Browsing by Author "Takagaki, Michiko"

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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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    Exploration of rainfed rice farming in Uganda based on a nationwide survey: Evolution, regionality, farmers and land
    (African Journal of Agricultural Research, 2013) Haneishi, Yusuke; Okello, Stella E.; Asea, Godfrey; Tsuboi, Tatsushi; Maruyama, Atsushi; Takagaki, Michiko; Kikuchi, Masao
    Based on a nationwide survey of rice growing households, this paper explores how rainfed rice cultivation evolved in Uganda, how diverse it is in different regions of the country, what categories of farmers have adopted it, and how it has been integrated into their traditional cropping patterns. We find that the diffusion of rainfed rice cultivation accelerated at around the turn of this century when upland New Rice for Africa (NERICA) was introduced in the agro-ecological zones receiving annual rainfall of 1000 mm or more. The growth rate of area under rainfed rice cultivation from 2000 to 2009 was 14% year-1 in the lowest zone and as high as 31% year-1 in the highest zone. Rice was grown predominantly by smallholders. Farmers growing rainfed rice, upland and lowland alike, cultivated on average 2 ha of farm land, of which one-third (0.6 ha) was planted to rice, and the sizes of cultivated area and rice planted area of around 70% of farmers were below these averages. In terms of land tenure systems, rice was a crop of more importance in areas where the traditional customary tenure systems still remained, and the incidence of leasehold land tenure was higher for rice cultivation than for other crops.
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    Exploration of rainfed rice farming in Uganda based on a nationwide survey: Regionality, varieties and yield
    (African Journal of Agricultural Research, 2013) Haneishi, Yusuke; Maruyama, Atsushi; Asea, Godfrey; Okello, Stella E.; Tsuboi, Tatsushi; Takagaki, Michiko; Kikuchi, Masao
    Using a nationwide survey of rice growing farmers in Uganda, this study examined how farmers grow rice under rainfed conditions in various agro-climatic zones, and how rainfed rice cultivation performs in terms of yield, and what factors determine the level of rice yield. The study found that Nerica 4 and Supa were the two major varieties planted by rainfed rice farmers, the former in upland and the latter in lowland. High seeding rate, low fertilizer-chemical application and high labor intensity characterized rainfed rice cultivation in Uganda, though distinct regionality existed in fertilize-chemical application and labor intensity. The high marketed ratio of rice produce also characterized rice farming. The estimation of yield functions revealed that rainfall, the amount of seeds and fertilizers applied, lowland and small farmers were positive determinants of rice yield per hectare, that the potential for high yield existed in western regions of the country, and that there were some minor lowland rice varieties that performed better than popular Nerica 4 and Supa. The estimation also revealed that rice plots under the traditional tenure systems yield less, and those under the leasehold system yield more, than those under the formalized freehold and private mailo systems.
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    Rice Green Revolution and Climatic Change in East Africa: An Approach from the Technical Efficiency of Rainfed Rice Farmers in Uganda
    (Agricultural Sciences, 2014) Maruyama, Atsushi; Haneishi, Yusuke; Okello, Stella E.; Asea, Godfrey; Tsuboi, Tatsushi; Takagaki, Michiko; Kikuchi, Masao
    In East Africa where a drastic improvement in food security is an urgent need, rice, a non-traditional crop in most of countries in the region, has emerged as an important food crop that could extend the Green Revolution to the region following the introduction of New Rice for Africa (NERICA) in the early 2000s. Using data collected through a nationwide survey, this paper examines the possibility of rice green revolution by estimating the technical efficiency (TE) of rainfed rice farmers in Uganda and simulates how unfavorable climate changes affect it. The estimated stochastic frontier yield function showed that the mean TE was 65% for lowland and 60% for upland, and that the potential yield of rainfed rice cultivation was as high as 3 t·ha−1. However, the stochastic simulation of rainfall and rice yield revealed that unfavorable climate changes could erase the high potential in crop yield. Rainfed rice cultivation could be a leading sector for realizing Green Revolution in East Africa. It plays a critical role in this process to improve rice farmers’ TE, which is lower in the region than in Asia. Worsening climatic conditions, if occur, make this need even more imperative.
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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.