Grain Fill Duration In Twelve Hard Red Spring Wheat Crosses: Genetic Variation And Association With Other Agronomic Traits

The rate and duration of grain rill period has been shown to be associated with increased yield in cereals when water deficits occur during maturation. Grain fill duration can be approximated as the time between heading date and physiological maturity, allowing measurements to be obtained for large breeding populations. Our objectives were to determine the genetic variation for grain fill duration, and to determine its association with agronomic traits in a set of spring wheat (Triticum aestivum L.) crosses. Fifty F-3.5 progenies from 12 spring wheat crosses plus parents were grown in replicated trials in three Montana environments. Heritabilities were consistently high across crosses for grain protein (mean = 0.92) heading date (mean = 0.89) and test weight (mean = 0.79), intermediate for physiological maturity (mean = 0.64) and grain yield (mean = 0.59) and lowest for grain fill duration (mean = 0.4). Earlier heading and later physiological maturity were associated with longer grain fill across crosses. Earlier heading also was often significantly correlated with higher grain protein concentration and higher test weight, but usually was not associated with grain yield. Longer grain fill duration was usually associated with higher grain protein in two environments, but with lower grain protein for the cool, wet environment. Grain fill duration showed no significant association with grain yield in most instances. Selection for early heading in early generations followed by selection for grain yield and grain fill duration in later generations using multi-location trials may circumvent the negative association between grain yield and grain protein.