接种彩色豆马勃对模拟酸沉降下马尾松幼苗生物量的影响

Effects of ectomycorrhizal fungi (tinctorius ( Pers.) Coker & Couch) on the biomass of masson pine (Pinus massoniana) seedlings under simulated acid rain

外生菌根能够提高宿主植物对外界环境胁迫的抵抗力,促进植物的生长,试图揭示外生菌根对酸雨胁迫下马尾松生长的保护作用。采用盆栽试验,共设置4个处理:酸雨对照处理((CK),约pH值5.6)不接种,酸雨对照处理接种,酸雨pH值3.5处理不接种,酸雨pH值3.5处理接种。pH值3.5的酸雨处理降低马尾松的生物量,在试验前期降低根冠比,试验中后期则提高根冠比,在试验初期增加了叶面积,但中后期显著降低了叶面积。接种外生菌根菌有利于马尾松幼苗的生长,pH值3.5处理下接种外生菌根菌能提高马尾松幼苗的生物量,外生菌根菌对生物量分配和叶面积的影响与酸雨胁迫的影响是相反的,即外生菌根菌抵消了酸雨胁迫对马尾松的影响。

Tree growth is a result of multiple, interacting, physiological processes influenced by an inherited genetic constitution and the ambient environment. The growth of coniferous trees is closely connected with the amount of nitrogen and other nutrients available. Air pollutants that limit carbon gain or nutrient availability may suppress growth rate and total biomass production, and thus affect the nutrient allocation pattern. An increase in the acidity of precipitation predisposes tree seedlings to a number of environmental stresses; these are reflected in seedling germination, growth, and survival. Decreased growth has been seen in response to sulfate-eontaining precipitation. However, considerable differences have been reported in the responses of conifer species to acid rain. Many tree species in forest ecosystems live in symbioses with ectomycorrhizal （ECM） fungi, which provide their hosts with nutrients. Symbioses with ECM fungi are therefore very important. Soil acidification due to dry and/or wet deposition can inhibit the uptake of minerals and water essential for plant growth, and increase the uptake of toxic metals, due to poor differentiation by root meristems. However, colonization by ectomycorrhizal fungi can increase the uptake of essential nutrients and water, and reduce the toxicity of metals such as Al2＋ and Mn2＋. To evaluate the effects of ectomycorrhizal colonization on the growth of Pinus massoniana Lamb seedlings grown in acidified soils, we grew masson pine seedlings with ectomycorrhizae for 210 days in acidified forest soil originating from Chongqing Municipality, Southwest China. There were two acid treatments; one at pH 3.5 and the control at about pH 5.5, and two ectomycorrhizal treatments （inoculated, non-inoculated）. Simulated acid rain in combination with pH 3.5 reduced seedling biomass. Inoculation with ectomycorrhizal fungi was able to increase seedling biomass. Treatment time, acid treatment, and ectomycorrhizae all had remarkable effects on biomass, and we observed interacting effects between treatment time and acid treatment, and between acid treatment and ectomycorrhizae. Treatment time had significant effects on root, stem, and leaf biomass allocation, and acid treatment and ectomycorrhizae had obvious effects on root and leaf percentages. There were interactions between and among treatment time, acid treatment, and ectomycorrhizae. Under simulated acid rain （pH 3.5）, the root-shoot ratio initially decreased and then increased. Treatment time and acid treatment had significant effects on the root-shoot ratio, while the ectomycorrhizae showed no effect. We observed interacting effects on the root-shoot ratio between acid treatment and treatment time, treatment time and ectomycorrhizae, and among these three. Compared with the control （pH 5.5）, simulated acid rain （pH 3.5） initially increased leaf area, and then significantly reduced leaf area. Treatment time, acid treatment, and ectomycorrhizae had obvious effects on specific hemi-surface area, and there were also significant interactions among these factors. The effects of ectomycorrhizae on biomass allocation and leaf area was opposite to the effects of acid rain. Inoculation with ectomycorrhizal fungi encouraged the growth of masson pine seedlings , and increased specific hemi-surface area, enhancing photosynthesis and elevating biomass accumulation. Ectomycorrhizal fungi were thus able to counteract the effects of simulated acid rain, and protect the growth of the masson pine seedlings. It may be that ectomycorrhizal fungi can be used effectively to increase plant resistance to acid rain in places such as Southwest China.