Degree Of Mycorrhizal Colonization Research Articles

Comparative effects of four mycorrhizal fungi on loblolly pine seedlings growing in a greenhouse in a Piedmont soil

A greenhouse study was conducted to evaluate the effect of ectomycorrhizae on loblolly pine (Pinus taeda L.) growing in a Piedmont soil. Pine seedlings were inoculated with one of four species of fungi (Scleroderma aurantium, Pisolithus tinctorius, Thelophora terrestris, andRhizopogon roseolus). The seedlings were grown in pots containing a Cecil sandy clay loam amended to create a gradient of extractable P ranging from 5.9 to 52.5 μg/g. After ten months, all colonized seedlings were significantly larger than control seedlings. However, of the four fungi,Scleroderma aurantium mediated a far superior shoot growth response to increasing levels of soil P; the seedlings were significantly larger than those colonized by any other fungus and also had the largest root systems and greatest degree of mycorrhizal colonization.

Differences in Mycorrhizal Colonization of Maize Selections for High and Low Ear Leaf Phosphorus

Mycorrhizal colonization may contribute to the uptake of P in crop plants, particularly under nutrient limited conditions. This study was done to evaluate the hypothesis that inbreds of maize (Zea mays L.) previously selected for differences in ear leaf P at silking, may differ in degree of mycorrhizal colonization. Roots of up to six inbreds (three high P and three low P) were assayed for mycorrhizae after 10 weeks growth under field conditions. A positive rank correlation was observed between ear leaf P content of the inbreds and their percent mycorrhizal colonization. The high P inbreds were more mycorrhizal (18% mean colonization) than the low P inbreds (10% mean colonization). The same six maize inbreds were also grown in the greenhouse under nonmycorrhizal conditions in 1983. Neither tops or roots showed growth or P content characteristics under nonmycorrhizal conditions which would explain the differences observed in the field in ear leaf P content or mycorrhizal colonization. These data suggest mycorrhizal colonization may be a significant component of the genetic differences expressed as ear leaf P content in these maize lines.

Influence of Glomus fasciculatus mycorrhizae on some physical and chemical characteristics of Platanus occidentalis seedlings

Inoculation of Platanus occidentalis seedlings with Glomus fasciculatus significantly increased plant dry weight and foliar phosphorus (P) concentration when compared with the uninoculated control. After 12 weeks inoculated seedlings were 73% taller and 200% greater in total dry weight. The largest dry weight increase was recorded for foliage (212%) followed in order by stem (202%) and root (171%). Averaged overall nutrient treatments, foliar P concentration was 22% greater for the inoculated seedlings. Nutrient regimes representing 1×, 2×, and 4× Hoagland's No. 2 solution and a control significantly influenced seedling height, dry weight, percentage of foliar N, P, and K, and the degree of root colonization. Maximum growth and foliar nutrient concentrations were associated with the 2× Hoagland's nutrient regime followed in order by the 4× and 1× nutrient treatments and the control. Degree of root colonization by G. fasciculatus increased from 42% of the root length in the unfertilized control to 48% at the 1× Hoagland's regime and sharply declined at the 2× and 4× levels. Total dry weight of inoculated seedlings was significantly greater than the noninoculated control at each nutrient level. Incremental differences were 2.71, 4.03, 4.37, and 3.08 g for the control, 1×, 2×, and 4× Hoagland's nutrient regimes, respectively. Seedling growth attributed to G. fasciculatus is directly related to degree of mycorrhizal colonization and inversely related to the amount of extractable soil P.