Studies on the breeding of self-pollinating cereals

The behaviour of 19 varieties of spring wheat under different environmental conditions is discussed in terms of the following five characters: weight per grain, grains per spikelet, spikelets per ear, ears per plant and yield of grain per plant. The first four of these characters (the components of yield) are shown by correlation analyses to be largely independent of each other.Four varieties, chosen because they each showed extreme values of one or more of the components of yield, were crossed in all possible combinations. The F₁ and F₂ of this diallel set of crosses was analysed for each character according to the method of Jinks and Hayman. The results are discussed in relation to crop improvement and predictions are made for each character as to which cross or crosses are likely to be the most profitable for the breeder. The future handling of this material in order to test these predictions is outlined.