Phosphorus Uptake from Rhizosphere Soil by Two Wheat Cultivars

Inorganic soil phosphorus extractable with sodium bicarbonate (NaHCO3-Pi), soil pH and root hairs length and density in the rhizosphere of two winter wheat cultivars (Triticum aestivum L. cv. Shichun,Sleipner) grown on a high pH Chinese silt loam (52.7 mg NaHCO3-Pi kg-1) and a Danish sandy loam (43.4mg NaHCO3-Pi kg-1) were studied to assess how these wheat cultivars differed in phoephorus uptake.The rhizosphere soil pH of two wheat cultivars grown on the two soils were fairly unchanged with increasing distance from the root surface. However the root hairs of Shichun were 2.1 times longer than those of Sleipner. Root surface area (RSA) of Shichun increased by 192% due to root hairs whereas root hairs of Sleipner increased RSA by 68% only. Hence the root system of Shichun was in contact with more soil than that of Sleipner, even though Sleipner had a longer root. Grown at the lower pH and level of NaHCO3-Pi in the Danish soil Shichun absorbed more inorganic phosphorus than Sleipner whereas at the higher pH and level of NaHCO3-Pi in the Chinese soil there was no phosphorus uptake difference between the two wheat cultivars.