Horsegram (Macrotyloma uniflorum) is sown late in the rainy season by resource-poor farmers in marginal, drought-prone areas of India. Sowing and early crop growth coincide with declining rainfall so crop establishment is often poor and yields are low. Horsegram is a ‘neglected’ crop and farmers' choice of varieties to grow is limited to poor-yielding landraces or to modern varieties for which access to seed is limited. In on-station trials, we compared the yield and relative merits over three years of seven varieties potentially suited to conditions in Jharkhand State and sown with or without priming by soaking seeds in water prior to sowing. Yield stability of the varieties was tested using data from these and five additional trials. Farmers' opinions were recorded during six participatory exercises based on farmers' trials, and their rankings were compared with those from the on-station evaluations. Significant variety × year interactions were observed and yield was generally inversely proportional to drought. Both linear and non-linear genotype × environment interactions were significant for all varieties. Variety BK 1 was the most desirable with stable yields across environments and a higher overall mean grain yield. Variety VLG 1 was unresponsive to more favourable environments but yielded more in the low yielding environments. However, it was the earliest to mature and was identified as a promising variety, which farmers preferred for its grain and brown seeds. This could be used to diversify farming systems with additional options for farmers. Although soaking seeds for 12 h was most effective in increasing germination in an in vitro study, soaking for 8 h before sowing increased emergence and final stand by 11 % and grain yield by 10 % averaged over all varieties and years. Soaking advanced flowering by 1.3 d and maturity by 1.9 d. All varieties responded positively to soaking and did so in all three years, although the response was stronger in drier years.

Daily measurements of moisture by neutron probe showed an erratic pattern of ET in the Sudan Gezira, attributed to the redistribution of water and development of cracks in a drying profile. However, dividing an irrigation cycle into periods of 3–5 days revealed a unique trend of ET that was consistently low in the early period, increased to a maximum in the middle, and fell off at the end. Roots suffer from anaerobic conditions for about 5 days after flooding but subsequent drying and cracking improves soil aeration that leads to final depletion of profile moisture and depression of ET.

Growth and water use of sole crops and intercrops of morphologically contrasting maize and pea cultivars were measured in two years. The maize cultivars were Nancis with erectophile and Sophy with planophile leaves and the pea cultivars Maro a leafy pea and Princess a semi-leafless pea. In the first part of the season water use was lower for sole maize but intercrops and sole pea used similar amounts of water. By 90 days after sowing, when peas had matured, all crops had used similar amounts of water. Maize had slightly greater water use efficiency than peas. Cultivars Nancis and Princess tended to have greater water use efficiency than Sophy and Maro respectively. Intercrops produced more dry matter than sole crops and therefore had consistently greater water use efficiencies.

A micrometeorological experiment was carried out in an area of soyabean cultivation located in northeastern Para state, Brazil, in order to evaluate impacts on the local energy balance due to replacement of forests by soyabean. The meteorological data from forest ecosystems were collected in Caxiuanã forests located in central Para. The energy balance components were obtained using the Bowen ratio technique. Differences in energy balance components between ecosystems were significant during the soyabean growing season and more significant between growing seasons. During the soyabean growing season mean impacts of −15%, −9% and −27% on net radiation, latent heat flux (LE) and sensible heat flux (H), respectively, were observed. At specific soyabean stages, LE was higher than in the forest because of the high soyabean surface conductance of water vapour. However, during the production off-season the impacts were more significant (p < 0.05), showing a reduction of 78% in LE and a substantial increase in H (84%) because of the absence of vegetation cover over this period.

Competition from weeds is one of the major biophysical constraints to rice (Oryza spp.) production in sub-Saharan Africa. Smallholder rice farmers require efficient, affordable and labour-saving weed management technologies. Mechanical weeders have shown to fit this profile. Several mechanical weeder types exist but little is known about locally specific differences in performance and farmer preference between these types. Three to six different weeder types were evaluated at 10 different sites across seven countries – i.e., Benin, Burkina Faso, Côte d'Ivoire, Ghana, Nigeria, Rwanda and Togo. A total of 310 farmers (173 male, 137 female) tested the weeders, scored them for their preference, and compared them with their own weed management practices. In a follow-up study, 186 farmers from Benin and Nigeria received the ring hoe, which was the most preferred in these two countries, to use it during the entire crop growing season. Farmers were surveyed on their experiences. The probability of the ring hoe having the highest score among the tested weeders was 71%. The probability of farmers’ preference of the ring hoe over their usual practices – i.e., herbicide, traditional hoe and hand weeding – was 52, 95 and 91%, respectively. The preference of this weeder was not related to gender, years of experience with rice cultivation, rice field size, weed infestation level, water status or soil texture. In the follow-up study, 80% of farmers who used the ring hoe indicated that weeding time was reduced by at least 31%. Of the farmers testing the ring hoe in the follow-up study, 35% used it also for other crops such as vegetables, maize, sorghum, cassava and millet. These results suggest that the ring hoe offers a gender-neutral solution for reducing labour for weeding in rice as well as other crops and that it is compatible with a wide range of environments. The implications of our findings and challenges for out-scaling of mechanical weeders are discussed.

Improved upland rice cultivars introduced in Volta Region, Ghana, have been perceived to store poorly compared to farmers' traditional cultivars. A survey was conducted in 2003 in the Hohoe district of this region, where a Participatory Varietal Selection programme had started in 1997, to gain insight into farmers' seed production and storage practices that are likely to affect seed quality in storage. Farmers rated keeping quality (p < 0.001), tolerance to storage pests (p < 0.001), seed quality (p < 0.001) and establishment of their local cultivars Kawomo, Viono and Wuwulili as much better than the improved cultivar IDSA 85. Initial seed moisture content ranged from 12.8 to 18% and germination from 0 to 82%. There was a significant relationship between seed moisture content and duration of drying prior to storage (p < 0.001) and storage method (p = 0.015). Germination loss in storage was rapid at high moisture content and slow at low moisture content. Between 60 and 80% of seeds germinated after six months storage at 12.8% moisture content. The viability equation predicted accurately germination of farmer-saved seed stored under ambient temperature in Ghana. Except for the japonica rice cultivar WAB 126-18-HB, the traditional cultivars Kawomo, Viono and Wuwulili survived better in storage than improved cultivars. There is a need to improve seed quality of improved cultivars if farmers are to benefit from their higher yields and grain quality and to improve storage practices.

Trees are important sources of food in both the humid and semi-arid tropics. Some species have been exploited for centuries and are widely distributed around the world, others have been cultivated only in limited areas, while most are still essentially wild. The potential for rapid genetic improvement by clonal selection is enormous and well-proven by the recent history of some species. Trees can yield as much food per hectare as most C3 annual crops – although special problems may have to be overcome to ensure regular bearing of fruit and nut trees. Trees also offer great ecological and social benefits.

A review is presented of available documents containing statistical methodology for participatory on-farm research. Further needs in this area of work are commented upon.

Seed yam production potential of three yam species (Dioscorea rotundata, Dioscorea alata and Dioscorea cayenensis) was assessed for two systems – the traditional method using 100 to 200 g setts, and the mini-sett technique using 25, 20, 15 and 10 g setts cut from mother tubers. The mini-sett technique required only 6–33% of the number of tubers needed for the traditional planting system, and resulted in plants superior to those produced by the traditional method in all their production attributes especially in the case of D. alata and D. rotundata.

The effect of drought and temperature on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled environment glasshouses in the United Kingdom. There were two landraces, S19-3 (from a hot, dry environment; Namibia) and Uniswa Red (from a cool, wet environment; Swaziland), two temperature regimes (23 °C and 33 °C) and three watering regimes (2006; fully irrigated), 2007 (drought imposed at 77 days after sowing (DAS)) and 2008 (drought imposed at 30 DAS)). Bambara groundnut responded to drought by slowing the rate of leaf area expansion and reducing final canopy size and total dry matter (TDM). Drought also caused significant reductions in pod dry matter, pod numbers and harvest index (HI), leading to a decrease in final yield that was different between landraces. Throughout the three growing seasons, landraces grown at 33 °C produced more TDM than the landraces grown at 23 °C. The two landraces differed in their phenology; S19-3 exhibited a reduced phenology where leaf numbers started to decrease before Uniswa Red at both temperatures, while Uniswa Red maintained the longest life cycle. The lowest pod yield was produced by Uniswa Red in 2008 at 33 °C (maximum of 35.5 gm−2), while S19-3 produced a minimum pod yield of 56.6 gm−2 at 33 °C, also in 2008. However, both landraces produced considerably more pod yield at 23 °C throughout the three growing seasons (minimum of 151 gm−2 and 162 gm−2 for Uniswa Red and S19-3, respectively). Under moderate drought, S19-3 at 33 °C gave the highest pod yield (365 gm−2) among the treatments throughout the three growing seasons and maintained HI better under drought. Despite being from a hot, dry environment, S19-3 also performed well at low temperature, which indicates the adaptation of S19-3 to low temperature that it also experiences in the country of origin.

The numbers of bacteria and the nitrogen fixing efficiency of isolates of Rhizobium leguminosarum, R. ciceri and R. meliloti with appropriate legume crop species were determined from soils collected from a wide range of locations in Turkey with elevations between 500 and 2200 m. For vetch and lentil nodulated by R. leguminosarum, many native rhizobia are present in most locations but they often have limited nitrogen fixation capacity. However, for chickpea nodulated by R. ciceri, relatively small numbers of bacteria and the almost universal ineffectiveness of fixation capacity point to a need for artificial seed inoculation of chickpea crops as a future agronomic priority. The wide range of bacterial numbers, considerable geographic inconsistency and generally low effectiveness of the indigenous rhizobia associated with the annual Medicago spp. suggest that inoculation would initially be a sensible precaution for all sowings.

Biodiversidad del rhizobium en Asia occidental

Lagière's B9 from Allen 51–296 (Gossypium hirsutum) was found to be non-homologous with Knight's B genes B1–B7, B9 and Bherb. To differentiate between this gene and Knight's B9 from G. herbaceum the symbols have been changed to B9L and B9K respectively. It was impossible to test Knight's B10 from Kufra Oasis G. punctatum and Lagière's B10 from Allen 51–296, but to avoid confusion it is proposed that these genes should be known as B10K and B10L.

Continuous cropping of a tropical Ultisol with or without nitrogen fertilizer increased soil acidification and reduced soil organic matter and productivity. Addition of nitrogen fertilizer failed to increase yields. This was apparently due to the decline in soil pH, an increase in the amount of soluble aluminium, and consequent inefficient utilization of added nutrients. Continuous use of ammonium sulphate as a nitrogen source hastened the development of both surface and subsoil exchange acidity.

A four-year study from 1958 to 1962 showed that time of application of fertilizer nitrogen greatly influenced the yield of grain, the percentage of nitrogen and the crude protein of the grain under Nigerian conditions characteristic of the early maize cropping season from March to July. Split applications of nitrogen fertilizer significantly increased maize grain yield by 35 per cent when two equal doses were given one month and two months after planting; and by 31 per cent when four equal doses were supplied at planting and one month, two months and three months after seeding. Yield was significantly reduced when application was delayed two months after planting. High yields of maize were not obtained by supplying the whole of nitrogen fertilizer at one time, eidier at sowing or any time later during the growing season. However, applying all of the nitrogen fertilizer one month after planting significantly increased the percentage of nitrogen and of the crude protein content of the grain. The maize ear weight was favourably influenced by spreading the nitrogen application over the three-month period of the maize growth.

Much recent research has been directed at intercropping. Although the planning and analysis of these experiments often raises complicated statistical questions, many statisticians have concentrated on sophisticated graphical and numerical procedures for summarizing results, without considering what system of intercropping, if any, is on balance advantageous to the farmer and how its advantage is to be measured. This paper surveys aspects of intercropping that need examination before farmers can be advised, such as the value of produce, and the effects of intercropping on yields and costs. Any synergism of productivity occurring directly or in the longer term is a central but not necessarily decisive aspect of the problem. A recently described experiment is used as an example. The main conclusion is that experiments on these topics need to be large and well-designed, with repetition in several years, and that interpretation must allow for alternative sets of numerical values expressing values and costs.

Application of biochar to rice has shown to elicit positive environmental and agricultural impacts due to its physicochemical properties. However, the relationship between greenhouse gas (GHG) emissions, rice yield, and soil nutrient status under biochar amendment remains unclear. In this study, rice yield and methane (CH4) and nitrous oxide (N2O) emissions were quantified in response to biochar application rate (0, 10, 20, and 40 t ha−1) to early and late subtropical rice cropping systems. We found that application of 10 t of biochar ha−1 to early rice reduced average CH4 emission fluxes, while all biochar application rates diminished average emissions in late rice paddy. Total global warming potential (GWP) and GHG intensity (GHGI) were inherently greater in late rice than early rice cropping. In early rice, GWP and GHGI were found to be similar between soil control, 10 and 20 t of biochar ha−1 treatments, although the largest occurred in the 40 t of biochar ha−1 treatment, whereas in late rice cropping, they were not affected by biochar application rates. Compared to the nil-biochar application, biochar application at varied rates did not affect rice yield. However, compared to 10 t biochar ha−1, increasing biochar application rate to 40 t ha−1 significantly decreased total rice yield (sum of early and late cropping). Generally, application of biochar increased soil salinity and total Fe and Fe2+ content while reducing soil bulk density. Temporal effects of biochar application were noted on CH4 emission flux, soil temperature, and soil Fe2+ and Fe3+ in early rice; and soil temperature, salinity, NH4+-N, NO3−-N, and soil Fe2+ and Fe3+ in late rice. This study confirms that the application of biochar at the lower rate of 10 t ha−1 is optimal for maintaining rice yield while reducing GHG emissions. Moreover, the study demonstrates the potential benefit of biochar in sustainable subtropical rice production.

The experiment examined how nitrogen applied to a maize crop was partitioned when the maize was intercropped with beans. Treatments consisted of 2, 4 and 6 rows of beans at within-row spacings of 20 or 10 cm sown between ‘maize' rows in which maize was either present or absent. Nitrogen was applied at 0, 30, 60, 90 or 120 kg ha−1. Maize showed a large response to nitrogen and this was little affected by beans. All bean rows in all positions showed some response to nitrogen. The largest response was from the rows closest to the maize, but this response was similar whether these rows were 20, 40 or 60 cm from the maize. Beans gave a much greater response in the absence of maize, indicating that the main factor determining the partitioning of the nitrogen between the two crops was the superior competitive ability of the maize. It is suggested that the approach could be suitable for examining nitrogen partitioning in other non-legume/legume situations.

Forage production of common vetch in semi-arid Mediterranean regions can be increased by varietal improvement. Dry matter content and crude protein yield were affected by environment more than crude protein content and harvesting date. Forage produced in environments where plants grew quicker was of lower dry matter content, higher crude protein content but of similar weight as forage produced in late environments. Variations in annual rainfall explained 35 to 76% of the total variation in dry matter yield.

The effects of rootstock on tree development, leaf nutrient levels and yields of two old-clone lemon cultivars, Eureka and Villafranca, were studied. The largest canopy development and yields were obtained on Alemow and Volkameriana; red rough lemon failed due to foot rot; Rangpur lime trees were severely stunted; and Citremon induced high chloride and relatively low boron contents in the leaves.

Growth and developmental stages of Alaska peas, from planting to dry seed maturity, were examined and described. Node counts were determined by designating the cotyledonary node as 0 and counting successive nodes up the plant to the highest visible one with unexpanded stipules. Five additional nodes are already determined in the shoot apex beyond the highest one with unexpanded stipules, indicating that damage to the shoot apex would result in losses of flowers and fruits that would have developed later if damage had not occurred.