ACID SOIL TOLERANCES OF WHEAT LINES SELECTED FOR HIGH GRAIN PROTEIN-CONTENT

Literature suggests that nitrogen (N) metabolism is involved in differ ential acid soil (Al) tolerances among wheat (Triticum aestivum L. en Thell) genotypes. Atlas 66 wheat is characterized by acid soil and alu minum (Al) tolerance, nitrate (NO3(-)) preference, pH increase of the rhizosphere, high nitrate reductase activity, and high protein in the grain. Atlas 66 has been used as a high protein gene donor in the deve lopment of new high protein wheat lines at Lincoln, NE. The objective of our study was to determine the acid soil tolerances of such lines a nd to relate such tolerances to their abilities to accumulate grain pr otein when grown on near-neutral, non-toxic soils. Twenty-five experim ental lines, nine cultivars not previously classified as Al-tolerant o r -sensitive and three cultivars previously classified according to ac id soil tolerance, were grown for 28 days in greenhouse pots of acid, Al-toxic Tatum subsoil. Relative shoot dry weight (pH 4.35/pH 5.41%) v aried from 83.2% for Atlas 66 to 19.3% for Siouxland. Atlas 66 was sig nificantly more tolerant to the acid soil than all other entries excep t Edwall. Yecorro Roja and Cardinal were intermediate in tolerance. No ne of the high protein lines approached Atlas 66 in tolerance, but two lines (N87U106 and N87U123) were comparable to Cardinal (relative sho ot yield = 54%) which is used on acid soils in Ohio. At pH 4.35, the m ost acid soil tolerant entries contained significantly lower Al and si gnificantly higher potassium (K) concentrations in their shoots than d id sensitive entries. Shoots of acid soil sensitive entries, Scout 66, Siouxland, Plainsman V, and Anza contained deficient or near deficien t concentrations of K when grown at pH 4.35. Acid soil tolerance was n ot closely related to calcium (Ca), magnesium (Mg), phosphorus (P), ma nganese (Mn), or iron (Fe) concentrations at pH 4.35. Liming the soil to pH 5.41 tended to equalize Al and K concentrations in shoots of tol erant and sensitive entries. Results indicated that acid soil toleranc e and grain protein concentrations were not strongly linked in the whe at populations studied. Hence, the probability of increasing acid soil tolerance by crossing Atlas 66 with Nebraskan wheat germplasm is low. However, the moderate level of acid soil tolerance in N87U106 and N87 U123 (comparable to that of Cardinal) may be useful in further studies .