Response of seed yield of jojoba (Simmondsia chinensis L.) trees irrigated with saline water to compost, phosphorus and nitrogen application

Abstract

Jojoba is a promising industrial seed oil crop that has potential in Egypt's hyper-arid lands. An experiment on jojoba was carried out at Moghra Oasis, northeast of the Qattara Depression in the Western Desert of Egypt. The experiment was carried out in two consecutive years (2020-2021 and 2021-2022) to investigate the jojoba seed yield response to compost, phosphorus (P), and nitrogen (N) fertilization in a split-split plot design. Irrigation water from the utilized well averaged 7.4 dS m -1 , implying that the trees were under salt stress. Main plots were assigned for three rates of compost as 0, 20 and 40 ton ha -1 . Sub-plots were assigned for four rates of phosphorus (P) fertilizer as 0, 80, 160, and 320 kg P 2 O 5 ha -1 . While sub-sub plots were assigned for four rates of N as 0, 125, 250, and 500 kg N ha -1 . The results showed that jojoba seed yield increased in a linear fashion as the rates of all the tested parameters increased. The most effective treatment was to apply P, N, and compost at rates of 320 kg P 2 O 5 , 500 kg N, and 40 ton ha -1 . In the first and second seasons, these rates resulted in jojoba seed yields of 655 and 814 kg ha -1 , respectively. Higher seed yield in the second season may be due to the residual effects of compost, P and K as well as trees size. This study, therefore, revealed that jojoba trees cultivated in hyper-arid conditions and subjected to salt stress respond significantly to compost and mineral fertilizers when applied in sufficient amounts.