Fruit set in Majhoul date palm and fruit drop by chemical thinning

Date palm is very cultivated in Draa-Tafilalet area (the southeastern part of Morocco). The variety diversity is rich and include commercial varieties such as ‘Majhoul’ and ‘Bouffegous’. Fruit thinning consists of reducing the fruit load of date palm in order to obtain a balance between yield and fruit quality and to avoid alternating production. Naphthalene acetic acid (NAA) spray is used on date palm to induce fruit drop. Chemical thinning with NAA has been the subject of several research studies, which have focused on the effectiveness of the operation, the doses used and the periods of its application. The practice is not yet well mastered in Morocco and its advantages are not well known. Our work aims to study the fruit set and the effect of NAA treatments on fruit drop of ‘Majhoul’ date palm . Trials were carried out on an adult plantation in Tafilalet area and obtained results showed that fruit set in the early flowering phase was higher (more than 57%) than in the seasonal (55%) and late (42%) phases. Fruit drop is low before the application of NAA (2.41 fruits/spikelet for the seasonal flowering), while it is higher after its application (7.53 fruits/spikelet for the same phase). This is due to the best period chosen for the first application of NAA (100 ppm) and which favored fruit drop during the first stage of fruit development. The second application of NAA (200 ppm), even with a double dose than the first application, did not significantly affect fruit drop because the fruits are in an advanced stage of their development.