In the process of developing an improved fallow system based on forage legumes, the potential interest of crop-livestock farmers in enhancing soil fertility restoration and dry-season feed supply was assessed during a socio-economic study on 11 farms of settled agro-pastoralists in the subhumid zone of West Africa. Simultaneously, eight farmers in the group participated in simple and largely farmer-managed on-farm experiments testing the establishment of selected forage legumes on fallow land. In addition to agronomic parameters, the participatory approach included an evaluation of the technology by farmers both during farm visits and field days.

With cropping and dry-season feeding strategies increasingly being limited by land availability, the agronomic performance of some of the tested legume species, in particular Stylosanthes guianensis, promised substantial productivity gains once they could be integrated into the traditional fallow system. The major concerns of the farmers were animal health and labour supply for cropping activities, rather than soil fertility and feed constraints. The need for initial weed control within most of the legume species, therefore, limited their acceptability by farmers at this early stage of innovation testing. Nevertheless, farmers' interest grew remarkably in the course of the study. Options for the selection of appropriate species and management practices, which aimed at facilitating the establishment of legumes on fallow land, are discussed as a means of enhancing further adoption of the innovation.

The effects of levels of soil moisture and plant population on lodging and associated losses from mechanical harvesting of two lentil genotypes, one susceptible and one resistant to lodging, were investigated during 1986–87 and 1987–88 at Tel Hadya in northern Syria. High plant population increased lodging because the crowded plants had thin stems, while high levels of soil moisture caused lodging because biological yield was increased. When biological yields were high a two tonne increase in biological yield led to a one point increase in lodging score. Mechanical harvesting increased losses in biological yield due to lodging by 12% compared with yields obtained by hand harvesting under rainfed conditions and by 24% at the highest level ofsoil moisture. It is suggested that supplementary irrigation should be used in dry seasons in trials to select genotypes resistant to lodging.

Decaimiento de la lenteja

A farm survey conducted in Ethiopia in 1986 identified seasonal food shortage as an important problem facing farmers. The researchers proposed the development of an early maturing maize variety to alleviate the problem and by 1988, on-farm trials of a selected variety were initiated. About two-thirds of the farmers retained part of the harvested crop as seed for planting, indicating their strong interest in the variety. Farmer-designed trials were found to be especially effective for obtaining farmers' assessment of the new variety and for monitoring how they incorporated it into the farming system.

Maíl con maduración temprana para Etiopía

Information on the influence of date of planting on protein, oil and fatty acid composition of soybean seeds is meagre, whilst similar studies on lipoxygenase isozymes and trypsin inhibitor contents are lacking. A field experiment was conducted with nine Indian genotypes and three planting dates (spread over 23 days) to study the influence of planting dates on these seed traits. Results based upon a one-year study indicated that oil content declined with delays in planting. Oleic acid content increased from the first to third planting, while the reverse trend was observed for linolenic acid. Lipoxygenase-1 activity was reduced by delayed plantings. Protein content was the lowest and trypsin inhibitor content was the highest for the second planting. However, no differences were observed for protein and trypsin inhibitor contents between the first and third planting. Significant interactions. observed between genotype and planting date for most of the seed compositional characters suggest that the influence of late planting is genotype-dependent.

Gene flow from herbicide-resistant rice (Oryza sativa L.) cultivars can affect the biodiversity of Oryza spp. and can result in the lack of opportunity to control weedy rice through selective herbicides. The aim of the present study was to quantify the outcrossing rate from the herbicide-resistant red rice and rice cultivars carrying three different ALS (acetolactate synthase) alleles using a single plant pollen donor approach. A field experiment was performed using the encircle population combination technique. The main plots comprised the pollen-receptor IRGA 417 cultivar or a susceptible biotype of weedy rice, and the subplots comprised the pollen-donor inbred cultivars IRGA 422 CL and PUITÁ INTA CL, the hybrid SATOR CL or a resistant biotype of weedy rice. Among the pollen-donors, the outcrossing rate for pollen receptor susceptible weedy rice and the IRGA 417 cultivar was 0.0344% and 0.0142%, respectively. Rice cultivars carrying the ALS gene mutations Ala122Thr, Ser653Asn and Gly654Asn showed a similar outcrossing rate of 0.0243%. The outcrossing rate decreased over a distance of up to 3.5 m from the pollen-donor and was not affected by the wind cardinal direction. The risk of gene flow of herbicide resistance from rice to weedy rice should be reduced through the development of new strategies to contain and mitigate gene flow and of the elimination of weedy rice escapees.

Despite interest in mucuna (Mucuna pruriens) as a green manure/cover crop, biomass production of its accessions has been poorly quantified, including in the Los Tuxtlas region of Veracruz, Mexico where smallholders have used maize (Zea mays)-mucuna systems increasingly since 1991. This on-farm research compared the biomass production of three mucuna varieties (white-, mottled-, and black seeded) in a rotational maize-mucuna system. Mucuna was sole-cropped during the first season (on eleven and five fields in 1996 and 1997 respectively), and its impact on the second-season maize yield was measured (on seven fields in 1996). White and mottled varieties produced equal biomass (7.92 and 6.74 t ha−1 in 1996 and 1997 respectively), and more than the black variety (6.85 and 4.90 t ha−1 in 1996 and 1997 respectively). Mucuna increased 1996/97 second-season maize grain yields by 50 % (from 0.97 to 1.46 t ha−1). Plots previously cropped with white and mottled varieties produced greater maize yield (1.55 t ha−1) than did black-variety plots (1.29 t ha−1). The research confirmed the higher productivity of the white and mottled varieties and the potential of the rotational system. Allocating the more desirable first-season growth period to mucuna and the riskier second season to maize is problematic, but the system may have potential in the region as a short-term fallow that permits second-season maize production.

Genotype × environment interaction plays an important role in the identification of genotypes with high and stable yields. The environmental components of such interaction can be attributed to location (spatial) and year (temporal) factors. This study considers a specific aspect of the location factor, i.e. that locations not geographically close to each other are likely to vary in terms of the conditions that determine the effect of the year factor, even during the same calendar year. In these situations, the year effects are considered to be random variables within each location. This study addresses the question of whether genotype × location interactions are consistent (or repeatable) over time: a question which is crucial when defining the target environments in a plant breeding programme and when deciding the optimum environment for selection. Using three sets of data from field experiments, various computation methods were developed to estimate variance components; the methods and estimates are presented here. Using the bootstrapping procedure to sample one year from each location within a given calendar year, we obtained bootstrap replicated values of genotype × location interaction and their summary statistics, including the coefficient of variation (CV). We suggest that the CV can be used to measure the repeatability of genotype × location interactions. A Genstat program that can be used to perform the required computations is available from the authors upon request.

The feasibility of commencing tapping (‘opening’) of rubber trees for latex extraction at a lower stem girth (40 and 45 cm) than the currently recommended 50 cm was investigated in three different genotypes. The possibility of combining early opening with low frequency tapping and yield stimulation using Ethrel (LFT + E) was also examined. One of the genotypes tested, RRIC 121, gave a higher dry rubber yield, both per tapping and cumulatively over a given period, when opened at 40 cm than at 50 cm. Of the other two genotypes, one (RRISL 211) showed a clear reduction in yield with early opening, while the other (RRIC 102) did not show a significant yield response. Among the three genotypes tested, RRIC 121 showed the minimum depression in trunk girth increment. Analysis of yield components showed that the response of a given genotype to early opening and LFT + E is determined by the interaction between latex volume per tapping and dry rubber content (DRC), which were negatively correlated. RRIC 121 had a significantly greater DRC, which enabled it to maintain a higher dry rubber yield under early opening and LFT + E despite producing a lower latex volume than both the other genotypes. In contrast, despite producing a substantially greater latex volume than the other two genotypes, RRISL 211 did not produce a higher dry rubber yield because of its lower DRC. The higher DRC was also responsible for the greater response of RRIC 121 to yield stimulation with Ethrel, which reduced the plugging index and increased the initial latex flow rate. Early commencement of tapping in combination with LFT + E is therefore possible in rubber when amenable genotypes are selected, offering the potential of improving the economics of rubber production, especially for smallholders, in West Asia.

The results are presented of a trial with coconuts, testing progeny of 104 unselected seed parents. The progenies of the best 5 per cent of the parents, selected on their phenotypic values, gave yields 14 per cent above the progeny population mean, indicating that mass selection is effective. There was considerable variation in breeding values between the palms tested, and a higher frequency of desirable genotypes could be isolated when the parents were selected on yield of copra rather than when they were taken at random. Prepotency in coconut palms is discussed. Leaf production of the young palms within a family, during the first 40 months of their growth, was correlated with the breeding value of the parent.

Grain barley was grown either continually or in rotation with fallow in a 12-year experiment. Annual rainfall ranged from 120 to 297 mm. As the water requirement of the crop is 240 mm, growth in most seasons occurred under water stress. The amount of water conserved under fallow was only significant (75–100 mm) in three of the 12 years and only once did the water conserved increase barley yield in the following year. The total grain yield over the experimental period was twice as high in the barley–barley sequence as in the barley–fallow sequence.

Cultiuo continuo de cebada o después de barbecho

This paper describes the design of six data-recording forms which have been found to be acceptable by both field workers and data-processing staff. The reasons for the choice of design and hints on how to present the data are also given.

Effects of plant density were studied in field experiments carried out over four successive years as part of an evaluation of the potential of jackbean and in order to determine appropriate cultural practices for the crop. Flowering, biomass accumulation, and seed yield and its components were examined. Increased plant density led to earlier canopy development and biomass accumulation, and to increased seed yield in long growing seasons. Maximum seed yield ranged from about 1.0 to 3.8 t ha−1 between years of short and of prolonged rainy seasons, respectively. Plant size and branching were reduced at high density. Variation in seed yield was associated with differences in pod number; single seed weight and number of seeds per pod remained more constant

This paper presents the results of:

(a) On-farm trials (eight) over a two-year period designed to test the effectiveness of leguminous cover crops in terms of increasing maize yields in Igalaland, Nigeria.

(b) A survey designed to monitor the extent of, and reasons behind, adoption of the leguminous cover crop technology in subsequent years by farmers involved, to varying degrees, in the trial programme.

Particular emphasis was placed on comparing adoption of leguminous cover crops with that of new crop varieties released by a non-governmental organization in the same area since the mid 1980s. While the leguminous cover crop technology boosted maize grain yields by 127 to 136% above an untreated control yield of between 141 and 171 kg ha−1, the adoption rate (number of farmers adopting) was only 18%. By way of contrast, new crop varieties had a highly variable benefit in terms of yield advantage over local varieties, with the best average increase of around 20%. Adoption rates for new crop varieties, assessed as both the number of farmers growing the varieties and the number of plots planted to the varieties, were 40% on average. The paper discusses some key factors influencing adoption of the leguminous cover crop technology, including seed availability. Implications of these results for a local non-governmental organization, the Diocesan Development Services, concerned with promoting the leguminous cover crop technology are also discussed.

Resilient cropping systems are required to achieve food security in the presence of climate change, and so several long-term conservation agriculture (CA) trials have been established in southern Africa – one of them at the Chitedze Agriculture Research Station in Malawi in 2007. The present study focused on a longitudinal analysis of 10 years of data from the trial to better understand the joint effects of variations between the seasons and particular contrasts among treatments on yield of maize. Of further interest was the variability of treatment responses in time and space and the implications for design of future trials with adequate statistical power. The analysis shows treatment differences of the mean effect which vary according to cropping season. There was a strong treatment effect between rotational treatments and other treatments and a weak effect between intercropping and monocropping. There was no evidence for an overall advantage of systems where residues are retained (in combination with direct seeding or planting basins) over conventional management with respect to maize yield. A season effect was evident although the strong benefit of rotation in El Niño season was also reduced, highlighting the strong interaction between treatment and climatic conditions. The power analysis shows that treatment effects of practically significant magnitude may be unlikely to be detected with just four replicates, as at Chitedze, under either a simple randomised control trial or a factorial experiment. Given logistical and financial constraints, it is important to design trials with fewer treatments but more replicates to gain enough statistical power and to pay attention to the selection of treatments to given an informative outcome.

Uptake of the major nutrients by maize was determined throughout the growing season. Little phosphorus was accumulated, as reflected in its distribution within the plants, but uptake of labelled phosphorus showed two distinct peaks associated with root development. One fifth of the applied phosphorus was recovered by the plants.

Conocarpus lancifolius is an ornamental tree planted in Kuwait, resulting in more than 120 t of residual by-products daily. These residues could be utilised as ensiled feed. A total premix of 24 t of silage was prepared in six pilot-scale trench silos for 30 days, after which triplicate samples were taken from each trench silo, which were analysed for nutritional contents and microbial populations. Mean pH value was 4.2 ± 0.12, where mean of dry matter (DM), crude protein, crude fats, crude fibre, organic matter, lactic and acetic acids and total water soluble carbohydrate concentration were 35.10 ± 4.0%, 11.18 ± 0.07%, 2.47 ± 0.21%, 20.85 ± 0.95%, 19.53 ± 0.53%, 4.95 ± 0.32%, 1.47 ± 0.01% and 20.86 ± 0.56% on DM basis, respectively. Means of aerobic bacteria, fungi (yeast and moulds) and lactic acid bacteria counts were 1.8 ×104 ± 0.15, 1.1 × 104 ± 0.09 and 7.3 × 108 ± 0.12 colony forming units per gram of fresh silage, respectively. An animal performance trial was conducted on 60 Holstein Friesian heifers with initial live weights ranging from 262 to 275 kg, grouped in six dietary treatments for a 148-day feeding trial. The diets contained different ratios of Conocarpus silage, which ranged from 10 to 60% on DM basis partially replacing conventional roughage (alfalfa hay, straw). DM intake of heifers ranged between 11.40 ± 2.14 kg and 13.61 ± 2.54 kg. Daily live-weight gain ranged from 0.99 ± 0.38 kg to 1.20 ± 0.31 kg. From the results, Conocarpus silage could be suggested as a replacement for conventional roughage in rations for growing heifers.

The relations between sugar content and certain features of growth were followed in 16 sugarcane varieties during two crops. High sugar content was promoted by the absence of tillering during cane elongation, by a high leaf blade to joint weight ratio, by a long phyllochron, and perhaps slightly by a long life span of leaves. To combine high yield with high sugar content it is important to have a high tiller number early in growth, which appears to be promoted by delayed onset of cane elongation, small initial leaf size, and an upright leaf habit. To combine a small initial leaf size with a high leaf blade/joint weight ratio during elongation requires a large increase of leaf size during growth.

Colour development in fruits of dark purple eggplant cultivars was greatly influenced by temperature conditions. During the cool season, colour development was much slower than during the hot season, corresponding to slower fruit growth and much lower final weight. There were varietal differences in seasonal influence on the distribution of various colour shades, both during fruit growth and at harvest. Soil heating during the cool season improved fruit colour.

Climatic change affects global agriculture and is a severe threat to global food security due to variability of the three factors measuring climate change (CO2, temperature and precipitation) with temperature being the most crucial one. Wheat is severely affected by high temperatures with reproductive and grain-filling phases being most sensitive, impacting grain number, size and weight. Seed size and weight are the key agronomic traits subjected to artificial selection and involved in the domestication process since the origin of agriculture. Three genotypes Banks, EGA Gregory and Fang-60 with the latter known to be heat tolerant were grown under glass house conditions and subjected to heat stress for 3 days during early- (11–14 dpa – days post anthesis) and late- (27–30 dpa) grain filling stages in a mutually exclusive fashion. The impact of heat stress during early- and late- grain filling on the four major grain characteristics, thousand grain weight (TGW), grain length, grain width and grain thickness was assessed. The tolerant genotype Fang-60 exhibited significantly higher TGW during early-grain filling heat stress than the control possibly due to an ability to exploit the accelerated release of fertilizer under high temperature. Banks and EGA Gregory were moderately tolerant to susceptible to heat stress, respectively, at early- and late-grain filling with Fang-60 being tolerant to both early- and late- grain filling heat stress. This study confirms the availability of significant genetic variation in heat stress response in wheat that might be exploited to adapt wheat to higher growth temperatures.