Changes in leaf gas exchange, biochemical properties, growth and yield of chilli grown under soilless culture subjected to deficit fertigation

Deficit fertigation (DF) may control transpiration and improve crop water-use efficiency (WUE) without much yield reduction. This study was conducted to assess and compare the effects of deficit fertigation (DF) with standard local grower's practices on growth, yield, leaf gas exchanges and biochemical changes on chilli plant grown in soilless culture. Five treatments including (1) standard local grower's practice (control, T0), (2) 100% fertigation of crop evapotranspiration (ETc, T1), (3) 100% ETc and 2 days fertigation interval (T2), (4) 75% ETc and 2 days fertigation interval (T3) and (5) 50% ETc and 2 days fertigation interval (T4) based on pan evaporation method were evaluated in this experiment. DF was found to affect the production of biomass allocation into leaf, stem, root and yield of chilli. Increase the degree of DF significantly reduced chilli yield from 1060 g plant-1 to 28 g plant-1. All treatments under DF also decreased photosynthesis rate (Pn), stomatal conductance (gs), maximum quantum of yield PSII (Fv/Fm) and relative chlorophyll content of chilli plants. A higher Pn and gs obtained at all growth stages in control plants. Higher fertigation use efficiency (FUE) was found in 100 % ET with 2 days fertigation intervals. Catalase (CAT) and ascorbate peroxidase (APX) were increased from bloom to fruit set and then gradually decreased until fruit ripening stage at all levels of DF treatments. In contrast, guaiacol peroxidase (GPX) was gradually increased from bloom and fruit set until fruit ripening stage at all levels of DF. Thus, the study indicated that growth, leaf gas exchange and yield of chilli grown in soilless culture were significantly reduced under DF than that of local grower's practice.