Báo cáo lâm nghiệp: "Effect of soil temperature upon the root growth and mycorrhizal formation of white spruce (Picea glauca (Moench) Voss) seedlings grown in controlled environments"

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Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Effect of soil temperature upon the root growth and mycorrhizal formation of white spruce (Picea glauca (Moench) Voss) seedlings grown in controlled environments...

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Nội dung Text: Báo cáo lâm nghiệp: "Effect of soil temperature upon the root growth and mycorrhizal formation of white spruce (Picea glauca (Moench) Voss) seedlings grown in controlled environments"

Effect of soil temperature upon the root growth and mycorrhizal formation of white spruce (Picea glauca (Moench) Voss) seedlings grown in controlled environments D.P. Lavender L. Husted Department of Forest Sciences, University of British Columbia, Vancouver, Canada grown at 3 root zone temperatures: 5-8, 15-17 Introduction 7 and 25-29°C in a growth cabinet programmed for 19-21°C air temperatures, 70-90% RH and an 18 h photoperiod. The root zone tem- The effects of root zone temperature and perature and inoculation treatments were facto- mycorrhizal formation on the shoot and 15 treatment combina- rially arranged give to root morphology of white spruce seedlings tions. were examined in a controlled environ- Seedling height and caliper were measured ment. A companion study evaluated ef- at the initiation of treatment, 5 and 15 wk later. fects of root zone temperature upon root At each sample date, a subsample of seedlings was harvested to estimate needle, stem and growth at different stages of seedling root dry weight, length of long roots, short root growth throughout the year. development and mycorrhizal formation. Mycor- rhizal formation was estimated by scanning the surface of the whole root plugs at 12-40x magnification and checking whole mounts at 500-1000x (Dan!ielson and Visser, 1984). Materials and Methods Treatment means for the 15 wk sample were compared by 2-way least squares analysis of covariance using SYSTAT. Initial caliper, the co- old dormant container-grown white spruce 3 mo not with the variate, did interact significantly from a northern British Columbia seedlings treatments (P>0.80). seed source were inoculated with: 1 ) Hebe- loma crustiliniforme, 2) Thelephora terrestris, 3) Populations of white spruce seedlings grown forest floor collected from a vigorous northern in 313 styroblocks under natural conditions spruce plantation, 4) peat:vermiculite collected commencing in April were placed in controlled from mycorrhizal (mainly E-strain and MRA) environment facilities for 1 mo periods on the container nursery stock, and 5) nothing (con- following dates: 21/9/87, 21/12/87, 16/5/88, trol). After inoculation, the seedlings were 18/7/88. Seedlings were dormant prior to each
trials, but doubtless had different physiologies. interactions between inoculation and tem- maintained out-of-doors before Seedlings were seedling morphol- treatments on perature the first 2 trials; were stored at 2°C in darkness conducted using 3 classes of were ogy for the period Dec 87-May 88, a common B.C. mycorrhizal formation: 1 ) no mycorrhizae, practice; and had recently completed the 2nd yr 2) mycorrhizae formed by T. terrestris and growth flush in July 88. The growth chambers 3) mycorrhizae formed by other fungal were programmed for 14 h daily photoperiods with a constant air temperature of 20°C and soil species. temperatures of 3, 10 and 17°C. Seedling There was no evidence of interactions caliper and shoot length were measured prior to between temperature and mycorrhizal and after the treatment period. The number of actively growing roots greater than 1 cm in class on root or shoot morphology length was recorded when the seedlings were (P >0.50). With two exceptions, root zone harvested. These data were analyzed by temperature accounted for significantly Duncan’s multiple range test for significant more of the variation in root data than did differences at P=0.05 (Table 1). mycorrhizal class. The two exceptions were the number of short roots: 1 ) per unit root dry weight and 2) per unit root length. Root dry weight, length and short root numbers increased (P 0.60). Mycorrhizae formed following all the Mycorrhizal formation by other fungal inoculation treatments at the 15-17°C root species increased the ratio of short roots zone temperature. However, at the 5-8°C produced per unit root dry weight or length root zone temperature, mycorrhizae were (P= 0.02) compared to no or T. terrestris formed only by I terresfris and forest floor mycorrhizae. symbionts (Amphinema-like species and several unidentified ascomycetes); at the Buds were dormant until 1 wk prior to 25-29°C root zone temperature, mycor- final harvest when most flushed, with the rhizae were formed only by T. terrestris flushing rate independent of root zone and E-strain. Accordingly, analyses of temperature or mycorrhizal formation
(P >0.05). Needle dry weight and caliper Discussion and Conclusion increased during the 15 wk experiment with final needle dry weight inversely For most shoot and root parameters, related to root zone temperature. Mycor- temperature accounted for variability more rhizal formation accounted for more of the in the data than did mycorrhizal formation. variability in final caliper than did However, for s;everal parameters (number temperature. The data suggest that cali- of short roots per unit root dry weight per growth was greatest when seedlings length, cs!liper growth), mycorrhizal or were colonized by other species (P = = formation was a more important source of 0.09). variation than temperature. Seedlings with T. terrestris rnycorrhizae or no mycor- The inoculation treatments were 5 rhizae were not significantly different in compared for the 15-17°C root zone these parameters; seedlings with mycor- temperature. Shoot parameters were not rhizae formed by ’other’ species, parti- influenced by inoculation treatments. cularly from the forest floor inoculum, had However, forest floor inoculum increased higher values for these parameters. short root development (P root 0.02), = length (P and weight (P= 0.14) 0.01) = Cold soils are believed to limit white compared to the other treatments (Fig. 1). spruce seedling growth in British Colum- The comparison of mycorrhizal to non- bia. Present data (Table I) demonstrate mycorrhizal seedlings significant was not that current cold storage procedures for any root parameter (P >0.25). exacerbate this situation for a large pro-
portion of planted spruce seedlings. References Earlier data (Lavender, 1988) suggested that a daily photoperiod during cold stor- age could reduce the impact of this Danielson R.M. & Visser S. (1984) Mycorrhizal practice. container-grown conifers in the Pine status of Ridge Provincial Nursery. Annual report submitted to Research Management Division of Alberta Environment, RRTAC. pp. 32-45 Acknowledgments Lavender D.P. (1988) Characterization and manipulation of the physiological quality of planting stock. Proceedings of the Tenth North American Forest Biology Workshop. (Lester for the above research from F.R.D.A. Support D.L. & Worrall J.G., eds.), University of British grants numbers 5-56188 and 5-56191 to D.P. Columbia, Vancouver, B.C. in press Lavender.