Abstract
ABSTRACT: The selection of wheat genotypes according to their drought tolerance is essential to off-season cultivation. The objective of this work was to characterize wheat genotypes through yield and components, morphological characteristics under water stress, and irrigated water use efficiency in the Cerrado region in Brazil. Genotypes were planted during the winters of 2016 and 2017 since there is no precipitation during this season and water levels can be measured. They were then submitted to four water regimes: WR1, WR2, WR3, and WR4, representing 100 %, 83 %, 50 %, and 30 % of evapotranspiration replacement. The following variables were evaluated: peduncle length (PL), number of ears m−2 (NE m−2), hectoliter weight (HW), thousand grain weight (TGW), drought resistance index (DRI), irrigated water use efficiency (IWUE) and yield. Most variables showed correlation with yield and can be a useful tool for breeding programs. PL and HW were best correlated with yield. BRS 264 (irrigated biotype) was productive in treatments receiving the greatest number of irrigation treatments. Given that WR1 registered the highest water level, it was not expected that the rainfed biotype (BR18) would show a higher yield than an irrigated biotype (BRS254). BRS404 (rainfed biotype) was the most productive under moderate stress treatment (WR3). Alianca (rainfed biotype) showed a higher yield under severe stress. Rainfed biotypes presented a higher DRI than the irrigated ones. These genotypes can be used as a reference in breeding programs under each water regime in which their performance was outstanding. None of the variables studied contributed to the selection of the most efficient wheat genotypes in the IWUE.
Highlights
In Brazil, wheat is cultivated mainly in the southern region, and represents 91 % of national production (CONAB, 2017)
The plots corresponded to ten wheat genotypes
The effect of genotypes × years and water regime × years interactions were significant at 0.01 % probability using the F test, indicating different responses of the genotypes and water regimes to environmental conditions, which was expected for quantitative traits
Summary
In Brazil, wheat is cultivated mainly in the southern region, and represents 91 % of national production (CONAB, 2017). This scenario has marked consequences for the stabilization of wheat production since climate instability has exposed the high vulnerability of the supply of wheat directed to domestic consumption in Brazil. In the Brazilian Cerrado biome, wheat is cultivated in two seasons: (1) in winter under irrigation and (2) in summer under rainfed conditions. Under conditions of irrigation plants should have water use efficiency (WUE). Cultivation during summer at the end of the rainy season results in wheat being sown during the off-season, and the main limitation is the dry spells, which require drought tolerant (DT) plants
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