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

Martios Ecco; Antônio Carlos Torres da Costa; José Barbosa Duarte Júnior; Augustinho Borsoi; Milciades Ariel Melgarejo Arrúa

doi:10.9755/ejfa.2019.v31.i11.2033

Authors

Martios Ecco Dr. of the course of Agronomy of the Pontifical Catholic University of Paraná, Toledo campus, Avenida da União, 500, 85902-532, Toledo, Paraná, Brazil
Antônio Carlos Torres da Costa Dr. of the Agronomy course of the State University of Western Paraná, Marechal Cândido Rondon campus, Pernambuco Street, 91, 85960-000, Paraná, Brazil
José Barbosa Duarte Júnior Dr. of the Agronomy course of the State University of Western Paraná, Marechal Cândido Rondon campus, Pernambuco Street, 91, 85960-000, Paraná, Brazil
Augustinho Borsoi Dr. of the Agronomy course of Assis Gurgacz College, Cascavel campus, Avenida das Torres, 500, 85806-095, Paraná, Brazil
Milciades Ariel Melgarejo Arrúa Dr. of the Agronomy course at the National University of Canindeyú, Salto del Guairá campus, Paraguay

DOI:

https://doi.org/10.9755/ejfa.2019.v31.i11.2033

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.