Leaf anatomy of emerald grass submitted to quantitative application of herbicides

Abstract

The aim of this work was to evaluate the selectivity of herbicides applied in post-emergence on Zoysia japonica Steud (Poaceae) and determine associations with the leaf anatomy of this grass. The experimental design was randomized blocks with four replications. The treatments were the application of the herbicides bentazon (720 g ha -1 ), nicosulfuron (50 g ha -1 ), halosulfuron (112.5 g ha -1 ), oxadiazon (875 g ha -1 ) and 2.4-D (698 g ha -1 ), plus a control treatment without herbicide application. Phytotoxicity was assessed every seven days after application (DAA) of the herbicides until the symptoms disappeared. Foliar anatomical analyses of the leaves in the collected grass were conducted until the 35 th DAA. The quantitative characters of the keel and wing region of the blade of Z. japonica were assessed, as well as the biometric characters, which were submitted to an analysis of variance F test, and the averages were compared by Tukey's test at a probability of 5%. The values of the anatomical characters of the foliar blade were tested by cluster analysis. The application of herbicides did not negatively influence the height of the plants but did reduce their dry mass. Toxic symptoms disappeared after 21 DAA, with the only symptoms of injury observed in plants treated with the herbicides oxadiazon and nicosulfuron. In addition, the cluster analysis indicated the formation of a unique discriminatory group. Thus, the results show that the herbicides applied to Z. japonica were selective for the species. Key words: Plant anatomy. Lawns. Selectivity. Zoysia japonica. ResumoObjetivou-se com esse trabalho avaliar a seletividade de herbicidas aplicados em pós-emergência sobre grama Esmeralda -Zoysia japonica Steud (Poaceae), em associação com estudos da anatomia foliar dessa grama. O delineamento experimental foi em blocos ao acaso, com quatro repetições. Os tratamentos constituíram da aplicação dos herbicidas: bentazon (720 g ha -1 ), nicosulfuron (50 g ha -1 ), halosulfuron (112,5 g ha -1 ), oxadiazon (875 g ha -1 ) e 2,4-D (698 g ha -1 ), além de um tratamento controle, sem aplicação de herbicidas. As avaliações de fitointoxicação foram realizadas a cada sete dias após a aplicação dos herbicidas (DAA) até o desaparecimento dos sintomas. Realizaram-se análises anatômicas foliares da grama coletando-se folhas no 35 o DAA. Avaliaram-se os caracteres quantitativos da região da quilha e da asa do limbo de Z. japonica, bem como os caracteres biométricos da grama, os quais foram

Weed Management and Herbicide Selectivity in Ornamental Plants

“…In another study, Marques et al (2017) evaluated the same herbicides and doses of the previous research on bahiagrass and also observed acceptable selectivity of the herbicides halosulfuron (112.5 g ha -1 ), 2,4-D (875 g ha -1 ), and bentazon (720 g ha -1 ) to this species and lower selectivity of the herbicides nicosulfuron (50 g ha -1 ) and oxadiazon (875 g ha -1 ), with more severe injuries only with nicosulfuron application, which led to being considered as non-selective. Thus, most results corroborate those found by Marques et al (2016) for Korean lawngrass.…”

“…The association of herbicide with mulch was studied by Seixas et al (2011), who evaluated the effect of the herbicide pendimethalin (1.5 kg ha -1 ) applied alone and in association with rice husk and sawdust (10,15, and 20 t ha -1 ) for weed control (Alternanthera tenella Colla, Blainvillea rhomboidea Cass, Cenchrus echinatus L., and Commelina benghalensis L.) in Ixora chinensis Lam. Both pre-emergence spraying and herbicide soaking into mulch were used.…”

“…The researchers also report that all chemical treatments were effective for weed control. Marques et al (2016) evaluated the selectivity of the herbicide bentazon (720 g ha -1 ), nicosulfuron (50 g ha -1 ), halosulfuron (112.5 g ha -1 ), oxadiazon (875 g ha -1 ), and 2,4-D (698 g ha -1 ) on Korean lawngrass plants and found that none of them reduced plant height, but reduced dry matter. Visually, only the herbicides nicosulfuron and oxadiazon provided injuries, which dissipated within 21 days after herbicide application.…”