Response of Jojoba (Simmondsia Chinensis) Seed Yield to Compost, Phosphorus, and Potassium Fertilization and Their Interactions under Salt Stress

Abstract

Jojoba is a potential oil crop that is grown for a variety of purposes in several countries, and holds a potential in the newly reclaimed lands in Egypt. 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 in-organic and organic fertilizers 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 potassium (K) fertilizer as 0, 100, 200, and 400 kg K 2 O ha - 1 . The results indicated that jojoba seed yield responded positively with the increasing rates of all the studied factors in a linear fashion. Applying P, K, and compost at rates of 320 kg P 2 O 5 , 400 K 2 O, and 40 ton ha -1 were the most effective treatments. In the first and second seasons, these rates resulted in jojoba seed yields of 637 and 773 kg ha -1 , respectively. Higher seed yield in the second season may be attributed to the residual effects of compost, P, and K, as well as the expansion of the trees. In conclusion, this study revealed that jojoba trees grown in hyper-arid condition and exposed to salt stress respond considerably to organic and mineral fertilizers.