Transient soil-moisture-deficit stress was imposed on groundnut (Arachis hypogaea) at three phenophases for different durations: long stress in the early vegetative phase (20 days after sowing); moderate stress in the early vegetative phase (20 days after sowing); stress at flowering (40 days after sowing); and stress at pod development (60 days after sowing). Stress was imposed for 30 or 25 days at the vegetative stage. Transient soil-moisture-deficit stress, at all phenophases, reduced the production of flowers. Soil-moisture-deficit stress for 25 days at the vegetative phase followed by two relief irrigations at an interval of 5 days, resulted in closely synchronized flowering. This factor contributed to a greater efficiency of conversion of flowers to pods and to higher pod yields. Total biomass accumulation was also higher in plants which experienced stress in the vegetative phase. Groundnut pod yields were increased by imposing a transient soil-moisture-deficit stress in the vegetative phase for 25 days, followed by two irrigations at an interval of 5 days. Thus stress in the vegetative phase was beneficial for groundnut growth and pod yields, but was highly detrimental when imposed at flowering and pod development.

Root development of maize (Zea mays), soyabean (Glycine max), cowpea (Vigna unguiculata), and pigeonpea (Cajanus cajan) was investigated with and without tillage. Observations were made at different growth stages by digging trenches normal to the rows, by core sampling, and by observing growth of roots against glass windows. There were more maize roots in the surface layer (0–10 cm) with no-tillage than in conventionally ploughed plots, but at 10–40 cm maize roots were more abundant and soyabean and pigeonpea roots less so in the no-tillage plots.

The traditional crops of Oceania are asexually propagated and are losing their positions in cropping systems because of their genetic vulnerability. This paper reviews genetic reasons explaining the deterioration of their agronomic performance, using information mostly derived from surveys of genetic resources conducted in more than 50 Pacific islands, coupled with genetic investigations. More than 2000 cultivars have been analysed for isozyme variation. Cultivars and wild forms showed greater isozymic variation in Melanesia than in Polynesia and Micronesia but the genetic base for many of these crops was much narrower than morphological and chemical variation had suggested. No correlations were found between zymotypes, chemotypes, and morphotypes. Cultivars exhibited variation in qualitative traits as a result of human selection of somatic mutations. Accumulation of viral particles in propagules and build-up of pest and pathogen populations are often responsible for poor agronomic performance. If breeding of these traditional crops is to have any future, it is important to exchange genotypes to broaden the base of existing programmes.

The effects of site and rate of application of fertilizer on the grain and straw production of barley were investigated in 75 trials on representative farmers' fields. Grain and straw production were strongly but curvilinearly correlated with growth-period rainfall over the range 136–568 mm, almost irrespective of soil type, previous crop or fertilizer rate, and responded positively to applied nitrogen and/or phosphorus in 74 of the trials. Responses to nitrogen increased and those to phosphorus decreased with increasing rainfall. Yields tended to be lower but responses to nitrogen were higher where barley followed barley and were influenced by the availability of phosphate and mineral nitrogen in the soil at planting time.

These results are summarized in regression equations, which express yield quadratically in terms of fertilizer rates, seasonal rainfall and their interactions over the full 75-trial data set and within representative sub-sets. The wide differences in crop response to fertilizer highlight the problem of recommending fertilizer rates for a low and variable rainfall environment. Simple second-order multiple regressions for different geographical areas, rainfall zones, crop rotations etc., based on mean rainfall values, account for around 40% of the variance in yield response to nitrogen and phosphorus fertilizer; only a small proportion of the remaining variance appears attributable to rainfall variability. Alternatively, yield may be expressed as a function of fertilizer rate and rainfall using rainfall probability values derived from long-term records. This can be used to estimate the probabilities of predetermined yield responses for specified sites and fertilizer rates and to produce maps of those probabilities.

A field experiment was conducted to evaluate the comparative effectiveness of poultry manure, urea N and the integrated use of both in changing soil properties, nutrient uptake, yield and yield attributes of maize grown at Rawalakot, Azad Jammu and Kashmir, Pakistan. Treatments include control without any amendment (N0); urea N (UN) = 120 kg N ha−1 (N120U); UN = 150 kg N ha−1(N150U); poultry manure (PM) = 120 kg N ha−1(N120PM); PM = 150 kg N ha−1(N150PM); UN = 90 kg N ha−1+ PM = 30 kg N ha−1(N90U+30PM); UN = 60 kg N ha−1+ PM = 60 kg N ha−1(N60U+60PM); UN = 30 kg N ha−1+ PM = 90 kg N ha−1(N30U+90PM). N fertilization from different sources and combinations increased dry matter yield from 5206 kg ha−1 in the control to 5605–5783 kg ha−1 and grain yield increased from 1911 kg ha−1 to 2065–3763 kg ha−1. Application of the highest rate of urea N recorded the highest grain yields of 3763 kg ha−1, double the control. The proportional increase for N90U+30PM and N60U+60PM was 85 and 83% while PM alone gave lower yields (41 and 44%) than the respective urea N treatments. Integrated use of urea + PM proved superior to other treatments in enhancing the uptake of N, P and K in plants. Averaged across two years, uptake of N, P and K in N90U+30PM and N60U+60PM was 88 and 85, 16.5 and 17.5, and 48.5 and 53.5 kg ha−1, respectively compared to 52.5, 11.5 and 33.5 kg ha−1 in the control. Nitrogen use efficiency (NUE) varied from 29% in PM treatments to 30–39% in combined treatments while NUE of 40% was recorded for urea N treatments. Application of PM lowered soil bulk density from 1.19 t m−3 in the control to 1.10 and 1.05 t m−3 in N120PM and N150U, enhanced pH from 7.39 to 7.65 and 7.78 and increased soil organic matter (22 and 32%), total N (21 and 26%), available P (44 and 55%) and available K (10 and 15%) compared with the control. Economic analysis suggested the use of 50% recommended mineral N (60 kg N ha−1) with PM saves the mineral N fertilizer by almost 50% compared to a system with only mineral N application. In addition, increase in N efficiency, plant nutrition and soil fertility associated with combined treatment would help to minimize the use of high cost synthetic mineral fertilizers and represents an environmentally and agronomically sound management strategy.

The on-farm evaluation of three feeding strategies for smallholder campesino dairy herds was undertaken in the highlands of Central Mexico with cooperating farmers: traditional, alternative and intermediate feeding strategies. All three incorporated grazing of cultivated pastures, but concentrate use was 4.0 and 7.0 kg per cow per day in the rainy and dry seasons respectively for the traditional feeding strategy, 3.3 for the alternative feeding strategy in both rainy and dry seasons and 5.0 and 9.0 kg per cow per day in the rainy and dry seasons respectively for the intermediate feeding strategy. Feeding during the dry season was based on maize straw in the traditional strategy, on pasture complemented with maize silage in the alternative feeding strategy, and with some maize silage but mostly maize straw in the intermediate feeding strategy. The trial ran between 25 September 1996 and 24 September 1997, divided by season into four, thirteen-week periods. Milk yields were recorded once per week, and live weight and body-condition score, every 28 days. Three cows per strategy that completed each period were blocked according to stage of lactation and used for the statistical analysis of a split-plot design with feeding strategies as main plots and weeks as split-plots. Overall mean milk yields were 15.5±2.05, 13.4±2.43 and 12.4±2.37 kg milk per cow per day for alternative, intermediate and traditional feeding strategies respectively, with significant interactions (P<0.05) for autumn, winter and summer. The alternative feeding strategy (with over 50% less concentrate) produced milk yields 0.24 and 0.38 higher than the intermediate and traditional feeding strategies in the dry season. In the rainy season, milk yields with the alternative feeding strategy (30% less concentrates) were 0.09 and 0.16 higher than the other two strategies. Margins per day of family labour were: alternative feeding strategy US$36.48 per day, intermediate feeding strategy US$9.22 per day and the traditional feeding strategy US$9.11 per day, although in the case of the last two there were two family members in charge of the dairy herds. Results demonstrate the successful integration of grazed pasture and maize silage for the efficient production of milk, and provide evidence on the productive use of limited campesino land resources in the face of unviable economic conditions for maize grain production.

Breeding for high and stable yields is a major objective for cassava breeding programmes. Owing to the simultaneous formation of steins and leaves (source) and storage roots (sink), competition for assimilates implies that there is an optimum leaf area index for yield. This has led to the use of the harvest index as a practical criterion for selection. The optimal harvest index and leaf area index are discussed for selection for stressful environments. A successful strategy for developing high yielding varieties for favourable conditions is presented. Recent information has shown that selection for a slightly larger than optimal leaf area index, and hence greater biomass, can lead to stable yield in both favourable and stressful environments. Moreover, yield levels can be increased by selecting for moderate harvest indices (e.g. 0.5-0.65) and increased biomass. Longer leaf life is an integral part of this selection strategy. These concepts are discussed in detail.

James H. Cock y Mabrouk A. El-Sharkawy: Caracteristicas fisiológicas para la selección de la mandioca.

Two sets of on-farm trials, each covering two years, were conducted in the northern Guinea savannah of Nigeria over the period 1999–2001, the objective being to compare integrated Striga hermonthica control measures (soybean or cowpea trap crops followed by maize resistant to Striga) with farmers' traditional cereal-based cropping systems. In both sets of trials, this proved to be highly effective in increasing productivity over the two year period, especially where soybean was used as a trap crop. Resistant maize after a trap crop increased the net benefit over the two cropping seasons in both trials by over 100% over farmer practice. However, in the second set of trials there was no significant increase in productivity between a trap crop followed by Striga resistant maize, and a trap crop followed by local maize especially where legume intercropping and fertilizer had been applied in the farmer practice. There was also no increase in productivity between two years' traditional cereal cropping and one year's local maize followed by Striga resistant maize. This indicates the importance of a legume trap crop in the first year in order to ensure high productivity in the second year, regardless of variety. Up to 20% of farmers obtained higher productivity from their own practices, notably intercropping of cereals with legumes and use of inorganic fertilizers. Leguminous trap crops and Striga resistant maize, together with two key management practices (increased soybean planting density and hand-roguing) were seen to be spreading both within and beyond the research villages, indicating that farmers see the economic benefits of controlling Striga. Survey findings show that explaining the reasons why control practices work can greatly increase the adoption of these practices. Wider adoption of Striga control will therefore require an extension approach that provides this training as well as encouraging farmers to experiment and adapt Striga control options for their local farming systems.

Straws and stovers are often called ‘by-products’ of grain production even though they are increasingly important, e.g. for animal feed, thatching, soil improvement, mushroom production and industrial use. As a result, plant breeders, agronomists, economists and animal nutritionists have to pay more attention than before to the total value of crops, i.e. whole plant value in which straws and grain both play a part. This paper reviews literature about the technical potential of breeding and/or management for more or better straw. It then discusses issues of the economic value (EV) and nutritional value (NV) of straw and stovers for livestock feed to guide research and development in cereal breeding and management. It is mainly based on experiences from the Indian subcontinent and semi-arid regions of the Near and Middle East. The paper shows that the quantity and quality of straw produced has changed considerably over recent decades as a result of breeding policies, new cultivation patterns and choice of cultivars. Both EV and NV depend on type of grain, animal production system and access to other feeds. A classification of these factors is provided and suggests that the EV of straw is particularly important in low-input systems with stovers from coarse grains.

In a 2 row cereal: 1 row pigeonpea intercropping system, four sorghum and two millet genotypes were examined with four of pigeonpea on a medium-deep Alfisol during 1978 and 1979. The cereals usually produced a large proportion of their sole crop yields. Millets matured relatively early which allowed large yields of later-maturing pigeonpea. A tall millet gave the best total Land Equivalent Ratio (LER) of 1.78 and most monetary returns. Early and/or short sorghums produced large LERs (1.51–1.59) and combinations with an early hybrid also gave good returns. A tall late sorghum gave poor yields of both components, smallest total LER (1.30), and little return. Pigeonpea intercrop yields became larger as the maturity difference between the cereal and pigeonpea increased. A combination of a short, early but large-yielding cereal with a pigeonpea that is as late as possible without incurring undue risk of moisture stress may be ideal.

Rainfed wheat is frequently exposed to periods of water stress that generate low and variable grain yields. Field experiments (with studies in Tunisia and Morocco) carried out in the context of a European research project of co-operation with Mediterranean partner countries (WatNitMED) showed that nitrogen (N) fertilization may be a tool to increase productivity of rainfed wheat in Mediterranean environments. However, most farmers in Northern Africa do not fertilize their rainfed cereals. In the present study, we aimed to analyse whether the generally accepted positive yield response to N fertilization in rainfed Mediterranean conditions corresponds to actual advantages achieved in the fields of working farmers, attempting a further up-scaling of knowledge from field experiments to real fields. We attempted to apply research results to Tunisian working farmers’ fields by conducting a farm pilot experiment. The pilot experiment was conducted in two different regions (a low-yielding region and a relatively high-yielding region) of cereal production in Tunisia, where wheat production represents typical rainfed Mediterranean agro-ecosystems in North Africa. First, we compared the yield response to N fertilization against unfertilized conditions (a common situation for many of the farmers in North Africa), and secondly we compared what the farmers suggested as an optimal N fertilization practice in their fields against the WatNitMED's recommendation which was based on an N-fertilization scheme derived from field experiments from the European research project in Mediterranean conditions. The WatNitMED fertilization scheme suggested higher rates of fertilization than those considered optimal by farmers (on average 40 kg N ha−1 higher). Unfertilized grain yield across both locations ranged from about 1 to 3.5 Mg ha−1 (typical of farmers’ yields in the region), and fertilizing increased grain yields in most situations. Within the two alternative fertilization treatments, WatNitMED fertilization produced higher yields than the fertilization rate considered optimal by farmers. This trend was observed at the low-yielding location as well as at the high-yielding location. These responses demonstrated that fertilization in working farmers’ field conditions may be a reliable means of improving dryland wheat grain and straw yields. They also showed that rates of fertilization regarded as optimal by real farmers were below the optimum for these regions.

Seedling growth in the nursery and the magnitude of shock experienced by the seedlings after transplanting can affect subsequent growth and development of transplanted rice (Oryza sativa). These two processes have not been adequately represented by rice growth simulation models. In this study, seedling growth in the nursery was described with respect to endosperm mobilization, dry matter (DM) distribution and seed size. In addition, the transplanting shock process was represented describing the crop development and growth in relation to seedling age at transplanting. These relationships, as two sub-models, were incorporated into CERES-Rice, a rice growth model, and their performances compared with independent field data. The nursery growth sub-model was also evaluated with another model, RIBHAB. Results of the comparison showed that the nursery growth sub-model, either with CERES-Rice or RIBHAB, closely predicted observed seedling growth. On the other hand, CERES-Rice overestimated root and leaf DM and underestimated culm DM, while RIBHAB underestimated all the growth traits considered in the evaluation. Transplanting shock period predicted by the sub-model closely mimicked observation, whereas CERES-Rice highly overestimated it. It is concluded that the developed nursery growth and transplanting shock sub-models can be incorporated into CERES-Rice and other rice growth models for better simulation of those growth processes.

Sorghum (Sorghum bicolor (L.) Moench) is a major staple crop of Burkina Faso where farmers continue to cultivate photoperiod-sensitive guinea landraces as part of the strategy to minimize risk and ensure yield stability. In the Boucle du Mouhoun region, however, sorghum farmers appear to have insufficient varietal choice due to cropping systems having shifted towards more intensive cultivation of cotton and maize, and rainfall patterns having decreased over the past decade. In search for new varietal options that can respond to this changing context, researchers decided to give farmers access to ex-situ national collections along with the opportunity to evaluate recent improved varieties. From 2002 to 2007, researchers and farmers worked closely together to implement on-farm testing, including varietal selection trials, crop management and multi-locational trials. Farmers’ choices tend to differ among groups, villages and years, with the exception of four particular landraces: two originating from a collection carried out in the Mouhoun region more than 30 years previous to this research, and two other landraces that came from the dissimilar agro-ecological zones of Burkina Faso. These four were the most commonly selected landraces out of 36 cultivars that covered both improved and landrace varieties. Farmers’ selection criteria were focused on adaptation to agro-climatic conditions as well as specific grain qualities for processing and consumption. The potential usefulness of each variety was verified via multi-locational trials. The paper also shows that wide dissemination of experimental seed, not just across the Mouhoun region but also at a national scale, was largely achieved through collaboration with a strong farmer organisation in conjunction with farmer training programs focused on the on-farm seed production and the commercialisation of this seed.

Rice is the major staple food crop in the North Eastern Region of India (26.2 million hectare geographical area) and the region has a deficit of 1.40 million tones of rice, mainly due to low productivity (1.72 t ha−1). Field experiments were conducted for the first time to evaluate the new techniques of rice cultivation, viz. the system of rice intensification (SRI) and integrated crop management (ICM) along with conventional rice culture (CRC) for improving productivity, water and energy use efficiency during the rainy seasons of 2004–07 at the ICAR Research Complex for North Eastern Hill Region, Umiam, Meghalaya (950 m msl), India. Three stand establishment methods, viz. SRI, ICM and CRC in main plots, and five nutrient management practices, viz. recommended dose of fertilizers (RDF = 80:26:33 kg NPK ha−1), farmyard manure (FYM) 10 t ha−1, RDF + FYM 5 t ha−1, 50% RDF + FYM 10 t ha−1, and a control (no fertilizer and manure) in sub-plots, were tested in a split-plot design; only few meaningful interactions were found. Results showed a higher number of panicles per square metre under CRC and ICM compared with SRI. However, the number of panicles per hill, grains per panicle and the test weight remained higher in the SRI method. In terms of mean grain yield, ICM (4.86 t ha−1) and SRI (4.72 t ha) produced 12.8 and 9.6%, respectively, higher grain yield over CRC (4.3 t ha−1). Among the nutrient management practices, the application of RDF + FYM 5 t ha−1 (5.0 t ha−1) and 50% RDF + FYM 10 t ha−1 (4.87 t ha−1) not only produced higher grain yield of rice (23.8 and 20.5%, respectively, higher yield over control) but also maintained higher soil available N, P and organic carbon at harvest compared with other nutrient management practices. Photosynthesis rate and water use efficiency were found to be significantly (p < 0.05) higher under SRI, whereas the transpiration rate was higher under CRC. The ICM method recorded maximum net return and energy output to input ratio, which was followed by SRI and CRC. Therefore, the ICM method of rice cultivation would be the preferred option for the sub-tropical mid-hills of eastern Indian Himalayas.

This paper addresses the preservation and use of minor root crop genetic resources, mostly aroids and yams. Conservation is fraught with difficulty: ex situ collections are expensive to maintain and methods for on-farm conservation have not been studied. Conventional breeding strategies present serious limitations when applied to these species. Furthermore, the evaluation and distribution of improved material are as problematical as its conservation. The similarities shared by these species regarding their domestication, breeding constraints and improvement strategies as well as farmers' needs, are briefly reviewed. Based on these biological constraints, we propose a practical alternative to current conservation and breeding strategies. This approach focuses on the geographical distribution of allelic diversity rather than localized ex situ and/or in situ preservation of genotypes. The practical steps are described and discussed. First, a core sample representing the useful diversity of the species is assembled from accessions selected for their diverse and distant geographic origins, wide genetic distances, quality, agronomic performances and functional sexuality. Second, the geographical distribution of this core sample, in vitro via a transit centre, allows the direct use of selected genotypes by farmers or for breeding purposes. Third, the distribution of genes is realized in the form of clones resulting from segregating progenies and, fourth, farmers select clones with local adaptation.

The objective of the research was to test whether safflower (Carthamus tinctorius) could be grown successfully and profitably as a rain-fed, winter, oil-seed crop at a high-elevation site in a semi-arid area. A three-year field experiment was conducted in the Bekaa Valley of Lebanon at a site 995 m asl with a mean annual precipitation of 518 mm. Two safflower lines, Syrian Hama Local and PI301055, selected from earlier screenings, were compared with barley and lentil, the two dominant rain-fed crops, together with chickpea. Safflower flowered and matured more than a month later than the other three crops, and gave the highest dry matter at flowering. Safflower yielded more than chickpea and lentil, and there were no significant differences in yields between the safflower lines and barley, which is the highest yielding winter crop in semi-arid northern Bekaa. The straw yield of safflower was higher than that of barley, which was in turn higher than those of chickpea and lentil. According to calculations based on seed yield, safflower gave the highest net revenue of $191 ha−1, followed by lentils ($160 ha−1), chickpea ($97 ha−1), and then barley ($27 ha−1). Farmers in the semi-arid Bekaa Valley of Lebanon and in other areas with similar conditions are recommended to plant safflower to meet a regional vegetable oil deficit and to diversify cropping systems.

A long-term trial with Leucaena leucocephala was initiated in 1982 to test the sustainability of Leucaena-based alley farming compared to a conventional cropping system without trees and with continuous cultivation of maize. It assessed the integration of short grazed fallows in rotation within Leucaena alleys and their effect on soil fertility and crop yields.

The various treatments had no effect on soil pH during the four-year period of the trial. The organic carbon and total nitrogen contents of the soils under conventional cropping were lower by the end of the fourth year than those under alley cropping and alley grazing treatments, whereas soil phosphorus levels were lower in the alley cropping and grazing plots. Foliage dry matter production of Leucaena under alley cropping management ranged from 6.0 to 6.7 t ha−1 a−1 under continuous cropping and reached 8 t ha−1 when alley cropping was preceded by a grazed fallow. Crop yields were consistently higher with alley cropping than with conventional cropping. Alley cropping plots in rotation with two year grazed fallows gave significantly higher crop yields during cropping years than those under continuous cultivation.

Concentration of tea yields in Malawi into regular successive peaks within the main growing season is the cause of severe economic problems. A model of the causes of these peaks has been developed and its explanatory power is confirmed in the light of empirical tests of its component parts and predictions. A computer version of the model is presented and its predictive power demonstrated. Use of the model to explore relations between weather and yields is discussed, with indications of its limitations for this purpose.

Potassium application appeared to increase dry matter production and yield of oil palms, primarily by increasing leaf area, while nitrogen increased both leaf area and net assimilation rate. Responses to phosphorus and magnesium were harder to interpret. Production of vegetative dry matter attained a fairly constant level at the higher rates of fertilizer application, while the ratio of bunch yield to total dry matter production was little affected by fertilizer treatments. The importance of these results for oil palm breeding, and their possible value in diagnosing fertilizer requirements, are briefly discussed.

The yields of eight grass species, Axonopus compressus, Brachiaria decumbens, B. humidicola, B. miliiformis, Dicanthium caricosum, Ischaemum aristatum, Paspalum conjugatum and Stenotaphrum secundatum, were compared at five sites under different coconut densities giving variations in shade. Light transmission (LT) values were approximimately 100 (adjacent open area), 70, 50, 40 and 20% of full sunlight. Soils were fertile, red-brown clays developed on uplifted coral limestone (typic arguidoll), with marginal K status. Brachiaria spp. yielded most in full sunlight, with B. decumbens giving 28 t ha−1 year−1. I. aristatum was less sensitive to shade than the Brachiaria spp., at least down to 40% LT. S. secundatum, although poor yielding at 100 and 70% LT, gave the best yield of all species at 20% LT. Shaded plants had thinner leaves and larger nitrogen concentrations than unshaded ones. B. decumbens and B. humidicola are recommended for open plantations (LT > 70%), I. aristatum for moderate shade (LT 45–70%) and S. secundatum for deeper shade (30–50%) on poor fertility soils.