Indicadores de resposta de variedades de cana-de-açúcar cultivada sob diferentes regimes hídricos

Abstract

In face of demand by renewable biofuels stood up by environmental discussions, the sugarcane crop has become more important for being a great source of raw material for the production of biofuels. The development of varieties adapted to different edaphic-climatic conditions is necessary to support this demand. The objective of this research was to define indicators of response of sugarcane cultivated under water-restriction conditions in the semiarid region of northern Minas Gerais. Plant height, stalk diameter, SPAD index, foliar relative water content, maximum quantum efficiency of photosystem II, photosynthetic rate, stomatal conductance, and transpiration rate of three varieties under three water regimes were weekly evaluated during the tillering phase, in a pot experiment. There was interaction between the days of evaluation and water regimes for maximum quantum efficiency of photosystem II and stomatal conductance. There was a significant difference among the days of evaluation for plant height, SPAD index, foliar relative water content, photosynthetic and transpiration rate. There was a significant difference among varieties only for plant height. The indicators of maximum quantum efficiency of photosystem Il and stomatal conductance should be utilized for distinction of sugarcane varieties with tolerance to drought.