Biology and ecology of blossoming Bunias orientalis L. in culture in the European Northeast

The present work aims at flowering biology and ecology of Bunias orientalis L. in culture in the North. It belongs to the Brassicaceae Burnett (Cruciferae Juss. nom. altern.) family and is a polyzonal European species. On the territory of the Komi Republic the plant occurs as an adventitious, one-two-year herbaceous plant growing in weedy places in the taiga, more rare in the tundra zone. The studies were conducted at the experimental field area of the Botanical Garden of the Institute of Biology, Komi Sci. Centre, Ural Branch, RAS in 2007-2011. The study materials were uneven-aged B. orientalis plants. They maintained natural phenological rhythms. B. orientalis refer to long-term vegetating, early-midsummer flowering plants. The period from regrowth to fruiting is 95-119 days depending on weather conditions and plant age. In culture, the plants start flowering on the 36-48th day after spring regrowth, i.e. in the second-third decade of June. The flowering period is long and makes 15-36 days. The beginning of seeds maturation is in the second decade, mass maturation - during the third decade of August. Species of B. orientalis annually form mature seeds, which after fall and natural stratification in spring next year give abundant selfseeding. B. orientalis is a cross-pollinated entomophilous plant. Cross pollination is provided by dichogamy (protandry). Flower development goes by two stages: stamenate and pistillate. In favorable conditions the maturation of anthers occurs on the second day of flowering and stigmas - on the third day. In the middle-taiga subzone of the Komi Republic, B. orientalis forms a closed triple cluster from racemes. A floral unit is an open leafless raceme. Buds in the inflorescence get open in the acropetal order (upwards). The flowering period covers the most favorable part of vegetation period, i.e. end of June-July. The flowering period of agropopulation varies from 15 to 25 days, one flower lives from 3 to 7 days. From 24 to 411 flowers on one plant get open daily. 187±58 and 133±48 flowers per plant individual got open daily in 2008 and 2010, correspondingly. The daily rate of flower opening is represented by a one-peak curve and is relatively stable with a peak at 7-8 a.m. Flowers of B. orientalis get open at temperatures of 16-22 °C and relative air humidity of 65-69% within an hour.