Forage Grasses and Legumes with Broad Adaptation for Southeast Asia

A wide range of forages is currently being evaluated by farmers and researchers in seven countries in Southeast Asia. Broadly-adapted species have been identified for fodder banks, grazed systems, tree cropping, erosion control and improved fallows. The most promising accessions to date are Stylosanthes guianensis CIAT 184, Brachiaria decumbens cv Basilisk, Brachiaria humidicola cv Tully and CIAT 6133, CIAT 6780, Centrosema pubescens CIAT 15160 and Andropogon gayanus cv Kent and CIAT 621. Other forages that show promise are Paspalum atratum, Arachis pintoi, and Macroptilium gracile cv. Maldonado. Local seed supply and distribution systems are needed to ensure that these species reach their potential on farms

Cassava genome from a wild ancestor to cultivated varieties

Cassava is a major tropical food crop in the Euphorbiaceae family that has high carbohydrate production potential and adaptability to diverse environments. Here we present the draft genome sequences of a wild ancestor and a domesticated variety of cassava and comparative analyses with a partial inbred line. We identify 1,584 and 1,678 gene models specific to the wild and domesticated varieties, respectively, and discover high heterozygosity and millions of single-nucleotide variations. Our analyses reveal that genes involved in photosynthesis, starch accumulation and abiotic stresses have been positively selected, whereas those involved in cell wall biosynthesis and secondary metabolism, including cyanogenic glucoside formation, have been negatively selected in the cultivated varieties, reflecting the result of natural selection and domestication. Differences in microRNA genes and retrotransposon regulation could partly explain an increased carbon flux towards starch accumulation and reduced cyanogenic glucoside accumulation in domesticated cassava. These results may contribute to genetic improvement of cassava through better understanding of its biology

Status of Stylosanthes development in other countries.II. Stylosanthes development and utilisation in China and southe-east Asia

Introduction of Stylosanthes species to south-east Asia commenced in 1949 and tended to follow the development of commercial cultivars in Australia. S. guianensis cultivars were introduced to humid and subhumid areas in Malaysia, Indonesia, southern Thailand, Philippines and China. S. humilis, S. hamata and S. scabra were introduced to drier areas in the region such as north-east Thailand, eastern Indonesia and southern China. Anthracnose severely reduced growth and survival of many cultivars used in the region. In 1976, an outbreak of anthracnose in S. humilis prompted a change to S. hamata cv. Verano in Thailand. S. guianensis cv. Schofield was similarly affected in many countries and was replaced by Cook and Graham. Later Cook and recently Graham were similarly affected in many countries and are being replaced by S. guianensis CIAT 184. The most widely used species today are S. hamata cv. Verano, and S. guianensis cv. Graham and CIAT 184. S. hamata is used mainly in north-east Thailand for inclusion in heavily grazed pastures. In 1995, 150 t of seed of S. hamata was produced in Thailand. S. guianensis cv. Graham and CIAT 184 are grown on more than 100 000 ha in monoculture, often associated with perennial tree crops in southern China. It is used as fresh feed for ruminants, or dried and processed as leaf meal. Recently, S. guianensis CIAT 184 has gained popularity in more countries in south-east Asia because of its broad adaptation, potential for multiple uses and high productivity in acid, infertile soils. Prospects for increased use of this species, particularly in smallholder farming systems, are excellent

Selection of high yielding and anthracnose resistant Stylosanthes for Brazil, India and China

Resistance to anthracnose, dry matter yield (DMY) and seed yield (SY) was assessed for germplasm and breeding lines of Stylosanthes in Brazil, India and China. Overall, Stylosanthes guianensis produced higher D MY than S. scabra, S. capitata and S. macrocephala at most sites in Brazil. Data from China suggest that there are high yielding anthracnose resistant S. guianensis lines that can reduce the reliance on CIAT 184. S. seabrana might also prove successful. S. seabrana in India produced the highest D MY and SY and it can form nodules with native Bradyrhizobium strains. Regional differences in resistance within accessions stress the importance of targeting germplasm to combat the suite of pathogen races present at a local level