Effects of soil drought during the vegetative phase of seedling growth on the uptake of 14co2 and the accumulation and translocation of 14C in cultivars of field bean (vicia faba L. Var. Minor) and field pea (pisum sativum L.) Of different drought tolerance |
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| Authors: | S Grzesiak M Grzesiak T Hura |
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| Institution: | Authors' addresses: Dr S. Grzesiak (corresponding author) and Mgr T. Hura, The Franciszek Górski Department of Plant Physiology, Polish Academy of Sciences, Podluzna 3, PL 30239 Cracow, Poland;Mr M. Grzesiak, Institute of Chemistry, Jagiellonian University, Ingardena 3, 30060 Cracow, Poland |
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| Abstract: | During the vegetative phase of growth of two field bean and two field pea cultivars of different drought tolerance, the effect of short and prolonged soil drought on gas exchange (CO2 i H2O), leaf water potential (ψ), stomatal diffusive resistance (rS), uptake of CO2, and the distribution and accumulation of 14C was studied. Differences in the response to drought conditions between resistant and susceptible cultivars were marked. After 5 days of soil drought, the decrease in net photosynthesis and transpiration rate and the increase of stomatal resistance were greater in the drought-resistant cultivars than in the drought-susceptible ones. In contrast, after 10 days of drought the decrease of leaf PN (CO2 assimilation rate), E (rate of transpiration) and ψ (water potential) was greater in the susceptible cultivars than in the resistant ones. Significant differences between the resistant and the susceptible cultivars were also observed in the assimilation and translocation of 14C by the green parts of the plant. The amount of carbon accumulation in roots in drought-susceptible cultivars increased less than in the drought-resistant cultivars. For treatments in which optimal soil watering was resumed after 5 or 10 days of drought there was no evidence of effects of drought on the majority of measurements, but the drought-resistant cultivars showed a general tendency for a more rapid recovery. Our results confirm the existence of genetic variability in drought tolerance among the cultivars of field bean and field pea. The recorded differences in the response to drought of experimental cultivars may indicate that, under water deficit in the soil and in plant tissues, they may use different strategies to avoid the damaging effects of temporary limitation of water supply; for example, the drought-resistant cultivars may more effectively conserve tissue hydration through effective stomatal closure. Also, the observed changes in carbon assimilation and accumulation might be the reason for their different responses to drought. The change in radioactivity losses in the control and stressed plants may result from the differences in demand for energy to maintain cell structure and function. Similarly, the less intense carbon accumulation in the roots of the sensitive cultivars could be caused by more harmful effects of drought on root growth. |
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| Keywords: | 14CO2 uptake —14C dissimilation and accumulation — drought — field bean — field pea — gas exchange — water potential |
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