Irrigation scheduling for green beans grown in clay loam soil under a drip irrigation system

Abstract

An experimental field trial was conducted at El-Ayat, El-Giza Governorate, Egypt (latitude 30°11´13"N, longitude 31°41´38"E, and mean altitude 74 m above sea level) during the growing season of 2017 and 2018. The study aimed to assess the suitable irrigation interval and applied water volume for drip-irrigated green beans, based on water production functions and water use–yield relationships. The field trial was arranged in a split-plot design with 3 irrigation intervals (F₁, F₂ and F₃ irrigation events, once every 1, 2 and 3 days, respectively) and 3 irrigation regimes (I₁: 1.00, I₂: 0.80, and I₃: 0.60 of the crop evapotranspiration, ET_c). The results showed that the yield and water use efficiency (WUE) increased with increasing irrigation interval. Maximum and minimum yield of 12 030 and 4 879 kg∙ha^-1 were obtained in F₁I₂ and F₃I₃ treatment, respectively, in the winter season of 2017, and were 12 364 and 4 678 kg∙ha^-1 for the corresponding treatments in the winter season of 2018. WUE ranged from 56.55 kg∙ha^-1∙mm^-1 in F₁I₂ to 23.80 kg∙ha^-1∙mm^-1 in F₃I₃. Plant growth parameters were significantly affected by the irrigation schedule. The highest plant growth parameters were obtained under F₁ and F₂. The seasonal yield response factors (k_y) were 0.845 and 0.856 in 2017 and 2018, respectively. The relationship between yield and seasonal crop ET was best explained by a power function for all irrigation schedules for both growing seasons. It is recommended that the F₁I₂ irrigation treatment is the suitable one for green beans grown under field conditions, in order to achieve the highest yield and WUE.