Restriction of transpiration rate under high vapour pressure deficit and non‐limiting water conditions is important for terminal drought tolerance in cowpea
- 23 July 2012
- journal article
- Published by Wiley in Plant Biology
- Vol. 15 (2), 304-316
- https://doi.org/10.1111/j.1438-8677.2012.00642.x
Abstract
Drought stress is a major constraint on cowpea productivity, since the crop is grown under warm conditions on sandy soils having low water-holding capacity. For enhanced performance of crops facing terminal drought stress, like cowpea, water-saving strategies are crucial. In this work, the growth and transpiration rate (TR) of 40 cowpea genotypes with contrasting response to terminal drought were measured under well-watered conditions across different vapour pressure deficits (VPD) to investigate whether tolerant and sensitive genotypes differ in their control of leaf water loss. A method is presented to indirectly assess TR through canopy temperature (CT) and the index of canopy conductance (Ig). Overall, plants developed larger leaf area under low than under high VPD, and there was a consistent trend of lower plant biomass in tolerant genotypes. Substantial differences were recorded among genotypes in TR response to VPD, with tolerant genotypes having significantly lower TR than sensitive ones, especially at times with the highest VPD. Genotypes differed in TR response to increasing VPD, with some tolerant genotypes exhibiting a clear VPD breakpoint at about 2.25 kPa, above which there was very little increase in TR. In contrast, sensitive genotypes presented a linear increase in TR as VPD increased, and the same pattern was found in some tolerant lines, but with a smaller slope. CT, estimated with thermal imagery, correlated well with TR and Ig and could therefore be used as proxy for TR. These results indicate that control of water loss discriminated between tolerant and sensitive genotypes and may, therefore, be a reliable indicator of terminal drought stress tolerance. The water-saving characteristics of some genotypes are hypothesised to leave more soil water for pod filling, which is crucial for terminal drought adaptation.Keywords
This publication has 38 references indexed in Scilit:
- A conservative pattern of water use, rather than deep or profuse rooting, is critical for the terminal drought tolerance of chickpeaJournal of Experimental Botany, 2011
- New phenotyping methods for screening wheat and barley for beneficial responses to water deficitJournal of Experimental Botany, 2010
- Terminal drought-tolerant pearl millet [Pennisetum glaucum (L.) R. Br.] have high leaf ABA and limit transpiration at high vapour pressure deficitJournal of Experimental Botany, 2010
- Transpiration response of ‘slow-wilting’ and commercial soybean (Glycine max (L.) Merr.) genotypes to three aquaporin inhibitorsJournal of Experimental Botany, 2009
- Constitutive water-conserving mechanisms are correlated with the terminal drought tolerance of pearl millet [Pennisetum glaucum (L.) R. Br.]Journal of Experimental Botany, 2009
- Thermal infrared imaging of crop canopies for the remote diagnosis and quantification of plant responses to water stress in the fieldFunctional Plant Biology, 2009
- Seedling Stage Drought‐Induced Phenotypes and Drought‐Responsive Genes in Diverse Cowpea GenotypesCrop Science, 2008
- Physiological traits and cereal germplasm for sustainable agricultural systemsEuphytica, 2006
- A multicystatin is induced by drought‐stress in cowpea (Vigna unguiculata (L.) Walp.) leavesFEBS Letters, 2004
- Leaf Temperature and Transpiration of Field Grown Cotton and Soybean under Arid and Humid ConditionsPlant Production Science, 2002