Báo cáo khoa học: Comparative growth analysis of five first year establishment poplar clones (Populus sp.) grown under a short-rotation intensive culture system

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Báo cáo khoa học: "Comparative growth analysis of five first year establishment poplar clones (Populus sp.) grown under a short-rotation intensive culture system"Comparative growth analysis of five first yearestablishment poplar clones (Populus sp.) grownunder a short-rotation intensive culture systemF. Mau I. ImpensLaboratory of Planty Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium2610Introduction intensive culture is obvious. Clones from and Tacamahaca sections are AigeirosInterest in fast growing poplar clones for well suited for short-rotation intensive cul-maximum production in short-rotation ture because of their rapid juvenile growth.’Fast starter’ clones are most suited for a1-3 yr old coppice stand rotation ac-cording to Zsuffa (1979). Superior hybridgrowth was indicated as a factor respon-sible for the good performance of hybridpoplar in comparison with mere speciesclones (Cain and Ormrod, 1984).Materials and MethodsFive poplar clones: P.x euramericana cv.Robusta; P. trichocarpa cv. Fritzi Pauley; P. tri-chocarpa cv. Columbia River; P. trichocarpa xP. deltoides cv. Beaupr6; P. trichocarpa x P. Primary parameters, such as basal diameterdeltoides cv. Raspalie; were grown from cut- and height, were measured every 2 wk for eachtings planted in a 0.80 x 0.80 m pattern at plot consisting of 81 trees. Height was mea-Afsnee (51 °02’N, 3°39’E; Belgium) in 1987. The sured to an accuracy of 0.5 cm by means of atrees were well irrigated, fertilized and the plots measuring rod and diameter was determined onkept free of weeds. each stem with a vernier caliper 22 cm above Robusta and Columbia River with respec- level. Other parameters, such as num-groundbers of leaves, height of leaf implantation and cm. Robusta ended tively 169 and 180leaf orientation, were monitored on 8 model around Julian date height growth earlytrees of each clone. Leaf development, leaf 261 (Fig.1). ).demography and leaf area distribution were stu-died in relation to aboveground leaf and wood Stem diameter was the largest withbiomass productions. Leaf area was calculated and Raspalje (20 and 22 mm), Beaupréfrom allometric relations between leaf area and while the diameter growth of Robusta hadleaf dimensions. Seasonal growth was alsoanalyzed in terms of relative growth rate already culminated around Julian date 247(RGR), net assimilation rate (NAR) and leaf (Fig. 2).area ratio (LAR) with RGR NAR x LAR. At the =end of the growing season, biomass production Maximum leaf area was reached aroundwas estimated by destructive sampling and Julian date 286, Raspalje and Beaupréweight-surface (leaves) weight-volume or having considerably higher leaf areas(stems) relationships. (about 1 m than the other clones. ) 2 Robusta had the shortest period of leaf retention, in comparison with ColumbiaResults and Discussion River for which 50% of the leaf area was retained until 3 wk later (Fig. 3). Leaf area duration data (Table I) emphasize theStems of Raspalje, Fritzi Pauley, Beaupré large differences among clones.(about 227 cm) were higher than those of The RGR decreased from the beginning Acknowledgmentsof the season, as was also shown by Far-mer (1980), and became negative (leaf study was supported by the I.W.O.N.L. Thisfall) at the end (Fig. 4). The NAR was also ( ...