Abstract:

In order to support application of rare earth element La in watermelon production, grafted watermelon “Heifeicui” and “Jinshuai” on the foliage at straw period, incipient blooming period and fruit expansion period were sprayed with 0, 60,120,180 and 240 mg/L of La(NO3)3 solution, The activities of SOD,POD ,cell membrane permeability, photosynthesis rate and the content of chlorophyll, MDA in watermelon leaf were test. Results showed that the optimum concentration of La3+ could promote the growth of grafted watermelon. Compared to the control, the SOD activity ，the content of chlorophyll and photosynthesis rate in “Jinshuai” leaf were increased 12.65% ,33.00% and 4.10%; the activities of POD and MDA content decreased by 56.97% and 44.09%; the cell membrane permeability decreased by 35.41%. The physiological indicators in leaves of grafted watermelon “Heifeicui” showed the same tendency. The above analysis shows that the most suitable concentration of La(NO3)3 is 120 mg/L.