Weeds under the canopies of tree species submitted to different planting densities and intercropping

Abstract

Assessing the growth and floristic composition of species that grow under the canopy of trees is important for weed control (WC). The objective of this study was to assess two experiments (E1 and E2), when the trees were two years and one year of age, respectively. In E1, sabiá (S) and gliricidia (G) were submitted to planting densities from 400 to 1.200 plants ha-1. In E2, growing systems consisting of S, G, and neem (N) combinations were compared: SSS, GGG, NNN, GSG, NSN, SGS, NGN, SNS, and GNG (each letter represents a row of plants). A random block design was adopted, with three (E1) and four (E2) replicates. In E1, treatments were arranged as split-plots (species in plots). In E2, the degrees of freedom for treatments (8) were partitioned into growing systems (treatments that involved the same species) and between growing system groups (2). Twenty-one weed species were found in E1. Gliricidia attained greater plant height than sabiá, but these species did not differ in canopy diameter, number of weed species per plot, and weed green and dry biomass of the shoot. Higher planting densities resulted in the reduction of all those traits. Twenty-six weed species were found in E2. Growing systems that included gliricidia showed canopies with greater diameters than growing systems that included neem. There were no differences between growing systems for number of weed species per plot and for weed green and dry biomass of the shoot.

Soil fertility beneath the crown of tree species submitted to planting densities

“…Souza et al (2013) found that an increase in the planting density of gliricidia and thrush reduced the growth of weeds under the crown of both species. Besides the competition between trees, and between trees and weeds, the contribution of animals to the increase in soil nutrients should not be forgotten, as discussed below.…”

Changes in plant species diversity as affected by shading conditions and continuous agricultural practices in kiwifruit orchards

“…However, covering kiwifruit orchards with nets causes artificial shading conditions since photosynthetically active radiation (PAR) is cumulatively intercepted both by the anti-hail nets and the kiwifruit canopy, with a substantial impact on plant species diversity. After all, the light competition is one of the most important factors which limits the plant species growth under the canopy of tree cultivation (Souza et al, 2013).…”