Differences in Response to Available Phosphorus among White Clover Cultivars
- C. J. P. Gourley ,
- D. L. Allan and
- M. P. Russelle
- E llinbank Dairy Reso Inst., Victorian Dep. of Agric, Warragul South, Victoria, 382Austrilia
S oil Science Dep., 439 Borlaug Hall, Univ. of Minnesota., Minnesota, St. Paul, MN, 55108-6028
l ant Sci. Res. Unit., USDA-ARS-US Dairy Forage Res. Center, Dep. of Soil Science, 439 Borlaug Hall, Univ. of Minnesota, Minnesota, St. Paul, MN, 55108-602
The selection of agriculturally important plant germplasms more tolerant of low P may increase productivity on P deficient soils and reduce P fertilizer requirements. Differences in response to P availability among six cultivars of white clover (Trifolium repens L.) were investigated in a series of pot experiments using a sand-alumina culture technique and two low P soils, an acid Hapludult with 2.6 mg Bray.P kg−1 and a calcareous Calciaquoll with 6.9 mg NaHCO3-extractable P kg−1. Plants were grown in the greenhouse or growth chamber for up to 63 d in solution [P] of 0 to 82 μM. Plant characteristics measured included dry mass and P concentration of shoots, coarse roots, and fine roots; P distribution within the plant; and root traits of total length, root hair length and number per unit root surface area, and root tip number. There were significant differences in shoot dry mass and P accumulation response curves among cultivars; cultivar rankings were consistent in sand-alumina and in soils, but differed from other reports in the literature. We found significant cultivarby-solution [P] interactions when only low vs. high P availabilities were compared, but not when response curves were generated and compared. Differences in herbage yield and P accumulation were associated with larger root systems, but there was no evidence of greater efficiency of P uptake or utilization in these cultivars.
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