Morphophysiology of Jatropha curcas L. plants under different water regimes

Abstract

The effect of different water regimes on Jatropha curcas seedling growth was investigated. The study was carried out in a greenhouse covered with transparent plastic. Seeds were sown in five-liter recipients containing substrate consisting of 3:1:0.5 soil, sand and manure, respectively. A completely randomized plot design was used with seven treatments and five replications. The plants were irrigated with 100% substrate retention capacity until 30 days of age when they were submitted to water volumes of 25%, 50%, 75%, 100%, 125%, 150% and 175% substrate retention capacity for 30 days. The short duration of the research explains the slight decreases in the RMR and TRA but they were sufficient to support the assertion that excess water may have inhibited aquaporin activity and partially reduced soil solution absorption and TRA. Thus, both water deficit and excess water inhibited the growth of J. curcas plants, however, the water deficit inhibited more strongly the development of the species at the initial stages of the restriction, while excess water only caused damage after a longer period of exposure. The assessments were made when the plants were 60 days old. The J. curcas plants showed an isohydric mechanism of stomatal control and maintained turgidity under water shortage, and, under excess water, the alterations in the root system and relative water content preceded reduction in stomatal conductance. The initial growth of J. curcas plants was shown to be sensitive to water shortage and but not very vulnerable to water excess.