Desempenho agronômico e fisiológico de híbridos de milho cultivados com e sem restrição hídrica

Abstract

The objective of this study was to evaluate the effects of water restriction during the pre-flowering period of maize hybrids. The study was carried out at the Experimental Farm of Embrapa Milho and Sorgo, in Nova Porteirinha-MG in 2017. Two field experiments were carried out simultaneously, one with and the other without water restriction. In the experiment without water restriction, the crop was irrigated normally, until reaching the physiological maturity of the grains. In the experiment with water restriction, irrigation was established from the pre-flowering period until the end of the crop cycle. In each experiment, the treatments were four maize hybrids, two sensitive (BRS 1010, BRS 1040) and two tolerant (BRS 1055 and DKB 390) to the water deficit. The experiments were installed in a randomized complete block design with four replications. The relative content of chlorophyll (SPAD), chlorophyll fluorescence (Fv/Fm), stomatal conductance (Gs), plant height (PH), spike insertion height (SIH), leaf area index (LAI), root angle (RA), interval between male and female flowering (ASI), lodged and broken plants (LP + BP), plus production components ear length (EL), ear diameter (ED), number of grain rows (NGR), number of grains per row (NGPR), grain weight (GW), weight of 100 grains (W100G), total number of spikes (NS), ear index (EI), shoot dry weight (SDW), grain yield (GY) and water use efficiency (WUE). It was verified that the variables SPAD, Fv/Fm and IAF are good morphophysiological indicators for selection of drought tolerant maize. Water restriction during pre-flowering reduced GY from 62.92 to 86.19%. Maize hybrids, when subjected to water restriction, have statistically similar GY. The hybrid DKB 390 has higher GY and WUE and lower number of LP + BP under adequate irrigation conditions, without water restriction.