EFFECT OF ALLELOPATHIC LEAF EXTRACT OF SOME SELECTED WEED FLORA OF AJMER DISTRICT ON SEED GERMINATION OF TRITICUM AESTIVUM L. Gupta Ankita 1 and Mittal Chabbi 2 1 Research Scholar, Dept. of Botany, Govt. College, Ajmer (Rajasthan) India. 2 Dept. of Botany, Govt. College, Ajmer (Rajasthan) India. gupta.ankita83@gmail.com ABSTRACT The present study was conducted to investigate the allelopathic effects of some selected weeds (Phalaris minor L., Chenopodium muralel., Sonchus oleraceus L., Cyanodon dactylon L. and Convolvulus arvensis L.) of Ajmer district on seed germination and seedling growth of wheat(triticum aestivum L.). Root, stem and leaf aqueous extracts of weeds at 2, 4, 6, 8, 10% concentrations were applied to determine their effect on seed germination, seedling length and seedling dry weight of test plant under laboratory conditions. The aqueous extracts of all the weeds under study caused inhibitory effects on seed germination; seedling length and seedling dry weight of crop, which increased progressively on increasing the concentration of weed plant part extracts. The leaf extract of Phalaris minor have more inhibitory effect on the germination percentage of crop as compared to other weeds under study. The inhibition caused by the leaf extract of Phalaris minor was found to be more than stem and root extracts of all the weeds under study. Keywords: Allelopathic, seed germination and weeds. INTRODUCTION Weeds are the most severe and widespread biological constraint to crop production and cause invisible damage till the crop is harvested. Weeds are undesirable plants which compete with main crops in the growth media for nutrients, moisture, space, light and hamper the healthy growth ultimately reducing the growth and yield both qualitatively and quantitatively. Rice (1974) defined allelopathy as any direct or indirect harmful effect by one plant to another through the production of chemical compounds, which escape into the environment. Allelopathic substances are most commonly found in plant extracts and in plant residues of soil, some are found in live plant exudates and as volatile gases liberated from leaves and rhizome (Keeley, 1987). Weeds are known to exhibit allelopathy by releasing watersoluble allelochemicals from leaves, stems, roots, rhizomes, flowers, fruits and seeds (Alam et al., 1990; Ahn & Chung, 2000; Batish et al., 2007a, 2007b; Duke et al., 2007; Le Tourneau et al., 1956; Rice, 1984). Allelochemicals emancipated as residues, exudates and leachates by many plants from leaves, stem, roots, fruit and seeds reported to interfere with growth of other plants (Asgharipour and Armin, 2010). These chemicals products mainly affect plants at seed emergence and seedling levels (Alam and Islam, 2002; Hussain et al., 2007; Mohamadi and Rajaie, 2009; Naseem et al., 2009). The allelopathic potential of several weeds have been studied in the laboratory (Azmi & Alam, 1989; Bhowmik & Doll, 1984; Kato-Noguchi et al., 2002). Batish et al., (2007b) conducted experiment using residue of Chenopodium murale on the growth of chickpea and pea and found that their root and shoot length significantly decreased. Le Tourneau et al., (1956) found that water extracts from 23 common weeds and crop residues inhibited germination and growth of wheat seedling. In weed research, one of the main purposes of studies on allelopathy is to gain insight into the mechanisms of weed/crop interactions and to utilize such information for improving the weed management strategies (Purvis, 1990). The objective of this study was to ascertain the effects of aqueous extracts of weed plant parts on seed germination, seedling growth and seedling dry weight of crop (Majeed et al., 2012). http://jsrr.in 311 ISSN: 2249-7846 (Online)
Gupta and Mittal MATERIALS AND METHODS Leaves, stem and root of field grown weed plants (Phalaris minor L., Chenopodium murale L., Sonchus oleraceus Fig., Cyanodon dactylon L. and Convolvulus arvensis L.) were collected and washed to remove soil particles, cut into pieces and air dried. The dried plant parts were ground separately in a grinder and after sieving, stored in air tight glass bottles. Aqueous extracts of leaf, stem and root were prepared by adding 10 gm of air dried weed plant material in 100 ml of distilled water kept for 24 hrs at room temperature. It was filtered through Whatman filter paper no. 1 and the volume of the filtrate made to 100ml (Dhawan and Narwal, 1994). Different dilutions such as 2%, 4%, 6% and 8% of the extract were prepared from this stock solution. Glass petridish (9.0 X 1.5 cm) were used to study the allelopathic effect of aqueous extract and distilled water as a control on the germination, seedling growth in the form of seedling length and seedling dry weight of crops. The seeds of Triticum aestivum L. were soaked in distilled water overnight. Next day the seeds were surface sterilized with 0.1 percent mercuric chloride solution for two minutes and washed twice with distilled water and kept for germination. Paper towels were used for germination tests and the towel was wrapped with the tissue paper. Each paper towel was moistened with approximately 10 ml. of respective extracts. A control set in two replications, i.e. paper towel moistened with distilled water was maintained along with the sets of different concentrations viz, 10%, 8%, 6%, 4% and 2% respectively. In each set of treatment two replicates were kept containing 10 seeds each respectively. These experimental paper towels were kept in laboratory conditions and observation of germination percentage, seedling length and seedling dry weight was done after an interval of one week. RESULTS AND DISCUSSION Effects of different concentrations of Phalaris minor L., Chenopodium murale L., Sonchus oleraceus, Cyanodon dactylon L. and Convolvulus arvensis L. extracts on seed germination, seedling growth and seedling dry weight of Triticum aestivum L., were studied. Fig. 1 Fig. 2 Fig. 3 Fig. 1: Effect of 8% and 10 % aqueous leaf extract of Phalaris minor L. on Triticum aestivum L. Fig. 2: Effect of 6% aqueous leaf extract of Phalaris minor L. on Triticum aestivum L. Fig. 3: Effect of 4% aqueous leaf extract of Phalaris minor L. on Triticum aestivum L. Fig. 4 Fig. 5 Figure 4: Effect of 2% aqueous leaf extract of Phalaris minor L. on Triticum aestivum L. Figure 5: Effect of distilled water on Triticum aestivum L. http://jsrr.in 312 ISSN: 2249-7846 (Online)
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Gupta and Mittal Concerning the germination rate, data of all target species demonstrated a significant degree of suppression and a negative response to the increasing concentration of different weed extracts (Table 1-15, Fig. 1-5). There were significant differences between the test treatments and control. The leaf extract of Phalaris minor has more negative effects on the germination rate, seedling length and seedling dry weight than the stem and root extracts of all the weeds studied. Suppressive effect was increased with an increase in extract concentration indicating that the effect of plant extracts depends very much on their concentration. Similar observation was found by Ballester et al., (1982); Rizvi and Rizvi (1987); Bansal (1998); Daniel (1999); Turk et al., (2003). Maximum inhibition was shown by Phalaris minor on Triticum aestivum L. seed germination, seedling length and seedling dry weight (Table 1-3). The chemical exudates from allelopathic plants are proposed to play a major role in the allelopathic mode of action. Allelopathic effect of these compounds is often observed to occur early in the life cycle causing inhibition of seed germination and/or seedling growth. Evidence shows that a higher plant releases a diversity of allelochemicals into the environment, which include phenolics, alkaloids, long - chain fatty acids, terpenoids and flavanoids (Rice, 1984 and Chou, 1995). The compounds exhibit a wide range of mechanisms of action, affect on DNA (alkaloids), photosynthetic and mitochondrial function (quinines), phytohormone activity, ion uptake and water balance (phenolics) (Einhellig, 2002). In addition, the allelochemicals are an important defense for certain plants against the interference of other plants of the same or different species, which can affect their growth and development (Larcher, 2000 and Uremis et al., 2009). LITERATURE CITED Agarwal A, Gahlot A, Verma R and Rao P, 2002. Effects of weed extracts on seedling growth of some varieties of wheat. Journal of Environmental Biology, 23: 19-23. Alam SM and Islam EU, 2002. Effect of aqueous extract of leaf, stem and root of nettle leaf goosefoot and NaCl on germination and seedling growth of rice. Pakistan Journal of Science and Technology, 1 (2): 47-52. Alam SM and Shaikh AH, 2007. Influence of leaf extract of Nettle Leaf Goosefoot (Chenopodium murale L.) and Nacl salinity on germination and seedling growth of rice (Oryza sativa L.). Pak. J. Bot.,39(5): 1695-1699. Asgharipour MR and Armin M, 2010. Inhibitory effects of Sorghum halepens root and leaf extracts on germination and early seedling growth of widely used medicinal plants. Advances in Environmental Biology 4 (2): 316-324. Ballester A, Vieitez AM and Vieitez E, 1982. Allelopathic potential of Erica vegans, Callunga vulgaris and Daboecia cantabrica. J. Chem. Ecol. 8: 851-857. Batish DR, Lavanya K, Singh HP and Kohli RK, 2007. Root-mediated allelopathic interference of nettleleaved goosefoot (Chenopodium murale) on wheat (Triticum aestivum). J. Agronomy and Crop Science 193: 37 44. Beres IO and Cazinczi G, 2000. Allelopathic effects of shoot extracts and residues of weeds on field crops. Allelop J., 7: 93-98. Bhowmik PC and Doll JD, 1984. Allelopathic effects of annual weeds residues on growth and nutrient uptake on corn and soybean. Agron J., 76:383-388. Channappagodar BB, Jalageri BR and Biradar NR, 2003. Allelopathic effects of aqueous extracts of weed species on germination and seedling growth of some crops. Karnataka Journal of Agriculture Science, 18 (4): 916-920. Dongre PN, Singh AK. 2007. Inhibition effects of weeds on growth of wheat seedlings. Allelopathy J., 20(2): 387-394. Hossain MK and Alam MN, 2010. Allelopathic effects of Lantana camara leaf extract on germination and growth behaviour of some agricultural and forest crops in Bangladesh. Pak. J. Weed Sci. Res. 16 (2): 217-226. Hussain S, Siddiqui S, Khalid S, Jamal A, Qayyum A and Ahmed Z, 2007. Allelopathic potential of Senna (Cassia angustifolia ) on germination and seedling characters of some major cereal crop and their associated grassy weeds. Pak. J. Bot. 39: 1145-1193. http://jsrr.in 314 ISSN: 2249-7846 (Online)
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