Dinâmica de populações e fitossociologia de plantas daninhas no cultivo do feijão-caupi e mandioca no sistema corte e queima com o uso de arado

Abstract

Palavras-chave: Vigna unguiculata, Manihot sp., sistema itinerante, aração, comunidade infestante.ABSTRACT -This study investigated the floristic composition of weeds in a burnt area in Zé Doca, Maranhão, during three agricultural years. The preparation of the area at the first crop year (2006/ 2007) was by slash-and-burn for maize cultivation, followed by cowpea. In the second and third crop years, the preparation of the area consisted of plowing for maize cultivation, followed by cassava (2007/2008) and later, by cowpea in rotation with cassava (2008/2009). Weed collection in the cowpea and cassava crops was carried out 30 and 60 days after sowing (DAS) during the first and second agricultural year, respectively, and cowpea crop at 30 DAS in the third crop year with a rectangle (0.5 x 0.3 m) randomly placed in the area. Every launch was conducted to evaluate the aerial parts of the weeds harvested for counting, identification and drying to obtain the phytosociological indices. The slash-and-burn practice reduces the variety and number of weeds. Species with the highest IVI were Imperata brasiliensis, Sida glomerata and Corchorus argutus after slash-and-burn in the cowpea culture; and Juncus sp., Spermacoce verticillata, Aeschynomene americana and Cyperus sp. after plowing in the cassava and cowpea cultures. Secondary vegetation plants occurred after burn, but were reduced over time.

Eficácia e seletividade de herbicidas em cultivares de feijão-caupi

“…Todavia, em áreas sem infestação destas espécies ou outras que por ventura não exerçam boa eficácia, estes herbicidas podem apresentar boa eficácia. Segundo Marques et al (2011), a comunidade infestante na cultura do feijão-caupi varia no decorrer dos ciclos produtivos em razão das alterações das culturas e das práticas de manejo.…”

Eficiência de herbicidas para a cultura do feijão-caupi

“…Mossoró, 2011 1/ Eficiência de herbicidas para a cultura do feijão-caupi (Tabela 5), visto que esses dois tratamentos apresentaram controle eficiente sobre todas as espécies presentes (Tabela 4). No entanto, os tratamentos imazethapyr + fluazifop-p-butyl e bentazon + imazamox + fluazifop-p-butyl, que resultaram em acúmulo de massa seca intermediário, poderiam ser mais eficientes em áreas sem ocorrência da espécie T. portulacastrum, a qual não foi controlada com eficácia pelas respectivas misturas, uma vez que a eficácia e, consequentemente, a escolha dos herbicidas dependem das espécies infestantes, que, segundo Marques et al (2011), variam no decorrer dos ciclos produtivos em razão das alterações das culturas e das práticas de manejo.…”

Floristic and Phytosociology of Weeds in Upland Rice in the Humid Tropics

“…Analysis of the most affected component (density, frequency or dominance) can provide important evidence of how the environmental pressure agent acts against impaired populations. Marques et al (2011), in a phytosociological survey in the humid tropics, have verified that there was a change in the classes and families dominance due to preparation of the soil with the selection of species of difficult control in the cutting and burning system. Therefore, knowledge about the floristic composition and phytosociological structure of weeds in an agricultural crop is an essential condition for the definition of more appropriate management strategies, particularly in regions of the humid tropics, where dynamics of growth and occupation of agroecosystems are very rapid.…”

“…This shows this species adaptation level to the cultivation conditions and its potential to interfere in cultural practices and reduction of upland rice cultivation yield in the humid tropics. Marques et al (2011) have also identified these species as having significant importance in the weed community of cowpea in a cutting and burning system -food culture of great relevance for family farmers who grow it at the end of the rainy season. In the rice crop reproductive phase in Alto Alegre do Pindaré there was also some change in predominance of the species in most areas.…”

“…The cutting and burning system is based on the shallow cutting of secondary vegetation (capoeira), followed by burning and subsequent cultivation of rice in monoculture or intercropped with maize, beans and cassava for two or three years and leaving the area for fallow (Marques et al, 2011).…”