a1 ODA Microclimatology Group, School of Agriculture, Sutton Bonington, Loughborough, Leicestershire, England
a2 International Crops Research Institute for the Semi-Arid Tropics, Patancheru PO, Andhra Pradesh 502324, India
Four genotypes of groundnut grown with limited irrigation in a medium depth Alfisol in Central India transpired similar total amounts of water (220–226 mm) over the season, but produced different amounts of shoot dry matter (390–490 g m−2). The extraction front of Kadiri 3 moved most rapidly down the soil profile which may have enabled it to maintain the fastest rates of transpiration when soil water depletion was greatest. Tap root extension rates of Kadiri 3 in the first 32 days after sowing were also the fastest. NC Ac 17090 was more efficient than the other genotypes in extracting water immediately after irrigation from the upper 40 cm of the soil, but this had little value in determining the pattern of water availability in this experiment. Differences in the water extraction characteristics of these genotypes explain little of the variation in dry matter:water ratio, and do not account for the major variation in harvest index associated with drought.
(Accepted September 18 1987)
p1 Present address: Oxford Forestry Institute, Oxford University, South Parks Road, Oxford, England.
† Submitted as Journal Article No. 657 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).