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|Title: ||Plant-available P for maize and cowpea in P-deficient soils from the Nigerian Northern Guinea savanna – Comparison of E- and L-values|
|Authors: ||Pypers, Pieter|
Van Loon, Liesbeth
Abaidoo, Robert C.
|Issue Date: ||2006|
|Publisher: ||Plant and Soil|
|Citation: ||Plant and Soil (2006) 283:251-264|
|Abstract: ||There are several indications that legumes are capable of accessing sparingly soluble phosphorus (P) in the soil through root-induced processes. We hypothesize that this plant-induced mobilization of P can be demonstrated if the plant accessible P assessed by isotopic dilution ÇL-value') exceeds the corresponding values assessed in soil extracts ('£-values'). A greenhouse experiment was set up to assess if L/E ratios are affected by P supply and by crop type. The L- and fs-values were determined in three P-deficient soils of the Nigerian Northern Guinea savanna (NGS), applied with various rates of TSP, for two cowpea varieties (Vigna unguiculata L., cv Dan-Ila and cv IT-82D-716) and maize (Zea mays L., cv oba super I) as a reference. Plants grown in control soils were severely P-deficient. Plant growth and shoot P uptake sig nificantly increased with increasing P application in all three soils and for all crops, but relative yield and shoot-P responses to P application were similar between maize and cowpea. Both L- and E-values increased with increasing P application. Average L/E ratios for maize were 1.4 ±0.3 and were unaffected by the P application. For cowpea in contrast, L/E ratios were 3.1 ±0.2 (significantly larger than one) in one of the three control soils and significantly decreased to 1.3 ± 0.1 at largest P supply. Elevated L/E ratios in cowpea were not associated with an increase in P uptake compared to the other two control soils in which no increase in L/E ratio was observed. It is concluded that cowpea is able to access non-labile P under P-deficient conditions. However, this process cannot overcome P deficiency in these soils, probably because P uptake is limited by the small P concentration in the soil solution (1-2 fig P L_1) and this limitation is not overcome by an increase in the accessible soil P quantity (L-value).|
|Description: ||An article published by Plant and Soil (2006) 283:251-264|
|Appears in Collections:||College of Science|
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