Allelopathic effect of Polygonum lapathifolium L. on germination and initial growth of soybean
Baličević Renata1,Ravlić Marija1,Gorički Damir1,2, Ravlić Ivana1,2
1Faculty of Agriculture in Osijek, Kralja Petra Svačića 1d, 31000 Osijek, Croatia ()
2Student, Graduate study
Abstract
The aim of the study was to determine allelopathic effect of water extracts fromPolygonumlapathifoliumL. on germination and initial growth of soybean. Water extracts from dry stems and leaves of P. lapathifolimat 0, 1, 5 and 10% concentrations were examined under laboratory conditions using Petri dishes. Results showed that germination was not significantly affected when extracts were applied. Inhibition of root length of soybean seedlings ranged from 36.2 to 71.2%. Higher concentrations (5 and 10%) of both extracts significantly reduced, while 1% leaf extract showed stimulatory effect on soybean root length. With the increase of extract concentration, shoot length and fresh weight of soybean seedlings proportionately decreased, on average for 32.9 and 34.7%, respectively.
Key words: allelopathy, Polygonum lapathifoliumL., water extracts, soybean
Introduction
Allelopathy is defined as any direct or indirect harmful or beneficial effect of one plant, fungus or microorganism on the other ones through production of allelochemicals that escape into the environment (Rice, 1984).Allelochemicals are present in all plant tissues, including leaves, stems, roots, rhizomes, flowers, seeds and pollen, and they can be released into the environment through volatilization, leaching, root exudation and decomposition of plant residues (Putnam and Tang, 1986).Allelopathyplays an important role in agroecosystems leading to a wide array of interaction between weeds and crops (Singh et al., 2001). The release of allelochemicals in soil inhibits seed germination, growth and establishment of agricultural crops and vegetation (Aldrich and Kramer, 1997).
Pale persicaria(PolygonumlapathifoliumL.) is an annual weed that occurs in row crops, cereals and ruderal habitats, usually on damp and nitrogen-rich soils (Knežević, 2006). Souto and al. (1990) reported that P. lapathifoliumhas highallelopathic potential against white clover and lettuce.
The objective of this study was to determine the allelopathic effect of different concentrations of water extracts from dry stems and leaves of pale persicaria (P.lapathifolium) on soybean.
Materials and methods
The experiment was conducted in 2013 in the Laboratory of Phytopharmacy and Plant Systematics at the Faculty of Agriculture in Osijek.
Aboveground mass of pale persicaria wascollected during 2012 at the phenological stage 6/65of the weeds (Hess et al., 1997)from soybean fields and separated in laboratory into stem and leaf. Fresh plant parts were shade dried, cut into small pieces and ground separately with electronic grinder into fine powder. Water extracts were prepared according to Norsworthy (2003) by mixing 100 g of plant powderwith 1000 ml of distilled water, after which the mixture was kept for 24 h at room temperature. The mixture was filtered through muslin cloth to remove debris and after that through filter paper. The obtained stem and leaf extracts were diluted with distilled water to give final concentrations of 1, 5 and 10% (10, 50 and 100 g of biomass per litre).
Soybean seed (cultivar Korana) from Agricultural Institute Osijek was used in the germination test. The seeds were surface-sterilized for 20 min with 1% NaOCl (4% NaOCl commercial bleach), then rinsed three times with distilled water (Siddiqui et al., 2009). Ten seeds were placed in sterilized Petri dishes (10 cm in diameter) on top of filter paper. In each Petri dish 8 ml of extract was added, while distilled water was used in control. Petri dishes were kept at room temperature (22 °C ± 2 °C) for eight days, observed daily and additional extract/water was added to each as needed.All treatments had four replications and experiment was conducted twice.
Germinated seeds were counted daily for eight days. Germination percentage was calculated for each replication using the formula: G = (Germinated seed/Total seed) x 100.Mean germination time (MGT) was calculated according to the equation of Ellis and Roberts (1981): MGT = ∑ (Dn) / ∑ n, where n is the number of seeds that emerged on day D, and D is number of days counted from the beginning of germination.After eight days seedling root length (cm), shoot length (cm) and fresh weight (g) were determined. The collected data were analysed statistically with ANOVA and differences between treatment means were compared using the LSD-test at probability level of 0.05.
Results and discussion
Water extracts from stem and leaf of P. lapathifoliumdid not show significant inhibitory effect on the seed germination of soybean (Figure 1). The increase of extract concentration resulted in reduction of germinated seed percentage, but only up to 6.5%.
Figure 1. Effect of different concentrations of stem and leaf extracts of P. lapathifoliumon soybean germination (%)
Aleksieva and Marinov-Serafimov (2008) and Verma and Rao (2006) reported diverse effects of extracts from weeds which are associated with soybean on its germination. In most cases, germination of soybean was reduced only slightly, but on the other hand, germination of certain soybean cultivars was reduced for over 70%.
Stem extract had no influence on mean germination time of soybean (Figure 2). On the contrary, mean germination time was increased in treatments with leaf extract and was greatest with 10% concentration.
Figure 2. Effect of different concentrations of stem and leaf extracts of P. lapathifoliumon soybean mean germination time (in days)
The results revealed that the inhibition of growth parameters of seedlings was more pronounced than that of seed germination. Inhibition of root length of soybean seedlings ranged from 36.2 to 71.2% (Figure 3). The increase of concentration of both extracts to 5 and 10% significantly reduced root length. On the other hand, the lowest concentration of stem extract only slightly reduced root length, while the lowest concentration of leaf extract stimulated root length for 3.3%. Inhibitory effect of higher and stimulatory effect of lower concentrations of weed water extracts was also reported by Marinov-Serafimov (2010).
Figure 3. Effect of different concentrations of stem and leaf extracts of P. lapathifoliumon root and shoot length (cm) of soybean seedlings
Shoot length (cm) of soybean was reduced with both extracts and decreased proportionately as concentration of weed biomass in water extract increased. The 10% concentration of stem and leaf extract inhibited shoot length for 49.5 and 50.4%, respectively. Similarly, Verma and Rao (2006) found significant reduction of shoot length of soybean with extracts from various weeds. The mechanism of inhibition on the seedling growth caused by allelochemicals can be result of reduced cell division (Iman et al, 2006).
Figure 4. Effect of different concentrations of stem and leaf extracts of P. lapathifoliumon soybean fresh weight (% of control)
Water extracts from stems and leaves of pale persicaria had suppressive effect on fresh weight of soybean seedlings, which was reduced by 16.1 to 53.6% (Figure 4).As well as shoot length, with the increase of the concentration of the extracts, fresh weight of seedlings significantly decreased compared to the control.Aleksieva and Marinov-Serafimov (2008) also reported reduction in accumulation of fresh biomass in soybean seedlings.
Conclusions
Water extracts from stem and leaf of P. persicaria had no inhibitory effect on soybean germination. Root length of seedlings reduced with extracts at two higher concentration levels, on average for 53.5 and 56.9% with stem and leaf extract, respectively. With the increase of extract concentration, shoot length and fresh weight of soybean seedlings proportionately decreased. The inhibition effect was more pronounced on seedling growth rather than on germination of soybean.
References
-Aldrich, R.J., Kremer, R.J. (1997): Principles in Weed Management. 2nd Edition. Iowa State University Press.
-Aleksieva, A., Marinov – Serafimov, P. (2008): A study of allelopathic effect of Amaranthusretroflexus(L.) and Solanumnigrum(L.) in different soybean genotypes. Herbologia, 9(2): 47-58.
-Ellis, R.A., Roberts, E.H. (1981): The quantification of ageing and survival in orthodox seeds. Seed Science and Technology, 9: 373-409.
-Hess, M., Barralis, G., Bleiholder, H., Buhr, H., Eggers, T., Hack, H., Stauss, R.(1997): Use of the extended BBCH scale – general for the description of the growth stages of mono- and dicotyledonous species. Weed Research, 37: 433-441.
-Norsworthy, J.K.(2003):Allelopathic Potential of Wild Radish (Raphanus raphanistrum). Weed Technology, 17: 307-313.
-Iman, A., Wahab, S., Rastan, M., Halim, M. (2006): Allelopathic effect of sweet corn and vegetable soybean extracts at two growth stages on germination and seedling growth of corn and soybean varieties. Journal of Agronomy, 5: 62-68.
-Knežević, M. (2006): Atlas korovne, ruderalneitravnjačkeflore. Poljoprivrednifakultet, Osijek.
-Marinov-Serafimov, P. (2010): Determination of Allelopathic Effect of Some Invasive Weed Species on Germination and Initial Development of Grain Legume Crops. Pesticides and Phytomedicine, 25(3): 251-259.
-Putnam, A.R., Tang, C.S. (1986): The Science of Allelopathy. Wiley, New York.
-Rice, E.L. (1984): Allelopathy. 2nd edition. Academic Press, Orlando, Florida.
-Siddiqui, S., Bhardwaj, S., Khan, S.S., Meghvanshi, M.K. (2009): Allelopathic Effect of Different Concentration of Water Extract of Prosopsis Juliflora Leaf on Seed Germination and Radicle Length of Wheat (Triticum aestivum Var-Lok-1). American-Eurasian Journal of Scientific Research, 4(2): 81-84.
-Singh, H.P., Batish, D.R., Kohli, R.K.(2003):Allelopathic interactions and allelochemicals: New possibilities for sustainable weed management. Critical review in Plant Sciences, 22: 239-311.
-Souto, X.C., González, L., Reigosa, M. (1990): Preliminary study of the allelopathic potential of twelve weed species. Actas de la Reunión de la Sociedad Española de Malherbología, 199-206.
-Verma, M., Rao, P.B. (2006): Allelopathic effect of four weed species extracts on germination, growth and protein in different varieties of Glycine max (L.) Merrill. Journal of Environmental Biology, 27(3): 571-577.
Sažetak
AlelopatskiutjecajkorovnevrstePolygonumlapathifoliumL. naklijavostipočetniporastsoje
Cilj istraživanja bio je utvrditi alelopatski utjecaj vodenih ekstrakata korovne vrste PolygonumlapathifoliumL. na klijavost i početni porast soje. U laboratoriju u petrijevim zdjelicama ispitani su ekstrakti pripremljeni od suhe mase stabljike i lista vrste P. lapathifoliumu koncentracijama od 0, 1, 5 i 10%. Rezultati su pokazali da vodeni ekstrakti nisu značajno utjecali na klijavost soje. Inhibicija duljine korijena klijanaca iznosila je od 36,2 do 71,2%. Više koncentracije (5 i 10%) oba ekstrakta značajno su smanjile duljinu korijena, dok je 1% ekstrakt lista stimulirao rast korijena. S povećanjem koncentracije ekstrakata duljina i svježa masa klijanaca soje se proporcionalno smanjivala, u prosjeku za 32,9 odnosno 34,7%.
Ključne riječi: alelopatija, PolygonumlapathifoliumL., vodeni ekstrakti, soja