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THE RELATIONSHIP OF MYCORRHIZAL INFECTION TO PHOSPHORUS‐INDUCED COPPER DEFICIENCY IN SOUR ORANGE SEEDLINGS *
Author(s) -
TIMMER L. W.,
LEYDEN R. F.
Publication year - 1980
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1980.tb04443.x
Subject(s) - loam , orange (colour) , inoculation , human fertilization , copper , horticulture , phosphorus , copper deficiency , chemistry , phosphorus deficiency , biology , botany , agronomy , soil water , ecology , organic chemistry
SUMMARY In an initial experiment, inoculation of sour orange (Citrus aurantium L.) seedlings in sand with Glomus fasciculatus greatly increased growth with or without fertilization with P or Cu. Application of P or Cu to non‐mycorrhizal seedlings in sand did not stimulate growth. Application of P to non‐mycorrhizal seedlings in a sandy loam soil increased growth, but induced Cu deficiency symptoms and reduced foliar Cu concentrations. Application of P to mycorrhizal seedlings did not induce Cu deficiency symptoms, but reduced foliar Cu concentrations slightly. In a complete factorial experiment, sour orange seedlings in the sandy loam soil, were inoculated with G. fasciculatus or not inoculated, fertilized with 5 levels of P from 0 to 800 mg P 1 ‐1 of soil and 3 levels of Cu from 0 to 8.6 mg 1 ‐1 . Non‐mycorrhizal seedlings, which received no Cu, developed copper deficiency symptoms which were most severe at 200 mg P 1 ‐1 . Copper deficiency symptoms did not appear on the seedlings receiving no P because seedlings failed to grow. Deficiency symptoms disappeared and foliar Cu concentrations increased when seedlings were fertilized with P at 800 mg 1 ‐1 probably because the high rates of P decreased the pH making Cu more soluble. On seedlings inoculated with G. fasciculatus and not fertilized with Cu, increasing rates of P decreased percentage mycorrhizal infection, the number of chlamydospores per g of soil, and the foliar Cu concentrations. Copper deficiency symptoms occurred only at 800 mg P 1 ‐1 and were mild. No Cu deficiency symptoms occurred and foliar Cu concentrations were in the optimum range where Cu was applied. Apparently, P induces Cu deficiency by stimulating growth of non‐mycorrhizal seedlings until Cu becomes the limiting nutrient, whereas, P‐induced Cu deficiency appears to be due to P inhibition of mycorrhizal development on seedlings inoculated with G. fasciculatus.