Crop production must continuously be adjusted according to economic return and fluctuating prices on inputs versus harvested plant products and calls for continuous revision of the crop rotation and flexible management systems. This study describes grass seed production of three different types, respectively, of perennial ryegrass (Lolium perenne L.) and red fescue (Festuca rubra L.) and their optimum number of growing seasons in terms of yield, selected yield components and economic gain. Three harvest years gave the maximum yield in the red fescue type with long stolons (cv. Pernille) and the highest number of fertile tillers in all three red fescue cultivars. Four harvest years gave the maximum yield for types with short stolons (cv. Suzette) and without stolons (cv. Tamara). The fifth year significantly reduced the yield compared to the highest obtained yield within each cultivar. The diploid amenity cv. Allegro and forage type cv. Borvi of perennial ryegrass can be harvested in five consecutive years without a significant yield reduction. The tetraploid type cv. Tivoli had the highest thousand seed weight and a significant yield decrease from the first to the second year of seed harvest and a continuous decline in seed yield is observed from the first to the fifth harvest year in this cultivar. Yet, when the economic incentive was calculated it was found that optimum harvest years cannot be determined by yield considerations alone. A combination of high grass seed price and low cereal price shows that red fescue can be grown up to four years and perennial ryegrass up to five years with high economic returns.
Acta Agriculturae Scandinavica. Section B. Soil and Plant Science, 2013, Vol 63, Issue 1, p. 1-10