Effects of fruit load intensity and irrigation level on fruit quality, water productivity and net profits of date palms

An integrated research coupling a field study with an agronomic-economic model (ANSWER-APP) was conducted to investigate the combined effects of irrigation levels and crop loads on fruit quality, water productivity and profitability of mature date palms. The study took place in Israel's hyper-arid Arava Valley, where date palm trees are widely cultivated and rely exclusively on brackish water irrigation. Three fruit load intensities (low, FL1; commercial, FL2; high, FL3) and two irrigation levels (W1 and W2, equal to and higher than the local irrigation regime, respectively) were applied in a 22-year-old date palm orchard in 2018–2019. Irrigation amount, fruit quality and yield were measured. Profitability for each treatment was analyzed with the ANSWER-APP. Higher fruit load resulted in higher yield and water productivity, but on the other hand led to reduced fruit physical properties (size and mass), regardless of the irrigation treatment. The improved fruit physical properties and net profits in W2 compared to W1 treatment in each fruit load group resulted from excess salt leaching in the root zone. Notably, trees under W2FL2 treatment were found to have highest net profits. It is concluded that adequate irrigation amounts contribute to net profits in date palm trees treated with high fruit load intensity under saline irrigation conditions.