Physiological Responses of Wheat Phosphorus‐Efficient and ‐Inefficient Genotypes in Field and Effects of Mixing Other Nutrients on Mobilization of Insoluble Phosphates in Hydroponics

To elucidate the mechanism of mobilization of insoluble phosphates, a field trial and a split root experiment in a growth chamber were conducted. The results showed that a phosphorus (P)-efficient wheat genotype, Yanzhong 144 (YZ), transpired 50% less than a P-inefficient genotype, 80-55. At the grain-filling stage, the free water content in YZ’s rhizosphere was 2.4 times of that of 80-55’s. When either tricalcium phosphate [Ca3(PO4)2] or ferric phosphate (FePO4) were combined with the other nutrients in the same solution, total dry-matter production was 140% greater for Ca3(PO4)2 and 60% greater for FePO4 than when these P sources were each supplied alone to one half of the root system while the other nutrients were supplied to the other half. The excess absorption of cations over anions by the roots facilitated Received 13 September 2006, Accepted 22 October 2006 Address correspondence to Guodong Liu, Tropical Research and Education Center, University of Florida, 18905 SW 280th St., Homestead, FL 33031, USA. E-mail: gliu@ mail.ifas.ufl.edu Communications in Soil Science and Plant Analysis, 38: 2239–2256, 2007 Copyright # Taylor & Francis Group, LLC ISSN 0010-3624 print/1532-2416 online DOI: 10.1080/00103620701549249 2239 D ow nl oa de d by [ U ni ve rs ity o f Fl or id a] a t 0 9: 06 1 4 Fe br ua ry 2 01 4 mobilization of insoluble phosphates. The P-efficient genotype was also water efficient, and the insoluble phosphates TCP and FP were phyto-available in water culture.