Do exclosure cages affect canopy microenvironment, morphogenetic responses and morphophysiological characteristics on pastures under continuous stocking?

• Grant number: 17/11288-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2018
• End date: February 29, 2020
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Pastures and Forage Crops
• Principal Investigator: Carlos Guilherme Silveira Pedreira
• Grantee: Júnior Issamu Yasuoka
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The use of exclosure cages is well-stablished as an experimental technique to estimate forage accumulation on pastures under continuous stocking. Errors in such estimate, however, can occur due to morphophysiological and microclimate changes in the vegetation within the cages in comparison to areas not excluded from grazing. These changes depend on the canopy condition at the time of exclusion. The magnitude of these modifications also depends on the extent of the exclusion period. For these reasons, many authors argue that the forage accumulation measured within cages can be greater or lesser than the accumulation outside, athough there are no reports in the literature that document whether these modifications really occur. The objective of this study is to describe and explain the effects of exclosure cages on structural and morphogenetic characteristics, photosynthesis, and microclimate of Mulato II brachiariagrass canopies kept at 20 and 30 cm heights by mimicked continuous stocking with variable stocking rate and three exclusion periods. The trial will be carried out at Escola Superior de Agricultura "Luiz de Queiroz", USP, in Piracicaba-SP during two summer grazing seasons. The experimental design will be a split-plot randomized complete block, with two canopy height (20 and 30 cm) as the plots, and three exclusion periods (14, 21, and 28 d) as the subplots, with three replications, totalling 6 experimental units. The response variables studied will include forage accumulation, leaf area index, light interceptation, mean foliage angle, light extinction coefficient, leaf and canopy photosynthesis rates, morphogenetic responses, and microclimate. Data will be analyzed using Proc Mixed of SAS and the means will be compared by Student's t test with the level of significance set at 5%. Microclimate variables will be correlated with morphophysiological and morphogenetic variables to help the explanation of results. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

YASUOKA, JUNIOR I.; PEDREIRA, CARLOS G. S.; HOLSCHUCH, SOLANGE G.; ALMEIDA, OTAVIO G.; PEDROSO, GABRIEL B.. The exclosure cage technique revisited: Pasture responses under continuous stocking and their relationship with estimates of forage accumulation in grazing experiments. CROP SCIENCE, v. 61, n. 2, FEB 2021. (17/11288-6)

YASUOKA, JUNIOR ISSAMU; SILVEIRA PEDREIRA, CARLOS GUILHERME; HOLCMAN, ESTER; SENTELHAS, PAULO CESAR; PEDROSO, GABRIEL BARACAT; DE ALMEIDA, OTAVIO GOULART; HOLSCHUCH, SOLANGE GARCIA. Microclimate of grass canopies and biomass accumulation are influenced by the use of caged exclosures in grazing research. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY, v. 66, n. 1, SEP 2021. (17/11288-6)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

YASUOKA, Júnior Issamu. Agronomic and microclimatic responses inside exclosure cages and their impacts on forage accumulation estimate on pastures under continuous stocking. 2020. Doctoral Thesis - Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) Piracicaba.