Sugarcane Tolerance to Herbicides Based on the Difference between Treatments

The objective of this work was to evaluate the tolerance of the sugarcane cultivars RB855453, RB845257, SP90-3414, SP90-1638, SP89-1115, SP81-3250, IAC91-2218 and IAC91-5155 at early post-emergence after application of sulfentrazone + diuron + hexazinone; sulfentrazone + metsulfuron-methyl, diuron + hexazinone + clomazone; metribuzin + diuron + hexazinone, diuron + hexazinone + MSMA; and ametryn + trifloxysulfuron-sodium + diuron + hexazinone, using the difference with the paired control. It was assumed that the control paired to the respective treatments can facilitate the evaluation of the cultivars' tolerance to the herbicide treatments. The experiment was arranged in a randomized block design, using the factorial 8 (cultivars) x 6 (herbicides). The plots consisted of six rows of sugarcane, with a central line for the treatment herbicide (TH) and a matched control (TP), with the other lines being used as borders. To check whether the mean differences (TP-TH) did not differ from zero, the following statistics was used: t = (TP-TH)/((QMRes/n)(1/2) or, equivalently, the least significant difference of zero, dms0 (TP TH) = |t/((QMRes/n)(1/2)) |, where QMRes is the mean square analysis of variance (with 47 degrees of freedom and p<0.05, t=2), n represents the number of repetitions of their average, 2 to compare the herbicides in a single cultivar, and 2 x 6 = 12 to compare the overall mean of the cultivars. According to the methodology proposed, the cultivars were tolerant to the association of herbicides without any negative effect on yield and quality of the final raw material, although there were initial differences between the cultivars related to toxicity, chlorophyll content, and plant height.