Response of Hybrid Rice (Oryza Sativa L.) Varieties to Fertilizer Application under System of Rice Intensification in Kirinyaga and Kisumu Counties, Kenya
Mbatha, Nicholas Wathome
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Kenyan rice farmers have continuously obtained low yields, this has been credited to poor agronomic practices and use of low quality inbred rice varieties. To alleviate the potential catastrophes and challenges of changing climate and improving rice production, there is need to evaluate productivity of improved rice seeds under alternative production systems such as the system of rice intensification (SRI) using a combination of organic (Evergrow) and inorganic fertilizer (Sulphate of ammonia). To address the challenge, the study had four specific objectives; (a)To determine the growth and tillering ability of the two hybrid rice varieties under System of Rice Intensification (SRI) fertilizer practices, (b) To establish the yield components and grain yield of hybrid rice varieties under (SRI) fertilizer practices. (c)To establish the harvest index of the two hybrid rice varieties under SRI fertilizer practices. (d)To determine the quality of the hybrid rice varieties under SRI fertilizer practices. The field experiment was conducted in Mwea and Ahero study sites. The experimental layout was Randomized Complete Block Design (RCBD) in split plot arrangement with the main plots being organic fertilizer at a rate of 2.5 t/ha Evergrow, 200 kg/ha of Sulphate of ammonia, 2.5 t/ha Evergrow + 200 kg/ha Sulphate of ammonia (SA), 2.5 t/ha Evergrow +100 kg/ha Sulphate of Ammonia and the control where no basal fertilizer was applied while the sub-plots were the two hybrid varieties -Arize Tej Gold, Arize 6444 Gold and a local check (IR2793-80-1). Each of the treatments were then replicated three times. Data collected included plant height, number of tillers, days to 50% and 100% flowering, unproductive tillers, number of grains per plant, harvest index and grained yield per hectare were recorded during the experimental period. Amylose and crude protein content of the grain was determined after final harvest. The collected data was subjected to ANOVA using SAS software version 9.2 and significance differences between means were separated using LSD at 5 % level of probability. The results revealed significance differences (P≤0.05) on the parameters evaluated as an influence of the fertilizer combinations and used varieties. The control without fertilizer treatment in the variety Arize Tej Gold took the shortest time to 50% flowering recording 78 days and 92 days in Mwea and Ahero respectively. The IR2793-80-1 variety without fertilizer had the least stand count with 16 and 17 counts in Mwea and Ahero respectively. Significance differences were also observed in grain yield in the two study sites with Arize Tej Gold at Evergrow+100kg/ha SA having the yield of 6.37t/ha in Mwea and 4.37 t/ha in Ahero. The grain quality of the rice varieties under the SRI treatments differed significantly on the amylose and protein contents where 2.5 t/ha of organic fertilizer plus 100 kg/ha SA had the highest with 28.77% amylose and 10.58% protein. The application of 100 kg/ha of SA and organic fertilizer leads to higher yields which are not significantly different from that of the doubled rate of the inorganic fertilizer. The 2.5 t/ha Evergrow+100 Kg/ha SA fertilizer SRI practice will lead to the highest growth and tillering of the rice varieties. The study highly recommends the 2.5 t/ha Evergrow+100 Kg/ha SA fertilizer SRI practice under the improved variety which will lead to realization of the potential grain yield.