Effect of source and application rate of organic fertilizers on grain yield and quality of local and improved rice (Oryza sativa L.) cultivars

To study the response of Hashemi (local) and Gilaneh (improved) rice cultivars to the application of different sources and levels of organic fertilizers, a field experiment was conducted using a randomized complete block design with three replications in 2018-2019 and 2019-2020 cropping seasons in research field of Rice Research Institute of Iran (Rasht), Iran. Experimental treatments include poultry manure (2.5, 5 and 10 ton.ha-1), cow manure (5, 10 and 20 ton.ha-1), sheep manure (10, 20 and 40 ton.ha-1), and two control treatments including chemical fertilizers and no-fertilizer. Traits measured included plant height, number of tiller.plant-1, number of fertile tiller.plant-1, number of panicle.m-2, grain yield as well as amylose content and gelatinization score. The results showed that the effect of organic fertilizers was significant on yield components and grain yield of rice cultivars. Application of 20 ton.ha-1 of cow manure increased plant height (142 cm), number of fertile tillers (14), number of panicle.m-2 (240) and grain yield (3643 kg.ha-1) in Hashemi cultivar and also increased plant height (134 cm), number of fertile tillers (17), number of panicle.m-2 (252) and grain yield (4760 kg.ha-1) in Gilaneh cultivar. Experimental treatments had a significant effect on the gelatinization score of rice grains. The highest grain yield obtained in the treatments of 20 ton.ha-1 of cow manure and Hashemi cultivar (3670 kg.ha-1). The results of this study showed that the application of 20 ton.ha-1 of cow manure increased grain yield by 60 and 64%, in comparison to control treatment of no-fertilizer, and compensated of 86 and 88% of grain yield in Hashemi and Gilaneh rice cultivars, respectively, as compared to the treatment of chemical fertilizers.