Abstract
Water scarcity and weed infestation are major challenges to soybean production. Therefore, two field experiments were conducted in a strip plot design including three replicates in the 2019 and 2020 summer seasons at Sakha Agricultural Research Station, Agricultural Research Centre, Egypt, to investigate the effect of three irrigation levels (JO (100%), 11 (90%), and 12 (80%)), and six weed control treatments of pendimethalin (T-1), oxyfluorfen (T-2), bentazon + clethodim (T-3), imazethapyr (T-4), hand-hoeing twice (T-5), and untreated check (T-6) on annual weeds, physiological traits, water relations, and yield and its components of soybean cv Giza 111. Results indicated that intermediate irrigation levels lead to the highest yield and economic return, while the herbicide program that resulted in the greatest weed control gave the highest yield. The rate of weed infestation in field experiments was 19.7 and 21.8 t ha(-1) dry weights, which decreased soybean yield by 56.9 and 57.1%, compared to treatment (T-4). The interactions between 100 irrigation level (I0) and imazethapyr (T-4), bentazon + clethodim (T-3), and hand-hoeing twice (T-5) gave the highest significant values of the most studied characters. Furthermore, under 90% irrigation, all weed control treatments give the best control of weeds and the highest values of the economic criteria.