Seed Size and Seedling Vigor in Crested Wheatgrass 1

ONE of the major causes of failure to establish stands of crested wheatgrass [Standard, Agropyron desertorum (Fisch.) Schult., and Fairway, A. cristatum (L.) Gaertn.] can be attributed to planting seed at too great a depth. Most seedlings do not have sufficient vigor to emerge and become established when the seed is planted more than 1 to l$/2 inches deep. The development of varieties with greater seedling vigor should help to reduce this hazard. Not only could seed be planted deeper where moisture conditions are generally more satisfactory for germination but more vigorous seedlings would have a better chance to break through soil crusts that often form at the surface after planting. At shallower depths these seedlings would also be more likely to survive because of more rapid development of both top and root growth. They should more easily overcome the hazards of establishment such as damage from root rots, insect damage, hail, sand blast, weed competition and other growth limiting factors. The development of varieties that can be planted with greater assurance of stands should result in an increase in the acreage planted to crested wheatgrass. One of the major objectives of the grass breeding program with crested wheatgrass at the U. S. Northern Great Plains Field Station is the development of varieties with increased seedling vigor. The most direct approach has been the selection toward heavy or large seeded types. The results of experiments showing the relationship between seed size