The Effect of Heterosis on Yield Components in Hybrids of Wheat

Plant hybridizers of the past have found definite increases in yield and vegetative growth of F1 plants intraspecific and interspecific crosses. In more recent times, the successful utilization of hybrid vigor in cross-pollinated crops regulated by sterility systems has stimulated the search for usable sterility systems in cereal grains. In wheat which is self-pollinated, this method of improving yield has recently become possible with discovery of male sterility and fertility restoring mechanisms. It has often been observed that certain varietal or line combinations will produce more desirable progeny than others. Therefore, it is essential that information be obtained on sources of good germ plasm in wheat. Such information will help the breeder obtain desired results from a hybridization program with minimum labor. Little work has been done to measure components of yield of F1 hybrids and parents in wheat and the magnitude of expression of heterosis that occurs in the F1. In the present investigation, 57 crosses and their parents were studied to determine the effect of heterosis on components if yield. A supplementary study was run to determine the effect various spacing distances between plants within a unit area had upon the expression of heterosis for the various yield components.