Improving Growth, Yield and Resistance to Viral Diseases of Potato Plants Through Modifying Some Metabolites Using Zinc Sulphate and Jasmonic Acid
Two field experiments were conducted during the seasons of 2014 and 2015 to study the effect of foliar application of ZnSO4 at 0, 25 and 50 ppm and JA at 0, 10 and 20 μM individually and in combination on potato plants grown under drip irrigation system. The results indicated that the growth parameters in term of shoot fresh and dry weights were increased significantly (P≤ 0.05) in ZnSO4 applied plants; whereas, JA inhibited both traits compared to the untreated plants in both seasons. A similar trend was observed in respect to the concentration of photosynthetic pigments (chlorophyll and carotenoids). On the other hand, total soluble proteins and phenolic compounds were responded positively and significantly to both examined compounds. There were significant increments in the weight of tubers.plant-1 and the total yield of tuber (ton. fed 1-1) by both investigated compounds. In general, the combination treatment of ZnSO4 at 50 ppm + JA at 10 μM gave the highest results in this respect. Symptoms developed on expected plants to be viruses (PVY, PVX and PLRV) infected revealed that the treatment of ZnSO4 at 50 ppm + JA at 10 or 20 μM decreased the percentage of disease incidence in comparison to the other treatments. These results were proved serologically by DAS-ELISA test. The concentrations of PVY and PLRV were decreased significantly in ZnSO4 and/or JA treated plants compared to the controls in both seasons; whereas, PVX was not found in all treatments. The correlation coefficient between all studied biochemical constituents and the concentration of viruses in term of the values of DAS-ELISA test revealed that there was inverse and strong significant correlation between the concentration of total soluble proteins or phenolic compounds on one side and the concentration of PVY or PLRV on the other one. No significant relationships were detected for photosynthetic pigments in this respect.