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| Author(s): |
Nagilla Moraes Ribeiro
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Jaboticabal. 2020-12-23. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2020-10-30 |
| Advisor: | Leonardo Bianco de Carvalho |
| Abstract | |
The intercropping of corn-brachiaria has consolidated itself over the years as a viable and productive technique, allowing high waste production and has the potential to reduce weed infestation. The application of underdoses of selective herbicides to the corn crop is an alternative to suppress the initial growth of forage, avoiding losses in both yield and grain quality. The presence of induced straw can in the management of pre-emergent herbicides, can affect its transposition to the soil, consequently impacting on the effectiveness of weed control. Studies on the management and effectiveness of herbicides on straw are still scarce, and, to a large extent, they have been carried out on sugarcane straw. Given this, the objective of this study was to evaluate the effects of post-emergent herbicide underdoses in the corn and brachiaria intercropping, as well as to evaluate the effectiveness of diclosulam, flumioxazin and diuron + sulfentrazone in the corn straw + brachiaria and in the soil, in different rain regimes. For this, two experiments were carried out. The first experiment evaluated the effects of post - emergent herbicide underdoses in the corn and brachiaria intercropping. This study was conducted in a randomized block design, with a 3 x 8 factorial scheme, with three cultivation systems: single corn, intercropping 1 (corn + Urochloa ruziziensis) and intercropping 2 (corn + U. decumbens), and eight treatments: atrazine (1500 g a.i. ha-1); atrazine + mesotrione (1500+ 60 g a.i. ha-1); atrazine + mesotrione (1500+ 40 g a.i. ha-1); atrazine + glyphosate (1500 g a.i. ha-1 + 45 g a.i. ha-1); atrazine + glyphosate (1500 g a.i. ha-1 + 22.5 g a.i. ha-1); atrazine + nicosulfuron (1500+ 7 g a.i. ha-1); besides two witnesses (weed and not weed). The herbicides were applied at the phenological stage V6 for corn, U. ruziziensis at the stage of 5-7 tillers and U. decumbens at the stage of 4-6 tillers. The second experiment evaluated the efficacy of diclosulam, flumioxazin and diuron + sulfentrazone on stubble corn+brachiaria and soil, under different rain regimes, on the effectiveness of controlling Ipomoea hederifolia. The experimental design used was completely randomized, adopted in isolation for each of the herbicides diclosulam (35.03 g a.i. ha-1), flumioxazin (25 g ia ha-1) and diuron + sulfentrazone (diuron: 455 g ia ha-1+ sulfentrazone: 255.5 g ai ha-1). Five periods without rain were obtained after the application of the herbicides (0, 2, 5, 7 and 10 days after application), two coverings (with and without straw from the corn + brachiaria intercropping) and four layers of rain (0, 10, 20 and 30 mm). For the first experiment, nicosulfuron provided the lowest accumulation of dry biomass for the species. As underdoses of the herbicides affected the straw yield. However, the intercropping's straw production surpassed that of single cultivation. For the second experiment, diuron + sulfentrazone showed the best control in the presence of corn and brachiaria intercropping straw, in relation to the herbicides diclosulam and flumioxazin. Diuron + sulfentrazone was effective in controlling I. hederifolia, and diclosulam and flumioxazin were not effective. It was concluded that the largest increment of straw occurred in the intercropping of corn with U. ruziziensis, and that the different rain regimes and the presence of straw affected the effectiveness of diclosulam and flumioxazin. (AU) | |
| FAPESP's process: | 19/02678-0 - Dynamics of pre-emerging herbicides on corn and brachiary straws and effectiveness of control on buva and capim-amargoso in different conditions of precipitation |
| Grantee: | Nágilla Moraes Ribeiro |
| Support Opportunities: | Scholarships in Brazil - Master |