Screening of potential cassava varieties for good tolerance under waterlogging conditions

The experiment screening of potential cassava varieties for good tolerance to artificial waterlogging was evaluated on 17 varieties of cassava in vitro at 3 months of age after planting in potting soil for 12 days through physiological parameters: number of leaves\plant, number of yellow leaves, number of wilted plants and chlorophyll content. The results showed that cassava varieties had different tolerance to waterlogging: some varieties showed physiological symptoms only after 3 days of growth on waterlogging conditions such as the number of leaves\plant decreasing to 83.93 %. 93.75 %, 93.81 %, 95.88 % and 96.48 % in cassava varieties C86, C23, Hanoi3, C84 and C31, respectively. After 6 days of waterlogging, the percentage of yellow leaves in some varieties of cassava had been increased, attained up to 40 % of the total leaves\plant turned yellow such as C71 (44.68 %) or C13 (53.12 %) varieties while other cassava varieties wilted and die 100 % such as Hanoi3, C10, C13, C34, C42, C66, C71, C84 and C86; along with the symtoms of morphological and growth of cassava varieties on waterlogging conditions, the total of chlorophyll content also decreased. After 9 days of waterlogging, only C60 variety remained chlorophyll content with 77.38 % but in other cassava varieties, the chlorophyll content was not more than 50 %. We founded that the longer the duration of waterlogging, the more tolerant response of the studied cassava varieties was revealed. After 12 days of experiment, we initially determined that the C60 variety was the best flood tolerance among the 17 studied varieties and this was a good source of materials on selecting the variety of flood tolerant cassava.