Levels and stages of artificial defoliation in the agronomic performance of the cassava crop

Abstract

The cassava crop is susceptible to foliar loss due to several pests, which interfere with the photosynthetic rate, causing large losses mainly to its organ of interest, which are the roots. The objective of this study was to evaluate the agronomic performance of cassava crop following different levels of artificial defoliation at different stages of development. The experiment was conducted in Guaíra-PR, using a randomized block design in a 5 × 5 factorial scheme, with five levels of defoliation in five developmental stages. The levels consisted of 0, 25, 50, 75, and 100% defoliation, and the stages were 45, 90, 135, 180, and 225 days after planting (DAP). The responses of the variable height and plant diameter were inversely proportional according to the interaction of the factors levels and times of defoliation, especially when 100% defoliation was performed at 90 DAP. For root weight, the greatest level of defoliation at 132 DAP resulted in a low yield, whereas for starch deposition in the roots, only the levels had a significant effect for reduction, presenting a linear decreasing effect according to an increase in defoliation. In conclusion, high levels of defoliation between 122 and 132 DAP resulted in greater damage to the root mass; these high defoliation levels independent of the defoliation stage caused the largest losses in the amount of stored starch.