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THE INFLUENCE OF TEMPERATURE ON MORPHOLOGY AND GROWTH RATE OF BEAN SEEDLINGS
Author(s) -
Van Dobben W. H.,
Van Ast A.,
Corré W. J.
Publication year - 1984
Publication title -
acta botanica neerlandica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0044-5983
DOI - 10.1111/j.1438-8677.1984.tb01797.x
Subject(s) - relative growth rate , growth rate , dry matter , dry weight , horticulture , specific leaf area , seedling , light intensity , botany , zoology , biology , chemistry , photosynthesis , mathematics , geometry , physics , optics
SUMMARY Bush bean seedlings were grown at 16 and 25°C and two light intensities. At 25°C the relative growth rate (RGR) was twice that of 16°C and plant development took half the time. This suggests a linear proportionality between relative growth rate and temperature in this range because the minimum temperature for growth and development is about 8°C for bush beans. This relation implies that the relative growth rate has a specific maximum which depends on temperature. Slow extension growth induced by low temperature leads to a high level of carbohydrate reserves under conditions of high light intensity. This explains why at 16°C the dry matter content of seedling leaves rises gradually whereas it remains practically constant at 25°C. This also explains why leaf area per unit leaf dry weight drops at 16°C ( fig. 2 ) so that leaf area ratio (LAR) decreases after reaching a maximum ( fig. 1 ). This, however, does not lead to a drop in relative growth rate which suggests that a compensation through a higher net assimilation rate (NAR) occurs. At 25°C the decline of RGR in low light intensity is relatively strong, probably because of a high respiration level. Light intensity and temperature have little influence on the specific weight of leaves ( fig. 4 ). Furthermore leaf area per unit fresh leaf weight appears to be proportional to the inverse of leaf thickness ( fig. 5 ). These findings suggest that inner leaf structure maintains a certain homogeneity independent of outward conditions. Cotyledons are exhausted by the young seedling at a constant rate which is higher in high temperatures and low light intensities.