The effect of changes in antioxidant enzymes on yield of chickpea with application of zinc, silicon and zinc immobilized on SBA-15 under different mousture conditions

Water stress as the most important environmental stress in arid and semi-arid regions of the world, reduces the quantitative and qualitative yield of crops through affecting on the physiology and biochemistry of plants. Chickpea as an important protein plant is also exposed to Water stress under dryland condition. Damages caused by environmental stresses can partially be reduced with proper nutritional management. The form of nano-fertilizers can be beneficial due to improving plant uptake and accessiblity to the fertilizer. The present study was conducted to investigate the effect of mesopor zinc and silicon (zinc nanoparticles immobilized on SBA-15) on the defense system of chickpea in Water stress.

The research was carried out in Research Farm of Maragheh University with geographical coordinates 37°23' N; 46°16' E and 1485 meters above sea surface in northwest of Iran, during 2018-2019 growing season as Split-plot experiment conducted based on a randomized complete block desing with three replications. The main factor included Water stress (W1: 90% of field capicity, W2: 60% of field capacity, W3: 30% of field capacity) and sub factors included fertilizer treatments F1: control (no fertilizer application), F2: zinc sulfate, F3: silicon, F4: zinc sulfate+silicon, F5: mezopor zinc- silicon. Parametrs such as Plant height, grain yield, activity of Catalas, Ascorbat peroxidas, Guaiacol peroxidase enzymes, H2O2, Malone dialdehyde, chlorophyll a, chlorophyll b and Carotenoid were evaluated.

According to the results of this study, with increasing Water stress intensity, plant height and chlorophyll b significantly decreased and foliar application of mesopor zinc-silicon height increased chlorophyll b about 50% compared to the control. Also the results showed that the catalase, ascorbate peroxidase, guaiacol peroxidase, hydrogen peroxide, malondialdehyde, chlorophyll a, carotenoid, plant height and grain yield were affected by intraction effect of fertilizer × Water stress. With increasing stress intensity, the amount of hydrogen peroxide increased significantly compared to non stress. On the other hand, in all of the traits, the application of fertilizer treatments, especially mezopor zinc- silicon in Water stress (90%, 60% and 30% of field capicity) have the highest amount.Also mezopor zinc- silicon with increasing antioxidant enzymes catalase, ascorbate peroxidase and guaiacol peroxidase were significantly increased, which reduced malondialdehyde by 50% compared to no foliar application in 30% of field capicity. Also, a significant increase in chlorophyll a and carotenoids was observed with the application of this treatment in all three levels Water stress.

In general, the results of this study showed that foliar application of zinc and silicon, especially at high stress intensities is the best treatment composition due to its effect on reducing the amount of hydrogen peroxide and subsequently reducing the amount of malondialdehyde, as well as a positive effect on the plant defense system and reducing Water stress damage and finally increasing grain yield.