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Title: PHOSPHORUS SOURCE, ORGANIC MATTER, AND ARBUSCULAR MYCORRHIZA EFFECTS ON GROWTH AND MINERAL ACQUISITION OF CHICKPEA GROWN IN ACIDIC SOIL

Author
item ALLOUSH, GHIATH
item ZETO, SHEILA
item Clark, Ralph

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2000
Publication Date: 7/4/2000
Citation: Alloush, G., Zeto, S.K., Clark, R.B. 2000. Phosphorus source, organic matter, and arbuscular mycorrhiza effects on growth and mineral acquisition of chickpea grown in acidic soil. Journal of Plant Nutrition 23(9) 1351-1369.

Interpretive Summary: Phosphorus (P) is a major mineral nutrient required by plants that becomes deficient to many plants grown in acidic soils. Beneficial soil fungi called mycorrhiza (AMF) have the ability to enhance growth in acidic soils by making P more available to plants. Experiments were conducted to test the effects of AMF, highly soluble P, relatively insoluble phosphate rock P P(PR), organic matter (OM), and various combinations of these materials to determine effectiveness of treatments on growth and mineral nutrient acquisition of chickpea. Chickpea (a legume) seeds are an important source of protein and nutrients for many people worldwide. Chickpea normally requires applications of readily soluble sources of P to meet growth requirements. Soluble P and AMF alone were not as effective as AMF combined with OM and PR for enhancing plant growth and mineral nutrient (calcium, magnesium, potassium, sulfur, and zinc) acquisition. Combinations of AMF, PR, and OM also inhibited plant acquisition of the toxic elements aluminum and manganese. PR and OM applications to mycorrhizal plants could be low-cost, ecologically sound alternatives to intensive use of P fertilizers for crops grown in acidic soils. Taking advantage of this technology has potential to reduce costs of crop production without sacrificing food quality.

Technical Abstract: Plants grown in acidic soil usually require relatively high amounts of available P to optimize growth, and P may be made available in native soil when roots are colonized with arbuscular mycorrhizal fungi (AMF). In glasshouse experiments, soil treatments of P [0 P (Control), 50 mg soluble- P kg-1 as KH2PO4 (SP), and 200 mg P kg-1 as phosphate rock (PR)], organic matter (OM) at 12.5 g kg-1, AMF (Glomus clarum), and various combinations of these (OM+SP, OM+PR, AMF+SP, AMF+PR, AMF+OM, AMF+OM+SP, and AMF+OM+PR) were added to steam treated acidic Lily soil (Typic Hapludult, pHW = 5.8) to determine treatment effects on growth and mineral acquisition by chickpea (Cicer areitinum L.). The various treatment applications increased shoot dry matter (DM) above the Control, but not root DM. Percentage AMF-root colonization increased 2-fold or more when mycorrhizal plants were grown with AMF, OM+SP and OM+PR. Regardless of P source, plant tacquisition of P, S, Mg, Ca, and K was enhanced compared to the Control, and mineral enhancement was greater in PR compared to SP plants. Mycorrhizal plants also had enhanced acquisition of macronutrients. OM+SP and OM+PR enhanced acquisition of P, K, and Mg, but not Ca. Concentrations of Fe, Mn, Cu, and Al were generally lower than Controls in SP, RP, AMF+PR, AMF+SP, and OM plants, and mycorrhizal plants especially had enhanced micronutrients. Relative agronomic effectiveness values for shoot DM and shoot P, Ca, and Mg contents were considerably higher for PR, including OM+PR, AMF+PR, and AMF+OM+PR, than for SP. PR and OM applications to AMF plants are low-cost, ecologically sound alternatives to intensive use of P fertilizers to crops grown in acidic soil.