Morphology, Cytology, and Fertility of Agropyron podperae and its Hybrids with A. intermedium1

Abstract

Seventy‐three collections of wheatgrass (Agropyron podperae Nabel.) from two sites in Iran were grown at Logan, Utah to determine the morphological, cytological, and reproductive characteristics of this rarely collected taxon. The A. podperae collections were morphologically similar to those of A. intermedium (Host) Beauv., except that A. podperae was caespitose (tufted) and A. intermedium was rhizomatous. Sixty‐nine of 71 A. podperae plants were 2n=42, and the other two were 2n=41 and 43 Agropyron podperae behaved meiotically as a segmental autoallohexaploid and averaged 0.23I, 20.58II, 0.01III, 0.14IV, 0.002VI, and 0.002VIII per cell in 487 metaphase‐I cells. Most plants were moderately to completely self‐sterile; some (11%) were highly self‐fertile.Agropyron podperae hybridized readily with A. intermedium, with 56% crossing success. Chromosome pairing was almost complete in the F1 hybrids, which averaged 1.17I, 18.57II, 0.27III, 0.68IV, 0.02V, 0.02VI, and O.OO1VII per cell in 681 metaphase‐I cells. The chromosomes of A. podperae differed from those of A. intermedium by structural rearrangements, primarily interchanges. The hybrids produced 10 to 75% stainable pollen and averaged 44%. Although A. podperae does not appear to have much direct potential as a forage grass, it may serve as a useful secondary gene pool for A. intermedium and Triticum aestivum L.The morphological, ecological, geographical, and cytogenetic differences that separate A. podperae from A. intermedium are on the order of those that distinguish subspecies. It is proposed that A. podperae be relegated to a subspecies of A. intermedium, i.e., A. intermedium (Host) Beauv. subsp. podperae (Nabel.) Dewey comb. nov.