Phosphate Uptake and Arbuscular Activity in Mycorrhizal Allium cepa L.: Effects of Photon Irradiance and Phosphate Nutrition

摘要: The effect of photon irradiance on phosphate uptake and growth onion plants was investigated in an experiment aimed at determining whether development activity mycorrhizal infection arbuscules are linked to physiological effects. Mycorrhizal (inoculated with Glomus mosseae (Nicol. & Gerd.) Gerdemann Trappe) non- Allium cepa. L. were grown three soil levels two irradiances (410 190 µmol m-2 s-1). There one harvest 6 weeks. Data obtained for (specific rate), plant (total active by trypan blue staining succinate dehydrogenase (SDH) respectively). a positive response the lower P (P0 P1) but not P2 high irradiance. This smaller low Furthermore, data root/shoot fresh-weight/dry-weight ratios indicated that allocation dry matter altered accord their increased demand photosynthate. Reduced associated rates all treatments, greatest P0 P1. These reductions incidence or intensity nor arbuscules. At reduced under irradiance, within infected regions roots remained same as other treatments. use nitroblue tetrazolium chloride vital stain SDH showed during 6-week period experiment, revealed physiologically active. Branched (counted freehand sections fresh roots) always had alkaline phosphatase activity. Thus, young plants, observations gives good indication amount infection. may be so older roots.