Helena Kubicka-Matusiewicz, Marta Matusiewicz, Teresa Skrajna**

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1 OCHRONA ŚRODOWISKA I ZASOBÓW NATURALNYCH ENVIRONMENTAL PROTECTION AND NATURAL RESOURCES 213 VOL. 24, NO 2(56): DOI /oszn Helena Kubicka-Matusiewicz*, Marta Matusiewicz*, Teresa Skrajna** Morphological diversity of Polygonum lapathifolium L. subsp. lapathifolium in the agrocenoses of the Wigry National Park and its buffer zone Zróżnicowanie morfologiczne Polygonum lapathifolium L. subsp. lapathifolium w agrocenozach Wigierskiego Parku Narodowego i jego otuliny *Prof. dr hab. inż. Helena Kubicka-Matusiewicz, mgr Marta Matusiewicz The Polytechnic Institute, Higher Vocational School In Suwalki im. prof. Edwarda F. Szczepanika in Suwalki, T. Noniewicza 1St, 16-4 Suwalki; phone: , helenakubicka@wp.pl, martam13@op.pl **Dr inż. Teresa Skrajna Department of Agricultural Ecology, The University of Natural Sciences and Humanities in Siedlce, Konarskiego 2St, 8-11 Siedlce; phone: ; tskrajna@op.pl Keywords: cultivated land, Polygonum lapathifolium L. subsp. lapathifolium, segetal weeds Słowa kluczowe: Polygonum lapathifolium L. subsp. lapathifolium, chwasty segetalne, uprawy rolnicze Abstract In the years 29 and 21, studies were carried out on Polygonum lapathifolium L. subsp. lapathifolium population established in the cultivated fields of the Wigry National Park and its buffer zone. Every year, 3 plants of the Polygonum lapathifolium L. subsp. lapathifolium were picked and collected from each of the three habitats: potato fields, winter and spring cereals. The following traits were examined: plant height, stem length to the first branching, number of internodes and their length, number of first-order branches and their length, number of leaves, number of spikelet-like inflorescences (spikelets) and their average length, the top inflorescence (spikelet) length, seed number per plant and 1-seed weight. The analysis of the obtained results indicated large morphological variability of plants, which depended on the type of cultivated land. The most favourable conditions for weed growth and development occurred in potato fields, where Polygonum lapathifolium L. subsp. lapathifolium plants were the highest, most branched and productive. The opposite result was noticed in winter cereals, where Polygonum lapathifolium L. subsp. lapathifolium managed to produce the least seeds. Comparisons of the results of morphological measurements for Polygonum lapathifolium L. subsp. lapathifolium taken in the same sites during two growing seasons demonstrated relatively small variation of the analysed traits. Streszczenie W latach badano populacje Polygonum lapathifolium L. subsp. lapathifolium zachwaszczające uprawy rolnicze Wigierskiego Parku Narodowego i jego otuliny. Każdego roku zebrano po 3 roślin analizowanego taksonu z trzech siedlisk: upraw ziemniaka, zbóż ozimych oraz jarych. Wykonano pomiary biometryczne następujących cech: wysokość rośliny, długość łodygi do I odgałęzienia, liczba międzywęźli i ich długość, liczba odgałęzień I rzędu i ich długość, liczba liści, liczba kłosokształtnych kwiatostanów (kłosków) i ich średnia długość, długość kwiatostanu (kłoska) szczytowego, liczba nasion z jednej rośliny i masa 1 nasion. Analiza wyników wykazała dużą zmienność morfologiczną wśród roślin Polygonum lapathifolium L. subsp. lapathifolium w zależności od uprawy, w której rosły. Najkorzystniejsze warunki do wzrostu i rozwoju tego podgatunku występowały w uprawach ziemniaka, gdzie wśród pobranych roślin stwierdzono największe rozmiary, największą ilość rozgałęzień i największą plenność. Natomiast najbardziej konkurencyjnym wobec badanego chwastu okazały się zboża ozime, w których to uprawach rośliny Polygonum lapathifolium L. subsp. lapathifolium wytwarzały najmniej nasion. Porównanie uzyskanych wyników pomiarów cech morfologicznych Polygonum lapathifolium L. subsp. lapathifolium z tych samych stanowisk z dwóch badanych sezonów wegetacyjnych wykazało niewielkie zróżnicowanie analizowanych cech. IOŚ-PIB 1. INTRODUCTION Individual variability in weed populations is an effect of different habitat conditions in cultivated fields. These conditions are determined by soil (moisture content, nutrient status), light and, to a large extent, the crop plant and agricultural practices. Crop plants are accompanied by weeds having characteristics such as a short life cycle and abundant seed production, enabling them to survive and develop under conditions of increased human pressure. Most weeds produce a huge number of seeds. These seeds mature and spread into the soil before/at the time of crop plant harvest. The seeds added to the soil seedbank germinate in the same or next growing seasons [Podstawka-Chmielewska et al. 2, Jędruszczak 2, Jędruszczak et al. 24, Kwiecińska 24, Kwiecińska-Poppe 26]. Polygonum lapathifolium L. subsp. lapathifolium is a segetal weed found in communities establishing in various crop plants. The subspecies is very popular in root crops, specifically in potato, where it is a noxious weed which is difficult to control. Due to its high nutritional requirements, the weed finds the best conditions to grow and develop in root crops. Under these conditions, Polygonum lapathifolium L. subsp. lapathifolium reaches fairly large size and produces a large number of seeds. This plant is also frequently observed in cereal crops [Tymrakiewicz 1962, Szafer et al. 1988]. Korniak [1992] conducted long-term studies and found that the weed tends to be more popular in north-eastern Poland. This plant is characterised by its stems slightly swollen at the joints, called nodes, and white flowers collected in quite long drooping 35

2 Helena Kubicka-Matusiewicz, Marta Matusiewicz, Teresa Skrajna inflorescences. These features are variable and difficult to identify, especially when plants grow in cereal crops. In earlier times, the weed used to be classified as a separate species [Mowszowicz 1979, Szafer et al. 1988], but now it has been reclassified as a subspecies of Polygonum lapathifolium L. pale persicaria [Mirek et al. 22, Rutkowski 26]. The leaves of some plants have got a dark blotch in the middle of the blade, or the underside of one or a few leaves could be slightly pubescent [Rutkowski 26]. There are morphological differences between plants of Polygonum lapathifolium L. subsp. lapathifolium depending on the plant community in which the species grows [Skrzyczyńska et al. 29]. The aim of this work was to analyse the morphological diversity of Polygonum lapathifolium L. subsp. lapathifolium populations establishing in potato fields as well as winter and spring cereals in the Wigry National Park and its buffer zone. 2. MATERIALS AND METHODS Plants of Polygonum lapathifolium L. subsp. lapathifolium were examined. They were collected in potato fields as well as in fields of winter and spring cereals, with similar habitat conditions, located in the Wigry National Park and its buffer zone in In the park, agricultural land covers 22 ha, which is approximately 15% of the whole park area. There are small farms, with an average area of 1 ha of cultivated land. Moreover, the severe climate and poor soils determined conducting of traditional extensive farming in this area, with small amounts of plant protection products and mineral fertilisers. In order to determine the intensity of occurrence of the subspecies, at each site, plants were sampled for analysis, and phytosociological relevé by the Braun-Blanquet method was taken [Pawłowski 1972]. Polygonum lapathifolium L. subsp. lapathifolium plants were the most frequently observed in potato fields. Simultaneous studies carried out in the Wigry National Park and its buffer zone revealed that weed infestation indicators for this subspecies were the highest in potato fields and is suggested to create a considerable risk to the crop plants [Skrajna et al. 211]. The subspecies was also frequent in spring cereals but with a lower land cover. This weed was rarely observed in winter cereals, but no specimens were collected in winter cereals in 29. Each year, thirty plants were randomly sampled from individual fields (total of 18 plants) and measured to obtain values describing their morphology. Measurements of plant height and stem length to the first branching were taken. Internodes and first-order branches were counted and the lengths of the latter were measured. Number of leaves and spikelet-like inflorescences were determined in addition to the average inflorescence length and top inflorescence length. Seed number per plant was calculated as the sum of seeds from all the spikelets of a plant. The 1-seed weight was also determined. The medium mean and coefficient of variation were calculated and differences between means were checked using Tukey s test. 3. RESULTS AND DISCUSSION On the basis of biometric measurements of Polygonum lapathifolium L. subsp. lapathifolium plants obtained from fields planted with different crops, it was shown that plants of this subspecies tend to be morphologically differentiated. Table 1 presents the average values of characteristics for both the study years as well as variability ranges for each habitat studied. The largest and most branched plants of Polygonum lapathifolium L. subsp. lapathifolium were found in potato crops, 68.4 cm high on average. The tallest plant reached 132. cm in height and had relatively numerous and thick side branches which were as much as 1. cm long. Weeds collected in cereals were significantly shorter (α =.5): on average, 47.5 and 43.6 cm tall in spring and winter cereals, respectively. Polygonum lapathifolium L. subsp. lapathifolium plants sampled in spring cereals were almost as tall as plants sampled in root crops, though they were not so branched. Polygonum lapathifolium L. subsp. lapathifolium populations were substantially different with respect to their branching characteristics. The first-order branch developed was quite high on the stem in all the populations. These branches were formed in the lowest part of the plant stem sampled from winter cereals at 14.5 cm of Table 1. Mean values, range of variability and variation coefficient () for the traits measured in Polygonum lapathifolium L. subsp. lapathifolium populations between 29 and 21. Cultivated land Traits plant height (cm) Potato fields Winter cereals Spring cereals 68.4* ( ) ( ) ( ) stem length to the first branching (cm) 16.3 (.5 74.) (1. 19.) * (.1 79.) number of first-order branches 7* (1 17) (1 2) (1 5) 63.5 length of first-order branches (cm) 24.6* ( ) ( ) (5. 24.) number of internodes 13* (8 2) (6 13) (7 16) 17.7 internode length (cm) 5.* ( ) ( ) ( ) number of leaves 64* (12 321) * (5 21) * (5 46) number of inflorescences 82* (6 395) * (1 11) * (1 31) inflorescence length (cm) 1.9* (1. 3.2) (.5 1.6) (.5 1.5) length of top inflorescence (cm) 3.5* (2. 5.4) * (.7 2.7) * (.7 4.4) seed number per plant 3591* ( ) * (11 191) * (8 937) the 1 seed weight (g) 2.58* ( ) *differences significant at α =

3 MORPHOLOGICAL DIVERSITY OF POLYGONUM LAPATHIFOLIUM L. SUBSP. LAPATHIFOLIUM IN THE AGROCENOSES OF THE WIGRY NATIONAL PARK AND ITS BUFFER ZONE height, on average, and the highest for plants found in spring cereals at 31. cm of height, on average, with the maximum height of 79. cm. Specimens collected from both winter and spring cereal fields, had a similar number of first-order branches and were of similar length 12.3 and 1.4 cm, respectively. Conditions in a cereal stand make it more difficult for weeds to produce long side branches. There were more than twice as long first-order branches in weeds sampled in potato fields. They were 24.6 cm long, on average, with the maximum length of 56. cm for the longest plants. Also, number of first-order side branches per plant was the greatest, and it averaged 7 with the maximum number of 17. The favourable habitat conditions of the potato fields encouraged the growth and development of weeds. Compared with other agricultural plants, cultivation of root crops creates conditions hospitable to most weeds. It is a result of an influence of many factors including: wide inter-row spacing, good light penetration, high soil moisture, nutrient availability in the soil due to an application of farmyard manure, slow growth of potato plants at initial stages of development, a long growing season and poor species competitiveness [Kwiecińska-Poppe 26, Różyło, Pałys 27]. Thus, weeds are able to tiller, branch, produce generative shoots and a lot of seeds. The development of segetal plants, and their fruits and seeds production are reduced in dense cereal stands [Podstawka-Chmielewska et al. 2, Kwiecińska 24, Matusiewicz et al. 21]. A very important characteristic of weeds is abundant seed production which enables them to persist in agrocenoses. Plants of Polygonum lapathifolium L. subsp. lapathifolium sampled in potato crops significantly differed in this respect compared to specimens sampled in cereals. They formed a lot of spikeletlike inflorescences (82 on average), with the maximum value of almost 4 inflorescences per plant and the inflorescences were much larger. The average length of the top inflorescence in this population was 3.5 cm, with the maximum length of 5.4 cm. What is more, the population discussed had the greatest potential of seed production. The average seed number per plant was 3591 and the most prolific plants produced over 1 seeds. In addition, seeds of the plants sampled from potato fields were the largest, the weight of these 1 seeds was 2.58 g. The least prolific plants were collected in winter cereals and their average inflorescence number and seed number per plant were 3 and 38, respectively. The results obtained for seed production in cereal populations differ from that reported by Kwiecińska-Poppe [26]. She observed that the weed potential of seed production in winter cereals is significantly greater than those in spring cereals. According to this author, rapid germination and growth of spring cereals give them more competitive advantage over segetal plants which are also shaded. In the study area, plants of Polygonum lapathifolium L. subsp. lapathifolium in spring cereals developed twice as many spikelets and produced significantly more seeds compared to plants growing in winter cereals. Similar results for this subspecies were reported by Skrzyczyńska et al. [29] who have also recorded the lowest seed numbers produced by plants establishing in winter cereals. Polygonum lapathifolium L. subsp. lapathifolium populations establishing in potato differed significantly with respect to most of the characteristics studied from populations observed in the remaining agricultural crops. However, no significant differences were found between populations establishing in winter and spring cereals, with the exception of statistically significant differences between leaves, spikelets and seed numbers. Comparisons of the results of morphological measurements for Polygonum lapathifolium L. subsp. lapathifolium taken in the same sites during two growing seasons demonstrated relatively small variation of the analysed features (figs. 1, 2, 3, 4). Plants sampled from potato fields in 29 were slightly smaller but they produced more leaves, spikelets and seeds, on average, compared with plants sampled in 21. Better conditions of development were observed for the species establishing in spring cereals in 29. As a result, plants were significantly higher, produced more leaves, had longer inflorescences and produced more seeds. The effect of weather conditions is suggested to be the main determinant of this phenomenon. plant height (cm) length of first-order branches (cm) potato fields winter cereals springg cereals Fig. 1. The average plant height and length of first-order branches in the populations of Polygonum lapathifolium L. subsp. lapathifolium in the study sites in

4 Helena Kubicka-Matusiewicz, Marta Matusiewicz, Teresa Skrajna Fig. 2. The average number of leaves and inflorescences in the populations of Polygonum lapathifolium L. subsp. lapathifolium in the study sites in length of top inflorescence (cm) 4,5 4 3,5 3 2,5 2 1,5 1, potato fields winter cereals spring cereals Fig. 3. The average length of top inflorescence in populations of Polygonum lapathifolium L. subsp. lapathifolium in the study sites in CONCLUSIONS 1. There was individual variability in morphology of Polygonum lapathifolium L. subsp. lapathifolium depending on habitat conditions: the best conditions of growth and development were created in potato fields. 2. Statistically significant differences were found between values of the analysed features of plants sampled from potato and cereal fields. 3. Weeds collected from winter cereals were the smallest, produced the least seeds and were in general infrequent in these habitats, so it is suggested, that conditions for the development of Polygonum lapathifolium L. subsp. lapathifolium were least favourable. 38

5 MORPHOLOGICAL DIVERSITY OF POLYGONUM LAPATHIFOLIUM L. SUBSP. LAPATHIFOLIUM IN THE AGROCENOSES OF THE WIGRY NATIONAL PARK AND ITS BUFFER ZONE seed number per plant potato fields winter cereals spring cereals Fig. 4. The average seed number per plant in populations of Polygonum lapathifolium L. subsp. lapathifolium in the study sites in REFERENCES JĘDRUSZCZAK M. 2. Reprodukcja generatywna chwastów na ścierniskach po życie ozimym. Annales UMCS, sec. E Agricultura LV (8): JĘDRUSZCZAK M., BOJARCZYK M., SMOLARZ H., DĄBEK- -GAD M. 24. Konkurencyjne zdolności pszenicy ozimej wobec chwastów w warunkach różnych sposobów odchwaszczania behawior zbiorowiska chwastów. Annales UMCS, sec. E Agricultura LIX (2): KORNIAK T Ekspansywne gatunki chwastów segetalnych w północno-wschodniej części Polski. Zeszyty Naukowe Akademii Rolniczej im. Hugo Kołłątaja w Krakowie 261: KWIECIŃSKA E. 24. Plenność niektórych gatunków chwastów segetalnychna glebie lekkiej. Annales UMCS, sec. E Agricultura LIX (3): KWIECIŃSKA-POPPE E. 26. Plenność wybranych gatunków chwastów segetalnych na ciężkiej rędzinie czarnoziemnej. Acta Agrophysica 8(2): MATUSIEWICZ M., KUBICKA H., SKRAJNA T., WAŁEJKO A. 21. Fenotypowe zróżnicowanie gatunków Polygonum na terenie Suwalszczyzny. Ochrona Środowiska i Zasobów Naturalnych 44: MIREK Z., PIĘKOŚ-MIREK H., ZAJĄC A., ZAJĄC M. 22. Krytyczna lista roślin naczyniowych Polski. Instytut Botaniki im. W. Szafera Polska Akademia Nauk Kraków. MOWSZOWICZ J Pospolite rośliny naczyniowe Polski. Państwowe Wydawnictwo Naukowe Warszawa. PAWŁOWSKI B Skład i budowa zbiorowisk roślinnych oraz metody ich badania. (w:) Szata roślinna Polski [The composition and constitution of plant communities and methods of their examination. (in:) Plant cover of Poland] 1. Wyd. Nauk. PWN, Warszawa: (published in Polish). PODSTAWKA-CHMIELEWSKA E., KWIATKOWSKA J., KOSIOR M. 2. Plenność niektórych gatunków chwastów segetalnych w łanie różnych roślin uprawnych na glebie lekkiej i ciężkiej. Annales UMCS, sec. E Agricultura LV (4): RÓŻYŁO K., PAŁYS E. 27. Wpływ systemów nawożenia na zachwaszczenie ziemniaka jadalnego uprawianego na glebie lekkiej i ciężkiej. Annales UMCS, sec. E Agricultura LXII (1): RUTKOWSKI L. 26. Klucz do oznaczania roślin naczyniowych Polski niżowej. Wydawnictwo Naukowe PWN, Warszawa: 111. SKRAJNA T., KUBICKA H., MATUSIEWICZ M Udział wybranych gatunków Polygonum w zachwaszczeniu upraw na terenie Wigierskiego Parku Narodowego. Ochrona Środowiska i Zasobów Naturalnych 49: SKRZYCZYŃSKA J., ŁUGOWSKA M., SKRAJNA T. 29. Wybrane cechy Polygonum lapathifolium subsp. lapathifolium w zależności od gatunku rośliny uprawnej. Pamiętnik Puławski 15: SZAFER W., KULCZYŃSKI S., PAWŁOWSKI B Rośliny polskie. PWN, Warszawa. TYMRAKIEWICZ W Atlas chwastów. Państwowe Wydawnictwo Rolnicze i Leśne. Warszawa. 39