Assessment of ET-HS model for estimating crop water demand and its effects on yield and yield components of barley and wheat in semi-arid region of Iran

Abstract

In order to estimate the water requirement of barley and wheat by using of ET-HS model, a research was conducted at Research Farm of Islamic Azad University, Isfahan (Khorasgan) Branch, Iran. ET-HS model is used to determine irrigation water quantity and irrigation schedule for different crop. The study was based on randomized complete block design (RCBD) with three replications and six treatments. The irrigation treatments included irrigation to supply 50, 75, 100, 125 and 150% of crop water demand on the basis of ET-HS model during growing season and control treatment (conventional irrigation), which was irrigation on the basis of 70 mm evaporation from Class A evaporation pan during growing season. In barley experiment, the highest values for number of fertile tiller, maximum LAI, total dry matter in maximum LAI stage, number of grain per spike, a thousand seed weight (35.56 g), grain yield (7877.9 kg/ha), biological yield (17689.7 kg/ha) and harvest index (44.45%) was obtained for irrigation according to 100% of crop water demand on the basis of ET-HS model. In wheat experiment, the highest number of fertile spike, number of grain per spike, 1000 grain weight, grain yield, biological yield was obtained for irrigation treatment on the basis of 100% ET-HS model; moreover, the maximum harvest index was related to control treatment, followed by irrigation on the basis of 100% of ET-HS model. Conclusively, the appropriate irrigation treatment was 100% of crop water demand on the basis of ET-HS model during the growth season for both crops.