Response of Date Palm (Phoenix dactylifera L.) Seedlings to Foliar Application of Silicon under Different Irrigation Regimes

Abstract

In Saudi Arabia (SA), date palm seedlings experience aridity stress, which restrict their growth and potentially influence their future productivity. Previous studies showed a potential for the combination between deficit irrigation technique (DI) and silicon (Si) application to reduce irrigation water (IW) and improve water use efficiency (WUE) in various plants. In this study, growth parameters, chlorophyll content, and nutrient uptake were examined in ‘Nabtet-Ali’ date palm seedlings subjected to Si foliar application as K2SiO3 at 0, 5, and 10 mM under 100%, 80%, 0 and 60% of required IW. Seedlings under 100% IW exhibited the highest growth parameters followed by 80% IW and then 60% IW treatment that exhibited the lowest values. Si spray increased Si content in leaves and roots but with no effect on growth parameters. Chlorophyll b increased in plants under 80% and 60% IW; however, total chlorophylls were unaffected by IW regimes. Total chlorophylls remained constant but chlorophyll a/b ratio increased in Si treatments especially at 10 mM, suggesting Si involvements in stress-adaptive response. Seedlings under 100% IW had the highest relative water content (RWC) and membrane stability index (MSI) of leaves. RWC and MSI decreased by reducing IW regime with no effect of Si application. Leaf P, Mg, and Si levels were higher in Si treatments compared with nontreated seedlings, in contrast to K, Ca, and Na that were unaffected, although root P and K contents were higher at 100% and 80% IW. In conclusion, IW level exhibited detrimental effects on seedling growth; however, a limited effect of Si application.