The seed production capabilities of five species of cool‐season grasses as influenced by three row spacings and three nitrogen rates were determined for a 5‐yr period. The conclusions here are based on the 4‐ or 5‐yr cumulative average seed yields. Kentucky bluegrass produced more seed in 30‐ and 60‐cm rows. Crested wheatgrass and smooth bromegrass seed production was higher in 60‐cm rows, but for smooth bromegrass the difference in seed yield for the 60‐cm rows was not significantly higher than those of the 90‐cm rows. Orchardgrass produced more seed in the 90‐cm rows. Row spacing did not influence the seed yields of red fescue. Kentucky bluegrass and orchardgrass responded with more seed when fertilized with nitrogen at 90 or 112 kg/ha. Crested wheatgrass produced more seed with 112 kg/ha of nitrogen, but the differences were only significant in the 4‐yr average yields. Nitrogen rates over 67 kg/ha did not increase the seed yields of red fescue and smooth bromegrass. The 90‐cm rows resulted in heavier seed than that produced in 60‐ and 30‐cm rows. The 112 kg/ha of nitrogen increased seed weight in red fescue, but decreased seed weight of smooth bromegrass. Nitrogen rates did not influence the weight of crested wheatgrass seed.

Postharvest residue burning, a standard practice in grass seed production in the Pacific Northwest, may be restricted because of concerns for air quality. This research compares the effects of burning with those of mechanical residue removal on red fescue (Festuca rubra L.), smooth bromegrass (Bromus inermis Leyss.), and crested wheatgrass [Agropyron desertorum (Fisch. ex Link.) Schult.]. The experiments were conducted on a silt loam soil (Pachi Ultic Haploxerolls) as a split‐plot within each grass species. Main plots were three levels of 18‐10‐10‐7 fertilizer applied to supply N at 90, 112. and 135 kg/ha, with an associated increase in P, K, and S. Main plots were split for open burning and two levels of mechanical residue removal. Two crops of red fescue and four seed crops of smooth bromegrass and crested wheatgrass were evaluated. Average seed yields (kg/ha) for burning compared with mechanical straw removal were 636 vs. 495 for red rescue, 1,122 vs. 848 for smooth bromegrass, and 872 vs. 790 for crested wheatgrass. Straw and stubble removal, compared with straw removal alone, increased seed yield of red rescue and smooth bromegrass, but decreased seed yield of crested wheatgrass. Interactions of fertilizer rates and residue management were not significant. Increasing the fertilizer rate did not compensate for the reduction in seed yield associated with mechanical removal of residue. Seed yields of smooth bromegrass and crested wheatgrass were increased by high fertilizer rates as the age of stand increased. The increase in seed production resulting from burning residue apparently was associated with control of downy bromegrass (Bromus tectorum L.) and increased vigor of autumn regrowth. Diseases and insects were of little consequence and probably had little influence on seed yield in these experiments.

Synopsis Burning of the straw and stubble after harvest was beneficial in maintaining high seed yields of intermediate wheatgrass. Mechanical removal of every other foot of vegetation in the row produced seed yields equal to burning. The effects of burning and mechanical thinning appeared to be additive. Increasing the rate of nitrogen was not effective in maintaining seed production as the stands became older.

The objectives of this paper are to discuss pertinent literature and to present some recent research concerning induction of the vegetative primordia and initiation of floral development in perennial cool‐season grasses. The amount of exposure to short photoperiod and cool temperatures under field conditions necessary for induction of three forage grasses and four cultivars of Kentucky bluegrass (Poa pratensis L.) was studied. Plants were moved from the field at 15‐day intervals from September 15 to March 15 and grown under long photoperiod and warm temperatures for the production of inflorescences.The number of inflorescences produced indicated that a high level of induction for smooth bromegrass [Bromus inermis (Leyss.)], crested wheatgrass [Agropyro desertorum (Fisch. ex. Link) Schult.], and orchardgrass (Dactylis glomerata L.) had been reached by October 15, November 1, and November 15, respectively. The four Kentucky bluegrass cultivars showed a significant linear response to exposure. Inflorescence production increased as the exposure time increased. Seed production for Kentucky bluegrass cultivars followed essentially the same pattern as inflorescence production in response to exposure. The time required for inflorescence emergence for all cultivars and species had a negative association with the length of exposure to inductive conditions. If the rate of inflorescence emergence was used as the index, induction intensity was increasing up to March 15.Observations of dissected tillers at weekly intervals indicated the initiation of floral development for smooth bromegrass by February 12, and for orchardgrass and crested wheatgrass by February 19. The apices of the Kentucky bluegrass cultivars show a transition to floral primordia by January 22 for Delta and by February 5, 12, and 26 for Newport, Cougar, and Merion, respectively. Transition of vegetative apices to floral development occurred under conditions of cold temperature and short photoperiod for all species and cultivars.

A study was conducted to determine the influence of cultivation, gapping of the initial stand, and in situ burning of the postharvest residue on the seed yields of ‘Pennlate’ orchardgrass (Dactylis glomerata L.) and ‘Newport’ Kentucky bluegrass (Poa pratensis L.). The two grasses were grown in separate but adjacent blocks. The experimental design for each species was a split‐plot with cultivation treatments as the main plots. One cultivation with a rotary hoe (minimum cultivation) in April of each year was the best method under conditions of these experiments. Additional cultivation with sweep‐shovels (conventional cultivation) reduced the seed yields of Kentucky bluegrass and did not influence the seed yields of orchardgrass. Kentucky bluegrass seed yields were reduced more by conventional cultivation in April than by similar cultivation in September. Conventional cultivation leaving a 30‐cm row width reduced seed yields more than leaving a 46‐cm row width. Gapping of the rows in the seedling year reduced the seed yields of both orchardgrass and Kentucky bluegrass in the first crop but had little effect on subsequent crops. Mechanical removal of postharvest residue was as effective as burning in orchardgrass seed production. Burning compared with mechanical removal of the postharvest residue produced lower seed yields of Kentucky bluegrass in the second and third crops, but higher yields in the fourth and fifth crops.