Effects of zinc-enriched amino acids on rice plants (Oryza sativa L.) for adaptation in saline-sodic soil conditions: Growth, nutrient uptake and biofortification of zinc

Abstract

• Zinc-enriched amino acids (Zn-AAC) boosted salt-stressed rice yield. • Zinc tryptophan (ZnTrp) increased physiology and chlorophyll contents. • ZnTrp improved the bioavailability of Zn in soil and plant tissues. • ZnTrp enhanced the fortification and Zn in rice and quality of rice. Soil salinization and its associated problems are becoming a potential threat to the sustainability of agriculture. Deficiency of micronutrients like zinc (Zn) is a common growth limiting factor in salt-affected soils. The current study aimed to evaluate the effects of Zn enriched amino acids (ZnAAC) on the growth, nutrient uptake, and Zn fortification in rice plants under salt stress. Different ZnAAC including Zn glycine (ZnGly), Zn methionine (ZnMet), Zn tryptophan (ZnTrp) and conventional ZnSO 4 were applied at the rates of 8, 10, and 12 mg/kg with three replicates. The results of the current experiment revealed that ZnTrp applied at 12 mg/kg showed the maximum increase in root, shoot, and paddy weight (g/pot), which remained 12.9, 49.0, and 33.9, respectively. Maximum chlorophyll contents, photosynthetic rate, transpiration rate, stomatal conductance, and sub-stomatal carbon dioxide were with the application of ZnTrp to rice grown on salt affected soil. Maximum increase in Zn concentration in soil (391.3 %), roots (251.8 %), shoots (232.9 %), and paddy (287.8 %) were increased with the application of ZnTrp at 12 mg/kg compared to that with control. Maximum decrease in phytic acid in rice paddy was observed with the application of ZnTrp at higher application rate. It is concluded that the application of ZnTrp is an effective remedy to enhance the growth response and Zn fortification in rice grown on salt affected soil.