Grass Weeds Interfering with Eucalypt: Effects of the Distance of Coexistence on the Initial Plant Growth

Abstract

-Two experiments were carried out to evaluate the initial plant growth of Eucalyptus urograndis growing in coexistence with Urochloa decumbens and U. ruziziensis. In 100-L box, one plant of U. decumbens or U. ruziziensis grew in coexistence with one plant of E. urograndis clones C219H or H15, respectively, in the distances of 0, 5, 10, 15, 20, 25, 30, 35, and 40 cm from the crop. After 30, 60, 90 (both clones), and 150 days (just for H15), growth characteristics were evaluated. Plants of both clones, growing in weed-free situations, showed a better growth and development than plants that grew in weedy situations, independently of the distance, having the highest plant height, stem diameter, dry mass of stem, and dry mass of leaves. As the same way, the number of branches, number of leaves, and leaf area of the clone C219H were similarly affected. Urochloa ruziziensis reduced the dry mass accumulation of stem and leaves by the rate of 0.06 and 0.32 g per plant, respectively, per each centimeter growing nearest to the crop, while U. decumbens reduced by 0.03 and 0.14 g per plant. The interference of U. decumbens and U. ruziziensis with E. urograndis is more intense when weedy plants grow in short distances from the crop. 0, 5, 10, 15, 20, 25, 30, 35 Keywords: Eucalyptus urograndis, Urochloa decumbens, Urochloa ruziziensis, weed competition. RESUMO -Dois experimentos foram realizados para avaliar o crescimento inicial das plantas de Eucalyptus urograndis crescendo em convivência com Urochloa decumbens e U. ruziziensis. Em vasos de concreto de 100 L, uma planta de U. decumbens ou U. ruziziensis cresceu em coexistência com uma planta de E. urograndis, dos clones C219H ou H15, respectivamente, nas distâncias de

Can Allelopathic Grasses Limit Seed Germination and Seedling Growth of Mutambo? A Test with Two Species of Brachiaria Grasses

“…The genus characteristics, as sexual and vegetative reproduction, rapid reproductive cycle, high photosynthetic and nutrient use efficiency and high growth rates (Oliveira et al, 2006;Pires et al, 2012) make it highly competitive with native species. Furthermore, recent studies have demonstrated the allelopathic activity of the genus in different plant species (Barbosa et al, 2008;Contreiras-Rodrigues et al, 2012;Kato-Noguchi et al, 2014;Graat et al, 2015). Thus, studies that evaluate the influence of Urochloa genus on the establishment of tree species are important to provide information that supports the re-introduction of these in abandoned pastures.…”

Interference of Urochloa decumbens and Panicum maximum in the initial growth of six clones of Eucalyptus urograndis

“…Silva et al (1997) observed that Corymbia citriodora (ex E. citriodora) was more sensitive to competition with Brachiaria brizantha than E. grandis. Different responses for different E. urograndis clones have also been reported (Cruz et al, 2010;Graat et al, 2015).…”

“…Since the clones have different response to weed interference during early growth (Cruz et al, 2010;Pereira et al, 2013;Graat et al, 2015), evaluate the performance of previously existing and promising clones of E. urograndis, during early growth, and with interference by U. decumbens and P. maximum, may provide information and support for genetic improvement programs. In this way, we aim to evaluate the interference of U. decumbens and P. maximum on the early development of six clones of E. urograndis (E. urophylla x E. grandis) as well as the reciprocal effect.…”

Herbicides for weed control in eucalypt

“…Crown diameters about 2 m provided favorable conditions for initial growth of eucalypt seedlings. Graat et al (2015) evaluated coexistence effects between one Urochloa decumbens or U. ruziziensis positioned at distances (0 to 40 cm) from one Eucalyptus urograndis plant (C219H or H15 clones). Plants grown free of weeds showed higher height, stem diameter, stem dry mass and leaves dry mass than plants grown in coexistence.…”

“…According to Hakamada et al (2010) weed interference can cause losses of up to 50 % in eucalypt yield and reduction of over 90 % in the profitability of forestry enterprise. About 30 % of total production cost and up to 50 % of manpower used in eucalypt cycle is intended for weed control.…”