Forage mass and structure of piatã grass deferred at different heights and variable periods

Hélio Henrique Vilela,Camila Zimmer De Assis,Manoel Eduardo Rozalino Santos,Gabriel De Oliveira Rocha,Domicio Do Nascimento Júnior,Andreza Luzia Santos,Braulio Maia De Lana Sousa,Bruno Damaceno Faria

doi:10.1590/s1516-35982012000700010

Hélio Henrique Vilela, Camila Zimmer De Assis + Show 6 more

Open Access

https://doi.org/10.1590/s1516-35982012000700010

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Abstract

The objective of this study was to determine the deferment period and the most adequate initial sward height of Brachiaria brizantha cv. Piata for deferment in the region of Vicosa, Minas Gerais. For so, the following characteristics were evaluated: masses and bulk density of forage and its morphological components, light interception by the sward, leaf area index, leaf angle, sward and extended tiller height and falling index of the deferred piata grass. The three deferment periods assessed (65, 85 and 105 days) were randomized to the plots and the three sward heights (20, 30 and 40 cm), randomized in the subplots. The experimental design was of completely randomized blocks, with three replicates, in a subdivided plots arrangement. Masses of forage, green stem and dead tissue were higher in the piata grass managed with deferment period of 105 days. The mass of green leaf blade was higher in the piata grass deferred with 20 cm height associated to the deferment period of 85 days, which had, as consequence, greater bulk density of green leaf blade. The interception of light by the sward was greater in the piata grass kept longer in deferment associated with the higher leaf area index, regardless of its initial height. The heights of the sward and extended tillers were greater in the piata grass under periods of 85 and 105 days of deferment; however, the falling index was not affected by the factors studied. In the region of Vicosa, Minas Gerais, B. brizantha cv. Piata fertilized with 75 kg/ha nitrogen and deferred with initial height of 20 cm and for a period of 85 days, from mid April, has adequate productivity and structure for animal production.

Highlights

In most of Brazil, especially due to reduction in the temperature and water availability, there is decrease or interruption of forage plant growth during the months of winter, which results in forage shortage in the production system
Piatã fertilized with 75 kg/ha nitrogen and deferred with initial height of 20 cm and for a period of 85 days, from mid April, has adequate productivity and structure for animal production
There was no effect of initial height on the interception of light by the piatã grass subjected to deferment period of 105 days (Table 2)

Summary

Introduction

In most of Brazil, especially due to reduction in the temperature and water availability, there is decrease or interruption of forage plant growth during the months of winter, which results in forage shortage in the production system. The initial height of the pasture in the beginning of deferment influences its leaf area, which has a direct connection to the plant capacity of intercepting light radiation, which is one of the basic premises for maintenance of photosynthesis at its maximum level (Parsons et al, 1983). This way, the initial deferment height affects pasture growth rate, which, in turn, modifies the morphological and structure differentiation of the pasture

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