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.

Water scarcity due to global warming can increase the water demand for upland rice at critical stages of crop development. However, there is little research on cultivar responses to this scenario and technologies that enhance water use efficiency (WUE). To determine the influence of water stress at and after flowering stages of drip-irrigated upland rice cultivars on physiology, yield, and WUE, a shelter experiment was conducted using a randomized block design with a split-plot arrangement of treatments. Three modern and one traditional cultivar were subjected to five irrigation managements: 100% of the field capacity considered the reference management (RM), 70 and 40% of the RM at the flowering stage, and 70 and 40% of the RM at the grain-filling stage. In general, the modern cultivars tended to maintain higher photosynthetic rate, stomatal conductance, transpiration, leaf water potential, and lower crop water stress index compared to the traditional cultivar under water stress. The WUE decreased for all cultivars under severe stress, averaging 0.55 and 0.62 kg m−3 when stress occurred at flowering and grain-filling, respectively, whereas moderate stress imposed at grain-filling maintained WUE for all cultivars, averaging 1.21 kg m−3. In addition, grain yield (GY) showed a similar variation trend under drought stress as WUE, and its reduction was mainly associated with low filled grain percentage. Among the five irrigation treatments, both GY and WUE were the highest in the RM; the best cultivar recorded 9.3 Mg ha−1 and 1.62 kg m−3, respectively. Findings suggest that attending to the full water demand under precision drip irrigation and appropriate cultivar selection can enhance upland rice production at significant levels.

Pera sweet orange (Citrus sinensis L. Osbeck) is the most important mid-season sweet orange cultivar in Brazil, not only because of its desirable fruit quality for both juice processing and the fresh fruit market, but also because there is a lack of adequate mid-season alternative sweet orange cultivars. This study aimed to evaluate the horticultural performance of other sweet oranges in an attempt to identify similar or superior selections to the standard cultivar, Pera IAC sweet orange. Seventeen sweet oranges selections, including the standard Pera IAC, were budded on Sunki mandarin [C. sunki (Hayata) hort. ex Tanaka]. The experiment was planted in 2007, using 12-month-old nursery trees, with 6.5 × 2.5 m spacing in the Southern region of São Paulo state, Brazil. The experimental orchard was maintained with standard commercial management practices, and without supplementary irrigation. Data collection started three years after planting and was carried out until seven years after the experiment had been installed. Vegetative growth, plant yield, fruit drop, fruit quality, and fruit maturation regressions were assessed. Averages of the alternative selections were compared with those of the standard cultivar by Dunnett test. Performance indexes were calculated in order to identify potential superior selections for the fresh fruit market and for juice processing. Results indicated significant differences among the selections evaluated when compared with the standard cultivar, suggesting better alternatives to be exploited. Five selections (Biondo, Finike, Pera Alexandre Maróstica, Seleta Rio, and Vaccaro Blood) offered superior performance in terms of attributes required for the fresh fruit market, while one selection (Pera Alexandre Maróstica) was superior for juice processing traits. These alternatives to Pera IAC represent an opportunity for more efficient and productive scions with higher fruit quality, and with a slight shift within the mid-season harvest time of sweet oranges in Brazil.

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.

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.

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.

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.

The auxin-transport-inhibiting morphactin chlorflurenolmethylester (CFM; Methyl 2-chloro-9-hydroxyfluorene-9-carboxylate) breaks the dormancy of axillary buds in young coffee plants and produces orthotropic shoots. A concentration of CFM as low as 50 mg/litre induced an average of 24 orthotropic shoots per 6-month-old seedling. This approach could provide a fast and inexpensive method of vegetative propagation for raising disease-resistant cultivars if adult clones respond similarly to the seedlings used here and the treatment does not adversely affect the propagation of induced shoots.

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.

In mountainous areas of Continental South East Asia, double cropping in the irrigable valleys and terraces is often promoted as a way to increase farmers’ income while alleviating the pressure of agriculture on fragile slopes. However, cold temperature and low global radiation may constrain this strategy. Lethally cold events may occur, and increases in crop cycle length may jeopardize the correct timing of the main rice crop, taking place in summer. The model PYE (potential yield estimator) simulating the impact of temperature and radiation on the development and yield of annual crops was adapted to account for the range of temperature occurring in the area under study. It was calibrated against experimental data for the three crops that are most often considered as spring crops in the irrigable land of the northern mountains of Vietnam: rice, soybean and maize. Then a virtual experiment was designed in order to simulate various scenarios combining crop species and sowing date with climatic data accounting for variability of climate across years, location and elevation. Completed with a sensitivity analysis, it allowed to define favourable ‘sowing windows’ for non-water limited environments, based on the three following criteria: high average yield, low incidence over years of lethally cold events and low incidence over years of delays in the maturity of the spring crop. The length of this sowing window varied greatly across the scenarios tested. The widest was obtained for the case of soybean whatever the location and elevation, which makes it the less risky of the tested options. The approach followed proved effective to identify favourable and unfavourable environments in order to help better targeting the policy in support to the introduction of a spring crop in the mountains of Vietnam.

Agronomic techniques to even out the intra-seasonal fluctuations in yields of tea in Malawi are described, and evidence presented of their effects on the level and distribution of yield. Such treatments reduce yields per acre, but by overcoming constraints on capacity they may lead to increased yields for the estate as a whole. The full benefit of some of these practices requires the prediction of yield patterns based on current and expected weather. Several techniques can be combined to form a flexible approach adapted to each particular year, but more work is required to quantify the parameters and functional relations involved before alternative strategies can be properly compared.

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.

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.

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.

Three species of lupin, three vetches and a soyabean were evaluated as green manures under tropical highland conditions. With moderate soil fertility and 150 days of rain, all lupin types and a locally obtained vetch gave yields of about 80 t ha−1 fresh material. Under less favourable conditions, low soil pH and high aluminium saturation, only Lupinus luteus achieved these yields. During the short season, with about 60 days of rain, the yield of L. luteus was reduced to 30 t ha−1 and establishment of the vetches was slow and they yielded poorly. Growth of soyabean was poor under cool conditions. Under fertile conditions, lupin grain yields of up to 5.2 t ha−1 were obtained in the long season but in the short season, yields were less than 1 t ha−1. Rhizoctonia solani was the major disease encountered.