Influence of Soil Drought on Plant Growth, Assimilation and Dissimilation of CO2and Accumulation of Photosynthates in Field Bean (Vicia fabaL. minor) During Pod Formation and Rapid Pod Growth

摘要

AbstractField bean planes cultivar Nadwiślański were submitted to soil drought (30 of field soil water capacity) for 5 days at the stage of pod formation (A) and of rapid pod growth (B) and then exposed for 20 minutes to14CO2. Radioactivity of leaves, stems, roots, and pods or pod shells and seeds was measured 1, 5, 24 and 48 hours after exposition.In both stages soil drought reduced by about five times total CO2assimilation, mainly owing to lower activity of the photosynthetic apparatus and also, though less so, to reduced leaf growth. Photosynthetic activity referred to the dry weight of the leaves dropped to 22‐35 of controls. Accumulation of photosynthetates in generative organs was much less depressed than14CO2assimilation. 48 hours after exposition to14CO2of drought treated plants, the contents of14C of pods in phase A, and seeds in phase B, amounted to respectively 24 and 36 of assimilated14C and equalled 91.5 and 74 of the corresponding values for controls.The progressive decline of radioactivity in leaves and stems after14CO2exposition was distinctly correlated to the rise of radioactivity of generative organs both in soil drought treated plants and in controls. Slightly lower values of correlation coefficients in drought treated plants may indicate impairment under drought conditions of synchronization in processes of unloading and accumulation of assimilates.In plants drought treated in phase A the ability to dissimilate14C was reduced to about 59 of that in controls, but when drought was applied in phase B, dissimilation rate was about three times as h