Variability of the levels of P, K, Ca and Mg in annual lespedeza

Six cultivars and four breeding lines of annual lespedeza (Lespedeza striata, L. stipulacea L.) were grown during the summer of 1971 at Knoxville, Crossville, and Martin, Tennessee, to evaluate the possibility of inherited variability in accumulation of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg). Whole-plant samples were harvested, in some cases for the three stages of growth approximating prebloom, full bloom, and early seed formation. Phosphorus, K, Ca, and Mg concentrations were determined from the nitric-perchloric acid digestate using the Technicon Autoanalyzer.

Concentrations of P, K, Ca, and Mg were found to be significantly different among genotypes revealing the existence of genetic mechanisms controlling accumulation levels of these elements in the annual lespedeza species. The type of results obtained led to speculation that the genetic control mechanisms, at least for P and Ca, are multigenic.

A significant location x genotype interaction occurred indicating that differences in concentrations among genotypes were altered by the effect of different environments upon the expression of the genetic mechanisms controlling concentration.

Generally, K, Ca, and Mg concentrations decreased as the plant matured, but P seemed to remain relatively constant.

Commercial Korean was relatively high in P, Ca, and Mg but medium in K. Ark 226-10 was low in relative concentration for all four elements. Kobe was low in relative concentration of P and K but high in Ca and Mg.

Generally, a positive relationship existed between P and K, and between Ca and Mg. Potassium was negatively correlated with Ca and with Mg.