Fruit thinning techniques incorporated with calcium boron or potassium phosphite for improving Medjool date palm fruit quality under semi-arid regions

Abstract Low fruit quality presents a significant challenge for numerous date-producing countries, including certain cultivars resulting from tissue culture. Fruit thinning alone enhances fruit quality but slightly decreases productivity. So, the aim of this experiment was to improve the quality characteristics of Medjool fruits through four different fruit thinning methods: control (12 bunches per palm), removing 1/3 bunches number, removing 1/3 strands length of the bunch, removing 1/3 strands number of the bunches, these methods were integrated with spraying 0.25% calcium boron (CaB) or 0.2% potassium phosphite (KP), as well as control (tap water), which applied once (fruit set or Kimri stage or Khalal stage) for thinning methods. At Kimri stage, removing 1/3 strands number successfully enhanced fruit weight, length, and size by 10.44%, 8.28%, and 15.68%, while incorporating CaB to removing 1/3 strands number led to increases of 43%, 26.78%, and 52.78%, while incorporating KP with removing 1/3 strands number resulted in increases of 42.67%, 26.31%, and 44.22%, compared to control, as mean of both seasons, respectively. At Khalal stage, combining removing 1/3 strands number and CaB increased fruit TSS and total sugars by 18.85% and 33.65%, while combined removing 1/3 strands number and KP increased them by 19.29% and 23.81%, respectively. In conclusion, nutrient spraying improved fruit chemical properties and the early spraying stage was more effective in improving fruit physical properties, whereas later spraying improved fruit chemical properties. Also, thinning enhances fruit physical properties and provides more nutrients for the remaining fruits. The integrated application of thinning and spraying nutrients improved fruit’s physical and chemical properties.