Crop yield response to water - Cra

Lead AuthorAsha Karunaratne(formerly University ofNottingham, School ofBiosciences, UK; currentlyUniversity of Sabaragamuwa,Belihuloya, Sri Lanka)Bambara GroundnutContributing AuthorSayed Azam-Ali(University of Nottingham andCFFRC, Malaysia Campus,Jalang Broga, SelangorDarul Ehsan, Malaysia)AcknowledgmentsGabriella Izzi(formerly FAO, Land andWater Division, Rome, Italy;currently WB,Washington, USA),Pasquale Steduto(FAO, Land and WaterDivision, Rome, Italy),European Union INCO STD-3,FP5 and FP6 ProgrammesScientistscontributing withexperimental dataand tests for thecalibration ofAquaCroPIbraheem Al-Shareef,Stanley Noah,Rutger Cornelissen(University of Nottingham,School of Biosciences,Nottingham, UK),Abu Sesay(Botswana College ofAgriculture, Gaborone,Botswana)General descriptionBambara groundnut (Vigna subterranea) is an indigenous foodlegume crop that originated in the regions between the Jos Plateauin northern Nigeria and Garu in Cameroon. The variety subterraneais the cultivated form with wild forms belonging to variety spontanea(Pasquet et al., 1999). No established varieties exist and, to date, there havebeen no coordinated programmes of crop improvement, resulting in highgenetic variability within cropped fields. Marginal and subsistence farmersin Africa grow locally selected ‘landraces’, which are often grown fromseeds stored from previous harvests or from unregulated supplies of seedsbought from local markets.Bambara groundnut has been grown widely in Africa for many centuriesand now plays a significant role in cropping systems in semi-arid sub-Saharan Africa. It is mainly grown by women farmers for the subsistence oftheir families, often intercropped with cereals, tuber crops, vegetables, andother legumes (Linnemann, 1991). Bambara groundnut has been introducedthrough historical migrations to Indonesia, Thailand and Malaysia. Morerecently, the crop has been experimentally evaluated in India. (See Figure 1for area harvested and yield).Growth and developmentBecause pod formation occurs at or just below the soil surface, this cropbenefits from a well-prepared seedbed. The planting density is variableand there seems to be significant plasticity in response to planting density.In Swaziland, five plant densities between 33 000 to 267 000 plant/ha wereinvestigated (Edje et al., 2003). Across this range, the number of pods perplant varied between 40.5 and 5.8. However, there was no effect of theseplanting densities on seed yield.222crop yield response to water