Provenance Impacts Transplant Establishment and Adventitious Root Regeneration of Sycamore

Autor: Fred T. Davies, Larry J. Shoemake, Michael Arnold
Rok vydání: 2004
Předmět:
Zdroj: Journal of the American Society for Horticultural Science. 129:360-367
ISSN: 2327-9788
0003-1062
DOI: 10.21273/jashs.129.3.0360
Popis: A series of six experiments was conducted over eight years to investigate impacts of provenance on transplant establishment in landscapes and the role of adventitious root regeneration in differential genotypic responses during establishment of Platanus occidentalis L. Fall, spring, and summer transplants of container-grown half-sib families (HSF = seedlings derived from a single mother tree with unknown male parentage), including two selections native to Brazos County, Texas (Brazos-C, Brazos-D), one native to Cookeville, Tenn. (Cookeville), two Kentucky/Tennessee HSF from the Westvaco Corp. (WV-10, WV-14), and two Texas HSF from the Texas Forest Service tree improvement program (TFS-09, TFS-24), were established to determine fi eld/landscape growth responses. Subsequent studies were conducted to investigate differential leaf gas exchange responses of TFS-09 and Cookeville during moderate water defi cits and to determine root regeneration potential (RRP) responses of TFS-09, Brazos-C, WV-14, and Cookeville HSF following fall, spring, and summer transplant. To investigate consistency of within-family genotypic responses and to determine relationships among adventitious root initiation from shoot cuttings, RRP, and landscape establish- ment, fi ve seedlings of TFS-09 and fi ve from Cookeville HSF were clonally propagated and ramets tested under fi eld and RRP conditions similar to those with seedling-derived plants. Regionally native HSF consistently grew taller, had larger trunk diameters, and often had greater survival during the fi rst 3 years in the landscape than HSF not native to the region in which the studies were conducted. Rapidity of root regeneration among HFS at the time of transplant was the best root growth related predictor of successful landscape establishment. Some growth advantages were found using genetically improved HSF, but not as consistent an improvement as with the use of seedlings from regional prov- enances. Within-family variation in landscape performance was greater with nonregional Cookeville clones than with regional TFS-09 clones, however there was overlap among the more vigorous Cookeville clones and the least vigorous TFS-09 clones. Increased rapidity of root regeneration and drought adaptations related to leaf morphology and gas exchange characteristics may be involved in enhanced growth responses of Texas regional genotypes. No consistent relationships were found among adventitious rooting responses from shoot cuttings and subsequent RRP of the same genotypes from root tissues or their growth during the fi rst 3 years in landscapes. Establishment of landscape trees is diffi cult in the southwestern United States as favorable planting conditions are of limited dura- tion (Arnold, 2002). Drought and heat typically limit establishment from late spring to late fall, while excess soil moisture can hinder winter and early spring transplanting. Winter temperatures may fl uctuate from those favorable to growth (20 to 25 °C) during the day to well below freezing at night. Although many of the same species utilized in the eastern United States are often grown in southwestern nurseries, their performance in the nursery and landscape is variable (Arnold, 2002). Ecotypic or within-species variation has been reported for numerous forest trees, and this variation has been successfully exploited for greater biomass ac- cumulation, improved disease/pest resistance, straighter trunks, increased height, and/or more desirable branching patterns for several forest species (Zobel and Talbert, 1984; Zobel et al.
Databáze: OpenAIRE
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