Water relations and growth of the weed,goosegrass (Eleusine indica), under drought stress

The relative sensitivity to water stress at different growth stages of goosegrass (Eleusine indica (L.) Gaertner) was investigated by measuring water status and growth of groups of plants stressed during the vegetative stage, the reproductive stage, and during both stages. Plants were grown from seed in large pots in a controlled-environment chamber at 29/23°C and 14-h photoperiod. In all treatments, decreasing leaf water-potential was correlated with decreasing osmotic and pressure potentials. Plants stressed during the flowering stage maintained greater pressure potentials at any leaf water-potential than plants stressed during vegetative growth or stressed twice. Prestressing the plants did not induce lower leaf osmotic potentials at full turgor. However, dehydration was the main cause of low osmotic potentials measured in the leaves of the plants stressed twice. Stomatal closure occurred over a relatively large range of leaf water-potentials. The sensitivity of stomata to water stress in this species was fairly similar in the two growth stages studied. Leaves of plants stressed during the flowering stage had a smaller decline in total biomass during the stress period, and a higher rate of growth after rewatering, compared to the plants that received a stress during vegetative growth and flowering or were stressed during vegetative growth.