Effect of zeolite application on phenology, grain yield and grain quality in rice under water stress

Plant growth and grain yield of various upland crops in response to zeolite application have been extensively studied, but little information is available on the impact of zeolite application on rice grown in the lowlands under water stress. A two-year experiment was conducted using lysimeters in the field to evaluate the influence of zeolite application (15 t ha-1) on phenology, grain yield and grain quality in a local rice cultivar (Shennong 9765) under three irrigation regimes (CF, continuous flooding irrigation; IAWD, improved alternate wetting and drying irrigation; and AWD, alternate wetting and drying irrigation). Regardless of water supply, zeolite application significantly increased leaf area index (LAI) at all the measured stages except for tillering, SPAD values at the jointing-booting and heading-flowering stages, photosynthetic rate (Pn) at heading-flowering stage, and grain yield and water use efficiency (WUE). Moreover, zeolite addition significantly increased the head rice rate and decreased the chalk rice rate and chalkiness. The IAWD and CF treatments had similar SPAD values and Pn at the heading-flowering stage, and grain yield, while the AWD treatment significantly reduced those values, relative to the CF treatment. The IAWD and AWD treatments significantly increased WUE, milled rice rate, head rice rate, peak viscosity, and breakdown, but decreased water use, LAI, chalky rice rate, chalkiness, cool viscosity, and setback. These results suggest that the adoption of IAWD with 15 t ha-1 of zeolite application could reduce irrigation water use, increase grain yield and improve grain quality in rice.