水稻-固氮粪产碱菌内根际体系的探讨

 水稻接种固氮粪产碱菌后，可清晰看到细菌紧密地附着在稻根的表面。扫描电镜观察结果表明:其主要分布区域为根系的伸长区和根毛区，根尖端分生区内侧较少。从冰冻断裂的根横剖面中发现，进入稻根内的细菌成蔟地存活于外皮层、皮层大通气腔、直至中柱维管组织中。大约有0.01%-0.1%附着于根表的粪产碱菌进入根内，多数存在于细胞间隙中，少量进入根细胞内，在根内的粪产碱菌仍可以繁殖。粪产碱菌进入根内的途径可能是通过根表皮细胞间隙和根毛基部。粪产碱菌同样也存在于淹水茎内。接种量的多少与菌在水稻植株中的数量、水稻的长势及植株重量呈正相关。与整体根系相比，研碎后的根系具有较高的乙炔还原活性，且根系的乙炔还原活性显著高于茎段的活性。

STUDIES ON RICE-NITROGEN FIXER ALCALIGENES FAECALIS ENDORHIZOSPHERIC SYSTEM

Scanning electron microscopy of rice (Oryza sativa L.) root inoculated with Alcaligenes faecalis A15H revealed massive adsorption of bacterial cells to root surface, and less adsorption to root tip. Heavy colonization on root elongation and root hair zones could be seen. In the cross-section of frozen-fractured rice root, the Alcaligenes faecalis bacteria were found in the outer cortex, lysigenous space, stele and secondary xylem, which colonized mainly in the intercellular space.Among them about 0.05%-0.1%can entered into root cells.Penetration by bacteria probably occured at epidermal cell junction and basal part of the root hair. Some bacteria may penetrate further inside the root giving a microbial continuum from epidermal to stele.The presence of bacteria in the flooded stem interior was also observed.The number of bacteria adsorpted to the root surface, entered into the root and the growth rate and fresh weight of rice plant were proportionated to the concentration of inocula.In comparison of root system, the acetylene reducing activity (ARA) was increased significantly after the releasing of A.faecalis from the root interior.The ARA however, of root system was higher than that of flooded stem.