Soybean has been categorized as an important field crop of Thailand. Its production of approximately 5 hundred thousand tons per year is not sufficient for the domestic use. Consequently, large amount of grain soybeans has to be imported every year. In order to cope with this situation, the production efficiency needs to be improved and the use of improved varieties is one method, amongst several, available to address this problem.

Chiang Mai 3 or CG 81031-6-2-1 was derived from cross between G 9946 and AGS 17 (Higo Daizu x R-10) hybridised at AVRDC. It was introduced to Chiang Mai Field Crops Research Centre in 1991 and followed the steps of the soybean breeding program such as preliminary yield trials, standard trials, regional yield trials, field trials and finally yield tests. At each stage, the trials were conducted in both rainy and dry season conditions and in various soybean growing areas.

Results from these trials indicated that Chiang Mai 3 gave an average grain yield at 2,062 kg/ha, which was approximately 7% higher than that of the standard variety, Chiang Mai 60 (Table 1). It has also shown the similar good performance in both seasons.

Data from genotype x environment analysis indicated that Chiang Mai 3 could adapt well to almost all of the environments it was tested in. Data on the yield of Chiang Mai 3 at various locations, which can be seen in Table 2 and 3, showed the evidence to support this analysis.

The reactions of soybean to the major diseases such as leaf spot, downy mildew and soybean mosaic virus (SMV) were also recorded and showed that Chiang Mai 3 had good resistance to these diseases (Table 4)

For quality in terms of oil content and protein, Chiang Mai 3 had higher oil content than Chiang Mai 60 and was similar in protein (Table 5)

CM3