title: Stay-green in spring wheat can be determined by spectral reflectance measurements (normalized difference vegetation index) independently from phenology.
abstract: The green area displayed by a crop is a good indicator of its photosynthetic capacity, while chlorophyll retention or 'stay-green' is regarded as a key indicator of stress adaptation. Remote-sensing methods were tested to estimate these parameters in diverse wheat genotypes under different growing conditions. Two wheat populations (a diverse set of 294 advanced lines and a recombinant inbred line population of 169 sister lines derived from the cross between Seri and Babax) were grown in Mexico under three environments: drought, heat, and heat combined with drought. In the two populations studied here, a moderate heritable expression of stay-green was found-when the normalized difference vegetation index (NDVI) at physiological maturity was estimated using the regression of NDVI over time from the mid-stages of grain-filling to physiological maturity-and for the rate of senescence during the same period. Under heat and heat combined with drought environments, stay-green calculated as NDVI at physiological maturity and the rate of senescence, showed positive and negative correlations with yield, respectively. Moreover, stay-green calculated as an estimation of NDVI at physiological maturity and the rate of senescence regressed on degree days give an independent measurement of stay-green without the confounding effect of phenology. On average, in both populations under heat and heat combined with drought environments CTgf and stay-green variables accounted for around 30% of yield variability in multiple regression analysis. It is concluded that stay-green traits may provide cumulative effects, together with other traits, to improve adaptation under stress further.
authors.affiliation: CIMMYT, Mexico, DF, Mexico. m.dasilva@cgiar.org
authors.forename: Marta S
authors.initials: MS
authors.lastname: Lopes
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Reynolds
mesh_terms: D055864:Droughts; D017753:Ecosystem; D006358:Hot Temperature; D008800:Mexico; D010641:Phenotype; D058998:Remote Sensing Technology; D012621:Seasons; D014908:Triticum / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water