Second generation progenies (M2) derived from crosses using barley pollen irradiated at 500, 1,000 1,500 and 2,000 rads increasingly resembled the maternal parent. 'Golden Promise', but contained some characteristics derived from the paternal parent, 'Magnum'.

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Results from two trials on spring barley varieties are presented. A factorial fertilizer trial estimated the effects of N, P and K at each of three levels on diastatic power, heat-stable alpha-amylase activity, grain nitrogen content, thousand corn weight and yield in a single variety. This revealed that the main effect of N was the most important source of variation. In a subsequent variety-nitrogen trial seven varieties were tested at each of three levels of N.In the variety-nitrogen trial, diastatic power was found to be positively correlated with both grain nitrogen content and alpha-amylase activity although these latter two variates were not themselves correlated. These observations were confirmed both within genotypes and within environments, and a hypothesis is advanced in explanation.The implications of the results for a breeding programme directed towards the production of high-yielding, high-diastase varieties are discussed.

SUMMARYAs part of a study of the relationship between plant development and grain yield, winter and spring barleys were sown in the autumn and spring. Apical development and leaf area development were monitored and the final yield was partitioned into grain weight and grain number. The photosynthetically active radiation (PAR) absorbed was calculated.The main differences found were between sowings rather than between genotypes within sowings. The autumn sowing outyielded the spring sowing because the grains were heavier, although the autumn sowing tended to have fewer grains m‐2. In the autumn sowing the rate of initiation of spikelet primordia was slower, due to the lower temperatures encountered, but the initiation phase lasted longer and a larger proportion of primordia survived. However, the increased proportions of tillers to mainstem reduced the mean number of grains/ear.The numbers of grains m‐2 and the yield were related to the PAR absorbed. In this analysis the earlier anthesis of the autumn‐sown plants could be seen to be reducing the PAR absorbed and consequently the grains m‐2.

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