Effects of alternated different irrigation amount modes on growth regulation and water use of Jatropha curcas L.

A pot-grown Jatropha curcas L. experiment was conducted to investigate the effects of alternated different irrigation amount modes on growth regulation and water use efficiency. Four watering treatment mode were designed in pot experiment, i.e. T1(every time irrigation amount for 10mm), T2 (every time every time irrigation amount for 20mm), T3 (every time every time irrigation amount for 30mm), T4 (repeated alternate two kinds of combined irrigation amount as 10mm or 30mm). Result show that: 1) Jatropha curcas L. can live in the environment where irrigation amount was 10 mm and irrigation cycle was 7 d, it was thus clear that it showed great resistance ability to drought stress under T1 treatment, the reason for continue to live and adapt to drought environment was not only by stopping growth and fall off more leaves, but the main reason was that the xylem have similar spongy material can storage more ivory liquid; 2) compared to T3 treatment, T4 treatment saved irrigation water by 21.6%， mean significantly increased the cortex thickness by 24%. Meanwhile, T4 significantly increased WSCleaf, WSCpetiole, WSCmaster rod, WSCcanopy and WSCwhole plant by 28.3%, 28.8%, 13.7%, 17% and 12.3%, respectively. However，T4 treatment significantly reduced the evapo-transpiration quantity and transpiration by 36.8% and 20.4%, respectively, but increased mean the root mass and total dry mass by 21.3% and 1.3%, respectively, thus significantly increased total water use efficiency by 30.2%. Therefore, T4 treatment realized the optimal allocation of water supply by constantly alternate watering quota for 10mm and 30mm, could increase water use efficiency and water storage capability of Jatropha curcas L. by increased root and total dry mass, and significantly reduced transpiration and evapo-transpiration.