Weed interference on nutrient accumulation in the leaves of cassava under no-tillage or conventional tillage

Abstract

The objective of this work was to evaluate the effect of weed competition on the accumulation of nitrogen and phosphorus in the leaves and on the dry weight of the roots of cassava (Manihot esculenta) in the conventional and no-tillage systems, in two crop cycles. The experiments were carried out in a randomized complete block design, with split-split plots and four replicates. The plots consisted of conventional tillage or no-tillage; the split plots, of the competition or not with weeds; and the split-split plots, of the evaluation periods (0, 25, 50, 75, 100, 125, 150, 175, 200, and 225 days after planting/pruning). In the first cycle, weed competition reduced the accumulation of nitrogen in 82.6 and 81.3% and of phosphorus in 65.7 and 85.3% under conventional tillage and no-tillage, respectively. In the second cycle, the reductions in the accumulation of nitrogen were of 41.1 and 52.4% and of phosphorus of 44.1 and 52.6%, in conventional tillage and no-tillage, respectively. The root dry weight of cassava grown with weed competition showed reductions of 15.8 and 11.2% under conventional tillage and no-tillage, respectively, only in the second cycle. Weed competition reduces the accumulation of nitrogen and phosphorus in the leaves of cassava in the conventional and no-tillage systems in both crop cycles, but reduces the dry matter of cassava roots only in the second cycle.

Weed coexistence periods in cassava varieties

“…Weeds of the Asteraceae and Poaceae families are among the most important plants in the agricultural areas of Paraná. Such a situation was observed in a weed survey conducted in a region close to the site of the present study, in which plants of the Asteraceae family were found to have the highest relative importance (Ramella et al, 2020).…”

“…However, it is noteworthy that the cultivation of cassava in no-till over oat straw presents itself as a sustainable alternative, and may even dispense with the use of herbicides for weed control due to the formation of a physical barrier to the emergence of the seed bank and the release of allelopathic compounds (Otsubo et al, 2012). In addition to improving soil fertility due to nutrient cycling processes, reduction of temperature range and preservation of physical properties in the soil compared to conventional preparation (Gabriel Filho et al, 2000;Fasinmirin & Reichert, 2011;Ramella et al, 2020). These factors may give cassava varieties competitive advantages over the weed community.…”