On-farm multi-location evaluation of occurrence of drought types and rice genotypes selected from controlled- water on-station experiments in Northeast Thailand

Abstract

Rainfed lowland rice is the most common crop ecosystem in Northeast Thailand and varieties well adapted to drought-prone environments are required. On-farm multi-location experiments were conducted for 3 years to determine the drought type commonly developed, to identify genotype by environment interaction for rainfed lowland rice and to examine whether genotypic variation in these experiments was related to that in on-station controlled water- environment screening experiments conducted previously (Monkham et al., 2015). Among 32 on-farm experiments, 4 experienced continuous drought with no standing water during the whole growing season, and 3 of them all in high toposequence positions died before maturity. For the remaining experiments, both intermittent and terminal droughts were common, while some experiments developed early season drought and delayed transplanting but resulted in no apparent yield penalty. The first set of multi-location experiments consisted of 14 experiments in 6 provinces in Northeast Thailand across 2 years with 24 common genotypes. Mean grain yield of 13 environments that were harvested was 2300–3900 kg ha and no severe drought developed at any environment. While main effect of genotype was not significant for grain yield, genotype by environment interaction was significant, and the results of clustering analysis identified 3 environmental groups and 3 genotype groups that explained the main source of the genotype by environment interaction. The genotypic variation obtained in the on-farm multi-location experiments in one environmental group of low yielding environments was correlated with that obtained under earlier intermittent drought selection experiments on-station. The results also indicate the usefulness of screening genotypes based on short delays in the intermittent drought conditions on-station. A second set of multi-location experiments conducted throughout Northeast Thailand to test the performance of four genotypes selected from the first set of multi-location experiments confirmed that these genotypes outperformed the popular variety KDML105. The present study confirmed the usefulness of initial screening under intermittent drought conditions conducted on research stations followed by further on-farm selection. It is suggested that on-station selection experiments should target yield levels representative of on-farm yield levels