ASSESSMENT OF ALLELOPATHIC EFFECT OF PALE PERSICARIA ON TWO SOYBEAN CULTIVARS *

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1 Herbologia, Vol. 15, No. 1, 2015 DOI /Herb ASSESSMENT OF ALLELOPATHIC EFFECT OF PALE PERSICARIA ON TWO SOYBEAN CULTIVARS * Ivan Treber*, Renata Baličević, Marija Ravlić Faculty of Agriculture, Josip Juraj Strossmayer University of Osijek, Kralja Petra Svačića 1d, Osijek, Croatia, corresponding author: mravlic@pfos.hr *Student, Graduate study Abstract The experiment was conducted to assess allelopathic potential of water extracts from weed species pale persicaria (Polygonum lapathifolium L.) on germination and initial growth of two soybean cultivars (Ika and Sanda). Water extracts from dry stems and leaves of P. lapathifolium in concentrations of 1, 5 and 10% were examined under laboratory conditions using Petri dishes. Results showed that soybean cultivars differed both in their response and sensitivity to allelopathic effect of pale persicaria extracts. Overall, cultivar Ika was more susceptible than cultivar Sanda. On average, germination of soybean was not significantly affected by extracts. The highest germination reduction was recorded with 5% leaf extract for 10.1%. However, Sanda germination was slightly more affected. Contrary, extracts showed greater effect, both stimulatory and inhibitory, on root and shoot length and fresh weight of Ika. Both stem and leaf extracts in 10% concentration had the highest inhibitory effect, up to 48.8%. The increase in extract concentration exhibited higher inhibitory effect, while the lowest concentration generally stimulated soybean growth. Keywords: allelopathy, water extracts, weed, Polygonum lapathifolium L., soybean Introduction Interaction between plants in the ecosystems by chemical exudation into the environment, both stimulatory and inhibitory, is defined as allelopathy (Rice, 1984). All plant tissues, including leaves, stems, roots, rhizomes, flowers, seeds and pollen, can contain allelochemicals which can be released through volatilization, leaching, root exudation and decomposition of plant residues (Putnam and Tang, 1986). Leaves are generally the main parts for production of allelopathic substances and their action is maximal (Sisodia and Siddiqui, 2010). Allelopathy is a dynamic process Copyright 2015 by the Academy of Sciences and Arts of Bosnia and Herzegovina.

2 Treber et al. that involves interaction between weeds and crop plants in the agrophytocenoses, under the influence of number of factors - climate conditions, soil type, temperature, precipitation, solar radiation, nutrients, previous crops, accompany crops, diseases, pests and many other factors are determinants of the occurrence of allelopathic interaction (Marinov-Serafimov et al., 2013). Identification of allelopathic properties of weeds and their effect on crops leads to a better understanding of weed species and reduction of negative impact of allelochemicals on growth and yield of crops. Allelopathy also has the potential to be used in breeding programmes for biological control of against weeds through development of less susceptible genotypes or ones with high allelopathic potential (Ebana et al., 2001). Differences among genotypes and cultivars were discovered in many crops, both in crops sensitivity to different weed species, e.g. in soybean and maize (Aleksieva and Marinov-Serafimov, 2008, Baličević et al., 2014), and in crop allelopathic potential against weeds, e.g. in sorghum and sunflower (Alsaadawi and Dayan, 2009, Alsaadawi et al., 2012). Pale persicaria (Polygonum lapathifolium L.) is an annual weed of row crops, cereals and ruderal habitats, grows usually on damp and nitrogen-rich soils (Knežević, 2006) and occurs in soybean crops (Knežević et al., 2012). In our previous study (Baličević et al., 2013) we determined effect of pale persicaria water extracts on soybean cultivar Korana (maturity group 00). Since allelopathic effect can vary between genotypes, the objective of the study is to determine allelopathic effect of pale persicaria water extracts on germination and initial growth of two soybean cultivars from different maturity groups (0, 0-I). Materials and methods The experiment was conducted in 2014 in the Laboratory of Phytopharmacy at the Faculty of Agriculture in Osijek. The plants of pale persicaria were collected at the phenological stage 6/65 of the weeds (Hess et al., 1997) from naturally infested field in Osijek-Baranja County. The aboveground mass of plants was separated in the laboratory into stem and leaf. Fresh plant parts were oven dried, cut into 1 cm pieces and ground separately with electronic grinder into fine powder. Water extracts were prepared according to Norsworthy (2003) by soaking 100 g of plant powder in 1000 ml of distilled water, after which the mixture was kept for 24 h at room temperature. The mixtures were filtered through muslin cloth to remove debris and after that through filter paper. 32

3 Assessment of allelopathic effect of pale persicaria on two soybean cultivars 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 weed biomass per 1000 ml). Seeds of two soybean cultivars, Sanda (maturity group 0) and Ika (maturity group 0-I) (Agricultural Institute Osijek), were used in the germination test. The seeds were surface-sterilized prior to the experiment for 20 min with 1% NaOCl (4% NaOCl commercial bleach), then rinsed three times with distilled water (Siddiqui et al., 2009). In sterilized Petri dishes (10 cm in diameter) ten seeds of soybean were placed on top of filter paper. In each Petri dish 8 ml of certain extract was added, while distilled water was used in control. Petri dishes were kept at room temperature (22 C ± 2 C) for eight days. All treatments had four replications and experiment was conducted twice. After eight days at the end of the experiment the following characteristics were measured: germination, seedling root and shoot length (cm) and fresh weight (g). Germination percentage was calculated for each replication using the formula: G = (Germinated seed/total seed) x 100. The collected data were analysed statistically with ANOVA and differences between treatment means were compared using the LSD-test at probability level of Results and discussion Water extracts from stem and leaf of P. lapathifolium had both stimulatory and inhibitory effect on soybean germination, but not significant compared to control (Figure 1). On average, percent of inhibition ranged from 0.1 to 10.1%. Soybean cultivars differed slightly in their susceptibility to water extracts, and germination reduction of Sanda was somewhat greater (11.2%) than Ika (4.3%). Differences were observed in treatment with lowest concentration of stem extract in which germination of Ika was stimulated for 15.6%, and of Sanda reduced for 18.1%. 33

4 Treber et al. Figure 1. Effect of P. lapathifolium water extracts on soybean germination (%) Root length of soybean seedlings was affected by water extracts (Table 1). On average, suppression of root length was greatest with the highest concentration of both stem and leaf extract, up to 38.8 and 26.1%, respectively. On the other hand, lowest concentrations stimulated root length for over 38% compared to the control. Cultivar Ika was more susceptible to negative effect of water extracts and root length was inhibited on average for 31.1%. Stem and leaf extract in 10% concentration showed the greatest inhibitory effect, while the lowest concentrations had significant stimulatory effect. Root length of Sanda was not significantly affected, with the exception of 1% leaf extract which stimulated root growth for 77.3% compared to the control. Extracts exhibited stimulatory and inhibitory effects on shoot length of soybean seedlings (Table 1). No significant differences were observed in cultivar Sanda where the highest decrease in shoot length was with 10% stem extract (19.1%). Similarly, shoot length of cultivar Ika was reduced significantly only with the highest extract concentration of stem and leaf, but to a larger extent for 31.5 and 29.9%, respectively. On average, fresh weight of soybean seedlings significantly increased only with lower concentration of stem extract (Figure 2). Cultivar Ika was influenced more by extracts, especially with the lowest concentration of extracts. On the other hand, none of the treatments showed significant effect on fresh weight of Sanda seedlings. 34

5 Assessment of allelopathic effect of pale persicaria on two soybean cultivars Table 1. Effect of P. lapathifolium water extracts on root and shoot length (cm) of soybean Treatment Root length (cm) Sanda Control 2.03 b 3.34 c Stem 1% 2.52 b (+24.1) 4.89 a (+46.4) Stem 5% 2.57 ab (+26.6) 3.51 bc (+5.1) Stem 10% 1.58 b (-22.2) 1.71 e (-48.8) Leaf 1% 3.60 a (+77.3) 4.51 ab (+35.0) Leaf 5% 2.23 b (+9.9) 3.09 cd (-7.5) Leaf 10% 1.86 b (-8.4) 2.10 de (-37.1) Treatment Shoot length (cm) Sanda Ika Control 2.83 a 3.08 abc Stem 1% 2.75 a (-2.8) 3.39 ab (+10.1) Stem 5% 2.93 a (+3.5) 2.81 bcd (-8.8) Stem 10% 2.29 a (-19.1) 2.11 d (-31.5) Leaf 1% 2.59 a (-8.5) 3.74 a (+21.4) Leaf 5% 2.42 a (-14.5) 2.56 c (-16.9) Leaf 10% 2.74 a (-3.2) 2.16 d (-29.9) Values in the parenthesis indicate% increase (+) or decrease (-) over control; a,b,c means followed by the same letter within the column are not significantly different at P Ika Figure 2. Effect of P. lapathifolium water extracts on fresh weight of soybean seedlings (g) 35

6 Treber et al. Allelopathic effect of pale persicaria water extracts on soybean was previously reported in our study (Baličević et al., 2013). Extracts showed no significant effect on germination, but showed slight stimulatory and considerable inhibitory effect on root and shoot length and fresh weight of soybean cultivar Korana. In current study, results indicated that cultivars Sanda and Ika differed in their response to allelopathic effect of pale persicaria extracts. Germination of Sanda was more suppressed than germination of Ika. Contrary, extracts showed greater effect, both stimulatory and inhibitory, on root and shoot length and fresh weight of Ika. Differences between cultivars sensitivity was determined by others. Aleksieva and Marinov-Serafimov (2008) studied allelopathic effect of weed species A. retroflexus and S. nigrum on eight different soybean genotypes. The studied varieties exhibited different susceptibility to the effect of extracts due to their genetic differences. Differences observed were depended on soybean maturity group, and were recorder within the maturity groups themselves. Similarly, Verma and Rao (2006) determined differences between six soybean cultivars in their response to allelopathic effect of water extracts from various weed species. Susceptibility depended on both weed species and cultivar. According to Baličević et al. (2014) maize hybrids differed in their susceptibility to water extracts of Convolvulus arvensis. Inhibition of germination for Bc 574 hybrid amounted to 24.9%, while the OSSK hybrid germination was reduced for 50.7%. Genotypic variation in tolerance to allelopathy has been found in other crop-allelopathic plant interactions, such as wheat and rice (Bashir et al., 2012). Generally, with the increase of weed biomass in water seedling growth decreased and the highest concentration of water extracts exhibited the greatest inhibitory effect. Lower concentration on the other hand generally had stimulatory effect. This is in agreement with results of others who also reported inhibitory effect of higher and stimulatory effect of lower concentrations of water extracts (Marinov-Serafimov, 2010, Baličević et al., 2013). When comparing extracts from different plant parts, result showed that both stem and leaf extract had equal effect on germination and shoot length of soybean seedlings. Stem extract had greater inhibitory effect on root length, while fresh weight was more supressed with leaf extract. Both leaves and stems of weeds usually have the highest allelopathic potential among plant parts which is attributed to the presence of higher concentration of allelochemicals (Ravlić et al., 2012, Šćepanović et al., 2007). 36

7 Assessment of allelopathic effect of pale persicaria on two soybean cultivars Conclusions Application of pale persicaria extracts showed both positive and negative effect on soybean germination and growth which depended on plant part, extract concentration and soybean cultivar. Less susceptible cultivars could be used in highly weed infested fields. Besides, stimulatory effect of lower concentrations of extracts could be further investigated and possibly exploited to promote crop growth. However, since experiment was conducted only in Petri dishes, pot and field experiments are necessary to fully identify extract potential. References ALEKSIEVA, A., P. MARINOV-SERAFIMOV, 2008: A study of allelopathic effect of Amaranthus retroflexus (L.) and Solanum nigrum (L.) in different soybean genotypes. Herbologia, 9(2), ALSAADAWI, I.S., A.K. SARBOUT, L.M. AL-SHAMMA, 2012: Differential allelopathic potential of sunflower (Helianthus annuus L.) genotypes on weeds and wheat (Triticum aestivum L.) crop. Archives of Agronomy and Soil Science, 58, ALSADAAWI, I.S., F.E. DAYAN, 2009: Potentials and prospects of sorghum allelopathy in agroecosystems. Allelopathy Journal, 24, BALIČEVIĆ, R., M. RAVLIĆ, D. GORIČKI, I. RAVLIĆ, 2013: Allelopathic effect of Polygonum lapathifolium L. on germination and initial growth of soybean. In: Jug, I., Đurđević, B. (eds) Proceedings and abstracts of the 6th International Scientific/Professional Conference Agriculture in Nature and Environment Protection, Glas Slavonije, Osijek, pp BALIČEVIĆ, R., M. RAVLIĆ, M. KNEŽEVIĆ, I. SEREZLIJA, 2014: Allelopathic effect of field bindweed (Convolvulus arvensis L.) water extracts on germination and initial growth of maize. The Journal of Animal and Plant Sciences, 24(6), BASHIR, U., A. JAVAID, R. BAJWA, 2012: Allelopathic effects of sunflower residue on growth of rice and subsequent wheat crop. Chilean Journal of Agricultural Research, 72, EBANA, K., W. YAN, R.H. DILDAY, H. NAMAI, K. OKUNO, 2001: Variation in the Allelopathic Effect of Rice with Water Soluble Extracts. Agronomy Journal, 93, HESS, M., G. BARRALIS, H. BLEIHOLDER, H. BUHR, T. EGGERS, H. HACK, R. STAUSS, 1997: Use of the extended BBCH scale general for the description of the growth stages of mono- and dicotykedonous species. Weed Research, 37, KNEŽEVIĆ, M., 2006: Atlas korovne, ruderalne i travnjačke flore. Sveučilište Josipa Jurja Strossmayera u Osijeku, Poljoprivredni fakultet u Osijeku, Osijek. KNEŽEVIĆ, M., R. BALIČEVIĆ, M. RAVLIĆ, J. RAVLIĆ, J. 2012: Impact of tillage systems and herbicides on weeds and soybean yield. Herbologia, 13(2), MARINOV-SERAFIMOV, P., 2010: Determination of Allelopathic Effect of Some Invasive Weed Species on Germination and Initial Development of Grain Legume Crops. Pesticides & Phytomedicine, 25, MARINOV-SERAFIMOV, P., T. DIMITROVA, I. GOLUBINOVA, 2013: Allelopathy element of overall strategy for weed control. Acta Agriculturae Serbica, 18(35), NORSWORTHY, J.K., 2003: Allelopathic Potential of Wild Radish (Raphanus raphanistrum). Weed Technology, 17,

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