Weed interference periods in the 'Fécula Branca' cassava

Abstract

-This study aimed to determine the periods of weed interference in the first cycle of 'Fécula Branca' cassava. The experiment was arranged in a randomized block design, with four repetitions. The treatments consisted of eight periods of weed control (25, 50, 75, 100, 125, 150, and 175 days after planting -DAP) and eight periods of coexistence between the weed community and the crop (25, 50, 75, 100, 125, 150, and 175), besides control without weeds and control with weeds until harvest (322 DAP). The predominant weed species with higher relative importance were: Avena sativa, Sorghum halepense, Conyza Canadensis, Euphorbia heterophylla, Raphanus raphanistrum, and Commelina benghalensis. It was concluded that, accepting losses of 1% for root and starch production, the period before interference (PBI) was 66 and 70 DAP; the total period of interference prevention (TPIP) was 88 and 91 DAP and the critical period of interference (CPI) was between 66-88 and 70-91 DAP, respectively. For losses of 5% for root and starch production, the PBI was 87 and 88 DAP, and the TPIP 80 and 81 DAP, respectively; in this case, there was no CPI. Considering the average prices of R$ 218.90 t -1 and R$ 1,191.84 t, paid in 2012 for root and starch production, respectively, and control cost of R$ 300.00 ha -1 , the root and starch production for the period prior to economic loss (WEEPPEL) could be estimated to be 20 and 24 DAP, respectively.Keywords: cassava, Manihot esculenta, weed interference, WEEPPEL.RESUMO -Objetivou-se neste trabalho determinar os períodos de interferências das plantas daninhas no primeiro ciclo da cultura da mandioca Fécula Branca. O delineamento utilizado foi o de blocos casualizados com quatro repetições. Os tratamentos constituíram-se de sete períodos de controle das plantas daninhas (25, 50, 75, 100, 125, 150 e 175 dias após o plantio -DAP) e de sete períodos de convivência entre a comunidade de plantas daninhas e a cultura (25, 50, 75, 100, 125, 150 e 175 DAP), além de testemunha capinada e outra testemunha sem capina, até a colheita (322 DAP). As espécies de plantas daninhas que predominaram e apresentaram maiores índices de importância relativa foram: Avena sativa, Sorghum halepense, Conyza canadensis, Euphorbia heterophylla, Raphanus raphanistrum e Commelina benghalensis. Concluiu-se que, aceitando-se perdas de 1% para produção de raízes e fécula, o PAI foi de 66 e 70 DAP; o PTPI, 88 e 91 DAP; e o PCPI, entre 66 e 88 e 70 a 91 DAP, respectivamente. Para perdas de 5% na produção de raízes e fécula, o PAI foi de 87 e 88 DAP e o PTPI, de 80 e 81 DAP, respectivamente; para este caso, não houve o PCPI. Considerando-se valores médios pagos em 2012 para raízes e fécula de R$ 218,90 t -1 e R$ 1.191,84 t -1

Periods of Weed Interference on Orange Tree Crops

“…Interference is usually evaluated through productivity decreases or through plant growth reduction in response to the competition for environmentally available growth resources, such as CO 2 , water, light and nutrients (Agostinetto et al, 2008). Weed interference causes economic damages to producers, by reducing the productivity and degrading the physical and chemical quality of the harvested product (Fialho et al, 2012;Costa et al, 2013).…”

Weed Interference on Growth and Leaf Nutrient Accumulation in Two Cassava Varieties

“…More competitive varieties provide fast closing of the inter-rows space, blocking the passage of sunlight, which stimulates seed bank germination and weed growth. Thus, Silva et al (2013), found that plants from the variety 'Periquita' in coexistence for 75 DAP with weeds Bidens pilosa, Cenchrus echinatus and Amaranthus spinosus presented 60.9%; 32.6% and 48.6% more total dry mass than the plants from the variety 'IAC-12'. The authors also found that the cassava varieties presented lower dry mass accumulation when in competition with weed species, and the roots were the organs most affected by competition.…”

“…In general, it was found that the smallest accumulation of nutrients in the leaves indicate the need for cassava plants to anticipate the development cycle, which leads to a shorter tuberization period and, consequently, a lower final crop yield. Thus, it is evident that despite the rusticity of the cassava crop, there is a need to manage the weed community, at least in the critical period of the crop, so as not to cause damage to the tuber root production, owing to the competition for soil nutrients (Albuquerque et al, 2012, Costa et al, 2013, A'ihi et al, 2017.…”

Levantamento Fitossociológico De Plantas Daninhas Em Cultivo De Mandioca, No Município De Vitória Da Conquista – Bahia.

“…Essa perda de rendimento da cultura da mandioca relaciona-se com o momento inadequado de controle, às condições ambientais nos locais de cultivo, as características da comunidade daninha, das variedades cultivadas, de seus sistemas de produção e o período de convivência (COSTA et al, 2013).…”