Forage soybean production for seed in mediterranean environments

Despite several experiments on row spacings and seeding rates of grain soybeans, limited information is available on the most suitable row spacing and seeding rate for tall and robust forage type soybeans grown for seed. The objectives of this study were to investigate seed yield, oil and protein content, and several morphological traits as affected by row spacing (20, 40, 60 and 80 cm) and seeding rate (330,000, 660,000, 990,000 and 1,320,000 seeds ha−1) in tall and robust forage type soybeans in three irrigated Mediterranean environments in Turkey in a randomized split plot design with three replications in 2004 and 2005. Row spacings had no significant effect on plant height but tall and profusely branched plants developed in wide row spacing and light seeding conditions. Seed yield responded positively and linearly to row spacing up to 60 cm and then decreased slightly in all locations. Seed yield was the highest at 990,000 seeds ha−1 seeding rate in all three locations (3072.5 kg ha−1 in Bursa LSD = 214.7 kg ha−1, 3295.1 kg ha−1 in Mustafakemalpasa LSD = 298.6 kg ha−1 and 3311.3 kg ha−1 in Samsun LSD = 321.1 kg ha−1). Averaged across years, locations, row spacings, and seeding rates the mean seed yield was an impressive 3013.4 kg ha−1 compare with 3500.0 kg ha−1 average seed yield of grain types. Crude protein and oil content of forage type soybean were not significantly affected by row spacings and seeding rates. It was concluded that forage type soybeans can be grown for multiple purposes at the 990,000 seeds ha−1 seeding rate and 60 cm row spacings in Mediterranean environments.