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The effect of soil moisture on light interception and the conversion coefficient for three landraces of bambara groundnut (Vigna subterranea)

Published online by Cambridge University Press:  01 September 1999

S. T. COLLINSON
Affiliation:
Division of Agriculture and Horticulture, School of Biological Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK
J. BERCHIE
Affiliation:
Division of Agriculture and Horticulture, School of Biological Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK Present address: Crops Research Institute, CSIR, P.O. Box 3785, Kumasi, Ghana.
S. N. AZAM-ALI
Affiliation:
Division of Agriculture and Horticulture, School of Biological Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK

Abstract

Three landraces of bambara groundnut (Vigna subterranea (L.) Verdc.) were grown as crop stands in controlled environment glasshouses at the Tropical Crops Research Unit, University of Nottingham, in 1995. Two soil moisture treatments were imposed: irrigated to 90% field capacity each week and irrigated to 60% field capacity until establishment (27 days after sowing) with no further irrigation. Seasonal mean fractional interception varied between 0·20–0·37 for the droughted treatments and 0·62–0·74 for the irrigated treatments, resulting in cumulative intercepted radiation of 228–350 MJ/m2 and 662–794 MJ/m2, respectively. The maximum total dry matter (DM) produced was 5·8 t/ha at final harvest (145 days after sowing) with a pod yield of 2·7 t/ha. Under moisture stress there was little difference in DM production between landraces, with the highest total DM of 1·1 t/ha and a pod yield of 0·05 t/ha, representing a harvest index of 0·05 compared with an average of 0·46 for the irrigated treatments. The conversion coefficient was reduced from 1·00 under irrigation to 0·51 g DM/MJ radiation intercepted by soil moisture stress. Two of the landraces showed adaptive mechanisms to avoid drought; these are discussed in relation to maximizing seasonal radiation interception.

Type
Research Article
Copyright
© 1999 Cambridge University Press

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