Using experience with bambara groundnut (Vigna subterranea), this paper examines how local knowledge, genetic evaluation, research in fields, glasshouses and laboratories, and crop simulation modelling might be linked within a methodological framework to assess rapidly the potential of any underutilized crop. The approach described is retrospective in that each activity was not clearly defined and structured at the outset. However, the experience gained may help to establish a methodology by which growers, researchers and international agencies can integrate their knowledge and understanding of any particular underutilized crop and apply similar principles to accelerate the acquisition of knowledge on other underutilized species. The use of a methodological framework provides a basis for activities that maximize knowledge, minimize duplication of effort, identify priority areas for further research and dissemination, and derive general principles for application across underutilized crops in general. It also allows policy makers and planners to make comparative decisions on the nutritional, economic and research importance of different underutilized and more-favoured species. In particular, the incorporation of a generic crop simulation model within the methodological framework may assist growers, extension agencies and scientists to refine general recommendations for any particular crop to local conditions. Also, the incorporation of information gathered from the field, laboratory or market can be used to update rapidly the predictive capacity of the model for each crop.

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Measurements of respiration were made on leaf discs from glasshousegrown soybean (Glycine max [L.] Merr. cv 'Corsoy') plants in the presence and absence of cyanide (KCN) and salicylhydroxamic acid (SHAM). 02 uptake by mature leaves measured at 25°C was stimulated by 1 millimolar KCN (63%) and also by 5 millimolar azide (79%).SHAM, an inhibitor of the alternative oxidase and a selection of other enzymes, also stimulated 02 uptake by itself at concentration of 10 millimolar. However, in combination, KCN and SHAM were inhibitory. The rate of 02 uptake declined consistently with leaf age. The stimulation of 02 uptake by KCN and by SHAM occurred only after a certain stage of leaf development had been reached and was more pronounced in fully expanded leaves. In young leaves, 02 uptake was inhibited by both KCN and SHAM individually. The uncoupler, p-trifluoromethoxy carbonylcyanide phenylhydrazone, stimulated leaf respiration at all ages studied, the stimulation being more pronounced in fully expanded leaves. The uncoupled rate was inhibited by KCN and SHAM individually. The capacity of the cytochrome path declined with leaf age, paralleling the decline in total respiration. However, the capacity of the alternative path peaked at about full leaf expansion, exceeding the cytochrome capacity and remaining relatively constant. These results are consistent with the presence in soybean leaves of an alternative path capacity that seems to increase with age, and they suggest that the stimulation of 02 uptake by KCN and NaN3 in mature leaves was mainly by the SHAM-sensitive alternative path. The stimulation of 02 uptake by SHAM was not expected, and the reason for it is not clear.

Bambara groundnut (Vigna subterranea) is a grain legume crop, which is increasingly popular as food in rural areas across the African continent. However, reliable information pertaining to management of the crop is limited. Field experiments were conducted in Swaziland in the 1998/99 and 1999/2000 cropping seasons to determine the influence of sowing date and environmental factors on the growth, development and yield of bambara groundnut. In the 1998/99 season, seeds of one local landrace were sown on six dates between mid-September 1998 and mid-February 1999. In 1999/2000, seeds of two local landraces were sown on six dates between mid-October 1999 and late January 2000. The highest pod yield and total dry matter production were achieved in November sowings, with maximum pod yields of 1.3 and 0.64 t ha −1 for the 1998/99 and 1999/2000 seasons, respectively. Earlier sowing and successive delays in sowing from November caused substantial yield declines of as much as 72-75%. Sowing date influenced yields of bambara groundnut through the effect of temperature and daylength on plant development. For the landraces used in the study, while the rate of progress from sowing to flowering was influenced by temperature, the rate of progress from flowering to podding was influenced largely by daylength. The practical implications of the results for increased bambara groundnut production are discussed.