Advanced genotypes of common bean (Phaseolus vulgaris L.) were tested on-station and on-farm to evaluate their performance and acceptability under farmers' circumstances. Farmers were given seed of the genotypes to plant a minimum area of 100 m2 to be grown as a sole crop or intercropped with sorghum according to their preference. Yield, seed colour, taste, maturity time, disease reaction, growth habit and many other bean characteristics were assessed by farmers. The promising genotypes were higher yielding than the farmers' genotypes in most testing sites. Pairwise ranking of the genotypes showed that in export-oriented western Hararghe, white pea bean (navy bean) type Awash-1 and food bean G-2816 were preferred. In eastern Hararghe GLP ×92 and G-2816 were highly preferred but white pea beans were not preferred. Genotypes in advanced observation nurseries were also evaluated by the farmers and some of the genotypes have been promoted for further testing in yield trials. Selection criteria have been proposed by the farmers in each region. Future breeding and selection of genotypes will incorporate the proposed selection criteria and priorities of the two regions.

The area under hybrid maize cultivation is increasing rapidly across South Asia. However, information regarding the proper nutrient management for modern stay-green maize hybrids in India is not adequate resulting in low productivity. Existing nutrient management practices are not able to capture the momentum change in the scenario of soil nutrient supply capacity and plant nutrient demand for achieving higher yield target. The present study aims at establishing the site-specific nutrient management (SSNM) package for an inceptisol (West Bengal, India). Soil indigenous nutrient supply capacity and nutrient use efficiency was also evaluated by using the nutrient omission plot technique. The experiment was laid out in strip-plot design, assigning three maize hybrids (P 3522, P 3396 and Rajkumar) in the vertical strip and nine fertilizer treatments [50% RDF/Recommended dose of fertilizer, 75% RDF, 100% RDF (200-60-60 kg N-P2O5-K2O ha−1), 125% RDF, 150% RDF, 100% PK, 100% NK, 100% NP and control (zero-NPK)] in the horizontal strip, with three replications. Results of the experiment revealed that the differences among cultivars were generally non-significant. The maize hybrids showed greater yield response to fertilization with N (4.14 Mg ha−1) during winter, followed by K (2.54 Mg ha−1) and P (1.58 Mg ha−1). Indigenous nutrient supply was estimated 107.2, 37.6 and 107.7 kg ha−1 for N, P and K, respectively. Both average agronomic efficiency (AE) and recovery efficiency (RE) were increased with 50% RDF and it decreased with further increase in NPK levels up to 150% RDF. The average internal efficiency (IE) was higher with 50% RDF closely followed by the treatment with absence of N. As grain yields and gross return over fertilizer (GRF) under 75 to 150% NPK treatments were similar, nutrient doses of 150 kg N, 45 kg P2O5 and 45 kg K2O ha−1 were recommended as optimum for maize hybrids.

Since the Green Revolution, the public-sector's agricultural research strategy for increasing food crop productivity has been explicitly based on the premise that technology can cross political and agro-climatic boundaries, primarily through the ‘training and visit’ system of extension (also known as ‘transfer of technology’ and the ‘pipeline’ model). Today, a different strategy is emerging. Efforts to develop the necessary institutional capacity for more client-oriented participatory research, particularly in plant breeding, are now a central part of the public-sector agricultural research strategy. Greater use of participatory and gender-analysis approaches in agricultural research has significant conceptual and methodological implications for impact assessment and institutional learning.

Soil acidity, incipient potassium deficiency, and a deficiency of one or more trace elements were limiting factors in three trials of long-term soil fertility changes under continuous cultivation in the Sudan Savanna zone of Nigeria. The effectiveness of organic manures is explained largely or wholly in terms of these factors, since no evidence has yet been found to suggest that the addition of organic matter as such is of value.

The effect of boron nutrition on the susceptibility of young tenera oil palm seedlings to red spider mite attack was studied. Highest concentrations of mites were recorded in seedlings which had received little or no boron in the growing media. Injuries by mites were greatest when the leaves had the highest number of mites per unit area, the lowest boron concentration and the lowest concentration of cyanidin.

The performance of promising genotypes of faba bean developed for areas with limited rainfall was compared with the local landrace, ILB 1814, at Tel Hadya in Syria during 1989–1988 using different row spacings and sowing densities. In the last two years of the trials the performance of the improved genotypes and ILB 1814 was compared with and without supplemental irrigation. Yields of ILB 1814 were better than the highest yielding genotypes in some years and similar to them in others. In seasons with limited rainfall the best yields were obtained by using a narrow row spacing and dense sowing, and yields were significantly improved by irrigation. Grain yield was correlated with biomass and the number of pods per unit area. The percentage of radiation intercepted was highest in ILB 1814, particularly when sown with a narrow row spacing and at a high plant density. Soil water extraction, evapotranspiration and water use efficiency were improved by sowing at a narrowrow spacing and high plant density.

Los nemátodos de las plantas y la agricultura continua

Field experiments were conducted for 3 years covering 4 crop seasons at Lucknow to study the utility of pigeonpea (Cajanus cajan) as an intercrop in economizing N for maize (Zea mays) and to assess the residual fertility of kharif crops on autumn-planted sugarcane (Saccharum officinarum). Pigeonpea increased the soil N content due to substantial nodulation, but as an intercrop it did not increase the yield of maize at any level of nitrogen. Sugarcane grown after pigeonpea yielded 43% more than when grown after maize. Intercropping pigeonpea in maize would be more beneficial than growing a pure crop of maize before planting sugarcane.

Mesquite (Prosopis spp) is a nitrogen-fixing and drought-resistant leguminous tree which exists in many of the semi-arid regions of the world but little has been done to develop its potential for wood, nitrogen fixation or pod yield. We report field and greenhouse cultural practices for mesquite and the results of a field screening trial for biomass production of 32 accessions, representing North and South American and African germplasm. Non-destructive biomass estimates, derived from height and stem diameter measurements, had a 180-fold range; the preponderance of slow-growing accessions were from the rangelands of southwestern USA.

In most cotton-growing regions of West and Central Africa where rainfed conditions prevail, cropping conditions are highly diversified since the crop is planted over an extended period. We studied production and development patterns in 10 cotton (Gossypium hirsutum) varieties to determine the most efficient strategies that could be transformed into breeding traits. Four trials were carried out between 2002 and 2003 in two cotton-growing areas in Benin to compare the 10 varieties at three stand densities and two planting dates. The parameters monitored were the mean first flower opening date (FF), effective flowering time (EFT), plant height at harvest (HH), height to node ratio (HNR), length of fruiting branch (LFB), number of vegetative branches (NVB) and average boll retention at the first position of the fruiting branches (RP1). We identified two ideotypes that yielded better than the others: (i) Mar 88-214 performed well under late planting–high stand density conditions and was characterized by low vegetative growth and early flowering onset, a short flowering period and low RP1; (ii) H 279-1 performed especially well under early planting–low stand density conditions and was characterized by high vegetative growth, late flowering, long EFT and high RP1. We propose a breeding strategy for both ideotypes based on seven indicators with high heritability (FF, HH, HNR, and LFB) or medium heritability (NVB, EFT, and RP1).

Three cultivars of Coffea arabica, Catuaí Vermelho IAC 81, Icatu Amarelo IAC 2944 and Obatã IAC 1669–20, were evaluated in relation to leaf gas exchange and potential photochemical efficiency of photosystem II under field conditions on clear and cloudy days in the wet season in southeast Brazil. Independent of levels of irradiance, leaf water potential (υleaf) values were always higher than the minimum required to affect daily net photosynthesis (PN). PN, stomatal conductance (gs), leaf transpiration (E) and the index of photochemical efficiency (Fv/Fm) declined on a clear day in all cultivars. The depression of leaf gas exchange and Fv/Fm (specially around midday) caused a strong decrease (about 70 %) in daily carbon gain on a clear day. Under cloudless conditions, gs and PN were correlated with the air vapour pressure deficit (VPDair), but not with photosynthetic photon flux density (PPFD) values. On a cloudy day, the daily carbon gain was barely limited by PPFD below 800 μmol m−2 s−1, the Fv/Fm values showed a slight decrease around midday, and gs and PN were positively correlated with PPFD but not with VPDair. By contrast, irrespective of the contrasting irradiance conditions during the day, PN and E were correlated with gs.

The shoots of high, medium and low yielding clones of tapioca were examined to see whether yield was associated with morphological characteristics of the foliage and/or with leaf area development. The lowest yielding variety had the highest leaf area per stem, and vice versa, differences in leaf area being mainly due to differences in leaf size. Leaves of the highest yielding variety possessed attenuated lobes, which tended to have a more vertical mid-day orientation, whereas the lowest yielding variety possessed large broad-lobed leaves with more horizontal orientation. The intermediate variety had acutely attenuated lobes and showed a much more vertical day-time orientation. The relationship between the leaf properties and canopy efficiency is discussed.

Changes in growth rate of tea shoots cause yield fluctuations between seasons, but the size of the basal shoot population remains constant throughout the year. The proportion of shoots with dormant apical buds does not influence the mean weight of shoots harvested. Models of shoot extension are discussed.

Chickpea production in marginal (<600 mm annual rainfall) areas of the northern cropping region in eastern Australia is considered to be constrained by low rainfall, soils with low plant available water capacity (PAWC), subsoil salinity, low plant stature and poor fruit set. This study examines these constraints to assess the magnitude of their impact and if agronomic practices can improve potential production. Over three years a total of 42 commercial chickpea crops were monitored following a participatory action research approach focusing on perceived production constraints. Subsoil salinity significantly reduced PAWC for chickpea compared to wheat. However, PAWC for chickpeas from the majority of sites monitored was comparable to other areas. The supply of water between flowering and maturity was significantly related to yield. The agronomic practice of levelling following deep planting improved the lowest pod height by 10 cm and plant stresses experienced during flowering caused a 50 % loss of potential fruit. Constraints impacting on the supply and storage of soil water could be minimized by selecting paddocks with low chloride levels in the upper layers and sowing crops when the available soil water is greater than 100 mm. Reducing fruit loss at flowering has the potential to improve yields significantly. The mechanisms behind this loss were not identified but are worthy of further research.

A maize-breeding programme was targeted at resource-poor farmers of eastern India using a client-oriented approach (often called participatory plant breeding). Farmers tested a range of varieties in a participatory varietal selection programme but none proved to be very popular. Information from these trials was used in a breeding programme to develop a broadly-based population from three yellow- and three white-grained maize varieties that were either identified in the trials or had traits liked by farmers. The population was subjected to several cycles of random mating. In the C3, C4 and C6 cycles, subpopulations were extracted and subjected to mass selection over several generations in environments that represented well the target population of environments of resource-poor farmers' fields in eastern India for traits identified by farmers. To identify better the required traits, in some generations the selection was carried out by farmers on a research farm under fertility levels that approximated farmers' practice. The improvement of the subpopulations resulted in several varieties that performed well in research station and on-farm trials. One of them, BVM 2, was released in Jharkhand state, India. In multilocational research station trials, it yielded more than the control variety BM 1 but silked earlier. In the less favourable environments of on-farm trials, its yield superiority, in percentage terms, was higher. Farmers perceived BVM 2 to have better grain quality and stover yield than the local varieties. BVM 2 was specifically bred to meet the needs of the clients (resource-poor farmers with no access to irrigation) and has earlier maturity combined with higher grain yield. The returns were higher from this highly client-oriented approach, than by classical breeding, mainly because uptake was faster as a result of research and extension being done in tandem.

Canavalia ensiformis, Crotalaria grahamiana, Dolichos lablab, Mucuna pruriens, Tephrosia vogellii and Tithonia diversifolia were evaluated as potential species for soil fertility replenishment in on-farm adaptive trials, farm visits and field days in Tororo District, eastern Uganda. Farmers used multiple criteria for assessing and selecting those species that fitted within their production systems and production objectives. Farmers also adapted the technologies to allow for local opportunities and constraints. A preference ranking and logit regression analysis of probabilities of acceptance of the species conducted in 19 farmer groups showed that Mucuna had high, Tithonia and Crotalaria intermediate, and Canavalia, Lablab and Tephrosia low probabilities of being accepted or adopted. The evaluations showed that whilst technologies need to be adapted, a single-use technology had little chance of large-scale adoption. This paper highlights adaptations/innovations by farmers, and opportunities for participatory action research targeting farmers' production objectives.

In contrast to earlier results, a clear advantage from mixed cropping of maize and beans (Phaseolus vulgaris) was found in the long-rain seasons (March to September) of 1976 and 1977. Pure stand yields were low due to drought in 1976 and excessive rainfall in 1977. These and other results for long-rain seasons in Kenya suggest that mixtures are more efficient where pure stand yield levels are low, but there is little difference between cropping systems where levels are high. Light interception by maize leaves was quite small until late in the life of the bean crop.

The percentage dry matter of some Nigerian vegetables increases with age. Corchorus olibrius gave the highest yield of vitamin C after five weeks, but the stage of maturity had less effect with other vegetables. The oxalic acid content of Celosea argentea was very high, approaching a lethal level. It appears that some of the vegetables are best at about six weeks from sowing from the standpoint of eating quality, oxalic acid and vitamin C content.

Simple linear correlations, stepwise multiple regressions and path-coefficient analyses were used to determine the relation between grain yield of maize (Zea mays L.) and weather factors in a three year study involving several planting dates within each year. Maximum and minimum relative humidity, which demonstrated negative relationships with yield, were the most reliable factors, both directly and indirectly, for predicting yield. Temperature (including accumulated heat units), sunshine hours and total and effective rainfall generally showed negligible direct effects on yield. Potential evaporation, which showed positive correlation, had a negative direct influence on grain yield. We conclude that, whenever possible, path analysis should be used as well as correlation and regression analyses in explaining the complex multiple interactions of yield and weather factors in crop production.

Three pearl millet and three cowpea genotypes were examined in intercropping systems on deep sandy soils in Niger between 1984 and 1987. The intercropped pearl millet genotypes usually produced at least 80% of their sole crop yields when the cowpea was planted two or more weeks after the pearl millet. The early maturing and spreading cowpea genotype contributed most to LER. All cowpea genotypes yielded more when planted in association with dwarf rather than the traditional tall pearl millet genotypes because they received more light.

The low yield of pearl millet largely due to the low adoption of improved varieties substantiates the application of client-oriented plant breeding for pearl millet. Hence to enhance adoption, new varieties must correspond to farmers’ preferences and respond to the constraints prevailing in the production environments, participatory rural appraisals were conducted in two agro-ecological zones (Sahel and North-Sudan) to determine farmers’ preferences in the choice of varieties and to identify constraints to pearl millet production. The study revealed that the major production constraints are hierarchically drought, Striga, head miner, bird and downy mildew. Compact panicle, large grain size and non-bristle panicle were the most preferred traits in pearl millet across agro-ecological zones. Very long panicle and early maturity crop cycle were more preferred in the Sahel zone whereas, in the North-Sudan zone medium panicle length and medium maturity cycle were more preferred by farmers. Traits largely rejected by farmers were small grain size, narrow, loose and bristled panicle. Very few investigations were done to understand the raison of the low adoption of improved technologies in pearl millet. This study identified the major criteria of new pearl millet variety adoption by farmers. It is expected that breeding program must integrate these criteria in new pearl millet variety profiling to enhance adoption.