMPERATURE AND PHOSPHORUS AND POTASSIUM STATUS ON ANTHOCYANIN AND CHLOROPHYLL CONTENT IN MARIGOLD LEAVES THE EFFECT OF QUANTUM FLUX DENSITY, DAY AND NIGHT TEMPERATURE AND PHOSPHORUS AND POTASSIUM STATUS ON ANTHOCYANIN AND CHLOROPHYLL CONTENT IN MARIGOLD LEAVES A.M. Armitage and W.H. Carlson Department of Horticultural Science Michigan State University East Lansing, Michigan 48824 Additional Index Words: response surface Abstract: A temperature of 10°C resulted in the greatest synthesis of anthocyanins in marigold foliage regardless of whether cold was applied during the day or night. Response surface techniques were used to determine combinations of light and temperature which result in equal levels of anthocyanin and chlorophyll. Predicted responses indicate that as night temperature increased from 10 to 26°C, a wide range of quantum flux densities and day temperatures resulted in low anthocyanin content. Night temperature of 10°C and high day temperature resulted in the same chlorophyll content as 26°C night temperature and low day temperature if quantum flux density was low. No significant correlation was found between anthocyanin level and foliar phosphorus or potassium. The french marigold (Tagetes patula L.) is of major importance to the bedding plant industry and ranks second in volume sales in the United States and Canada (42). Although primarily known for its yellow- orange flowers, the foliage is important to the overall appearance of the plant. Anthocyanins in the leaves affect the hue of the plant and its marketability. The environment under which the plant is grown can have a marked affect on chlorOphyll and total anthocyanin content of the 48 49 foliage (4,25,27,32). The synthesis of anthocyanins appear to be related to increased light intensities (13,16,32), low temperatures (8,28,34), and the high irradiance response (HIR) mechanism (11,12). Carbohydrate metabolism may play a role (10,35,40), however Mancinelli 23 a1. (27) used photo- synthetic inhibitors and dismissed photosynthesis as an active partici- pant in anthocyanin synthesis. Anthocyanins in the leaves of plants such as copper beach and red cabbage do not inhibit photosynthesis indicating the continued presence and function of chlorophyll (37). Seedlings deprived of nitrogen, phosphorus, or potassium often show increased anthocyanin content in crops such as lettuce (45), and apple fruit (44). Tomatoes are very sensitive to phosphorus levels (22) and potassium deficiency has accelerated anthocyanin production in some craps (39,43). The relative effects of day versus night temperature on anthocyanin synthesis have been studied by Hanan (20) using red carnations. He found that decreased day temperature led to increased anthocyanin production while FreyAWyssling and Blank (16) found that red cabbage colored best at 30°C day compared with 10°C. Cool night temperatures were optimum in apple fruits (41) while average temperatures 2 days before sampling were found by Creasy 25 £1. (10) as the limiting factor in anthocyanin production in apples. Anthocyanins occur as glycosides of anthocyanins and are usually simple monosides of cyanidin in dicot leaves (21). Anthocyanins have been fully identified in 11 genera of plants of Compositae and cyanidin 3-glycoside (usually glucoside, galactoside, or arabinoside) is the most prevalent anthocyanin of the family (21). The interaction of chlorophyll and anthocyanin has received little attention in floriculture and its effect on crap 50 appearance but Reger (33) found that an induced chlorosis in apples resulted in enhanced anthocyanin production. This study investigates (i) the effect of temperature on total anthocyanin and chlorophyll content of the foliage, (ii) the inter- action of quantum flux density and temperature on total anthocyanin, (T Acy) and total chlorophyll (T Chl) and (iii) the correlation between phosphorus and potassium with T Acy in leaves. Materials and Methods Two separate experiments were conducted to study the environmental effects of T Acy and chlorophyll. Temperature: Plants of Tagetes patula L. cv. Petite Yellow were direct seeded in a 1:1 peat-vermiculite media and were placed in growth chambers 10 days after sowing. Cool white fluorescent lights provided 400 :10 uE m.”zs-1 at the following temperatures: 1: 21 day, 21 night; 2: 21 D, 21 N; 3: 21 D, 32 N; 4: 32 D, 21 N; 5: 10 D, 21 N. Temperatures fluctuated iZOC and photoperiod was 16 h light and 8 h dark. Plants were fertilized with water soluble fertilizer at 200 ppm of 20 N, 8.7 P, 16.7 K and leached every 7 days to prevent soluble salt buildup. All treatments were maintained for 3 weeks before plants were excised. Pigment analysis: Chlorophyll: Four leaf discs were immediately macerated after excision in 2 ml cold 80% acetone. Two 2 ml washes followed and the total sample was centrifuged at 5000 rpm (Sorvall, model RCZB, head $834). The supernatent was stored in the dark at 0°C while 2 m1 of solvent were added to the pellet and recentrifuged. The total supernatent was brought to a final volume of 8 ml and read on a Gilford 220 spectrophotometer at 51 645 nm (chl b) and 663 nm (chl a). Extraction and analysis was done under dim white light. Calculations for chlorophyll a, chlorOphyll b, and total chlorophyll were derived from equations of Arnon (3). Anthocyanin: A method adapted from Fuleki and Francis (17) was used for T Acy analysis. The following abbreviated procedure was used with 95% ethanol:l.5 N HCL (85:15) as the solvent: Three gm of leaf tissue and 40 ml solvent were macerated in a blender, washed twice with 10 ml solvent and centrifuged twice at 4500 rpm for 25 minutes. The supernatent was poured through #1 Whatman filter and washed 3 times with equal volumes of petroleum ether in a separatory funnel to eliminate masking by chlorophyll. The ethanol phase was washed 3 times with equal volumes of hexane to extract carotenoids and other polar pigments. The ethanol phase was diluted to an appr0priate volume and the wavelength of maximum absorbance was determined on a Beckman scanning spectrophoto- meter. One aliquot was adjusted to pH 1 (21) and another to pH 4.5 to eliminate breakdown products and precursors (18). The absorbance of T Acy was read at 532 nm and specific Acy equivalents were determined (29). T Acy were calculated using extinction coefficients for specific anthocyanins (l7). Light-Temperature Interaction: Fifteen environmental treatment combina- tions were arranged in a 3 factor central composite design (6) in 5 levels of day and night temperatures (lo-32°C) and 4 levels of quantum flux density (QFD) measured in the 400-700 nm range (Table l). A second order model was fitted for each pigment and response surface plots were drawn (2). All treatments were carried out in growth chambers similar to the previous experiment. Pigment and nutrient analysis were determined 21 days after placement in the chambers. Phosphorus and potassium levels in the foliage were determined by photoelectric spectrometry similar to 52 methods of Kenworthy (23). Results and Discussion Temperature: Temperature significantly affected T Acy, chlorophyll b, and total chlor0phyll, but not chlorophyll a (Table 2). A highly significant negative correlation between cumulative temperature (O/day) and T Acy indicated that total amount of heat (cold) regulates T Acy production regardless of whether the heat (cold) occurs during the day or night. We hypothesize that an increase in T Acy with cold temperature may be related to stress induced ethylene synthesis. Although we did not measure CZH4’ its production under stress likely activates the phenylalanine ammonia lyase enzyme (7,15), an integral part of the Acy biosynthetic pathway (11,38). It is possible to consider increased foliar Acy in marigolds as an example of chilling induced ethylene generated Acy synthesis. There appeared to be no strong correlation between T Acy and T Chl in the foliage (r=.55) indicating that T Acy does not appear to increase by competition for substrate with chlorophyll production confirming other work (14,27). Light-Temperature Interaction: Experimental data and regression coefficients were recorded for T Acy and T Chl for points on the composite design (Table 3). T Acy was temperature dependent and the lowest values for T Acy occurred at the highest day temperatures (Fig. 2). However the highest values of T Acy occurred at the upper QFD range regardless of night temperature. Acy synthesis is light mediated (21,16) and phytochrome appears to be the only pigment involved in its synthesis (5,26,31). Plants synthesize more Acy in the light compared with dark (21) and as light was increased to 600 uE m-zs-l, more T Acy was formed. It is unlikely that 600 uE m-zs-1 was 53 sufficient to trigger the HIR involved with T Acy synthesis and therefore light appears to be less important for Acy production compared with temperature in this study. Trends appeared to be the same for all night temperatures although as night temperatures rose, a wider range of QFD and day temperature cause the lowest response. Response plots of T Chl appear to be both light and temperature dependent (Fig. 3). Minimum levels of T Chl occurred only at 10 and 26°C nights. At 10°C nights, maximum T Chl occurred at high QFD and low day temperatures whereas at 26°C nights, warm day temperatures and high or low QFD resulted in the same effect. High T Chl occurred in wheat (30) at 15 or 28°C with high light, however high temperatures (32°C) in hybrid geranium resulted in solarization of chlorophyll (1). Other work with hybrid geraniums has shown that very high QFD (>1000 uE m-zs-l) resulted in less chlorophyll than at low light levels (36). We were not able to attain sufficiently high light levels to test those findings with marigolds. We found no significant correlation between T Acy in leaf tissue and phosphorus, potassium, or a combination of these nutrients (r=.26-.46). The data indicate that nutrient uptake was sufficient however under conditions beneficial to T Acy synthesis, utilization or translocation of these nutrients may have been reduced. The synthesis of Acy reported as a result of nutrient deficiencies may be more realistically explained on the basis of stress ethylene. Nutrient deficiency and low temperature may simply be secondary causes of anthocyanin synthesis. The practical ramifications of this work are significant as growers lower night temperatures to conserve fuel. Lower temperatures increase 54 anthocyanin levels which change the hue of the plant. Energy conserva- tion has resulted in an increase in polyethylene-type growing structures and there is less incident light reaching the plant compared with glass structures. This will cause lower chlorophyll levels regardless of temperature. 10. 11. 12. 13. 14. 55 Literature Cited Armitage, A.M., and W.H. Carlson. 1980. The effect of tempera— ture and quantum flux density on the morphology, physiology, and flowering of hybrid geraniums. '12 Review. , C.E. Cress. 1980. Optimization of flowering time and vegetative habit of Tagetes patula through response surface techniques. .In_Review. Arnon, D.I. 1949. Copper enzymes in isolated chloroplasts polyphenol oxidase in Beta vulgaris. Plant Physiol. 24: 1-15. Blank, F. 1947. The anthocyanin pigments of plants. Bot. Rev. 13: 241-317. Bothwick, H.A., S.B. Hendricks, M.J. Schneider, R.B. Taylorson, and V.K. Tools. 1969. The high energy light reaction controlling plant response and development. Proc. Nat. Acad. Sci. USA 64: 479- 486. Box, G.E.P. 1954. The exploitation and exploration of response surfaces. Some general considerations and examples. Biometrics 10: 16-60. Chalmers, D.J., and J.D. Faragher. 1977. Regulation of anthocyanin in apple skin. II. Involvement with ethylene. Austral. g, Plant Physiol. 4: 123-131. Creasy, L.L. 1968. The role of low temperature in anthocyanin synthesis in McIntosh apples. Proc. Amer. Soc. Hort. Sci. 93: 716-724. . 1968. The increase in phenylalanine ammonia-lyase in strawberry leaf discs and its correlation with flavenoid synthesis. Phytochemistry 7: 441-446. , E.C. Maxie, and C.O. Chichester. 1965. Anthocyanin in strawberry leaf discs. Phytochemistry 4: 517-521. Downs, R.J. and W.H. Siegleman. 1963. Photocontrol of anthocyanin synthesis in milo seedlings. Plant Physiol. 38: 25-30. Drumm, H. and H. Mohr. 1978. The mode of interaction between blue light receptor and phytochrome in anthocyanin formation of the soybean seedling. Photochem. Photobiol. 27: 241-248. Duke, 8.0. and W. Naylor. 1976. Light control of anthocyanin biosynthesis in Zea seedlings. Physiol. Plant. 37: 62-68. , S.B. Fox and A.W. Naylor. 1973. Photosynthetic independence of light induced anthocyanin formation in Zea seedlings. Plant Physiol. 57: 192-196. 15. l6. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 56 Faragner, J.D. and D.J. Chalmers. 1977. Regulation of antho- cyanin synthesis in apple skin. III. Involvement of phenylalanine ammonia-lyase. Austral. g, Plant Physiol. 4: 133-141. Frey-Wyssling, A., and F. Blank. 1943. Untersuchungen uber die physiologie de anthocyans in Reimblingen von Brassica oleracea L. var capitata L.f. rubra (L) Ber. Schweiz. Botan. Ges. 53: 550-578. Fuleki, T., and F.J. Francis. 1968. Quantitative methods for anthocyanins. I. Extraction and determination for total anthocyanin in cranberries. g, Food Sci. 33: 72-77. . 1968. Quantitative methods for antho- cyanins. II. Determination of total anthocyanin and degradative index for cranberry juice. ‘g, Food Sci. 33: 78-83. Goodwin, T.W. Chemistrygand Biochemistry of Plant Pigments. 1965. Academic Press, New York. Hanan, J.J. 1959. Influence of day temperatures on growth and flowering of carnations. Proc. Amer. Soc. Hort. Sci. 74: 692-703. Harborne, J.B. Comparative Biochemistry of the Flavenoids. 1967. Academic Press, New York. Hussy, G.L. 1963. Temperature and anthocyanins in tomato seedlings. Kenworthy, A.L. 1960. Photoelectric spectrometer analysis of plant materials. Report presented at annual ASHS meeting, Stillwater, OK. Ku, P.K., and A.L. Mancinelli. 1972. Photocontrol of anthocyanin synthesis. I. Action of short, prolonged, and intermittent irradiations on the formation of anthocyanins in cabbage, mustard, and turnip seedlings. Plant Physiol. 49: 212-217. Magness, J.R. 1928. Observations on color development in apples. Proc. Amer. Soc. Hort. Sci. 25: 289-292. Mancinelli, A.L., C.H. Yang, I. Rabino, and R.M. Kuzmanoff. 1977. Photocontrol of anthocyanin synthesis. V. Further evidence against the involvement of photosynthesis in HIR anthocyanin synthesis of young seedlings. Plant Physiol. 63: 841-846. , and L. Walsh. 1979. Photocontrol of anthocyanin synthesis. VII. Factors affecting the spectral sensitivity of anthocyanin synthesis in young seedlings. Plant Physiol. 63: 841-846. Marousky, F.J. 1968. Effects of temperature on anthocyanin content and color of poinsettia bracts. Proc. Amer. Soc. Hort. Sci. 92: 678-684. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 57 McLellan, M.R., and J.N. Cash. 1979. Application of anthocyanins as colorants for maraschino-type cherries. g, Food Sci. 44: 483-487. McWilliam, J.R. and A.W. Naylor. 1958. Temperature and plant adaptation. I. Interaction of temperature and light in the synthesis of chlorophyll in corn. Plant Physiol. 42: 1714-1715. Mohr, H. 1972. Lectures 22_Photomorphogenesis. Springer-Verlag, New York. 237 pp. Proctor, J.T.A. and L.L. Creasy. 1971. Effect of supplementary light on anthocyanin synthesis in McIntosh apples. g, Amer. Soc. Hort Sci. 96: 523-526. Reger, M.W. 1944. Thiocyanate induced chlorosis predisposes deve10pment of anthocyanin by exposing apple skin tissue to more blue-violet light. Proc. Amer. Soc. Hort. Sci. 45: 111-112. Rutland, R.B. 1968. The effect of temperature on the concentration of anthocyanin in pink flowers of Chrysanthemum morifolium Ram. cv. Orchid Queen. Proc. Amer. Soc. Hort. Sci. 93: 576-582. , and K. Walters-Seawright. 1973. Anthocyanin in flowers of Chrysanthemum morifolium Ram. during anthesis in relation to sugar content. g, Amer. Soc. Hort. Sci. 98: 74-77. Sams, C., A.M. Armitage, J. Flore, R. Miranda, and W.H. Carlson. 1980. Unpublished Results. Siegleman, H.W., and S.B. Hendricks. 1957.. Photocontrol of anthocyanin formation in turnip and red cabbage seedlings. Plant Physiol. 32: 393-398. Tan, S.C. 1979. Relationships and interactions between phenyl- alanine ammonia-lyase, phenylalanine ammonia-lyase inactivating system, and anthocyanin in apples. g, Amer. Soc. Hort. Sci. 104: Thimann, K.V., and Y.H. Edmondson. 1949. The biogenesis of anthocyanin. I. General nutritional conditions leading to anthocyanin formation. Arch. Biochem. Biophys. 22: 33-58. , and S.B. Radner. 1951. The biogenesis of anthocyanin. II. The role of sugars in anthocyanin formation. Arch. Biochem. Biophys. 34: 305-333. Uota, M. 1932. Temperature studies on the development of antho- cyanins in McIntosh apples. Proc. Amer. Soc. Hort. Sci. 59: 231-237. Voight, A.O. 1979. Bedding plant sellers market slackens. BPI News, March. 43. 44. 45. 58 Wall, M.E. 1939. The role of potassium in plants. I. Effect of various amounts of potassium on nitrogenous, carbohydrate, and mineral metabolism in the plant. Soil Sci. 47: 143-161. Weeks, W.D., F.W. Southwick, M. Drake, and J.E. Steckle. 1958. The effect of varying rates of nitrogen and potassium on the mineral composition of McIntosh foliage and fruit color. Proc. Amer. Soc. Hort. Sci. 71: 11-19. Woodman, R.M. 1939. Studies in the nutrition of vegetables. The effects of variation in the nitrogen supply on lettuce (var May King) in sand culture. Ann. Bot. 3: 649-656. 59 Table 1. Treatment combinations of day and night temperatures and quantum flux density.2 Treatment Quantum Flux Density Day Temperature Night Temperature (us {261) (C) (a) l 50 21 21 2 150 15 15 3 150 15 26 4 150 26 15 5 150 26 26 6 375 21 10 7 375 10 21 8 375 32 21 9 375 21 32 10 375 21 21 11 600 15 15 12 600 15 26 13 600 26 15 14 600 26 26 Z Treatments chosen according to (2). 60 Table 2. The effect of temperature on foliar anthocyanin and chlorophyll content in 'Petite Yellow' marigold. Temperature (C) Chlorophyll a Chlorophyll b Total Total1 _2 _2 ChlorOphyll Anthocyanin Day Night (mg dm ) (mg dm ) (mg dm’ ) (mg g'l) 10 21 3.08 a2 1.37 ab 4.45 ab 1.68 a 21 10 2.57 a 1.12 c 3.69 be 0.65 b 21 21 3.14 a 1.12 c 4.26 a 0.24 c 21 32 3.62 a 1.29 b 4.91 a 0.20 c 32 21 3.75 a 1.46 a 5.21 a 0.01 d leanidin 3-glycoside equivalents (max.k =532 nm) zMean separation in columns by HSD (.05) 61 Table 3. Total chlorophyll, total anthocyanin, phosphorus and potassium levels in 'Petite Yellow' marigold foliage. Treatment Total Total Phosphorus Potassium Chlorophyll Anthocyanin (mg din-2) (mg 3.1) (ppm) (ppm) 1 2.59 0.09 10537 4390 2 3.15 0.43 13108 4013 3 3.15 0.30 12133 5545 4 4.03 0.23 10032 4725 5 5.26 0.17 10160 4411 6 3.97 0.19 8790 3859 7 3.47 0.59 7654 2739 8 4.87 1.43 11034 4299 9 4.91 0.05 10011 4234 10 4.19 0.28 6953 2659 11 6.57 0.76 14290 4380 12 5.46 0.78 10701 4190 13 5.78 0.66 11232 5645 14 5.98 0.68 11276 4969 62 2 o 1.60 ‘. e R . 87 ,1 0 y=12.45-2.08(1n x) F- '1’ " = 1020 ’ ,- ea “ ‘ d 0080 ‘*' ‘ S h :1. e .— 0.40 4" 1r- 8 a 300.0 ' 406.0 606.0 ' 606.0 ' 706.0 ' 300.0 CUMULRTIVE DEGREES PER DRY Figure 1. The effect of cumulative temperature on total anthocyanin (Total Acy) content in leaves of marigold 'Petite Yellow'. ... o. e : . ....“ ... V " - ..-- - 5“»..- \I o. g E. 2 n. . .2 S .C 63 DRY TEHPERHTURE (C) DRY TEHPERRTURE (Cl A8 a 3 n pm n A V .99 3.0 80° w 80° 0.. ”00° C N909 v 0.0 ob ‘ —.~ 3... .. S... . to! In... to» __‘l ... o . 8m. . Sm 4. 8m .8 o 8.” 6m. 8m .8 255:: 2.5 8222 . 5-..; 252:... 1.5 3222 A 5.-..-. l 2 n E a n E 09.9. .9... a.» ,8... .. 00000000000“ 5 8... . 00000000000000...- .. c a.» 3.. A. S... . \. .... 4 023% 9.9 . 11:31.... ...-1.3.30. 8.88.8.8. r» 8.: : _ 8.: r filé‘ovn‘k‘l ... Lml . 3m . 3.“ J. .8. .8. a . n8. a 8% 0 2m 4. .8 25:2: 2.5 8.5.3 . E-N.; 252:... 2.5. 8:23 . .....- .1 c Figure 3. Effect of day temperature and quantum flux density at various night temperatures on the total chlorophyll content in leaves of marigold 'Petite Yellow'. a) Night temperature 10°C b) Night temperature 15°C c) Night temperature 21°C d) Night temperature 26°C Numbers associated with each isoquant are total chlorophyll (mg dm-Z). Each isoquant differs by 0.5 mg dmfz. A8 A3 285 qmzmmaficmm S 24 a DRY TEHPERRTURE (C) 64 DRY TENPERRTURE (C) o ~80 0 3m 0 gm 0 can 0 . woo. o .80 0 92% 82:5 2.5 522: :91.-. c 2535 P5 omzfl: . is.-. c a E E B A v 24 mm 3... Po ‘0... .0 I}! “on i... .I: Q ‘ Va . ED). 95 g 0” vax x .00. 0 0.098“””””””v)”lflt' ¢.tl.+ttili 1 xxun XXXXSIIIX I, b P ~80 h .80 0 a2“ 0 .2 a . ~80 0 .8" 0 a2“ 2523: 2.5 5232 . E-N.; . 2522.: 2.5 5223 . it -1 . SECTION IV FLOWERING POTENTIAL IN HYBRID GERANIUMS AS A RESULT OF EARLY HEAT AND LIGHT TREATMENT FLOWERING POTENTIAL IN HYBRID GERANIUMS AS A RESULT OF EARLY HEAT AND LIGHT TREATMENT A.M. Armitage and W.H. Carlson Department of Horticultural Science Michigan State University East Lansing, Michigan 48824 Additional Index Words: quantum flux density Abstract: Temperatures of 32-350C combined with 350-800 uE m-zs-1 photosynthetically active quantum flux density reduced flowering time, height, and number of flowers per inflorescence of Pelargonium X hortorum Bailey compared with greenhouse grown plants under northern winter conditions. Three and 5 week plants were more responsive to treatments than 7 week plants. Treatments lasting 9 days reduced flower time compared with 3 or 6 day treatments however all treatments which decreased flower time were likely unmarketable. Most cultivars of hybrid geranium require at least 100 days to flower under northern greenhouse conditions (1,7) and up to 150 days under winter conditions. Time to visible bud is dependent on light while temperature controls time from visible bud to anthesis (2). Supplemental light decreased flower time in many studies (4,6,11) and was most effective in the seedling stage when applied for at least 4 weeks (3,5). The role of temperature in flowering has received most attention in vernalization studies (9,10) in biennials and perennials but little has been done with annuals. Temperature affects the latter stages of flower development however there are no reports of the effect of temperature on flowering when applied during seedling development. 65 66 High temperature in early stages of geranium development caused thermal breakdown of chlorophyll (2) and eventual death but also resulted in early bud initiation. This study investigated the effects of high temperature (26-37OC) and quantum flux density (70-1500 uE m-zs-l) combinations, duration of treatment, and plant age on flowering in hybrid geraniums. Seeds of hybrid geranium 'Sooner Red' were germinated under inter- mittent mist in a soilless media. In a preliminary study (experiment 1), 10 day old plants were placed in growth chambers at 375 i 10 uE muzs-1 and 10, 21, or 32 i 2°C constant temperature. Cool white fluorescent lights provided a 16 hr photOperiod for 4 weeks. Plants were placed in the greenhouse on February 15, 1979 with day-night temperatures of 21 i 5, 18 i 2°C and were allowed to flower. Fertilization with 20- 16-12.2 (N-P-K) liquid fertilizer per irrigation provided 200 ppm N. Control plants were grown continuously in the greenhouse. The time to visible bud (<0.5 cm diameter) and time to first flower anthesis were recorded. Tukey's w test was used for mean separation (HSD) (15). In the second experiment, 3, 5, or 7 week old plants were placed in growth chambers for 10 days starting December 7, 1979 to provide the following constant temperature and light combinations (0C, uE m-Zs_1): treatment 1: 32, 70; treatment 2: 32, 800; treatment 3: 36, 300; treat- ment 4: 36, 300; treatment 5: 36, 1500. High pressure sodium lights for high light levels were suspended above polyethylene chambers equipped with thermostatically controlled forced air heaters to maintain desired temperature. Temperature fluctuated i 3°C and light i 20 uE m-zs-l. After treatment, plants were placed in the greenhouse (21 i 5 day, 18 i 67 2°C night) with control plants. The time to visible bud and first flower anthesis, flower diameter, number of flowers per inflorescence, and vegeta- tive and total height were measured. Treatment means were compared with control by Tukey's w test. To determine proper treatment duration (experiment 3), 5 week old plants were placed at constant 26, 32, or 35 i 2°C and 375 i 15 (high), zs-1 (low) for 3, 6, 9, or 12 days in 70 1 10 (medium), or 8 i 2 uE m" growth chambers similar to those used in experiment 1. Plants treated for 3 days were placed in the greenhouse April 6, 1980 and every 3 days until treatments were completed. Greenhouse day temperatures fluctuated with ambient temperatures and ranged from 20-300C and night temperatures were 18 i 3°C. Time to first flower, vegetative and total height were measured and treatment means compared with control plants by Tukey's w test. Experiment 1. Time to visible bud (VB) and days to flower were reduced at 32 and increased at 10°C (Table 1). Under normal greenhouse temperatures (18-26OC), bud initiation in hybrid geraniums is primarily dependent on light, however these data indicate that temperatures outside this range also influence initiation. High temperature treatment may have caused transition from vegetative to reproductive habit through nutrient mobilization (12), breakdown of flower inhibitors (16), or hormone redistribution (8,13,14). Early temperature treatments caused destruction of chlorophyll in all leaves but did not affect flower development time. Experiment 2. Temperature and light combinations of 32°C-800 uE mI-zs-1 and 35°C-300 uE muzs-1 reduced flowering time compared with 68 control plants regardless of age, however 3 and 5 week plants flowered earlier than 9 week plants (Table 2). High temperature (>350C) and high light (>1000 uE m-zs-l) caused death of young plants while 7 week plants were less susceptible to damage. Plants treated with 32°C-70 uE m-zs”1 did not flower earlier than control plants regardless of age. In general, vegetative and total height, number of flowers per inflorescence, and peduncle length were reduced compared with control for treatments which accelerated flowering time. Flower diameter was reduced significantly only in 7 week plants at 35°C, 300 uE m-Zsm1 compared with control. Although flowering time was reduced at 32-800 and 35°C, 300 uE m-zs-l, the decrease in the number of flowers per inflorescence seriously limits its marketability. Experiment 3. Thirty-seven degrees and 12-15 days killed most plants regardless of light level. High light levels reduced flowering time more than medium or low light at both temperatures (Table 3). In general, there was no difference in flower time due to duration. Reduction in flowering time occurred at 3 and 9 days at high temperature, high light but flowering occurred in less than 90 days at 3 and 6 days of low temperature, high light. These results indicate that high light may be solely responsible for flower acceleration, however the duration of light was too short to affect flower time (3,5). The combination of high light and high temperature appeared to control the beginning of the flowering process. Treatments which caused earlier flowering caused shorter peduncle lengths and generally were unmarket- able. Reduction of flowering time was not evident in experiment 2 which may have been due to seasonal differences. Greenhouse grown control plants started on December 12 (experiment 2) required 141 days 69 to flower while control plants sown on April 4 flowered in 95 days. The response to temperature, light treatments may have been overcome when plants were grown under the more favorable environmental conditions. This study indicates that early heat treatment supplemented with irradiation above 300 uE m-zs-1 may affect flowering time many months after treatment and demonstrates the potential for early flowering in hybrid geranium. At this point the results appear to be too erratic and inconsistent to understand the role of temperature and light in flower acceleration. Although supplemental light has been shown to be necessary for 4 to 6 weeks to reduce flowering time, the plant appears to be more responsive to light when subjected to high temperatures. All treatments which reduced flowering time resulted in unmarketable plants. This does not negate the potential importance of this study, but underlines the necessity of continued research along similar lines. A short pre-transplant treatment which would reduce flowering time without a reduction in quality could revolutionize the production of hybrid geraniums and possibly other bedding crops. 3. 7. 10. 11. 12. 13. 14. 15. 70 Literature Cited Armitage, A.M. and W.H. Carlson. 1979. Hybrid geranium greenhouse pack trials - 1979. Bedding Plant Inc. News. July. . 1980. The effect of temperature and quantum flux density on the morphology, physiology, and flowering of hybrid geraniums. .12 Review. , and M.J. Tsujita. 1979. The effect of supplemental light source, illumination, and quantum flux density on the flowering of seed-propagated geraniums. ‘g. Hort. Sci. 54: 195-198. , and P.M. Harney. 1978. Effects of Cycocel and high intensity lighting on flowering of seed-prOpa- gated geraniums. .g. Hort. Sci. 53: 147-149. Carpenter, W.J. 1974. High intensity lighting in the greenhouse. Michigan State University Res. Report. 255: 1-16. , and W.H. Carlson. 1970. The influence of growth regulators and temperature on flowering of seed-prOpageted geraniums. HortScience 5: 183-184. , and R.G. Rodriquez. 1971. Earlier flowering of geranium cv. Carefree Scarlet by high intensity supplemental light treatment. HortScience 6: 206-207. Chaylakman, M.K. 1977. Hormonal Regulators of Plant Flowering In Plant Growth Regulation. P.E. Pilet (ed.), Springer-Verlag (Berl): 258-272. Clarkson, N.M., and J.S. Russell. 1975. Flowering responses to vernalization and photoperiod in annual medics. Aust. g, Plant Physiol. 3: 207-214. - Evans, L.T. 1969. The Induction of Flowering. Some Case Histories. Cornell University Press, Ithaca, New York. Norton, R.A. 1971. Supplemental lighting of selected annual bedding plants in coastal Washington State. Acta Horticulturae. 22: 131-141. Sachs, P.M. 1977. Nutrient diversion: An hypothesis to explain the chemical control of flowering. HortScience 12: 220-222. Sawhney, S., and N. Sawhney. 1976. Floral induction by gibberelic acid in Zinnia elegans under non-inductive long days. Plants 131: 207-214. Searle, N.E. 1965. Physiology of flowering. Ann. Rev. Plant Physiol. 16: 97-118. Tukey, J.W. 1949. Comparing individual means in the analysis of variance. Biometrics 5: 99-109. 71 16. Zeevaart, J.A.D. 1976. Physiology of flower formation. Ann. Rev. Plant Physiol. 27: 321-348. 72 Table l. The effect of four weeks of constant temperature treatment on 10 day old hybrid geranium 'Sooner Red'. Quantum Flux Temperature Days to Days to Density Visible Bud Flower (uE m'zs'l) ( °c ) 375 10 91 c2 112 c 375 21 68 b 95 b 375 32 33 a 65 a Control 81 be 105 be zMean separation by Tukey's w test (.05) 73 Table 2. The effect of temperature, light combinations and plant age on growth and flowering of hybrid geranium 'Sooner Red'. Treatment Plant Days to Days to Flower No. of ‘Hgight Temp Light Age Visible Flower Diameter Flowers Veg Total (0C) (us m-zs-l) (wk) Bud (cm) (cm) (cm) 32 70 3 115 132 4.5 25 17.5 26.0 5 120 137 4.3 23 17.3 25.2 7 121 139 4.3 20 16.8 24.8 32 800 3 85 115 4.3 17 18.8 24.0 5 78 112 4.6 34 18.0 26.5 7 109 129 4.2 12 17.5 25.5 35 300 3 61 97 4.5 14 15.0 24.8 5. 80 106 4.2 14 15.2 23.4 7 93 119 3.6 12 12.0 19.5 35 1000 3,5 died 7 109 132 4.0 14 19.7 28.7 35 1500 3,5 died 7 102 123 4.0 15 17.1 35.8 Control 124 140 4.5 36 24.5 35.8 HSD (.05) 10 10 0.7 8 3.4 4.8 74 Table 3. The duration effect of temperature, light treatments on flowering and height of 5 week hybrid geranium 'Sooner Red'. Temperature Light Duration Days to Height Peduncle 0 Level Flower Veg Total Length ( C) (dayS) (cm) (cm) (cm) 32 high 3 88.2 16.2 21.4 5.3 93.8 18.2 23.8 5.6 9 76.3 11.0 14.7 3.7 medium 3 92.8 18.2 23.9 5.7 6 93.3 17.0 22.3 5.3 9 96.5 16.3 22.3 5.9 low 91.8 18.2 23.9 5.7 ' 96.2 14.3 20.7 6.3 99.3 15.0 22.2 7.1 26 high 3 89.3 13.6 22.1 8.5 89.3 15.2 21.4 6.2 9 91.5 14.7 22.1 7.4 medium 93.6 14.6 23.7 9.1 90.6 14.8 23.4 8.6 9 91.7 15.8 22.1 6.2 low 94.8 15.3 24.0 8.7 97.0 14.2 18.0 3.8 96.0 15.0 22.3 7.3 Control 95.0 18.9 24.3 6.4 HSD (.05) 6.9 4.3 4.6 5.4