Effect of Supplemental Irrigation on Wheat Performance Grown in Semi-Arid Environment

Abstract

This study was carried out to determine the effects of different supplemental irrigation (SI) treatments on yield, yield components, and some drought-related traits in eight wheat varieties grown in the semi-arid environment of Jordan. Two SI treatments were used in addition to the control (i.e. rainfed treatment with 262.8mm accumulated rains): partially SI treatment (PSI=262.8mm rains+220mm irrigation at anthesis stage) and continuous SI treatment (CSI= 262.8mm rains + 377.5mm at 2-3 weeks intervals during different stages of wheat growth). Seven durum wheat varieties; namely Sham1, Omqais, Acsad65, Bani Suef6, Bani Suef4, Horani Nawawi, and Dairalla6 in addition to one bread wheat variety (Ammon) were included in this study. Yield and yield components were significantly increased and the time required to anthesis and maturity were delayed by SI. PSI treatment significantly increased grain yield by 50.2%, while CSI increased yield by 121% as compared to the control treatment. Considerable variations among varieties were observed under different irrigation treatments. Sham1 (2266.7 kg ha-1), Omqais (2253.3 kg ha-1), and Acsad65 (1963.3 kg ha-1) gave the highest grain yield under control treatment with low drought susceptibility indices, implying their low grain yield losses under control as compared with SI treatments with high genetic potentials for drought tolerance. The top-yielding varieties under CSI were Acsad65 (4716.7 kg ha-1), Dairalla6 (4586.7 kg ha-1), Bani Suef6 (4460 kg ha-1), and Omqais (4360 kg ha-1). Under PSI, Sham1 (3303 kg ha-1) followed by Dairalla6 (3193.3 kg ha-1), Horani Nawawi (3130 kg ha-1), and Bani Suef6 (3026.7 kg ha-1) gave the highest grain yield. All yield components (number of kernels per spike, number of tillers, and grain size) significantly contributed to increasing grain yield under SI. In conclusion, SI under rainfed conditions improves yield-attributing traits, which led to a substantial increase in grain yield. It would be possible to increase GY by more than 3 and 4 tonnes ha-1 with PSI and CSI, respectively.