Influence of irrigation on yield and primary and secondary metabolites in two chilies species, Capsicum annuum L. and Capsicum chinense Jacq

The effects of water stress on plant growth, yield, primary metabolites (sugars, organic acids, ascorbic acid) and secondary metabolites (total phenolic content, capsaicin and dihydrocapsaicin) accumulation, were evaluated for greenhouse production. A pot experiment was conducted on two species of chilies Capsicum annuum L. var 'Chili-AS Rot' and Capsicum chinense Jacq. var 'Naga Morich'. Plants were irrigated at two different treatments, optimal irrigation or field capacity and deficit irrigation or 50 % field capacity, which can be treated as drought stress. The effects of drought stress on quantity and quality of the yield, (primary and secondary metabolites) were studied. Deficit irrigation affected yield quantity, as both chili species had lower yield at deficit irrigation. Species C. chinense 'Naga Morich' under deficit irrigation abscised the flowers, thus no fruits were harvested at the third picking. Concentrations of sugars were lower at both plant species under deficit irrigation. Concentrations of organic acids in fruits of C. annuum 'Chili-AS Rot', such as citric acid, oxalic acid, fumaric acid, quinic acid were higher at optimal irrigation. Malic acid concentrations were similar at both irrigation treatments. In the fruits of C. chinense Jacq. 'Naga Morich' the concertation of citric acid and ascorbic acid was higher with optimal irrigation. Concentrations of other organic acids were higher at deficit irrigation. C. annuum 'ChiliAS Rot' had higher concentration of ascorbic acid and total phenolic content at optimal irrigation and higher capsaicin and dihydrocapsaicin concentrations in stressed plants. C. chinense 'Naga Morich' had higher concentrations of capsaicin, dihydrocapsaicin and total phenolic content at optimal irrigation regime.