Evaluation and Selection of Cassava Varieties (Manihot esculenta Crantz) for Good Food Quality and High Yield Potential

Abstract

Cassava is an economic industrial crop in Thailand which is used as raw materials for starch production, ethanol and plastic. It is a tuberous plant that accumulates starch at the roots and is highly tolerant to drought conditions. As a result, cassava has a potential to be an important food crop in the future that climate change may result in food shortages. In Africa and many Asian countries such as Indonesia, Cassava is used as food. In Thailand, cassava is also processed into food and desserts, but limited to Hanatee variety and Kolog variety only. Because they have low amount of cyanide content (below 50 milligrams per kilogram), but for other cultivars, There is a large amount of cyanide in the root (usually higher than 100 milligrams per kilogram) which is toxic to human and may be fatal if consumed in large quantities and it also has a bitter taste. But Hanatee  variety and Kolog variety have to be planted in irrigated areas only in order to produce high root yield. For this result, they cannot be grown in rainy areas with high productivity. Therefore, breeders have improved cassava varieties for high yield and low cyanide content for consumption purpose. In this research, it was a collection of cassava strains from many breeding programs from the Cassava Breeding Projects to have low head cyanide and high yield. (Under the support of NSTDA), Department of Agronomy, Faculty of Agriculture, Kasetsart University, consisting of 2 lines, Phirun 2, Rayong 2, Kolog, and cassava lines that contain cyanide in the leaves, KUKM 019, KUKM 031 and KUKM 045. By comparing the amount of cyanide with Hanatee variety, which is the variety that is commonly used for cooking and compare the root yield with Kasetsart 50 variety, which is the most popular commercial variety cultivated throughout Thailand. The results show that cassava lines that have been bred to have low cyanide content, although most of the varieties had root yield which were higher than Hanatee variety and the production and root starch percentage is similar to Kasetsart 50, they still not be able to have a low level of cyanide in root as safe as Hanatee variety over the 3 harvest periods at 8 months, 10 months and 12 months after planting. Therefore, despite the higher yields over Hanatee variety, all breeding lines should not suggested for farmers to grow for consumption because the amount of cyanide exceeds 50 ppm or grams per kilogram of fresh weight of root which may be intoxicate to the consumer especially Pirun 2 variety which have been suggested as cassava for consumption already. However, in this research, Pirun 2 variety has more than 50 ppm of cyanide in all harvesting times and more than 100 ppm when harvested in the 10th and 12th months. Cyanide content over 100 ppm is considered to be highly harmful for consumption.