No abstract

No abstract

SUMMARYSeedlings from a partial 8 x 8 diallel were propagated and grown at Auchincruive in the west of Scotland and at Invergowrie in the east in order to identify parents which transmit stability for yield and its components and to identify genotypes prone to barrenness.Growth was slower initially at Invergowrie, but once established the plants achieved larger size. Gorella, Cambridge Favourite and 53Q13 transmitted most vigour whilst 60CE5 gave largest numbers of crowns.Site had a major effect on inflorescences per crown, there being 30 per cent less at Invergowrie than Auchincruive. Parents most closely related to wild species (53Q1 3, 60CE5 and Cambridge Favourite) were the most prepotent for high inflorescences per crown. Crosses involving Cambridge Favourite and 53Q13 were the most stable whilst those involving Redgauntlet and Talisman were least stable.Low inflorescences per crown at Invergowrie was partially compensated for by greater numbers of fruits per inflorescence. Site had a minor effect on fruit size. Gorella, Redgauntlet and Talisman progenies gave the largest fruit and 53Q13 the smallest.Close association between stability and inflorescence production simplified selection for stability and, because the effects of site and general combining ability were so much more important than their interactions, selection at either site for adequate inflorescence numbers should ensure stability.Selection should not be unduly influenced by total yield since in unstable types similar yields may be achieved through different pathways. Those which depend on high fruit numbers per inflorescence were unreliable and because of the differences between genotypes it is important to measure the yield components of individual selections.

Nine cultivars and four unnamed seedlings were assessed for their potency as parents in breeding for red core resistance. Field resistance was assessed by scoring the plants for survival on a site heavily infected with Phytophthorafragariae. As a generalisation it was found that the field resistance of the parents was closely related to that of their progenies.The information gained from analysis of data obtained from families raised in routine breeding was at least as useful as that obtained from a diallel cross or from a selfing experiment designed specifically to test the parents.Two unnamed Fragaria virginiana I derivatives (53Q 13 and 60BQ8) and a Siletz derivative (60CE5) were the most resistant and proved to be the most potent sources of resistance, but their fruit quality was poor. Cambridge Favourite, despite its lack of vertical resistance, was at least as potent as Redgauntlet.General combining ability for red core resistance was more important than specific combining ability though the latter was evident with a few of the crosses.

No abstract