Efeito da densidade populacional e época de colheita na produção de raízes de mandioca de mesa

Abstract

ResumoEm cultivos tradicionais de mandioca de mesa (Manihot esculenta Crantz), bons rendimentos quanto à produção e qualidade das raízes, são obtidos a partir de oito a dez meses após o plantio. Plantas submetidas à menor competição resultam em maior produção de raízes. O objetivo deste trabalho foi avaliar a densidade populacional como instrumento para a produção precoce de raízes comerciais. O experimento foi desenvolvido no ano agrícola de 2001/2002, utilizando-se a cultivar IAC 576-70, em sete densidades populacionais variáveis de 5.000 e 20.000 plantas ha -1 , com colheitas aos seis, oito, dez, doze, quatorze e dezesseis meses após o plantio. Obteve-se a produtividade máxima de 26,8 t ha -1 de raízes aos 16 meses, estimada por regressão na densidade de 20.000 plantas ha -1 . No entanto, as maiores produções de raízes comerciais ocorrem nas menores densidades populacionais, para todas as épocas de colheita estudadas, devido à menor taxa de descarte de raízes que se observa nas baixas populações. Nas colheitas precoces, aos seis e oito meses, observaram-se as produções comerciais estimadas de, respectivamente, 5,9 e 11,1 t ha -1 com 5.000 plantas ha -1 , e 5,0 e 7,2 t ha -1 com 20.000 plantas ha -1 . Esses resultados demonstram que, baixas densidades populacionais em mandioca de mesa possibilitam colheitas precoces, aos 6, 8 e 10 meses após o plantio, com bons rendimentos comerciais de raízes.Palavras-chave: Espaçamento, precocidade, práticas culturais. AbstractIn sweet cassava production, economic yields of high quality roots are obtained only after a growing season of eight to ten months. In addition, cassava plants under little competition present higher yields per plant. The objective of this work was to study the handling of population densities in the sweet cassava crop, as a tool to obtain high yield of high quality roots in earlier harvests. Seven plant densities, from 5,000 to 20,000 plants ha -1 , were tested with growing cycles of six, eight, ten, twelve, fourteen and sixteen months, in a field trial using the cv. IAC 576-70. Total root yields increased with time, being the highest values obtained with the highest plant densities. It was estimated, with a regression model, a maximum yield of 26.8 t ha -1 , when using 20,000 plants ha -1 and a growing cycle of sixteen months. On the other hand, the highest yields of marketable roots were obtained with smaller plant densities in all harvests, which was caused by lower root discard rate at low populations. The maximum yield was 19.1 t ha -1 in the latest harvest by using 5,000 plants. In earlier harvests, after six and eight months, the marketable yields estimated were 5.9 t ha -1 and 11.1 t ha -1 , when using 5,000 plants; and 5.0 t ha -1 and 7.2 t ha -1 with 20,000 plants. In this way, low population densities for the sweet cassava crop enable earlier harvests, at six, eight and ten months after planting with good yields of commercial roots.

Three decades of cassava cultivation in Brazil: Potentialities and perspectives

“…2) showed that, when changes in plant density (DEN) occurred, there was a positive association with crop productivity (PRO), line spacing (PLS) and spacing between plants (SPL). Results for this influence on productivity were reported in studies found by Cury (2008), Aguiar et al (2011b) and Tironi et al (2019). Density modifications and changes in the spacing between plants or between rows can also adjust the density according to planting conditions under adverse climatic conditions: where the planting will be late, a higher density is used to prevent productivity losses.…”

“…Planting density is one of the most studied variables because of its influence on cassava productivity (Aguiar et al, 2011b). However, there is variation between the densities used throughout Brazil, depending on the purpose of the plant's final use, whether for human, animal or industrial consumption.…”

“…Smaller densities provide lower productivity; however, larger roots are preferable by the market and industry. According to Aguiar et al (2011b), the percentage of commercial roots increased with a reduced planting density, from 33 to 43% of commercial roots in relation to total production, with a reduction in the population from 20,000 to 5,000 plants/ha.…”

“…When the implantation occurred in season <3, including summer and winter, production was low (8.7 t ha -1 ); for season >3, autumn and spring, the level of production was medium, with productivity at 24 t ha -1 . According to Aguiar et al (2011b), high yields can be obtained by combining high population densities and long growing periods; low densities obtain higher commercial yields.…”

Population Structure and Genetic Diversity in Sweet Cassava Cultivars from Paraná, Brazil

“…It is derived from the cross between SRT 797-Ouro do Vale cultivar and the clone IAC 14-18 (Villela et al 1985), is widely distributed in the central southern region of Brazil, and has excellent organoleptic characteristics (Mezette et al 2009) and good agricultural performance in consideration of yield and bacteriosis resistance (Xanthomonas axonopodis pv. manihotis; Aguiar et al 2011).…”