Effect Of Mycorrhiza And Fertilizer On Morphology Of The First Order Roots In Fraxinus Mandshurica And Larix Gmelinii Plantation

Manchurican ash (Fraxinus mandshurica) and Davurian larch (Larix gmelinii), two of theimportant forest trees in northeastern China, are infected by vesicular-arbuscular mycorrhizalfungi and ectomycorrhizal fungi respectively. Therefore, this research regarded Manchurianash and Davurian larch plantations as the research species, through the nitrogen fertilizationtreatment, sampling in different seasons and soil depths, studied the relationship betweenmycorrhizal colonization rate and N availability, season and soil depth. Theobjective is toexamine the effects of mycorrhizal fungal infection on root morphology, such as diameter,length and specific root length (SRL), to analyze the effects of nitrogen fertilization treatmenton root morphology, such as diameter, length and specific root length (SRL), and to assess theintegrative impacts of mycorrhizal colonization, fertilization, seasons and soil depths on themorphological attributes in fine roots.The main results show that mycorrhizal fungi infection made the diameter of the firstorder roots of Larch increased significantly (p＜0.001), and made the length (p＜0.001) andSRL (p＜0.001) decreased respectively. Among them, the diameter of ectomycorrhizal fungalinfected and uninfected in unfertilized plots in top soil were: 0.39±0.06 mm and 0.32±0.04 mmrespectively, 0.37±0.03 mm and 0.32±0.02 mm in subsurface soil, 0.41±0.08 mm and0.32±0.02 mm in fertilized plots in top soil respectively, 0.40±0.06 mm and 0.31±0.04 mm infertilized plots in subsurface soil respectively. The mycorrhizal fungi infection made the lengthof the first order roots decreased 23.7％and 24.1％in control and fertilized plots, SRLdecreased 16.3％and 19.3％respectively. VAM fungi infection did not effect the diameter ofAsh, length decreased slightly and SRL decreased significantly (p＜0.05).The diameter of the first order roots in top and subsurface soil in control and fertilizedplots of the two species did not have significant difference (p＞0.05), fertilization decreased thediameter of the first order roots of Ash and Larch (p＞0.05). The length of the first order rootsin top and subsurface soil in control and fertilized plots of the two species did not havesignificant difference (p＞0.05), fertilization increased the length in top soil and decreased thelength in subsurface soil (p＞0.05). The effect of fertilization on the first order roots of Ash andLarch had the same trend with length.Fertilization made the root infection rate decreased significantly in Ash and larchplantation (p＜0.05), Season had significant effect on the root infection rate in Ash and larchplantation (p＜0.05), However, the root infection rate of two species had different seasonalchanges. Summer was higher than spring and autumn, autumn higher than spring slightly inLarch plantation, while the highest in spring, reduced gradually in summer and autumn in Ash plantation. Depth had significant effect on the root infection rate in larch plantation (p＜0.05),while did not have significant effect on the root infection rate in Ash plantation (p＞0.05). Theroot infection rate was higher in top soil than in subsurface soil in Ash and Larch plantation.