Genetic variation and heritability of phosphorus uptake in Alamo switchgrass grown in high phosphorus soils

Developing crop cultivars with high P uptake may prevent the accumulation of phosphorus in the soil and its escape to streams and water reservoirs. The purpose of this investigation was to assess the potential for P uptake in switchgrass (Panicum virgatum L.), an important bioenergy and forage crop, and to determine the nature of genetic variation and heritability of this trait. Thirty genotypes from a population of 'Alamo' switchgrass were evaluated in the greenhouse [Tifton loamy sand (fine, loamy, siliceous thermic Plinthic Paludults)] and the field [Wedowee coarse sandy loam (fine, kaolinitic, thermic family of the Typic Kanhapludults)] at a rate of 450 mg P kg−1 and 200 mg N kg−1 soil. Significant genetic variation was observed among the parental genotypes for P concentration, biomass production, and P uptake. Genotype × location interaction was significant for all three traits. Nevertheless, rank correlation of the genotypes between the two locations was high for P uptake (r = 0.83, P < 0.01) indicating that little of the genotype × location interaction is associated with changes in ranking. Narrow sense heritability based on individual plant and family means were 2 and 13% for P concentration, 60 and 69 for biomass production, and 67 and 73 for P uptake, respectively. Expected genetic gain based on individual plant selection were <1, 51, and 65% of the parental means for P concentration, biomass production, and P uptake, respectively. Expected gain from selection based on half-sib progeny testing was slightly higher (2, 55, and 68% for P concentration, biomass, and P uptake). Although little gain from selection is predicted for P concentration, the magnitude of heritability values for biomass production and P uptake indicate that substantial genetic progress in increasing P uptake can be achieved through breeding for higher biomass production.