title: The severity of iron chlorosis in sensitive plants  is related to soil phosphorus levels.
abstract: BACKGROUND
  Iron (Fe) deficiency chlorosis, a major nutritional problem in plants growing on calcareous soils, is related to the content and reactivity of soil iron oxides and carbonates. The effects of other soil components, however, need elucidation. In this paper we tested the hypothesis that application of high doses of phosphorus (P) to the soil can aggravate Fe chlorosis.
  
  
  RESULTS
  Lupin and sorghum were grown on 24 calcareous soils. Leaf chlorophyll concentration (LCC) in lupin decreased with increasing available P/available Fe ratio in the native soil but LCC in sorghum was unaffected by that ratio. Application of P to the soil resulted in significant reduction of LCC and dry weight in lupin. In sorghum, LCC and dry weight were positively affected by P fertilisation for soils poor in available P whereas the opposite effect was generally observed for the P-rich soils. In another experiment where olive plants were pot-grown on two soils during the 2009–2011 period, P fertilisation affected LCC negatively only in 2009 and 2011 and in the soil that was poorer in iron oxides.
  
  
  CONCLUSIONS
  Application of fertiliser P to Fe chlorosis-inducing soils is likely to aggravate this deficiency. However, this effect depends on the plant and the Fe and P statuses of the soil.
authors.forename: Antonio Rafael
authors.initials: AR
authors.lastname: Sánchez-Rodríguez
authors.forename: María Carmen
authors.initials: MC
authors.lastname: del Campillo
authors.forename: José
authors.initials: J
authors.lastname: Torrent
mesh_terms: D002130:Calcium Phosphates / Q000378:metabolism / Q000506:poisoning*; D002734:Chlorophyll / Q000032:analysis / Q000096:biosynthesis; D060467:Disease Resistance; D005290:Ferric Compounds / Q000032:analysis / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D005308:Fertilizers / Q000633:toxicity*; D007501:Iron / Q000032:analysis / Q000378:metabolism; D000090463:Iron Deficiencies; D031297:Lupinus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D031658:Olea / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism / Q000633:toxicity; D010935:Plant Diseases / Q000139:chemically induced* / Q000517:prevention & control; D018515:Plant Leaves / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D011897:Random Allocation; D012987:Soil / Q000737:chemistry*; D012995:Solubility; D045868:Sorghum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013030:Spain; D013045:Species Specificity
chemical_list: D002130:Calcium Phosphates; D005290:Ferric Compounds; D005308:Fertilizers; D012987:Soil; D002734:Chlorophyll; C000499:ferric oxide; D010758:Phosphorus; C494370:calcium phosphate, monobasic; D007501:Iron