Performance of early-generation and modern strawberry cultivars from the University of California breeding programme in growing systems simulating traditional and modern horticulture

Abstract

SummaryEleven strawberry (Fragaria ananassa Duch.) cultivars released by the University of California breeding programme from 1945 – 1966, and nine cultivars released between 1993 – 2004 were evaluated using growing systems with important features of the horticultural practices common during the period of release for each set of cultivars. Values for fruit yield, fruit size, commercial fruit appearance, and fruit firmness, averaged over both horticultural systems, were 47 – 140% greater for modern cultivars than for those released from 1945 – 1966, with the largest increase observed for fruit yield. Differences between early-generation and modern cultivars were highly statistically significant (P < 0.01) for all traits. Comparisons between early-generation and modern cultivars suggest changes for individual traits of 1 – 3% per year. Interactions between cultivar set and horticultural system were statistically significant for plant diameter and fruit yield, but the components of variance for this source explained only 6.0% and 3.1% of the phenotypic variance for these traits, respectively. Genetic differences between cultivar sets explained 34.8% and 74.1% of the phenotypic variance for the same two traits, respectively. These results suggest that the majority of the genetic change obtained by selection for these traits was stable to the most important alterations in horticultural practices over the period evaluated, and provide no indication of any specific adaptation of recent strawberry cultivars to modern horticultural systems.