Effect of sowing date and plant density on yield components and seed yield of soybean genotypes

In order to study the effects of different sowing dates and plant densities on soybean genotypes, an experiment was carried out in arandomized complete block design, arranged in asplit split plot design with four replications at the Agricultural Research Station of Baykola. Main plot was planting dates including 20 April, 20 May and 20 June, sub plots wereplant densities including 32, 40 and 48 plants per square meter and sub sub plots were soybean genotypes: Sari, Nekador and line 2002. Results showed that with a delay in planting date, most of the traits studied were decreased and consequently seed yield decreased. At the third planting datecompare to the first planting date, pods per plant, pods per main stem, seeds per pod and seed yield decreased 32.35, 22.29, 40.21, 46.85, 10.57 and 42.29%, respectively. Although there were significant differences among genotypes for some yield components, but there was not any significant difference among genotypes for seed yield. The average seed yields of genotypes at the first, second and third planting dates were 3235, 2577 and 1867 kg ha-1, respectively and they were also classified asthree different statistical groups. Due to non-significant effect of plant densiy on seed yield, for reduction of seed cost, 32 plants per square meter can be recommended.