Soil moisture induced genotype-by-environment interaction for root volume of upland rice

Department of Crop Production, Faculty of Agricultural Production and Renewable Resources, College of Agricultural Sciences, Olabisi Onabanjo University, Yewa Campus, Ayetoro, Ogun State, Nigeria (1,2,3)

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Sixteen rice genotypes comprising established cultivars, recent releases and breeding lines were established in the greenhouse under different moisture levels, obtained from a combination of the amount and number of times of moisture application, to study genotype-by-environment interaction (GEI) for root volume (RV), and also probe into the level of moisture imposition, that would be adequate for screening of genotypes for response to soil moisture stress. Across the simulated environments, WAB 880-9-32-1-1-12-HB had the largest root volume of 8.71 cm3, whereas ITA 257 had the lowest (4.89 cm3). Genotype (G) accounted for significant (P < 0.001) 10.6%, environment (E) (P < 0.001) captured 79.0%, and GEI (P < 0.001) 10.4% of the total sum of squares. The GGE biplot captured 82% of the G+GE and clustered the environments into two groups, with OS 6 being the best for RV in the rainfed environment (E10). WAB 880-9-32-1-1-12-HB recorded the best RV under environments with adequate to limited moisture, but was less stable, and recorded grain production (13.5 g/plant) close to the best mean of 16.0g/plant by ITA 150 and 14.1 g/plant by IRAT 170. Environments were generally positively correlated with vegetative and yield traits, but E2 (100% moisture requirement applied once in two weeks) was more representative of the screening condition while E10 (rainfed) was highly discriminating, and would be appropriate for discarding genotypes with poor RV. Overall, E1, E2, E4 and E7 were identified as moisture conditions that are appropriate for selection of genotypes for general adaptation for RV within the overall goal of developing drought tolerant rice.

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