MIMI Hi I I W ’ HUM!!! I 130 521 THS THE EFFECT OF SOME EN‘v’lRORME-NTAL FACTORS {3N fiLCPTCHY Rif-‘ENENG 0F THE 'Z’OMATO 'E‘hgsia far flu flags“ af 3%.; S. MlfiHSGAN STATs‘E UNIVERStTY' {Ema Syiwsirm Weiis 393.63 '75-??st LIBRARY Michigan State University ‘ IHIIIUIIIIIlllilllllllllUHIll!ll}!I‘lllllillllllllllllllll 3 1293 10504 8163 )V153I_} RETURNING MATERIALS: P1ace in book drop to LJBRARJES remove this checkout from .‘IIIESI-IL. your record. FINES wil] be charged if book is returned after the date stamped below. THE EFFECT OF SCRE ENVIIE{UIG“$£NTAL FACTORS ON ELO'ICHY RIPENING OF THE TQiATO By 0tho Sylvester Wells AN ABSTRACT OF A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Horticulture 1963 ABSTRACT THE EFFECT OF SC'X-afi liNVIRONMliNTAL FACTORS 0N BLOTCHY RIPENING OF THE TQuATO By Otho Sylvester Wells Blotchy ripening of the tomato was studied on the basis that this disorder is a result of a critical energy stress in the fruit. Experiments were set up to produce such energy alterations in the plant and thus within the fruit. Nutrition and variety were also included in some phases of the study. Variety resulted in differences in both yield and the incidence of blotchiness; however, there was no correlation between yield and blotchiness from the data of eight varie- ties. Glamour, a low yielding variety, was very susceptible to blotchy ripening. At low, medium, and high levels of fertility, no differences in blotchiness were found. Between blotchy and non-blotchy tissue, there were no differences in mineral composition or in percent dry weight; however, soluble solids were lower in blotchy tissue. High humidity and high soil moisture were non-effective in inducing blotchiness. Treatments of shade, mist, mist plus shade, straw mulch, and a wind barrier were designed to either decrease transpiration or increase respiration to produce a high energy demand in rapidly develOping fruits or a critical 0tho 5. Wells energy depletion in rapidly reapiring plants. However, an unforeseen variable, early blight, intervened soon after treatment began and modified the effect of the treatments. The shade and mist plus shade treatments reduced blotchiness through their influence on reducing early blight. The more severe the early blight, the more defoliation, and, in turn, the more blotchy ripening. It was concluded that the theory of a critical energy stress in the latter stages of fruit development is valid, and that blotchy ripening will occur when a sufficient deficiency of reserve food materials occurs. This defici- ency is thought to be most acute about the time of the second harvest of heavy-fruiting plants. THE EFFECT OF SCI-1E. ENVIRONfziillTAL FACTORS ON BLOTCIIY RIPENING OF THE TOMATO By 0tho Sylvester Wells A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of iASTLK OF SCIENCE Department of Horticulture 1963 ACKNOVJLEDG‘aliI‘JTS The author expresses his thanks to Dr. R. L. Carolus for his advice and assistance during the course of this study; to Dre. 5. T. Dexter, n. R. Dedolph, and D. P. Watson for their counsel and guidance in the preparation of the manuscript; and to Dr. A. L. Kenworthy for his assistance in the chemical analyses appearing in this thesis. Appreciation is also eXpressed to Mr. David A. Gilbart for his valuable assistance in much of the research. ii INTRODUCTION . . LITERATURE REVIEW Nutritional Aspects Environmental Associations Tobacco Mosaic Infection EXPBK IM ENTFLL . . Field Investigations--1961 Field Investigations-~1962 Greenhouse Experiment-~1962 GENbRAL DISCUSSION LITERATURB‘CIThD TRBLE OF COhTshTS Page (DwNN ll 11 18 31 37 39 Table LIST OF T331433 The influence of fertility levels and harvest dates on the average yield and average incidence of blotchy ripening of eight varieties of tomatoes . . . . Influence of variety and harvest date on yield and on percent blotchy ripen— ing of marketable tomatoes . . . . . . Mineral composition of non—blotchy and blotchy wall tissue of blotchy tomato fruj't . O U C O C I O O O O O O C O O The influence of treatment on total yield, proportional yield, and soluble solids of four classes of ripe Fireball tomato fruit . . . . . . . . . . . . . The influence of treatment on yield of fruit diaplaying various degrees of blotChiness O C O O O O O O O O O O O A summary of the seasonal data showing the influence of harvest date and treat- ment on yield, soluble solids, and €01°r O O O O O O O O O O O O O O O 0 iv Page 14 15 16 23 34 INTRODUCTION Blotchy ripening of the tomato is a physiological- pathological disorder characterized by the absence of normal red pigment, lycopene, in localized areas of the fruit wall. Underlying the blotchy tissue there may appear a necrosis of the parenchyma tissue adjacent to the vascular bundles. Low levels of total solids, soluble solids, and organic acids are associated with blotchy tissues (19, 41, 4s). The physiological cause of blotchy ripening is probably related to either adverse climatic, cultural, and/or nutri- tional conditions. Tobacco mosaic virus may have a secondary influence in enhancing this physiological abnormality. Be- cause the biosynthesis of lycopene requires a high level of available energy (30), influences resulting in a low accumu- lation of food reserves in the fruit are suSpected. The exact environmental conditions which will result in blotchy ripening are not known. However, the results of much research indicate that certain environmental conditions or combinations of these conditions may induce the disorder (14, 19, 44). This study was concerned primarily with environ- mental and culturalfactors. Nutritional and varietal factors were, however, introduced in some phases of the study. RthhW 0? LITERATURE Since l92l, when blotchy ripening was first studied (ll, 14), it has continued to be of considerable import. Varied concepts of the nature of the disorder have elicited numerous suggestions concerning its cause and control. Hypotheses as to causation are generally based on the nutri- tional status, environmental conditions, or viral infections (tobacco mosaic virus) of the plant and fruit. Some hypo- theses may embrace the possibility of two or more of the above causation complexes interacting to produce the malady. Nutritional Aspects Bewley and White (2) were the first to use the term blotchy ripening and described it as hard green or waxy areas on the ripening fruit. They indicated that the blotchiness was due to low soil potassium and nitrogen, especially potassium. The uneven coloring was often accompanied by a necrosis of the fruit vascular tissue and a breaxdown of the adjacent tissue with the subsequent formation of canals. Their nutritional investigation showed that the incidence of blotchy ripening could be reduced to less than 1 percent by suitable application of sulfates of ammonia and potash. As they increased the application of nitrogen, potassium, and phosphorous, the percentage of blotchy ripening decreased. They proposed that climatic factors modified nutritional effects. aidson and Stanton's work (27) with "cloud," a local name for blotchy ripening, showed that glucose increased cloud; but if potassium were added, the effects of glucose were counteracted. The omission of nitrogen from standard fertilizer increased cloud, but when high nitrogen was used, there was a marked reduction of the disorder. The high nitro- gen also reduced the cloud—inducing effects of heavy water— ing. The application of calcium chloride essentially pre- vented cloud and reduced the incidence in plants treated with glucose. Winsor,l££_gl. (45, 4b), in tests with different concen- trations of nutrients, found that fruit quality improved up to a nutrient concentration of 225 ppm of nitrogen (potassium nitrate and ammonium sulfate) and 394 ppm of ego \potassium nitrate), but there was a slight reduction in total yield and a reduction in weight per fruit. The concentration of fertilizer salts in the soil solution has been shown to have an indirect effect on the incidence of blotchy ripening. Clay and Hudson (9) found that blossom-end rot was pronounced when the soil salinity was in— creased by the addition of potassium and magnesium sulfates, and that blotchy ripening was highest in non-saline soil. Water was taken up most rapidly when salinity was the lowest. The highest yields of best quality fruit were produced at moderate levels of salinity. In Florida, Geraldson (20) found that the incidence and severity of blotchy ripening was higher when plants were grown in nutrient cultures with low nutrient concentrations and low nitrate/chloride ratios. Belik (l), in a study of the influence of moisture level on plant growth, found that tomatoes produced the highest yields of largest fruit when soil moisture was 60-70 percent as compared with either 40-30 percent or nO-QO percent of field capacity. Environmental Associations With reference to Bewley and White's work (2), Seaton and Gray (33) made a histological study of tissue from blotchy ripening greenhouse fruit and noted that the vascular necrosis of the fruit was not actually a necrosis of the vascular bundles, but a collapse of parenchymatous tissue adjacent to the bundles and anastomosing veins. As the blotchy ripening area was viewed through the epidermis, it appeared that the vascular bundles were affected, due to bands of discolored cellular material lying between the epidermis and the bundles. Gigante (21) agreed with the above observations and, in addi- tion, found that the epidermis of a ripened fruit was often underlain with white spongy tissues, which, in some cases, extended throughout the wall. Both Seaton and Gray (33) and Gigante (21) contradicted Bewley and White's (2) nutritional hypothesis and related blotchy ripening to conditions which prevented the trans- location of elaborated food materials and water from the bundles to the outlying cells. Seaton and Gray (35) prOposed that the primary condition was a withdrawal of water from the fruits during periods of excessive transpiration, occurring U' two to five days before the fruit ripened. Gigante (21) went further and said that the environmental water imbalance occurred when a dry spell immediately followed a wet spell. Under these conditions the fruit experienced a rapid uptake of water followed by a rapid loss of water through transpir- ation. A Danish report (44) also showed evidence that blotchy ripening was probably the result of rapid evapor- ation of water from the plants. Lorenz and anott (29) identified a different type of outer wall disorder, "graywall," which was found only in mature green fruit. Fruits having the disorder were thin- walled on the side exposed to the sun. Another report (40) indicated that "graywall" fruits were watery and thin-walled, and that this condition was due to excessive nitrogen and water. On the other hand, Lorenz and hnott (29) ascribed the trouble to excess heat on the exposed side of the fruit. As the fruit warmed, the water distilled from the warm side to the cooler or shaded side of the fruit. They concluded that if young, immature cells were exposed to high light intensity, and thus higher temperatures, they would not have the turgor capacity to enlarge, hence thin walls. On this basis they recommended the planting of thick foliaged varieties which would provide adequate shade. Corewer- (10) reported that in Florida the first evidence of blotchy ripening, which he called internal brown- ing, appeared in 1927. In the winter season of 1943-1949, the tomatoes in Dade County, Florida, were again severely affected with blotchy ripening. No definite cause could he cited, but the disorder was found to the greatest extent where there was luxuriant vine growth and heavily shaded fruits. Stoner and Hogan (42) made observations similar to Conover's, and on the basis of field and laboratory study, they concluded that blotchy ripening was due to some physio- logical factor, neither nutritional nor viral. Haenseler (22) found blotchy ripening on several varie- ties in New Jersey and postulated a possible three-way inter- action between variety, environment, and virus infection. He observed that the plant tended to recover as the season progressed, for only the second and third harvests of several harvests were seriously affected in the observational year, 1949. aidson and Stanton (27), as well as fills (19), found blotchy ripening to be worse on the lower clusters of heavily fruiting plants. On some plants the uneven coloring per- sisted throughout the season and in such cases, the incidence of blotchy fruit was higher at early and late harvests. £115 (19) reported that blotchy ripening seldom occurred on fruits from the upper clusters. Kidson and Stanton (27) found that steam sterilization of the soil increased blotchiness along with substantial increases in growth and yield. Even though they found that the most susceptible plants were those having luxuriant growth, they also found evidence that heavy de- foliation would increase the disorder. The latter finding contradicts the first but might be eXplained in the findings of Davies (13) who observed that severe defoliation resulted in better grade fruit and reduced the proportion of irregu- larly colored ones, but at the expense of marked yield re- duction. Hall and Dennison (23) set up experiments to observe the effects of shade, moisture, soil compaction, and cool temperatures on the incidence of blotchy ripening. Although shade and mist separately produced blotchy ripening, a combin- ation of the two was more effective than either alone. Soil compaction was noticeably effective, but appeared to be in- significant when combined with shade or mist. Cool night temperature increased the disorder, but its effect was much greater when combined with mist or mist and shade. It may be that the mist intensified the shade and was thus respons- ible for increased blotchiness, or the mist may have been an important water source, since the mist nozzles operated continuously during the treatment. If the latter is the case, it would be in agreement with aidson and Stanton's (27) and Ells' (19) results which showed that heavy watering increased the incidence of blotchiness. COOper (13, 14, 15) and Jones (25) worked with the Specific factors, shade, temperature, and water and their relationship to the incidence of blotchy ripening. These workers concluded that blotchiness was increased with shade, high day temperatures, and a high moisture regime. Other work by Cooper (12) showed that the percentage of uniformly colored fruit increased when greenhouse plants were widely spaced(6 x 6 feet) and when the axillary shoots were retained. He increased yield and the number of fruits per plant, but at the expense of reduced mean fruit weight. At closer spacings, the retention of axillary shoots decreased yield per unit area and the number of fruits per plant, and in that case also, there was a higherpercentage of even colored fruit. The mean fruit weight also increased. These results are not in agreement with the findings of other workers (19, 2!), who found that high yielding plants tended to produce more blotchiness. £115 (19) found that as the ratio between fruit weight and green plant weight in- creased, blotchy ripening increased. Cooper (16) also found that when tomatoes were grown in d-3/4-inch containers, in contrast to being grown in ground beds, and at 60°F. night temperature, rather than at 35°F., the proportion of uni- formly colored fruit increased. Under the same conditions, early yield was increased, but total yield was not. Tobacco Mosaic Infection A recent report (35) on the association of virus with ripening disorders made a distinction between graywall and internal browning. Murakishi (35) reported that internal browning was caused by a strain(s) of tobacco mosaic virus (TMV) and could be seen in either mature green or ripe fruit. 0n the other hand, graywall was restricted to green to mature green fruits. Blotchy ripening was the same as gray- wall except that the former appeared on unevenly colored ripe fruit. Before Murakishi (33) Proposed his classification, workers were relating the internal browning condition of tomato fruit to virus infection. Holmes (24) was probably the first person to propose a definite relationship between strains of IMV and internal browning, even though previously, Selman (39) and Broadbent (8) reported virus infections in tomatoes grown in English glasshouses. Holmes further showed that there was a close association between infected tomato plants and mosaic infected Plantagp sp., which grew near tomato fields. Raychaudhuri (36) found, and Boyle (5) confirmed, that the IMV strain that was associated with internal browning was not the same as the ordinary strain of TMV. Boyle (4) and Boyle and Wharton (7) showed that internal browning could be reproduced in fruits by inoculating large, fruit-bearing plants with tobacco mosaic virus that had been isolated from internally-browned fruits and from foliage of plants that had produced such fruit, but that the inoculation of young plants did not reSult in internal browning. Internal browning was interpreted as a "shock reaction" resulting from virus invasion and accumulation and a hypersensitive response of the host. While Boyle and Wharton (7) could not find any relation- ship between internal browning and the rate of fertilizer application, other work has shown that nutrition significantly influences the incidence of internal browning. Selman (39) found evidence of differing responses of potassium 10 application to blotchy fruit production on virus-infected plants. High potassium reduced blotchy ripening in in- fected plants. However, it appears that the same quantity of potassium applied to control plants resulted in an in- crease of blotchy ripening. Rich (3?) found that high potash could alleviate internal browning in virus-inoculated plants. Cotter (1i) reported that high nitrogen, low potassium, and low boron generally favored blotchy ripening and internal browning; however, Taylor (43) could not re- late the deficiency of boron in plants producing internal browning to the incidence of the disorder. . Murakishi (32, 33, 34) showed that graywall and internal browning could be induced in Imv-free plants by low light intensity or shading. Along with external factors which affect the incidence of blotchy ripening are internal conditions associated with the disorder. The composition of the tomato fruit and of the plant has been studied and definite relationships between blotchy and non-blotchy fruit have been found. Winsor ££_gl. (47, 43) found blotchy ripened fruit to be lower in total solids, sugars, and acidity. fills (19) found that blotchy ripened tissue was lower in dry matter, soluble solids, and reducing sugars than was normal fruit. EXPERIMENTRL Field Investigations-~196l BXperiments were conducted during the summer of l96l to measure the influence of environment, nutrition, and variety on blotchy ripening. fills (19) suggested that a primary cause of blotchy ripening was a carbohydrate stress in the fruit at some critical period during develOpment. Accordingly, a high ratio of fruit to plant weight might impose a carbohydrate stress and the incidence of the disorder might then increase. Thus, yield differences within the same variety but with different treatments night alter plant weight-fruit weight ratios and afford a test of this hypothesis. ' Though fills (19) found no distinct association between nutrient levels and the incidence of this disorder, further consideration of potassium and phOSphorus nutrition was made in this study. Procedure ‘ g The influences of fertility levels, variety, and har- vest date, on yield and the incidence of blotchy ripening in eight varieties (Glamour, Cardinal, Morton Hybrid, Burpee (Hybrid, N3266A, lndian River, Big Boy, and Big Early Hybrid) were investigated. Plants used were transplanted June 1 to the field location with 3 x 5 foot spacing. 11 12 The differential fertilizer treatments were: (1) con- trol, (2) 120 pounds P205 plus 160 pounds x20 per acre, (3) 24 pounds P205 plus 32 pounds K20, and (4) 120 pounds P205 plus 113 pounds £20. All plots were fertilized with 60 pounds per acre of NH4NO3. The soil tested 66 pounds of available phosphorus and :9 pounds of available potassium by the Spurway test (41). Only the fruits of the last two harvests were weighed and graded. Yield and percent blotchy ripening data were sum- marized by analysis of variance. Difference between means were delineated by Duncan's multiple range test. Soluble solids, percent dry weight, and mineral compo- sition values were determined for blotchy and non-blotchy wall tissue from blotchy fruit. Tissue samples were dried at 46°C. for 72 hours and analyzed for nitrogen by the Kjeldahl pro- cedure and for potassium with the Beckman.Model B flame spectrophotometer. A direct reading photoelectric spectro- meter, a "Quantograph," was used for the determination of phosphorus, sodium, calcium, magnesium, manganese, iron, capper, boron, zinc, molybdenum, and aluminum (26). A Zeiss hand refractometer was used for estimating soluble solids. For observational purposes several non-blotchy and blotchy fruits from three successive harvests were uniformly arranged and stored at 65°F. for a period of one week. Many of the blotchy areas were outlined with ink to determine if they would ripen and to determine the pattern of such ripening. 13 Results Neither yield nor the incidence of blotchy ripening was influenced by either fertilizer or the interactions of fertilizer with variety or of fertilizer with harvest date (Table l). The September 19 harvest was generally over twice as large as the September 27 harvest, but the later, lighter harvest had a higher incidence of blotchy ripening than the earlier harvest (Table l). A correlation analysis further showed that there was no correlation between yield and percent blotchy ripening within a given date or between dates. Yield and percent blotchy ripening were influenced by variety and date. For the September 19 harvest, the yield of Indian River and Big Boy were similar (Table 2), and there was no significant difference in percent blotchy ripening. However, for the September 27 harvest, the yields of Indian River and Big Boy represented the highest and lowest values, respectively, but each showed the same prOportion of blotchy fruit. Indian River, N3266A, and Big Boy produced the highest yields, and Big Early Hybrid and Morton Hybrid produced the lowest yields. Glamour, a relatively low-yielding variety, was markedly affected with blotchy ripening, while Indian River and Big Boy were only mildly affected (Table 2). Soluble solids content was higher in non-blotchy wall tissue (3.6%) than in blotchy wall tissue (3.4%) in all varie- ties (odds 19:1). Percent dry weights in the two types of tissue did not materially differ. No differences in mineral composition were found between the two tissue types (Table 3). 14 TABLE 1. The influence of fertility levels and harvest dates on the average yield and average incidence of blotchy ripening of eight varieties of tomatoes. Date Control HP-HK‘ LP-LK HP4MK Average (a) Yield (Tons per Acre) September 19 3.3 9.6 9.5 9.7 9.4 September 27 4.1 3.4 3.5 5.3 4.1 Total 12.9 13.0 13.0 15.0 13.5 (b) Blotchy Ripeningg(% by Weight) September 19 20.5 22.2 21.7 21.9 22.1 September 27 23.9 30.5 29.8 34.5 29.7 Average 22.2 26.4 25.5 28.2 25.9 ‘HP--High phosphorus HK--High potassium L--Low bio-Medium 15 .anoo mo some «a uuwwmo weaned uses one an pascaaou «on one nouns assaou a madam: anaconda >m0uo«n «avowed no endow» nwoxm u n.on use-«4o u m.oe uaoaane n m.em uaosano on o.m~ «namuuuo on n.om «unaeuuo ma o.em eoomnz an n.q~ me museum on o.m~ wanna: magnum nu n.e~ sauna: sauna mam he ~.o~ sauna: «cause a. o.o~ uo>me camean an m.e~ eoomnz u o.aa sauna: gonna: n. v.om sauna: sauna mum a o.mn mom man a n.»« sauna: aauum mum a «.04 son mum a o.ws uu>mm unseen a o.ma aom mum augment and measumwm snuuomm «caucus u n.mn nosed names” a m.o uo>mx nausea e ~.~H uu>me campus 0 m.m~ «comm: nu m.v. «scan: a o.m~ aom mum on o.v« aom men a m.v aauueuao eu ~.a~ saga» anomuu> each» acumen) new: use: can: dance hm unnaouaum on unnuuuaum nowu< uvnlmnohv paowr ummnooau um0u0~o «queued no one oaom> so some «wo>uwn one xuuwww> Ho ounosaunn w.e00awlo« oanwuexuwa mo .N NAQSH 16 TABLE 3. Mineral composition of non-blotchy and blotchy wall tissue of blotchy tomato fruit.‘ Percent of Dry Weight Element Non-Blotchy Blotchy Nitrogen 2.54 2.77 Potassium 4.19 4.52 Phosphorus 0.479 0.554 Calcium 0.23 0.41 Magnesium 0.21 0.21 PPMJ Dry Weight Basis Sodium 160.0 211.0 Manganese 20.0 23.0 Iron 309.0 394.0 Copper 11.0 15.3 Boron 23.2 25.0 Zinc 30.0 32.0 Molybdenum 1.3 1.5 Aluminum 47.0 48.0 ‘Averages of 15, lO-fruit samples. 17 Observations, after a seven-day storage period of field- harvest blotchy fruit, indicated that all of the blotchy areas developed uniform color with the exception of those areas that were underlain with necrotic vascular tissue. These areas re- mained non-uniformly colored in relation to the severity of the necrosis. Discussion Heavy fruiting varieties are thought to be more sus- ceptible to the blotchy disorder (19, 27), but in this study there was no such relationship. The fact that the high pro- ducing variety, Indian River, was mildly affected with blotchiness may be partially accounted for by its being a variety that is known to show appreciable resistance to the disorder. Although Glamour was a relatively low yielding variety, it showed very marked susceptibility to blotchiness. N3266A, a selection for resistance to TMV, was a.relatively high yielding variety which had a high incidence of blotchi- ness. Since there was no correlation between yield and blotchy ripening, it appears that yield in this experiment did not alter the carbohydrate levels enough to influence blotchiness. Thus, the relationship between yield and the incidence of the disorder is eXplained on the basis of plant vigor. Generally, most of the varieties were at their peak of production at the earlier harvest, and the resulting heavy yield apparently utilized any available reserve food materials that may have accumulated during optimum conditions for photosynthesis. The heavier yield at the earlier harvest 13 predisposed the fruits of the later harvest to develop on temporarily weakened plants. Also, at this time the meta- bolic functions of the plant were in a state of decline due to cooler weather and an onslaught of late diseases. If, then, there is a close association between higher yields and increased blotchiness, it must be that these plants were not producing heavily enough to create the necessary stress on carbohydrate availability to the fruits. Since the fertility levels exerted no significant influence on either yield or blotchiness, it may be assumed that for the quantity of fruit produced, the original fertility status of the soil was adequate. The results of the analysis of non-blotchy and blotchy tissue are not in complete agreement with other research. Although there was a significant difference in soluble solids between blotchy and non-blotchy tissue, there was no difference in percent dry weight or in mineral composition. Apparently, a lower value for each of these is not always a true indication of blotchy tissue. Field Investigations-«1962 The purpose of the field experiment of 1962 was to determine if certain environmental factors would induce blotchy ripening, and if so, to what extent. Treatments were chosen which would in some cases reduce transpiration and in others increase respiration. With a hypothesis that restriction of transpiration would result in a rapid 19 enlargement of the fruit and, in turn, create a critical de- mand for energy, treatments were set up to induce these ef- fects. High rates of reapiration are known to rapidly de- plete reserve food materials; therefore, treatments which would increase the respiratory activity were also initiated. Hall and Dennison (23) worked with shade, mist, and a combin- ation of the two to determine the effect on blotchy ripening. This eXperiment involved similar considerations. Procedure Seed of Fireball variety were sown on April 4 and on May 26 the plants were transplanted into the field. The field soil had been fertilized with 300 pounds of 5-20-20 and 40 tons per acre of manure. On July 2 a sidedressing of 100 pounds per acre of ammonium nitrate was applied. Six treat- ments of double-row, eight-plant plots were replicated three times, each plant being Spaced 2-1/2 x 4 feet. The treat- ments were: check, shade, wind barrier, straw mulch, mist, and mist plus shade. To facilitate mechanical adaptations, the mist and mist plus shade treatments were staggered across replications and down the field. All other treatments were randomized within each replicate. The purposesof the shade treatment were primarily to reduce light intensity and increase the temperature, thereby, increasing respiration. The shade material, Lumite saran shade fabric (Chic0pee Manufacturing Corporation, Cornelia, Georgia) covered the whole plot and reduced the light intensity by 72 percent as measured by a Weston Illumination Meter, 20 Model 756, with a quartz filter. The shade fabric was sus- pended two feet above ground level or approximately six inches above the tops of the plants. The wind barriers were to serve as a means of reducing transpiration during windy weather and to increase the temper- ature on a calm day, thus increasing reapiration. White, two-mil polyethylene plastic, 2-1/2 feet high, surrounded the plot. In the straw mulch treatments, wheat straw was placed under and around the plants with some of the straw lightly covering the plants. The purpose was to reduce light intens- ity and to decrease transpiration. The mist was used to reduce tranSpiration. A mist system was set up so that the foliage was kept continuously wet. The misting cycle was regulated by a solenoid valve and a Nist-A-Matic-Model B control system (B. C. Geiger, North Wales, Pennsylvania). This type of system is based on the principle of the weight of water. When adequate water falls on a fine-mesh, stainless steel screen, the screen moves down- ward and depresses a lever throwing a mercury switch, closing the solenoid valve, shutting off the mist. As the water evaporates from the screen, the same as from the plants, the screen tilts up, actuating the mercury switch, Opening the solenoid, actuating a new mist cycle. The mist plus shade treatment was to reduce transpir- ation and light intensity. The same shade material as was used for shade alone was used, and the mist system was the same as for the mist alone. All treatments were set up on July 30 (after harvesting the first ripened fruits) and were not removed until after the last harvest on August 30. All the area in the experiment was kept free of grass and weeds, excepting slight Sprouting of volunteer wheat in the latter part of the harvest season. Irrigation supple- mented normal rainfall so that the plants did not experience drought conditions. Weekly soil moisture readings Showed that the moisture content never fell below 45 percent of field capacity. Neither were there times when the moisture level was above field capacity for extended periods of time. The fruits for which records were kept were harvested from August 4 through August 30. Before August 4, only a few scattered fruits were harvested, and after August 30, there were few fruit remaining. Only the red, mature fruits were harvested for each harvest date. After harvest, the fruits from each treatment in each replicate were separated into four classes: (1) normal (fruits showing no external appearances of blotchy ripening), (2) mild yellow blotch (fruits in which 1 to 25 percent of a fruit was covered by yellow blotchiness), (3) severe yellow blotch (fruits in which over 25 percent of a fruit was covered by yellow blotchiness), and (4) green blotch (fruits showing any amount of green blotchiness; however, this type usually covered more than 25 percent of a fruit). Within each class and for each treatment, the yield was recorded by number and by weight of the fruit. An estimate of soluble solids in a representative sample of fruit in each class was made by 22 selecting from each sample two fruits of similar size, matu- rity, and blotchiness. It was found that soluble solids values for normal fruit and fruit from the mild blotchy class (having 10-15 percent blotchiness) were only very slightly variable (2-3 percent) and that this variability was very in— consistent. Therefore, a blotchy sample having 5-10 percent blotchiness was used for both the normal and the mild classes. For the severe class, samples having from 40-30 percent blotchiness were taken. In this way there were noticeable and consistent differences in the soluble solids estimates. Samples from the green blotch class showed from 25-40 percent green area. The data were summarized by analysis of variance, and differences between means delineated with Duncan's multiple range test. Results Treatment had no effect on total yield; however, within each of the fruit classes, except green blotch, treatment was effective in altering the prOportions of total yield in the various classes (Table 4a and 4b). The distribution of total yield among the four classes showed that the seasonal yield of severe yellow blotch was higher than the combined yield of the other three classes (Figure 1). Normal fruit yield was low, accounting for only 6.4 percent of the total yield (Table 4b). The differences in yield, within each class, due to treatment are shown in Table 5. A significant trend was 23 .AUuOAD cuoum can“ «a we nonmmn .wmcwmmm .Uuue and once om «ammo: «coca no am .e« «a «squeamemwmaa Jen we seaumumcummwm .nu«o«n noouw snow Awa any nusoa .wwcmmn am «menu Heauoo Mo unwwus omauu>a onHe .umauw hon nocsoa :« unmwozu .Anuoaa m mo .o>e. shoe and moo» :« unumvzn .nucmaa Hm scum «mshm.mo umpaflwh es mz «e «i e #1 s «i ovucvuowwmo scuummwemmm o.m «.os m.e s.mm m.e H.4m mm.v e.o omauu>< a.n o.oa H.e ”.oe a.v u.m~ «.e n.a~ unanm-um«: o.n o.oa e.e o.ne ~.e o.b~ ~.v o.o« ununm o.n o.a~ ~.e o.mo e.v n.54 v.e o.m saws m.n H.os ~.e m.ms ~.¢ m.ea m.e m.v nuns: o.n o.ma m.v m.so m.v ~.o~ m.e o.e uomuuem cede n.c o.ma 0.: b.0m m.e m.am n.v n.m guano .Hom .m Halos .aom .m sauce .aom .m «whoa .«om .m wauaoa «sensuous no or no M be e so or nuuon aeouo ouo>om paw: «asuoz nemaom manasom new uses» HaeomaquOua and mz mz mz m2 it is mz s e s as is mz m2 m2 «mucouowwwo uaaummMemmm mm. ~.o new mm. «.om ooo am. m.m men vow. m.m sod em. m.~e omen awauo>< cm. n.n men em. o.s« «we an. ~.o nun mm. s.n nos on. a.on mans ueanm-»maz mm. ~.s cmm mm. m.oa do» on. n.aa mmv em. o.v sod mm. o.~v oped ueuem mm. q.s com mm. m.sm smoa nm. m.» mom mm. 0.4 as mm. m.ee noes «max mm. o.n mes em. ”.on omma cm. «.0 omm mm. o.~ as am. m.~e odes nods: om. «.0 saw am. o.v~ who am. a.» mum cm. s.« «a rm. o.oe oaoa umwuuam ecu: ow. 0.» com um. n.v~ moon on. m.n omm on. Q.“ no em. ~.«e noes guano .:.< .u} .oz .x.< .oz .oz .3.< .oz .oz .3.< .oz .oz u.:.< n.uz u.oz «nauseous :3on 53o 333» 330m rode» e22 15oz 3e; «38. sauna Au. 040540» one .pauma «enamquQOua .oaUm> deuce no nauseous» No ounosAwnm 0A9 .«msuw cacao» «annoumm oaau no nonmeau snow mo nomaoo .¢ mqm<fi 24 .- U! a o a < V) I“ II- < o I. 9! III > C < z 3 8 1‘2 .9 , ‘0 0 383V 83:! mar NI 01 m ’ ...... a 2 ‘3 2: o ..0 I iii: s z , . '-‘-'.'-:-:-:-:-:-;-:-:-:-:v:-:‘z-2.3+:-:-:-:o:-:~:v:-:o:-:-:-:+:4:-.'N /N 5 ! «'- 3 UiBl 6 . S—AUGUSI? The proportion of total fruit yield occur— ring in each class for each harvest. ................................ ..................................................... I HARVES 1' DATE -A - -' -.' -.-.-.'.‘.-.'.'.-.'.'.-.'.-.-.-.-.'.-.‘.'.‘.'.-.-.-.-.-.;.;.;.:.;.;.;. ................ :':':=:-:1:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:;:-:.:-:-:-:‘:~.-.-.-.-.;.;.:.::;:;:;:;:;:;:;:;: l.-.'.'.'.‘.-.'.-.'.-.-.'.'.-.‘.-.'.'.-.-.'.'.'.-.'. ......................................... ................................................. .......................................................................... O O O 8 — 8 v m O'HIA IVIOI. JO 1N3383d 100[ Total yield for each harvest. Fig. 2. Fig. 1. 24 AUGUST HARVEST DATES 25 O N n g»_ 383V 83:! SNOI NI 0131A HARVES T DA TEIS—AUGUS T 100 (”MA 1V101 s0 INJJUJd ’ .e a 3 v o - " — O O .E*- z i s t 2 , . o o- . b zine l] a I I. o o 8. 3 ‘v Total yield for each harvest. Fig. 2. The proportion of total fruit yield occur- ring in each class for each harvest. Fig. 1. TABLE 5. The influence of treatment on yield of fruit displaying various degrees of blotchiness.a Percentage of Total Weightb per Treatment Class Weightc Treatment Weight Normal Treatment Percent Check 1.4 a Check 3.3 a Mist 1.6 a Mist 3.6 a Wind Barrier 1.7 a Wind Barrier 4.0 a Mulch 2.0 a Mulch 4.8 a Mist-Shade 3.7 b Shade 10.9 b Shade 4.6 c Mist-Shade 11.5 b M'ld Yellow Blotch Mulch 6.1 a Mulch 14.5 a Mist 7.5 b Mist 17.3 a Wind Barrier 3.1 b Wind Barrier 20.2 a Check 8.5 bc Check 21.5 ab Mist-Shade 9.2 c Mist-Shade 25.7 b Shade 11.8 d Shade 27.6 b Severe Yellow Blotch Mist-Shade 17.9 a Shade 45.6 a Shade 19.3 a Mist-Shade 49.8 ab Check 24.3 b Check 59.7 bc Hind Barrier 24.9 b Wind Barrier 61.5 bc Mist 27.5 c Mist 62.9 bc Mulch 30.8 d Mulch 72.5 c ‘Weight or percent within a column which are not followed the same letter differ at odds of 99:1. bWeight in tons per acre. cTotal weight per treatment. by 26 clearly indicated as the yield of normally pigmented fruit and the resulting percentage of total yield were highest under the shade and mist plus shade treatments. Shade treatment was effective in producing more fruit in the mild yellow class. Yield from the mist plus shade treatments followed, but was not higher than the yield from the check plots. A lower yield of severe yellow blotch was produced under shade and mist plus shade. Among the other treatments, there were no consistent differences in yield. The relationship between harvest dates and the prOportion of yield in each class and total yield is shown in Figures 1 and 2. Total yield continued to rapidly increase through the last harvest. after which there were only scattered fruits left on the vines. The greatest proportion of normal fruit came with the first harvest, August 4; and from this date there was an overall decline with the succeeding harvests. The green blotch disorder did not appear until the third harvest. August 16. Severe yellow blotch was consistently higher for each harvest than the other classes of blotchiness. The second harvest, August 10, was abnormally high (80.5 per- cent) with severe yellow blotch. On August 10, the remain- ing portion of fruit was almost equally divided between normal and mild yellow. The average weight per fruit was not different between treatments in either the total or the classes, except in the normal class. Between classes, the average weight of normal fruit was lower than the average weight of severe yellow blotch fruit (Table 4a).‘ 27 Within each class, soluble solids were different due to treatment (Table 5), but there was no definite trend indicat- ing that fruit from any particular treatment was consistently lower or higher in soluble solids. Between classes, soluble solids were lower in green blotch fruit. The other three classes had the same value, 4.3, for soluble solids (Table 4b). One purpose of the shade was to increase respiration by raising the temperature; however, the day temperature was 20?. lower under the shade as compared to normal air temperature. Night temperatures under the shade were not recorded, but were probably higher due to the soil heat radiation. Generally, the season was very windy and, therefore, the wind barrier served more to reduce wind movement than to raise the temperature. Early blight, a fungal disease caused by Alternaria solani, appeared around August 10. and by August 16 the plants were from 10 to 40 percent defoliated, and by August 30 the plants were from 40 to 95 percent defoliated. In each case the lowest percentage of defoliation was found with the shaded treatments. The yield of decayed or rotted fruit was very small, ac- counting for only 2 percent of the total. Discussion In this investigation the yield was high, which may, in part at least, be attributed to the fact that only 2 per- cent of the fruits were infected with decay organisms. Along with this high yield was a very high incidence of blotchy 23 ripening. It should be noted that even though many of the fruits classified as mild yellow could be sold on the market, these fruits were nonetheless abnormally pigmented and, therefore, were considered to be affected with blotchy ripen- ing. Ells (19) and Kidson and Stanton (27) found that heavy- fruiting plants tended to produce more blotchy fruit than light-fruiting plants. These workers did not specify the environmental conditions under which they found increased blotchiness with heavier production; but if the carbohydrate status of the plant is a critical factor in influencing this trouble, then it appears that certain environmental factors would cause an increase in blotchiness beyond the point of production effects. Heavy fruiting utilizes a lot of energy and if the plant is unable to synthesize and replenish the necessary metabolites, there will be a rapid weakening of the vegetative portion of the plant as well as a marked de- crease in fruit quality. In agreement with this theory was the manner in which the very high incidence of blotchiness occurred. As previously stated, early blight became an important disease during the time of the second harvest, August 10. From this date until the end of the harvest season, the severity of the disease was exemplified by a constant increase in defoliation. Consequently, as production rapidly increased (Figure 2), there was a consistent decline in normally ripened fruit (Figure l). 29 Bonner (3) stated that a typical leaf is light satur- ated at l0 to 20 percent of full light intensity. Therefore, the upper leaves of the plants were fully light saturated even though they were receiving only 23 percent of full light intensity. However, many of the lower leaves that were cap- able of maximum photosynthesis were probably not receiving even 10 percent full sunlight; hence, the plants were not aCCumulating food reserves at a maximum rate. Therefore, it would be expected that these plants would have weaker vege- tative growth than the plants in full sunlight and, in turn, fruit of lower quality. Conversely, the data well verify that the shaded plants produced significantly higher yields of normally ripened fruit and significantly less of poorly pigmented fruit. These results are most likely eXplained on the basis of the effect of another variable, early blight, and not on a tranSpiration-respiration hypothesis. This fungal disease thrives best in an environment of high temper- ature and high humidity. During the day the air temperature under the shade was 20F. lower than the normal air temperature. Therefore, early blight was less active on the shaded plants. The mist plus shade treatments also reduced the temperature; but, at the same time, the humidity was much higher. At night the tem- perature and humidity effects were reversed. However, the effect was the same as during the day. Under the shade (at night) the heat which radiated from the soil kept the plants dry, while the resulting evaporation of moisture from the 30 leaves kept the plants cool. The plants not covered with shade material were cool but not dry. Therefore, the fun- gal growth was again less active on the shaded plants. Total yield was not reduced as a result of the blight because fruit set and partial fruit development had taken place before early blight infection set in. Only fruit pigmentation was affected by early blight, as is seen by the incidence of blotchiness among treatments. Apparently there was enough available energy for fruit develOpment but not enough for complete pigment develOpment. It may be concluded that this experiment was quite il- lustrative of the effect of a foliage disease on the inci- dence of blotchy ripening. The resultant defoliation sup— ports the work of nidson and Stanton (27), who found that heavy defoliation increased the disorder. On the other hand, Davies (18) found that severe defoliation resulted in better grade fruit and reduced the preportion of ir- regularly colored ones, but at the expense of marked yield reduction. The results of this experiment showed that even with a high yield and with severe defoliation, the incidence of blotchiness was high. Therefore, it is reasonable to propose that there is a definite critical time in the develop- ment of either the plant or the fruit, or both, when a maxi- mum energy deficiency will cause blotchy ripenina. Such a preposal is partially, at least, in agreement with the work of Boyle (4) and Boyle and Wharton (7), who showed that 31 internal browning could be induced by inoculating large, fruit-bearing plants with tobacco mosaic virus, but the inocu- lation of young plants was ineffective in causing internal browning. Since early blight became the predominate factor in this experiment, it is yet unknown if environmental factors exert their influence through transpiration-reSpiration activity. The effects of the treatments on fully foliated plants may result in entirely different results than the treatments on blight-infested plants. Greenhouse Experiment-~1962 During the spring of l962, a greenhouse eXperiment was set up to determine if stringent treatments would markedly induce or increase the incidence of blotchy ripening of fruit from heavy-fruiting plants. The experiment was initiated on the basis of a hypo- thesis that fruits would enlarge more rapidly if the plant had access to an abundance of moisture, both in the soil and in the atmosphere (high humidity). Such treatment would, consequently, create a critical energy stress in the fruit, and thus cause poor pigment develOpment. Geraldson (20) found that the incidence and severity of blotchy ripening was greater when the plants were growing in a culture solution having a low, rather than a high, nitrate/chloride ratio. Therefore, adding ammonium chloride in a water-saturated soil and atmosphere, should hypothetically result in a higher incidence of blotchiness than found in plants with only high 32 water or high water plus high humidity. Conversely, treatment that would limit the available water should result in reduced blotchiness. One method of limiting the water supply would be to increase the osmotic concentration of the soil solution by adding a salt, such as sodium nitrate. Procedure From a greenhouse planting, five Michigan-Ohio Hybrid tomato plants were selected in each of two replicates. These plants were subjected to five different treatments: (1) check (having a low water regime, a regularly weekly watering), (2) high water (two gallons per day beyond normal weekly appli- cations), (3) high water plus high humidity (by covering the plant with a clear plastic cover), (4) high water plus high humidity plus an initial two-ounce application of ammonium chloride, and (5) an initial four-ounce application of sodium nitrate in a gallon of water plus a daily two-ounce application in a pint of water. The eXperimental plants were separated from each other by inserting into the soil sections of six-inch corrugated aluminum lawn edging. When treatment commenced, ten clusters of fruit had set, and the first three clusters had been harvested. The experi- ment was terminated when approximately the tenth cluster was harvested. Therefore, the data are composed of results of approximately seven clusters of fruit per plant. The fruits were harvested in the red-ripe stage. For each fruit, the color was evaluated, the weight was taken, and soluble solids were estimated. Since there was variation in 33 the number of fruit that ripened each day, the results were tabulated on the basis of four, ten-day periods: June 20-30, July 1-10, 11~°o, and 21-30. The data were summarized by analysis of variance and differences between means were compared by "Students" t-Test. Results Although the yield for the various periods and among treatments was quite variable, there was no significant difference in the average weight per fruit (Table 6a and 6b). Soluble solids decreased as the season progressed; however, only the values from the first and last harvest dates were significantly different. Between treatments, soluble solids values from the treatment of high water plus high humidity plus ammonium chloride were significantly higher than either high water or high water plus high humidity (Table 6b). The incidence of poorly colored fruit reached very high percentages, but in this experiment the abnormal pigmentation was not altogether of the classical blotchy ripening type. There appeared around July l a light yellow mosaic pattern of blotchiness, which was found on any segment of the fruit wall, in contrast to true blotchy ripening which is very rarely found on the blossom-end section. The incidence of the mosaic blotchiness increased throughout the season and became very serious around July 21. In Table 6a is shown the relation- ship between season and the incidence of poor pigmentation. As soluble solids decreased, the prOportion of blotchiness increased. Among treatments there was much variation in 34 TABLE 6. A summary of the seasonal data showing the in— fluence of harvest date and treatment on yield, soluble solids, and color. (a) Harvest Dates 1 Poorly Number of Total Average Soluble Colored Date Fruit Wt.(gms) Nt./Fruit Solidsb Fruitc June 20-30 35‘ 6339 153 4.20 a 11.43 July 1-10 62 10397 163 4.19 ab 32.26 July 11-20 17 2941 173 4.05 ab 41.13 July 21-30 43 7532 153 3.87 b 75.00 Total 162 27309 1 .3 Average 41 6327 71 4.03 41.36 Significantd Difference NS ** (b) Treatment Treatment High Water, e High Humidity 40 6023 151 3.94 a 30.00 High water 49 8693 177 3.95 a 59.l3 Check 50 9075 132 4.07 ab _43.00 High Water, High Humidity, NH4Cl 11 2035 157 4.25 b 9.09 NaNO3 12 1461 122 5.03 b 3.33 Total 162 27309 Average 32 5462 164 . 4.23 41.36 Signi icant Differenced NS ** ‘Prom ten plants. Values within a column which are not followed by the same letter differ at odds of 99:l. cPercent of total number per date or treatment. d**Statistically significant at odds of 99:1. eProm two plants for all harvest periods. 35 blotchiness, but there was no apparent relationship with soluble solids. Fruit from treatments involving ammonium chloride and sodium nitrate were markedly lower in the percentage of poorly colored fruit. During the latter days of the first harvest period, the plants treated with ammonium chloride died because of broken stems; and also during the same time, the plants receiving sodium nitrate died because of an excessive salt concentration in the soil solution. Discussion araus and Kraybill (23) found that in the tomato stem there is a carbohydrate-nitrogen gradient. Beginning at the base of the plant and going upward, the nitrogen content in- creases and the carbohydrate content decreases. If such a relationship is true for fruits also, then the soluble solids values for this eXperiment were in agreement; for as the sea- son progressed and as higher clusters were harvested, there was a regular decline in soluble solids. With the check plants under normal growing conditions, it would be expected that fruit soluble solids values would be approximately equal to the average of the values by harvest period. And this was found to be true (Table.6a and 6b). The high soluble solids values shown by the sodium nitrate treated plants is probably not entirely accurate, since these plants were dehydrating before visible symptoms of wilting appeared. The death of the plants treated with ammonium chloride was probably also a contributing factor to 36 the higher soluble solids in this treatment. The low incidence of blotchy fruit on the fertilized plants is related to the fruits' ripening at a time when the seasonal incidence of poorly calored fruit was low. If the plants had survived, the values might have been higher. Consequently, the low percentage of poor fruit cannot be re- lated to high soluble solids. According to the initial hypothesis, an increase in fruit size was a prerequisite of increased incidence of blotchy ripening; however, since neither effect was produced, it may be concluded that this eXperiment was not effective in producing the results anticipated. GENERAL DISCUSSION The primary objective of this study was to determine if there is an association between blotchy ripening and an energy stress in the fruit during its develognent from the almost nature green stage to the red ripe state. The assumption was made that any factor which would create a criti- cal energy demand in the fruit would either induce or increase blotchiness. Therefore, experiments were designed to alter both the anabolic and catabolic rates of metabolism within the plant and thus within the fruit. Treatments were enacted, both singly and interactionally, to study the effects of reduced light intensity, reduced transpiration, increased respiration, nutrition, and variety on the incidence of blotchy ripening. 0n the basis of the results of the experiments con- ducted, there was no conclusive evidence that blotchy ripening could be attributed to any one factor or to any definite com- plex of factors. Even so, the theory of energy stress was amply illustrated as a result of an uneXpected variable, early blight. Since the sole source of the energy of a plant is radiant energy, it is essential to the reproductive functions of a plant that it have efficient photoreceptive organs, leaves. As a consequence of the blight-induced de- foliation, the energy reserves were rapidly depleted as the fruit ripened. Apparently a small proportion of the fruit 37 3:} received sufficient energy, while the majority of the fruit was deprived of the necessary energy for uniform color formation. These results indicate that the theory of energy stress is valid and that regardless of the specific physiological factors involved, any factor that tends to reduce the carbo- hydrate assimilation rate or reduce accumulated reserves be- low a minimum tends to constitute a metabolic deficiency having the visual symptoms of blotchy ripening. 10. ll. 12. LITERATURE CITED Belik, V. F. 1960. The develOpment of tomatoes and the cell sap concentration of the leaves at differ- ent soil moisture levels. Bot. Zurnal 45:1063- 1066. (Hort. Abstr. 31:6449.) Bewley, W. F. and H. L. White. 1926. Some nutri- tional disorders of the tomato. Ann. Appl. Biol. 13:323-328. Bonner, J. 1962. The upper limit of crop yield. Science 137:11-15. Boyle, J. S. 1956. The nature of the internal brown- ing disease of tomato. PhytOpath. 46:7. (An Abstr.) . 1959. The role of tobacco mosaic virus in the internal browning disorder of tomatoes. Phytopath. 49:227. (An Abstr.) and D. C. Wharton. 1956. The experimental reproduction of tomato internal browning by inocu- lation with a virus. PhytOpath. 46:7. (An Abstr.) . 1957. The experimental reproduction of tomato internal browning by inocu- lation with strains of tobacco mosaic virus. Phytopath. 47:199-207. Broadbent, L. 1961. The epidemiology of tomato mosaic: a review of the literature. A. R. Glass- house CrOps Res. Inst. 1960. pp. 96-116. Clay, D. W. T. and J. P. Hudson. 1960. Effects of high levels of potassium and magnesium sulphates on tomatoes. J. Hort. Sci. 34:85-97. Conover, R. A. 1949. Vascular browning in Dade County, Florida, green-wrap tomato. Pl. Dis. Rptr. 33:253- 284. COOper, A. J. 1958. The definition and classification of abnormalities of fruit pigmentation in the tomato variety "Potentate." Annals Appl. Biol. 46: 669-674. . 1960. The effects of plant form and planting density on glasshouse tomato crepping. J. Hort. Sci. 35:103-109. 39 13. 14. 15. 16. 17. 13. 19. 20. 21. 22. 23. 24. 40 COOper, A. J. 1961. Towards precision growing-~control- ling the growth of the glasshouse tomato--III. The Tomato and Cucumber Marketing Board Jour. 10:297-301. . 1961. Blotch research. The Grower Annual. Grower Publications Ltd., London, W. C. pp. 126-127. . 1961. Blotchy ripening of tomato fruit. A. R.“Classhouse Craps Res. Inst., p. 56. . 1962. The effects of sowing date and root restriction on the yield of the glasshouse tomato. J. Hort. Sci. 37:94-105. Cotter, D. J. 1961. The influence of nitrogen, potas- sium, boron, and tobacco mosaic virus on the inci- dence of internal browning and other fruit quality factors of tomatoes. Amer. Soc. Hort. Sci. 73:474- 479. Davies, J. N., D. M. Massey, and G. W. Winsor. 1957, 1959. The effect of defoliating tomato plants on fruit composition. A. R. Glasshouse Crops Res. Inst. pp. 53-66. (Hort. Abstr. 29:2591.) fills, J. E. 1961. The relation of some environmental factors and composition values to blotchy ripening in the tomato. Ph.D. Thesis. Michigan State University. Geraldson, C. M. 1960. Nutritional factors affecting the incidence and severity of blotchy ripening of tomatoes. Florida State Hort. Soc. 73:111-114. Gigante, R. 1958. Blotchy ripening of tomatoes. (Slightly abridged translation from the Italian "La maturazione a chiazze dei frutti di pomodoro." Bol. Staz. Pat. veg. Roma 12:127-136. 1954.) Commonwealth Bureau of Hort. and Plantation Crops. Bast Malling Res. Sta. Query No. 3215. Haenseler, C. M. 1949. Internal browning of tomatoes in New Jersey. Plant Dis. Reptr. 33:336-337. Hall, C. B. and R. A. Dennison. 1955. Environmental factors influencing vascular browning of tomato fruits. Amer. Soc. Hort. Sci. 65:353-356. Holmes, P. 0. 1950. Internal-browning disease of tomato caused by strains of tobacco-mosaic virus from Plantago. PhytOpath. 40:437-494. 26. 27. 28. 29. 30. 31. 32. 33. 34. 3d. 41 Jones, J. P. 1955. 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The influence of lime and potash on mosaic infection in the tomato (var. rotentate) under glass. J. Pomology and Hort. Sci. 20:89-106. Shipping Point Inspection Handbook for Tomatoes. 1957. USDA, Agr. Mkt. Ser., Fruit and Veg. Div. Fresh Prod. Standardization and Insp. Branch. Pp. 31-34. Spurway, C. A. 1938. Soil testing--a practical system of soil fertility diagnosis. Tech. Bull. 132, 2nd rev., Mich. Agr. EXpt. Sta. Stoner, W. N., and W. D. Hogan. 1950. A report of graywall or internal browning of tomato in south Florida. P1. Dis. Reptr. 34:379-380. Taylor, G. A. 1958. Internal browning of tomatoes. Hort. News (N. J. Hort. Soc.) 39:333-335. Tomater uden Grinsajold. 1959. Havebrugets Porskningsfoud. Winsor, G. W., J. N. Davies, and M. I. B. Long. 1961. Liquid feeding of glasshouse tomatoes; the effects of potassium concentration on fruit quality and yield. J. Hort. Sci. 36:254-267. , J. H. L. Messing, and ‘h. I}‘E}‘Long.’71962. “Liquid feeding of glasshouse tomatoes; the effects of nutrient concentration on fruit quality and yield. J. Hort. Sci. 37:44-57. and D. M. Massey. 1957, 1959. Studies of the composition of tomato fruit. A. R. Glass- house Crops Res. Inst. pp. 40-52. (Hort. Abstr. '29:2594.) . 1958. The composition of’tomato'fruit. 1. The expressed sap of normal and Pblotch" tomatoes. J. Sci. Food and Agr. 9:493-495.