In order to identify factors that constrain or favour adoption of five crop or forage related and six animal husbandry technologies promoted by government to small-scale dairy farmers, a field survey was conducted with 115 farmers. A binary logistic regression model was fitted to identify socioeconomic and farm variables explaining the technology adoption. Factors that favoured technology adoption were based on perceived usefulness, productivity and benefits to the farm, farmer's skills and farm characteristics; moreover farmers were more willing to use technologies which required low levels of investment such as de-worming, vaccines, and data recording. Constraints were related to economic restrictions, lack of knowledge, lack of land, herd size, lack of extension advice, lack of information about government programmes, requirements associated with applying for government financial support, and technologies considered to be of little or no importance to the farm such as herbicides, artificial insemination (AI) and milking machines. Adoption of crop or forage related and animal husbandry technologies was significantly associated (p < 0.05) with socioeconomic (farmer's education, farmer's experience, farmer's wealth status) and farm characteristics (herd size, cows in production, milk yield, total hectares and technological level). It is concluded that the approach implemented in this study enables identification of key factors together with the communication approaches that have been successful.

By comparing flowered and non-flowered plants of the same age (where flowering was inhibited by photoperiod control), cane yield gains due to prevention of flowering were estimated to be 56·6% in a plant crop and 33·8% in a ratoon crop. Sugar gain due to prevention of flowering was 69·1% in the plant and 35·4% in the ratoon crop. A simple negative linear relation was found between cane (and sugar) yield per plant and the proportion of canes that flowered. There was no significant difference in fibre content of flowered and non-flowered canes. The influence of loss of growth, side-shoot production and pithiness on the yield of flowered canes are discussed.

Pot and field investigations were conducted to study the effects of vesicular-arbuscular mycorrhizal (VAM) inoculation and triple superphosphate fertilization on nodulation, dry matter yield and tissue nitrogen and phosphorus contents of Bradyrhizobium-inoculated soya-bean and lablab bean in the Sudan.

Inoculation of both crops with the VAM fungus Glomus mosseae in clay and sandy soils in pots increased nodulation, dry matter yield and tissue nitrogen and phosphorus contents more than triple superphosphate fertilizer, but even greater responses were obtained from G. mosseae combined with fertilizer. Crop responses in the two soils were similar, despite the large differences in soil physico-chemical properties.

In the field, inoculation of both crops with any of four VAM fungi enhanced nodulation, dry matter yield and plant nitrogen and phosphorus contents more than did triple superphosphate. Gigaspora margarita and Glomus mosseae were superior to Gigaspora calospora and Acaulospora species and resulted in more extensive root infection, especially in soyabean.

Experimental data on tillage requirement of cocoyam (Xanthosoma sagittifolium) are needed to identify the most suitable tillage methods for managing the fragile Alfisols of the humid tropics to ensure sustained productivity. Hence, five tillage methods were compared as to their effects on soil physical and chemical properties, and growth and yield of cocoyam on an Alfisol at Owo in the forest-savanna transition zone of southwest Nigeria. The experiment consisted of five tillage methods: manual clearing (MC), manual ridging (MR), manual mounding (MM), ploughing + harrowing (P + H) and ploughing + harrowing twice (P + 2 H) were used for three years at two sites in a randomized complete block design with three replications. In the first two years (2007 and 2008), P + H produced the least soil bulk density and highest growth and yield, whereas in the third year (2009), MC produced the lowest soil bulk density and best performance of cocoyam. Manual clearing produced the best values of soil chemical properties in 2008 and 2009. Averaged over the three years, P + H, MR and MM had lower soil bulk density hence better growth and yield compared with P + 2 H and MC. Over the three years MC, MM, MR and P + H increased cocoyam cormel yield by 10, 21, 23 and 32%, respectively, over P + 2 H.The corresponding increases in corm yield were 7, 15, 13 and 21%, respectively. The multiple regressions revealed that bulk density and moisture content significantly influenced the yield of cocoyam. Soil chemical properties were not significant. Bulk density rather than soil chemical properties dictated the performance of cocoyam in an Alfisol of southwest Nigeria. Soil quality was degraded by P + 2H. For small farms, either MR or MM is recommended while P + H is recommended for large-scale farming of cocoyam.

Fertilization of rubber plantations has been poorly documented despite the huge economic and ecological impact of this tropical perennial crop, especially in Southeast Asia. The main objective of this paper is to provide information on the fertilization practices of rubber smallholders in Thailand and to investigate the drivers of these practices. Data were sourced from individual interviews conducted with 414 rubber smallholders. The results showed that 99.4% of the mature rubber plantations were fertilized with either chemical or organic fertilizers, or both. The average dose of chemical fertilizers was 105/53/92 kg ha−1 of N/P/K that is consistent with the national recommendations. We estimated that almost two-thirds of the plantations had intensive or very intensive fertilization practices. Geographical location, especially the distinction between historical and new rubber-producing areas, appeared as a major factor explaining differences in fertilization practices. Several drivers commonly found in the literature did not affect the fertilization practices of the rubber farmers, highlighting some specificity of perennial crops and a context where access to fertilizer was not an issue. The high economic and environmental costs of intensive fertilization practices, while their benefit to the yield of rubber plantations continues to be debated, show the need to conduct research on sustainable fertilization practices in rubber smallholdings.

Nodule and plant dry weight of five photoperiodically different cowpea varieties increased with increasing day-length. There were no effective nodules on any varieties in 8-hour days and the response of nodulation to day-length was greater than plant dry weight. Nodule and plant dry weight also increased with increasing availability of water, but at the highest watering rate nodule weight was significantly lower under long than short days. Cowpea should nodulate well under tropical day-lengths provided enough water is available.

The economics of coffee plantations is intrinsically linked to pruning, which can improve the canopy architecture and thereby increase productivity. However, recommended pruning times on conilon coffee plantations have been made on an entirely empirical basis. In this study, by evaluating growth, photosynthetic gas exchanges, starch accumulation and crop productivity, the effects of pruning at different times between harvest and flowering were investigated for six conilon coffee clones with distinct stages of fruit maturation (early, intermediate and late). Clones with an early maturation stage were pruned at four different times: 0, 30, 60 and 90 days after harvest (DAH). Intermediate clones were pruned at 0, 30 and 60 DAH, and late clones were pruned at 0 and 30 DAH. Overall, the rates of shoot growth and net photosynthesis, the stomatal conductance and the crop yield were not affected by the pruning treatments in any of the clones. In addition, pruning times did not affect the concentrations of starch or the photochemical efficiency of photosystem II. The carbon isotope composition ratio was marginally affected by the treatments. These results suggest that the pruning time after harvests is relatively unimportant and pruning operations can be scheduled to optimise the use of labour, which directly impacts the production costs of coffee.

Extra-short-duration pigeonpea (Cajanus cajan) genotypes generally yielded more than short-season legumes when sown at the normal time on rainfed medium-deep Alfisols. However, their growth and yield were more reduced by delayed sowings and varied more widely between seasons than those of the short-season legumes, especially cowpea and black gram. All the crops gave lower yields on shallow Alfisols than on medium-deep Alfisols and none was consistently superior. Partitioning of dry matter into grain yield was less affected by time of sowing, soil and season in extra-short-duration pigeonpea genotypes than in short-season legumes. Less sensitivity of biomass accumulation to various abiotic constraints is therefore a major objective in improving the adaptation of extra-short-duration pigeonpea genotypes.

Cajanus cajan de duración extra-corta

During a period of dry weather, seedling tea bushes were generally less stressed than the clones which had been derived from those plants by vegetative propagation. There were interesting differences between the clones in their responses to dry conditions, but these could not have been predicted from similar observations made on the heterogeneous seedlings. However, it should be possible to use tests, based on measurements of the xylem water potential and stomatal resistance, to identify potentially drought-resistant clones at a later stage in the selection programme.

Experiments were carried out to relate soil moisture to leaf water potential (Ψ1), and to determine the effects of varying Ψ1, on leaf conductances and photosynthesis in coffee. Stomatal conductance was maximum at 0900 h, but plants growing in drier soil showed marked mid-day stomatal closure. After 1500 h, stomata began closing although plant water status improved. Photosynthesis in relation to changing Ψ1 appeared to exhibit roughly three different rates. At the fixed experimental temperature (25°C) low Ψ1 reduced photosynthesis throughits influence on stomata, but under field conditions low Ψ1 and an accompanying rise in temperature could lower the rate by lowering both mesophyll and stomatal conductances.

Principal component analysis is a mathematical technique for summarizing a set of related measurements as a set of derived variates, frequently fewer in number, which are definable as independent linear functions of the original measurements. Consideration of their mathematical nature shows that they do not, themselves, necessarily correspond to sensible biological concepts, though they are more amenable to statistical study than the original measurements. Further, by assessing the extent to which they are in accordance with biological hypotheses, or with the results of other, similar, analyses, they can be transformed into other linear functions which are meaningful in the biological sense, or consistent with other results. Thus the specific technique of principal component analysis is developed into a more general component analysis approach. With proper regard for the purpose the analysis is intended to serve and for the mathematical restrictions involved, this approach can lead to a useful condensation of a mass of data, a better under-standing of the observed individuals as entities rather than collections of isolated measurements, and to the formulation of new hypotheses for subsequent examination.

The soil health of rubber (Hevea brasiliensis) plantations shows a declining trend, mainly due to the continuous mono crop cultivation and the ‘clean-weeding’ practices. Another weeding approach which allows the under-flora to grow profusely after closing up of the rubber canopy (no-weeding) can establish a multi-flora system that can improve soil health. A case study was undertaken to test this hypothesis. Rubber fields with and without control of under-flora were investigated for different soil properties, biomass and nutrients of under-flora and rubber yield. The ‘no-weeding’ practice for about 10 years in the rubber fields significantly improved the soil OC, N, available forms K and Mg, respiration rate and moisture status. The biomass and associated nutrients of under-flora also were much higher while the rubber yield was not negatively affected in the ‘no-weeding’ fields. The new weed management system is of great significance in improving soil quality, carbon sequestration and biodiversity conservation, besides the economic and energy savings without affecting crop yield.

The small amount of on-farm research that has been carried out with fodder trees in Africa has mainly involved exotic species selected by researchers rather than farmers. In this study, farmers who had participated in a pre-planting survey chose, during feedback meetings, seedlings of indigenous, naturalized and some exotic fodder trees from a nursery. They planted them on-farm, where the planting niches, management, biomass production, and animal response were evaluated over a short period, and compared with the results of the earlier survey. The farmers came from three agro-ecological zones in central Kenya with respective mean annual rainfall totals of 775, 950 and 1300 mm. Data were collected at two months, one year and two years after planting. The feedback meetings proved important to the understanding of discrepancies between the earlier survey results and farmers' practices. Survival and growth of seedlings, manure application by farmers, and percentage of trees pruned for fodder, differed among species. The farmers showed a strong interest in experimenting with and actively cultivating local fodder trees.

Papaya has never been found in the wild, but is believed to have originated in tropical America from where it has spread throughout the tropics and subtropics. This fruit crop is particularly important in India and Brazil. Most research on the water relations of papaya has been undertaken in Brazil and on the island of Guam (United States of America). Papaya is a short-lived large herb, growing to a height of up to 10 m. Leaves emerge from the upper part of the unbranched stem. After a juvenile period, lasting for about two months, flowers begin to develop in leaf axils. Flowering continues throughout the year as new leaves emerge. The plants, which are dioecious, begin to bear fruit within a year after planting, sustaining high yields for two years before yields decline. The ‘effective’ root depth varies with the method of irrigation, but can reach 0.55 m. The seedlings and the trees are susceptible to wind damage, a topic that has been well researched. Stomata are only found on the abaxial leaf surface. They are sensitive to changes in the saturation deficit of the air. Stomata also respond quickly to changing light conditions. On clear days, midday suppression of photosynthesis occurs as a result of partial closure of the stomata. In the morning, there is a time lag between water loss by transpiration and sap flow, as water is taken from storage in the hollow stem. Few attempts have been made to measure the actual water use of papaya, and there are no reliable published values for the crop coefficient. Limitations to the design of the papaya irrigation experiments reported so far make it difficult to reconcile the results in practical ways. Water productivities equivalent to 1.8 to 2.8 kg (fresh fruit) m−3 (irrigation water) have been obtained. Although papaya is generally considered to be drought sensitive and responsive to irrigation, there is a shortage of good experimental evidence to support this view. There is a need to establish practical irrigation schedules for this remarkable crop. A uniformity of approach to irrigation experimentation and a common, universally agreed nomenclature would facilitate this process.

An experiment to determine weed spectrum, weed seedling numbers, temperature and nutrient changes in manure heaped for one to five months was undertaken over two seasons. Weed seedling numbers in manure heaped for one to five months decreased significa ntly by 65–70%. The weed spectrum comprised 17 broadleaf weed species of which Amaranthus hybridus, Leucasmartinicensis and Nicandra physalodes were most prevalent. There were six grasses with Eleusine indica and Cynodon dactylon being dominant. Temperature increased from 20 °C in the unheaped manure to averages of 34 and 42 °C in manure heaped for three and five months respectively in the two seasons. In both season s nitrogen and potassium became more available as the period of manure heaping increased while phosphorus decreased. It was concluded that heaping manure for three months significantly reduces weed seed viability and enhances the availability of some nutr ients.

The effects of drought and plant density on fractional interception (f), radiation-use efficiency (RUE) and dry matter accumulation and partitioning to seeds in cowpea (Vigna unguiculata) need to be quantified in order to calibrate cowpea simulation models for West Africa. Accordingly, a short duration cultivar of cowpea, IT84S-2246-4, was grown at a range of plant densities in well-watered and drought conditions in 1990–91 at two contrasting locations in Nigeria, Ibadan (7°N) and Kano (12°N). Fractional interception of radiation (f) and total above-ground dry matter accumulation (TDM) were measured throughout the growing season and TDM and seed yield (SY) were measured at maturity. At Ibadan drought had no effect on phenology while at Kano drought increased the duration of the vegetative phase (by 5–6 days), but not of the reproductive phase. Drought reduced f and radiation-use efficiency (RUE), and hence TDM, and there were significant interactions between RUE and plant density at both Kano and Ibadan. Average SY in the well-watered treatments at Kano and Ibadan were 1600 and 700 kg ha⊃−1&/sup; respectively and drought reduced SY by 50% at both sites but did not interact with plant density. Across locations, plant densities and drought treatments SY was strongly correlated (r = 0.96) with TDM production between flowering and maturity. These data suggest that partitioning of dry matter during the reproductive phase is not affected by location, drought or plant density and the SY of cowpea can be predicted from dry matter accumulation.

Application of S, alone or in combination with P, significantly increased the number, yield and nitrogen content of root nodules on pigeon pea and guar. Sulphur, applied at different levels with NPK, increased the methionine content and yield of plants significantly but had no significant effect on the N content. Sulphur at 20 p.p.m., alone or in combination with P, increased the methionine content of pigeon pea significantly but the effect decreased at higher levels of S. In general, higher values of methionine were obtained in the presence of S than when it was absent.

The general principles of leaf analysis as a diagnostic method and as a guide to plant nutritional status are outlined and discussed. Factors, other than nutrient supply, that affect leaf composition are mentioned and methods of leaf sampling, preparation and storage are described. The practical application of leaf analysis to fruit, flower, vegetable, tree and miscellaneous economic crops is reviewed and suggestions are made for its use as an advisory aid.

A continuous non-limiting soil water supply, or a non-limiting supply from 120 to 180 days after planting, significantly increased (P = 0.01) female flower production of banana cv Robusta compared with continuous soil water stress. Relieving stress after 120 days produced a significantly higher (P = 0.05) average number of female flowers per inflorescence than when adequate water was supplied throughout. Female flower production is positively correlated with the average growth rates at floral initiation and early floral differentiation and with the final pseudostem girth.

The effect was investigated of seasonal differences between winter and spring on the development of parthenocarpic and fertilized fruits in two squash cultivars, Zucchini Elite F1 and Bushy White. The former had stronger parthenocarpic characteristics than the latter. The effect of night temperature on growth of the parthenocarpic fruits was most pronounced, both rate of growth and final weight increasing with decreasing temperature. Whereas long days inhibited development of parthenocarpic fruits, the heaviest and longest fruits were obtained under normal day-length conditions.