The effect of foliar spray of nano silicone and salicylic acid on physiological traits and seed yield of spring rapeseed at water limitation conditions

water limitation is often the most important preventive factor in spring rapeseed in semi-arid Mediterranean regions. The use of nutrient nanoparticles and exogenous plant growth regulators by influencing plant physiological processes can play an important role in tolerance to water limitation. The aim of this study was to investigate the changes of some physiological traits and seed yield of spring rapeseed in response to foliar spray of nano silicone and salicylic acid under water limitation conditions.

This experiment was conducted as a factorial split plot based on a randomized complete block design with four replications at the Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardebili, in 2017. Water limitation treatments (control or full irrigation, irrigation withholding at stem elongation, flowering and seed formation stages), and foliar spray of silicon in form of Nano- silicon dioxide (nSiO2) at three levels (0, 60 and 300 mg.L-1) and salicylic acid (SA) at three levels (0, 0.5 and 2.5 mM).

The results showed that the main effects of experiment factors on physiological traits and seed yield are significant. The lowest value of leaf greenness index (SPAD) was observed on Full Irrigation, whereas the highest values were obtained from foliar spray 60 mg.L-1 nSiO2 and 2.5 mM SA under irrigation withholding at flowering stage. At full irrigation and irrigation withholding at seed formation stage treatments, the spraying of 300 mg / l nSiO2 resulted in a significant reduction in the quantum efficiency of photosystem II (Fv/Fm) in compared to the lower level of nSiO2. Foliar Spray 300 mg.L-1 of nSiO2 with SA consumption resulted in the reduction of electrolyte leakage from membrane (EC) compared to control treatment. In full irrigation, the highest value of relative water content (RWC) was obtained, especially with foliar spray 300 mg.L-1 nSiO2. Also in between different levels of SA, The foliar spray 2.5 mM SA caused the highest RWC trait. The highest seed yield was obtained from full irrigation In combination with 300 mg. L-1 nSiO2 and 0.5 mM SA (2847.3 kg.ha-1), and the lowest value was belonged to irrigation withholding at flowering and stem elongation stages without foliar spray of nSiO2 and or SA .

It was concluded that foliar spray nSiO2 and SA alone or combined in both conditions of irrigation and or water limitation showed a positive effect on physiological traits and seed yield, however a higher amount of nSiO2 could have a deterrent effect on the positive effects of SA.