Evaluating of abiotic stress tolerance-inducing substances on the growth, physiology and yield of rice (Oryza sativa L.)

Abstract

Moisture stress due to delayed onset of monsoon, drought or frequent dry spell is one of the major abiotic stresses that affect rice production in Tamil Nadu. It reduces the yield of rice up to 85 % based on its severity. The foliar application of abiotic stress tolerance inducing substances may aid in mitigating stress-induced damages and increase the yield of rice plants. Salicylic acid, ZnSO4, gibberellic acid, humic acid, pink pigment facultative methylotrophs (PPFM), etc. are reported to increase antioxidant enzyme activities and resistance to drought stress however, its effects on crops were location specific. Field experiments were conducted at Annamalai University Experimental Farm, Annamalainagar, Cuddalore District in Cauvery Delta Zone of Tamil Nadu during “Kuruvai” and “Nanvarai” (Kharif and Rabi) seasons of 2021 and 2022 to study the effect of foliar application of stress tolerance inducing substances on the performance of transplanted rice under moisture stress condition. The experiment was laid out in randomized block design (RBD) with 12 treatment combinations including control; Recommended dose fertilizer (RDF) with + acute soil drying + water spray/ KNO3 @ 2% and ZnSO4 @ 0.5% two foliar sprays/ salicylic acid @ 200 ppm/ gibberellic acid @ 40 ppm/ humic acid @ 0.2%/pink pigment facultative methylotrophs (PPFM) @ 2% and was replicated thrice. Among the treatments, application of recommended dose of fertilizer (120 kg N, 40 kg P2O5 and 40 kg K2O/ha) along with KNO3 @ 2% and ZnSO4 @ 0.5% at panicle initiation and 15 days after first spray and humic acid @ 0.2% at booting stage and 15 days after first spray (flowering stage) increased the plant height of 41.01%, dry matter production of 84.70%, leaf area index of 94.25%, number of productive tillers/m of 32.43%, number of filled grains/panicle of 39.14%, reduced unfilled grains /panicle of 368.23%, increased grain yield of 87.23% and straw yield of 82.57% and benefit cost ratio of 1.86.