Banca de DEFESA: WÉLLEN SÂNGELA MENDES BEZERRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : WÉLLEN SÂNGELA MENDES BEZERRA
DATA : 04/04/2022
HORA: 08:30
LOCAL: Embrapa
TÍTULO:

AGROMETEOROLOGICAL MODEL FOR PRODUCTIVITY PREDICTION OF ZURI GRASS UNDER CONTRASTING NUTRITIONAL MANAGEMENTS

PALAVRAS-CHAVES:

Fertilization management; forage accumulation; photosynthetic radiation.

PÁGINAS: 43
GRANDE ÁREA: Ciências Agrárias
ÁREA: Zootecnia
SUBÁREA: Pastagem e Forragicultura
ESPECIALIDADE: Avaliação, Produção e Conservação de Forragens
RESUMO:

Facing the great production potential of tropical forages, Brazil has been gaining notoriety on a world scale with cattle ranching on pasture. This is because when these forages are subjected to good management, the animals' diet can reach nutritional value that allows considerable gains in productivity. The objective of this work was to validate an agrometeorological model based on interannual and seasonal variability of climate and dry mater yield (DMY) of zurigrass (Panicum maximum 'BRS Zuri' syn. Megathirsus maximus) under different nutritional managements. In 2017, the trial was implemented at the experimental field of Embrapa Rondônia in the municipality of Porto Velho. Data from 19 cycles/cuts were collected from February 2018 to December 2019. The experimental design was in randomized split-block with measurements repeated in time. The nutritional management was classified according to the annual nitrogen (N) dose as: low (100 kg of N.ha^-1.year^-1), medium (250 kg of N.ha^-1.year^-1) and high (500 kg of N.ha^-1.year^-1). The potassium fertilization followed the recommendation of 80% of the N dose. For the model parameterization and validation, the climatic data were taken from two meteorological stations located in the city of Porto Velho. The photosynthetically active radiation intercepted (PARi) and leaf area index (LAI) were measured with an AccuPAR LP-80 ceptometer. Dry matter (DM) production was higher in cycles 6, 7 and 8 in 2018 and in cycles 11, 12, 13, 18 and 19 in 2019. The DMY was higher in high nutritional management with average of 2,941.07 Kg DM.ha^-1. The average light extinction coefficient observed in grass under the three nutritional managements was -0.76. The model parameters that indicate the linear relationship between the Accumulated Degree-Day (GDA, °C) and the LAI were 0.0061, 0.0045 and 0.003 for the high, medium and low nutritional managements, respectively. The means of radiation use efficiency (RUE) had values of 2.08, 1.79 and 1.45 for the high, medium and low managements, respectively. Zuri-grass has better rates of PARi, LAI and higher productivity (1,993.93 kg DM.ha^-1) in the period without water restriction and when submitted to the nutritional management of 500 kg of N.ha^-1.year^-1 and 400 kg of KCl.ha^-1.year^-1. The agrometeorological model is able to estimate the productivity of zuri-grass in different fertilizations with or without water restriction.

MEMBROS DA BANCA:
Presidente - 162.237.228-00 - ANA KARINA DIAS SALMAN - EMBRAPA
Interno - 958.305.370-87 - LUIZ FRANCISCO MACHADO PFEIFER - EMBRAPA
Interno - 1545801 - JAIRO ANDRE SCHLINDWEIN
Externo à Instituição - ODILENE DE SOUZA TEIXEIRA - UNIR