Effect of Irrigation Levels and Some Soil Applied Herbicides on Weeds, Water Use efficiency and Productivity of garlic (Allium sativum L.)

Two field experiments were conducted during 2016/2017 and 2017/2018 winter seasons in clay soil at El-Kanater El-Khiria, Horticulture research station to study the effect of two irrigation water regimes i.e. 75 & 100 % of potential evapotranspiration (ETc) under six weed control treatments by Pendimethalin (Stomp extra 45.5% CS at the rate of 1.7 l/fedden), oxyfluorfen (Roal 24% EC at the rate of 750 cm³/fed. and/ or supplemented with additional hand hoeing once and hand hoeing twice addition to unweeded check on weeds , garlic yield and their water relationship i.e. consumptive use (Cu) and water use efficiency (WUE).Experimental design was split plot where the two treatments of water regime were allocated in the main plots and weed control treatments in subplots in four replicates. The main findings show that the experimental field was infested by annual weeds for the unweeded check by 1.35 and 1.47 ton/feddan dry weight of weeds, exhibited yield loss of 16.1 and 15.1% of garlic yield per feddan than hand hoeing twice in both 2016 /2017 and 2017/2018 seasons, respectively.Also all various weed categories as well as various yield components and yield of garlic tended to increase significantly in both seasons with adding irrigation water by 100 % from potential evapotranspition (ETc) treatment, meanwhile, water use efficiency for irrigation treatments tended to increase by 75 % from potential evapotranspition (ETc) 19.9 and 25.2% of ETc in 2016 /2017 and 2017/2018 seasons, respectively, and economically feasible. The reduction in garlic yield under irrigation level by 75 % equal 7&4 % in 1^st and 2^nd seasons and can consider non mean full difference with saving irrigation water476 &579 cubic meter which equal two irrigation. While, water use efficiency for Stomp at 1.7 L/fed, Stomp + h. hoeing once, Roal at 075 L/fed, Roal+ h. hoeing once and h. hoeing twice tended to increase by 34.0 & 53.8 & 28.8 & 43.4 and 29.7%, respectively more than unweeded check in the first season and by 29.2 & 38.4 & 27.0 & 31.9 and 26.5%, respectively, more than unweeded check which attributed the reduction of weed competition for water consumption. All weed control treatments gave significant effect on controlling weeds and increased growth characteristics and bulb garlic yields. Stomp at 1.7 L/fed h plus hand hoeing once gave the highest increase in net income (LE) by 118.3 and 94.4% respectively, more than unweeded check. Regarding, the interaction between irrigation water levels and weed control treatments, there was a little significant effect with soil moisture 100 % and herbicide residue of Stomp and Roal herbicides which in weed control elements used in garlic bulb less than allowable level.