Salt response of photosynthetic electron transport system in wheat cultivars with contrasting tolerance

Soil salinity significantly decreases the photosynthetic efficiency and plant growth in wheat (Triticum aestivum L.). However, sensitivity of the photosynthetic electron transport system of wheat in relation with salt stress is unclear. Two wheat cultivars with contrasting salt tolerance were exposed to soil salinity, and the physiological responses and performance of photosynthetic electron system were investigated. The depressed photosynthetic carbon assimilation was mainly caused by stomatal closure and lower photosynthetic electron transport efficiency. Under salt stress, the salt-resistant cv. YN19 had higher efficiency in photosynthetic electron transport, hence maintaining higher photosynthetic rate under salt stress, compared with the salt-sensitive cv. JM22. In addition, the parameters derived from fast chlorophyll a fluorescence induction curve, i.e. the quantum yield for electron transport (phi(Eo)) and the probability that an electron moves futher than QA (psi(Eo)), can be used as indicators for rapid screening of wheat cultivars tolerant to soil salinity.