Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 23, 2009
Publication Date: February 1, 2010
Citation: Pounders Jr, C.T., Blythe, E.K., Fare, D.C., Knox, G.W., Sibely, J.L. 2010. Crapemyrtle genotype × environment interactions and trait stability for plant height leaf-out and flowering. HortScience. 45(2):198-207. Interpretive Summary: Crapemyrtle varieties have not been widely tested to determine how variations in the growing environment affect traits such spring leaf-out, initiation of flowering and growth rate. Thirty-four commonly grown varieties of crapemyrtles were tested at sites in Alabama, Florida, Mississippi and Tennessee to determine if varieties reacted to changes in growing conditions as reflected in changes in the three listed traits. We found that changes in the growing environment affected season of flowering more than spring leaf-out and growth rate in the majority of varieties. We also refined the classification of the expected leaf-out, first flower and landscape size of tested varieties. Information generated by this study will help landscape professionals and consumers select the most appropriate crapemyrtle variety for a particular application.
Technical Abstract: This study reports on the performance of thirty-four clones of crapemyrtle growing at four sites representative of environmental differences in the southern U.S. Traits evaluated include spring leaf-out, initiation of flowering and 3-year plant height. Best linear unbiased predictors (BLUP) were used for estimating random effects in a mixed model to better determine the general performance of the clones under a variety of environmental conditions. Each clone’s trait stability was quantified using the regression of an individual genotype’s performance for each of the three studied traits on an environmental index based on the trait mean for all genotypes grown in an environment. Sequence of clone leaf-out and size rankings were more stable across the environments than the sequence in which the various clones initiated flowering. Lagerstroemia fauriei clones and clones originating from the initial cross between L. indica and L. fauriei were generally later to leaf out, earlier to flower, and more vigorous growers than L. indica or the complex L. indica × L. fauriei clones which were evaluated. Performance, particularly growth, of several clones did not agree with previously published classifications. Since this study was conducted in multiple environments and subjected to more rigorous statistical standards, consideration should be given to updating crapemyrtle references widely used by the landscape industry in the South.