The effect of adding chemical fertilizers and spraying with the growth regulator brassinolide and the interaction between them on the growth characteristics and chemical content of date palm trees cultivated in gypsum soils.

Abstract

Abstract The experiment was conducted in the Fallujah Palm Plant - Department of Horticulture - Ministry of Agriculture on palm trees of the Khostawi variety at the age of 10 years, from (15/2/2020) until (21/10/2020). The experiment included two factors, the first is the use of three fertilizer combinations in addition to the control treatment (F0, F1, F2, and F3). The second factor is the use of the brassinolide growth regulator with three concentrations (0, 0.040, and 0.060) mg.L-1, symbolized as Br0, Br1, and Br2, respectively. At a probability level of 0.05, the results of the study are summarized as follows:Fertilization with the fertilizer mixture F3 (urea 900 g + 450 g DAP + potassium sulfate 600 g) resulted in a significant increase in the average number of leaves, the rate of increase in the length of the fronds, the rate of increase in the length of the pinnaes, the content of the leaves of chlorophyll, the percentage of dry matter of the leaves and the content of the leaves from Carbohydrates, nitrogen, phosphorous, potassium and protein, which amounted to 2.41 leaves, 0.203 cm, 0.71 cm, 54.55 spad units, 35.00%, 11.76%, 1.01%, 0.265%, 1.109%, 6.424%, while the control treatment gave the lowest rate for the aforementioned traits. The spraying with the growth regulator brassinolide, especially the concentration 0.060 mg/L-1, resulted in a significant increase in the rate of the number of leaves, the rate of increase in the length of the fronds, the rate of increase in the length of the pinnae, the content of the leaves of chlorophyll, the percentage of the dry matter of the leaves and the content of the leaves of nitrogen, phosphorous, potassium and protein as they reached 2.58 sheets, 0.248 cm, 0.81 cm, 54.78 spad unit, 33.67%, 0.97%, 0.287%, 1.081%, and 6.047%, while the control treatment gave the lowest rate for the aforementioned traits. The studied characteristics, as the interaction treatment F3Br2 gave the highest rate of increase in the studied traits, while the interaction F3Br1 was superior by giving it the highest content of carbohydrates in the leaves.