The unit is a greatly simplified screw expeller, modified so that the crop is thoroughly rubbed to liberate juice before the charge moves into the part of the unit in which pressure is applied. The throughput of the model described here is 2 kg of crop per minute; power consumption is about 400 W. The unit weighs 40 kg, but larger ones, operating on the same principles, could be made.

The development of two simple techniques, box storage and field clamps, which allow curing and storage of fresh cassava roots for 1 and 2 month periods, is described. Consistent and acceptable results have been obtained following storage of roots in boxes packed in moist but not wet sawdust and kept at ambient temperatures. The design of field clamps that maintain internal temperature below 40°C, to allow successful curing and storage, varies in different seasons. Storage life of roots is enhanced by the selection of roots in good condition, and any delay in placing the roots in storage results in poorer out-turns.

Effectively nodulated cowpea plants, grown in pots without applied nitrogen, were vegetatively equal to non-nodulated plants supplied with 60 ppm N throughout growth (88 days) and produced significantly greater seed yields. Supplying non-nodulated plants with 120 or 240 ppm N improved seed yields (but not significantly) compared with plants completely dependent on symbiotic fixation. Nodulation promoted branching, and improved pod set and/or retention compared with plants relying on applied N.

The efficiency of the Latin square design relative to the completely randomized and the randomized complete block designs is expressed in the form (A+BF) where F is a variance ratio (or the sum of two ratios). The constants A and B are evaluated, and lines showing relative efficiencies for given F values are drawn for the 5 × 5, 6 × 6, 7 × 7 and 8 × 8 Latin squares.

This paper reports results of a study to investigate the problem of introducing an improved technological package into the farming system in one area of northern Nigeria. It examines the economic and technical feasibility, as well as the social acceptability to the farmer, of growing sole cowpea given his environment and constraints. Studies of this nature are important as they provide insight into the problems farmers experience with improved technologies and thus represent one way of determining how to narrow the gap between yields farmers obtain and those obtainable at the research station level.

The effect of one, two or three applications of monocrotophos at 1120 g ai/ha at weekly intervals was determined on cowpea var. Ife Brown. All regimes were equally effective in grain production in early 1974 but spray applications 35 and 42 days after planting gave the best result in the late crop. Grain production from two applications was not significantly different from three applications in 1975. The control plots in the late season of both years failed, due to moisture stress and lack of pest control measures. It is considered that two sprays at flowering is adequate to forestall a crop failure in this variety.

In short clonal rows of sugarcane the mean weight of adjacent rows contributed significantly to the variance of row weight, mainly because some clones could increase their cane number at the expense of slow-tillering clones. Weight per cane and sugar content were unaffected by competition. Significant correlations were found between sugar content and (a) the rate of leaf appearance, (b) the ratio of fresh weight of leaf blade to fresh weight of joint, and (c) fibre as a percentage of cane fresh weight.

Experiments conducted on saline-sodic soils during 1972 and 1973 showed that delay in transplanting medium-duration dwarf high-yielding varieties like Jaya beyond 20 July caused substantial reductions in grain yield, but there was no depression in yield of such varieties even if 55 day old seedlings were used for transplanting at normal times. Older seedlings gave very high yields compared with younger counterparts at late transplantings. Fifty-five day old seedlings took about two weeks less to mature compared with ones planted when 25 days old.

An experiment is described in which the productivity of maize–bean and maize–potato mixtures in alternate rows was compared with pure stands of the component species in four cropping seasons. In seasons with low rainfall, yield from the mixtures fell short of that from pure stands, but in one exceptionally wet season a yield advantage was found for maize–bean mixtures. The poor performance of mixtures in low rainfall seasons appeared to result from large reductions in maize yield attributable to competition from the potato or bean. In the one high-rainfall season, no such reduction in maize yield occurred. An implication of these findings for farming systems with mixed cropping is discussed.

An experiment at the Kabete Field Station of the University of Nairobi compared maize–bean mixtures with pure stands of the two crops at three plant densities. Although the mixtures gave an apparent yield advantage over pure stands, this could be explained solely by the increased population pressure in the mixtures. The implication of this finding for other published work with cereal–legume mixtures is discussed, and a distinction is drawn between those sites in East Africa where a conclusive yield advantage from mixed cropping has been found and those where any apparent advantage might be explained by the higher population pressure.

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.