1297 AJCS 10(9):1297-1305 (2016) ISSN:1835-2707 DOI: 10.21475/ajcs.2016.10.09.p7747 Combining ability in elephant grass (Pennisetum purpureum Schum.) for energy biomass production Bruna Rafaela da Silva Menezes* 1 , Rogério Figueiredo Daher 2 , Geraldo de Amaral Gravina 2 , Antônio Vander Pereira 3 , Messias Gonzaga Pereira 2 , Flávio Dessaune Tardin 4 , Verônica Brito Silva 2 , Erina Vitório Rodrigues 2 , Maria do Socorro Bezerra Araújo 2 , Maria Lorraine Fonseca Oliveira 2 , and Brunno de Oliveira Almeida 2 1 Universidade Federal Rural do Rio de Janeiro, 28013-600, Seropédica, RJ, Brazil 2 Universidade Estadual do Norte Fluminense, 28013-600, Campos dos Goytacazes, RJ, Brazil 3 Embrapa Gado de Leite, 36038-330, Juiz de Fora, MG, Brazil 4 Embrapa Agrossilvipastoril, 78550-970, Sinop, MT, Brazil *Corresponding author: brunarafamenezes@hotmail.com Abstract The objective of this study was to estimate and evaluate the general and specific combining abilities of hybrid combinations for energy biomass production, adopting the methodology of Griffing as adapted by Geraldi and Miranda Filho in evaluation cuts referring to two periods, the wet and dry seasons, and in relation to total dry matter yield (TDMY). The experiment was conducted at Pesagro Rio, located in Campos dos Goytacazes, RJ, Brazil, in a randomized block design with three replicates. Crosses were performed in a partial diallel system. Treatments consisted of 10 parents, 25 hybrid combinations, and 1 control. Three evaluation cuts were made: two in the wet season and one in the dry season. The following traits were evaluated: plant height, stem diameter, leaf width, number of tillers, percentage of dry matter, dry matter yield, and TDMY. Regarding the general combining ability effects, the parents “Cameroon-Piracicaba” and “Mercker” showed outstanding positive values. Of the hybrid combinations, “Cubano Pinda”“Mercker”, “Cameroon-Piracicaba”“Três Rios”, “Cameroon-Piracicaba”“Mercker 86-México”, “IAC-Campinas”“Três Rios”, “IAC-Campinas”“Mercker 86-México”, and “Guaçu IZ.2”“Roxo” showed superior productive performance. Hybrids can be obtained with superior energy biomass production to that of the currently available elephant grass cultivars. Keywords: alternative energy; bioenergy; diallel; plant breeding; Pennisetum purpureum. Introduction Global warming in recent years has been a worldwide concern due to its effects on life on Earth. Such heating is derived from the high emission of greenhouse gases, such as carbon dioxide (CO 2 ), nitrogen atom oxides (NOx), and methane (CH 4 ), into the atmosphere after the Industrial Revolution. The amount of CO 2 is a recognized measure of environmental sustainability, and there is a common concern to reduce CO 2 emissions (Liu, 2014). Some crops have been used to achieve sustainable energy (bioenergy). Among them are castor bean and soybean, vegetable oil producers (Vaz et al., 2010), sugarcane (Viator et al., 2012), and elephant grass (Menezes et al., 2015). The elephant grass species (Pennisetum purpureum Schum.) is highly efficient in the fixation of atmospheric CO 2 , and it can produce 60 t ha -1 of biomass per year (Morais et al., 2009). Biomass energy production is already a reality in Brazil, and there is a current demand for species and varieties for cultivation in different regions. Biomass is a promising source of renewable energy, as it has significant economic and environmental advantages, e.g., it is low cost and can be used to reduce CO 2 emissions (Ibrahim et al., 2014). With the employment of perennial plants for biomass production and efficient systems in this conversion, approximately 250 million hectares in the world could be used in the development of the bioenergy industry. The improvement in biomass production and quality can be achieved with advances in plant breeding (Samson et al., 2005). According to Allwright and Taylor (2016), the main goal of the improvement of bioenergy plants has been increasing yield per unit area without environmental degradation or the increase of agricultural inputs. The study of productive traits in elephant grass is of great importance for the success of breeding programs that aim at increasing yields (Silva et al., 2008). According to Menezes et al. (2014), features such as high stem diameter (SD) and number of tillers per linear meter (NT) are positively correlated with the production of dry matter, i.e., plants with the highest SD and NT are more productive. Diallel analyses are useful in the estimate of parameters for the selection of parents for the hybridization and determination of the gene action controlling a trait. Thus, the presence of dominance deviations indicates that the exploration of the hybrid is favorable (Cruz et al., 2012).