[Regulation of different calcium forms on the photosynthesis of tomato leaves under heat stress].

ABSTRACT

The regulation of different calcium forms, namely CaCl2, Nano-calcium and Manntiol-calcuim, on the gas exchange and fluorescence of tomato leaves under heat stress was investigated. The results showed that all forms of calcium alleviated the decrease of chlorophyll a and carotenoid contents in leaves of tomato seedlings under heat stress, enhanced the net photosynthesis rate (Pn), transpiration rate (Tr) and stomatal conductance (g(s)) to varying degrees, reduced the quantum yield of non-regulated energy dissipation [Y(NO)] of PSII and quantum yield of non-photochemical energy dissipation in PSI due to acceptor side limitation [Y(NA)], promoted the regulated energy dissipation [Y(NPQ)] and quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation [Y(ND)], and increased the calcium content in leaves. Generally, manntiol-calcium and nano-calcium were more effective than CaCl2, and more suitable to enhance the photosynthesis of leaves oftomato seedlings under heat stress.