Groei en ontwikkeling van sojabooncultivars by verskillende rywydtes

English: Several studies in especially the United States of America showed that soybeans produced higher yields when planted in narrow rows as opposed to wide rows. The higher yields were mostly attributed to better solar interception as a result of a higher leaf area index. A denser leaf canopy increases water use efficiency and decreases weed competition. Therefore the influence of cultivars and row spacing on the growth and development of soybeans was evaluated. The experiments were conducted at two divergent localities, namely Bergville, Kwazulu-Natal and Bloemfontein, Free State during the 2000/01 and 2001/02 seasons with six cultivars (PAN660/564, Dumela, A5409, LS666, Tops and SNK500) and two row spacings (0.45 and 0.90 m). An effort was made to use or imitate commercial cultivation practices. Several plant physiological components were measured, namely during the flowering stage: plantheight, leaf mass, number of leafs, number of branches and leaf area index; and during physiological ripe stage: number of pods, pod mass and seedmass. During the flowering stage the nutrient concentrations in the above ground plant material was also determined. The water use efficiency over the growing season was also quantified. Neither the cultivars nor the row spacing had a significant influence on nutrient concentrations in the above ground plant material. The water use efficiency, although not statistically analyzed, was higher at the narrow than wide rows. Most of the above ground plant components that were measured had higher values at the 0.45 than 0.90 m rows. The one plant component that stood out in this regard was the number of branches that developed per unit surface area. When soybeans is planted at the same density in the 0.45 and 0.90 m rows the distance between adjacent plants in the narrow rows (0.074 m) is twice of that in the wide (0.037 m) rows. The consequence thereof was that the soybeans developed significant more branches in the narrow than wide rows. The more branches in the narrow rows resulted in a more bushy plant which broaden quicker. As a result of this together with the smaller distance between adjacent rows the soil surface was covered faster and therefor a higher leaf area index at the narrow than the wide rows. This higher leaf area index at the narrow than wide rows is in accordance with results reported by other researchers. They suggested the higher leaf area index resulted in earlier and higher solar interception. Although seed yields differed not always significantly between the narrow and wide rows, the yields were consistent higher at the narrow rows. Soybeans should be therefore rather planted in narrow (0.4 - 0.6 m) than wide (0.8 - 1.0m) rows if possible. An aspect that warrants investigation is the planting of soybeans at different densities in the narrow rows.