Effect of irrigation water pH on the agronomic development of hops in protected cultivation

Abstract The hydrogenionic potential (pH) is one of the parameters that characterize the quality of water for irrigation, and can influence soil microbiology and the cation exchange process between soil and plant. However, there are few studies related to the pH of irrigation water for hop culture. According to this, our work aimed to evaluate the irrigation effect with different water pH ranges on the agronomic development of hops grown in a greenhouse, in Botucatu, state of Sao Paulo, Brazil. It was used a completely randomized design (CRD), with three treatments (pH levels) and ten replications. The treatments consisted of three water pH levels: T1 – 6 to 6.5, T2 – 6.5 to 7, and T3 – 7 to 7.5. To obtain the different pH ranges were used solutions of 0,1 mol L−1 of sodium hydroxide (NaOH), and phosphoric acid (H3PO4). Gas exchanges, nutritional content in plant leaf tissue, yield, and alpha and beta-acids concentration were evaluated. The results obtained allowed us to conclude that the pH range 6.5 to 7 promotes greater availability, absorption, and accumulation of K in plant leaf tissue, as well as greater photosynthetic capacity, in addition to greater yield between treatments. The preliminary values of alpha and beta-acids were higher in plants irrigated with the water pH of T1, indicating that possible stress may favor the production of these compounds.