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Phosphorus acquisition and wheat growth are influenced by shoot phosphorus status and soil phosphorus distribution in a split-root system

Ma, Q. and Rengel, Z. (2008) Phosphorus acquisition and wheat growth are influenced by shoot phosphorus status and soil phosphorus distribution in a split-root system. Journal of Plant Nutrition and Soil Science, 171 (2). pp. 266-271.

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Root proliferation and greater uptake per unit of root in the nutrient-rich zones are often considered to be compensatory responses. This study aimed to examine the influence of plant phosphorus (P) status and P distribution in the root zone on root P acquisition and root and shoot growth of wheat (Triticum aestivum L.) in a split-root soil culture. One compartment (A) was supplied with either 4 or 14 mg P (kg soil)-1, whereas the adjoining compartment (B) had 4 mg P kg-1 with a vertical high-P strip (44 mg kg -1) at 90-110 mm from the plant. Three weeks after growing in the split-root system, plants with 4 mg P kg-1 (low-P plants) started to show stimulatory root growth in the high-P strip. Two weeks later, root dry weight and length density in the high-P strip were significantly greater for the low-P plants than for the plants with 14 mg P (kg soil)-1. However, after 8 weeks of growth in the split-root system, the two P treatments of compartment A had similar root growth in the high-P strip of compartment B. The study also showed that shoot P concentrations in the low-P plants were 0.6-0.8 mg g-1 compared with 1.7-1.9 mg g-1 in the 14 mg P kg -1 plants after 3 and 5 weeks of growth, but were similar (1.1-1.4 mg g-1) between the two plants by week 8. The low-P plants had lower root P concentration in both compartments than those with 14 mg P kg -1 throughout the three harvests. The findings may indicate that root proliferation and P acquisition under heterogeneous conditions are influenced by shoot P status (internal) and soil P distribution (external). There were no differences in the total root and shoot dry weight between the two P treatments at weeks 3 and 5 because enhanced root growth and P uptake in the high-P strip by the low-P plants were compensated by reduced root growth elsewhere. In contrast, total plant growth and total root and shoot P contents were greater in the 14 mg P kg-1 soil than in the low-P soil at week 8. The two P treatments did not affect the ratio of root to shoot dry weight with time. The results suggest that root proliferation and greater P uptake in the P-enriched zone may meet the demand for P by P-deficient plants only for a limited period of time.

Item Type: Journal Article
Publisher: WILEY-VCH Verlag
Copyright: © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
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