Bruna Rafaela da Silva Menezes

Genetic diversity of elephant grass (Cenchrus purpureus [Schumach.] Morrone) for energetic production based on quantitative and multi-category traits

CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 76(1) JANUARY-MARCH 2016 7 7 Elephant grass (Cenchrus purpureus (Schumach.) Morrone) has been used as an alternative source of energy. It is widely cultivated in Brazil, however it needs genotypes adapted to different ecosystems of the country. The knowledge of genetic diversity allows the identification of genotypes that can be used in breeding programs. Thus, this study aimed to evaluate the diversity among 85 genotypes of elephant grass by Tocher’s clustering method and by the unweighted pair group method with arithmetic averages (UPGMA), using quantitative and multi-category traits in 2 yr of evaluations. The experiment was implemented in the State Center for Research on Bioenergy and Waste Use at Pesagro-Rio, located in Campos dos Goytacazes, Río de Janeiro, Brazil. Eighty-five elephant grass genotypes donated by the Active Elephant Grass Germplasm Bank of Embrapa Dairy Cattle, in Coronel Pacheco, Minas Gerais, Brazil, were included in the experiment. The experimental design was arranged as randomized blocks, with two replicates. Based on the quantitative traits, the 85 genotypes analyzed belonged to 17 groups according to Tocher’s optimization method and to 13 groups when analyzed by UPGMA. For the qualitative traits, however, the genotypes formed 10 groups for both methods. Therefore, the multivariate technique indicated genetic divergences among the genotypes and allowed the formation of similarity groups by Tocher’s optimization and UPGMA methods for both the quantitative and qualitative traits.

Canonical correlations among morpho-agronomic and chemical traits in hybrids between elephant grass and millet

Studies involving the canonical correlation analysis in forage plants for interspecific hybrids between elephant grass (Pennisetum purpureum) and millet (Pennisetum glaucum) are scarce. The objectives of this study were to obtain estimates of coefficients of phenotypic, genotypic, and residual correlation and evaluate the degree of association between morpho-agronomic and chemical traits in 132 interspecific hybrids between elephant grass and millet. The experiment was conducted in the city of Coronel PachecoMG (Brazil). The experimental design was randomized complete blocks with 132 treatments and three replicates. Morphoagronomic and bromatological characteristics were analyzed. The correlation analysis indicated that plants with elevated dry matter yield considering the whole plant, leaf or stem in taller plants and plants with intense tillering have lower crude protein contents, while plants with a greater diameter show lower percentages of fiber and cellulose and greater dry matter digestibility in vitro. By canonical correlations, the chi-squared test at 1% probability by was found that the hybrids showing morpho-agronomic and chemical patterns with taller plants and high dry stem matter yield have increased percentage of cellulose. In contrast, in the same canonical pair, plants with reduced leaf dry matter yield showed lower contents of silica and organic matter and reduced digestibility in vitro. The effect on the improvement of forage quality in hybrids of Pennisetum and millet was evidenced by the better performance of the plants for high dry matter yield of the stem, showing the potential of the same for inclusion in breeding programs.

Prediction of genetic gains by selection indices using mixed models in elephant grass for energy purposes

Genetically improved cultivars of elephant grass need to be adapted to different ecosystems with a faster growth speed and lower seasonality of biomass production over the year. This study aimed to use selection indices using mixed models (REML/BLUP) for selecting families and progenies within full-sib families of elephant grass (Pennisetum purpureum) for biomass production. One hundred and twenty full-sib progenies were assessed from 2014 to 2015 in a randomized block design with three replications. During this period, the traits dry matter production, the number of tillers, plant height, stem diameter, and neutral detergent fiber were assessed. Families 3 and 1 were the best classified, being the most indicated for selection effect. Progenies 40, 45, 46, and 49 got the first positions in the three indices assessed in the first cut. The gain for individual 40 was 161.76% using Mulamba and Mock index. The use of selection indices using mixed models is advantageous in elephant grass since they provide high gains with the selection, which are distributed among all the assessed traits in the most appropriate situation to breeding programs.

DIFFERENT STABILITY METHODS FOR CULTIVAR RECOMMENDATION IN ELEPHANT-GRASS FOR ENERGY PURPOSES IN BRAZIL

The elephant-grass undergoes successive cutting and periodical evaluations that it possible to identify clones with high stability for dry matter production, which can be used for energy production. The present study was carried out to evaluate stability dry matter yield for different parametric and non-parametric methods in elephant grass genotypes for biomass production undergoes successive cutting in the agroclimatic conditions of the Norte Fluminense (RJ, Brazil). The variable measured in the 40 genotypes was dry matter yield (DMY) at 2009, 2010 and 2011 in a field study designed as randomized block design with two replicates. Each sample was grown in different environment condition. The stability methods tested were the Yates and Cochran’s, Plaisted and Peterson’s, Wricke’s ecovalence, Annicchiarico’s, Lin and Binns’ and Kang and Phan’s. Results indicated that cutting (E) and genotypes (G) influenced significantly on the performance of dry matter yield. The non-parametric stability methods were effective for the evaluation of stability in dry matter yield. Genotypes Mercker, Pinda-México, Mercker 86-México, Guaçu/IZ, Mercker Pinda, P-241-Piracicaba and Cubano Pinda were stable stability dry matter yield. Hence, there are genotypes may be exploited in future breeding programmes in order to improve productivity of upland elephant grass over environment. MÉTODOS DE ESTABILIDADE DIFERENTES PARA RECOMENDAÇÃO DE CULTIVAR EM CAPIM ELEFANTE PARA FINS DE ENERGIA NO BRASIL RESUMO: O capim-elefante sofre sucessivos cortes em avaliações periódicas, possibilitando identificar clones com alta estabilidade para a produção de matéria seca, podendo ser utilizados para a produção de energia. O presente estudo foi realizado para avaliar a estabilidade na produção de matéria seca, considerando métodos paramétricos e não paramétricos, em genótipos de capim-elefante para produção de biomassa submetido a cortes sucessivos nas condições climáticas do Norte Fluminense (RJ, Brasil). A variável medida nos 40 genótipos foi a produção de matéria seca (DMY) em 2009, 2010 e 2011 em um experimento de campo em blocos casualizados com duas repetições. Cada amostra foi cultivada em diferentes condições ambientais. Os métodos de estabilidade testados foram de Yates e Cochran, Plaisted e Peterson, Wricke, Annicchiarico, Lin e Binns e Kang e Phan. Os resultados indicaram que o corte (E) e os genótipos (G) influenciaram significativamente no desempenho para a produção de matéria seca. Os métodos de estabilidade não-paramétrica foram eficientes para a avaliação da estabilidade no rendimento da matéria seca. Os genótipos Mercker, Pinda-México, Mercker 86-México, Guaçu/IZ, Mercker Pinda, P-241-Piracicaba e Cubano Pinda tiveram uma estabilidade estável na produção de materia seca. Por conseguinte, existem genótipos que podem ser explorados em futuros programas de melhoramento, a fim de melhorar a produtividade de capim elefante no ambiente.

Effect of nitrogen and potassium fertilization on morpho-agronomic traits of three elephant grass ( Pennisetum purpureum Schum.) genotypes for biomass production

Elephant grass has been proposed for the energy sector as a possible source of renewable energy, because of its high biomass production. The aim of this study was to evaluate the effect of the mineral nutrients nitrogen and potassium on the morpho-agronomic traits (dry mater yield (DMY), percentage of DM (%DM), number of tillers per linear meter (NT), plant height (PH), stem diameter (SD) and leaf blade width (LW)) in different elephant grass genotypes in a randomized-block experimental treatment in a split-plot arrangement with three replications, in which the genotype factor (‘Cuban Pinda’ - G1; ‘IAC Campinas’ - G2; and ‘Cameroon’ - G3) was randomized in the plot, and the N and K factor was randomized in the sub-plot. The increase in nitrogen and potassium doses utilized influenced very little or almost did not influence the response of the three genotypes for the different morpho-agronomic traits assessed. The three genotypes had high number of tillers, height, and stem diameter at the lowest N and K doses, demonstrating a possible trend of high doses not providing a highly significant increase in these traits. The study of DMY showed that under a low nitrogen dose and with increase in potassium concentrations, dry matter yield increased; however, as the nitrogen dose increased in associated with potassium doses, dry matter yield did not augment, but was rather suppressed. The three elephant grass genotypes: ‘Cuban Pinda’, ‘IAC Campinas’, and ‘Cameroon’, had average dry yields of 52.66, 50.60, and 48.57 t ha –1 , respectively. Results are highly promising and prove the possibility of using elephant grass as an alternative source for biomass production. Keywords: Renewable energy, mineral nutrients, production capacity