Banca de DEFESA: SAMIA RAYARA DE SOUSA RIBEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : SAMIA RAYARA DE SOUSA RIBEIRO
DATA : 24/01/2018
HORA: 09:00
LOCAL: Sala de Aula do PGEAAmb
TÍTULO:

Residual effect of herbicides applied in pre-emergence on soybean cultivation on maize and cotton grown in succession

PALAVRAS-CHAVES:

Zea mays, Gossypium hirsutum L., persistence, carryover

PÁGINAS: 99
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitotecnia
ESPECIALIDADE: Matologia
RESUMO:

The importance of soybean (Glycine max (L.) Merrill) to the country is undeniable, being the largest cultivated area in Brazil and a major source of foreign exchange through the export of grains and derivatives. The succession of crops is widely used in Brazil, taking advantage of the tropical conditions of the country, which allows successive crops with high yields of productivity. Two crops stand out in the national scenario as options of cultivation in succession to the soybean: the corn and the cotton. The search for economy and productivity is opposed to weed interference, where management tends to increase production costs, reducing profit margins and decreasing product quality. In this context, herbicides appeared as a tool to control weeds and among the types of herbicides used, the pre-emergent ones have important characteristics, among them the long residual period. However, when the bioactivity of the herbicide exceeds the cycle of the target crop, persisting in the soil by the harvest of the next crop, the so-called carryover phenomenon occurs. Given the importance of succession/rotation of crops to the country's economy and the need for rational use of herbicides, studies are necessary to understand the behavior of herbicides in soil and plants to avoid potential risk of phytotoxicity caused by the carryover. In order to evaluate the residual effect of these herbicides on the main soybean succession crops, three simultaneous experiments were conducted in the Federal Rural University of Rio de Janeiro - Seropédica/RJ, during the period from September 2016 to March 2017, in a crop succession scheme, with a randomized complete block design, with four replications per treatment. The treatments were the doses (D) of the herbicides chlorimuron-ethyl, diclosulam, flumioxazin, imazapyr + imazapique and metribuzim (0, ½D, D, ½+D and 2D) for each trial: maize, cotton and watermelon. The analyzed variables were chlorophyll a fluorescence; plant height, root length, root volume, dry shoot mass, root dry mass and antioxidant enzyme activity. The data generated in the experiment were submitted to analysis of variance (p≤0.05) and submitted to the Tukey test, at 5% probability. The choice of models was based on statistical significance (F test), on the coefficient of determination (R2) and on the biological significance of the model. Maize was slightly affected by the residual chlorimuron, diclosulam, flumioxazin, imazapyr + imazapic and metribuzim applied in pre-emergence in the soybean crop, demonstrating that maize has a relative tolerance to these pre-emergence herbicides within 100 days. Cotton was more sensitive to chlorimuron-ethyl herbicides and the formulated mixture of imazapyr + imazapic. For the other herbicides, no changes were observed in cotton growth and development. The watermelon was more sensitive to chlorimuron and imazapyr + imazapic, which shows a greater residual of these herbicides in the soil. For maize and cotton crops, the formulated mixture of the herbicides imazapir + imazapic caused more severe phytotoxic effects in the early vegetative stages of the plants, indicating that this is a critical period in the crop and requires greater attention to the management of this herbicide in the pre- emergency. The GST enzyme is more sensitive to the presence of the herbicides chlorimuron-ethyl, diclosulam, flumioxazin, imazapyr + imazapic and metribuzim.

MEMBROS DA BANCA:
Presidente - 2466219 - CAMILA FERREIRA DE PINHO
Interno - 829.025.000-25 - CLAUDIA DE OLVEIRA - UFRRJ
Externo à Instituição - JUNIOR BORELLA - UFRRJ
Externo à Instituição - CRISTINA MOLL HUTHER - UFF