Genetic and Physiological Evaluation of Yield and Other Important Traits of Hard Red Winter Wheat in the Texas High Plains.

A population of 124 F₆ recombinant inbred lines (RIL) was developed from a cross between TAM 112 and TAM 111, two widely planted hard red winter wheat cultivars in the U.S. Southern High Plains.  The RIL population was planted in dryland locations at Bushland (BD) and Chillicothe (CH), TX and under 40%, 50%, 65%, 75%, and 100% potential evapotranspiration (PET) at Etter (ET), TX during the 2011 and 2012 cropping seasons.  Yield and its components, and some physiological traits were measured among the 124 RILs. The mean grain yield from dry locations (BD, CH, 40% and 50% PET) ranged from 604.7 to 1142.2 kg/Ha while those in the 75% and 100% PET ranged from 3735.8 to 4206.1 kg/Ha in 2011.  The yield correlations among BD, CH, and 100% PET were significant (r = 0.18 – 0.30, P < 0.05).  Heading dates of RILs were negatively associated with yield while height was positively associated yield at the dry environments (BD, 40%, 50% and 65% PET) in 2011. Biomass data collected from BD, 50%, and 100% PET showed that total biomass, heads/m², and HI were highly correlated with yield from BD (r = 0.53, 0.25, and 0.26). Heading date was negatively associated with biomass, TKW, HI at dryland conditions (BD and 50%).  An S2000 miniature Fiber Optic Spectrometer was used to measure the absorbance, reflectance and transmission of light of the plant canopy at grain filling stage.  Calculated indices were highly and significantly correlated with yield at 100% (r = 0.36 – 0.51) and at BD (r = 0.18 – 0.36).  The RILs showed transgressive segregation for all traits, including yield, heading date, height, dry biomass, thousand kernel weight (TKW), heads/m², and harvest index (HI) across all locations and water levels.  The estimated heritability of these traits ranged from 0.13 to 0.80.  The data from 2012 will be analyzed and included.  This preliminary data showed significant variations among the RILs thus this population may be valuable to map QTL associated with yield and drought tolerance traits in the Texas High Plains.