Figure 3. Principal component analysis of performance and heat-adaptive traits associated with harvest index (^.....), light interception (- - -), and radiation use efficiency (—) for 25 wheat genetic resource lines grown under hot, irrigated conditions, northwest Mexico, 2003 to 2006. ANT, days to anthesis from emergence; 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; COND, stomatal conductance (flag leaves shortly after anthesis); CTV/CTG, canopy temperature during vegetative and grainfilling stages; HI, harvest index; NDVI, normalized difference vegetative index (used to estimate relative biomass before heading); WI, water index (spectral reflectance index associated with water content of the canopy); YLD, yield.