Leaf anatomy of 'Marandu' grass cultivated in plant arrangements in agrosilvopastoral systems

Marcia Vitoria Santos,Victor Hugo Vidal Ribeiro,Evander Alves Ferreira,Priscila Junia Rodrigues Da Cruz,Ignácio Aspiazú,Dayana Maria Teodoro Francino,Cássia Michelle Cabral,Brenda Thaís Barbalho Alencar

doi:10.1590/s0100-204x2018001200004

Abstract

Abstract: The objective of this work was to evaluate the effects of different arrangements of eucalyptus plants on the morphoanatomical characteristics of leaf blades of 'Marandu' grass [(Urochloa brizantha (Syn. Brachiaria brizantha)] plants cultivated in agrosilvopastoral systems. The experiment was set in field conditions in a randomized complete block design with four replicates, in which the plots were represented by planting spacings of eucalyptus (12x2 and 12x4 m), and the subplots, by the distance between 'Marandu' grass and eucalyptus rows (6, 4, and 2 m). A control was added, composed by 'Marandu' grass cultivated in full sun. Variables of the leaf anatomy of 'Marandu' grass were evaluated for shading interference by trees. The distance of 'Marandu' grass plants from the eucalyptus lines interfered with the leaf blade anatomy of the forage, and the highest modifications occurred in linear measures and tissue proportions in the arrangements with the highest eucalyptus density. The shading interference of eucalyptus on the anatomical characteristics of leaf blades of 'Marandu' grass depends on the adopted arrangement. This occurs due to the grass adaptation to the low-light incidence, with a consequent reduction in its physiological activity and growth.

Highlights

The treatments consisted of 'Marandu' grass, intercropped with corn and eucalyptus in an agrosilvopastoral systems, in split plots, in which the plots were represented by eucalyptus planting spacings (12x2 and 12x4 m) and, the subplots, the distance between 'Marandu' grass and eucalyptus rows (6, 4, and 2 m)
When comparing the effect of the arrangements within each spacing of 'Marandu' grass to the eucalyptus rows, there was a reduction of the DET values in the higher density arrangement (12x2 m plot, in all distances of the tree crop) (Table 2)
It is noteworthy that the DET ranged from 7.87 μm to 9.32 μm, 15.56% thinner

Summary

Introduction

In forest environments, the wide variation of the availability of incident radiation is a limiting factor to the growth of seedlings and young individuals of certain species (Valladares & Niinemets, 2008). The leaf is the primary photosynthetic organ that generally shows phenotypic plasticity in relation to light radiation, and its availability and quality can cause substantial effects on size and thickness and, on the development of the organ (Valladares & Niinemets, 2008; Sanches et al, 2009). Anatomical evaluation of plant responses to different shading levels are of great importance for the development of management systems to use agronomic, zootechnical, and arboreal species in multicrop systems, such as in agroforestry ones, known as crop-livestock-forest. The lack of knowledge on the anatomical and micromorphological changes resulting from the exposure of forage species to different levels of shading, in agrosilvopastoral systems, motivated the development of this work

Objectives

Methods

Results