AbstractEight chemical compounds were evaluated in 13 field experiments to determine if they could ripen sugarcane at the end of the harvest season, May-June 1970, on the humid northern coast (Loíza) and the irrigated southern coast (Aguirre and Mercedita) of Puerto Rico. C.P. 41845 (Monsanto) ripened sugarcane at Loíza and Mercedita when the control plots indicated dropping sucrose and purity values due to rainy weather. There were significant increases with the 2- and 4-pound per acre applications for pol, Brix and sucrose-percent-cane for the mean of the 6-week period after application. At Aguirre, there were no significant increases in sucrose components for individual samples or mean of all sampling dates. The control plots for this trial showed increasing sucrose and purity levels for the 6-week period. Pesco 1815 at 1.5-pound and 60CS16 at 0.5-pound per acre rates gave positive increases in the sucrose components, Brix, sucrose-percent-cane and purity at Mercedita, but not at Loíza. The results suggest that the success or failure of these three compounds to ripen the cane at the various experimental sites may depend on the degree and tendency of maturity of the cane. Cane with low or dropping sucrose and purity levels responded to the ripening compounds, whereas cane with naturally high or increasing sucrose or purity values failed to respond. Gibberellic acid, Dalapon, Silicon, Ethrel 68-250 and Cycocel failed to give significant increases in pol-percent-cane, Brix, sucrose-percent-cane or purity. The experimental techniques of applying sprays with a pneumatic-type tank equipped with a long lance for small-plot experimentation was discussed. To reduce the standard error it is suggested that the number of replications be increased and care taken in selecting plots for uniform stand and with a minimum of lodged cane.
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