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, W880-9-32-1-1-12-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). W880-9-32-1-1- 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.