BREEDING OF MINKANG 3 9 AS A VARIETY OF SWEET POTATO AND TEST FOR ITS RESISTANCE TO BACTERIAL WILT AND FOR ITS PRODUCTIVITY

As a new variety of sweet potato, Minkang 329 was produced by crossing Pushu 125 and Nanhui No. 3. The 1981-1935 green-house tests for 66 different virulent strains of sweet potato bacterial wilt (Pseadomonas solanacearum) showed that the mean index of disease infection was 7.4.In the field conditions, the death rate of seeding was 0.8%. In the field plots the mean index of disease infection was 2.5; in the diseased plots, 4.7 : lower than that of the local check variety Xinzhonghua. The results also indicated that Mingkang 329 matched China’s check variety Huabei 48 in the resistance to sweet potato bacterial wilt.Tests for its productivity in 72 diseased areas showed that the yield of Mingkang 329 was 31.6% higher than that of Huabei 48, 2.8-2.9 times that of Xinzhonghua. But in 53 disease-free areas and 23 yield estimating plots of Fujian Province, the yield of Minkang 329 increased by 10.8 -26.6% as compared with Xinzhonghua.Minkang 329 formed its tuber early. 25 days after transplantation, the tuber was formed out of young roots. The yield reached 3050 kg. per mu in 120 days.Under better cultivation,the average yield was more than 4500 kg. whether in mountain districts, plains or coastal sandy areas.From 1934 to 1986, Minkang 329 was introduced to 40 counties in Fujian. The accumulative cultivation area reached 800 thousand mu.The in-creased output altogether was more than 100 million kg. The social efficiency was over 30 million yuan. This variety was also introduced to the neibouring provinces and also showed higher yield in an area of 10 thousand mu.