Competição de gramíneas com Khaya ivorensis A. Chev, em crescimento inicial: aspectos fisiológicos e nutricionais

• Ano de defesa: 2024
• Autor(a) principal: Yuri Silva Saraiva Guimarães
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ICA - INSTITUTO DE CIÊNCIAS AGRÁRIAS; Programa de Pós-Graduação em Ciências Florestais; UFMG
• Palavras-chave em Português: Mogno; Nutrientes; Fisiologia
• Link de acesso: http://hdl.handle.net/1843/68101; https://orcid.org/0000-0001-5728-2692

Khaya ivorensis A. Chev. Is a species of interest for forestry in Brazil, due to its great economic potential. However, there is little information about the presence of grasses and their competition on K. ivorensis seedlings. Therefore, this study aims to evaluate the competitive aspects of grasses on K. ivorensis seedlings. The experiment was conducted in randomized blocks, consisting of 6 treatments and 8 replications, with each experimental plot composed of a pot containing a K. ivorensis seedling in coexistence or not with an individual weed. The treatments were: control, composed of only one K. ivorensis seedling; K. ivorensis + Urochloa decumbens; K. ivorensis + Megathyrsus maximus; K. ivorensis + Sorghum arundinaceum; K. ivorensis + Digitaria insularis and K. ivorensis + Cynodon dactylon. At 0 and 105 days after transplanting, height and diameter measurements of K. ivorensis seedlings were taken. At 90 days after transplanting, analyzes of chlorophyll a, chlorophyll b, photosynthetic rate, stomatal conductance, transpiration, and calculation of water use efficiency were performed. At 105 days after transplanting, K. ivorensis plants were collected to determine the dry matter of the shoot and root and determine the specific leaf area. Also at 105 days after transplanting, samples of the aerial and root parts of K. ivorensis were removed, dried in an oven and ground to determine the levels of N, P, K, Ca and Mg. The content, relative content, biological utilization coefficient (CUB), efficiency of use of macronutrients in the shoot and root and efficiency of absorption by the plant (EA) were also determined. K. ivorensis seedlings in coexistence with U. decumbens, M. maximus and S. arundinaceum showed smaller increases in height and diameter. The presence of competitors M. maximus and S. arundinaceum resulted in a smaller leaf area in K. ivorensis seedlings. The dry matter of the aerial part of K. ivorensis was reduced when coexisting with S. arundinaceum. On the other hand, the coexistence of C. dactylon with K. ivorensis did not affect the growth variables of the tree species. K. ivorensis seedlings in coexistence with U. decumbens, M. maximus and S. arundinaceum showed lower chlorophyll a and b values. Coexistence with the tested weeds decreased the photosynthetic rate and water use efficiency of K. ivorensis seedlings. The presence of U. decumbens, M. maximus and S. arundinaceum reduced the relative content of nutrients evaluated in K. ivorensis. Coexistence with U. decumbens, M. maximus and S. arundinaceum reduced the N, K and Mg content of K. ivorensis. The CUB and EA in K. ivorensis were also affected by coexistence with weeds. Therefore, coexistence with the evaluated grasses negatively affects the growth, chlorophyll a and chlorophyll b contents, photosynthetic rate, and water use efficiency of K. ivorensis seedlings. The presence of grasses negatively affects nutrient content, content, relative content, CUB and EA in K. ivorensis seedlings. Megathyrsus maximus was more harmful to the growth and physiology of K. ivorensis than the other grasses studied.