Speakers - AFHWC2025

Abstract

The decline in water availability as a result of climate change and the negative impact of chemical fertilizer have posed a significant challenge on the sustainability of rice production through continuous flooding practice. This study assessed the effect of Azolla - an organic biofertilizer, and its combination with NPK fertilizer on growth, yield, water-use efficiency, and nutritional composition of lowland rice (NERICA L-19) under Continuous Flooding (CF) and Alternate Wetting and Drying (AWD) irrigation systems. The experiment was set up in a 2×2 factorial design with four replicates. Irrigation included CF and AWD while soil amendments were 100 kgN/ha Azolla (AZ), 50 kgN/ha Azolla + 50 kgN/ha NPK (AZ + NPK) and 100 kgN/ha NPK (NPK). Data collected on plant height, leaf area, chlorophyll content, tiller number, yield components and proximate composition were analyzed with two-way ANOVA and means separated with DMRT at p<0.05. The result of this study showed that irrigation had no significant effect on yield and agronomic attributes of NERICA L-19; however, significant variations in the use of soil amendments under CF and AWD. AWD produced a comparable yield with CF but saved 49.8% of total water usage.Except for plant height, the single application of Azolla decreased number of tiller (36% and 36%) and leaf area (53% and 54%) compared with NPK under CF and AWD, respectively. Moreover, AZ reduced grain yield by 42% and 31% compared with NPK under AWD and CF, respectively; meanwhile, AZ+NPK produced comparable yield under AWD and increased (p<0.05) yield by 27% under CF when compared with NPK. Increased yield with the use of AZ+NPK under AWD and CF was attributed to significant increase in the production of superior spikelets while other yield components (1000 grain weight, spikelet/panicle, inferior spikelets and percentage sterility) were not significant. AZ+NPK increased superior spikelets by 11% and 5% under AWD and by 31% and 14% under CF compared with AZ and NPK, respectively. Also, AWD increased WUE of NERICA L-19 by 59% compared with CF. On average, AWD increased ash, crude fibre, crude protein of NERICA L-19 by 17.6%, 20.3%, 21.5%, respectively and decreased its carbohydrate by 7.5% compared with CF. Notably, AZ+NPK significantly increased crude protein by 36% and 33% compared with AZ and NPK, respectively under AWD. In conclusion, the use of Azolla in combination with NPK fertilizer reduced the use of chemical fertilizer for lowland rice cultivation in both continuous flooding and alternate wetting and drying irrigation methods without compromising yield and rice nutrition.