Summary

Two dry bean cultivars (Umtata – a single-time flowering variety, and Kranskop – a continuously flowering variety) reported to be suitable for growing under conditions prevalent in the area around Pietermaritzburg are studied. A randomised block factorial experiment was planned and carried out at Ukulinga Research Farm of the University of KwaZulu Natal to compare growth and yield of the two cultivars at different seeding rates and with and without nitrogen side-dressing. The design, layout and sampling of the experimental plots are described.

Total biomass and grain yield after three months of growth are analysed. Total biomass was higher in the Kranskop than the Umtata cultivar but grain yield was lower. Seeds were planted at a 75 cm between-row spacing and at three different within-row spacings: 5 cm, 10 cm and 15 cm apart. Biomass and grain yield increased in a linear manner with decreasing spacing. Application of nitrogen fertiliser had no effect. There were no significant interactions involving cultivar, level of spacing or fertiliser application.

Plant height and number of leaves were measured weekly over a four-week period after the start of emergence. Analysing weekly data together results in a split-plot in time model. The difference between this and the conventional split-plot experiment is described and methods of analysis outlined. Kranskop plants grew higher than those for Umtata over the four-week period.

The difference in cultivar type (continuous versus single flowering) is considered to be the primary reason for differences in plant growth and yield. Planting later in the season than is normal practice may also have had a bearing on the way the two cultivars performed.