Performance of promissing sugar cane genotypes using physiological and biometrical tools

The cultivation of the sugar cane in Brazil is a major source of income for agriculture, especially in the Northeast. Thus, the present study aimed to evaluate four genotypes of sugar cane using biometric and physiological indicators in a protected environment. The study used a completely randomized design with four treatments (genotype 698B, 712B, 260B and 3B), four replications and one plant as useful plot. The seedlings were transplanted at 45 days to vessels of 18 dm3. At 154 days after transplanting, were analyzed the following variables: Fluorescence of the chlorophyll a, levels of chlorophyll a, b and total, proline contents, quantum yield (PS2), photochemistry quenching (qP), nonphotochemical quenching (qN), leaf temperature (TFO), main plant height (PH), culm diameter (DC), number of leaves (NL) and leaf area (LA). The evaluations were conducted in the period between 10:30 and 12:00 in the morning. In conditions of field capacity genotypes showed no statistical difference for the parameters of levels of chlorophyll a, b and total, photochemical efficiency of photosystem II, leaf temperature. For the 712B, proline contents differentiated itself statistically from the others, showing higher levels. The genotypes also differ statistically with regard to the main plant height (PH), number of leaves (NL) and leaf area (LA), standing out the 698B 3B in the number of leaves and leaf area, while the 712B and 260B had lower values for these parameters. Genotypes 3B and 698B are the most promising for the improvement program.