Interferência de diferentes períodos de corte da parte aérea no desenvolvimento de Digitaria insularis

Abstract

Sourgrass has become a problem in agricultural soils in southern Brazil due to the control difficulty. The regrowth of sourgrass plants is facilitated by the development of a reserve structure known as rhizome and the tolerance to herbicides favored by the production of epicuticular wax. The objective of the present work was to evaluate the development of the sourgrass subjected to four cut dates + control of the plant’s shots after its emergence. Sixty sourgrass plants were grown in a greenhouse in 12 L pots, being cut close to the substrate at intervals of 21, 35, 49, and 77 days after emergence + control without cutting. The green and dry mass of aerial and root parts, plant height, number of leaves, amount of wax in the cuticle, chlorophyll A, B and total and water content in both the aerial and root parts were evaluated. It was possible to observe that sourgrass has an aggressive regrowth capacity, producing a greater number of leaves when the aerial part is cut (as was the case when cut at 21 DAE) than control. Although the cut stimulates the production of leaves, it reduces the height of the plants, the content of chlorophyll a and the green matter of the root system. For this reason, the importance of controlling D. insularis in the first days after the emergence of the crop, to prevent it from having time to develop an expressive root system, thus enabling greater regrowth capacity.