Genetic and environmental effects on rooting ability of dormant unrooted hybrid poplar cuttings

Abstract

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Use of Belowground Growing Degree Days to Predict Rooting of Dormant Hardwood Cuttings of Populus

“…We believe our GDD-based thermal index and its inclusion as a classification variable for belowground GDD in our model allowed us to isolate substantial variation associated with environmental error. Our broad-sense heritability estimates of 0.15 and 0.19 for root dry weight and number of roots, respectively, were greater than previous field studies (H < 0.10) (ZALESNY, 2003;ZALESNY et al, 2003); however, the heritability estimates from most previous studies that were conducted in growth chambers and greenhouses were greater than ours because environmental error was further reduced (H from 0.15 to 0. 80, FARMER et al, 1989;H from 0.36 to 0.56, WILCOX and FARMER, 1967;H > 0.80, YING and BAGLEY, 1977).…”

“…Our phenotypic correlations corroborated those of previous studies (ZALESNY, 2003;RIEMENSCHNEIDER and BAUER, 1997). We agree with RIEMENSCHNEIDER and BAUER (1997) that only a few easily measured dependent variables need to be studied to learn about the aboveground and belowground growth of the cuttings without losing substantial biological information.…”

“…The ability of poplars to form adventitious roots is therefore critical to the commercial deployment of intensively cultured poplar plantations (DICKMANN, 2001;STANTURF et al, 2001). Rooting is often genotype-dependent (ZALESNY et al, 2003;YING and BAGLEY, 1977;CUNNINGHAM, 1953); however, the success of plantation establishment also depends on the influence of genotype x environment interactions (HEILMAN et al, 1994;HAISSIG et al, 1992). Belowground environmental conditions such as soil temperature, moisture, strength, and aeration influence the success of rooting from dormant hardwood cuttings (DESROCHERS et al, 2002;RHODENBAUGH and PALLARDY, 1993;WIERSUM, 1980).…”

“…A poplar-rooting index based on belowground GDD is obtained by summing the daily belowground GDD during the period from planting until harvesting. Soil temperature data have been converted to belowground GDD in an attempt to identify planting windows that promote rooting, based on the genotype being used (ZALESNY, 2003). The identification of such planting windows for specific combinations of genotypes and belowground GDD could increase the success of plantation establishment, which ultimately could reduce pressure on native stands of aspen.…”