THE INFLUENCE OF ORIGIN OF HELICHRYSUM ARENARIUM ( L . ) MOENCH INDIVIDUALS ON THEIR INFLORESCENCE YIELD AND GERMINATION ABILITY

Helichrysum arenarium (L.) Moench is a perennial of the Asteraceae family. The species is partially protected in Poland. Its infl orescence is a source of valuable herbal material. The amount of fresh and dry mass of infl orescences collected from plants growing in natural stands and those obtained from experimental plantations was analyzed. The plants growing in the plantation were obtained from in vitro cultures. Germination ability of achenes was also tested. The number of fl owering shoots per plant, the number of plants per area unit as well as the fresh and dry mass of infl orescences depended signifi cantly on the soil conditions and precipitation. Cultivation of H. arenarium gives a signifi cantly higher fresh and dry mass of infl orescences per plant and a higher yield per area unit. The yield of herbal material from a plantation can vastly exceed that from the natural stands. Stratifi cation of achenes prior to their germination resulted in an increase in the number of seedlings by 9.6%. Germination ability markedly decreased with time. Therefore, it is likely that the achenes form a transient seed bank. Achenes from plants obtained by in vitro method exhibited the lowest germination ability, so they should not be used as seed material.


INTRODUCTION
. H. arenarium grows in sunny places on sandy soils, in dry forests and thickets, along waysides and in abandoned fi elds (R u t k o w s k i , 1998).
Within the past few years, in many regions of Poland the cultivation of barren, sandy soils was stopped.
As a result of vegetation succession, H. arenarium has started to grow in these areas.However, the advancing succession changes the fl oristic composition of these phytocoenoses and leads to retreat of the species (S aw i l s k a , 2006; 2007).In the years 1975-1977 P ac h o l a k and Z a ł ę c k i (1979) made an attempt at growing H. arenarium in plantations, but with no success, as many plants died in the second year of cultivation (B u c h w a l d , 1992).Therefore, a new project of growing H. arenarium was started to provide an effective method for establishing plantations.The in vitro procedures proved to be a successful technique for obtaining H. arenarium seedlings (S a w i l s k a and F i g a s , 2006; S a w i l s k a and J e n d r z e j c z a k , 2007).
The goal of this work was to determine the differences in infl orescence yield obtained form natural stands and plantations of the species.A detailed analysis of fresh and dry mass of infl orescences from natural sample plots and plantations of different age was performed.Germination ability of achenes of different age and origin was also examined.2006; 2007).Infl orescence yield per 1 m 2 was estimated from the collected data for populations I and II.Plants from the experimental fi eld in Mochełek were subject to thorough analysis: their fl owering shoots were counted, the fresh and dry mass of infl orescences per individual as well as the infl orescence yield per 1 m 2 were measured.

Infl
The germination ability of achenes and the changes in the percentage of germinated seeds as a function of seed age and stratifi cation were examined (E l l i s et H. arenarium from both populations grew on natural soils classifi ed as clayey sands, while in Mochełek it was grown on sandy clayey (see S a w i l s k a and J e n d r z e j c z a k , 2007 for detailed characteristics of the substrata).Because of different geographical locations, the plants from populations analyzed grew under various weather conditions.Mean month temperature was similar for both locations, but precipitation differed signifi cantly (Tab.1).
Statistical analysis was performed using EXCEL and STATISTICA PL software.Regression analysis was applied to determine the infl uence of habitat factors on the yield.Basic regression equations (Ł o m n i c k i , 1995) were computed to assess the associations between variables.

RESULTS
The number of fl owering shoots, mass of the infl orescences per plant, the plant density and the yield varied with the geographical location and the origin of plants (natural stands or plantation); see Tab. 2. All features analyzed were highly correlated with weather conditions within the study period (±0.54 ≤ r ≤ ±0.93).
Plants from natural stands produced less generative shoots compared to those grown in plantation.However, in the second year an increase in the number of generative shoots was reported for all four populations.The highest value of this feature was observed in 2006 for plants from the plantation in Mochełek.In turn, the highest plant density was observed in the natural stands (Tab.2).The number of plants m -2 increased in the sub-   In the natural stands, the highest fresh infl orescence mass was observed for the population I in 2006 (an increase by 78.6% compared to the previous year).Fresh infl orescence mass for the population II was si-milar in both study years.Dry infl orescence mass was higher in 2006 compared to the previous year by 81.8% for the population I and 25.0% for the population II (Tab.2).Fresh infl orescence mass of the plants from Mochełek was lower in 2006 by 38.2% for individuals grown at spacing 40 30 cm and by 40.7% for individuals grown at spacing 40 15 cm, compared to the previous year.Dry infl orescence mass for spacing 40 30 was similar in both study years, while that for the spacing 40 15 increased by 18.7% in 2006 (Tab.2).
Distinct differences between the natural populations and plants from Mochełek were recorded for fresh and dry infl orescence mass (Tab.2).Mean values of these features for the plants from Mochełek in 2005 resembled those for 2006 and were higher by 98.7% on average than the values determined for the natural populations.
The yield of fresh and dry infl orescence mass per 1 m 2 recorded for the natural populations changed over time.In 2006 the yield compared to that of the previous year increased in both populations.The increase was 89.8% of fresh mass and 91.4% of dry mass for the population I, and 15.5% and 37.7%, respectively, for the population II (Tab.2).The differences (fresh vs. dry mass) recorded for the population from Mochełek in the years 2005-2006 were less distinct.In 2006 the fresh mass of infl orescences from plants grown at spacing 40x30 dropped by 39.4%, while the amount of dry mass remained relatively unchanged.For the 40 15-spacing, the fresh infl orescence mass dropped by 46.9%, and the dry mass increased by 10.7% in the second year.
The results of the experiment conducted in 2006 showed that stratifi cation of achenes prior to their germination resulted in an increase in the number of seedlings by 9.6%.The highest germination ability was exhibited by the achenes of plants transferred from the natural stands to the plantation (Tab.3).A high germination percentage was recorded also for achenes from the population I.However, germination ability markedly decreased with time.

DISCUSSION
Reproduction potential of a plant population depends on its age, the number of propagules produced, and longevity of individuals that build the population (C z a r n e c k a , 2007).The number of infl orescences and the number of fl owers per infl orescence is a function of a general habit of the plant (C z a r n e c k a , 1995).The fl owering pattern, in turn, is modifi ed by small-scale habitat factors such as soil humidity and fertility, and light intensity (C z a r n e c k a , 2006).
In the case of Helichrysum arenarium, the number and mass of infl orescences depend on the number of shoots per plant (Tab.2).Growth and development of the individuals are also modifi ed by habitat factors.The studies conducted show that the amount of precipitation signifi cantly affects the number of shoots per plant and the plant population density (S a w i l s k a , 2007).The density of the population II was much higher than that of the other population.This can be ascribed to the different age and phytosociological characteristics of the two H. arenarium communities (S a w i l s k a , 2007).The differences in precipitation appear to be of some infl uence too (Tab.1, 2).
The studies showed distinct differences in infl orescence mass between the natural populations and plants from the plantation (Tab.2).Fresh and dry mass of infl orescences from plants grown in the plantation were on average higher as much as 98.7% than those for plants from natural stands.However, the infl orescence mass per plant was higher in 2006 for both populations, while in the plantation there was a drop in the mass by 39.2%.The fresh infl orescence yield was therefore reduced by 43.6%.This decrease could be caused by lower precipitation in May and June compared to that in the year 2005 and by plant aging (Tab. 1, 2).H. arenarium was grown under optimum conditions for its development, therefore the dry infl orescence yield was on average 25.7 fold higher than that obtained from natural stands.
40 15 spacing turned out to be better for growing H. arenarium, in spite of a higher mortality observed for that spacing (13.3% of the plants died by the fi rst growing season, and 10.3% after the second year) and resulting weed emergence.
Germination experiments were carried out under optimal light, temperature and soil moisture conditions (E l l i s et al. 1985).Yet there is another group of factors infl uencing seed germination, e.g. the number of diaspores per plant as well as their somatic and functional differentiation (C z a r n e c k a , 1997).Almost all achenes collected from population I in 2005 and from plants transferred in 2004 from natural stands in Bory Tucholskie to Mochełek germinated (Tab.3).Achenes from the plants obtained by in vitro method exhibited the lowest germination ability, so they should not be used as seed material.
The studies on germination of achenes of Calendula and Achillea (F o r m a n o w i c z o w a et al. 1998) suggested that germination ability of H. arenarium achenes would also be retained for 2-3 years.It turned out, however, that the seeds were rapidly losing their viability (Tab.3).Therefore, it is likely that the achenes form a transient seed bank.They are, however, easily dispersed by wind and capable of fast germination without dormancy that facilitates invasion of new areas (cf.Ven a b l e and L e v i n , 1983).
Summing up: 1.The number of fl owering shoots per plant, the number of plants per area unit as well as the dry and fresh mass of infl orescences depended signifi cantly on the soil conditions and precipitation.Spring showers boosted growth of H. arenarium and development of more and larger infl orescences.
2. Cultivation of H. arenarium on sandy soils can give a signifi cantly higher (25.7-fold on average) dry mass of infl orescences (herbal material) than that from natural stands.

Wpływ pochodzenia roślin
Helichrysum arenarium (L.) Moench is a perennial of the Asteraceae family.The species is partially protected in Poland.Its infl orescence (Infl orescentia Helichrysi = Flos Stoechados citrini) collected at the beginning of the blooming season is a source of valuable herbal material (G a w r o n -G z e l l a et al. 2003; O ż a r o w s k i , orescences for the studies were collected in the years 2005 and 2006 from generative shoots of plants growing in natural stands and cultivated on experimental fi elds in University of Technology and Life Sciences Experimental Station in Mochełek.Natural phytocoenoses under study were located in the outskirts of Bydgoszcz (Fordon -population I) and in the Łosiny village within the Bory Tucholskie forest complex (population II).The phytocoenoses represented different stages of secondary succession (S a w i l s k a , 2006; 2007).Experimental plots with H. arenarium seedlings obtained by in vitro method were established in spring 2004.Micropropagules adapted to greenhouse conditions were planted in rows 40 cm apart with 15 or 30 cm between the seedlings.The seed material used in this work was collected from plants of the two wild populations in the years 2003-2005 and from experimental fi elds in 2005.Achenes from Mochełek were collected from the following three groups of plants: -specimens transferred in 2004 from natural stands, -individuals obtained by in vitro method and planted in 2004, -plants obtained from seeds collected in Bory Tucholskie sown in 2005.The density of H. arenarium shoots was measured and samples of 30 individuals were collected in the blooming peak in July in the years 2005-2006.The number of fl owering shoots per plant, the number of infl orescences per shoot and their fresh and dry mass were determined (F a l i ń s k a , 2002; S a w i l s k a , al. 1985; F o r m a n o w i c z o w a et al. 1998).The following temperatures were applied for two weeks: 30 o C 8 h during day time and 20 o C 16 h during night time.
sequent year.The highest plant density was observed for the population II: 25.0 plants m -2 in 2005 and 30.1 plants m -2 in 2006.In Mochełek, where the individuals were grown at 40 30 cm spacing, the plant density remained more or less constant (only 2 plants out of 90 died).However, in the years 2004-2006 on the fi eld with 40 15 cm spacing almost one fourth of individuals withered.
Air temperature and precipitation in the years 2005 and 2006 (data from Mochełek and Chojnice meteorological stations).

Table 2
Features describing the fi eld of Helichrysum arenarium.