Báo cáo lâm nghiệp: Growth, mineral nutrient content and nitrogen metabo- ism in Laccaria laccata-inoculated and non-inoculated Douglas fir seedlings during their growth period

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Báo cáo lâm nghiệp: " Growth, mineral nutrient content and nitrogen metabo- ism in Laccaria laccata-inoculated and non-inoculated Douglas fir seedlings during their growth period" nitrogen metabo-Growth, mineral nutrient content andlism in Laccaria laccata-inoculated and non-inoculatedDouglas fir seedlings during their growth periodM. Chalot, B. Botton J. BanvoyUniversité de Nancy I, Facult6 des Sciences, Laboratoire de Physiologie Végétale et Forestibre,BP 239, 54506 Vandœuvre-Iès-Nancy, France needles and roots were removed immediatelyIntroduction after collection for amino acid, protein and enzyme determinations. Aspartate aminotrans- ferase (AAT) activity was determined spectro-Enhanced caused by ecto- plant growth photometrically and proteins were measured inoculation in the nursery ismycorrhizal using a colorimetric method. Amino acids were analyzed using an HPLC procedure. Total Nwell documented: thus Laccaria strains was measured by a microKjeldahl method, totalhave proven to be very efficient for im- P by a colorimetric method and K and Mg byproving growth of various conifers (Le atomic absorption spectrophotometry.Tacon and Bouchard, 1986). The investi-gations described herein were carried outto obtain information on physiological andbiochemical modifications that can explain Resultssuch stimulation. The present study com-pared the seasonal changes in proteinand amino acid levels, aspartate amino- the end of the growing period, L. lac- Bytransferase activity and nutrient content in cata-inoculated seedlings were significant-both L. laccata-inoculated and non-inocu- ly higher (not shown) and had accumulat-lated Douglas fir grown in a forest nursery. ed more than 2-fold the fresh matter of the controls (Table I). In expanding shoots, N, P, K and Mg concentrations decreased rapidly until mid-August (Fig. 1 A, B, C, D) and tended to increase after growthMaterials and Methods ceased. No significant difference was found in nutrient analysis of stems andAfter 1 yr of growth in the nursery, 12 seedlings roots between treated and untreatedfrom both untreated and treated plots were col- plants (not shown). By contrast, statistical-lected at random, bimonthly from May to Sep- ly significant (ANOVA, P 0.05) changes =tember. Root and top fresh weights and heights were observed for leaf nutrient analysiswere measured for each seedling. Parts of thebetween treatments and, more particularly, Concerning protein amounts and AATby the end of the growing season (Fig. 1A, activity levels, high and significant differ- ences (ANOVA, P 0.05) were found inB, C, D). =foliar analysis between inoculated seed- As a hypothesis, we might propose thatlings and controls: leaves of inoculated lower AAT activity combined with a higherDouglas fir accumulated higher protein proline amount in non-inoculated Douglasamounts (Fig. 1 F) and showed greater fir characterized seedlings in stress-induc-AAT capacities (Fig. 1 E). By contrast, ing situations. AAT is often considered asthere was no difference in root analysis an indicator of physiological activity inbetween treatments (Fig. 1 E, F). plants affected by various internal or ex- ternal factors (Cooper and Hill-Cofting- Alanine, aminobutyri ...