Browsing by Subject "tyvisipuli"

Timothy (Phleum pretense, L.) is the most widely grown grass species in Nordic countries and is well adapted for boreal climate because of its excellent winter hardiness. Adequate cold hardening in autumn is required for successful overwintering. During cold hardening large quantities of soluble sugars and low molecular nitrogenous compounds accumulate in stem bases. Soluble sugars are used during winter for energy and they also act as cryoprotectants. Nitrogenous compounds are involved in protein synthesis during cold acclimation as well as act as N-storage during regrowth. Among grasses, the role of vegetative storage proteins (VSP) as a long-term N-storage is under lesser research. The aim of this study was to investigate how N-fertilization effect growth, the amount of soluble sugars (WSC) and soluble proteins in timothy stem bases during cold hardening in late autumn and before regrowth in spring. Field experiments were conducted in LUKE research stations at Maaninka and Ruukki. Two timothy varieties, Nuutti and Grindstad with four different N-levels, ranging from 150- to 450 kg N/ha, were used. The autumn growth didn’t differ significantly between varieties, however, Nuutti accumulated more soluble sugars mainly due to its larger stem bases. The amount of soluble proteins and total nitrogen were significantly higher in Nuutti. N-fertilizing increased winter damage when more than 250 kg N/ha was applied. The amount of soluble sugars decreased approx. 50 % during winter whereas the amounts of total nitrogen and soluble proteins increased. Nitrogen didn’t have a negative effect on the amount of living stem bases in spring. SDS-PAGE-results showed a few potential polypeptide chains that might be related to VSP- or cold stress protein synthesis in autumn. Nitrogen had a positive effect on the amount of soluble sugars up to application of 350 kg N/ha. Nitrogen had a positive effect on the amount of total nitrogen and soluble proteins especially in spring. Those results might indicate better spring growth. The number of dead stem bases was lower on higher N-levels in spring and the number of living stem bases in spring was insignificant of N-level or variety. The role of VSP as a N-storage could not be clarified in this experiment.