1、Citation:Bramley,H.;Ranawana,S.R.W.M.C.J.K.;Palta,J.A.;Stefanova,K.;Siddique,K.H.M.TranspirationalLeaf Cooling Effect Did NotContribute Equally to BiomassRetention in Wheat Genotypes underHigh Temperature.Plants 2022,11,2174.https:/doi.org/10.3390/plants11162174Academic Editor:Daniela TronoReceived:
2、7 July 2022Accepted:18 August 2022Published:21 August 2022Publishers Note:MDPI stays neutralwith regard to jurisdictional claims inpublished maps and institutional affil-iations.Copyright:2022 by the authors.Licensee MDPI,Basel,Switzerland.This article is an open access articledistributedundertheter
3、msandconditions of the Creative CommonsAttribution(CC BY)license(https:/creativecommons.org/licenses/by/4.0/).plantsArticleTranspirational Leaf Cooling Effect Did Not ContributeEqually to Biomass Retention in Wheat Genotypes underHigh TemperatureHelen Bramley1,2,*,S.R.W.M.Chandima J.K.Ranawana1,3,*,
4、Jairo A.Palta1,4,Katia Stefanova1and Kadambot H.M.Siddique11The UWA Institute of Agriculture,The University of Western Australia,Perth,WA 6001,Australia2Plant Breeding Institute,School of Life and Environmental Sciences,The University of Sydney,Narrabri,NSW 2390,Australia3Department of Export Agricu
5、lture,Faculty of Animal Science and Export Agriculture,Uva Wellassa University,Badulla 90000,Sri Lanka4CSIRO Agriculture,Private Bag No.5,Wembley,WA 6913,Australia*Correspondence:(H.B.);chandimauwu.ac.lk(S.R.W.M.C.J.K.R.)Abstract:Hightemperatureandwaterdeficitarethemostcriticalyield-limitingenvironm
6、entalfactorsfor wheat in rainfed environments.It is important to understand the heat avoidance mechanisms andtheir associations with leaf morpho-physiological traits that allow crops to stay cool and retain highbiomass under warm and dry conditions.We examined 20 morpho-physiologically diverse wheat
7、genotypes under ambient and elevated temperatures(Tair)to investigate whether increased water useleads to high biomass retention due to increased leaf cooling.An experiment was conducted underwell-watered conditions in two partially controlled glasshouses.We measured plant transpiration(Tr),leaf tem
8、perature(Tleaf),vapor pressure deficit(VPD),and associated leaf morpho-physiologicalcharacteristics.High water use and leaf cooling increased biomass retention under high temperatures,but increased use did not always increase biomass retention.Some genotypes maintained biomass,irrespective of water
9、use,possibly through mechanisms other than leaf cooling,indicating theiradaptation under water shortage.Genotypic differences in leaf cooling capacity did not alwayscorrelate with Tr(VPD)response.In summary,the contribution of high water use or the leaf coolingeffect on biomass retention under high
10、temperature is genotype-dependent and possibly due tovariations in leaf morpho-physiological traits.These findings are useful for breeding programs todevelop climate resilient wheat cultivars.Keywords:abiotic stress;leaf temperature;morpho-physiological characteristics;water use1.IntroductionCrop pr
11、oductivity under the projected increased intensity and frequency of extremeclimate events,including high temperature,vapor pressure deficit(VPD),and droughtspells,needsgeneticimprovementstargetingspecificenvironmentalconditions.Identifyinggenotypic variability in morpho-physiological responses to en
12、vironmental conditionsand the underlying mechanisms contributing to those variable responses are importantprerequisites for genetic improvement.Wheat is highly sensitive to heat stress 1,2,and increasing air temperature(Tair)threatens wheat production 3,4.High temperatures can negatively affect plan
13、t growthand development and reduce biomass accumulation leading to yield penalties 57.Shortor long-term exposure to high ambient temperatures(35C)can significantly reducewheat yield 8,9 due to accelerated senescence 10,shortened grain-filling duration,re-stricted carbon assimilation 11,pollen steril
14、ity 12,floret abortion 13,and infertility 14.Tolerance to high temperatures has been widely studied and mechanisms identified,es-pecially those supporting better photosynthetic capacity and longer grain-filling periods,Plants 2022,11,2174.https:/doi.org/10.3390/plants11162174https:/ 2022,11,21742 of
15、 22such as stay green 15,16,reduced respiratory O2consumption under day 17 and nightwarming 18,and remobilization of stem reserves 19.Moreover,studies have demon-strated that genetic improvements in heat tolerance can be made through the incorporationof some of these traits from wild relatives of wh
16、eat 15,16.Although improving heat tolerance is clearly important for wheat production,otherstrategies of adaptation may be just as important,but have been less explored 20,21.Forexample,less stress under high temperatures may be experienced through mechanismsthat help prevent overheating,called“heat avoidance”22.Transpiration(Tr)is one suchheat avoidance mechanism through its contribution to leaf cooling 2325.Tris a complexbiophysical process where water evaporates into the surrounding air throu
