‘ III N | [I I I |N II I I I I “1 I 40 I00 (mo THE INFLUENCE OF CERTAIN WATER SOURCES AND PDT TREATMENTS ON THE GROWTH BF REPRESENTATIVE GREENHSIISE PLANTS THESIS FOR THE DEGREE OF M. 8. JOHN E VERETTE WILDE 1936 5 THE:. r‘ In 1 . i1 l-l‘l', fill . 'f" ‘ a n T I (N {I- I I. la" i-t'fi?’ ”if, 36.5 m ‘w—' T" I ' “E INEEJCK E OF CERTAIN unIER SQWECES r‘r '."\f“ T to *erifi T r" 7" «TM 1"“ .‘ a“ [LAD i’K/J. l? ‘ T-‘J‘Xlluai\J-U \/.u .LluJ \JJL H'L4L U13 1". ' fififir‘f"! r r'WT YiT—‘TT TI\1T1 " T" ‘ \Tr\f'1 Eta—able“ Ext; lV—E CPL; uJu-¢;l Jug J?.LJ£K...J.D A Tnesis Submitted to tne Faculty of Michigan State College of Agriculture and Applied Science in Partial Fulfillment of tne Requirements for the Degree of Master of Science 337 John Everette Wilde Degartment of dorticnlture Division of Agriculture 1956 7M/‘w/5/Msz ffl, / / //7 item» 5 Table of Contents Introduction.......................................... l Review of Literatire.................................. 2 Netnods and Katerials................................. 7 Exglanation of Tabular Data........................... 3 Presentation of Data and Diseassion of Results........20 Z‘\, 0‘. Simmarj and Concldsion...............................x ‘3 ACknovv'l-edgmelltOOOOIOOOOOOOOOOOOOOOOOI.OOOOOOOOODOOCOOO‘; Literalthre Cited..o...o............o...........-.o..o.r§7 TEE IiL"TILivClu OF CE‘RTAIJ I’t'AlER 5033035 AND BOT ERLAquJlo Oh THE GROWTA OE T431.) mdzlll.-fIT 42a GlLIJ-IAIIJLQ JOE A’AJIiEXiWS Introduction In recent years the problem of proger water Sdggly for greenhouse crogs has become increasingly important. The use of chlorinating and water softening processes by many Munic- ipal water supply plants has tended to produce adverse soil conditons in greenhouses Which depend on such sources for their water sapply. Since the relationship of clay got containers to slant growth has received considerable attention recently, it seemed desirable to obtain more definite information concerning this relationship under greenhouse conditions. The clay pot has certain progerties which apgarently affect plant growth and these have not as yet been thoroughly investigated. A study of the relation of certain water sources and pot treatments to the growth of representative plants apgeared, therefore, desirable. -2- Review of Literature Recommendations as to the proper sources of water for potted plants have been given from time to time in English and American periodicals and books on gardening. The use of rain water is generally recommended as best for potted plants. No controlled experiments on water sources for greenhouse crops have been reported until recently, however. The porous clay pot adopted by the American Florist's Association, in 1885, as a "standard" pot has been virtu- ally unchanged since that time and is still used, almost to the exclusion of other pot containers. Pre-soaking of new clay pots and washing of used pots has been recommended by commercial growers and horticultural writers and the belief that plant roots are aerated thrOugh the wall of a porous clay pot has been generally accepted until the work of Jones (18, Zl) cast some doubt on this matter. Water source has long been regarded as an important factor in the growth of garden and house plants. As early as 1739, Bradley (4) recommended the use of a "natural" water and suggested that it be held in a cistern or earthen pit for several days before applying it to the plants. Loudon (23) advocated the use of rain water and cited cer- tain experimental results to show that the temperature of the water used should be, as nearly as possible, that of the soil in which the plants are grown. Burbridge (7) -5- stated that the best water for plants is "soft" water, under which heading he put rain and river water. Fish (ll). editor of Cassel's POpular Gardening, advised the use of pond water, where rain water was not available. In this connection gar- deners were warned against the use of water with a high lime content. Regel (24) recommended the use of "soft" river water for watering cuttings, or rain water if a lime-free source was not available. In Le Bon Jardinier (54) certain water sources are compared. Rain water was considered best because it was free of salts and saturated with air. Well- water was considered poorest for watering flowering plants. River water, it was stated, has considerable salts in solu- tion and their nature and amount varies with the Character of the soil through whicn the stream passes. The testing of all water except rain water was advised. Volz and Burk (50) carried on a series of experiments to determine the relation of water sources to the ultimate pH of greenhouse soils and the effect of those sources on the growth of representative plants. This study was carried out in a typical greenhouse environment. They reported that plants do not have a constant pH requirement but rather an optimum for each set of environmental conditions, that the final pH of a greenhouse soil is a direct factor of the water source utilized, and that rain water is apparently the best source of water supply while well water softened by the zeo- lite process appears to inhibit plant growth to some extent. -4- The nature of plant growth in relation to soil reaction is of primary importance in a study of the effect of water source on the growth of greenhouse crOps, since the water affects plants indirectly through its influence on soil re- action. Arrhenius (l, 2, 3) discussed the relation of plant growth to soil reaction and stated that there is a direct correlation between soil reaction and plant growth._ He sug- gested that, in view of wide variations in pH requirements among plants, further study should be made to determine the pH ranges of important plants. Wiggin and Gourley (31) found that no specific soil reaction was required by greenhouse plants used in their study but that a slight apparent depres- sion in growth occurred at neutrality with best results in slightly acid or slightly alkaline soil. Chadwick and Gour-p ley (9) found that certain ornamental plants (Iris germanica, Lupinus polyphyllus, L. hartwegi, Daphne Cneorum, and Del- phinium ajacis) responded best to neutral or alkaline soil reactions. The relation of the clay pot container to plant growth was mentioned by Loudon (25) who stated that the commonly used porous clay pot evaporates considerable moisture from its walls when placed in a dry room. This evaporation, under usual methods of periodic watering, WOJld tend to PTO- duce alternate warming and cooling of the soil mass within the pot, which might prove harmful to the plant grown in it. He suggested glazing the outer walls of pots to control this condition but stated that such measures were unnecessary in the case of potted plants grown in the moist atmosphere of plant houses. Jones (16) reported similar findings and stated that the soil mass within a porous clay pot may be cooled as much as 20 F. by evaporation from its moist outer wall. Jones (16, 17, 18, 21) demonstrated that a clay pot, under condi- tions of low humidity such as are found in dwelling houses, may not be a satisfactory plant container. He recommended (17, 19, 20) the use of glazed or painted pots, or containers made of cement, glass, or metal for growing plants under sucn conditions. The relation of porous clay pots to aeration was mentioned by Sutton (28) wno recommended that used pots be thoroughly washed so that air may more easily enter through their walls. The pre-soaking of both used and new pots was likewise advo- cated. Goff (12) mentioned the value of water movement with- in a clay pot. Where drainage is good and water movement free, 1e considered that watering potted plants at the top forced exhausted air out of the soil mass and facilitated entry of fresn air from the soil surface. The work of Jones (18) snowed that appreciable aeration of plant roots through the walls of a porous clay pot is not probable or even possible. He presented experimental evi- dence showing that, although water passes out of the moist wall of a porous clay pot, no appreciable passage of air in- ward can take place under ordinary conditions. Haber (15) found the porous clay pot superior to peat and composition pots for the growth of certain greenhouse -5- crops. The reason given for inferior growth in peat and composition pots was nitrate deficiency caused by utiliza- tion of soil nitrates in the bacterial decomposition of the cellulose material of which such pots are constructed. The comparison of new and used clay pots and their ef- fect on plant growth was made by several investigators. Thorsrnd (29) found that new clay pots seemed to inhibit the growth 01 plants within them . When compared with plants grown in used pots, there was a noticeable difference in total growth. This he attributed to the presence of toxic substances (probably bases) in the new pots and sxggested washing these out with water or neutralizing them with di- lute acid before putting new pots into use. Knott and Jeffries (22) foand a similar retardation of plant growth in new clay pots. Further investigation showed that this was apparently due to nitrate deficiency, since nitrate feeding of plants grown in new pots corrected the condition. The factor involved was apparently the absorp- tion of nitrates into the walls of new pots. This absorp- tion was much less in used pots, which already had consid- erable nitrate in their pot walls. ' The present study was undertaken with the object of obtaining information concerning certain water sources and pot treatments which might be of value to commercial growers. In order that the results might be more readily applicable to the problems of the average greenhouse grower, this study was based on simple treatments such as might easily be applied -7- by any grower. All trials were conducted in a typical green- house environment and water was applied by generally accepted methods. Eethods and Materials This study was initiated on January 2, 1954 and termi- nated on July 4, 1934. All treatments applied, with the ex- ception of distilled water as a water source, were SJCn as might be used by the average commercial grower. Six hindred potted plants were used in 80 sets involving 4 plant genera, 5 pct treatments, and 4 water s01rces. These were placed on a single, raised, greenhouse bench under con- ditions of temperature and humidity wnich may be considered typical for glasshouse crOps. The external environment of all plants involved in this study was, therefore, the same. Since all plants were selected for uniformity at the time they were entered into the experiment, it appeared that sucn variations in growth as might be noted at the end of the ex- perimental period snould be due to the variable factors of water $01rce, pot treatment, soil type, or genetic and physi- ological variations within the plant species. Water was applied by hose in the manner of the commer- cial grower and watering was done when necessary rather than at definite intervals. The plants in the four water source treatments were separated by low board partitions which could not interfere with plant growth. Unavoidable drips introduced. -8- water from the greenhouse roof into several eXperimental sets but errors due to this source were of minor importance. Chemically softened water was obtained by passing well water through a "Duro" domestic water softener which utilizes the Zeolite process. Since this source was not available before January 20, 1934, all plants to be included in this series were watered with river water until that date. Distilled water was applied through rubber tubing in the same manner in which other waters were applied through lawn hose. Well water was taken from the pipes of the Mich- igan State College Campus water system which pumps its sup- ply from five deep wells (250 to 350 feet in depth). River water was obtained from the greenhouse water supply which is pumped from the Red Cedar river, a tributary of Grand river. All water supplies except the distilled water were taken from pipes within the greenhouse. outlets for each source were placed within a few feet of the bench on which the study was conducted. A comparison of the soluble contents of the va- rious waters is given in Table IA. Five pot treatments were used as shown in Table I. These treatments were duplicated for each water source and plant material used. New and used porous clay pots, in standard sizes, were treated as follows. For the new pot treatments, 560 pots were divided into three groups of l20 each. One group was thoroughly impregnated with hot paraffin at a temperatlre of 85°to 95°C. Since paraffin is practical- ly inert, pots treated in this way are non-porous and equiva- -9- lent to glazed or painted clay pots. One group was soaked in water for 24 hours and used immediately. One group was left untreated. For the used pot series, 240 pots were selected at ran- dom from a group of standard clay pots Which had been in use from one to several times previously. One-half of thi group was thoroughly cleaned with a pot brush and sterilized in a 1-50 solution of pyroligneous acid (l0) and one—half was left untreated. The potting soils used were of two types and may be des- ignated as soils A and B. Soil A consisted of 6 parts com- posted soil, 1 part granulated peat, and 1 part sand. Soil B consisted of 2 parts composted soil, 2 parts granulated peat, and 4 parts sand. Since these parts were measured by volume, as is common greenhouse practice, the proportions by weight would be consiserably different. Soil A and soil B were near- ly neutral in reaction with soil A slightly alkaline. Soil A was high in nitrate nitrogen and soil B rather low in ni- trate nitrogen. All Antirrhinum, Coleus, and hedera helix plants were potted in Soil A and the Begonias were potted in soil 3. All plants were potted in 3—incn pots, excepting the Begonias which were potted in 2%-inch pots because of the small size of the plants at the beginning of the study period. As soon as potted, eacn treatment was marked with a 6-incn wooden stake on which the treatment, the series, and -10- the number of pots involved was printed. The groups of potted plants were arranged according to their treatments and each group watered with the appropriate water source. Care was taken that all potted plants should receive sufficient water throughout the experimental period withOut the soil at any time becoming "water-logged" from over watering. This condi- tion could not be avoided, however, in several pots Which were exposed to overhead drips. The plant materials used were selected as representative: Antirrhinum majus as a cut flower annual; Coleus Blumei as a colored foliage plant; Hedera helix as a semigwoody trailing- vine; and Begonia semperflo*ens var. Wurtemgergia as a flower- ing pot plant. The roots of all plants were shaken free of soil before potting so that no soil would be introduced on the plant roots. The Antirrhinum and Begonia were grown from seed and potted out of flats of transplants. The Coleus and -hedera helix plants were grown from cuttings, the former taken directly from the cutting bencn and the latter taken from 8g- incn pots. All plants in each group were selected for uni- formity of growth. As growth warranted it, the plants were shifted to the next larger size pot. These pots were given treatments iden- tical with the original treatments. All plants were grown for a six months period, with the exception of the Antirrhinum group which matured at the end of four months. Since their retention through the remainder of the period would have made -11- all records of their growth practically valueless, the Antir- mninums were removed at this time. At the time of their re- moval they were in 4 incn pots and, in order that the results on other plant materials Should be comparable, all remaininv plants were carried in 4-pots until the end of the experi- mental period. Some individial plants were pot bound at that time, bit not seriously so. All shifts were made, as nearly as possible, simultane- ously within eacn series. The bench positions were inter- changed eacn month in order that possible differences in light intensity due to bencn position might not cause any growth variations. General notes on foliage color, growth, and habit of plants in each series were taken as observed. Individual plants of Antirrhinum, Coleus, and Begonia varied to sucn an extent in their growth habits that it was evident that comparison of their dry weights was the only feasible method of measuring variations in their total growth. In Hedera helix, wnich developed single shoots, the dry weight comparison could be supplemented by individual shoot growth measurements. These measurements seemed closely related to the total plant growth. At the termination of the stidy period, each set was treated as a unit sample, although either 5 or 10 plants were actually involved. The plants in eacn set were removed from the pots,'roots shaken free of the soil, and placed in a large -12- paper sack. This was marked with tue treatment, series, and number of plants in the set and saved for dry weight determi- nations. All samples were air dried and then brought to a constant weight in an electric oven at 95.0. Twenty-four hours of drying in the electric oven was found to be suffi- cient. Eighty composite soil samples, representing each pot in every set, were taken at the end of the experimental period. These samples were analyzed by the "Simplex" method of soil analysis as described in Kich. Agr. Exp. Sta. Tech. Bul. 132. On the advice of the originator of this system results are given on a comparative basis rather than in actual parts per million. The pd. values were determined electrometically by the use of a calomel cell and quin-nydrone electrode. Explanation of Tabular Data Tables I - V give in a condensed form the treatments used and the results obtained in this study. Table I gives the plant materials, pot treatments, and water sources, and their inter-relation. Table II gives individual shoot length measurements of the Hedera helix plants. These measurements and their averages supplement the dry weight figures given in Table III. Table II snows also that the variations in the growth of individual plants in the same experimental set were considerable. These variations in individual growth -15- rates were observed in all plant materials used. Table III gives the results of dry weight determinations in terms of grams per plant. These figures represent an average of 5 plants in the softened water and distilled water series and 10 plants in the well water and river water series. The dry weights of hedera helix are an exception. These were taken from averages of 5 plants in all the water source groups. Table IV gives the results of analysis of composite soil samples by the "Simplex" method (27). This is given in the form of a general comparison of soil constituents rather than in parts per million. Observed variations in pd values and soil analyses within the same water source group make it evi- dent that tne results may be compared only on the basis of general trends. Table V is in the form of a chart representing the value of eacn water source used. These comparative values are based on plant growth averages computed from the dry weights given. in Table III. Relative desirability is indicated by numerals. Since this ranking varied with eacn plant material used, it was found necessary to make comparisons for each plant series. -14- .A.pnom .am .aov mmafldm cu mafiwaooow msdpsaozmzom .cmmd Hmflhmpwa audam and mondom Hausa 30mm now dopsowamdd ohms muamaudohp pom “ouom GA ans m , OH am>flr o>opm mm m>onw mm o>opw mm o>on ms o>opw mm 0H same cow OH Honda OH nm>fia >H 9 a; m 0H maams o>opm ms m>opw ms o>opm ms m>opm ms o>ons ms 0H mood Scum OH amass 0H Ham; HHH aw I. m n as i o>onm mm o>ops mm m>ops mm o>ops mm m>opw mm a hops: dma Lt m ASEFMH r» condone so: Am [I mpom dmmd .H n dowflafiamum was gonna: n mpom domd .0 season» pod n muOm 303.00 mob mm m flow a. flow a :8 mom E 5.3 308.3 d Hfiom wm dmmsom n opHHoou wfisomm _HHN nonmadmmnm mpom so: .m map as damsmpampad, amflamqm :zqudm: wdmaoo dmpssmmamsfi donouwom muonoawaomamm xaamm manna “madam qflamwasm n hopes wHQQMm shadow adqfisnaHqu mdeoo mpoa so: .4 dame H * pom and m dwmmudainfimap iflqd@l%dddIIIJflflxT MMMWWW dfidfiafiflflm r40 HO oOHH .HOHQB 9:05pmoaw maamfie4mxa adamfiAHmMmNm 33 meanon Hflmda TABQE COEPARISOI OE SOhWfihE SUBSTANCES IN rnrzns UJLJ Water Nitrate “o trce % Cad A 1&1. ff 1:. EQA I, “oftened Water xxxx x_ O O Q Distilled Water 0 O O o 0 Well Water xxxxx xxxxx LL 0 0 River Yatergfi» xxxx xxxx x-xx xx-xxxx c The salt content of the river water was not constant but varied considerably during the exgerimental geriod OD... Xe... XX. 0 o XXXX o XXXXX. Key to symbols .Negative to trace .Low clue d i Shim .xediam to .iiigh .Extremely high -15- fiflflill ddOOT hEHGThS or ALJERA nLLIx * Treat- Aver- .ent Shoot Lengths in Incnes _..4. ages In} ‘ IA 25.5 21.0 25.5 29.0 24.0 13 20.0 21.0 18.0 24.0 17.5 IC 16.0 18.0 17.0 14.0 26.0 ID 18.0 26.5 25.5 18.0 19.0 E 25.5 1.0 16.0 27.5 22.0 Ila 52.0 52.0 55.0 55.5 56.5 113 29.0 57.0 59.0 52.0 51.0 :10 52.0 35.9 56.0 35.0 33.0 IID 54.5 51.0 50.0 51.0 45.0 IIE 57.0 29.0 57.0 56.0 59.5 _‘ h Illa 56.5 41.5 54.5 45.0 25.0 52.5 52.0 54.0 56.0 59.0 55.4 IIIB 59.0 52.0 51.0 54.0 50.0 57.0 41.0 58.0 55.5 54.0 55.2 IIIC 55.0 57.0 21.5 55.0 51.0 25.0 55.0 52.0 57.0 26.0 51.1 IIID 56-0 50.5 57.0 56.0 51.0 52.0 50.0 55.0 50.0 42.0 55.8 Illa 45.5 56.0 52.0 55.0 27.0 29.0 52.0 57-5 ’9.0 55.0- 55.2 IVA 25-0 54.0 54.5 54.5 55.0 51.0 22.0 51.0 7.0 22.0 29.8 1V3 25.0 29.0 59.0 51.0 52.0 52.0 52.0 44.5 55.2 V0 28.0 51-0 50.0 46.5 59.5 57. 0 .5 56.0 F9-5 50.0 55.9 IVD 51.5 50.0 54.0j98.0 26.0 59.0Tg§.M ..0M 9 0 57.0 52.6 IVE 25.0 40.0 55.0 55.0 28.0 50. .0:l55 0 66.0 rl.0 55 8 Legend A New gots waxed I Zeolite softened 3 New gots soaked 24 nOirs well water C New bots untreated II Distilled water D “sed gots washed & sterilized III W'ell water E "sed pots untreated IV River water TABhE III .LJ: Llr -17- V} .1. Ill...) In T." f‘V' r -- 7' w ‘l:. J- 11.1 d4Jh-‘LQ .LJJJlt LJJI~uL Coleis Bldmei Antirrnindm hedera helix Begonia maj :is semoeri‘lorensw treat- pot dry treat- pot dry treat- pot dry treat- pot dry ment- no. wts: lent no. wts. ment no. wtsiqment no. Wts, IA 5 115 I4. 5 5.1_ IA 5 6.1. IA. 5 .0-4 13 .jL 2.2 13 5. 5-7 I3 5 5-6.. I3 5 0.9 I? 5 2-1 I3 .5. 4.9 I0. 5 4.4. 10 5 0-6% 5. 2.7 ID 2.2 ID 5 4.7 10 .5. 1.5 * i 2’2 IE 5-4.1.: I3 5 44...; 4. l... IIA 5 2-7 II“ 5 5.0 Ila 5 6-2 114. 5 1.5 I13 5 -2. 113 5 8-0 113, 5 7-8 IIB 5 2-5 C 5 4-0 ITC 5 7.2. 110 5 ‘.2 I13 5 2-4 I’D 5. 5.0% IID .5. 8-1 IIL 5 1.5 IIL 5 2-4 Him 5 4.2 TIE. .5. 1.8 III ii 305: 113 5 2-4 Illa 10 1.6 Illa 10 5.8 IIIA 5 6.9 Illa 10 0.9. IIIB l0 2.6 IIIB 10 7.9 IIIB 5 7.1 IIIB 10 2.2 IIlC 10 5.1 %IIIC 10 9.2 IIIC 5 7.6 IIIC 10 2.7 IIID 10 5.0 [IIID 10 6.5P' IIID 5 7.3 IIID 10 5.0 III“ 10 2.9 IIIE 10 8.2 .IIIE‘ 5 7.5 #_IIIE 10 2.7f [VA 10 1.5 IVA l0 6.7 IVA 5 4.9.. IVA 10 1.0 V3 10 2.5 IVE 10 9.2 IVE 5 6.0.”.IX3“..10_H2.5_ lVC 10 2.8 IVC 10 7.50 IVC 5 6.0 IVC 10 2.0- [VD 10 2.8 IVD 10 8.5 IVD 5 7.5- IVD 10 2.9 via 10 2.8 NE 10 5.9); IVE 5 6.7 [IVE ___10 :5 0. Dry weights per plant“baséfiffilrififififififlififiififlTfi§WEF'5 of—IE m plants as indicated One *Lfi. plant dea.d. Avera e based on 4 Legend the same as in Table II. Growth retarded by unavoidable overheadtdriis. )CHSO -18- TABuE IV COLBARISON OE AKApYSLd OE DOIQ unnJ.Lo n1 THE TLfiHIHnTION‘Qfi "ids: EXBERIIEIIIAL 921110;). Water pH of Nitrate souroe soil 5011.91 Ca Mg. Na K B N. I 7.5- I softened 7.8- A 0-K x x xxxx xxxxx xxxxx x 7.5- water 8.0 B 1% .. II 6.7- diatii- 7.0 A 0 xx -xx 0 xx xxx xx led .607- meter 7.1 .3 III 701. well 7.6 A O xxxxx xxxxx 0 xx xxx xx "7.1- water 7.6 .3 IV 701‘. river 7.5 .A O-x xxxx xxxx O-x xxxx xxxx xxxx 7.1- water 7.5 .3 f In soil B, treatment IA was an excegtion. This gave a xxxx test for nitrate nitrogen. Ke1_to Symbols 0......Negative to trace O-x....Trace to 10w x......Low xx.....Medium xxx....Medium nigh xxxx...High xxxxx..Extremely nigh II 5.43 44L: V, ‘.‘(“I" 1 n1 v ' - t'l1 fi"! T“."‘X .. -_; ‘.Y" .- r". '..r ."1‘ '7 " 7" x 1'"; 1"" ImbunlIUb .LJJunxl \rlLOu l.l In Immxl 10.1.1 ix) ‘hzm'liul bx) JALL Softened Distilled ‘lants water Water Well Tiger Riverhfloger Begonia fi gemoerflorens 4 5 2 l Antirrninam .gjls 4 5 2 e; l Coleus lumei 4 l 2 ‘7 3 edera elix 4 l 2 3 fl Numerals regresent ranking cf‘water source values as indi- cated by glant growth (Ranking COMQJLEd from averages of dry weignts in Table III). Presentation of Data and Discassion of Results It is apparent from tne results obtained (Tables II, III, V) that tne lse of tap water softened by tae Zeolite process was harmful to tne growtn of plants used in tnis Stde. Tne more succalent plants appeared to saffer tne greatest degree of injury since tne coleis and begonia plants were most af- fected by water from this 801rce. With distilled water taken as tne standard for comparison, tne average growtn of Begonia plants watered witn softened water was 41 per cent pf normal and tnat of Coleas watered witn tne same source, 53 per cent of normal. On tne same basis of comparison, average growtns of Hedera helix and Antirrhinnm in tne softened water series were 68 and 78 per cent of normal, respectively. These per- centages ate based on averages computed from tne dry weignts given in Table III. Analysis of soil samples indicated tnat tne relation of certain soil constituents to each other and to tne soil com- plex as a wnole was reSponsible for variations in plant growtn in tne four water source groups. It seems necesSarj to dis- cuss tnese relationsnips in order tnat tne resalts obtained in tnis study may be better inderstood. Spirway (2?) showed tne effect of certain sollble salts on the solubility of phosphate and (27) gave a practical meth- od of soil analysis. Scofield (25) stated tnat ni r*h alkali L) content of soils is injurioqs due to its effect in lowering -2l- soil permeability as well as to tne toxicity of high ion con- centration in tne plant. Breazeale (5) found that the presence of sodilm in carbonate form innibited tne normal absorption of potassiam and pnospnates by the plant. In a later paper (6) he stated that tne observed toxicity of black alkali soils is not due to direct toxicity of sodium salts but ratner to the indirect effect of sodiim in dispersing the soil to such an extent tnat tne prOper intake of water is prevented. harris (14) observed that soil permeability decreases in proportion to its sodiim Content. Zobell and Stewart (55) found that the addition of organic matter to soils contain- ing large amounts of sodiim carbonate tended to increase plant growtn and partially correct tne toxic eIfect of tne sodidm. From soil analyses (Table IV) it is apparent that sev- eral factors may be concerned in tne sac-normal growtn of plants watered witn zeolite-softened water. The following conditions were indicated by analysis of samples from soils watered witn tnis SOJTCG, througn a six montns period. Low concentration of H ions (pd 7.5 to 8.0). high concentration of Na in tne soil soldtion. High concentration of K in tne soil solition. Low permeability of tne soil,a physical condition attributed to tne dispersion effect of Na and K. Since tne pn values of tne soil samples are witnin tne general range of the plants involved (52) it is not probable that such concentrations of H ions would prove markedly tox- I "(W ~LJ‘I-J- ic to tne plants. Tne absence of cnlorides in tne samples snows that tne sodiim present is apparently in the form of carbonates or bicarbonates, whicn are not hignly toxic (6). Therefore, we may assume that apparent toxicity dde to this water scarce is the resalt of indirect action of Na on tne solubility of K and tae combined effect of high concentra- tions of Na and K on tne physical condition of tne soil. The factors of high ph and high concentrations of Na may, however, have considerable effect in combination with the other factors involved. It may be noted in support of tne foregoing statements that plants in tne softened water series displayed symptoms of poor aeration Sicn as weak root devel- opment (8) foliaQe Changes, and leaf drOp (15) and that soil soldtions from samples in tnis series were extremely dark. From tne pd values of the water sources as given in Table I, it is clearly demonstrated tnat water from streams may be as alkaline as well water and tnat softening of well water by the zeolite process increases its alkalinity. Tne final pH valdes of the soils watered with water from different sources were closely related to tne pH values of the waters applied and varied only sligntly from tnem. Since tne growti of plants in soil has some effect on its altimate pn valde (50) it is possible that some variation is due to tne plant materials used. Distilled water produced better growth in Coleus and -35- Hedera helix plants and appeared to dive Sligdtlj better re- Silts in general than tap water or river water (Table V). Altnongn river water proved best in tne case of Antirrninam and Begonia olants, it was not noticeably superior to tap water, except in tne case of the Jegonia 5roap, wnicn was grown in soil 3. Since soil B was relatively low in organic 'matter, tnis effect may have been produced by tne increase in available nutrients through addition of nitrates and other soluble salts dissolved in tne river water. Tne amount of nitrate nitrogen broagnt in by this water source was variable bit always appreciable (Table IA). The resalts obtained from growing plants in wax-impreg- nated non-porous pots were generally unsatisfactory wnen com- pared witn otner pot treatments (Table III). with one excep- tion, growth was inferior and plants grown in pots of this type displayed symptoms generally associated witn poor aera- ation (8), (l5). Weak root systems and abnormal foliape colors were found in tnis series, particularly among tne Begonias. Witn new pots, untreated, taken as a standard for comparison of tne pot treatments, it was Ioand tnat tne growth of Beyonias in wax-impregnated pots was 4i per cent oi normal while that of Coleis and Antirrnindn was Bl and Va per cent of normal, respectively. Hedera helix was least affected by this pot treatment, its mrowth being 94 per cent of normal. These per- centages are computed from averages based on tne dry weights given in Table III. -24- Jones (18,23 stated tnat air can not pass tarongn tne moist wall of a poroas clay pot. Tne resilts obtained in tnis stady seem to point to better aeration 01 plants in porous tnan in paraffin-impregnated pots. Tne stidies of Jones, men- tioned above, indicate tnat plant roots are not aerated tnrcadn tne walls of porous clay pots. Taking tnis into consideration, tne superior growtn of plants in porous pots may be eXplained by tne following nypotnesis: Tnat tne latera and downward movement of water in a porous pot, produced by tne strong at- traction for water exerted by tne pot mall and tne pall of evaporation from tne cater s1riace oi tnat wall, creates a system of forced aeration tnroagn L46 soil snriace wnicn can not be set up in a non-poroas pot. Tne COMparison of used and new pets in all cases wnere soil A was used as tiie potting .1edi.im snows tnat tnere is no apparent advantage of any one of tde foar porous pot series over anotner. Wnere soil B was used as a potting medium tne two ased pot treatments, L and E, nave a definite advantage over tne new pot treatments, 3 and C. Tnis advanta;e is prob- ably die to tne fact tnat soil 3 nad less available nitrate nitrogen and a pnysiological condition sacn as noted by Knott and Jefiries (22) may nave been bro gut about. Tnat is, tnere may have been partial nitrate starvation in tne plants grown in new pots dde to absorption of nitrates by tne pot wall. Tnis absorption is apparently less pronounced in used pots. In tne Begonia groupysoil from pot treatment A, water source -gs- I, gave a high test for nitrate nitrogen wnereas all otner pot treatments in tnat group gave extremely low nitrate tests. Tnis may have been due to tne fact tnat sucn pots are not porous and, tnerefore, no nitrates coald be absorbed into tneir pot walls. The soaking 01 new pots and tne wasning and steri- lizing of used pcts has no apparent value. Plants droning in tnese pots often made poorer growtn tnan tnose in untreated pots of the sari group. Since tne namber of plants involved in each experimental set was small, tne results obtained in tnis stddy snOdld oe corrorborated by furtner studies on a wider range or green- notse crops. Tue growtn relationsnips observed point to cer- tain conclusions wnicn appear logical, but enoald be confirmed by furtner investigations. SummargL and Concl Hill on Data collected in tnis study points to the following conclusions. 1. The use of well water softened by tne zeolite process is deleterious to plant growtn and tne observed toxicity of tnis water source is probably tne resultant of several factors caised, directly or indirectly, by tne substitution of sodium for calcium and magnesium. 2. Plants vary in their response to such toxicity and tne ( more succulent plants are apparently most susceptable to -36- injdry from zeolite softened tater. 3. Tne SibstltutLon of river for well water ma; not reduce alkalinity or prove in any way advantageots to dreennoase crOps, except when dealing witn soil low in nitrate nitrogen. 4. Tne use of non-porous clay pots (as exemplified by paraffin impregnated clay pots) may be disadvantageous to tne growtn of plants in a typical dreenn0use environment. 5. Plants ;ronn in used pots are not superior to taose grown in new pots unless tne nitrate nitrogen content of tne potting soil used is low. 6. Plant growtn in new pots is not appreciably affected by pre-soaking of LAB pots and Mhfiulhd and sterilizing of used pots nas no apparent valde. Acknovledpment Tne writer takes great pleasure in GXQTESSLDJ nis sincere appreciation of the assistance rendered by otners: firof. V. R. Gardner for lSEful criticisms and suggestions; Prof. F. C. Bradford and Prof. C. E. Wildon for nelpfdl saggestions and translations, and Dr. C. H. Spnrwaj for certain interpreta- tions of soil analyses. Literature Cited Arrhenius, 0. Absorption of nutrients and plant growtn in relation to H ion concentration. Joar. Gen. Buysio. 5: 91. 1922. Soil acidity and plant growtn. figl. Landtbruks Akad. Handl. Tid. 64: 50-67. 1925. From Cnem. Abst. 19: 2254. 1925. Soil reaction and tne growtn of nigner plants. k.) Zeitscnr Blanzenernanr-u-Landung. 4A: 50-53. 1355. From Cnem. Abst. 19: 2720. 1925. Bradley, R. Improvements of Planting and Gardening p. 554. London. 1739. Breazeale J. F. Effect of sodium salts in water cultures on the absorption of plant foods OJ wneat seedlings. Jour. Arg. Res. 7: 407-416. 1916. A a study of the toxicity of salines tnat occur in black alkali soils. Ariz. Agr. Exp. Sta. Bul. 14: 337-357. 1929. Burbidge, F. W. Domestic Floricaltare. p. 49-55 London. 1875. Cannon, W. A. Pnysiological features of roots witn especial reference to tne relation of roots to aeration of tne soil. Carnegie Inst. Wasn. Pub. 568. 1925. Chadwick, L. C. and J. u. Gourlej. Tne response of some 10. 11. 13. 14. 16. 17. 18. 19. ~28- ornamental plants to soil reaction. Amer. Soc. Hort. Sci. Pro. 29: 550-553. 1932. Doran, W. L. Annual report for tne fiscal year of 1931. 'Hass. Agr. Exp. Sta. Bul. eso. 1932. Fisn, D. T. Cassil's BOpdlar Gardening. III: 168-169. 1884-1886. Goff, E. P. The Principles of Plant Culture. pp. 65-150 .ew York. 1916. Haber, E. S. Tne effect of various containers on tne growtn of vegetable plants. Iowa Agr. Exp. Sta. Bul. 279: 149-164. 1931. Harris, A. B. Effect of replaceable sodium on soil per- meability. Soil Sci. 32 (6) 435-436. 1931. Howard, A. and G. L. C. fioward. Soil ventilation. Agr. Res. Ins. of Pisa (India) Bul. 52. 1315. Jones, L. A. Effect of Strdcture and moisture of plant containers on tne temperature of their soil con- tents. Jour. Afir. Res. 42: 375-578. 1951. Flower pot composition and its effect on plant growtn. Kass. Agr. Exp. Sta. 3d1. 277: 148-161. 1951. Aeration of soil in plant containers. Florist's Exchange and Hort. Trade World. 79 (ll) 79. 1932. Cement flower pots. Florist's Exchange and Hort. Trade World. 80 (2) 9. 1932. -29- 20. Jones, L. H. Cogoer and brass containers. Florist's Excnange and .ior‘t. Trade World. 81 (514) 14-15. 1933. 21. Absorotion and evaooration of moistdre from giant containers. Jonr. Agr. fies. 48 (8) 511- 516. 1934. 22. Knott, J. E. and C. D. Jeffries. Containers for giant growing. Penn. Agr. Exg. Sta. Sal. 244.1929. 23. London, J. C. The Horticultdralist. Rev. ed. gar. 25m, 421, 823. 1860. 24. Hegel, E. Vermenrang ddrcn stecklinge. Scnweizeriscne Zeitscnr f. Gartenbad 1V6 2-8. 1846. 25. Scofield, C. S. Alkali problem in irriQation. Ann. Regt. Smitnsonian Inst. 213-223. 1921. 26. Sgarway, C. d. Some factors infl1encing solubility of pnospnords in soil - acid gnosonate mixtur :3. Soil Sci. 19: 399-405. 1925. 27. A gractical sgstem of soil diagnosis. hicn. +1 Agr. nxg. Sta. Tecn. 341. 132. 1933. (0 2o. Sitton and Sons. Tne Cultdre 01 Vegetables and Flowers. Std Ed. 9. 323. London. 1913. {\3 (O Tnorsrld, Arne. Efiect on glants 01 commercial brands of flower gots. Hordes Landbrdk, MeldinJer. 7; 644-662. 1927. (From 3311511ij Sanmarj 661-662). 30. Volz, E. C. and E. F. Bark. Tne effect of hard and soft waters on tne growth of some giants inder green- 31. 33. 34. -30- house conditions. Amer. Soc. Hort. Sci. Pro. 25: 228-233. 1929. Wifigin, W. W. and J. n. Gourley. otddies in tne reac- tion of greennoase soils to tne drowtn 01 giants. Onio Agr. TKg. Sta. Bdl. B4. 1931. Wherry, L. T. Soil reaction in relation to norticnltnre. Am. Hort. Soc. Jul. 4. 1920. Also sapolenent to Am. Hort. Soc. 3J1. 4. Reorint from Hat. Jort. Mag. Oct. 1931. Zobell, I. B. and G. Stewart. Brogress renort of Carbon Co. Expt. Farm. ?tan Agr. Exg. Sta. 331. 225. 1931. Anony. Le Bon Jardinier p. 169-173. 142th Ed. 1911. 3 1‘3“: 4%?! y? {1be 1.5.3» 11.1.4 MICHIGAN STATE UNIVERSITY LIBRARIES II II II IIIIIIIIII II 1293 03178 6050