Responses of Some Photosyntetic Parameters in C3 and C4 Crop Plants Under Water Deficit
Some authors(1) concluded that photosynthesis at low Ψw was more limited by the loss of chloroplast activity than by increased difussive resistance. RBPC activity decreased in bean and cotton plants at water stress(2)(3)(4). PEPC and RBPC activities decreased at water stress in barley plants(5). In mesophyll cells from bean and tomato plants there was decreased in CO2 fixation at fairly low osmotic potentials which simultaneous with stomatal closure(6). Recently it was reported(7) that in soybean leaves a non stomatal limitations of leaf photosynthesis under drought stress conditions appears to be due in part to a reduction in the in vivo activity of RBPC. On the other hand it has been reported that chlorophyll content (8) (9) (10) shows alterations due to water stress. In the present work we pretend to compare the responses of carboxylase activities and chlorophyl content to water deficit in two maize hybrids (C4)(CPB2 and CPB8), two tomato cultivars (C3)(Pera Quibor, PQ and Río Grande, RG) and two bean cultivars (C3)(Tacarigua,T and VUL-73-401,V).
KeywordsWater Stress Water Deficit Chlorophyll Content Tomato Plant Relative Water Content
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