The impact of heat and water stress conditions on the growth of the biofuel plant Jatropha curcas

Pot experiments were carried out to evaluate the effects of drought and salinity stresses and mulch amendment on Jatropha in sand dune soil under three conditions: glasshouse, shade house and open area. Plants were irrigated with freshwater and diluted seawater adjusted to two levels of electrical conductivity- 3 and 6 dS m ^-1. The results showed that experimental conditions remarkably affected the evapo-transpiration rate, soil moisture, salts accumulation and plant biomass production. Low temperature (23°C) conditions exhibited highest plant growth and soil moisture and lowest salts deposition. Plants showed no symptoms of heat stress in the glasshouse. The shade house and the open area profoundly reduced plant biomass and water content in the soil. Compared to the control, the mulch amended treatments had sufficient water for plant growth even in the high temperature of the open area. High salt content was found in salinity treated pots but the salinity level did not reduce Jatropha growth. Salt accumulated in the salinity treated pots helped retain more water, reduced the temperature and provided nutrients to the plants, with results which were almost similar to those from the mulch effect. The temperature conditions of the shade house and the open area (max>40°C) caused substantial water loss and induced death of plants. Jatropha is a succulent and drought tolerant plant and a close irrigation interval is not the best option for Jatropha growth. But, organic amendment is needed when there is a big loss of soil water due to heat stress condition.