Although the groundnut and soyabean are not close taxonomic relatives they have a number of features in common. Both are polyploid (2n = 4x = 40 chromosomes) and have arisen from the domestication of wild polyploids. Polyploidy has occurred independently at least twice in the genus Arachis, while in Glycine the genus includes both tetraploids and octoploids, an unusually high ploidy level in a legume. Both crops are oilseeds although oil content varies widely between the two species, ±50% in groundnut and ±20% in the soyabean. The soyabean produces ±35% protein content of good quality whereas that of the groundnut is ±30% and less well balanced nutritionally. The soyabean originated in the Far East whereas the groundnut originated in the eastern Andes foothills (N.W. Argentina to S. Bolivia). The evolutionary changes under domestication in the soyabean are typical; the cultigen has become a compact, erect, self-supporting plant with reduced pod dehiscence and loss of seed dormancy. The evolutionary response pattern of the groundnut is similar but modified on account of its geocarpy. This necessitates the maintenance of adequate contact between basal branches of the plant and the soil for effective fruiting. Notwithstanding this, strongly ascending growth forms have become established. The greatest contrast between the two species is in photoperiod sensitivity; the groundnut is day-neutral while the soyabean is a short-day plant with genotypes varying widely in the day length tolerated without inhibition of flowering.

Four plant densities and two genotypes of potato intercropped with sugarcane were examined at Lucknow, India and compared with potato–sugarcane sequential cropping. The best yields and monetary returns were obtained with one sugarcane row to two rows of potato (Kufri Chandramukhi) at 80 × 103 potato plants ha−1; this treatment combination gave virtually a full yield of both potato and cane. Sequential cropping of potato and sugarcane with 80 × 103 potato plants ha−1 in rows 50 cm apart gave better yields than intercropping potato with sugarcane in a 1:1 row arrangement. Kufri Chandramukhi, a short duration variety of potato, was more suitable for intercropping with sugarcane than the long duration Kufri Sindhuri. Growing potato either in sequence or as an intercrop with sugarcane decreased soil bulk density and increased its available nitrogen content.

The effects of iron pyrites, organic materials and micronutrients on the yield of rice and wheat and on the amelioration of saline sodic soil were studied at Kanpur. The grain yield of the first crop of rice increased from 1.37 to 2.97 t ha−1 following application of pyrites at 50% of the estimated gypsum requirement. The grain yield of succeeding wheat and rice crops also increased significantly with pyrites treatment. These increases were associated with marked decreases in pH, electrical conductivity, exchangeable and soluble sodium content and bulk density of the soil and with an increase in its hydraulic conductivity. The beneficial effect of pyrites was increased with the application of rice straw, Sesbania as green manure and micronutrients, the pyrites plus Sesbania green manure treatment being the most effective.

Apparatus was built to screen sorghum and pearl millet for seedling emergence through a hot soil surface. Seeds were sown in soil in long clay pots arranged in a steel water tank so that the top 7 cm of the pots was above the water level. The soil in the pots was heated with infra-red lamps fitted to a frame above the tank. By adjusting the height of the frame the temperature of the soil could be changed. The system allows emerging plumules to be subjected to high soil temperatures (up to 50°C) but without water stress. Both crops exhibited genotypic differences in emergence.

The capacity of sorghum lines to germinate at high soil temperatures (above 40°C) is clearly related to the temperature sensitivity of embryo protein synthesis. The development and optimization of a simple laboratory technique based on this correlation for the rapid large-scale screening of sorghum lines is described. Embryo-containing half seeds are incubated in the presence of 14C-labelled amino acids at different temperatures and the resulting radio-labelled proteins extracted and bound to nitrocellulose discs for counting. The extent to which incorporation of 14C-label into proteins is inhibited by elevated temperatures can be used to predict the likely temperature sensitivity of a given line during germination.

The information collected from an experiment on tea, in which two plucking intervals and three plucking standards were imposed, allowed analysis of the effects on the total value of output (Cloughley et al., 1983; Cloughley, 1983). The analysis can be extended and its practical relevance improved by incorporating harvesting and manufacturing costs. Using information collected in another experiment and readily available economic information the effects of incorporating these costs are presented. A method of simultaneously determining optimal plucking interval and standard is described.

Two extensions to the Land Equivalent Ratio (LER) concept, the Effective LER and the Staple LER, are evaluated for an intercrop of two species. The use of different standardizing sole-crop yields in the Effective LER equation is emphasized for the formation of different comparisons between intercrop and sole-crop yields. The Staple LER for different standardizing sole-crop yields is introduced. The equivalence of the Staple and Effective LERs under certain conditions is shown and illustrated.

The vertical distribution of water potentials within the leaf canopy, along the stem and within the soil profile of a winter wheat crop was analysed and it is concluded the failure by previous workers to recognize the significance of petiolar resistance has probably resulted in over-estimates of the resistance of the soil to water uptake by root systems of field crops.

From an analysis of the water relations of several winter wheat crops an equation is developed to describe the extraction of soil water reserves by crop root systems, based upon values of soil water potential, root xylem potential and ‘effective’ resistance to water uptake which can be obtained from field experiments. The equation provides an empirical basis to specify the minimum desirable root system for efficient capture of soil water reserves, to analyse the effects of differing root distributions and thus to help identify situations where it would be profitable to modify rooting either by tillage or by plant breeding.

Field trials designed to investigate the effects of nitrogen, phosphorus and potassium on the yield, starch and dry matter content of white guinea yam were conducted over a four year period in south western Nigeria. The optimum level of nitrogen for successful production of white guinea yam was 35 kg ha−1 in a forest Alfisol that had been under cultivation for at least two years. Nitrogen, phosphorus and potassium had no significant effect on starch content, but large applications of phosphorus and potassium significantly decreased dry matter accumulation.

Under rainfed conditions in north west India, intercropping with soyabean, peanut, greengram and clusterbean reduced sunflower yields by 25–50%. The number of pods per plant and grain yield of the leguminous intercrops were also reduced. The maximum LER (1.05) was obtained from the sunflower–greengram mixture. Intercropping increased the protein percentage of the sunflower but decreased that of the companion legumes. It had no effect on percentage oil content of sunflower.

A field study was conducted on vertisols to determine the effect of three watering regimes and two plant densities on growth and yield of groundnuts. Total water requirements ranged from 486 to 597 mm depending on treatments. Three quarters of the water depletion was from the upper 20–30 cm. Plants in the sparse population were more sensitive to water stress so that the watering interval could be lengthened in the dense population without seriously reducing yield.