Effect of potassium silicate and L-cysteine on yield, water use efficiency and fruit quality of Physalis (Physalis peruviana L.) under water deficit conditions

Nowadays, due to climate change and a decrease in rainfall, the production of agricultural products in many regions, especially arid and semi-arid regions, has faced problems. For this purpose, to study the effect of potassium silicate (Si) and L-cysteine (Cys) foliar spray on water use efficiency, fruit yield and quality of Physalis (Physalis peruviana L.) under water deficit conditions, a split-plot experiment based on a randomized complete block design with three replications was conducted in the Research field of the University of Zanjan during 2022. Experimental treatments consisted of three different irrigation levels (50, 75 and 100% ETc) as the main plot and a foliar spray of potassium silicate (0, 500, 1000 and 1500 mg L-1) and L-cysteine amino (0, 20 and 40 mg L-1) as a subplot. The results showed that water deficit stress increased total soluble solids (TSS), titratable acidity (TA) and protein contents, and decreased vitamin C content, fruit number and yield. Application of Si, especially at 1000 and 1500 mg l-1 and Cys improved carotenoids, TSS, TA, vitamin C and fruit protein contents, and fruit yield under irrigation 100 ETc% and water deficit stress conditions. The highest fruit yield was obtained with the application of 20 and 40 mg L-1 Cys under irrigation of 100 and 75 ETc%. Also, the highest value of WUE was observed in plants treated with 20 and 40 mg L-1 Cys under deficit irrigation of 75 ETc% and 1000 mg L-1 Si under deficit irrigation of 50 ETc%, respectively. Therefore, the application of 1000 mg L-1 of potassium silicate and 40 mg L-1 of cysteine is suggested to increase the quality and yield of the physalis under the irrigation 100 Etc% and water deficit stress conditions.