RESUMOEste trabalho foi desenvolvido com o objetivo de realizar triagem primária para caracterização da tolerância de variedades SP e CTC de cana-de-açúcar à aplicação de dez herbicidas comumente recomendados para manejo de plantas daninhas nesta cultura. Dois experimentos foram desenvolvidos com esquema fatorial entre variedades de cana-de-açúcar e onze tratamentos herbicidas. No primeiro experimento utilizaram-se sete variedades SP (fatorial 7 x 11): SP80-1842, SP80-3280, SP83-2847, SP87-344, SP87-396, SP89-1115 e SP90-3414. No segundo experimento, foram avaliadas seis variedades CTC (fatorial 6 x 11): CTC1, CTC2, CTC3, CTC4, CTC5 e CTC6. Os tratamentos herbicidas aplicados em pós-emergência inicial foram: ametryn, ametryn + trifloxysulfuron-sodium, clomazone, diuron + hexazinone, isoxaflutole, imazapic, 2,4-D, tebuthiuron, sulfentrazone, MSMA e testemunha sem aplicação. Avaliou-se massa fresca, altura, teor de clorofila (índice SPAD) e perfilhamento, todos em termos percentuais relativos à testemunha sem aplicação. Constatou-se tolerância diferencial das variedades de cana-de-açúcar aos herbicidas comumente utilizados na cultura. As variedades SP80-3280 e CTC2 foram as mais tolerantes aos tratamentos herbicidas, podendo ter esta característica explorada em programas de melhoramento genético.Palavras-chave: índice SPAD, herbicidas, fitotoxicidade, Saccharum.
ABSTRACT
DIFFERENTIAL TOLERANCE OF SUGARCANE VARIETIES TO HERBICIDE STRESSThis work was carried out with the objective of screening for tolerance response of SP and CTC sugarcane varieties to application of ten herbicides commonly recommended to weed management in this crop. Two trials were evaluated with factorial design between the sugarcane varieties and eleven herbicide treatments. In the first experiment, seven SP varieties were used (factorial 7 x 11): SP80-1842, SP80-3280, SP83-2847, SP87-344, SP87-396, SP89-1115 and SP90-3414. In the second experiment, six CTC varieties were evaluated (factorial 6 x 11): CTC1, CTC2, CTC3, CTC4, CTC5 and CTC6. The post-emergence-applied herbicide treatments were: ametryn, ametryn + trifloxysulfuron-sodium, clomazone, diuron + hexazinone, isoxaflutole, imazapic, 2,4-D, tebuthiuron, sulfentrazone, MSMA and check without application. The variables evaluated were: fresh mass, height, SPAD index and tillering: Valves here considered as relative percentage to the untreated control. Differential tolerance of sugarcane varieties was observed regarding to application of the tested herbicides. SP80-3280 and CTC2 were the most tolerant varieties to herbicide application, and might have this characteristic exploited by sugarcane breeding programs.
