Clonal and Open‐Pollinated Progeny Testing in an Intermediate Wheatgrass Population

Abstract

Efficient testing procedures are needed to identify superior parents for improved cultivars of cross‐pollinated forage species. The primary objective of this study was to compare clonal and open‐pollinated (OP) progeny testing in the selection of parents from an intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & Dewey] population. A second objective was to examine experimental error control from a partially‐balanced lattice design and a nearest‐neighbor analysis relative to a randomized complete block statistical design (RCBD). Parent clones were evaluated in plots that consisted of 30 closely spaced tamers, and progenies were sown in single‐row plots 6.0 m long spaced 0.6 m apart at adjacent sites near Mandan, ND. Based on 3‐yr means from one location, narrow‐sense heritability estimates from 81 parent clones and their respective open‐pollinated progenies averaged 50% for heading date, 45% for plant height, and 69% for dry matter yield. Extreme high‐ and low‐ranked entries for all three traits generally were in common for clonal and progeny tests. A lattice design and nearest‐neighbor analysis reduced experimental error but did not improve rank correlations between parent clones and their progenies or heritability estimates compared with a randomized complete block design. These results suggest that clonal and open‐pollinated progeny tests should be used to select superior parents of intermediate wheatgrass, as both test procedures have unique attributes. Clonal tests are useful in selecting for traits with relatively high heritability, while extensive progeny testing is more appropriate for complex traits such as dry‐matter yield.