International Crops Research Institute for the Semi-Arid Tropics
Abstract
Since major cultivation areas of chickpea (Cicer arietinum
L.) are in the arid and semi-arid zones, terminal drought
is one of the major constraints limiting its productivity.
Simple analytical crop models can help in identifying key
strategies to improve the chickpea productivity under
drought. For example, Passioura (1977) had proposed
that the yield is a function of transpiration, transpiration
efficiency (TE) defined as the biomass production per
unit of water transpired, and harvest index. As improvement
of TE means maximization of crop production per unit of
water use, it is one of the important components for
improving the drought resistance (Turner et al. 2001).
Although TE had been recognized as a highly relevant
trait, so far very little research effort had been made
towards field screening for it, especially due to the
difficulties in measuring TE in any screening method.
The method developed by Farquhar et al. (1982) for
estimating TE through measuring the discrimination
against 13C by leaves during photosynthesis, and
establishment of a close relationship between the carbon
isotope discrimination (δ13C) and TE in many legume
crops such as bean, cowpea, groundnut, and soybean has
provided an useful method of screening. This gave scope
for using δ13C as an indirect screening tool for TE. In
chickpea, however, there is no information available on
the relationship between δ13C and TE. The major
objectives of this study were to check if there are any
variations available for δ13C, to investigate the relationship
between δ13C and TE, and to ascertain the possibility of
using δ13C as a surrogate for TE measurements
