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.

Specific soil fertility and water retention constraints limit increased crop production in the subsistence-oriented farming systems of Burkina Faso. Previous attempts to introduce apparently promising technologies based on research that had not directly involved the fanner and that had not benefited from farmer-feedback have been largely unsuccessful. Active farmer involvement can help to identify relevant constraints to production and to identify and modify technologies to make them viable. Formal and informal farmer surveys and farmer participation in field experiments have led to the development of potentially useful cropping practices involving the complementary use of mechanical tied ridge and fertilizer-based technology.

The study was carried out in an unheated glasshouse under natural conditions of daylength and temperature. Rates of pod and seed growth and development, and of desiccation at maturity, are reported in single genotypes of Lupinus albus, Lupinus mutabilis, Vicia faba, Pisum sativum and Lathyrus latifolius. The histology of tissue layers in pods are also described. The culti-var of Pisum sativum completed dry weight accumulation in pods in 20 days from anthesis; the equivalent time in Lupinus albus (Kievskij mutant) was 60–70 days and in genotypes of Lupinus mutabilis and Vicia faba about 50 days. The heavier pods and seeds of the L. albus and V. faba cultivars were due to a prolonged rapid growth phase: rates of weight accumulation in seeds during the rapid growth phase were similar for all cultivars. The histology of the pod wall varied between species but the rate of dehydration of pods was not a factor in determining date of maturity. The results are discussed in the light of reservations based on known intra-specific variation in crop species.

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.

Two methods, namely combined plot analysis and integration of variograms, have been applied to investigate and compare plot-to-plot yields of intercropped millet (mean yield of about 1.9 t ha−1) and maize (mean yield 4.25 t ha−1) on terraces in Nepal. Combining plots diminishing the residual variance of millet from 0.52 (t/ha)2 of the original 1 m×1 m units to 0.08 (t/ha)2 for 4 m×4 m plots, the largest for which reliable estimates could be derived. The residual variance of maize declined from 4.91 (t/ha)2 of the original units to 0.61 (t/ha)2 for 4 m×4 m plots. Orientation was immaterial. The variogram for millet was isotropic and bounded with a range of approximately 4 m. Within-plot variance calculated from the variogram increased, and experimental error decreased, as the size of plots increased to this value, beyond which there was little gain. The variogram for maize was unbounded, and so gave no ‘natural' upper limit for plot size, that is, over the range studied, up to 6 m×6 m. It was also anisotropic with larger gradient in the direction from front to back of the terrace than along the contour. The reduction in residual variance was greatest for narrow plots elongated in this direction. Formulae are provided from which to calculate from the variogram approximate residual variances for experiments of given area and size, shape, and orientation of plots. Its application gave similar results to those from the combined plot analysis. Overall, the results from the two methods were consistent.

Field experiments were carried out during the rainy seasons of 1985 and 1986 to examine the frequency of weeding necessary for the optimum growth and yield of okra in Nigeria. Weed removal within 12 weeks of sowing generally resulted in significantly better crop growth and yield than that in the weedy check. Weeding once as early as four weeks was as beneficial to okra growth and yield as two or three weedings later in the 12 week period. Weed removal four times at 3, 6, 9 and 12 weeks significantly enhanced crop growth and pod yield over all other treatments. For good pod yields, protection from weed competition over most of the duration of crop growth is therefore essential. Such weed removal may enhance crop yield partly by increasing aeration and water movement in the soil.

Two bean genotypes differed in rate of root extension and elongation when grown under different soil water stresses in transparent tubes placed at an angle of 25°. Root intensity (the root length visible cm−2 of the viewing surface) gave a quick indication of the distribution of the total root length when screening cultivars for drought resistance.

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.

In spite of large year-to-year variations in clove yields, production in the islands of Zanzibar and Pemba is often in synchrony and the annual harvests of the two islands are correlated with similar variables. Clove harvests are positively correlated with rainfall in October to February two years before the harvest and negatively correlated with the harvest in the previous year and rainfall around July, and October to December of the year before the harvest. It is likely that rainfall in these periods affects vegetative growth of the clove tree and clove bud differentiation.

A common practice in some South American countries consists in moving around Capsicum chinense cultivars between regions where edaphoclimatic conditions differ notably. The purpose of this research was to compare and relate gas exchange responses with assimilate allocation patterns and flower and fruit production dynamics in a cultivar of C. chinense in three locations with different mean temperatures (19, 24 and 28 °C) along a gradient from 140–1855 m. Leaf gas exchange (leaf conductance, CO2 assimilation and transpiration rates) was measured at 60–70, 110–120 and 140–150 days after transplanting (dat) from seed beds. Dry weight per plant of leaves, stems and roots were determined at 50, 73, 96, 114 and 196 dat. Flowering dynamics and fruit production were followed weekly. A marked reduction (50%) in mean Gs was found at the site with the lowest mean temperature in relation to plants grown at the highest temperature site. Mean daily CO2 assimilation rate was higher for plants in the intermediate site and a reduction of 18 and 42% was found for sites with highest and lowest mean temperature, respectively. We report an adverse effect of low temperatures on growth of C. chinense. Flowering initiation and fruit production was delayed at lower temperatures. An increase in temperature (between 26–30 °C) led to an increase in the number of flowers; below this temperature it remained unchanged. Fruit production is drastically reduced at the lower temperature site due to a large number of aborted flowers and small fruits.

There is no one widely accepted method of managing international agricultural research and numerous different models exist. Here we review one in particular, referred to as the ‘institute without walls’, from the perspective of the UK Department for International Development's (DFID) Renewable Natural Resource (RNR) Research Strategy (1990–2006). We begin with a brief history of the RNR Research Strategy from 1990 to 2004. We then draw on nearly 15 years experience of managing one of the programmes within the RNR Research Strategy to assess critically the impact of externally and internally imposed organizational and management changes on the performance of the DFID Plant Sciences Programme (PSP). The current RNR Research Strategy (1995–2006), with its emphasis on demand-led research, has greatly increased the relevance and effectiveness of DFID's natural resources research. A comparison between the PSP in 2004 and the early 1990s inevitably concludes that the programme has been transformed: unlike in 1991, research is now firmly demand-driven, much is based in developing countries and farmers are benefiting from the research. Over time, the outputs of the long-term strategic research have been applied in practical plant breeding and participatory crop improvement programmes. Key to the success of the PSP has been the provision of continuous, long-term funding which has allowed projects time to develop and produce outputs of real value to end users. Alongside this, the ability of the PSP to build long-term, in-country partnerships has ensured the effective adoption of its research outputs. We conclude that the successes of the PSP have largely derived from (i) identification of research that is clearly demand driven, (ii) continuous long-term funding that has allowed research to move from the strategic to adaptive phase, (iii) continuity of management, and (iv) the flexibility to develop a wide range of partnerships, both in-country and overseas, based on their ability to deliver.

Larvae of bollworms (Helicoverpa armigera (Hubner), Earias sp., Diparopsis watersii (Rothschild) and Pectinophora gossypiella (Saunders)) feed on cotton flower buds (squares) and developing bolls causing severe yield losses. While endosulfan, an organochlorine insecticide was the most effective and widely used insecticide for bollworm control in Ghana, it has been banned due to abuse and hazard to the environment. Field experiments were conducted during the rainy seasons of 2012 and 2013 to determine the efficacy of foliar insecticides tihan (spirotetramat + flubendiamide), thunder (imidacloprid + betacyfluthrin), belt expert (flubendiamide +thiaclopride), dursban 4EC (chlorpyrifos-ethyl), lambda super 2.5EC (lambda cyhalothrin) and polytrin C (profenophos + cypermethrin) for control of bollworms and their impact on non-target beneficial organisms in Ghana. All the insecticides tested lowered bollworm densities and boll damage but applications of tihan or belt expert alternated with thunder resulted in the highest seed cotton yield. The treatments generally did not lower populations of predators such as ladybird beetles and lacewings and could be included in an integrated pest management programme for bollworms in cotton. These results suggest that alternate applications of tihan or belt expert with thunder can be recommended as a replacement for endosulfan for control of cotton bollworms and improvement of cotton yield in Ghana.

Native plantlets of Allium cepa (onion) were cultivated in selenium (Se)-supplemented soils to observe dose- and time-dependent uptake and associated pro/anti-oxidant activity. Allium plantlets were grown in soils supplemented with Se at 2.5, 5.0 and 7.5 mg kg−1 as selenite (Na2SeO3) and selenate (Na2SeO4) for 40–120 days. The effect of different concentrations of Se oxyanions on the growth and accumulation profile in plants in relation to glutathione peroxidase activity and thiobarbituric acid reactive substances was studied. Total Se concentrations in plantlets were determined by instrumental neutron activation analysis. The accumulation of Se in plant was observed to be dose dependent in the case of selenite, but, no definite correlation between accumulation levels and exposed concentration was observed. The changes in pro/anti-oxidant properties were observed to be dependent on the accumulation of Se in plant.

Supplementary irrigation experiments were conducted on a Clansthal sand and a Windermere clay. Irrigation treatments were based on the application of 1 inch of water when the soil moisture deficit reached 2·5, 3·5, 4·5 and 5·5 in. in 7 ft of soil on the sand, and 1·00, 1·75, 2·50 and 3·25 in. in 2 ft of soil on the clay. Each experiment included a dryland control and soil moisture was estimated weekly in each plot with a neutron probe. The results showed that there were significant linear increases in yield with increasing quantities of water applied. The crops exploited soil moisture to a depth of 6 ft in the sand and 3 ft in the clay, even with the maximum water treatments. Under dryland conditions, on the sand the crop exploited soil moisture to the wilting point only in the surface foot of soil, but on the clay the crop extracted moisture held at tensions greater than 15 bars in the top 3 ft of soil. The conclusions are that, where available water for supplementary irrigation is limited, heavy soils should be irrigated in preference to sandy soils, and that the most efficient use of both rainfall and irrigation water is achieved when 1 cusec is used to irrigate about 200 acres.

Limited moisture supply caused reduction in leaf area, number of effective tillers, ratio of sound to unsound grains and the nitrogen, phosphorus, iron and manganese content of rice. Crop yield was adversely affected in the absence of standing water. Two levels of nitrogen (40 and 60 kg.N/ha.) caused no significant difference in yield in 1965, but in 1966, when 30 and 60 kg. N/ha. were used, the latter gave better yields.

Seasonal fertilizer response of napier grass (Pennisetum purpureum) was measured on various soils in Brunei. Climate was moderately humid over the three-year experimental period, with the longest dry spell about 4 months. Optimal fertilizer N levels (balanced with other nutrients) ranged from about 240 to 900 kg/ha/yr on the different soil types and under different moisture conditions. Dry forage yields at the optimum fertilizer levels ranged from 5 t/ha/yr on sandy soil under dry conditions, to 55 t/ha/yr on a sandy clay loam with adequate water. Moderate production of about 20 t/ha/yr was obtained on acid sulphate soil with fertilizer and lime. Digestible nutrient and protein levels of 60-day forage were about 55 and 10% respectively.

Intercropping Brussels sprouts with cabbage was studied in two experiments comparing four different intercropping systems with sole crop production. Intercropping presented no agronomic or management problems because both crops had compatible cultural and crop protection requirements. Analysis of Land Equivalent Ratios and Relative Value Totals showed that the four intercropping systems gave consistently larger yields than the sole crops. In one experiment profitability, measured by the gross margin, was higher from all of the intercropping systems and costs per unit of produce were reduced. Similar results were obtained with one intercropping system in the other experiment. Alternative methods of evaluating the results in economic terms are discussed, together with the implications of intercropping in high-input systems of vegetable production.

Trials were made of the performance of batches of forage sorghum and maize, sown at different times of year. The optimum sowing periods of sorghum variety Abu Sabeen and maize variety 113 were found to be February to October and November to January respectively. Of the various climatic factors considered in this study, mean daily temperature was of greatest importance in affecting yield. The overall performance of sorghum was superior to that of maize, probably because of its relatively higher salt tolerance.

As a result of higher prices and improved marketing, cashew (Anacardium occidentale) farmers in Tanzania are trying to improve production through improved husbandry. The main production constraint is powdery mildew disease which causes large reductions in tree yields. Although fungicides can control this disease, the majority of farmers are unable to afford them. Recently, cashew material with some tolerance to the disease has been released to growers and use of this material will be one of the main ways for farmers to cope with the disease. Cashew is grown principally by smallholders in Tanzania and since 1993 ways for farmers to increase production by including improved material on their farms have been investigated in participatory trials. The most important initial step is to fell non-productive trees. Where there is sufficient space these can be replaced by improved material established either as grafted plants, polyclonal seed or by top-working. Improved material can also be planted in gaps amongst the trees.