HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Reynolds, M. P. Articles by Condon, A. G. PubMed Articles by Reynolds, M. P. Articles by Condon, A. G. Agricola Articles by Reynolds, M. P. Articles by Condon, A. G. Related Collections Water Stress Crop Physiology & Metabolism Wheat Temperature Stress

Evaluating Potential Genetic Gains in Wheat Associated with Stress-Adaptive Trait Expression in Elite Genetic Resources under Drought and Heat Stress

^a CIMMYT, Int. Apdo. Postal 6-641, 06600 México, D.F., Mexico; A.S.I. Saad, ARC, Wad Medani, Sudan
^b CSIRO, Plant Industry, GPO 1600, Canberra, ACT, 2601, Australia. M.P. Reynolds secondary address: ACPFG, Adelaide, Australia

^* Corresponding author (m.reynolds{at}cgiar.org).

While genetic resources provide an invaluable gene pool for crop breeding, the majority of accessions in germplasm collections remain uncharacterized and their potential to improve stress adaptation is not quantified. A selection of 25 elite genetic resources for wheat (Triticum aestivum L.) were characterized for agronomic and physiological trait expression in drought- and heat-stressed environments. Under drought, the physiological traits best associated with yield were canopy temperature, associated with water uptake, and carbon isotope discrimination, associated with transpiration efficiency. Under heat stress stomatal conductance, leaf chlorophyll content, and canopy temperature (associated with radiation use efficiency in this environment) were well correlated with yield. Theoretical yield gains based on extrapolating the best trait expression to the highest yielding backgrounds were also estimated. Under drought, the best expression of canopy temperature and carbon isotope discrimination suggested potential yield gains of approximately 10 and 9% above the best yielding cultivars, respectively; under heat stress, canopy temperature and remobilization of stem carbohydrates suggested potential yield gains of approximately 7 and 9%, respectively. Other physiological trait expression was associated with potential yield gains to varying degrees. When considering agronomic traits, the best expression of harvest index suggested yield gains of approximately 14 and 24% in drought and hot environments, respectively, while the combined best expression of both harvest index and final aboveground biomass suggested yield gains of 30 and 34%, respectively. Principal component analysis indicated that many of the physiological traits that were associated with yield and biomass were not strongly associated with each other, suggesting potential cumulative gene action for yield if traits were combined. When comparing trait expression across drought and hot environments, several physiological traits (e.g., canopy temperature) showed closer association with each other than did performance traits, supporting the idea that such stress-adaptive traits have generic value across stresses.

Abbreviations: ANT, days to anthesis • BM, dry aboveground biomass at maturity • BMA, biomass shortly after anthesis • CHL, flag leaf chlorophyll shortly after anthesis • CHO, soluble carbohydrate content of stems shortly after anthesis • CID, carbon isotope discrimination of well-watered leaves • COND, stomatal conductance (flag leaves shortly after anthesis) • CT, canopy temperature • CTV/CTG, canopy temperature during vegetative/grainfilling stages • GEI, genotype by year interaction • HI, harvest index • LI, light interception • nBM, dry aboveground biomass at maturity normalized by maturity date • nBMA, biomass shortly after anthesis normalized by anthesis date • NDVI, normalized difference vegetative index (used to estimate relative biomass before heading) • OA, osmotic adjustment between well-watered and drought-stressed leaves • PCA, principal component analysis • RARSc, ratio analysis of reflectance spectra to estimate carotenoid pigments in the canopy • RUE, radiation use efficiency • TE, transpiration efficiency • TGW, thousand grain weight • WI, water index (spectral reflectance index associated with water content of the canopy) • WU, apparent water use based on gravimetric soil measurement • WUE, water use efficiency • WUEa, apparent water use efficiency (biomass/WU) • YLD, yield

Received for publication April 10, 2007.