Advances in Botany T H O M A S G . PHILLIPS
The University of New Hampshire, Durham, Ν. Η.
Growth and Stimulants
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TUDIES of the effects of vitamins, hormones, and other substances on the growth of plants have con tinued with increasing momentum. As is t o be expected in a new field of science which is developing rapidly, the results are rather confusing and some of them are apparently contradictory. Some striking effects of vitamin B1 in increasing plant growth have been re ported in popular journals, and commer cial preparations have been promoted with rather ambitious claims. Shive (31), New Jersey, and Hitchcock and Zimmerman (18), Boyce Thompson In stitute, both have warned that much more study is needed before t h e real value of vitamin B1 in practical plant growing can be assessed. T h e latter authors ob served a stimulating effect of B1 and B6 o n root formation in cuttings of many plants. Arnon (2), University of California, also suggested that B1 may be helpful i n the rooting of cuttings. His cultures of tomato, lettuce, cosmos, mustard, and cocklebur, grown from seed under favor able conditions, did not respond with in creased growth to additions of this vita min. In sand cultures Bonner and Bonner (5), California Institute of Technology, found that the growth of cosmos and mustard plants was promoted by the root growth factors, nicotinic acid, vitamins B1 and B6, by the leaf growth factor adenine, and also by uric acid and estrone. Tomato and wheat plants did not respond to any of these substances, although both nico tinic acid and vitamin B6 are essential t o the good growth of isolated tomato roots. It appears that if grown under favor able conditions many plants form these essentials rapidly enough to support nor mal growth. It is possible also that sup plies of at least some of them may occur in fertile soils. In experiments by Dennison (10), University of Iowa, the growth of eggplant in a quartz gravel medium was im proved by riboflavin and that of tobacco by ascorbic acid. Bonner (4) tried the effect of some 23 compounds closely related to nicotinic acid on the growth of isolated pea roots and showed that only those yielding that acid on simple hydrolysis could replace it as a growth factor. Bonner (6*) has also reported on the ef fect of several growth-promoting subetances on the isolated roots of seven species of plants. Growth of roots· of
U . S . D . A . PHOTOGRAPH BY PETER K I L L I A N
Experimental soybean plants receive different kinds of nutrient solutions alfalfa, clover, and cotton was improved by vitamin B1 and by nicotinic acid. N o additional effect was produced by vitamin Β6. Datura and sunflower roots were stimulated by all three of these substances. Vitamins B1 and B6 increased the growth of carrot roots, but nicotinic acid had no further effect. Tomato roots were affected much as were those of car rot, but nicotinic acid produced some ad ditional effect. Roots of flax and clover grew slowly with no added vitamin B1. They appeared to synthesize small amounts of this substance in vitro. Nobécourt (25) found that growing fragments of carrot root, repeatedly subcultured in a synthetic medium, continued to form vitamin B1; but Gautheret (13) reported that vitamin B1 had an appreciable effect on the growth of such fragments in an agar medium. According to Hartt (17), Hawaiian Sugar Planters' Association Experiment Station, the formation of sucrose from glucose by aerated excised roots of sugar cane i s increased by each of the following substances in decreasing order: riboflavin, ascorbic acid, NaH 2 PO4, and vitamin B1. Burrell and Whitehouse (8) in California more than doubled the set of fruit in muskmelons by- applying indole acetic acid t o one lobe of the stigma. The fruit produced the normal number of good
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seeds. Zika (89) increased the yield of potato tubers and the size of the starch grains by treating the seed pieces with indole acetic acid. Traub et al. (32), U. S. Fruit Field Station in Florida, induced flowering in pineapple by treating for 24 hours, under a movable cover, with one part of ethylene to 1000 parts of air. In southern Georgia peach trees sometimes fail to begin growth promptly in the spring because they have not been subjected to enough cold weather to break their dormancy. About 1000 to 1100 hours' exposure to temperatures below 45° F. is needed. According to Weinberger (88), U. S. Department of Agriculture, spraying with dinitro-o-cyclohexylphenol or some other dinitrophenols can take the of some 200 to 300 hours of low temperature in breaking the rest period of peach trees. Van Overbeek (33), California Institute of Technology, found that traumatic acid (l-decene-l,10-dicarboxylic acid) and thiamine are essential growth factors for some algae. Guthrie (15), Boyce Thompson Institute, was able to inhibit the sprouting of potato buds by treatment with the vapor of the methyl or ethyl esters of naphthalene acetic acid. The, inhibition was removed by treatment with ethylene chlorohydrin. H e also reported (16)
January 10, 1941
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iieaSauL-. U . S. D. A. PHOTOGRAPH BY MYDANS
Study of apple trees grown in pots of sand to which different chemicals are added. that treatment of dormant potato tubers with ethylene chlorohydrin induced an appreciable glutathione content in the tissue and t h a t treatment of t h e tubers with similar amounts of glutathione had an effect on t h e rest period similar to that with ethylene chlorohydrin. Many varieties of apples would look better and taste better t h a n they usually do if picking could be delayed a few days. Perfectly sound fruit persists in dropping from the tree before it has reached that stage of maturity which would bring it to the market in the best condition. Since drops are bruised and n o t marketable, this makes it necessary to pick ail the apples too soon. Gardner, Marth, and Batjer (12), U. S. Horticultural Experi ment Station, Beltsville, Md., have found that a small amount of naphthalene acetic acid or its amide applied t o the stem of the fruit delays this drop materially. The effect of the chemical is noticeable within two days after its application and the length of the effective period differs with the variety of apple and perhaps with environmental conditions. For Mcintosh apples the treatment remains effective for only eight or nine days. For other varieties the period may extend over two or three weeks or even a month. Proper timing is essential t o produce the desired result. If the material is used too often or too near harvest time, t h e stems may stick so tight to t h e tree t h a t picking is difficult. T h e material is applied to the tree in a spray containing about 0.001 per cent of t h e active substance. Com mercial preparations are available for this purpose.
ment to delay the defoliation of holly wreaths and sprays. This loss of leaves may be very serious, especially if the holly is kept under conditions of high humidity.
Plants as Laboratories Plants may be induced t o build up com pounds that are quite foreign to them.
25 On treating potato tubers, gladiolus corms, carrot roots, or the tops of wheat plants with ethylene chlorohydrin, Miller (24), Boyce Thompson Institute, has shown t h a t they synthesize β-2-chloroethyl-d-glucoside. When treated with o-chlorophenol, gladiolus corms and tomato plants produce B-o-chlorophenol gentiobioside. Tomatoes form β-trichloroethyl gentiobioside from either chloral hydrate or trichloroethyl alcohol. I t is not known whether the treatment stimulates the for mation of gentiobiose or whether this disaccharide is present in plants more gener ally than has been recognized. According to Markwood (22), U . S. Department of Agriculture, some strains of tobacco recently developed for low nicotine contain considerable amounts of nornicotine. This may amount t o as much as 95 per cent of the total alkaloid content. This compound is considerably less toxic than nicotine to animals, b u t it appears to be at least as toxic as nicotine to insects. Such organic acids as malic, tartaric, and citric have long been considered as rather curious by-products of plant metabo lism, or of importance only in a limited number of plants of certain families. Chibnall (9), Imperial College, London, and Vickery et al. (35), Connecticut Agri cultural Experiment Station, New Haven, have ascribed to these and related acids a central role in plant metabolism a s the link connecting fats, carbohydrates, and nitrogen compounds in their complex interchanges in the plant. The mechanisms suggested are based partly o n experi ments with plants, partly o n related reac tions in animals, and partly on theoretical considerations. More facts have become
U . β. D . A. PHOTOGRAPH BY PURDY
Milbrath and H a r t m a n (23), Oregon State College, have used t h e same treat-
Premature dropping of apples can be prevented b y spraying the ripening fruit with a hormone solution. Soap solution is added to the mixture as spreader for the spray.
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Vol. 19, No. 1
long exposure of available through plants t o concenthe enzyme studies trations of sulfur of Jacobsohn and dioxide too low to Soares {20). They produce visible infound B-aconitase, jury has no detriwhich reversibly mental effect on hydrates aconitic growth or yield. acid to citric acid, In fact, if the soil in many plants but is somewhat denot in all. It is ficient in sulfur the usually accompresence of small panied by a-aconiamounts of sulfur tase, which reverdioxide in the air sibly hydrates may prove beneaconitic acid to isoficial. citric acid, and by fumarase. The report by Virtanen et Isotopes al. (37) of the ocBarley plants currence of ketowere reported by glutaric, oxalacetic, O v e r s t r e e t and and pyruvic acids Broyer (26), Uniin p l a n t s a d d s versity of Califurther items that fornia, as absorbing fit in with the proradioactive and posed schemes. nonradioactive poGralen and SvedU . S. D. A . PHOTOGRAPH BY MYDANS tassium from a berg (14) have obHybrid and inbred cucumbers produced in the study on vegetables that will resist disease nutrient medium in served the behavior nearly constant proin the ultracentriportion if the level of potassium supply sitates a change in the amount of at least fuge of the soluble substances of high were low. At higher levels there was no one other ion, thus introducing at least molecular weight in tubers, bulbs, or roots net absorption of potassium, but a n extwo variables instead of one. Albrecht of plants of the families including lilies, change of nonradioactive element in the and Schroeder (1), University of Misamaryllis, and iris. In Lilium speciosum tissue for the radioactive in the medium souri, avoided this difficulty by mixing and Narcissus leedsi, carbohydrates were occurred. with the sand a colloidal clay (Beidellite) found of average molecular weight of prepared from a subsoil containing large The movement of radioactive phos20,000 and 50,000. However, they apamounts of this constituent. Ions may phorus supplied by Biddulph (3), Washpear to be polydisperse in contrast to the be adsorbed on this clay instead of being ington State College, to bean seedlings globular proteins. present in solution paired with ions of opwas rapid, following the transpiration The stringent restrictions placed on posite charge. stream. After four hours radio phoshemp have made it practically impossible phorus had accumulated in the terminal Schlenker (29), Rhode Island, sugto continue the use of the crystalline parts of the plants, gested the use of permutite for the adglobulin, edestin, which has long served In corn plants, studied by Brewer and sorption of cations and aniline black for as a standard laboratory preparation and Bramley (7), U. S. Department of Agrianions. Samples were prepared in which as a basis for studies in nutrition. Vickery culture, the movement of radio phosphorus each of the ions needed was adsorbed in et al. (36) have suggested that the globulin was slower, but quite uniform distribution known amount. By mixing suitable of the pumpkin seed would meet the was obtained eventually. Entrance t o weights of these preparations, nutrient requirements of low cost and ease of the plant was delayed greatly by darkmedia were made in which each ion was preparation. Further studies of its cheminess, low temperature, or an atmosphere varied independently. Preliminary tests cal and nutritive properties are in progress. of carbon dioxide. If the plants were have shown excellent growth of plants in Gaffron (11), University of Chicago, removed to solutions containing no radiosuch media. has found that if green algae of certain active elements, they lost some radio families are incubated in the dark for The effect of sulfur dioxide on plants phosphorus from the roots and lower some hours in an atmosphere of nitrogen has been a matter of practical as well as stems, but loss from the leaves was very or hydrogen and then exposed to light of scientific interest for many years. The slow. Under similar conditions radiorather low intensity, they are able to use injury caused by high concentrations of active sodium migrated from the plant molecular hydrogen to reduce carbon this gas in the air are very evident, but quite rapidly. dioxide. This is a light reaction, but if there has not been agreement as to the the light becomes more intense it stops, effect of prolonged exposure to concenRuben et al. (28), University of Caliand soon normal photosynthesis begins. trations too low t o produce visible injury. fornia, used radioactive carbon in a study Two elaborate sets of experiments inof photosynthesis in the single-celled Some plants growing in soils containing cluding this phase of the problem have green alga, Chlorella. C*O2 was reversibly selenium fix appreciable quantities of been reported recently. reduced in the dark; a very large part of this element in organic combination. it was fixed in organic acids. I n t h e Horn and Jones (19), U. S. Department of The studies at the Boyce Thompson fight a much smaller proportion of the C * Agriculture, have isolated from such mateInstitute, published in several papers, fixed appeared in this type of combinarial a substance containing both selenium have been summarized by Setterstrom tion. and sulfur, and having the properties of an (SO), Those carried out in connection In experiments b y Ruben et al. (27) amino acid. with the international question of fume small amounts of gaseous radioactive damage from the smelters at Trail, nitrogen (N 1 3 ) were fixed by the tops of British Columbia, under the direction of When the usual solutions of salts are barley plants. Whether this represented the Canadian National Research Council, used for growing plants experimentally net fixation or interchange is not clear. have been reported by Katz and his assoin either solution or sand culture, a Vickery et al. (34) supplied rapidly ciates (21). Both are agreed that very change in the amount of one ion neces^
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January 10, 1941 growing tobacco plants with a nutrient solution containing ammonium chloride, part of the nitrogen of which was N 1 5 . The most intense absorption of the iso tope was in the roots, but the greatest amount was present in the leaves. I t was found in the amides, amino acids, and proteins separated from these tissues. T h e amount fixed could be accounted for partly b y growth, but to some extent its presence must have resulted from inter change. Literature Cited
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(30) Setterstrom, C , Ind. Eng. Chem., 32, 473 (1940). (31) Shive, J. W., N. J. Agr. Expt. Sta., Circ. 399 (1940). (32) Traub, H. P., Cooper, W. C , and Reece, P. C., Proc. Am. Soc. Hort. Sci., 37, 521 (1940). (33) Van Overbeek, J., Proc. Natl. Acad. Sci., 26, 441 (1940). (34) Vickery, H. B., Pucher, G. W., Schoenheimer, R., and Rittenberg, D., J. Biol. Chem., 135, 531 (1940). (35) Vickery, H. B., Pucher, G. W., Wakeman, A. J., and Leavenworth, C. S., Conn. Agr. Expt. Sta., Bull. 424 (1939). (36) Vickery, H. B., Smith, E. L., and Nolan, L. S., Science, 92, 317 (1940). (37) Virtanen, A. I., Arhimo, Α. Α., and Suomalainen, H., Nature, 144, 597 (1939). (38) Weinberger, J. H., Proc. Am. Soc. Hort. Sci., 37, 353 (1940). (39) Zika, M., Planta, 30, 151 (1939).
27 A l c o h o l Statistics TΗΒ Bureau of Internal Revenue, Alcohol Tax Unit, U. S. Treasury D e partment, has released statistics on alcohol for the fiscal year ended June 30, 1940. More ethyl alcohol was produced dur ing the past fiscal year than in any previ ous year. The production of ethyl al cohol amounted t o 243,727,766 proof gal lons, compared with 201,017,546 in the fiscal year 1939, and 201,033,858 in 1938. Withdrawals in the fiscal year 1940 ex ceeded production by 8,092,972 proof gallons. The number of industrial alcohol plants operated was 37 compared with 36 for both the fiscal years 1938 and 1939. One new alcohol plant in Louisiana and an experimental plant in California began operations during the past fiscal year. The amount of molasses used in the pro duction of ethyl alcohol increased, and the consumption of corn and other grains decreased. The relative production of alcohol from various materials in 1940 follows: molasses, 68.6 per cent; ethyl sulfate, 25.1; grain, 5.7; and miscellane ous materials, 0.6 per cent.
(1) Albrecht, W. Α., and Schroeder, R. A. Proc. Am. Soc. Hart. Sci., 37, 689 (1940). (2) Arnon, D . I., Science, 92, 264 (1940). (3) Biddulph, O., Plant Physiol., 15, 131 (1940). (4) Bonner, D., Plant Physiol., 15, 553 (1940). (5) Bonner, D . M., and Bonner, J., Am. Transportation of Explosives J. Botany, 27, 38 (1940). (6) Bonner, J., Ibid., 27, 692 (1940). REGULATIONS for Transportation of Ex (7) Brewer, A. K., and Bramley, Α., plosives and other dangerous articles b y Science, 91, 270 (1940). land and water in rail freight, express, and (8) Burrell, P. C , and Whitehouse, T. W., Proc. Am. Soc. Hori. Sci., 37, 829 baggage services, and by motor vehicle (1940). (highway) and water, including specifica (9) Chibnall, A. C , "Protein Metabolism tions for shipping containers, have been in the Plant", New Haven, Conn., issued by the Interstate Commerce Com Yale Univ. Press, 1939. (10) Dennison, R., Science, 92, 17 (1940). mission, Washington, D . C , as a 220(11) Gaffron, H., Am. J. Botany, 27, 273 page book. This contains revised regula Toluene from Petroleum (1940). tions, effective January 7, 1941, and is (12) Gardner, F. E., Marth, P. C , and accompanied by mimeographed supple T H E first barrel of toluene from Ameri Batjer, L. P., Proc. Am. Soc. Hort. mentary order dated November 26, 1940. Sci., 37, 415 (1940). ca's first petroleum toluene refinery, (13) Gautheret, R., Compt. rend., 210, 186 Copies m a y be obtained from the Super in Houston, Texas, was taken off more (1940). intendent of Documents, Washington, than a month ahead of schedule, the Shell (14) GraJen, N., and Svedberg, The, Biochem. D . C , at 4 0 cents each. Oil Co. announced. Construction began J., 34, 234 (1940). (15) Guthrie, J. D., Contrib. Boyce four months ago and continued Thompson Inst., 11, 29 night and day a t the greatest (1939). possible speed. The refinery was (16) Ibid., 11,261 (1940). originally expected t o start (17) Hartt, Constance E., Proc. large-scale production of highHawaiian Sugar Planters' Assoc. Rept. Comm. in quality toluene during t h e Charge Expt. Sta., 59, 113 middle of January. (1939), (pub. 1940). (18) Hitchcock, A. E., and ZimRepresenting an investment merman, P. W., Contrib. of over a half-million dollars, Boyce Thompson Inst., 11, the new plant introduces an 143 (1940). entirely new process. The plant (19) Horn, M. J., and Jones, D. B., J. Am. Chem. Soc, 62, a t Houston will produce over 234(1940). 2,000,000 gallons annually, from (20) Jacobsohn, K. P., and which i t is possible to produce Soares, M., Compt. rend. about 20,000,000 pounds of soc. biol., 133, 112 (1940). (21) Katz, M , et al., Natl. Re TNT. search Council (Canada), In addition to the present Bull. 815 (1939). method which is an extractive (22) Markwood, L. N., Science, rather than a synthetic process, 92, 204 (1940). Shell has perfected a second (23) Milbrath, J. Α., and Hartman, H., Ibid., 92, 401 process under which petroleum (1940). molecules are rearranged t o give (24) Miller, L. P., Ibid., 92, 42 toluene. B y utilizing the second (1940). process as a supplement to the (25) Nobécourt, P., Compt. rend. soc. biol., 133, 520 (1940). first, output can be boosted t o (26) Overstreet, R., and Broyer, 10,000,000 gallons of toluene per T. C., Proc. Nail. Acad. year, if necessary, from which an Sci., 26, 16 (1940). annual total of 100,000,000 (27) Ruben, S., Hassid, W. Z , and Kamen, M. D., pounds of T N T m a y be pro Science, 91, 578 (1940). duced. Shell's refineries in (28) Ruben, S., Kamen, M. D., other sections of the United Hassid, W. Z., and DeStates could increase this out Vault, D . C , Ibid., 90, U . 8 . DEPARTMENT OP A G R I C U L T U R E 570 (1939). put possibly to as much as 40,Pollen from alfalfa flower examined microscopically (29) Schlenker, F . S., Am. J. 000,000 gallons. for germinating power in the Bureau of Plant Industry Botany, 27, 5 2 5 (1940).
