Yield Enhancement of Soybean (Glycine max l. Merill) in Genotypes 'Polije-4' and 'Polije-5' through Backcross with Large Seed Donor Parent

Soybean is one of important crops in Indonesia because of its role as a source of vegetable protein and it is used as an industrial raw material. However, national soybean production cannot keep up with the need. Hence, large amount of import is required to meet national needs. This study aims to assemble new high yielding soybean varieties, which have high yield (>3 ton/ha), early maturity (harvest age <76 days), large seed (>15 g) and have moderate resistance to major soybean disease, the leaf rust, caused by Phakopsorapachyrhizi. In the previous research, soybean genotypes which fit to the criteria above have been obtained, namely 'Polije-4' and 'Polije-5'. However, these genotypes have a major drawback which is the small size of the seed (around 13 g/100 seeds). This drawback can be repaired by using the recurrent backcross method with 'Ryokko' edamame as the donor parent, which has a distinctly large seed size around 35 g/100 seeds. In the current research, this backcross method between 'Polije-4' and 'Ryokko', as well as 'Polije-5' and 'Ryokko' was conducted and resulted in the increase of yield(>20 g/plant) and seed size (>15 g/100 seeds), but still maintaining the early harvest age ( 76 days).