Desfolha na planta de trigo e seus reflexos nas características morfométricas dos grãos

Abstract

Brazil is currently not self-sufficient in wheat production, requiring imports. The loss of leaves is one of the highlighted factors that could affect the productivity of wheat plants. The upper leaves, mainly the flag leaf, are responsible for most of the production of photoassimilates. Therefore, the objective of this work was to evaluate the effect of defoliation on wheat cultivars on their yield components and the physical characteristics of the grains. The experiment was conducted at the Agricultural Sciences Experimental Farm of the Federal University of Grande Dourados, in a randomized complete block design (RCBD) in a 2 x 6 factorial arrangement, with two wheat cultivars (Catuara (CA) and Gralha Azul (GA)) and six levels of defoliation (T0: control - no defoliation; T1: defoliation of the flag leaf; T2: defoliation of the first leaf below the flag leaf; T3: defoliation of the second leaf below the flag leaf; T4: defoliation of the flag leaf and the first leaf below; T5: defoliation of the flag leaf and the second leaf below). The number of spikelets per spike, number of grains per spikelet, number of grains per spike, thousand grains weight, length, thickness, width, and volume of the grains were evaluated. The number of spikelets and the number of grains per spike showed statistical differences between the cultivars, with the highest values found in the Gralha Azul cultivar. The number of grains per spikelet was not influenced by the defoliation levels and cultivars. Grain thickness was influenced by the interaction between cultivars and defoliation levels. Furthermore, the defoliation of the flag leaf reduced the length, width, volume of grains, and thousand grains weight, however, its stability resulted in higher values of these variables. We concluded that the production components were not affected by defoliation, but the morphometric characteristics were affected by it. In relation to cultivars, although Gralha Azul had a greater number of spikelets per spike and grains per spike, it was more sensitive to defoliation levels.