Análise de trilha para componentes do rendimento e caracteres agronômicos de trigo sob desfolha

The objective of this work was to evaluate the influence of yield components and plant characters in grain production, in wheat under defoliation, through correlations decomposition using path analysis. The experiment was accomplished in Vicosa, MG, Brazil, in 2004. The treatments consisted of three levels of defoliation and a control, with three wheat varieties - Anahuac, BRS 207 and BR 24 -, with four replicates. Defoliation was carried out by removing the blade of flag leaves from the second and third top leaves. The following parameters were evaluated: grain yield, hectolitric weight, one thousand-grain weight, number of spikes per plot, number of grain per spike, culm dry biomass, spike-straw dry biomass, total dry biomass, grain yield per spike, total dry biomass of individual culm, straw dry biomass of individual spike and total dry biomass per individual plant. The reduction in culm dry biomass led to lower losses of grain yield because of the higher remobilization of photoassimilates with defoliation. Thousand-grain weight and number of grain per spike were the main yield components. The direct selection for these characters is an efficient strategy to increase grain yield in wheat under defoliation.