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Transpiration Sensitivity to Evaporative Demand Across 120 Years of Breeding of Australian Wheat Cultivars
Author(s) -
Schoppach R.,
Fleury D.,
Sinclair T. R.,
Sadok W.
Publication year - 2017
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/jac.12193
Subject(s) - transpiration , vapour pressure deficit , cultivar , agronomy , trait , crop , biology , yield (engineering) , water use efficiency , plant breeding , environmental science , horticulture , botany , photosynthesis , irrigation , materials science , computer science , metallurgy , programming language
Historically, wheat yields in drought‐prone Australian environments have been consistently increasing for over a century. There is currently an agreement that approximately half of that increase is attributable to breeding programmes, but their physiological basis remains poorly documented. In this investigation, we hypothesized that limited whole‐plant transpiration rate ( TR ) under high atmospheric vapour pressure deficit ( VPD ) could result in advantageous water conservation and crop yield increase under south Australian conditions. Therefore, TR response to VPD was measured in the 0.9–3.2 kPa range for a group of 23 wheat cultivars that were released from 1890 to 2008. Consistent with a water‐conservation hypothesis, all genotypes displayed a VPD break point ( BP ) in TR with increasing VPD such that TR was limited at VPD above a BP of about 2 kPa. The BP and slope of TR with increasing VPD above the break point were correlated with the year of release, although the changes were in different directions. Such changes in these transpiration parameters were independent of plant leaf area and only marginally correlated with Zadok's stages. These results indicated that selection over 120 years by breeders for yield increase unconsciously resulted in genotype selection for the expression of the limited‐ TR trait.