The pecularities of the behavior of Nymphaea candida Presl. flowers on lake Moldino (Tverskaya province).

Volkova P.A., Sonina S.I., Shipunov A.B.

[Russian variant]

The goal of our work was to study the particularities of the flower behavior of Nymphaea candida L. To reach this goal we marked these problems:

1)To study the dynamics of the behavior of Nymphaea candida flowers.

2)To find the factors which cause the rhythmic behavior of the flowers and intensity of the bloom of Nymphaea candida

3)To compare the rhythmic behavior of this species in different years.

4)To compare published material on biological rhythms of different plant species with our material on the behavior of Nymphaea candida flowers.

Observations were made for three seasons during the period from the 23rd to the 28th of June, 1998, from the 20th to the 29th of June, 1999, and from the 20th to the 29th of June, 2000 in the Udomelskii region, Tverskaya province. We studied populations of Nymphaea candida on lake Moldino, near the village Polukarpovo (57o 40', 35 o 10' e.lg.). In the period between 1998 and 2000 observations were made from 3 am till 11 pm, from 4 to 14 times. In overall 142 observations were made. During each observation the degree of the opening of the flower and the degree of it's immersion in the water was measured. Also once a day the step of its growth was marked. Apart from that, we registered the time of day, water temperature, air humidity, atmospheric pressure and the degree of cloudiness right on the spot of the observations. In a camp we measured the active and full sun radiation. All the results acquired from these observations were processed by the STATISTICA for Windows program package.

The analysis of the results made it possible to make the following conclusions:

1)The behavior of Nymphaea flowers is determined by their step of growth

2)Factors that change during the whole day regulate the amplitude of the opening of the flower and it's immersion.

3)The length of the Nymphaea `day' depends on the cloudiness and atmospheric pressure.

4)The intensity of bloom of the Nymphaea depends on the temperature of the air and the water.

5)Our materials on the particularities of the Nymphaea flower behavior do not disagree with other published material on biological rhythms of plants and they also extend the published data on the rhythmic of this species.

The degree of the Nymphaea flower immersion is determined by the length of the flower stalk of the plant. The change of the condition of the calyx and/or the petals will result with the change of the degree of the flowers opening. It is known, that the volume of the cells is proportionate to their turgor. Osmotic regulation in cells, which contain chlorophyll, is a result of three metabolic processes: ion transport (K+ and escorting anions), the forming of sugars during photosynthesis and starch degradation during which saccharose forms (Tallman, Zeiger, 1988). So, from the factors which affect the cells and, consequently, the flowers behaviour, the main factor is the intensity of metabolic processes in cell, for example, the intensity of photosynthesis. According to our data, the dynamics of changing of the flower stalk length is determined by the stage of flower development and the degree of this changing on the blooming stage during the day is regulated by the mean of the sun radiation and some other natural factors. This hypothesis is confirmed by the works by Winfri (1990) and Wilkins (1964).

The speed of changing of the flower stalk length is caused by the atmospheric pressure. It can be explained in the following way: then higher is the atmospheric pressure, then slower changes turgor, size of each cell, condition of the whole flower and flower stalk and, consequently, the degree of flowers immersion and opening, then longer is the `day' of Nymphaea. By this fact is the hypothesis of Bunning (1931) and the conclusions of Brown's experiments (Winfri, 1990) confirmed.

Nonlinear dependence of opening degree of flowers on their immersion degree during the blooming reliably prevents the pollen becoming wet. When the blooming ends and the pollination has taken place, this dynamics disappears and water freely penetrate into the flower. Besides, closing of the flowers at night during the blooming lets retain the insects inside the flower to make the pollination more probable.

In different years of our investigations the flowers behaviour had common tendency, but was different in the details because of different weather conditions.

The length of the blooming period depends on the speed of anthers ripening. In the base of this process may lie biochemical reactions, the speed of which is proportionate to the temperature (Shwemmle, 1964; Bunning, 1931) and may also depend on some other natural factors.