Efeito do estresse hídrico sobre o crescimento de cultivares de cana-de-açúcar

• Autor(a) principal: Batista, Evandro Lima da Silveira
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5257
• topic: Agrometeorologia; Cana-de-açúcar; Estresse hídrico; Interação planta-ambiente; Agrometeorology; Cane sugar; Water stress; Plant-environment interaction; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA

The main objectives of the present study were: 1) to evaluate the goodness of fit of growth models to determine the variation of the dry mass for sugarcane, cultivars RB92579, RB867515, RB928064 and RB855453; and 2) determine the growth rates of the mentioned cultivars subjected to different levels of water stress, denoted in the present work as: unstressed (10 kPa), mild (60 kPa), moderate (90 kPa) and severe (120 kPa). Two independent experiments were carried out: the first one under field conditions and the second one in a greenhouse, both located at the Federal University of Viçosa (Brazil). Environmental and plant data were collected from October 26 (2011) to May 18 (2012) for the first experiment and December 18 (2011) to May 22 (2012) for the second experiment. In the first experiment, the growth models (expolinear, logístico and Gompertz) were capable of simulating well accumulated dry matter of the cultivars, during the studied period. Values of the adjusted determination coefficient were above 92.09% for all evaluated models. Based on the adjusted parameters of the expolinear model, it was observed, at the end of the experimental period, that the dry mass was lightly superior for the cultivar RB855453 compared to RB867515, which outperformed the cultivars RB928064 and RB92579. Due to the water stress effect on the growth and accumulated dry mass of sugarcane under greenhouse conditions, it was observed that the sigmoid model with three parameters provided the best fit to the growth and data of plant heights. In the treatments without water stress, the maximum values of culture growth rate (TCC) ranged between 0.22 and 0.31 g°Cd-1, while the maximum values of stem elongation rate (TEC) were between 0.20 and 0.25 cm°Cd-1, regardless of cultivar. In contrast, under severe water xviii stress, the maximum values of the TCC ranged between 0.050 and 0.068 g°Cd-1 and the TEC were between 0.07 and 0.09 cm°Cd-1, also regardless of the evaluated cultivar. For the treatment without water stress, the maximum TCC for the RB867515 cultivar were larger then RB855453, RB92579 and RB928064, corresponding to 7.5, 36.8 and 40.8 %, respectively. In that condition, the cultivar RB867515 reached the maximum TEC only at 1100°Cd, while for the others, the maximum values were observed at 900 °Cd, approximately.