Water Use Efficiency and Yield of Maize Hybrids Under Deficit Irrigation Using GT Biplot Analysis in the Gorgan Region of Iran

Abstract

Deficit irrigation is one of the most important factors limiting plant growth and production, so the best way to deal with water deficit stress is to identify and develop stress-resistant cultivars. This experiment aimed to assess the impact of deficit irrigation on the yield of both forage maize hybrids. The study was structured as a split-plot design, utilizing a randomized complete block design with three replications, at the Agricultural Research Station of Gorgan during 2021 and 2022. Deficit irrigation was implemented at four different levels as the main plots (100%, 75%, 50%, and 25%) of the water requirement. These main plots were further subdivided into subplots, consisting of four hybrid varieties, namely SC703, SC704, ZP548, and BK50. The results showed that the all traits day to silking, days to maturity, thousand-grain weight, grain yield, number of seeds per cob, water use efficiency were influenced of the interaction effect of deficit irrigation × hybrid was significant at a 1% level. Also, the highest grain yield (8977 kg h⁻¹) from the treatment of 100% water requirement × ZP548 hybrid was obtained. The reduction in yield of the 75%, 50%, and 25%, when compared to the control treatment, amounted to 7.52% (8301 kg h⁻¹), 51.52% (4352 kg h⁻¹), and 82.38% (1581 kg h⁻¹), respectively. The highest water use efficiency was observed in the treatment of 75% water requirement × ZP548 hybrid (1.16 kg m⁻³). The GT biplot for genotype data explained 96.6% of the total variation of the standardized data. Considering the significant reduction in water consumption (2299 m³ h⁻¹) achieved with this treatment, it is advisable to recommend irrigation at 75% of the water requirement alongside the cultivation of the ZP548 hybrid in the north of Iran.