The effects of intercropping roselle with blackgram, cowpea, soyabean, groundnut and sesame under single, double and triple row planting patterns and at three different intercrop sowing dates were studied from 1983 to 1985. The fibre yield of roselle was reduced by intercropping. The reduction was least with groundnut and greatest with cowpea but was compensated for by the yield of the intercrops. Double and triple row planting systems favoured the productivity of both roselle and the intercrops, increasing the Land Equivalent Ratio (LER) of the cropping system. The best yields of roselle were obtained when the intercrops were sown 15 days after the roselle.

Cultural standards and the husbandry techniques used on small farmers' fields are seldom the same as those practised on research and experimental Stations in the developing countries. The need for extensive agronomic experiments to be sited on small farmers' fields is emphasized. This method has been quite widely used with annual crops, but could with advantage be more generally adopted in perennial crops. Some of the advantages of this approach in agronomic investigations are illustrated by examples from work carried out in East Africa.

A comparison has been made of drip and conventional check basin methods of irrigation, using onions and ladies finger as test crops. Significant increases in yield and water use efficiency in drip irrigated over conventionally irrigated plots resulted from increased availability of soil moisture at low tensions and reduced surface evaporation losses. Reduced soil strength in drip irrigated plots was also a factor resulting in increased yield of onions.

In three field experiments, peat pH increased in parabolic relation to liming at the rate of 0.0544 pH unit/t/ha between 0–40 t/ha lime, but only 0.0224/t/ha between 40–72 t/ha. Groundnut and sorghum seed yield and crop residue also showed parabolic responses to peat pH and liming, but groundnut seed yield correlated poorly with soil pH (r2 = 0.38, P = 0.05), compared with its crop residue as well as with sorghum seed and residue (r2 = 0.75, 0.76 and 0.79, respectively, P = 0.01). Groundnut was generally more tolerant of peat acidity (pH 3.35–3.65) than sorghum, giving higher plant survival in unlimed plots, optimum seed and residue at pH 4.60 compared with 5.70 for sorghum, and reduced responsiveness to pH increase. Seed and residue of both crops decreased with continuous cropping, probably because of increasing pest and disease incidence and depletion of available soil nutrients.

Twenty-five cultivars of soyabean (Glycine max (L.) Merr.), differing in their origin, crop duration and seed size, were planted four times at bi-weekly intervals during the major rainy season at Ibadan, Nigeria and harvested at optimum maturity or two weeks later. Delayed harvest and intense rainfall during pod maturation were essential for selecting for resistance to field weathering, but 2 weeks' delay enabled susceptible and resistant cultivars to be identified. Percentage of infected seed had the highest correlation with potential germination at harvest (r=−0·869**) but may not be a suitable criterion for use in a screening programme. An alternative would be to screen cultivars for resistance to weathering on the basis of seed size and the proportion of smooth and clean seed, since these characters were highly correlated to potential germination (r=−0·562** and 0·632** respectively).

The possibility of growing grasses of higher quality than tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated with and without irrigation at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and a perennial ryegrass × meadow fescue hybrid cultivar in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Tall fescue persisted satisfactorily throughout the experiment, even without irrigation. With irrigation, the other three grasses persisted satisfactorily to the end of the second harvest year and fairly satisfactorily to the end of the third harvest year. Without irrigation, the other three grasses had incomplete ground cover in the second harvest year and did not recover from the third winter.

In nine breeding trials with cocoa in Ghana the experimental trees were interplanted with temporary trees of a standard variety as ‘calibrators’. The calibrators were removed after 2–2½ years before there was strong competition with the permanent trees. Trunk diameters of the calibrators were used as covariates in analyses of trunk size and yield of dry cocoa up to 7 years after planting, giving reductions in standard errors of differences between progenies of up to 25% in analyses of size and 15% in analyses of yield.

The quality of bean pods was influenced to a large degree by the variety, season of planting and the precise time of harvesting. The varieties Tenderette, Executive and Bush Blue Lake 274 were outstanding in their concentrated yield and pod quality. The development of seeds in the pods was faster in beans planted during the spring than in the autumn. Thickening of the pods during ripening was more rapid in the autumn than in the spring season. Outstanding differences were found between varieties with regard to the speed of seed development during pod ripening. As opposed to the outstanding differences between varieties with regard to quality characteristics, the differences with regard to yield were generally small and without economic importance.

The amount of starch in branches of Coffea arabica L. was studied by means of a method of visual scoring. In cropping branches, the variation in starch level was greatly, but not completely, determined by the growth of the crop. More knowledge of the formation and distribution of the products of photosynthesis is needed before a satisfactory explanation can be offered. Starch levels in non-cropping branches were higher than those in the cropping branches, but followed the same pattern of fluctuation. In general, translocation of starch occurred rapidly throughout the tree but some exceptions to this rule were found.

The possibility of producing herbage of higher quality than that of tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated, with and without irrigation, at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and perennial ryegrass × meadow fescue in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Perennial ryegrass yielded well in the year of sowing, but was low yielding subsequently; perennial ryegrass × meadow fescue yielded well in the year of sowing and in the following year. Both of these grasses had high rates of leaf appearance and extension and a high proportion of cell content in the dry matter. Tall fescue yielded well, but was low in proportion of cell content.