RELATIONSHIP BETWEEN PHYSIOLOGICAL PARAMETERS IN SUGAR CANE (Saccharum spp.) UNDER IRRIGATION SUSPENSION PRIOR TO THE HARVEST

Abstract

In sugar cane (Saccharum spp.), water deficit is necessary during crop maturation to restrict vegetative growth and promote the accumulation of saccharose in the stems, affecting physiological processes and the compensatory response when exposed to stress. The response in photosynthesis rate (A), transpiration rate (E) and stomata conductance (gs) in cultivars Mex69-290 and CP72-2086 subjected to irrigation suspension for 15, 30, 45, 60 and 75 days prior to the harvest was evaluated. The suspension treatments affected the physiological parameters evaluated significantly. The photosynthesis
rate and stomata conductance decreased with the duration of the treatment. The effect of the cultivar was only observed for the photosynthesis rate and transpiration rate. The variance analysis showed a significant interaction between treatments and cultivars, indicating that the response of the cultivar in
relation to the cultivars evaluated depends on the water availability in the soil. A high correlation was observed between E and gs in both cultivars. Under the same conditions of water stress, the Mex 69-290 cultivar showed a higher E (4.69 mmol m^-2 s^-1) than CP72- 2086 (2.92 mmol m^-2 s^-1).