Heterosis for grain yield and its components in winter by spring wheat hybrids

Abstract

A study of F1 hybrids between hard red winter and hard red spring wheats (Triticum aestivum L.) was conducted to estimate heterosis for grain yield, grain yield components, harvest index, height, and test weight; to note any maternal effects in the expression of heterosis for grain yield, grain yield components, and other agronomic characteristics; and to determine the adaptation of winter by spring wheat hybrids for production in Central and South Texas. Winter by spring wheat hybrids were produced by applying a chemical hybridizing agent on female parents in crossing blocks during the 1984-85 crop season. Twenty-six winter by spring wheat hybrids were evaluated at two locations in the 1985-86 crop season, and 22 additional hybrids were evaluated at one of these locations that same season. Fourteen hybrids at Uvalde and 13 hybrids at Temple (10 the same as a t Uvalde) in the dual location test showed significant high-parent heterosis for grain yield, ranging from 16 to 53 percent at Uvalde and from 16 to 50 percent at Temple. Only two hybrids at Uvalde and three at Temple produced significantly higher grain yields than the best pure line entries in these experiments. In the second test at Temple, 13 of the 22 hybrids showed significant high-parent grain-yield heterosis, with yield advantages ranging from 412 to 655 kg/ha. Six hybrids had significantly superior grain yields to the yield of the best pure line. Kernel weight was the yield component which showed the greatest and most consistent heterosis at both locations. Heterosis generally was greater for grain yield than for individual yield components. Grain yield heterosis appeared to result from a favorable combination of parental yield components. Path coefficient analyses for direct effect and total correlation of individual components on grain yield indicated number of tillers to be contributing the most grain yield variation. All but two of the winter by spring wheat hybrids appeared to be adapted to the Central and South Texas area, at least as far as early maturity and low-vernalization requirements.