Stress physiology and metabolism in hybrid rice. I. Organic manures improve physical soil characteristics and drought tolerance

Abstract

ABSTRACTThe present era is witnessing a serious water crisis affecting rice (Oryza sativa) productivity adversely. Therefore, with the objective of minimizing crop failure under limited water supply the effects of organic manures were compared with inorganic fertilizer for changes in soil physical characteristics, morpho-physiological traits and drought resistance of hybrid rice NDRH-2. Accordingly, one level each of green manure and compost (7.5 t ha−1) was applied supplemented with chemical fertilizers to bring them nutritionally at par with inorganic fertilizer treatment. Organic manures minimized the adverse effect of drought on plant height during a 10-day soil-drying cycle. Organically fertilized treatments enhanced plant sustenance by 4-7 days during drought compared with that fertilized inorganically. Sustenance enhancement was probably due to increased soil moisture-holding capacity [26% to 27.4% in organically fertilized soil (OFS) against 22.2% in inorganically fertilized soil (IFS)] because of decreased soil bulk density (1.20g mL−1 OFS against 1.42 IFS) and soil penetration resistance (500 to 560 kPa OFS against 800 kPa IFS). The organic manures significantly increased leaf water potential (−16 to −18.5 bars OFS against −25 bars IFS), relative water content (84 to 85% OFS against 78% IFS), cell viability (OD 0.290 to 0.352 OFS against 0.165 IFS), membrane stability (83 to 87% OFS against 75%IFS), chlorophyll (10.06 mg g−1 dry weight OFS against 9.42 IFS) and reduced leaf injury (score 3 to 4 OFS against 5 IFS) causedby drought. Hence, farmers living in drought-prone regions, are advised to practice organic farming using organic manures for a successful rice crop in event of scanty rainfall.