Influence of row spacing on the yield of ten cultivars of soybean (Glycine max (L.) Merrill) | Vpliv medvrstnega razmika na pridelek desetih kultivarjev soje (Glycine max (L.) Merrill)

In the period 2001-2005 block field trials with ten soybean cultivars (Glycine max (L.) Merrill): Aldana, Borostyan, Essor, Ika, Kador, Major, Nawiko, Olna, Tarna and Tisa with three repetitions have been designed on the experimental field at the Biotechnical Faculty in Ljubljana with the purpose of studying the influence of sowing density on crop yield. Planting of soybean was performed manually each year in the beginning of May using the 50 cm row spacing (wide rows) and 25 cm spacing (narrow rows), the distance between seeds in a row was 15 cm. In each case of row spacing, the soybean cultivar and the year of the experiment influenced the mean yield of the soybean. For the dense sowing, the significantly higher yield of soybean (3428 kg/ha) was detected compared to the thin sowing (2690 kg/ha). The significant influence of the cultivar was found in every year in case of the thin sowing, where the yield in the 2001 (the year of the drought) was significantly lower compared to other years. For the thin sowing, the most productive cultivar was the Borostyan (3974 kg/ha), the lowest mean yield was recorded for the cultivar Aldana (1472 kg/ha). For the dense sowing, significantly higher soybean yield was confirmed in 2005 (3760 kg/ha), compared to the years 2002 (3145 kg/ha) and 2003 (3239 kg/ha), when the yields were significantly lower. The cultivar Aldana recorded the lowest yield (2110 kg/ha) also in the case of dense sowing, while under the same growing conditions, the cultivar Tisa (5171 kg/ha) proved to be the most productive cultivar. Considering the length of the growing period and the yield, the medium late cultivars Borostyan, Essor, Tarna, Major and Olna and the medium early cultivar Nawiko could be recommended for sowing in central parts of Slovenia. Despite higher productivity of Tisa, Ika and Kador cultivars, their late maturity is less suitable for machine harvesting on lager land areas. Based on our data on productivity, growing period and other economically significant characteristics of soybean cultivars, together with selected row spacing, the experts will be able to suggest to producers cultivars and production practises to ensure high and dependable yields of soybean.