Plant growth, metabolism and adaptation of glycine max and phaseolus vulgaris subjected to anaerobic conditions and drought

ABSTRACT

The present study was to investigate further the effects of water stress whether induced by water regime or excessive water supply on growth, yield and metabolism of three, leguminous plants [Phaseolus vulgaris cv. Giza 3, Phaseolus vulgaris cv. Contender and Glycine max cv. Crowford] to observe differences, in growth and metabolism, if any among these three plants of commercial interest in Egypt. The induction of water stress was applied in the form of four different water treatments; two of them were drought treatments [water withholding] where the two other treatments were anaerobic water stress [excessive water supply]. Except for the stimulation effect which was elected in growth criteria of soybean plants [shoot length, number of leaves, fresh and dry weights and mean leaf area of the fully expanded leaves] at the flowering stage in response to the excessive water supply, water withholding [at two levels] and excessive water supply [at the higher level] treatments reduced these growth criteria of the three tested plants during the experimental stage. On the other hand, the low level of excessive water supply [wet treatment] stimulates the growth criteria of the tested plants. Treatment of the three bean plants with various water levels led to marked changes in the total amounts and in the relative composition of carbohydrate and nitrogen contents in shoots and in the yielded seeds. Furthermore, a highly significant decrease in oil content of soybean seeds under the dry treatment was obtained whereas a reversible situation was apparent in seeds of wet treated plants. In seeds of both P. vulgaris plants, a significant decrease in oil content was induced under wet treatment in relation to control values; both plants did not survive to the yield stage under dry treatment Marked changes were also obtained for the constituent saturated and unsaturated fatty acids in the yield of seeds. In soybean seeds, the dry treatment increased the saturated fatty acids and decreased the unsaturated fatty acids, whereas an opposite results were observed in seeds of wet-treated plants. Also in seeds of both cultivars of P. vulgaris, the increase in saturated fatty acids was accompanied by a decrease in unsaturated ones under wet treatment. In relation to control levels, water stress appeared to induce marked qualitative and quantitative changes in the types of protein produced by the legume plants. These changes appeared to substantiate the conclusion arrived at from the other results that soybean plants can be considered as being more tolerant to water stress than both cultivars of P. vulgaris used