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With increasing demand for biofuels, jatropha is considered as one of the biofuel crops, which is suitable for growth under adverse conditions including drought and salinity which mainly occur in arid and semi-arid environment. We report here to what extent salt stress affected water loss, canopy water vapor conductance, leaf growth and Na and K concentrations of leaves of 3-year old and young plants. Adult (on peat substrate) and young (in hydroponic system) plants were exposed to seven (0–300 mmol NaCl L−1) and five salt levels (0–200 mmol NaCl L−1), during 20 and 6 days, respectively. In both experiments, plants responded rapidly to salt stress by reducing water loss. The threshold value of responses was between 0 and 5 dS m−1. Leaf area increment of young jatropha had a threshold value of 5 dS m−1 implying that jatropha responds sensitive to external salt application in term of canopy development, conductance and CO2 assimilation rate. The rapid decrease of canopy conductance indicates that jatropha is effectively protecting leaves from massive Na import into leaves over short time periods. Our data indicate that use of wastewater in (semi-)arid areas should be carefully considered if high productivity is the key of plantation management. |
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