CHANGES IN BIOMASS, CHLOROPHYLL CONTENT AND GAS-EXCHANGE OF BEANS ANDPEPPERS UNDER NITROGEN AND WATER-STRESS

We experimentally produced moderate water stress that reduced leaf, st em, root and fruit biomass of peppers, and severe nitrogen (N) limitat ions that almost stopped their development. Root/shoot ratios (R/S) we re higher in N-limited plants. Low water availability (and also low N availability) produced lower stomatal conductance (g(s)). Specific lea f mass was higher and chlorophyll (Chl) concentration was lower under low N-availability. The same experimental conditions produced smaller differences among treatments in beans (with N-fixing symbionts). Water stress increased its relative importance as shown by the induced incr ease in root/shoot ratio. N stress was less important as shown by the absence of effects on Chl concentrations and g(s). Both peppers and be ans responded to limited availability of nitrogen and water by allocat ing to structures involved in uptake (roots), by longer organ duration , and by increasing the efficiency of N and water use.