Changes in yield and chloroplast Mg2+-ATPase activity of wheat (Triticum aestivum L.) in response to soil salinity and nutrient supply [electronic resource]

Includes references.

Under stress conditions such as salinity and drought, plant tolerance depends on upregulating ATPase activity. A greenhouse and a field experiments were conducted to investigate the regulation of chloroplast Mg+2-ATPase activity in wheat in response to soil salinity and nutrient supply. In the greenhouse, plants were imposed irrigation with three water salinities; 0.4, 4.0, and 8.0 dSm-1 with different sub-treatments of nutrient applications. Wheat yield was negatively correlated with soil salinity, presenting threshold at 6 dsm-1 followed by yield reduction with slope 7.4 % per unit dsm-1. Salt stress decreased Mg+2-ATP activity from 0.32 to 0.28 µmole Pi min-1 mg-1chl. Application of mixed fertilizers M.F. (compost, Gypsum, P, and K) for the non stressed plants resulted in increasing both Mg2+-ATPase from 0.32 to 0.40 and the relative grain yield to 120%, suggesting anabolic metabolism. At soil salinity above the threshold level, application of nutrients sharply increased Mg2+-ATPase activity up to 1.06 µmole Pi min-1 mg-1chl accompanying yield reduction; suggesting catabolic metabolism.
In the field experiment, the soil salinity was 12.3 dSm-1 at planting and only drainage water (EC 3.9 dSm-1) was available for irrigation. The soil EC steeply reduced to 5.0 dSm-1 before the productive growth stages. Mg+2-ATPase activity was up-regulated at flowering and was low late in the season at the grain filling stage. Foliar spray with K+ and a biostimulant enhanced ATPase activity as well as grain yield compared to the control. Under the field condition Mg2+-ATPase activity was correlated with the grain yield, which reached 8.7 Mg ha-1. The variation in wheat response in the greenhouse to that in the field may be attributed to the greenhouse conditions that impaired photosynthesis activity and induced catabolic ATP hydrolysis.

Summary in Arabic.