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Growth, productivity and compositional contents of bean (Vicia faba) seeds as affected by different night-temperatures
Flora, Abt. A, Bd. 158, S. 569-576 (1967) Plant Metabolism and Growth Regulators Unit National Research Centre Dokki, Cairo, U.A.R.
Growth, productivity and compositional contents of bean (Vicia faba) seeds as affected by different night-temperatures By H. SAID, T. HEGAZY and R. M. IMAM With one figure in the text (Received September 20, 1967)
Summary Higher night-temperatures had an accelerating effect on stem elongation, but as the plants get older this effect seemed to disappear and optimum night-temperature for stem elongation shifteddown wards. Flowering was delayed in plants grown under non-fluctuating temperature as well as under low night-temperature. The highest yield of bean seeds was obtained at 10°C. night-temperature treatment. The carbohydrate and nitrogen contents of bean seeds were maximum at 10°C. night-temperature treatment and minimum at 20 °C. night-temperature.
-
Introduction
-
.
,
,
Many investigators have reported that plant growth was found to be affected by temperature changes (IVANOV 1935; ULRICH 1956; KURKI and WITTWER 1957; and DMITRENKO 1962). WENT (1944), found that the rate of stem elongation is a sensitive indicator for the effects of different temperatures on plants and changes immediatly upon changes of temperature. VIGLIERCHIO and WENT (1957), found that the stem elongation of Phaseolus vulgaris increases with higher night-temperatures during the early stages of development, but as the plants became older, the optimum night-temperature shifts down-words. Similar results have been reported by EVANS (1957), through his work on bean plants. Night-temperature is the most critical factor influencing plant flowering. Thus, DE RAFOLS (1953), found that at constant temperature of 17 DC, the first flowering of rubber bearing plant appeared 4 months after sowing, but at 20°C day and 11 °C night-temperatures flowering began 45 days after sowing. AITKEN (1955), found that, for all varieties of subterranean clover, flower initiation was accelerated by insufficient period of low temperature. KURKI and WITTWER (1957), WITTWER and TEUBNER (1957), found that for tomato plants, a low night-temperature increased the number of days to the first open flower and decreased the number of leaves. On the other hand, KNIGHT and HOLLOWELL (1958), dealing with crimson clover found that high night-temperatures inhibited flower production when plants were grown from germination to maturity under the same temperature treatment. 39
Flora, A bt. ,\, Ed. 158.
570
H. SAID, T. HEGAZY and R. M. IMAM
With regard to the effect of temperature on plant yield, ALBAN (1951), studying the effect of different night-temperature on yield and maturity of green house tomatoes found that with high night-temperature, smallest fruits were obtained while with low night-temperature good yield was obtained. TUKEY (1952), found that increase in night-temperature at earlier stages of growth accelerated fruit development of sour cherry and inhibited it during later stages. On the other hand, many investigators reported reduction in the yield of seeds of many plants as a result of exposure to high temperatures (MEDERSKI and JONES 1963, SEMENIUK and STEWART 1963). The importance of this study is due to two main reasons, the first one is the importance of the plant as a field crop, and the second one is the great variations between maximum and minimum limits of temperature along the NILE VALLEY.
Methods Uniform-sized seeds of a hybrid (Giza "2") bean (Ficia (aba) were soaked in tap witter in the dark for 24 hours at room temperature (about 20°C.), selected for uniformity by choosing those between 1 and 3 mm. length of sprouted radicle. These uniform germinated seeds were then planted (1 seed per pot) at a constant depth of about 3 em. in uniformly washed sand supplied with ROBBIN'S (1946) nutrient solution. After the addition of 150 mI. nutrient solution, the pots were transferred to the conditioned cabinents adjusted at 5, 10, 15 and 20°C. as night-temperatures and 20 °e. day temperature. Light supply inside these chambers is fulfiled by means of 40 watt day-light fluorescent lamps. The maximum light intensity measured at the centre of each chamber was 5000-6000 lux. The length of both dark and light periods was kept constant, being 12 hours for each. Watering was earried out regularly every two days using ROBBIN'S nutrient solution. :\1.easurements of stem length were carried out at definite physiological stages namely at the 2nd, 4th., 6th. and 8th. leaf stages. The date of flower initiation for each treatment was determined, and the time required for all the plants of each treatment to set on flowers W,tS counted. By the end of the period of flowering and fruit set (three months after planting), the pots were transferred to the Botanical garden of the National Research Centre till maturity. For harvest, the pods of each plant, which was considered as a replicate, were collected together. For each replicate plant, shoot height, number of pods and seeds, weight of pods and seeds were determined. The seed coat was mechanically removed, the seeds were ground thoroughly by a microgrinding mill, and the fine dry powder was used for the determination of different nitrogen and carbohydrate contents. The methods used for carbohydrate determinations have been referred to in previous papers (SAID 1941, 1945). Nitrogen determinations were carried out according to the methods discussed by SAID and EL-SHISHINY (1944). The results were analysed statistically according to the simple analysis of variance ("F" test). The values of least significant differences (L.S.D.) were obtained whenever the calculated "F" values were significant at 5 % level of probability.
Growth, productivity and compositional contents of bean etc,
571
Results
Growth Mea~urements: Stem length It is clear from Fig, (1) that high night-temperature has an accelerating effect on stem elongation at early stages of growth, Thus at the 2nd and 4 th leaf-stages, plants grown at 20°/20 °C, as day/night temperatures (without diurnal fluctuation of temperature) showed the highest value of stem length, while lower night-temperatures resulted in shorter plants, At later stages of growth (6th and 8th leaf-stages) the accelerating effect of high night-temperature on stem elongation seemed to stop the optimum night-temperature shifts down-wards,
Mature Stage: Shoot height Statistical analysis of the data illustrated in table I shows that growth of plants under high night-temperatures (15 and 20°C.) resulted in significant decreases in shoot hight as compared with plants grown at low night-temperatures (5 and 10 DC.). Plants grown at 15 DC. and 20 DC. night-temperatures do not differ significantly in their shoot height. This is also the case for plants grown at 5 and 10 DC. night-temperatures treatments. SO It5 I-
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STAOES OF GROWTH Fig. L The effect of different temperatures on stem length of bean plants at different physiological stages. 39*
H. SAID, T. HEGAn and R. M.
572
Growth ,wd Yield Determinations of Bean (Vicia faba) plants as affected by different night-temperatures
Table I
Treatments
5°C. 10°C. 15 DC. 20°C.
IMA:I'[
Night-temp. Night-temp. Night-temp. Night-temp.
L.S.D. (5%)
Shoot Height
No. of Date of flowering 1 ) podsjp1.2)
89.69 96.06 82.69 78.31
46.1 43.6 38.5 50.0
6.84
2.1
4.4 4.2 4.1 3.6
Wt. of podsjpl.
No. of seedsjpl.
Wt. of seedsjpl.
7.48 11.60 10.34 6.02
9.6 10.2 9.9 6.01
5.98 8.99 7.76 4.00
2.38
1.74
1.55
') Calculated in days from date of sowing to the 1st flower bud initiation. 2) "F" calculated not significant.
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Date of flowering It is clear from table I that flowering time of bean plants was greatly affected by different night-temperatures. Night-temperature of 15 DC. induced earlier flowering. Lower night-temperatures resulted in retardation of flower initiation, more retardation occurred where no diurnal fluctuation of temperature existed.
Weight and number of pods It is clear from table I that differences in pod number due to different nighttemperatures are statistically non-significant. On the other hand, night-temperatures resulted in significant differences in weight of pods. Although plants grown at 10 and 15 DC. night-temperatures showed non-significant diffeI'ences in weight of pods yet higher and lower night-temperatures caused significant decrease in weight of pods. Weight and number of seeds Table I shows that plants grown at 5, 10 and 15 DC. night-temperatures produced nearly the same number of seeds per plant. Plants grown at 20 DC. nighttemperature showed the lowest number of seeds per plant. Significant differences exist between 20 DC. night-temperature and each of the other night-temperatures, so we may conclude that high seed production in bean plants need daily fluctuating temperatures but not constant one. On the other hand, no significant difference exists in weight of seeds between plants grown at 10 and 15 DC. night-temperatures. Higher and lower night-temperatures resulted in significant decreases in weight of seeds.
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Growth, productivity and compositional contents of bean etc.
573
Chemical Analysis of the Seeds: Carbohydrate Contents Soluble sugars content It is clear from table II that bean seeds contained very small amounts of reducing sugars while sucrose contents were found in adequate amounts. Seeds produced at 10°C. night-temperature contained the highest amounts of reducing sugars. For sucrose content, plants grown at 10 °C. night-temperature produced seeds containing the greatest amount of this carbohydrate fraction. Higher night-temperatures resulted in a considerable decrease in the sucrose content of bean seeds. No significant differences exist between seeds produced at 10 and 5°C. night-temperatures, and between 15°C. night-temperatures in their sucrose content.
Polysaccharide contents Table II shows that this fraction is the main carbohydrate constituent of bean seeds. Growth of bean plants at 10 and 20 °C. night-temperatures produced seeds with the greatest and least amounsts of this carbohydrate fraction respectively.
Table II
Average values of carbohydrate fractions of bean seeds (mgm. glucose/plant) at different night-temperatures Treatments
Glucose
Sucrose
Polysaccha.
5 DC. Night-temp. 10 DC. Night-temp. 15 DC. Night-temp. 20 DC. Night-temp.
1.28
154.29
2.36 1.42 1.Ui
178.15 137.57 56.84
2741.8.'> 4070.84 2811.01 1596.78
L.S.D. (5%)
0.49
37.21
523.58
1-
:s
"
g
:e
Nitrogenous contents: Total nitrogen content Table III shows that growing bean plants under 5, 10 and 15°C. night-temperatures produced seeds that do not differ significantly in the amounts of their total nitrogen content. Seeds produced at 20°/20 °C. as day/night temperatures contained the least amount of total-nitrogen content which differ significantly from the amounts obtained with other night-temperatures.
574
R.
Table III
SAID, T.
REGAZY
and R. M. IMAM
Average values of nitrogen fractions of bean seeds (mgm. Njplant) at different nighttemperatures Treatments 5°C. 10°C. 15 °C. 20°C.
Night-temp. Night-temp. Night-temp. Night-temp.
L.S.D. (5%)
Tot-N.
Sol. N.
Prot. N.
335.41 421.83 375.30 177.86
52.18 64.45 48.72 21.15
283.23 354.04 326.58 156.71
91.75
15.92
80.14
The behaviour of soluble - and protein - nitrogen: The soluble - nitrogen contents of bean seeds produced at 5 and 10°C. nighttemperatures show non-significant differences. Seeds produced at 200/20°C. as day/night-temperatures, where no diurnal fluctuation in temperature existed, contained the least amount of soluble-nitrogen. It is clear from table III that seeds produced at 20°C. night-temperature contained the least amount of protein nitrogen content which is about 50 % of these found with other night-temperature treatment. No significant differences are detected in the protein-nitrogen content of seeds produced at 5, 10 and 15°C. nighttemperatures. Discussion
Concerning the effect of night-temperature on stem elongation, the results showed that at early stages of growth (2nd and 4th leaf-stages) the highest nighttemperature (20°C.) was the optimum one for stem elongation, while at later stages (6th and 8th leaf-stages), 10°C. night-temperature became the optimum one. At maturity, shoot height measurements showed the same behaviour towards different night-temperatures as at the 8th leaf-stage. This downwards shift of the optimal night-temperature as the plants became older was observed by many investigators (cf. WENT 1945; EVANS 1957; and VIGLIERCHIO and WENT 1957). It was mentioned in the introduction that many workers observed that constant temperature delays flowering while diurnal fluctuating temperatures accelerate flower differentiation and emergence (cf. THOMPSON 1929; DE RAFOLS 1953; HIESEY 1953; and KNIGHT and HOLLOWELL 1958). The results of this experiment add further support to this conclusion, since growth of bean plants at 20°-20°C as day/night temperatures delayed flowering. Moreover, it was observed from the data that flower initiation of bean plants was accelerated by a period of low temperature during night. In this connection, it may be mentioned that AITKEN (1955), found that flower initiation for all varieties of subterranean clover was accelerated by a period of low temperature.
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-
-
-
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-
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Growth, productivity and compositional contents of bean etc.
575
The results of yield determinations obtained from this work showed clearly that there was no significant change in the number of pods per plant as a result of different night-temperature treatments. From this result we may conclude that night-temperature had no effect on the number of flowers setting pods. On the other hand, weight of pods was significantly decreased in bean plants grown at night-temperatures below or above the optimum temperatures. In this connection it may be mentioned here that many workers reported reductions in the yield of seeds of many plants as a result of exposure to high temperatures (cf. MILTHORPE and HOROWITZ 1943; MEDERSKI and JONES 1963; SEMENIUK and STEWART 1963). The number and weight of seeds per plant were found to be significantly decreased by high night-temperature. It is worthy to note here that plants grown at 5, 10 and 15 DC. night-temperatures produced more or less the same number of seeds. On the other hand, growth at 5 DC., night-temperature resulted in significant decreases in the weight of bean seeds as compared with growth at 10 and 15 DC. night-temperature trements. In this connection, EVANS (1957), working on beans, found that lowering the temperature of growth not only increased the number of mature pods per plant, but also tended to increase the number and size of seeds in each pod. The analysis of bean seeds for their total-nitrogen contents revealed that subjection of bean plants to diurnal fluctuation in temperature during growth, resulted in significant increases in the total-nitrogen contents of the seeds. On the other hand, growth of plants under night-temperatures of 5, 10 and 15 DC. resulted in non-significant differences in the amounts of total-nitrogen of the seeds. The soluble-nitrogen contents of the seeds obtained from plants grown under lower night-temperatures were significantly more than those found in seeds of plants grown under high nighttemperature. The protein-nitrogen contents of the seeds were found to be correlated with the results obtained for total-nitrogen content. On the whole, we may conclude that a fluctuation of day and night-temperahues resulted in significant increases in all nitrogen constituents of the seeds. The decrease in nitrogenous contents of bean seeds observed at high night-temperature may be attributed to either decreased absorption of nitrogen compounds from the soil or to a decrease in the rate of nitrogen assimilation. The analysis of bean seeds for their carbohydrate contents revealed that reducing sugars are nearly absent and the main soluble sugar found was sucrose. It was found that plants grown at lower night-temperatures produced seeds containing more amounts of sucrose than those of plants grown at higher night-temperatures. In this connection it may be mentioned here that ITo and TAKEDA (1963), found that sugar contents of sugar beet were highly increased with low temperatures. Polysaccharides were found to be the main carbohydrate constituent of bean seeds. The analysis of seeds for their polysaccharide contents revealed that daily temperature fluctuation significantly increased this carbohydrate fraction. Maxi-
576
H. SAID, T. HEGAZY and R. M. IMAM
mum increase in the polysaccharide was found in seeds produced by plants grown at 10°C. night-temperature. It is worthy to note here that growth of bean plants at 20-20 DC. as day and night-temperatures produced seeds with the least amount of polysaccharide content .. Literature . AITKEN, Y., 1955. Australian Jour. Agric. Rec. 6 (2), 212-244. - 1955. Ibid. 6 (2), 258-264. ALBAN, E. K.; 1951. Market Growers Journ. 80 (3), 9, 10, 28, 29. cf. Biolog. Abs. 19793. DE RAFOLS, W., 1956. An Inst. Aac. Invest. Agron (Madrid), 2 (1), 3-52, cf. BioI. Abs. 19440 (1954). DMITRENKO, V. P., 1962. Tr. Ukrain. Nauchn. Issled. GidrometeoroL Inst. 28, 13-23, Referat. Zhur., BioI., 1962, No. 23 G. 217. cf. Biolog. Abs. 3196 (1964). EVANS, L. T., 1957. Experimental control of plant growth, P. 124-128. The Ronald press company. HIESEY, W. M., 1953. Amer. Jour. Bot. 40 (4), 205-22l. ITO, K., and TAKEDA, T., 1964. Proc. Crop. Sci. Soc. Japan, 31 (3), 272-276 (1963), cf. Biolog. Abs.30297. IVANOV, S. M., 1935. Bull. AppL Bot., Genet. and Plant-Breed. Ser., 36, Russ. 163-198, cf. Biolog. Abs. 9326 (1937). KNIGHT, W. E., and HOLLOWELL, E. A., 1958. Agrom. Jour. 60 (6), 295-298. KURKI, L., and WITTWER, S. H., 1957. Maataloustieteellinen Aikakauskirja, 28 (4), 223-228. l\hDERSKI, H. J., and JONES, J. B. jr., 1963. Soil Sci. Soc. Amer. Proc. 27 (2), 186-189 cf. Biolog. Abs. 6940 (1955). l\iILTHORP, F. L., and HOROWITZ, B., 1943. Agric. Gaz. N.S. Wales, 64, 53-57. ROBBIN'S, W. R., Sand and water culture methods used in the study of nutrition, P. 86. Commonwealth Agricultural Bureaux England. SAID, H., 1941. Bull. Fac. Sci. Fonad I Univ., Cairo 24, 13. - 1945. Ibid. £0, 117. - and EL-SHISHINY, E. D. H., 1944. Plant PhysioL 19 (4), 660-670. SEMENIUK, P., and STEWART, R. N., 1963. Prac. Amer. Soc. Hart. Sci., 82, 583-686 cf. Biolog. Abs. 7926 (1964). THOMPSON, H. C., 1929. Proc. Internat. Congress Plant Sci. Ithaca, N. Y. 1926, 2, 1070. TUKEY, L. D., 1962. Bot. Gaz. 114 (2), 165-166. ULRICH, A. J., 1956. Jour. Amer. Soc. Sugar Beet TecbnoL 9 (2),97-108, cf. Biolog. Abs. 12335 (1960). VIGLIERCHIO, D. R., and WENT, F. W., 1957. Amer. Journ. Bot. 44, (5), 449-453. WENT, F. W., 1944. Amer. Journ. Bot. 31 (10), 597-618. - 1945. Ibid. 32 (8), 469-479. _ and ENGELSBERG, R., 1946. Arch. Biochem. 9, 187-200, cf. Ann. Rev. Plant. PhysioL 4, 347-362 (1963). WITTWER, S. R., and TEUBNER, F. G., 1957. Amer. Journ. Bot. 44 (2), 126-129. Author's address: Dr. H. SAID, Prof. of Plant Physiology, Cairo University; Dr. T. HEGAZY, Prof. of Plant Physiology, N.R.C.; R. M. IMAM, Research Assistant, Plant Metabolism Unit, N.R.C., National Research Centre, Sh. el-Tahrir, Cairo-Dokki (Egypt).
Growth, productivity and compositional contents of bean (Vicia faba) seeds as affected by different night-temperatures By H. SAID, T. HEGAZY and R. M. IMAM With one figure in the text (Received September 20, 1967)
Summary Higher night-temperatures had an accelerating effect on stem elongation, but as the plants get older this effect seemed to disappear and optimum night-temperature for stem elongation shifteddown wards. Flowering was delayed in plants grown under non-fluctuating temperature as well as under low night-temperature. The highest yield of bean seeds was obtained at 10°C. night-temperature treatment. The carbohydrate and nitrogen contents of bean seeds were maximum at 10°C. night-temperature treatment and minimum at 20 °C. night-temperature.
-
Introduction
-
.
,
,
Many investigators have reported that plant growth was found to be affected by temperature changes (IVANOV 1935; ULRICH 1956; KURKI and WITTWER 1957; and DMITRENKO 1962). WENT (1944), found that the rate of stem elongation is a sensitive indicator for the effects of different temperatures on plants and changes immediatly upon changes of temperature. VIGLIERCHIO and WENT (1957), found that the stem elongation of Phaseolus vulgaris increases with higher night-temperatures during the early stages of development, but as the plants became older, the optimum night-temperature shifts down-words. Similar results have been reported by EVANS (1957), through his work on bean plants. Night-temperature is the most critical factor influencing plant flowering. Thus, DE RAFOLS (1953), found that at constant temperature of 17 DC, the first flowering of rubber bearing plant appeared 4 months after sowing, but at 20°C day and 11 °C night-temperatures flowering began 45 days after sowing. AITKEN (1955), found that, for all varieties of subterranean clover, flower initiation was accelerated by insufficient period of low temperature. KURKI and WITTWER (1957), WITTWER and TEUBNER (1957), found that for tomato plants, a low night-temperature increased the number of days to the first open flower and decreased the number of leaves. On the other hand, KNIGHT and HOLLOWELL (1958), dealing with crimson clover found that high night-temperatures inhibited flower production when plants were grown from germination to maturity under the same temperature treatment. 39
Flora, A bt. ,\, Ed. 158.
570
H. SAID, T. HEGAZY and R. M. IMAM
With regard to the effect of temperature on plant yield, ALBAN (1951), studying the effect of different night-temperature on yield and maturity of green house tomatoes found that with high night-temperature, smallest fruits were obtained while with low night-temperature good yield was obtained. TUKEY (1952), found that increase in night-temperature at earlier stages of growth accelerated fruit development of sour cherry and inhibited it during later stages. On the other hand, many investigators reported reduction in the yield of seeds of many plants as a result of exposure to high temperatures (MEDERSKI and JONES 1963, SEMENIUK and STEWART 1963). The importance of this study is due to two main reasons, the first one is the importance of the plant as a field crop, and the second one is the great variations between maximum and minimum limits of temperature along the NILE VALLEY.
Methods Uniform-sized seeds of a hybrid (Giza "2") bean (Ficia (aba) were soaked in tap witter in the dark for 24 hours at room temperature (about 20°C.), selected for uniformity by choosing those between 1 and 3 mm. length of sprouted radicle. These uniform germinated seeds were then planted (1 seed per pot) at a constant depth of about 3 em. in uniformly washed sand supplied with ROBBIN'S (1946) nutrient solution. After the addition of 150 mI. nutrient solution, the pots were transferred to the conditioned cabinents adjusted at 5, 10, 15 and 20°C. as night-temperatures and 20 °e. day temperature. Light supply inside these chambers is fulfiled by means of 40 watt day-light fluorescent lamps. The maximum light intensity measured at the centre of each chamber was 5000-6000 lux. The length of both dark and light periods was kept constant, being 12 hours for each. Watering was earried out regularly every two days using ROBBIN'S nutrient solution. :\1.easurements of stem length were carried out at definite physiological stages namely at the 2nd, 4th., 6th. and 8th. leaf stages. The date of flower initiation for each treatment was determined, and the time required for all the plants of each treatment to set on flowers W,tS counted. By the end of the period of flowering and fruit set (three months after planting), the pots were transferred to the Botanical garden of the National Research Centre till maturity. For harvest, the pods of each plant, which was considered as a replicate, were collected together. For each replicate plant, shoot height, number of pods and seeds, weight of pods and seeds were determined. The seed coat was mechanically removed, the seeds were ground thoroughly by a microgrinding mill, and the fine dry powder was used for the determination of different nitrogen and carbohydrate contents. The methods used for carbohydrate determinations have been referred to in previous papers (SAID 1941, 1945). Nitrogen determinations were carried out according to the methods discussed by SAID and EL-SHISHINY (1944). The results were analysed statistically according to the simple analysis of variance ("F" test). The values of least significant differences (L.S.D.) were obtained whenever the calculated "F" values were significant at 5 % level of probability.
Growth, productivity and compositional contents of bean etc,
571
Results
Growth Mea~urements: Stem length It is clear from Fig, (1) that high night-temperature has an accelerating effect on stem elongation at early stages of growth, Thus at the 2nd and 4 th leaf-stages, plants grown at 20°/20 °C, as day/night temperatures (without diurnal fluctuation of temperature) showed the highest value of stem length, while lower night-temperatures resulted in shorter plants, At later stages of growth (6th and 8th leaf-stages) the accelerating effect of high night-temperature on stem elongation seemed to stop the optimum night-temperature shifts down-wards,
Mature Stage: Shoot height Statistical analysis of the data illustrated in table I shows that growth of plants under high night-temperatures (15 and 20°C.) resulted in significant decreases in shoot hight as compared with plants grown at low night-temperatures (5 and 10 DC.). Plants grown at 15 DC. and 20 DC. night-temperatures do not differ significantly in their shoot height. This is also the case for plants grown at 5 and 10 DC. night-temperatures treatments. SO It5 I-
~~
'to
~
35 I-
~
30
a:;
25 I-
(!)
-.J
~ h:
NIGHT TEt'fR
e
10 0 :':J
20 15 I-
V:> 10 .5 l-
0
t,f°C
.1'7~ 20°C
It!'
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5°C
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2 nd
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8 til LEAF
STAOES OF GROWTH Fig. L The effect of different temperatures on stem length of bean plants at different physiological stages. 39*
H. SAID, T. HEGAn and R. M.
572
Growth ,wd Yield Determinations of Bean (Vicia faba) plants as affected by different night-temperatures
Table I
Treatments
5°C. 10°C. 15 DC. 20°C.
IMA:I'[
Night-temp. Night-temp. Night-temp. Night-temp.
L.S.D. (5%)
Shoot Height
No. of Date of flowering 1 ) podsjp1.2)
89.69 96.06 82.69 78.31
46.1 43.6 38.5 50.0
6.84
2.1
4.4 4.2 4.1 3.6
Wt. of podsjpl.
No. of seedsjpl.
Wt. of seedsjpl.
7.48 11.60 10.34 6.02
9.6 10.2 9.9 6.01
5.98 8.99 7.76 4.00
2.38
1.74
1.55
') Calculated in days from date of sowing to the 1st flower bud initiation. 2) "F" calculated not significant.
On
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Date of flowering It is clear from table I that flowering time of bean plants was greatly affected by different night-temperatures. Night-temperature of 15 DC. induced earlier flowering. Lower night-temperatures resulted in retardation of flower initiation, more retardation occurred where no diurnal fluctuation of temperature existed.
Weight and number of pods It is clear from table I that differences in pod number due to different nighttemperatures are statistically non-significant. On the other hand, night-temperatures resulted in significant differences in weight of pods. Although plants grown at 10 and 15 DC. night-temperatures showed non-significant diffeI'ences in weight of pods yet higher and lower night-temperatures caused significant decrease in weight of pods. Weight and number of seeds Table I shows that plants grown at 5, 10 and 15 DC. night-temperatures produced nearly the same number of seeds per plant. Plants grown at 20 DC. nighttemperature showed the lowest number of seeds per plant. Significant differences exist between 20 DC. night-temperature and each of the other night-temperatures, so we may conclude that high seed production in bean plants need daily fluctuating temperatures but not constant one. On the other hand, no significant difference exists in weight of seeds between plants grown at 10 and 15 DC. night-temperatures. Higher and lower night-temperatures resulted in significant decreases in weight of seeds.
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W
Ta
N
tu
11
tb
01
t f t
Growth, productivity and compositional contents of bean etc.
573
Chemical Analysis of the Seeds: Carbohydrate Contents Soluble sugars content It is clear from table II that bean seeds contained very small amounts of reducing sugars while sucrose contents were found in adequate amounts. Seeds produced at 10°C. night-temperature contained the highest amounts of reducing sugars. For sucrose content, plants grown at 10 °C. night-temperature produced seeds containing the greatest amount of this carbohydrate fraction. Higher night-temperatures resulted in a considerable decrease in the sucrose content of bean seeds. No significant differences exist between seeds produced at 10 and 5°C. night-temperatures, and between 15°C. night-temperatures in their sucrose content.
Polysaccharide contents Table II shows that this fraction is the main carbohydrate constituent of bean seeds. Growth of bean plants at 10 and 20 °C. night-temperatures produced seeds with the greatest and least amounsts of this carbohydrate fraction respectively.
Table II
Average values of carbohydrate fractions of bean seeds (mgm. glucose/plant) at different night-temperatures Treatments
Glucose
Sucrose
Polysaccha.
5 DC. Night-temp. 10 DC. Night-temp. 15 DC. Night-temp. 20 DC. Night-temp.
1.28
154.29
2.36 1.42 1.Ui
178.15 137.57 56.84
2741.8.'> 4070.84 2811.01 1596.78
L.S.D. (5%)
0.49
37.21
523.58
1-
:s
"
g
:e
Nitrogenous contents: Total nitrogen content Table III shows that growing bean plants under 5, 10 and 15°C. night-temperatures produced seeds that do not differ significantly in the amounts of their total nitrogen content. Seeds produced at 20°/20 °C. as day/night temperatures contained the least amount of total-nitrogen content which differ significantly from the amounts obtained with other night-temperatures.
574
R.
Table III
SAID, T.
REGAZY
and R. M. IMAM
Average values of nitrogen fractions of bean seeds (mgm. Njplant) at different nighttemperatures Treatments 5°C. 10°C. 15 °C. 20°C.
Night-temp. Night-temp. Night-temp. Night-temp.
L.S.D. (5%)
Tot-N.
Sol. N.
Prot. N.
335.41 421.83 375.30 177.86
52.18 64.45 48.72 21.15
283.23 354.04 326.58 156.71
91.75
15.92
80.14
The behaviour of soluble - and protein - nitrogen: The soluble - nitrogen contents of bean seeds produced at 5 and 10°C. nighttemperatures show non-significant differences. Seeds produced at 200/20°C. as day/night-temperatures, where no diurnal fluctuation in temperature existed, contained the least amount of soluble-nitrogen. It is clear from table III that seeds produced at 20°C. night-temperature contained the least amount of protein nitrogen content which is about 50 % of these found with other night-temperature treatment. No significant differences are detected in the protein-nitrogen content of seeds produced at 5, 10 and 15°C. nighttemperatures. Discussion
Concerning the effect of night-temperature on stem elongation, the results showed that at early stages of growth (2nd and 4th leaf-stages) the highest nighttemperature (20°C.) was the optimum one for stem elongation, while at later stages (6th and 8th leaf-stages), 10°C. night-temperature became the optimum one. At maturity, shoot height measurements showed the same behaviour towards different night-temperatures as at the 8th leaf-stage. This downwards shift of the optimal night-temperature as the plants became older was observed by many investigators (cf. WENT 1945; EVANS 1957; and VIGLIERCHIO and WENT 1957). It was mentioned in the introduction that many workers observed that constant temperature delays flowering while diurnal fluctuating temperatures accelerate flower differentiation and emergence (cf. THOMPSON 1929; DE RAFOLS 1953; HIESEY 1953; and KNIGHT and HOLLOWELL 1958). The results of this experiment add further support to this conclusion, since growth of bean plants at 20°-20°C as day/night temperatures delayed flowering. Moreover, it was observed from the data that flower initiation of bean plants was accelerated by a period of low temperature during night. In this connection, it may be mentioned that AITKEN (1955), found that flower initiation for all varieties of subterranean clover was accelerated by a period of low temperature.
s
-
-
-
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e
Y
r t r
Growth, productivity and compositional contents of bean etc.
575
The results of yield determinations obtained from this work showed clearly that there was no significant change in the number of pods per plant as a result of different night-temperature treatments. From this result we may conclude that night-temperature had no effect on the number of flowers setting pods. On the other hand, weight of pods was significantly decreased in bean plants grown at night-temperatures below or above the optimum temperatures. In this connection it may be mentioned here that many workers reported reductions in the yield of seeds of many plants as a result of exposure to high temperatures (cf. MILTHORPE and HOROWITZ 1943; MEDERSKI and JONES 1963; SEMENIUK and STEWART 1963). The number and weight of seeds per plant were found to be significantly decreased by high night-temperature. It is worthy to note here that plants grown at 5, 10 and 15 DC. night-temperatures produced more or less the same number of seeds. On the other hand, growth at 5 DC., night-temperature resulted in significant decreases in the weight of bean seeds as compared with growth at 10 and 15 DC. night-temperature trements. In this connection, EVANS (1957), working on beans, found that lowering the temperature of growth not only increased the number of mature pods per plant, but also tended to increase the number and size of seeds in each pod. The analysis of bean seeds for their total-nitrogen contents revealed that subjection of bean plants to diurnal fluctuation in temperature during growth, resulted in significant increases in the total-nitrogen contents of the seeds. On the other hand, growth of plants under night-temperatures of 5, 10 and 15 DC. resulted in non-significant differences in the amounts of total-nitrogen of the seeds. The soluble-nitrogen contents of the seeds obtained from plants grown under lower night-temperatures were significantly more than those found in seeds of plants grown under high nighttemperature. The protein-nitrogen contents of the seeds were found to be correlated with the results obtained for total-nitrogen content. On the whole, we may conclude that a fluctuation of day and night-temperahues resulted in significant increases in all nitrogen constituents of the seeds. The decrease in nitrogenous contents of bean seeds observed at high night-temperature may be attributed to either decreased absorption of nitrogen compounds from the soil or to a decrease in the rate of nitrogen assimilation. The analysis of bean seeds for their carbohydrate contents revealed that reducing sugars are nearly absent and the main soluble sugar found was sucrose. It was found that plants grown at lower night-temperatures produced seeds containing more amounts of sucrose than those of plants grown at higher night-temperatures. In this connection it may be mentioned here that ITo and TAKEDA (1963), found that sugar contents of sugar beet were highly increased with low temperatures. Polysaccharides were found to be the main carbohydrate constituent of bean seeds. The analysis of seeds for their polysaccharide contents revealed that daily temperature fluctuation significantly increased this carbohydrate fraction. Maxi-
576
H. SAID, T. HEGAZY and R. M. IMAM
mum increase in the polysaccharide was found in seeds produced by plants grown at 10°C. night-temperature. It is worthy to note here that growth of bean plants at 20-20 DC. as day and night-temperatures produced seeds with the least amount of polysaccharide content .. Literature . AITKEN, Y., 1955. Australian Jour. Agric. Rec. 6 (2), 212-244. - 1955. Ibid. 6 (2), 258-264. ALBAN, E. K.; 1951. Market Growers Journ. 80 (3), 9, 10, 28, 29. cf. Biolog. Abs. 19793. DE RAFOLS, W., 1956. An Inst. Aac. Invest. Agron (Madrid), 2 (1), 3-52, cf. BioI. Abs. 19440 (1954). DMITRENKO, V. P., 1962. Tr. Ukrain. Nauchn. Issled. GidrometeoroL Inst. 28, 13-23, Referat. Zhur., BioI., 1962, No. 23 G. 217. cf. Biolog. Abs. 3196 (1964). EVANS, L. T., 1957. Experimental control of plant growth, P. 124-128. The Ronald press company. HIESEY, W. M., 1953. Amer. Jour. Bot. 40 (4), 205-22l. ITO, K., and TAKEDA, T., 1964. Proc. Crop. Sci. Soc. Japan, 31 (3), 272-276 (1963), cf. Biolog. Abs.30297. IVANOV, S. M., 1935. Bull. AppL Bot., Genet. and Plant-Breed. Ser., 36, Russ. 163-198, cf. Biolog. Abs. 9326 (1937). KNIGHT, W. E., and HOLLOWELL, E. A., 1958. Agrom. Jour. 60 (6), 295-298. KURKI, L., and WITTWER, S. H., 1957. Maataloustieteellinen Aikakauskirja, 28 (4), 223-228. l\hDERSKI, H. J., and JONES, J. B. jr., 1963. Soil Sci. Soc. Amer. Proc. 27 (2), 186-189 cf. Biolog. Abs. 6940 (1955). l\iILTHORP, F. L., and HOROWITZ, B., 1943. Agric. Gaz. N.S. Wales, 64, 53-57. ROBBIN'S, W. R., Sand and water culture methods used in the study of nutrition, P. 86. Commonwealth Agricultural Bureaux England. SAID, H., 1941. Bull. Fac. Sci. Fonad I Univ., Cairo 24, 13. - 1945. Ibid. £0, 117. - and EL-SHISHINY, E. D. H., 1944. Plant PhysioL 19 (4), 660-670. SEMENIUK, P., and STEWART, R. N., 1963. Prac. Amer. Soc. Hart. Sci., 82, 583-686 cf. Biolog. Abs. 7926 (1964). THOMPSON, H. C., 1929. Proc. Internat. Congress Plant Sci. Ithaca, N. Y. 1926, 2, 1070. TUKEY, L. D., 1962. Bot. Gaz. 114 (2), 165-166. ULRICH, A. J., 1956. Jour. Amer. Soc. Sugar Beet TecbnoL 9 (2),97-108, cf. Biolog. Abs. 12335 (1960). VIGLIERCHIO, D. R., and WENT, F. W., 1957. Amer. Journ. Bot. 44, (5), 449-453. WENT, F. W., 1944. Amer. Journ. Bot. 31 (10), 597-618. - 1945. Ibid. 32 (8), 469-479. _ and ENGELSBERG, R., 1946. Arch. Biochem. 9, 187-200, cf. Ann. Rev. Plant. PhysioL 4, 347-362 (1963). WITTWER, S. R., and TEUBNER, F. G., 1957. Amer. Journ. Bot. 44 (2), 126-129. Author's address: Dr. H. SAID, Prof. of Plant Physiology, Cairo University; Dr. T. HEGAZY, Prof. of Plant Physiology, N.R.C.; R. M. IMAM, Research Assistant, Plant Metabolism Unit, N.R.C., National Research Centre, Sh. el-Tahrir, Cairo-Dokki (Egypt).