The Effect of Maturity on the Viability and Longevity of the Seeds of Western Range and Pasture Grasses 1

N recent years there has been a considerable demand for grass I seeds of both native and introduced species for reseeding in the West. The variation in types of seeds, in seeding habits of the species needed, and the lack of experience in handling the seeds of many of the species has resulted in various problems, not only to those interested in commercial seed production, but also to those engaged in grass research. One of these problems is the amount of shattering before or during the harvesting process which depends on the species, weather conditions, and harvesting methods. The possibility suggested itself that perhaps losses due to shattering might be avoided by harvesting before the seeds were fully ripe. This study was made to determine the earliest stage in development a t which seeds of Agropyron cristatum (L.) Gaertn., crested wheatgrass ; A. smithii Rydb., western wheatgrass ; A. trachycaulum (Link) Malte, slender wheatgrass; Bromus inermis Leyss, smooth brome; E. marginatus Nees., mountain brome; B. polyanthus Scribn. ; Elymus glaucus Buckl., blue wildrye; and Stipa viridula Trin., green needlegrass, could be harvested without loss in viability, longevity, and vigor of the seedlings following germination. Shattering had previously been observed in all of these species with the exception of B . inermis . Most of the investigations dealing with seed maturity in the grass family have been carried out on the small grains and corn. Lehmann and Aichele (6)3 have reviewed most of these studies, as well as those dealing with forage grasses. In general, it has been found that the seeds of members of the Gramineae will germinate and produce seedlings when harvested as early as the milk stage of development. Harlan and Pope (2) found that five out of seven barley varieties produced viable seeds as early as 6 days following pollination. In a study on the time of cutting as related to the production of viable seeds, Gill (I) found that Hordeurn nodosum and Bromus mollis produced viable seeds when cut in the milk-ripe condition. Hermann and Hermann ( 3 ) conclude from germination and emergence tests of seeds of Agropyron cristatum collected at IO stages of maturity, from pre-milk to fully mature, that “vigorous plants probably cannot be expected from seed harvested earlier than in the hard dough stage.” They found, however, that good germination could be obtained from seeds harvested in the early dough stage.