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  • Author or Editor: Cecil T. Pounders x
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A statistical model was used to partition the effects of age group, cutting position within the plant crown, and ramet environment on propagule development from stem cuttings collected from random stock plants of Ilex ×attenuata Ashe `Foster #2' (`Foster' holly). Most of the intra-clonal variation observed originated from sources not partitioned by the model. Small differences in growth were associated with sampling position within the crown. Repropagation gave no indication that factors measured by the model could be passed from ramet to propagule. Within-clone variation was not reduced by repropagation or by hedging propagules to force new growth.

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Analysis of clonal variation for two rooting traits of western hemlock [Tsuga heteterophylla (Raf.) Sarg.] clones indicated that realized genetic gain would be improved by more effective partitioning and reduction of environmental differences associated with clones. Interactions between clones and multiple propagation dates were significant, but clone rank changes between dates were minor. Number of meted cuttings per plot (RC) and number of main roots per cutting (MR) were more highly correlated genetically (1.06) than phenotypically (0.36). Broad-sense heritabilitiesHx 2 = 0.62 and Hx 2 = 0.79 for RC and MR, respectively) and predicted genetic gain from clonal selection were moderately high. Both the percentage of rooted cuttings and root system quality could be rapidly improved by the clonal selection procedures used.

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This study reports on the performance of 34 clones of crapemyrtle (Lagerstroemia indica L., L. fauriei Koehne, and L. indica × L. fauriei hybrids) grown in field plots at four locations representative of different environments in the southeastern United States. Traits evaluated were spring leaf-out and initiation of flowering in the second season after field planting and plant height after 3 years of growth. Cluster analysis (Ward's method) was used for grouping and comparison of means across locations for each trait. Best linear unbiased prediction was used for estimating random effects in linear and generalized linear mixed models 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. L. 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 that were evaluated. First flowering was affected by environmental variation more with interspecific hybrids than with L. fauriei and L. indica clones. Performance, particularly with respect to plant height, of several clones did not agree with previously published classifications. Information generated by this study will allow crapemyrtle breeders, landscape professionals, and consumers to better select the most appropriate crapemyrtle clone for a particular application.

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