Aluminum tolerance on genotypes of signal grass

Abstract

-The objective of this work was to evaluate aluminum tolerance of five genotypes of Urochloa decumbens (D24, CD24-2, CD24-27, CD24-45 e D62) and five genotypes of Urochloa ruziziensis (R30, R44, R46, R50 and R125) in hydroponic system. Uniform tillers were collected from these genotypes and transferred to two solutions: solution 1 (200 μM CaCl 2 , pH 4.2) and solution 2 (200 μM CaCl 2 + 200 μM AlCl 3 , pH 4.2). Twenty-one days later, the roots of the plants were separated, stained and digitalized for analysis of the length and diameter of the main root. The experiment was conducted in a completely randomized design, in factorial (genotypes × doses) with three replications. A significant interaction occurred between genotype and dose for length and width of the main root, and the results presented in average, a significant difference for most genotypes. The means of main root length in the absence and presence of aluminum were not significant for D62 (U. decumbens cv. Basilisk), CD24-45 and R46. Means were not significant for the diameter of the main root for CD24-2, CD24-27 and D62. Genotype D62 was the only one classified as tolerant to aluminum and R50 the only one classified as sensitive. Most evaluated genotypes showed medium to low tolerance. This classification was based on confidence intervals (IC 99%) for the mean of the relative tolerance indices estimated for length and diameter of the main root. These results can be used in the choice of progenitors aiming at developing segregating populations for studies of inheritance and mapping of genes and/or loci related to aluminum tolerance in Urochloa.Key Words: abiotic stresses, acid soils, forages, Urochloa decumbens, Urochloa ruziziensis Tolerância ao alumínio em genótipos de capim-braquiária RESUMO -O objetivo neste trabalho foi avaliar a tolerância ao alumínio de cinco genótipos de Urochloa decumbens (D24, CD24-2, CD24-27, CD24-45 e D62) e cinco de Urochloa ruziziensis (R30, R44, R46, R50 e R125) em cultivo hidropônico. Desses genótipos, foram coletados perfilhos uniformes que foram transferidos para duas soluções: solução 1 (200 μM CaCl 2 , pH 4,2) e solução 2 (200 μM CaCl 2 + 200 μM AlCl 3 , pH 4,2). Após 21 dias, as plantas tiveram suas raízes separadas, coradas e digitalizadas para análise do comprimento da raiz principal e do diâmetro da raiz principal. O experimento foi realizado em delineamento inteiramente casualizado, em fatorial (genótipos × doses) com três repetições. Houve interação significativa entre genótipo e dose para comprimento e diâmetro da raiz principal, cujos resultados apresentaram, na média, diferença significativa para a maioria dos genótipos. As médias de comprimento da raiz principal na ausência e na presença de alumínio não foram significativas para D62 (Urochloa decumbens cv. Basilisk), CD24-45 e R46. Para diâmetro da raiz principal, as médias não foram significativas para CD24-2, CD24-27 e D62. O genótipo D62 foi o único classificado como tolerante ao alumínio e o R50, o único sensível. A maior parte dos genótipos ...

Evaluation of aluminum resistance in hybrids of Brachiaria decumbens Stapf.

“…The sexual parent D24/27, despite being a duplicated B. decumbens accession, showed much less resistance to Al when compared to the male apomictic parent. Bitencourt et al (2011) evaluated these parents in nutritive solution and did not observe significant differences for main root length between the two solutions (with and without Al) for Basilisk, whereas for D24/27, this difference was significant, corroborating the results of this experiment. This difference was also observed in the field, in a distroferric soil, where these parents were evaluated for agronomic traits, and cv.…”

“…that there is genetic variability within and between species for this trait (Bitencourt et al 2011). Thus, the objective of this study was twofold: to evaluate intraspecific hybrids of B. decumbens for edaphic adaptation, determining root vigor and aluminum resistance; and to study the inheritance of this trait in order to verify if the progeny maintains the level of adaptation already present in the commercial cultivar (B. decumbens cv.…”

Tamanho de parcela e efeito de bordadura no melhoramento de Urochloa ruziziensis

“…B. ruziziensis) é uma exceção, sendo a única cultivada no Brasil com reprodução sexual e diploide . Essa espécie apresenta genótipos com resistência ao alumínio (Bitencourt et al, 2011;Martins et al, 2011), resistência à cigarrinha-das-pastagens (Souza Sobrinho et al, 2010a) e com boa qualidade nutricional (Lopes et al, 2010). Assim, essa espécie é uma gramínea importante em programas de melhoramento de pastagens, pois, além do melhoramento intraespecífico, possibilita a obtenção de híbridos interespecíficos via duplicação cromossômica de plantas.…”

Early Seedling Growth as a Tool to Assess the Tolerance of Urochloa brizantha Cultivars to Free Aluminium

“…According to Bitencourt et al (2011), Ramos et al (2012, and Arroyave et al (2011;2013), the Basilisk cultivar is the most resistant to poor soils and to free aluminium. Based on the dendrogram made using the phenotypic characters for both assays, it could be seen that the Basilisk cultivar was the most distant cultivar in both dendrograms (Figure 7).…”