Banca de DEFESA: ELISVALDO JOSÉ SILVA ALENCAR

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ELISVALDO JOSÉ SILVA ALENCAR
DATE: 10/08/2022
TIME: 13:30
LOCAL: Departamento de Zootecnia
TITLE:

MORPHOLOGY AND PRODUCTION OF Cenchrus Purpureus (Schumach.) Morrone GENOTYPES WITH DIFFERENT SIZES UNDER TWO HARVEST FREQUENCIES

KEY WORDS:

Elephantgrass, Cutting Age, Morphology, DM Production

PAGES: 72
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Pastagem e Forragicultura
SPECIALTY: Manejo e Conservação de Pastagens
SUMMARY:

The characterization and selection of more productive elephant grass genotypes, attributed to the age of harvest, can contribute to supply part of the forage demand for the herd throughout the year. In this sense, the objective was to evaluate the effect of harvest frequency (60 and 90 days) on structural, morphogenic and productive characteristics of Cenchrus purpureus (Schumach.) Morrone genotypes of different sizes. The research was conducted at the Experimental Farm of UFRPE, Garanhuns-PE. The experimental treatments consisted of four genotypes of Cenchrus purpureus, two tall (IRI 381 and Elephant B) and two dwarfs (Taiwan A-146 2.37 and Mott), associated with two harvest frequencies (60 and 90 days) under irrigation. The experimental design was randomized blocks, in a split-plot scheme and four replications. The evaluations were carried out on marked tillers in each plot, in a delimited area of 0.5 m², every 15 days until the genotypes harvest period (60 and 90 days) during the rainy and dry seasons. Leaf appearance rate, leaf and stem elongation rate and phyllochron, plant height, stem diameter, leaf blade and stem length, tiller population density and number of leaves were studied. The growth indices were also evaluated: absolute growth rate and relative growth rate, leaf area index and light interception. The productive characteristics evaluated were forage production per cut, leaf production per cut, stalk production per cut, annual forage production, annual leaf production, annual stalk production, and leaf/stem ratio. of leaf elongation, differing from the other evaluated genotypes, in the two harvest ages. For the stem elongation rate, it was observed that during the rainy season the tall genotypes did not differ from each other and showed a higher rate of stem elongation, compared to the short ones. For phyllochron, tall genotypes showed lower phyllochron in the rainy season. The plant height of tall genotypes is 40 to 60% greater than that of dwarf genotypes. The population density of basal tillers of Taiwan A-146 2.37 is 30 to 37% higher compared to the other genotypes in both harvest frequencies. The stem diameter of the genotypes evaluated in the rainy season was higher for Elephant B and lower for Taiwan A-146 2.37. During the dry season, the stem elongation of the Taiwan A-146 2.37 genotypes occurred more slowly when compared to the rainy season. With 60 days of harvest, the tall genotypes had the highest absolute growth rates (0.045 and 0.047 cm.day^-1). In the dry season, it was found that at 60 days the absolute growth rate was higher (2.85 cm.day^-1). As for the growth rate relative to the rainy season, there was no difference between harvest frequencies. In the dry season, the harvest frequency of 60 days showed the highest relative growth rate (0.045 cm.cm ^-1.day^-1). Mott and Elephant B had the highest light interception with 93 and 90%, respectively. The highest forage and stem production was observed in tall genotypes, at the 90-day harvest frequency (8869.4 and 5950.2 kg of DM ha^-1.cut^-1, respectively). The frequencies of harvests had a marked effect on the morphogenic and structural characteristics of the Cenchrus purpureus genotypes, such as a shorter interval between the appearance of two leaves between the times, better tillering at 60 days of harvest. It is recommended to use a harvest frequency of 60 days in the dry season due to the higher density of tillers, larger leaves and shorter leaf appearance intervals, seeking better quality forage. Under irrigation, in areas where there are lower temperatures in the rainy season, it is recommended to use a harvest frequency of 60 days for the high (Elefante B and IRI 381) and low (Mott and Taiwan A-146 2.37) genotypes at the time. drought, aiming at higher annual leaf production and higher leaf/stem ratio in the harvested forage.

BANKING MEMBERS:
Presidente - 385004 - MERCIA VIRGINIA FERREIRA DOS SANTOS
Interno - 2346742 - ALEXANDRE CARNEIRO LEAO DE MELLO
Interno - 3514546 - MARCIO VIEIRA DA CUNHA
Externo ao Programa - 384136 - RINALDO LUIZ CARACIOLO FERREIRA - UFRPEExterna à Instituição - MARIA DA CONCEICAO SILVA - IPA