Effect of chemical thinning on the fruit parameters of ‘Majhoul’ date palm during fruit development

The aim of this work was to study the effect of NAA (Naphthalene acetic acid) on the chemical thinning of ‘Majhoul’ date palm in order to use this operation as an alternative to manual thinning, which is a costly operation carried out by the farmers. Experiments were carried out on an adult plantation of ‘Majhoul’ cv in Tafilalet area. Thinning treatments used were T0 (control treated with water), T1 (application of 150 and 300 ppm NAA 30 and 60 days after pollination), T2 (application of 250 and 500 ppm NAA 30 and 60 days after pollination) and T3 (manual thinning performed by the farmer). These treatments were used on three flowering phases of this variety. Obtained results showed that for the early flowering phase, T2 NAA treatment increased fruit drop for 77% compared to the control. Thinning treatments T1, T2 and T3 yielded fruit with larger size (fruit mass of 17.26, 18.51 and 20.88 g respectively) than that of the control (13.67 g). The late flowering phase also gave fruit with larger size (fruit mass of 18.73 g and fruit length of 4.44 cm) than that of the other flowering phases (fruit mass of 17 g and fruit length of 4.34 cm for the other flowering phases).