The potential of cyanobacteria-based compost formulations was evaluated in cotton crop at two agro-ecological locations (Nagpur and Sirsa) as plant growth promoting (PGP) and biocontrol agents. Compost-based formulations fortified with Calothrix sp. or Anabaena sp. enhanced germination and fresh weight of plants, and microbiological activity by 10–15%, besides increased available nitrogen (by 20–50%) in soil at Nagpur. In the fungi-infected fields at Sirsa, Anabaena–T. viride biofilmed formulation performed the best, recording 11.1% lower plant mortality than commercial Trichoderma formulation. Scanning electron microscopy confirmed the colonisation of inoculated cyanobacteria/biofilms on roots. Significant correlation between mortality, increased activity of hydrolytic enzymes and fresh weight of plant roots were recorded. Calothrix sp. and Anabaena sp. proved promising as both PGP and biocontrol agents, while biofilmed formulations substantially reduced mortality of cotton plants in sick plots. This study illustrates the promise of cyanobacteria as viable inoculation option for integrated nutrient and pest management strategies of cotton.

Informal markets receive little attention from governments and researchers, despite their centrality to farmers' seed security. This paper documents the importance of informal markets for supplying seed and restocking critical plant genetic resources in normal and stress periods. It analyses farmers' rationales for using such markets and their strategic actions in selecting out seed from grain. Conceptual aids for differentiating among market goods – grain, ‘implicit seed’ and seed – are presented, including tracing of agro-ecological seed sources, traders’ seed management behaviour and seed/grain price patterns. Ethiopian case material gives rare insight into how different scales of traders manage the seed/grain divide. Better understanding of informal markets is an important precursor to strengthening them as such markets have unrealized potential to deliver more and higher quality seed, and a greater range of modern and local varieties. Support for informal seed markets could usefully feature in rural livelihood and social protection programmes, but this will require basic shifts in interventions and further refinements in market analysis.

A series of experiments was conducted on rice seedlings in a nursery seedbed and after transplanting in order to understand root and shoot characteristics, and their contribution to the production of tillers and dry matter. At the nursery stage, the seedlings' were studied at varying densities (high and low) and fertilizer treatments (with and without nitrogen) at 12 and 24 days after sowing (DAS) in wet or dry seedbeds. After transplanting, the effects of seedling age at the time of transplanting (12 and 30 days), method of raising seedlings (dry or wet seedbed) and water regimes (flooded or non-flooded) were studied. The overall aim was to understand the benefits, if any, of this system of rice intensification (SRI) management practices over conventional methods. The study revealed that in a nursery at 12 DAS, rice seedlings raised in a dry seedbed, irrespective of seeding density and fertilizer application, showed accelerated growth with better shoot and root characteristics in terms of greater leaf number, plant height, lateral root formation and elongation, and dry mass compared to seedlings grown in a wet seedbed. At 24 DAS, a significant interaction between seeding density and fertilizer application was found for dry-seedbed plants compared to those grown in a wet seedbed. Poor shoot and root growth was seen in older seedlings grown without fertilizer. Seedling age was found to be the most important factor affecting both shoot characteristics after transplanting (number of tillers, plant height, dry matter production) and root characteristics (root length density, root weight density). Younger seedlings performed better than older seedlings transplanted into either flooded or non-flooded soils with greater uptake of nitrogen and manganese than older seedlings. These results indicate that many of the constraints previously associated with non-flooded rice cultivation may be alleviated by transplanting younger seedlings that have been raised by SRI methods.

The properties are discussed of a number of relatively simple equations that describe non-linear relations of the type which frequently occur in biology. Most of the equations can be linearized by applying simple transformations (e.g. logy, log (a–y), I/y) to either y or x, or both. Some approximate methods of fitting the equations to experimental data are given, but statistical methods are not discussed in any detail.

Rapid climatic and socio-economic changes challenge current agricultural R&D capacity. The necessary quantum leap in knowledge generation should build on the innovation capacity of farmers themselves. A novel citizen science methodology, triadic comparisons of technologies or tricot, was implemented in pilot studies in India, East Africa, and Central America. The methodology involves distributing a pool of agricultural technologies in different combinations of three to individual farmers who observe these technologies under farm conditions and compare their performance. Since the combinations of three technologies overlap, statistical methods can piece together the overall performance ranking of the complete pool of technologies. The tricot approach affords wide scaling, as the distribution of trial packages and instruction sessions is relatively easy to execute, farmers do not need to be organized in collaborative groups, and feedback is easy to collect, even by phone. The tricot approach provides interpretable, meaningful results and was widely accepted by farmers. The methodology underwent improvement in data input formats. A number of methodological issues remain: integrating environmental analysis, capturing gender-specific differences, stimulating farmers' motivation, and supporting implementation with an integrated digital platform. Future studies should apply the tricot approach to a wider range of technologies, quantify its potential contribution to climate adaptation, and embed the approach in appropriate institutions and business models, empowering participants and democratizing science.

Simple methods are described for the analysis of daily rainfall measurements. The distinctive feature is that each year provides one number for any event or characteristic of interest. The resulting observations are then analysed, assuming that they are a simple random sample from a single distribution. An estimate of the probability of an event can be made directly from its relative frequency of occurrence, or alternatively a distribution (such as the normal) can be fitted. The methods are applied to agronomic questions on dry spells, the start, end and length of the growing season, and the distribution of amounts of rainfall through the year. Examples are given from Nigeria and India.

Crop residue management is posing a serious problem in the rice (Oryza sativa)–wheat (Triticum aestivum) cropping system, which is widely practised in the Indian Subcontinent and China, and covers about 22.5 × 106 ha. The problem is serious because there is very little turn-around time between rice harvest and wheat sowing. Three practices, namely, residue removal, residue burning and residue incorporation were compared in two field experiments, one with the rice residues and the other with the wheat residues. Results obtained showed that both rice and wheat residues can be safely incorporated without any detrimental effects on the crops of rice or wheat grown immediately after incorporation. Incorporation of crop residue also improved soil fertility status as judged by organic carbon and available phosphorus and potassium contents. Residue incorporation should be preferred over residue burning, which results in the loss of valuable plant nutrients and is both an environmental and a health hazard.

In Malawi, intensive production of maize (Zea mays) is pursued on over 60% of smallholder land, yet application of nutrients is almost nil. To improve adoption of soil productivity-enhancing technologies, two participatory methods were pursued: (i) a novel ‘mother-and-baby’ trial design and (ii) participatory action research with communities in a southern Malawi watershed. The central ‘mother trial’ was managed by researchers (replicated within a site) and systematically linked to farmer-managed ‘baby’ trials to cross-check biological performance with farmer assessment. The watershed approach involved a partnership of researchers and farmers addressing soil management. Technologies tested in both approaches integrated legumes into existing maize-based systems, sometimes in combination with inorganic fertilizers. Across methods, legume intensification increased yields by approximately 40% (net benefit increase of approximately US$50 ha−1) and fertilizer increased yields by approximately 70% compared with continuous maize grain yields of about 1100 kg ha−1. Farmer assessment prioritized technologies that included secondary benefits, such as weed suppression, grain legume yields, and low-labour-demanding fertilizer. A survey indicated that participating researchers and extension staff had reservations about the amount of time required to interact with farmers, and no clear consensus emerged regarding the best approach. There has been wider adoption of the mother-and-baby trial method by scientists in neighbouring countries, indicating the value of systematically incorporating farmers' input.

Nitrogen efficiency from Azolla microphylla or Sesbania rostrata green manure, rice straw, and inorganic fertilizer-N was compared in two long-term experiments with irrigated lowland rice (Oryza sativa L.). Treatments included a control and each nitrogen source alone or in combinations that provided 50% of the total applied nitrogen from an organic and inorganic nitrogen source. All nitrogen sources were applied at equivalent nitrogen rates to 19–22 consecutive rice crops. Residual effects were assessed in two subsequent cropping seasons at one site. Lower grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptake were obtained from green manure and rice straw nitrogen as sole or dual nitrogen sources rather than from a standard split application of prilled urea. Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen, and greater extractable soil nitrogen in the vegetative growth period. After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source. Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than use of green manure because rice straw is often a wasted resource in irrigated rice systems of the humid tropics, the efficiency of rice straw nitrogen in combination with prilled urea is comparable to green manure nitrogen, and the increase in soil nitrogen from rice straw was 50–150% greater than from green manure.

This study was conducted to investigate the physiological response of sugarcane genotypes to drought and its consequence for stalk yield. Sugarcane genotypes IACSP94-2094, IACSP96-2042 and SP87-365 were subjected to water deficit during the initial growth phase by withholding water. Resistance and sensitivity patterns were defined by the impact of drought on the stalk yield and content of soluble solids in the stalk juice. IACSP94-2094 and SP87-365 were considered drought-resistant genotypes, as the stalk dry matter production and yield of soluble solids were not reduced by the water deficit. Although drought caused reductions in leaf gas exchange in all the genotypes, IACSP96-2042 was most affected when considering the cumulative reduction in photosynthesis throughout the experimental period. This photosynthetic impairment of IACSP96-2042 was related to both non-stomatal and stomatal limitations, whereas photosynthesis in SP87-365 and IACSP94-2094 were only stomatally limited under drought. In general, a reduced photosynthetic sensitivity to water deficit was an important physiological trait for dry matter production in sugarcane plants, and the concentrations of soluble carbohydrates, sucrose, starch and proline in the leaves did not reveal consistent differences between the patterns of resistance and sensitivity. Even though IACSP96-2042 was severely affected by water shortage, this genotype presented a similar stalk yield under drought and the highest stalk yield under well-watered conditions when compared to the other genotypes. This response to variable water conditions is interesting for regions with seasonal drought, whereas the pattern of drought resistance is more appropriate for regions in which drought occurs for long periods during the crop season. Our findings are also discussed from the point of view that increases in sugarcane yield and sustainable agriculture may be reached by choosing the best genotype for each specific environmental condition.

Inoculating Zea mays (three cultivars), Sorghum bicolor, Panicum miliaceum and Setaria italica with nitrogen-fixing bacteria of the genus Azospirillum in Northern Negev and Bet Shean Valley field experiments resulted in significant increases in yield of grain and foliage of commercial value. It was concluded that inoculating summer cereal crops in Israel may save valuable nitrogen fertilizer.

Research and observations on how climate effects the growth and yield of the tea plant are reviewed. Despite differences in the types of tea grown and the cultural techniques practiced in the different tea areas, an attempt is made to define quantitatively the climatic conditions needed to maintain growth rates at a high level. The need for critical work in the future is emphasized.

Enset (Ensete ventricosum) production is declining, and it faces genetic erosion due to drought, diseases and population pressure. Participatory Rural Appraisal (PRA) and additional formal survey studies on 315 households were conducted over three consecutive years (1998–2000) in the Sidama, Wolaita and Hadiya ethnic regions of southern Ethiopia to assess traditional cultivation methods, analyse the production systems, and evaluate farm-based enset biodiversity. The regions differ in terms of cultural background, resources, farming systems, population density, and agro-ecology. Furthermore, the methods for initiating suckers and the frequency of transplanting vary among the three regions.

Diverse enset landraces were identified in the Sidama (52), Wolaita (55) and Hadiya (59) regions. Sidama farmers had the highest number of landraces per farm, 57% and 21% more than found on Wolaita and Hadiya farms respectively. In all three regions, landrace diversity was influenced by household resources, cultural background, population pressure, and agro-ecology. There were significant differences in the average number of enset landraces and livestock between rich and poor households in the three regions. Rich farmers had more land and manure-producing livestock, and they planted more enset landraces than did poor farmers. In all three regions, women proved to be more experienced than men in identifying enset landraces.

The number of enset landraces per farm was significantly correlated with other household characteristics for resource-rich Sidama farmers and with the number of livestock and area of farmland for resource-rich Hadiya farmers. This suggests that middle-income or poor farmers concentrate on annual crops, rather than on growing the perennial enset plant. More research is needed to identify, characterize and conserve genetic diversity, and to improve the cultivation practices for enset. The cultural, socio-economic, and gender-associated aspects of enset cultivation need to be assessed to understand the dynamics of enset biodiversity.

Continuous cultivation of rice–wheat cropping system in the Indo-Gangetic plains is under threat with decline in soil organic carbon (SOC), total factor productivity and overall sustainability. Pulses, an important component of crop diversification, are known to improve soil quality through their unique ability of biological N2 fixation, leaf litter fall and deep root system. Therefore, the effect of inclusion of pulses in the puddled rice system under organic and inorganic amendments on SOC pool and its management indices were evaluated in a long-term experiment after seven cropping cycles. The results indicated that inclusion of pulses in the rice-based system improved the SOC content, being greater in surface soil (0–20 cm) and declining with soil depth. Among the four carbon fractions determined, less labile carbon fraction (Cfrac3) was the dominant fraction in the puddled rice system, particularly under organic treatments, indicating that it is possible to maintain organic carbon for longer time in this system. The rice–wheat–mung bean system resulted in 6% increase in SOC and 85% increase in soil microbial biomass carbon as compared with the conventional rice–wheat system. Application of crop residues, farm yard manure (5 t ha−1) and biofertilisers had greater amount of carbon fractions and carbon management index (CMI) over control and the recommended inorganic (NPKSZnB) treatment in the soil surface, particularly in the system where pulses are included. Interestingly, in the puddled rice system, passive carbon pool is more in surface soil than deeper layers. The relative proportion of active carbon pool in surface layer (0–20 cm) to subsurface layer (20–40 cm) was highest in rice–wheat–rice–chickpea (1.14:1) followed by rice–wheat–mung bean (1.07:1) and lowest in the rice–wheat system (0.69:1). Replacing wheat with chickpea either completely or during alternate year in the conventional rice–wheat system also had positive impact on SOC restoration and CMI. Therefore, inclusion of pulses in the rice-based cropping system and organic nutrient management practices had significant impact on maintaining SOC in an Inceptisol of the Indo-Gangetic plains of India.

Microclimate and soil fertility were measured under and away from the canopies of small and large scattered trees of néré (Parkia biglobosa) and karité (Vitellaria paradoxa) to explain their influence on pearl millet (Pennisetum glaucum). During the rainy season, photosynthetically active radiation under both tree canopies was reduced to 24% of incident radiation but, surprisingly, millet biomass was not significantly different from that in the open. Millet seedlings under the tree canopies experienced only 1–9 h week−1 of supra-optimal temperatures (>40 °C) compared with 27 h week−1 in the open. Reduction in windspeed and soil evaporation was observed under the trees but was unlikely to have a significant influence on millet growth since water was not limiting (rainfall = 920 mm).

Exchangeable potassium, percentage carbon and pH were significantly higher and δ13C lower in soil under trees than in the open. Nitrogen levels were not significantly higher than in the open except for large néré trees. Carbon derived from C3 plants, calculated from δ13C, was significantly higher in soils under trees than in the open and is recommended as a good indicator of the influence of trees on soils. These results show that the combined beneficial effects of temperature modifications and soil fertility could exceed the negative effect of tree shade.

New initiatives in agroforestry are seeking to integrate indigenous trees, whose products have traditionally been gathered from natural forests, into tropical farming systems such as cacao farms. This is being done to provide from farms, marketable timber and non-timber forest products that will enhance rural livelihoods by generating cash for resource-poor rural and peri-urban households. There are many potential candidate species for domestication that have commercial potential in local, regional or even international markets. Little or no formal research has been carried out on many of these hitherto wild species to assess potential for genetic improvement, reproductive biology or suitability for cultivation. With the participation of subsistence farmers a number of projects to bring candidate species into cultivation are in progress, however. This paper describes some tree domestication activities being carried out in southern Cameroon, especially with Irvingia gabonensis (bush mango; dika nut) and Dacryodes edulis (African plum; safoutier). As part of this, fruits and kernels from 300 D. edulis and 150 I. gabonensis trees in six villages of Cameroon and Nigeria have been quantitatively characterized for 11 traits to determine combinations defining multi-trait ideotypes for a genetic selection programme. I. gabonensis fruits are rich in vitamin A (67 mg 100 ml−1), while the kernels are rich in fat (51.3%) and contain a polysaccharide that is a food thickener. The fruits of D. edulis are also rich in oil (31.9%) and protein (25.9%). This poverty-reducing agroforestry strategy is at the same time linked to one in which perennial, biologically diverse and complex mature-stage agroecosystems are developed as sustainable alternatives to slash-and-burn agriculture. To meet the objective of poverty reduction, however, it is crucial that market expansion and creation are possible. Hence, for example, it is important to determine which marketable traits are amenable to genetic improvement. While some traits (such as fruit and kernel mass) that benefit the farmer are relatively easy to identify, there are undoubtedly others that are important to the food, pharmaceutical or other industries which require more sophisticated chemical evaluation. There is a need, therefore, for better linkages between agroforesters and the private sector. The domestication activities described are relevant to the enrichment of smallholder cacao farms and agroforests. This diversification is seen as being important for the support of the cacao industry.

Seven sorghum lines, flowering from 50 to 87 days after sowing, were subjected to early drought stress, late stress, and both early and late stress in the field during the dry season in India. Panicle initiation was delayed by 2–25 days and flowering by 1–59 days by the drought stress treatments, the greatest effect being in the treatment subjected to both early and late stress. Stress increased the period between panicle initiation and flowering by retarding the rate of panicle development; when stress was severe panicle development stopped. Upon relief of stress following irrigation, panicle development resumed at rates comparable to those in a fully irrigated control. The rate of leaf appearance was affected in a similar manner to panicle development soon after water was withheld. Rate of leaf appearance and panicle development decreased as pre-dawn leaf water potential decreased and ceased at water potentials of −0.55 and −0.7 MPa, respectively.

Plants of two genotypes of chickpea (Cicer arietinum), classified as early or late-maturing in the field, and relying either on dinitrogen fixation by nodules or on nitrate-N, were grown in various simulated tropical environments in growth cabinets. Plants were transferred between cabinets at various times so that they experienced either warm (30°C) or hot (35°C) days (both in combination with a typical night temperature of 10°C) for different durations of reproductive growth, after growing in average (30°C day - 10°C night) or warmer than average (30° - 18°C) temperatures for the first 28 days from sowing and then average temperatures until transferred into the hot regime. Diurnal vapour pressure deficits were adjusted so that plants experienced a constant atmospheric relative himidity (70%) in all thermal regimes. The greater the proportion of the reproductive period spent in hot days the smaller the seed yields produced; plants transferred at 50% flowering were almost barren. The implications of these data for breeding chickpeas well adapted to hot environments are discussed.

Increased labour costs and area under irrigation, the development of modern early-maturing varieties and improved fertilizer and weed management techniques have encouraged many farmers in the Philippines, Malaysia and Thailand to switch from transplanted to direct-seeded flooded rice culture. This paper summarizes the development and spread of the technology for direct-seeded flooded rice in southeast Asia and the contribution made by research at IRRI and by national programmes. It covers research on crop establishment, varietal requirements, fertilizer management, weed control and economics and examines the advantages and disadvantages of direct-seeding compared with transplanting.

The mean time for 50% germination at 20 °C of 12 Indian wheat (Triticum aestivum) cultivars was nearly halved, from 51 h to 27 h, by soaking seed in water for 8 h prior to sowing. A delay of 24 h without further soaking, intended to simulate postponement of sowing, reduced the time saved by priming to 16%. Priming had no effect on final germination percentage. These results were used in the design of 275 on-farm, farmer-managed, participatory trials of seed priming in wheat during the 1997–98 and 1998–99 rabi (post-monsoon) seasons. In forty-one trials in tribal areas of Bihar and West Bengal states of India, seed priming gave a 13% grain yield advantage for farmers growing wheat in marginal areas with low levels of agricultural inputs. Mean benefits from seed priming of wheat in nine trials in Chitwan, Nepal were 17%. In high potential areas of Gujarat, India, 205 trials had higher rates of input use. Yield benefit from priming in these trials averaged only 5% but constituted an extra 200 kg ha−1 grain at little or no cost. In 20 trials on marginal land, with slightly saline irrigation water in Ahmadwala, Pakistan, an average yield increase of 36% was obtained using seed primed with a 0.2% gypsum solution. Collaborating farmers reported that priming wheat seed overnight resulted in faster, more complete emergence, more vigorous early growth, better tillering, earlier flowering, larger ears, earlier maturity and higher yields. In addition, many farmers also reported that foliage in primed plots was a darker shade of green than that in non-primed plots, suggesting that primed plants may have been using nitrogen more efficiently. Seed priming was popular with farmers, most of whom reported that they would prime wheat seed the following year. A survey in Gujarat in 1998–99 of 63 farmers who had tested priming in 1997–98 showed that, while 65% had primed some of their own seed, none had primed more than 50 kg, suggesting that there were practical difficulties in priming larger volumes of seed.