Specific Adaptation and Genetic Progress for Grain Yield in Great Plains Hard Winter Wheats from 1987 to 2010

摘要: A previous investigation, using region-wide data from Great Plains wheat (Triticum aestivum L.) breeding trials, indicated a possible plateau in the rate of genetically determined yield potential. Data same USDA- Agricultural Research Service (ARS) coordinated long-term regional performance nurseries was used to further examine genetic improvement winter wheats specifi c agroecological or production zones over time period 1987 2010. The absolute grain all entries and top fi ve most productive increased majority this period. relative improvement, obtained by comparing yields those control cultivar Kharkof, ranged not signifi cantly different zero 1.98% yr –1 . This change, however, statistically cant (α = 0.05) only two 12 evaluated. Variance components identifi ed zone locations within as being largest sources variation yields. due either genotype × environmental factors remained both constant 24-yr small, variances. Genetic progress for enhanced region might be limited magnitude these variances constraints arising continuous evolution pest pathogen populations.