Effect of the cutting date on blooming and fruit-bearing of Ostericum palustre Beesser

In fresh moist meadows, double-cut, located in the Bydgoszcz Canal Valley, you can find Ostericum palustre, a species of priority importance, which requires protection in the form of designation of Natura 2000 sites. The aim of the present research was to define the effect of the cutting date on blooming and fruit-bearing of O. palustre in meadows covered by the PO1b agro-environmental programme. Phenological observations included three populations of O. palustre. The first one occurs in a traditionally used meadow, not covered by the agro-environmental programme (2) where the date of the first cut falls in mid June. The second one is located in a meadow covered by the agro-environmental programme (1) where the first cutting date is possible from July 1, and the third population located in a natural meadow is not agriculturally used (0). The present research showed that individuals of O. palustre in the traditionally used meadows (2), prior to the first cut, reach the leaf rosette phase, while individuals which occur in the meadow covered by the agro-environmental programme (1), prior to the first cut, reach the generative tiller phase. Full bloom of O. palustre in the traditionally used meadows occurs after July 20, while individuals of O. palustre in the agro-environmental programme reach that phase only at the beginning of August. At the same time, about August 6, the first inflorescence in 70% of individuals in the agriculturally unused meadow (0) has ripe fruit, and in mid August all fruits are ripe. In mid August 70% of individuals in the meadow used for traditional cutting have ripe fruits of the first inflorescence, and right before the second cut, on August 27, almost 90% of fruits were ripe. Most O. palustre individuals in the meadows covered by the agro-environmental programme do not finish blooming of the first inflorescence before mid August. By the end of August, about 60% of individuals reach the phase of young fruits. The first ripe fruits occur as late as September 12. About September 20 most fruits are ripe. To sum up, delayed PO1b agro-environmental programme meadow cutting, after July 1, does not facilitate the production of ripe fruit in O. palustre individuals.