MORPHOLOGICAL, AGRONOMIC, AND GENETIC CHARACTERIZATION OF S9240 TETRAPLOID CRESTED WHEATGRASS (Agropyron cristaturn)
Mellish, Angus Edward
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Crested wheatgrasses (Agropyron spp.) are forage grasses of importance on the great plains of North America. S9240 crested wheatgrass (Agropyroncristatum (L.) Gaertn.) was produced by using colchicineto double the chromosome number of individuals selected from the diploid, A. cristatum cv. Parkway, followed by several cycles of selection for height,seed size, floret fertility,and forage yield. Some introgression of tetraploid A. cristatum cv. Kirk germplasm occurred during the selection cycles. The goals of this study were to compare seed characteristics, emergence, height, crown width, tiller density, tiller weight and tiller angle of S9240 with those of other crested wheatgrass cultivars,both diploid and tetraploid, and to estimate the heritability of plant height and crown diameter of two S9240 populations. In addition, ananalysis of the relationships among selected species and populations from the genus Agropyron was carried out using AFLP markers. Morphological data were collected from a number of sward-seeded and spaced-planted trials during the summers of 1999 and 2000. Emergence trials were conducted in the greenhouse. AFLP analysis was conducted on bulks and individuals from selected Agropyron lines to determine relationships and levels of variance within and among populations. The mean seed weight and total seed yield of S9240 were significantly (p<0.05) greater than those of other tested crested wheatgrass cultivars. Heavier seeds had higher emergence relative to light seeds within cultivars, but bulked S9240,which had the highest mean seed weight,did not have superior emergence levels compared to other cultivars. In general S9240 was taller,narrower crowned and had fewer, heavier, more upright tillers than other crested wheatgrass cultivars. Plant height and crown diameter were moderately to highly heritable characteristics in a population of S9240. Even though the majority of molecular variance occurred within populations it was possible to differentiate among all tested populations using AFLP markers. Most populations were grouped as expected from previous taxonomic analyses, but some populations may requirere classification based on the results of this study.