Lower soil moisture threshold for transpiration decline under water deficit correlates with lower canopy conductance and higher transpiration efficiency in drought-tolerant cowpea

Belko, N and Zaman-Allah, M and Cisse, N and Vadez, V and et al, . (2012) Lower soil moisture threshold for transpiration decline under water deficit correlates with lower canopy conductance and higher transpiration efficiency in drought-tolerant cowpea. Functional Plant Biology. 17 pp.. ISSN 1445-4408

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Abstract

As water availability is critical for reproduction, terminal drought tolerance may involve water-saving traits. Experiments were undertaken under different vapour pressure deficit (VPD) and water regimes (water stress (WS) and well watered (WW)) to test genotypic differences and trait relationships in the fraction of transpirable soil water (FTSW) at which transpiration declines, canopy conductance (proxied by transpiration rate (TR, g H2O cm–2 h–1)), canopy temperature depression (CTD, °C), transpiration efficiency (TE, g kg–1) and growth parameters, using 15 contrasting cowpea (Vigna unguiculata (L.) Walp.) genotypes. Under WW conditions at the vegetative and early podding stages, plant mass and leaf area were larger under low VPD, and was generally lower in tolerant than in sensitive genotypes. Several tolerant lines had lower TR under WW conditions and restricted TR more than sensitive lines under high VPD. Under WS conditions, transpiration declined at a lower FTSW in tolerant than in sensitive lines. Tolerant lines also maintained higher TR and CTD under severe stress. TE was higher in tolerant genotypes under WS conditions. Significant relationships were found between TR, and TE, CTD and FTSW under different water regimes. In summary, traits that condition how genotypes manage limited water resources discriminated between tolerant and sensitive lines. Arguably, a lower canopy conductance limits plant growth and plant water use, and allows tolerant lines to behave like unstressed plants until the soil is drier and to maintain a higher TR under severe stress, as lower TR at high VPD leads to higher TE.

Item Type:	Article
Divisions:	UNSPECIFIED
CRP:	UNSPECIFIED
Uncontrolled Keywords:	canopy temperature depression, drought stress, fraction of transpirable soil water, Vigna unguiculata.
Subjects:	Others > Agriculture-Farming, Production, Technology, Economics
Depositing User:	Mr Siva Shankar
Date Deposited:	28 Mar 2012 09:20
Last Modified:	29 Dec 2016 08:43
URI:	http://oar.icrisat.org/id/eprint/5786
Official URL:	http://dx.doi.org/10.1071/FP11282
Projects:	TLI project, CERAAS (413 Sub-Sahara Africa/A/07/99489)
Funders:	Generation Challenge Programme, Bill and Melinda Gates Foundation, German Academic Exchange Service (DAAD)
Acknowledgement:	The authors thank the senior technicians of crop physiology laboratory of ICRISAT-Headquarters for their technical assistance during the experiments and Ms Rekha Badham for her kind support with the statistical analysis. NB expresses his sincere gratitude and acknowledgement to the German Academic Exchange Service (DAAD) for the In-Regions Scholarship for his PhD program through CERAAS (413 Sub-Sahara Africa/A/07/99489).
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