Browsing by Author "Matsumoto, Shunsuke"

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    Effects of plant density on the performance of selected African upland rice varieties
    (African Journal of Agricultural Research, 2017) Matsumoto, Shunsuke; Tsuboi, Tatsushi; Asea, Godfrey; Miyamoto, Kisho; Maruyama, Atsushi; Takagaki, Michiko; Kikuchi, Masao
    The effects of plant density on yield and yield components in upland rice cultivation were examined by conducting a series of field experiments in Central Uganda, using three African and one Japanese improved upland rice varieties. The estimation of plant-density response functions with respect to yield components and yield revealed that an increase in plant density significantly decreased the number of panicles per hill, number of spikelets per panicle, and 1000-grain weight, and significantly increased the number of panicles per square meter. The percentage of filled grain was not affected by plant density. Compared to the Japanese variety, the three African varieties were characterized by more numbers of panicles/hill, less numbers of spikelets/panicle, higher grain-filling ratio and lighter 1000-grain weight, but differences in the degrees of response to plant density were less distinct between them. Rice yield increased in the range of plant density tested, though the marginal increase in yield due to an increase in plant density by 1 hill/m2 diminished from 100 kg/ha at the plant density of 11 hills/m2 to 30 kg/ha at 33 hills/m2. No significant differences were found among the four varieties for the level of yield as well as for its degree of positive response to plant density. The yield components that determined the increase in yield were the number of panicles per square meter and the number of spikelets per panicle, or combined together, the number of spikelets per square meter, which was estimated to reach the maximum at the plant density of 35 hills/m2. When the differences among the treatments in the costs of seeds and weed-control were considered, the optimum plant density was found to be 22 hills/m2 (plantspacing of 30 cm × 15 cm), lower than the plant density that gives the maximum yield.
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    Water Response of Upland Rice Varieties Adopted in Sub-Saharan Africa: A Water Application Experiment
    (J Rice Res, 2014) Matsumoto, Shunsuke; Tsuboi, Tatsushi; Asea, Godfrey; Maruyama, Atsushi; Kikuchi, Masao; Takagaki, Michiko
    Whether a rice Green Revolution in sub-Saharan Africa becomes a reality critically hinges on how far productive upland rice cultivation diffuses in the region. In order to quantify the drought tolerance, the rate of water response and the contribution of yield components to changes in yield due to water availability of upland rice varieties used in sub-Saharan Africa, we conducted water application experiments in Namulonge, Uganda, using NERICA 4, NERICA 10, NARIC 2 and Yumenohatamochi, with five different levels of water application. We found that the NERICA varieties were most drought tolerant, followed by NARIC 2. Yumenohatamochi did not withstand the lowest amount of water application of 378 mm. The results suggested that the minimum water requirement was around 311-400 mm per season for the three varieties used widely in East Africa, and around 420-600 mm for Yumenohatamochi, an upland variety in Japan famous in its drought tolerance. It was estimated that an additional water application of 1 mm increased rice yield by 11-12 kg /ha for the upland varieties tested. The high water response of upland rice was brought about by high water response of four yield components, among which the rate of grain filling contributed most to the increase in yield, followed by number of panicles/m2, number of grains per panicle and 1000 - grain weight, in the order of the degree of contribution, for all the varieties tested.