Water regime variability during the flowering phenophase of white and yellow grain maize hybrids and the relation with grain yield

ABSTRACT The impact of low water availability on maize yield depends on the severity of the water deficit and the phenological stage of the crop. The objective of this study was to evaluate the variability of the water regime during flowering in white (GB) and yellow (GA) maize hybrids and its effects on grain yield. The study was conducted under field conditions in a pelic vertisol soil in Celaya, Guanajuato, Mexico. The drought condition of the crop was 75% of soil humidity with a soil water potential of -1.5 MPa. Hydraulic conductivity (Lp), water (Ψr) and osmotic (Ψs) potentials of the roots (during flowering phenophase), grain yield and water productivity were the evaluated variables. As results, significant variability of the water regime variables was obtained among the evaluated hybrids, resulting in variation of grain yield. The white-grain hybrids with the highest Lp were GB4 and GB5 and for yellow-grain GA2 and GA10, all exceeding 347.75 mg m-1 s-1 MPa-1. In some hybrids Ψr and Ψs, decreased to more than -1.85 and -2.80 MPa, respectively, showing positive responsiveness during flowering to the drought condition of the soil. There was positive and significant correlation between Lp x Yield, and highly significant negative correlation between Ψs x Yield. The highest yielding hybrids were GB4 (8000 kg ha-1) and GA2 (7800 kg ha-1). These hybrids will continue to be evaluated for other variables for validation and recommendation for drought conditions. RESUMO O impacto da baixa disponibilidade de água na produtividade do milho depende da gravidade do défice hídrico e do estádio fenológico da cultura. O objetivo deste estudo foi avaliar o regime hídrico durante a floração em híbridos de milho branco (GB) e amarelo (GA) e seus efeitos na produtividade de grãos. O estudo foi conduzido em condições de campo em um solo vertissolo pélico em Celaya, Guanajuato, México. A condição de seca da cultura foi de 75% da humedade do solo com potencial hídrico no solo de -1,5 MPa. As variáveis avaliadas foram condutividade hidráulica (Lp), potencial hídrico (Ψr) e osmótico (Ψs) radicular (durante a fenofase de florescimento), rendimiento de grãos e produtividade da água. Como resultados, obteve-se variabilidade significativa das variáveis do regime hídrico entre os híbridos avaliados, resultando em variação na produtividade de grãos. Os híbridos de grãos brancos com maior Lp foram GB4 e GB5 e para grãos amarelos GA2 e GA10, todos excedendo 347,75 mg m-1 s-1 MPa-1. Em