Efficiency of Chemical Ripener Action in Sugarcane. VI. Growth and Qualitative Responses to Polaris as a Function of the Area of Treated Leaf Surface

Abstract

Growth and qualitative effects of Polaris (N,N-bis [phosphonomethyl] glycine) were examined in early-adult sugarcane in which varying proportions of the green leaf surface were treated. The blades of leaf ranks 0 to ⁺4 were treated individually with an aqueous Polaris solution containing 3,000 p/m active material. Treatment areas ranged from 10 to 100% of the receptive leaf canopy. Parameters for growth, juice quality, and tissue sucrose and protein components all indicated that 100% of the green leaf surface must be treated to produce maximum responses. Polaris was growth-stimulatory when applied to only 10% of the leaf surface. Significant but inconsistent qualitative responses were obtained where 10 to 60% of the leaf surface was treated. Acid invertase was the only parameter showing a significant response at the lowest treatment level and th rough the highest treatment level. The implications of these findings for the treatment of field cane are discussed.