Effect of Methyl and Ethyl Alcohol on the Growth of Barley Plants.

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1 Effect of Methyl and Ethyl Alcohol on the Growth of Barley Plants. BY AMAR NATH PURI, Rothamsted Experimental Station. With three Figures in the Text I. INTRODUCTION. I (" THYL alcohol is known to be highly toxic to the protoplasm of the J -* cells of the Elodea leaf (1). The effect is believed to be due in the main to increased permeability, which results in the exosmosis of the cell contents. Seifriz (2) has studied the antagonistic effect of salts on the toxicity of alcohol. The results show that, whereas calcium chloride never opposes the ill effects of ethyl alcohol on protoplasm, sodium chloride does act as an antagonizer, though not always completely. On the other hand, a combination of sodium chloride and calcium chloride acts unfailingly as an almost perfect inhibitor of the toxic influence of io per cent, alcohol. The toxicity of alcohol when" applied to the roots of plants has apparently not been studied. The object of this work was to see how far methyl and ethyl alcohol act as stimulants or poisons to barley plants, when added to the food solution in water-cultures. EXPERIMENTAL. Seeds were graded between 0-05 and c-o6 grm. The following concentrations of alcohol in the food solution were employed: Series. Ratio of alcohol to water : : i.oco 3. 1:5, : 25, :125, Control (Annals of Botany, VoL XXXVUL No. CLH. October, 3C 2

2 746 Puri. Effect of Methyl and Ethyl Alcohol The amounts of nutrient materials in the food solution were as follows: KNO 3 1 grm. MgSO KH 2 PO< 0.5 NaCl o-k FeCl To make up one litre. The water used in these experiments was distilled in a special still provided with a silver condenser (3). Each bottle contained about 600 c.c. of food solution, made up by adding 300 c.c. of nutrient solution of twice the strength given above, and 300 c.c. of alcohol solution, containing the necessary amount of alcohol. The experiments were conducted in triplicate, and the results with the two alcohols are presented separately. ETHYL ALCOHOL. Twelve days after placing the seedlings in the culture solutions, plants in Series 1 (cone. 1:200) appeared smaller than the rest; all others were normal and apparently of the same size, &c. Three weeks after, the plants in concentrations 1: 200 and 1 : 1,000 were practically dead and were thrown away. The growth in concentration 1:5,000 was distinctly impaired. In concentrations 1 :25,000 and 1 :125,000, except a faint suggestion that the roots were slightly smaller than those of the control plants, no ill effects were visible. During the next five weeks, plants supplied with alcohol, though healthy and normal, remained slightly shorter than the control. In another two weeks, however, all these plants made up the difference and grew in height equal to the control. After a further period of two weeks, these plants looked bigger than the control. It appeared, however, that this sudden growth was entirely confined to ear shoots, other leaves ceasing to grow, and showing signs of dying off. The ears looked just as good as, or perhaps better than those of the control plants. It seemed as if all the energy was being directed towards the production of ear shoots. It was noticed that in Series 3 and 4 (cone. 1 :5,000 and 1: 25,000) the roots were rather slimy at the tips. The above results suggest that, if alcohol be given to plants when they have grown up to a certain extent, it might have a.stimulating effect. This point was tested and the results are recorded in Part II of this investigation. The plants were taken out after twelve weeks, roots separated from shoots, and dried. Table I gives the average length of the roots and shoots, and their dry weights.

3 on l/ie Growth of Barley Plants. 747 fiej. Cottc. of i. ii : : I :i,ooo 3- : :5> o ] 4- i :35, I[ : 135, Control f ( / s TABLE Length in P I. in. 3I-O / y 1 Dry weight a-55 FIG. 1. Average dry weights and lengthi of Barley plants grown in nutrient solutions with different concentrations of ethyl alcohol. 1 > (grm. Shoot H-I5 The above results are shown graphically in Fig. 1. There is an indication of stimulation in very small concentrations. The lengths of the plants do not show any marked difference in the roots. The extra length of the shoots in Series 3 (cone. 1:5,000) emphasizes the fact, pointed out before, that the lower toxic doses of ethyl alcohol tend to push forward the development of ear shoots at the expense of the vegetative leaves, so that, although the average length of plants was greater than the control, their dry weights were smaller. It will be seen that alcohol in concentrations 1:1.000 and higher is fatal to barley plants, as is apparent from the death of all the plants in Series 1 and 2 within three week9. It was also noticed that when plants were killed by these high concentrations the dead roots

4 748 Puri. Effect of Methyl and Ethyl Alcohol and the surface of the solution were infested with copious growth of moulds. METHYL ALCOHOL. A set of experiments, similar to the above, was carried out with methyl alcohol, the strength of solutions and other conditions being the same as in the case of ethyl alcohol. The average length of roots and shoots, as well as their dry weights, are recorded in Table II and shown graphically in Fig. a. t~ies. I Cone, of i : 3oo i : 1,000 i : 5,000 1 :35,000 1 :135,000 Control am K 9 7 t 3 3 A TABLE II. Length (inches) Shoot V A <3 (A 1 V 1 ^ g S? 5 g a? Dry weight {grm.) 1.(So 7-3O O FIG. 3. Average dry weights and lengths of barley plants grown in nutrient solutions with different concentrations of methyl alcohol. The essential differences between the effect of methyl and ethyl alcohol were: (1) Plants grew in the presence of methyl alcohol concentrations up to 1 : 300, though in higher concentration the growth was stunted ; while in

5 on the Growth of Barley Plants. 749 the case of ethyl alcohol concentration of 1:1,000 was found to be fatal. This would seem to show that ethyl alcohol is more toxic than methyl alcohol. This result is in agreement with that of Vandevelde (4), who studied the toxic effects of various alcohols on the cells of the red onion, and found that the poisonous nature of the monohydric alcohols increases with the molecular weight. (a) In higher concentrations, ethyl alcohol favoured the growth of ear shoots and the suppression of vegetative leaves, whereas methyl alcohol favoured the growth of leaves and not the ear shoots. This difference in the behaviour of the two alcohols is extremely interesting and difficult to account for. The difference between the physico-chemical properties of the two alcohols is so small that any explanation based on their effect on the permeability of cell-walls would be difficult to picture; cf. Seifriz (2). It may be noted that there seems to be no other parallel instance of two substances, so much alike in chemical constitution as the alcohols, showing a radical difference not only in the degree of toxicity but its type. II. EFFECT OF ADDING ETHYL ALCOHOL TO BARLEY PLANTS AT DIFFERENT STAGES OF GROWTH. It was pointed out in the earlier part that barley plants supplied with alcohol showed a very rapid growth after a certain time. In order to elucidate further information with regard to this observation three sets of experiments consisting of forty plants each were employed. Set A. Alcohol added from the beginning. Set B. Alcohol added after three weeks of growth. Set C. Alcohol added after six weeks of growth. The following concentrations of ethyl alcohol were employed : 1. 1: :1, :5, :25, :125, :250, :500, Control. The experimental method and technique were the same as in the earlier work. The general conclusions in Set A, where alcohol was added from the beginning, were the same as in the previous experiments, except that plants in concentrations 1 : i.ooo, although they only developed

6 75 Puri. Effect of Methyl and Ethyl AlcoJwl a single weakly shoot with little leaf growth, managed to struggle through, while previously they had all died. The suggestion that alcohol might act as a stimulant when given to plants at advanced stages of growth was not confirmed. It was observed, however, that plants can partly resist the poisonous action of alcohol when they are grown up to a certain extent. It is interesting to compare this result with that of Vandevelde (4), who found that older cells withstand the action of the alcohols better than the younger. Brenchley (5), who studied the toxic effect of phenols on barley plants, also concluded that, when once growth is fairly under way and vigorous, the plant can cope with a strength of poison which is most deleterious at an earlier stage of development. Plants were kept in the culture solution for ten weeks, after which they were taken out, dried, and weighed. The mean dry weights of the various plants, along with the probable error, are given in Table III. I Set A. Cone, of I. 1 : [ : 1, =5, t : 35, =125, t : 250, [ : 500, ( Control i. i 3. I 3- i 4- i 5- i 6. i 7- ' Cone, of I : 3oo i: i.ooo 1:5;0O0 i: 35,000 I :135,000 1 : 350, ,000 Control TABLE III. Alcohol added from thi beginning I-II 1-03 O-I3I OO96 O-002 O.OBI O.IO Set B. Alcohol added after three weeks l &066 l-oo o-3h O-3O8 5-" oi O-359 Set C. Alcohol added after six weeks. Cone, of = 2OO : 1,000 : 5,000 = 35,000 =135, Control :350,000 ] : 500, I-II O-0O2 O-O O-I O-437 O O O '

7 on the Growth of Barley Plants I Control. i-soaooo 1:250,000 rizs.000 I 2&000 1:5.000 I-1X100 Control 1:500X100 r.bsoxjoo 1:125,000 /:25,000 ;:5000 1:1,000 Control V.5O0.000 I.250XJOO 1)25, ,000 / :1000 r.zoo FIG. 3. Average dry weights, of three series of barley plants grown in nutrient solutions with different concentrations of ethyl alcohol added at different stages of growth, A. Alcohol added at the beginning. B. Alcohol added after three weeks, a Alconol added after six weeks. i

8 752 Puri. Effect of Methyl and Ethyl Alcolwl on Barley Plants. The above results are graphically represented in Fig. 3 and bring out very clearly the conclusion that the toxic effect of alcohol is appreciably reduced when it is administered at a later stage of growth. It will be seen that in Set A the poisonous action appeared in concentrations 1 : 3.5,000 and higher, while in Set B it is noticeable at concentrations 1 : 1,000 and higher ; whereas in Set C it is observed only in concentration 1:200 to an appreciable extent. It may be concluded from the foregoing results that when the plant is developed to a certain extent it can resist the action of poison much better than in the earlier stages of growth. In studying the toxic effect of substances, therefore, it is necessary to pay due regard to the age of the plant when the poison is first administered. SUMMARY. 1. Ethyl alcohol is more toxic to barley plants than is methyl alcohol. 2. The difference in the toxicity of the two alcohols is not only one of degree, but of kind ; ethyl alcohol favours the growth of ear shoots and the suppression of vegetative leaves, while methyl alcohol favours the growth of leaves and not that of the ear shoots. 3. Plants in their later stages of growth can withstand the toxic action of ethyl alcohol much better than earlier in life. The work here described was carried out under the direction of Dr. W. E. Brenchley, and it is my pleasant duty to record my thanks to her for the facilities provided me, and for many valuable suggestions. My acknowledgements are also due to the Punjab Drainage Board for the grant of the scholarship which gave me the opportunity of undertaking this work. REFERENCES. 1. SEIFRIZ, W. : Observations on the Reaction of Protoplasm to some Reagents. Ann. Bot, xxxvii, p. 489, : Antagonistic Effect of Salts on Toxicity of Bot. Gazette, Ixxvi, p. 397, 3. BRENCHLEY, W. E. : Inorganic Plant Poisons and Stimnlants, pp VANDEVELDE, A. J. J.: Plasniolysis, Determination of the Toxicity of Alcohols. Chem. Centr., 1900, i. 781; from Handb. v. iii, Vlaamsch Nat Geneesknndig Congres, Antwerp, 1S BRENCHLEY, W. E. : Organic Plant Poisons. II. Phenols. Ann. Bot, ixxii, p. 359, 1918.

Push down hard on the cover slip, but do not push the cover slip sideways

Push down hard on the cover slip, but do not push the cover slip sideways Q1.A student investigated mitosis in the tissue from an onion root tip. (a) The student prepared a temporary mount of the onion tissue on a glass slide. She covered the tissue with a cover slip. She was