THE EFFECT OF MYCORRHIZAL FUNGUS ON PHOSPHATE UPTAKE BY CITRUS IN RED EARTH
菌根真菌在红壤中对柑桔吸收磷肥的研究

Inoculation with an endomyeorrhizal fungus (Glomus sp.CC-1)on roots of sunki (Citrus reticulata) and trifoliata orange (Poncirus trifoliata),which are the most useful rootstocks of Citrus in our country,was carried out in pot experiments.The soil used was an nutrient poor especial phosphate deficient red earth,sterilized by autoclave. Seedlings of either species were dealt with four treatments,including soluble and inso- luble phosphate fertilizer application and with or without mycorrhizal inoculation.Each treatment was replicated three pots,consisting of 9 seedlings.Both phosphate fertilizers were labelled with radioactive isotope ~(32)P to examine the absorption of phosphorus by Citrus plants. The present study was undertaken to determine the effects of mycorrhizal infection on P uptake by Citrus seedlings.Microautoradiographs clearly showed that ~(32)P was ta- ken up by hyphae of mycorrhizal fungus and was accumulated in arbuscles and vesicles, inside the roots.Macro-autoradiograph demonstrated that ~(32)P was translocated in shoots of mycorrhizal seedlings much more than it was in nonmycorrhizal seedlings.Phosphorus analysis and seediling growth response indicated that endomycorrhizae increased phos- phate absorption from fertilizer and from soil as well.