Recent Advances in \u3cem\u3eStylosanthes\u3c/em\u3e Research in Tropical America

The potential of neotropical savannas is very large for pasture-based livestock systems. There are 250 million ha of well-drained lowland savannas in the American tropics. Over 200 million ha are situated in the Cerrados region of Brazil. The Cerrados support 42% of the national herd. Although these ranges support large populations of livestock, productivity is generally low. Poor nutritive value of native pastures and monospecific swards of Brachiaria spp. is the principal cause of this low productivity, especially in the dry season when these grasslands often provide no more than 60% of the animal\u27s maintenance requirements. The best option to increase pasture/livestock productivity is the use of improved pastures, particularly those based on adapted tropical legume-grass associations. Research in tropical America was concentrated on the evaluation and selection of Stylosanthes species adapted to low fertility acid-soils and resistant to anthracnose (Colletotrichum gloeosporioides). Anthracnose is considered the major limitation to the commercial use of Stylosanthes on a world-wide basis

Estilosantes Campo Grande in Brazil: A Tropical Forage Legume Success Story

Estilosantes Campo Grande (ECG) is a mixture (80/20 by weight) of Stylosanthes capitata and S. macrocephala, derived through genetic combination of selected accessions by open crossing over 6 generations (Grof et al., 2001). The cultivar is the result of \u3e10 years of research on a collection of \u3e1000 ecotypes of Stylosanthes species collected and maintained by Embrapa. The main use of ECG in Brazil is to improve grass-dominant pastures. It has good persistence with Brachiaria spp., Panicum maximum (Tanzania-1 and Mombaça) and Andropogon gayanus. It has excellent adaptation to low fertility sandy soils and is persistent under grazing. In regional trials, ECG was the best performer in S Brazilian Cerrados, where the dry season is less severe. Although it does not retain foliage after the rainy season in areas with long and intense dry season, it still contributes to nitrogen fixation and animal nutrition during the rainy season. It is a prolific seed producer and seedling recruitment is its main mechanism of persistence. More than 500t of ECG seed has been produced since its commercial release and the estimated area planted to this cultivar has increased from \u3c500ha in 2000 to nearly 150Kha by 2004, mainly in the Brazilian Savannas

Controle da podridão gomosa em melão rendilhado em cultivo protegido por sanitização de ferramenta de poda

A podridão gomosa (Didymella bryoniae) é a principal doença para o meloeiro rendilhado (Cucumis melo) cultivado em estufas no Norte do Estado do Paraná e a poda das brotações laterais das plantas tem sido eficiente meio de disseminação do patógeno. Este trabalho teve como objetivo estudar o efeito da desinfestação da tesoura de poda com hipoclorito de sódio (2%), no desenvolvimento da podridão gomosa em meloeiro rendilhado cultivado em estufa plástica. Foram utilizados os híbridos Bônus II e Sunrise em oito estufas, localizadas em diferentes propriedades em Maringá, Paraná. Avaliou-se a incidência da doença através da percentagem de plantas com alguma necrose no caule, a percentagem de plantas mortas e o brix e a produtividade dos frutos. Os resultados mostraram a alta eficiência da técnica de desinfestação da tesoura de poda no controle da doença. Para Bônus II e Sunrise, podados com tesoura desinfestada, a percentagem de plantas com necrose no caule variou de 27,5 a 12,5 e de 20,0 a 7,5, respectivamente. Ainda com esse tratamento, a percentagem de plantas mortas variou de 7,5 a 2,5 e de 10,0 a 2,5, respectivamente, para Bônus II e Sunrise. Para Bônus II, sem desinfestação da tesoura de poda, registrou-se variação percentual de 62,5 a 100 e de 30,0 a 100 de plantas com necrose no caule e de plantas mortas, respectivamente. Já, para Sunrise, a percentagem de plantas com necrose no caule e de plantas mortas, quando a tesoura não foi desinfestada, variou de 42,5 a 100 e de 10,0 a 87,5, respectivamente. O procedimento de sanitização proporcionou elevado incremento no brix e na produção de frutos.Gummy stem blight on cantaloupe melon (Cucumis melo), caused by Didymella bryoniae, has been a very destructive disease in Northern Paraná State, Brazil, where it can cause yield losses of up to 100%. This pathogen is believed to be spread inside plastic greenhouses mainly through the cutting tools used for removal of shoots from plants. The objective of this study was to evaluate the effect of sanitation on the disease progress by washing scissors used for cutting shoots in 2% NaClO. Experiments were set up in commercial plastic greenhouses for a period of two years using two cantaloupe melon hybrids, 'Bônus II' and 'Sunrise'. Disease intensity was assessed through incidence, expressed by the percent of plants showing necrosis on stems and the percent of dead plants, fruit brix and yield. The results showed that i t is possible to reduce the spread of rot gumosis inside the plastic greenhouse by washing the cutting tools in 2% NaClO. In 'Bônus II', sanitation was observed to reduce the percentage of plants showing necrosis from 62.5-100% to 12.5-27.5%, and the percentage of dead plants from 30.0-100% to 2.5-7.5%. In "Sunrise", sanitation reduced the percentage of plants showing necrosis from 42.5-100% to 2.5-10%, and the percentage of dead plants from 10-87.5% to 2.5-10%. Sanitation increased 'Bônus II' yield from zero-19.88 ton.ha-1 to 26.78-27.61 ton.ha-1 and 'Sunrise' yield from 4.5-21.34 ton.ha-1 to 26.86-28.34 ton.ha-1. Also, sanitation increased fruit brix in both cantaloupe melon hybrids

BRS Paiaguás: A New \u3cem\u3eBrachiaria\u3c/em\u3e (\u3cem\u3eUrochloa\u3c/em\u3e) Cultivar for Tropical Pastures in Brazil

Approximately half the world’s beef is produced in the tropics and subtropics, almost exclusively on pasture. While the world production of beef and veal increased 91% over the past 40 years, the increase in the tropics was 200%. Brazil has today the largest commercial cattle herd in the world (about 190 M head) and is the world\u27s largest exporter of beef. The area of cultivated pasture increased from 30 to 100 Mha between 1970 and 1995 (IBGE 2006). This area has now stabilised or decreased despite the increase in beef production, which reflects the gain in area productivity. Part of the cultivated pasture expansion till 1995 resulted from the replacement of native pasture, and part from the opening of the Brazilian Cerrados, but the main contributing factor to the increase in livestock production was the use of more productive cultivars and intensification in the management of cultivated pastures. The demand for productive and high quality forages continues to be high. Very few cultivars are commercially available, and the majority of these display apomictic reproduction, resulting in no novel genetic variation. New cultivars are urgently needed to increase pasture diversification as insurance against the extensive mono-cultures formed in central Brazil. The cultivars released mainly by Embrapa, were developed mostly by selection from the natural variability in germplasm collections, reflecting the success of this methodology, and account for over 70% of the forage seed available commercially. This paper presents data on a new cultivar of Brachiaria brizantha, selected for soils of medium fertility with a well defined dry season

BRS Quênia and BRS Tamani: New \u3ci\u3ePanicum maximum\u3c/i\u3e Jacq. Hybrid Cultivars in Brazil

Since 1982 Embrapa Beef Catle in Campo Grande, MS, Brazil, develops a Panicum maximum Jacq. breeding program, based on the germplasm collected and assembled by IRD (Institut de Recherche pour le Developpment) and received through a cooperation-agreement with IRD. The germplasm was evaluated and four cultivars were released directly from the germplasm: cultivars Tanzania, Mombaça, Massai and BRS Zuri. Breeding began in 1990 and involved crosses between sexual plants and selected apomictic accessions. The program consists of evaluation followed by selection of hybrids in plots with replications, evaluation of the selected hybrids in national network experiments in diverse regions and then evaluation of the few selected hybrids under grazing. Hybrids are also evaluated for disease and insect resistances and abiotic stresses. Seeds are multiplied between each evaluation phase. The whole process takes from 10 to 20 years for the release of superior cultivars. Recently, Embrapa released two hybrid cultivars. BRS Tamani, a short, very leafy and high-tillering cultivar, and BRS Quênia, a medium height, very leafy productive cultivar. Both cultivars are recommended for medium to high fertility light soils, corrected for soil nutrients, and for rotationally grazed management. BRS Tamani, because of its short stature and quality is well indicated for cattle weaning. Both cultivars are tolerant to all the spittlebugs present in Brazil. They are not suited for waterlogged soils. Compared to the traditional cultivars in Brazil, these two cultivars showed improved digestibility and crude protein and greater animal daily gains and BRS Quênia also provided higher liveweight gain per area