Effect of Supplemental Irrigation on Durum Wheat (Triticum durum) Crop and Water use Efficiency under a Saline Environment in the Lower Cheliff Plain

In Algeria, the launching of projects encouraging the practice of supplemental irrigation on cereals to increase productivity and the sustainability of farms in arid and semi-arid regions is confronted with the problems of water use efficiency and soil quality conservation. The use of poor-quality irrigation water for supplemental irrigation is subject to secondary salinization processes, which become worse over time. The present paper aims to study the impact of supplemental irrigation on the increase of durum wheat yield, water use and soil salinization, a trial was set up in the soil of the HMADNA experimental station (RELIZANE, Lower-Cheliff). The experimental set-up is a randomized block with three replications and five treatments (water regime): T1 rainfed, T2 irrigated at tellering stage (T), T3 irrigated up to booting stage (TB), T4 irrigated up to heading stage (TBH) and T5 irrigated up to grain filling stage (TBHF). The parameters studied were: grain yield (GrYd), water consumption or actual evapotranspiration (AET), water use efficiency (WUE), soil salinity (EC) and water satisfaction rate (Ts). The analysis of the variance of the measured parameters showed significant to highly significant differences. Under the experimental conditions of the study site, the supplemental irrigation corresponding to the T5 water regime with an AET of 543mm, contributed significantly to the increase in grain yield up to 62.64 Qx/ha with a WUE of 11.83 Kg/ha/mm and a Ts of 96.31%. Moreover, an irrigation water quantity of near 113mm at the end of the wheat vegetative cycle (grain filling stage) causes the leaching of salts from the surface layer (H0-20cm) previously acquired during the vegetative cycle of the crop. The behavioural study of the saline profile showed that the salinity of the H20-40cm layers undergoes a secondary salinization process with an increased rate ranging from 100% to 220%. In saline environments, the contribution of supplemental irrigation is very important to ensure sustainable food security within specific phenological stages (end of cycle) according to the prevailing climatic conditions of the area while meeting the water needs of the crop.