Kousar, a New Soybean Cultivar Suitable for Spring Cultivation in Moderate Regions

Release of early maturity and tolerant soybean cultivars to phythophtroa disease has a significant effect on development of cultivation and production of this crop in the temperate climate of the country, especially the temperate regions of Lorestan province, that have a good potential for producing soybean in the country. In order to generate and release early mature soybean cultivars, a corporative project conducted by Seed and Plant Improvement Institute (SPII) and Atomic Energy Organization of Iran in 1372 in which seeds of Clark var. were exposed with gama ray. The irradiated seeds were sown in field and were evaluated for the mutated agronomic traits for 4 successive generations and eventually 47 early mature mutants were selected. Finally, after evaluating the selected mutants in the preliminary and adaptability yield trials, M.7 mutant was found as a superior genotype based on its early maturity and desirable grain yield. This mutant with 110 day growth period was 15 day earlier than Clark variety and also with grain yield of 3300 Kgha-1, its yield was 500 Kgha-1 higher than early mature variety TMS. Complementary experiments showed that M.7 mutant is tolerant to water deficit conditions and resistant to root and stem rot disease caused by phythophtora soja. This mutant was released as Kousar by Cultivar Release Committee of Iran in 1394.