Effet de l'irrigation déficitaire contrôlée sur la croissance et le développement foliaire du palmier dattier (Phoenix dactylifera L.)

Water is a limiting factor for the development of oasis agriculture. Water use efficiency needs to be improved by searching for different strategies of deficit irrigation. In this context, the response of date palm to these strategies was evaluated by the experimental study of the effects on the vegetative growth of mature palms cv Majhoul. The experiment was conducted in Tafilalet (Morocco) for two consecutive years (March 2012-February 2014). The annual cycle of growth and development of this variety was divided into three distinct periods: the first from November to February, the second from March to June, and the last from July to October. During these times, seven water regimes were applied under drip irrigation: farmer regime (T0), 100% (T1), 80% (T2), 60% (T3), 80-100-60% (T4), 150% (T5), and 60-100-80% (T6) ETM. The measures focused on the monitoring of meteorological parameters, the water irrigation and the evolution of vegetative biomass (emission growth and senescence leaves, and monitoring LAI [Leaf Area Index]) of this variety. The results at the end of the second year of this trial show that: water regime and periodization significantly affected the phenology of the date palm in the second year; water irrigation needs are, on average, 51 m(3)/tree/year, varying between 30 and 76 m(3)/tree/year; the average production of palm and leaf area index were 17.8, 21.1, 20.3, 19.4, 20.1, 20.5, and 21.4 palm/year/tree and 1.01, 1.26, 1.26, 1.22, 1.26, 1.25 and 1.37, respectively for treatments T0, T1, T2, T3, T4, T5, and T6. Thus, the T6 water regime (regulated deficit irrigation) improved the vegetative growth of date palm and allowed the conservation of 14% of irrigation water compared to T1. The strategy of regulated deficit irrigation could contribute to the rationalization of water and the sustainability of oases.