-The objective of this study was to evaluate the agronomic divergence of 25 sorghum hybrids (Sorghum bicolor L. Moench) in the semiarid region of Paraiba. A randomized block design with three replications was used for evaluation of plant height (PH), total natural matter production (TNMP) and total dry matter production (TDMP) and the percentage of components of DM (panicle, leaf blade, stem and dead matter) of the following hybrids: 866005, 866019, 866033, 866034, 866035, 866036, 866037, 866040, 866041, 866042, 866043, 866044, 870025, 870031, 870035, 870041, 870051, 870067, 870081, 870085, 870095, 1F305, BRS 610, Volumax, and XBS60329. Hybrid 1F305, followed by hybrid 866034, presented the highest average PH. There was a range from 7.679 to 20.948 kg/ha (average of 13,799 kg/ha) for TDMP. Hybrids 1F305, BRS 610 and Volumax presented less potential, and hybrids 866,041 and 866,042 were the most productive. Based on cluster analysis and subjective cut in 50% of dissimilarity, it was possible to establish four hierarchical groups, from which two stood out concerning productive characteristics. The group formed by hybrids Volumax, BRS 610, and XBS60329 presented lower averages for yield and lower percentage of panicle. Hybrids 866041 and 866042 show a higher total dry matter production, with values around 20,000 kg/ha.

Características agronômicas e efi ciência do uso da chuva em cultivares de sorgo no semiárido.Ciência Rural, v.43, n.10, out, 2013. 1771Características agronômicas e efi ciência do uso da chuva em cultivares de sorgo no semiárido INTRODUÇÃOA região semiárida do nordeste brasileiro é caracterizada pela ocorrência de precipitações que se distribuem de maneira irregular, concentradas num curto período chuvoso, seguido de um longo período sem chuvas. Essa característica climática é o principal fator que afeta a produção agropecuária dessa região, sendo importante a aplicação de estratégias específi cas para obter maior rendimento na produção de forragens.A escassez de forragem, agravada no período seco, e o baixo valor nutritivo das forrageiras de ocorrência natural comprometem o crescimento e o desenvolvimento dos animais, acarretando queda de produtividade e comprometendo a produção de leite e

-The objective of this study was to evaluate agronomic characteristics of 32 sorghum cultivars (Sorghum bicolor (L). Moench) in the Brazilian semi-arid region. The experimental design was set up in randomized blocks with three replications. Treatments were the 32 sorghum cultivars. The evaluated variables were: plant height, stem diameter, tiller density, number of green leaves per tiller, average leaf length, dry matter content, fresh matter production and dry matter production (DMP) in kg/ha, and the percentage of the components panicle, leaf blade and stem. To avoid associative effects due to the presence of positive correlation with DMP, the variables plant height, number of plants per hectare and fresh matter production were excluded for being part of the discriminatory variables of the cluster. Based on the cluster analysis and subjective cutting in 20% dissimilarity, five groups were hierarchically set up. It was not possible to find groups with higher values of panicle and DMP simultaneously; however, group number 5 met significant values for both variables, with mean values of 15,037.63 kg/ha of DMP and 11.36% of panicle, besides 13.65% of leaf. Groups 3, 4 and 5 show high potential for dry matter production, especially group 5. The presence of evident variation among cultivars allows for a selection of more productive and, thus, more suitable cultivars for silage production in semi-arid regions.

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The objective of this chapter was to discuss the importance of the fermentation processes for silage making and how it affects the final quality of the silage. The preservation of the forage crops as silage is based on a fermentation process that lows the pH and preserves the nutritive value of the fresh crop. The main principle is the production of lactic acid by the lactic acid bacteria from the metabolism of the water-soluble carbohydrates in the fresh crop. However, different fermentations may occur into the silo environment and it depends on the availability of substrate, the microbial populations, the moisture content, and the buffering capacity of the crop at the ensiling. The fermentation is quite important in the ensiling process because it affects the nutritional quality of the silage and the animal performance. If the fermentation does not occur as recommended and the undesirable fermentations will take place, which will result in a total spoiled feed that is potentially risky for animals and human's health. Well-fermented silage can be used in diets for ruminant animals without any risk for their health and without compromise the productive performance.

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Objetivou-se com esta pesquisa avaliar o rendimento forrageiro, as características agronômicas e morfométricas das plantas e as perdas, perfil fermentativo e composição bromatológica de silagens de genótipos de milheto. Para avaliação das características agronômicas e morfométricas dos genótipos utilizou-se o delineamento experimental em blocos casualizados, com cinco repetições. Na fase de avaliação dos silos experimentais o delineamento passou a ser inteiramente casualizado, com quatro repetições. Foram testados os cultivares Sauna B, CMS 01, ADR 500, BRS 1501 e CMS 03. Não houve diferença para a PMV, PMS e MS. Os genótipos de milheto apresentaram uma média de PMV de 9.073 kg/ha no primeiro ciclo e de 10.054kg/ha na rebrota. Quanto à lâmina foliar e a produção de colmo não houve diferença em ambos os cortes. Os teores médios de AL variaram de 1,98 a 5,17%, para os genótipos SAUNA B e CMS 01, respectivamente. Para os teores de PB verificou-se efeito significativo entre os genótipos estudados, com valores variando de 11,56 a 7,90%. Os genótipos estudados se equivaleram tanto na avaliação das plantas como na avaliação das silagens, podendo ser utilizados como uma alternativa forrageira em regiões semiáridas.