Efeito da palha de cana-de-açúcar no regime térmico do solo e no controle de plantas daninhas
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Data
2016-07-08
Autores
Belapart, Diego [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O atual sistema produtivo de cana-de-açúcar deixa quantidades variáveis de palhada na superfície do solo capaz de provocar supressão de algumas espécies de plantas daninhas, além de modificar as características químicas, físicas e biológicas dos solos. Portanto objetivou-se avaliar o efeito de diferentes quantidades de palha de cana-de-açúcar na emergência de plantas daninhas relevantes para a cultura da cana-de-açúcar, além de produzir informações necessárias para conduzir estudos complementares visando determinar a natureza dos efeitos observados. Para tanto, foram conduzidos três estudos de campo em três épocas distintas do ano avaliando-se os efeitos de diferentes quantidades da palha de cana-de-açúcar (0; 2,5; 5; 10; 15 e 20 t ha-1) sobre o regime térmico do solo em diferentes profundidades e sobre a emergência de nove espécies de plantas daninhas (Ipomoea grandifolia, Ipomoea nill, Ipomoea quamoclit, Brachiaria decumbens, Bidens pilosa, Euphorbia heterophylla, Panicum maximum, Ipomoea hederifolia e Merremia aegyptia) aos 7, 14, 21, 28, 35 e 42 dias após a semeadura (DAS). Os experimentos foram conduzidos em blocos casualizados com quatro repetições. A presença da palha sobre o solo alterou o regime térmico, reduzindo a amplitude térmica do solo, principalmente em menores profundidades. A palha reduziu a emergência de plantas daninhas e a intensidade do efeito é dependente da espécie e da quantidade do resíduo sobre o solo. A interferência da palha reduzindo a germinação de plantas daninhas foi pouco dependente da época do ano e das condições climáticas, sendo possível estabelecer modelos gerais relacionando a quantidade de palha com a porcentagem de emergência, quando a variável dependente foi expressa em porcentagem dos valores observados no tratamento sem palha. Houve grande variação nas quantidades de palha necessárias para reduzir em 50% a emergência das plantas daninhas. B. pilosa e P. maximum, espécies de sementes pequenas, foram as mais sensíveis aos efeitos da palha, enquanto que I. nil, I. hederifolia e M. aegyptia, com sementes maiores, foram as menos sensíveis. A palha de cana-de-açúcar sobre a superfície do solo influenciou na emergência das plantas daninhas. Os resultados indicaram que as dimensões e reservas das sementes são determinantes na definição da capacidade das plantas daninhas emergirem quando o solo está coberto por palha.
The sugarcane has great economic importance to the country. Even in the face of technological advances in the cultivation of sugarcane, interference from weeds still cause many losses. After the adoption of mechanized harvesting the weed management has become more complex, mainly due to varying amounts of straw left on the soil surface. In addition to the suppression effect by some weed species, the straw of sugarcane can also modify the chemical, physical and biological properties of soils. Therefore the aim of this study was to evaluate the effect of different amounts of straw sugarcane germination of weed relevant to the culture, as well as producing information necessary to conduct further studies in order to determine the nature of the effects observed . For that, we conducted three field studies that evaluated the effects of quantities of straw between 0 and 20 t ha-1 on the soil thermal regime and the emergence of nine species of weeds. Three experiments were conducted to the field at different times of the year. The experimental design was randomized blocks, with six treatments and four replications, totaling 24 installments. The treatments consisted of volumes of dry straw cane sugar (0, 2.5, 5, 10, 15 and 20 t ha-1). Each plot consisted of 4 m long and 3 m wide, totaling 12 m². In each were opened three trenches of 1 m2 and 5 cm deep, for sowing of approximately 100 seeds of nine species of weeds. In each trench was used three kinds, the first being Bidens pilosa, Ipomoea quamoclit and Merremia aegyptia; the second heterifolia Ipomoea, Ipomoea nil and B. decumbens and third, Panicum maximum, Ipomoea grandifolia and Euphorbia heterophylla. After sowing of the plants, the straw of sugarcane was evenly distributed as the volumes defined in the treatments. soil temperature assessments were carried out and the emergence of weeds at 7, 14, 21, 28, 35 and 42 days after sowing. The presence of straw on the soil changes the thermal regime, reducing the temperature range of the soil, especially at shallower depths. The straw reduced the emergence of weeds and the intensity of the effect is dependent on the kind and amount of residue on the ground. Interference of straw reducing the germination of weed was little dependent on the time of year and weather conditions, it is possible to establish general models relating the amount of straw with the emergence percentage, when the dependent variable was expressed as a percentage of the values observed in without straw treatment. There was wide variation in straw quantities required to reduce by 50% the emergence of weeds. Bidens pilosa Panicum maximum, small seed species were more sensitive to the effects of straw, while Ipomoea nil, Ipomoea hederifolia and Merremia aegyptia with larger seeds were less sensitive. The straw of sugarcane on soil surface influenced the emergence of weeds. The results indicated that the dimensions and reserves of seed are crucial in defining the capacity of emerging weeds when the soil is covered with straw.
The sugarcane has great economic importance to the country. Even in the face of technological advances in the cultivation of sugarcane, interference from weeds still cause many losses. After the adoption of mechanized harvesting the weed management has become more complex, mainly due to varying amounts of straw left on the soil surface. In addition to the suppression effect by some weed species, the straw of sugarcane can also modify the chemical, physical and biological properties of soils. Therefore the aim of this study was to evaluate the effect of different amounts of straw sugarcane germination of weed relevant to the culture, as well as producing information necessary to conduct further studies in order to determine the nature of the effects observed . For that, we conducted three field studies that evaluated the effects of quantities of straw between 0 and 20 t ha-1 on the soil thermal regime and the emergence of nine species of weeds. Three experiments were conducted to the field at different times of the year. The experimental design was randomized blocks, with six treatments and four replications, totaling 24 installments. The treatments consisted of volumes of dry straw cane sugar (0, 2.5, 5, 10, 15 and 20 t ha-1). Each plot consisted of 4 m long and 3 m wide, totaling 12 m². In each were opened three trenches of 1 m2 and 5 cm deep, for sowing of approximately 100 seeds of nine species of weeds. In each trench was used three kinds, the first being Bidens pilosa, Ipomoea quamoclit and Merremia aegyptia; the second heterifolia Ipomoea, Ipomoea nil and B. decumbens and third, Panicum maximum, Ipomoea grandifolia and Euphorbia heterophylla. After sowing of the plants, the straw of sugarcane was evenly distributed as the volumes defined in the treatments. soil temperature assessments were carried out and the emergence of weeds at 7, 14, 21, 28, 35 and 42 days after sowing. The presence of straw on the soil changes the thermal regime, reducing the temperature range of the soil, especially at shallower depths. The straw reduced the emergence of weeds and the intensity of the effect is dependent on the kind and amount of residue on the ground. Interference of straw reducing the germination of weed was little dependent on the time of year and weather conditions, it is possible to establish general models relating the amount of straw with the emergence percentage, when the dependent variable was expressed as a percentage of the values observed in without straw treatment. There was wide variation in straw quantities required to reduce by 50% the emergence of weeds. Bidens pilosa Panicum maximum, small seed species were more sensitive to the effects of straw, while Ipomoea nil, Ipomoea hederifolia and Merremia aegyptia with larger seeds were less sensitive. The straw of sugarcane on soil surface influenced the emergence of weeds. The results indicated that the dimensions and reserves of seed are crucial in defining the capacity of emerging weeds when the soil is covered with straw.
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Palavras-chave
Alelopatia, Emergência, Ipomoea sp, Saccharum officinarum, Amplitude térmica, Allelopathy, Emergence, Termal amplitude