ALA Mitigation of Light Stress Effect on Photosynthesis and Vegetative Growth of Chrysanthemum

Chrysanthemum under light stress was used as research object and using the method of spraying exogenous ALA to research the effect of exogenous ALA on the photosynthesis and vegetative growth of chrysanthemum, in order to research the impacts of the ALA.The results showed that the chlorophyll content, photosynthesis decreased and the vegetative growth of chrysanthemum were restrained significantly under the light stress..But spraying exogenous ALA could significantly mitigate the effect of light stress.Spraying 200 mg·L^-1 ALA on chrysanthemum under 50%（T1） and 25%（T2）light stress increased net photosynthesis rate（Pn） 11.41% and 29.09%,light saturation point（LSP） 7.61% and 5.29% respectively.Exogenous ALA decreased light compensation point（LCP） under 50%（T1）and 25%（T2）light stress.Comparing with no spraying ALA,spraying 100 mg·L^-1 and 200 mg·L^-1 ALA on chrysanthemum under 25%（T2）light stress, chlorophyll a content increased 42.00% and 44.00%,stem diameter increased 20.14% and 27.76% respectively.