Morphogenetic and structural characteristics of tillers of guinea grass of different age and grazing severities

Marciele Neves Carloto,Valéria Pacheco Batista Euclides,Hélio Henrique Vilela,Domicio Do Nascimento Júnior,Braulio Maia De Lana Sousa,Sila Carneiro Da Silva,Denise Baptaglin Montagner,André Fischer Sbrissia

doi:10.1590/s1516-35982011001000006

Abstract

The objective of this research was to evaluate the effects of tiller age on morphogenic and structural characteristics of guinea grass cv. Mombaca subjected to intermittent stocking and three stubble heights: 30 cm, 50 cm and 50-30 cm. Stubble heights were assigned to experimental units in a completely randomized block design with three replicates. Grazing was performed when canopy intercepted 95% of light incidence. Leaf appearance rate, leaf elongation rate and number of live leaves per tiller were higher in the summer when compared with the winter. Contrarily, stem elongation rate, phyllochron and leaf lifespan were lower in the summer when compared with the winter. During the summer, young tillers had higher leaf appearance and elongation rates when compared with the older ones. Young and mature tillers had the highest values of live leaves per tiller in the summer. There was no difference between summer and winter for the final length of leaf blade between tillers of the same age, except in mature tillers, which had higher final leaf length during the summer. Senescence rate of leaves was higher in young tillers, followed by mature and old tillers. Age of tiller affects morphogenic and structural characteristics of pasture, showing that young tillers have better growth compared with mature and old tillers

Highlights

Pastures are comprised of plant population, and each plant is formed by basic units called tillers, as in the case of forage grasses (Valentine and Matthew, 1999)
The study of morphogenic and structural characteristics has contributed to the understanding of the process of biomass accumulation under a grazing system
The condition of 95% of light interception was reached at 93 cm of sward height, regardless of the season of the year

Summary

Introduction

Pastures are comprised of plant population, and each plant is formed by basic units called tillers, as in the case of forage grasses (Valentine and Matthew, 1999). Forage accumulation in pastures results from the total of all the units which compose it (Matthew et al, 2001). The study of morphogenic and structural characteristics has contributed to the understanding of the process of biomass accumulation under a grazing system. This knowledge enables the management of pasture conditions such as frequency and severity of defoliation (Da Silva et al, 2009; Pena et al, 2009). Recent research (Carnevalli et al, 2006; Barbosa et al, 2007; Giacomini et al, 2009a,b; Mesquita et al, 2010) indicates that the optimal time for regrowth coincides with interruption at interception of 95% of incident light by the canopy

Objectives

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Results