Evaluation of the genetic diversities of crops, and their nutritional values for animal production, in the Mekong Delta of Vietnam

抄録

This experiment was conducted into the impacts of diversity loss and as a re-evaluation of the nutritional resources originating from agricultural crops, because there is no conservation strategy for either wild crop species or locally adapted cultivars used for human and animal consumption. Three important agricultural crops were investigated: soybean Glycine max, sweet potato Ipomoea batatas, and coconut Cocus nucifera, with five varieties of each collected for protein electrophoresis using the SDS-PAGE method. Crude protein (CP), ether extract (EE) and amino acids (AAs) of each of the representative samples were determined. The total oil was extracted from each sample and analyzed for its fatty acid (FAs) composition. Results showed that five soybean varieties 'MTD65', 'MTD176', 'Nam Vang C', 'Nam Vang H' and 'Can Tho 4' varied little from each other as shown by the fact that all sample individuals of each variety showed similar bands, indicating that they were in fact neither diverse nor pure genetic varieties. The CP content of soybean seeds ranged from 37.5-41.7% and EE content ranged from 20.4-22.1%, while methionine ranged from 0.2-0.6% and linoleic acid from 40.4-55.0%. Among the sweet potato varieties, 'Hong Dao', 'Hsinchu', 'Duong Ngoc' and 'Lang Bi', were diverse in phenotype (Ho), genetic marker (H_<EP>), and the sum of the effective number of alleles (SENA), while the 'Hong Ngoc' variety was not diverse (Ho=0), e.g all individual samples proved to share the same genetic material; the CP and EE content of the leaves ranged from 19.8-26.8% and 4.8-5.8%; while lysine ranged from 0.48-1.07% and linolenic acid from 39.7-45.5%. Among the coconut varieties, 'Bi', 'Lua', 'Ta Xanh', 'Ta Dai' and 'Dau', were diverse, although the 'Lua' variety was less diverse (Ho=1) than the others (Ho=1.9-2.3); the copra CP ranged from 7.7-9.0%, the amino acid contents were very small compared with those of the soybean varieties; EE content ranged from 65.0-71.6% and lauric acid from 44.4%-49.9%. These three crops are currently producing decreasing yields, and suffering genetic erosion mainly due to insect damage or as a result of being replaced by new high yield varieties, thus the direction of selection, conservation and improvement of each of the breeds should be based on our data.