Effect of high rates od 2,4-D herbicide on lodging and grain yield of maize hybrids | Utjecaj visokih doza 2,4-D herbicida na polijeganje i prinos zrna hibrida kukuruza

Previous research indicated that maize hybrids differ in their susceptibility to applied herbicides. The aim of this study was to determine the effect of recommended and high rates of 2,4-D herbicide on the grain yield of maize hybrids. Herbicide treatments consisted of the recommended (1,5 L/ha) and high rates (3,0; 6,0 i 9,0 L/ha) of 2,4-D herbicide compared to untreated (control) plots. The effects of 2,4-D herbicide were investigated on three maize hybrids (Clarica, Bc 288B and Bc 354) in a weed-free maize crop. Crop damages caused by the high rates of 2,4-D herbicide were observed as plant lodging which occurred late during vegetation (around tasseling) and was associated with stormy weather. The application of high rates of 2,4-D herbicide did not affect the number of barren and broken plants. Hybrid Bc 354 had the highest number of lodged plants and consequently the smallest grain yield following the application of high rates of 2,4-D herbicide. In contrast, hybrid Bc 288 did not increase the number of lodged plants or reduce grain yield even after applying the highest (9,0 L/ha) 2,4-D herbicide rate. Hybrid Clarica showed an intermediate response to the application of high 2,4-D herbicide rates. Increased number of lodged plants following high 2,4-D herbicide rates significantly reduced the number of grains on ear, while it had no effect on 1000-grain weight. Significant interaction existed between hybrids and herbicide treatments for grain yields and number of lodged plants. All hybrids produced similar grain yields in untreated plot. However, following the application of high 2,4-D herbicide rates, more susceptible hybrids Bc 354 and Clarica had more lodged plants, and consequently smaller grain yields than the more resistant hybrid Bc 288. Research findings demonstrate that important crop damages and grain yield losses might be observed on maize hybrids following the application of the double than recommended rate of 2,4-D herbicide.