Three varieties in one cassava trial and five in another were planted in a systematic density experiment which showed that optimum plant density for root yield changes with plant age. Some varieties showed a pronounced optimum plant population, whilst others showed a flattopped response curve. Reduction in yield above the optimum is due to a reduced harvest index. Yields of over 50 t–ha were obtained with varieties that respond to close spacing.

A diallel analysis of flowering time, pod number, 100-seed weight and yield of six cultivars of Cajanus cajan (L.) Millsp. was studied. Additive inheritance was important in determining flowering time, but the dominance component was higher than the additive component, and over-dominance was observed for pod number, 100-seed weight and yield. Heritability estimates for all the traits except flowering time were quite low, and the bulk population method of breeding was suggested for early segregating generations. The graphical analysis of the diallel cross was in close agreement with the findings from variance component analysis. It is suggested that the best cross would be that between two parents chosen on the basis of their low g.c.a. for flowering time and their high g.c.a. for other traits.

The effect of sowing time and variety were tested for three consecutive years under irrigated conditions. The relation between yield and planting time was quadratic, best described by y=a+bx-ex2 where y is grain yield and x is planting time. The results showed that, irrespective of variety, the optimum sowing date is around mid-November. Varietal differences are related to number of ears per unit area, with a stronger association of yield with grain weight than with any other yield components.

Forty-six cultivars of linseed oil (Linum usitatissimum L.) were grown under wet and dry season conditions in the Sudan Savanna of Nigeria. Only during the dry season was production good and cv Dunes consistently outyielded all other cultivars in terms of seed and oil content. Trials of sowing dates gave maximum seed yield and oil content from plots sown during late October. In row spacing trials, rows 15–22 cm apart and seed rates of 58–78 kg/ha were found to be the most practicable. There was a linear relation between increasing rates of nitrogen and seed yield, maximum production being obtained at 55–88 kg N/ha, but oil content was slightly depressed at levels above 33 kg N/ha.

Dodoma Edible outyielded Natal Common groundnut, due to varietal effects associated with differences in pod number, leaf area duration, crop growth rate, number of grains/pod and m2, and weight of individual grain. Increase in plant density led to an increase in grain yield. There was a close and positive relation between stem and pod dry weight; grain yield and leaf area duration; and crop growth rate, grain yield and grain number/m2 of land surface. A greater proportion of total dry matter was diverted into the stems of Dodoma Edible than Natal Common.

An investigation was carried out to study the effects of boron (0, 1, 2 and 3 kg/ha) and nitrogen (0, 50, 100 and 200 kg/ha) on the growth and yield of radish cv Pusa Rashmi. Various growth characters such as number, fresh weight and dry matter content of leaves, and length, girth, fresh weight and dry matter content of roots increased with increase in boron and nitrogen levels, the highest application of both nutrients giving the best results. Treatment combinations showed significant effects on fresh weight of leaves and roots, with the best results from 3 kg boron + 200 kg of nitrogen/ha.