Effect of soil moisture and temperature during fallow on survival of contrasting isolates of arbuscular mycorrhizal fungi

Many arbuscular mycorrhizal (AM) fungal species have worldwide distributions. However, it is not clear whether such species have adapted to local conditions. We compared the responses of mesic temperate and semi-arid tropical isolates of Glomus mosseae and Glomus etunicatum to extremes of temperature and moisture in a pot experiment. Treatments (warm–moist, warm–dry, freeze/thaw–moist, freeze/thaw–dry) were applied to whole soil mycorrhizal inoculum, and their effects were evaluated as both the change in viability of extraradical hyphae and mycorrhizal colonization of bait plants. Moist soil decreased hyphal viability compared with dry soil, irrespective of temperature, but mycorrhizal colonization of bait plants was lower in moist soil only when warm. Frost-heave could have physically ruptured hyphae in the freezing–moist soil without an effect on spores, but parasitism and (or) respiratory depletion of carbon reserves may have reduced survival of all propagules in the warm–moist soil. Hyphae of semi-arid tropical isolates survived all treatments better than hyphae of mesic temperate isolates, but these differences were not reflected in mycorrhizal colonization of bait plants. We found no evidence that these isolates have adapted to local conditions of moisture and temperature. Instead, wide environmental tolerances seem to be present within both populations of these AM fungal species.

Studi Hifa Eksternal CMA dalam Memahami Fungsinya Mengkontribusi Serapan P Tanaman Menggunakan Metode Thin Section

The study of the external hyphae of AMF was conducted for getting data of the soil hyphae distribution from the observation using thin section preparation. The experiment was arranged in factorial fully randomized design. The 1st factors are dosages of P application: 0; 45; 90; 135; and 180 kg ha-1. The second factor was AMF spore inoculation: with inoculation and without inoculation. The observations were conducted to roots and shoots oven dried, absorption of P, P32- fertilizer and P31 from soil. The soil was separated from T-pots and to prepare for making the thin section of soil for observation to hyphae distribution at every 2 cm level. The experiment results showed that the prepared of thin section was documented at the 200 µm x 200 µm (= 40.000 µm2) dimension can be used for external hifas observation. In the 400 µm2 areas of soil without AMF inoculated has about 24 to 27 external hyphal, so at the 40.000 µm2 areas has 2.400 until 2.700 hyphae. The soil was AMF inoculated has 19 to 25 hyphae at 400 µm2 areas of soil, and in the 40.000 µm2 areas has 1.900 until 2.500 hyphae and the length of hyphae about 67-75 m g-1. The diameter hifas at soil without AMF inoculation about 8-10 µm, and at the soil with AMF inoculated has hyphae diameter about 8-11 µm, and the long of hyphae about 53-69 m g-1. The growth speed of hyphae about 0.74-0.89 m day-1 or about 0.031-0.035 m hour-1. The inoculated plant with AMF spore gave more in contribution to P32 fertilizer and soil P31 than that in uninoculated plant, but the yield of shoot and root oven dried was higher for plants without inoculated AMF spore. The inoculated soil with spore of AMF caused to sum of AMF spore and soil P availability was higher than that in uninoculated soil.

Response of Association Vesicular–Arbuscular Mycorrhizal Fungi with Citrus macrophylla W. Rootstock

Citrus macrophylla is an important citrus rootstock for Mexican lemon (Citrus aurantifolia S.). Citrus are highly dependent of vesicular–arbuscular mycorrhizal (VAM) fungi. Four Glomus species were screened for their symbiotic response with C. macrophylla. Seedlings were inoculated with VAM fungi in pots containing sterilized soil. After 3 and 4 months, plants were harvested. Glomus fasciculatum (following by G. intraradices) gave the greatest improvements in growth, resulting in larger plant height and higher shoot dry weight. Glomus aggregatum, G. mosseae, and control plants showed the lowest rates of growth. Plants inoculated with the first three species showed the highest percent of root length colonized. However G. aggregatum gave the highest values of visual density of endophyte in root and soil hyphae. Root colonization and soil hyphae were lowest in plants with G. mosseae.

Viability of an ectomycorrhizal inoculum produced in a liquid medium and entrapped in a calcium alginate gel

Survival of Hebeloma crustuliniforme (Bulliard ex Fries) Quelet, grown in a liquid medium and subsequently entrapped in beads of calcium alginate, was tested under different conditions. Mycelium viability was not affected either by curing the beads for up to 22 h in 0.7 M CaCl2 or by the addition of either peat or bentonite to the alginate gel. Both peat and bentonite improved the water retention of the alginate gel, but only the incorporation of bentonite slowed down the rate at which moisture was lost by evaporation. At 4 °C the entrapped mycelium retained its viability for at least 5 months, provided that storage conditions remained humid. Partial drying of the beads reduced the effective storage time to a month. Emergence of hyphae from the beads was influenced by the presence of sterile soil extracts prepared from a podzolic soil, an acid brown earth, a mesotrophic brown earth, an eutrophic brown earth, and a rendzina. Hyphae grew out of all the beads containing peat irrespective of the type of soil extract but only grew out of those containing bentonite when they were on the mesotrophic brown earth extract. Hyphal emergence from beads containing neither peat nor bentonite appeared to be influenced by the pH of the extract, being better on those that were more acidic. Both sterile and nonsterile nursery soil supported growth of hyphae from the three types of bead, but on nonsterile soil, hyphae were not abundant and those that developed began to die off sooner than those on sterile soil.

Fungal and arboreal biomass in a western Oregon Douglas-fir ecosystem: distribution patterns and turnover

The allocation of biomass and the turnover time of various components were measured from August 1976 to August 1977 in a young, second-growth Douglas-fir stand in the Oregon Coast Range. Allocation of biomass among the tree components was 14 732 kg foliage ha−1, 30 455 kg branches ha−1, 212 941 kg boles ha−1, 49 289 kg nonmycorrhizal roots ha−1, and 15 015 kg host portion of mycorrhizae ha−1. Biomass allocation of fungal components was 10 009 kg mycorrhizal mantles ha−1, 2785 kg Cenococcumgeophilum sclerotia ha−1, 65 kg sporocarps ha−1, 369 kg litter hyphae ha−1, and 6666 kg soil hyphae ha−1. The forest floor was composed of 6970 kg fine (<2 mm) litter ha−1, 6564 kg coarse (2–25 mm) litter ha−1, and 5500 kg log (>25 mm) litter ha−1. Soil organic matter (<0.494 mm) was 87 600 kg ha−1. Total annual stand throughput was 30 324 kg ha−1, excluding soil organic matter throughput. Of this total, 50.5% was accounted for by fungal throughput, 39.5% by tree throughput, and 10.0% by forest floor throughput.