Banca de QUALIFICAÇÃO: GERLAN DO NASCIMENTO RODRIGUES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GERLAN DO NASCIMENTO RODRIGUES
DATE: 05/04/2024
TIME: 09:00
LOCAL: ON LINE
TITLE:

Herbicide selectivity and nitrogen fertilization in the cultivation of forage cactus (Nopalea cochenillifera) (L.) Salm – dick cv miúda

KEY WORDS:

cactus, xerophyte, forage plants, chemical control, mineral nutrition.

PAGES: 90
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUMMARY:

The research aimed to evaluate the effect of nitrogen fertilization and the selectivity of herbicides on the cultivation of forage palm (N. cochenillifera) cv miúda. Two experiments were set up, the first to evaluate nitrogen fertilization and the second to assess herbicide selectivity. The first experiment was conducted in a randomized complete block design, with treatments consisting of nitrogen doses (0, 25, 50, 100, 200, 400) kg ha^-1 of N and 4 repetitions, totaling 24 plots. Evaluations took place at 720 days after planting, assessing green mass (GM) and dry mass (DM) productivity of the aerial part, number of cladodes per plant (NCP) and per hectare (NCH), plant height (PH) and width (PW), cladode area index (CAI), and the economic dose of N. Data obtained were analyzed by F test and polynomial regression analysis. For herbicide selectivity assessment, the experiment was conducted in a completely randomized design in a 5 x 5 factorial scheme with four repetitions, totaling 100 experimental plots. The first factor consisted of (ixosaflutole 262.5 g.a.i/ha, flumioxazin 62.50 g.a.i/ha, imazapic 147 g.a.i/ha, sulfentrazone 400 g.a.i/ha, and a control without herbicide), and the second factor consisted of application times (0, 30, 60, 90, and 120) days after planting. The plots consisted of 20L pots with previously analyzed soil. The herbicide phytotoxicity, number of cladodes per plant (NCP), plant height (PH) and width (PW), cladode area index (CAI), photosystem II photochemical efficiency (Fv/Fm), and green mass (GM) and dry mass (DM) productivity of the aerial part and root dry mass of the forage palm were evaluated. Two assessments were carried out, at 15 and 60 days after herbicide application, except for productivity variables, which were assessed at harvest time at 300 days after planting. For the first experiment, all variables were influenced by nitrogen fertilization and showed significant quadratic response (p <0.01). The highest estimated values for GM and DM productivity, 308.84 and 31.29 t ha^-1 respectively, were associated with doses of 214.17 and 251 kg ha-1 of N, representing a productive increase of 45.32 and 67.42% compared to the treatment without fertilization. NCP and NCH showed significant quadratic response (p <0.01) to nitrogen fertilization with maximum estimated values of 48.62 and 2,035,100.43 cladodes, respectively. For PH and PW, the maximum estimated values were 95.98 and 65 cm at doses of 212 and 200 kg ha^-1 of N, respectively. CAI showed a maximum value of 3.88 m² m-2 at the dose of 221 kg ha^-1 of N, representing an increase of 55.20% when N is not used. The forage palm (N. cochenillifera) cv miúda is responsive to nitrogen fertilization, promoting significant gains in its productive and growth characteristics. For the second experiment, all variables were influenced by the herbicides. Ixosaflutole and flumioxazin caused injuries to the plants regardless of the application time, reducing plant height and width and CAI, but the plants recovered over time. The number of cladodes per plant was influenced by the herbicides at 15 DAA, and at 60 DAA, it showed a quadratic response. The productivity of green and dry mass of the palm aerial part and root productivity were not affected by the herbicides. Imazapic and sulfentrazone did not affect the productive and morphological characteristics of the forage palm, regardless of the application time. Imazapic and sulfentrazone are selective for forage palm cv miúda, while ixosaflutole and flumioxazin cause injuries to cv miúda, but the plants recover over time, therefore cannot be applied to plants with newly sprouted cladodes.

COMMITTEE MEMBERS:
Interno(a) - 3145739 - JOAO LUCIANO DE ANDRADE MELO JUNIOR
Presidente - ***.041.954-** - JORGE LUIZ XAVIER LINS CUNHA - UFAL
Externo(a) à Instituição - JOÃO GOMES DA COSTA - EMBRAPA