P uptake by plant Some are strongly upregulated when phosphate supply is inadequate. Other phosphate systems are constitutive which are not affected by changes in phosphate concentration in the nutrient medium The ph in the apoplast controls the H2PO4 the uptake rate
• Some are strongly upregulated when phosphate supply is inadequate. Other phosphate systems are constitutive which are not affected by changes in phosphate concentration in the nutrient medium. • The pH in the apoplast controls the H2PO4 - the uptake rate. P uptake by plant
PATTERN OF P UPTAKE BY SPRING BARLEY 06 205 P04 03 2 a 110 130 50 19o Number af days aner sowing Sovrce Adapted am Lagh a /asiAn 7sBS Jre uptake of pastors arges cuming crop growh Spring barkey arrypy supplier wth prasporur took中abo3.4a6相Ppa orange fine whereas a cop wah lithe avaiLabl pnoepwus took up abort o 4 kg P O (0.2 kg P)ne per dty (bnu fine). Mieko af graw reflected pfaasporars wvaabrlirx 64 ad 2.9 wr wieh and wtrxo am adequate suppy o phosphorus
Role of mycorrhizae in P uptake Many plants have associations have a symbiotic relationship with mycorrhizae The plants supply mycorrhizae with C and the mycorrhizae supply the plant with nutrients 2. Mycorrhizae may increase P uptake by 3-5 times No mycorrhizae With mycorrhizae
1. Many plants have associations have a symbiotic relationship with mycorrhizae The plants supply mycorrhizae with C and the mycorrhizae supply the plant with nutrients. 2. Mycorrhizae may increase P uptake by 3-5 times. Role of mycorrhizae in P uptake
Transport of phosphorus in plant P adsorbed from the roots is transported in the xylem to young leaves. The xylem contains mostly inorganic P P can also be transported from older leaves to younger leaves - and from the shoots to the roots-in the phloem. The process is known as re-translocation The phloem can contain both organic and inorganic P So the P is remobilization in plant
– P adsorbed from the roots is transported in the xylem to young leaves. The xylem contains mostly inorganic P. – P can also be transported from older leaves to younger leaves – and from the shoots to the roots – in the phloem. The process is known as re-translocation. – The phloem can contain both organic and inorganic P. – So the P is remobilization in plant. Transport of phosphorus in plant
Regulation of P uptake The concentration of phosphate cycled in phloem from shoot to root acts as a feedback signal to regulate P uptake(Drew and Saker 1984) High concentrations of phosphate in the phloem induced by low demand in shoot repress uptake Conversely low concentration associated with high shoot demand stimulate uptake
Regulation of P uptake • The concentration of phosphate cycled in phloem from shoot to root acts as a feedback signal to regulate P uptake (Drew and Saker 1984). • High concentrations of phosphate in the phloem induced by low demand in shoot repress uptake. Conversely low concentration associated with high shoot demand stimulate uptake