The effects of PRD (partial rootzone drying) on soilless grown greenhouse pepper

Experiment has been carried out in 2009 early-spring growing period, in order to investigate PRD (Partial Rootzone Drying) technique on soilless grown greenhouse bell pepper. The four irrigation treatments have been realized. In the experiment: (1) Full-open (F-O), (2) Full-closed (F-C), (3) PRD-open and (4) PRD closed systems. Under full irrigation treatments (F-O and F-C), all roots were wetted in every irrigation with the applied amount of nutrient solution using one line of drip irrigation. The treatments of PRD system received 50% reduced nutrient solution compared to full irrigation treatments. In the open systems (F-O and PRD-O), the excess nutrient solution was discharged as drainage from the greenhouse. In the closed systems (F-C and PRD-C), drainage effluent from the base of the growth containers was collected and recycled in the system. In the experiment the effects of the treatments on plant vegetative growth such as height, leaf weight, total biomass weight, leaf area and total yield were not significantly affected by the treatments. Number of leaf was affected significantly by the treatments. The total yields in the experiment from the highest to the lowest treatments were Full-closed, Full-open, PRD-open and PRD-closed with 7.00, 6.88, 5.73 and 5.68 kg/m2 pepper. The leaf analysis in both year experiments for N, P, K, Ca, Mg and Cl showed that the bell pepper plants were adequately and properly fed throughout the growth period in the different treatments. The fruit physical and chemical properties were not significantly affected by the treatments. Relative water content and leaf temperature were not significantly affected by the treatments; however membrane injury, leaf water potential, osmotic potential and stomatal conductance were significantly affected by the treatments. Substrate analysis showed Na, CI and PO4 accumulations in Full-closed, SO4 and Mg accumulations in PRD-Closed treatments.The general conclusions from the project work: Deficit irrigation with PRD technique can be successfully used in soilless grown bell pepper. The PRD applications in soilless grown greenhouse tomato have good potential for saving water and nutrients as well as its environmental friendly nature with minimized drainage discharge.