Academia Journal of Agricultural Research 2(3): 74-79, March 214 DOI: http://dx.doi.org/1.15413/ajar.213.174 ISSN: 2315-7739 214 Academia Publishing Research Paper Studies on the allelopathic effect of aqueous extract of Ageratum conyzoides Asteraceae L. on seedling growth of Sorghum bicolor Linn. (Poaceae) Accepted 9 th January, 214 ABSTRACT MacDonald Idu Department of Plant Science and Biotechnology, University of Benin, P.M.B 1154, Benin City Nigeria. macdonaldidu@hotmail.com mcdonald.idu@gmail.com +23485679 The effect of aqueous stem, leaves, flowers and root extracts of Ageratum conyzoides on seedling growth, percentage germination and seedling evaluation of Sorghum bicolor at various treatment concentrations (25, 5 and 1) ppm was evaluated. The objective was to determine possible allelopathic effect of A.conyzoides extracts on S. bicolor seedlings cultivated on sandy and loam soil. At the end of this experiment, it was observed that A. conyzoides on both sandy and loamy soil has a low inhibiting effect on sorghum. The result of this study suggest that root exudates and extracts of A. conyzoides suppresses the growth of sorghum by releasing phenolic allelochemicals into the soil rhizosphere and not through alteration of soil nutrients. Further investigation on A. conyzoides is recommended as it can be used as a valuable herbicide by agriculturists as established in the findings of this research. Key words: Allelopathy, Ageratum conyzoides, Sorghum bicolor, Seedling growth, Seedling evaluation. INTRODUCTION Allelopathy has been broadly defined as the production of chemical compounds by one plant species that influences another plant species, mostly in a deleterious way (Newman, 1983; Rice 1984; Lawrence et al., 1991). Allelopathic plants interfere with nearby plants by dispersing chemicals into the soil that may inhibit neighboring plant growth, nutrient uptake, or germination (Inderjit and Dakshini, 1994; Inderjit and Dakshini, 1995, Inderjit, 1996; Abhilasha et al., 28). Allelochemicals are released into the environment via leachates and volatiles from live or dead plant roots and leaves (Jackson and Willenmsen 1976; Rice, 1984; Inderjit and Dakshini, 1994; Inderjit and Dakshini, 1995). Research on the recognition and understanding of allelopathy has been well documented over the past few decades (Rice, 1984; Rizvi et al., 1992). Sorghum bicolor Linn commonly called sorghum is a Poaceae related annual plant used largely for forage and it is very important in the world s human diet, with over 3 million people dependent on it (Bukantis, 198). Sorghum is one of the most important cereal crops in the semi-arid tropics. Sorghum is tolerant to drought, water, logging, saline, alkali, infertile soil and high temperatures. The disease that affects sorghum mostly is the sorghum midge, which is one of the most damaging and widely distributed in all sorghum growing regions of Africa. Sorghum was reported to be antiabortive, cyanogenetic, demulcent, diuretic, emollient, intoxicant, and is a folk remedy for cancer, epilepsy, flux, and stomach-ache (Duke and Wain, 1981). Ageratum conyzoides (Asteraceae) is an erect, herbaceous annual, 3 to 8 cm tall; stems are covered with fine white hairs, leaves are opposite, pubescent with long petioles and include glandular trichomes. The inflorescence contains 3-5 pink flowers arranged as a corymb and are selfincompatible. The fruit is an achene with an aristate pappus and is easily dispersed by wind. In some countries the species is considered a weed, and control is often difficult.
Academia Journal of Agricultural Research; Idu 75 Seeds are positively photoblastic, and viability is often lost within 12 months. The optimum germination temperature ranges from 2 to 5 C. The species has great morphological variation, and appears highly adaptable to different ecological conditions. A. conyzoides is widely utilized as traditional medicine by various cultures worldwide, although applications vary by region. This study is aimed at investigating the possible effect(s) of A. conyzoides aqueous extract on S.bicolor seedling growth on sandy and loamy soil samples. MATERIALS AND METHODS Source of material S. bicolor used in this research work, were obtained from the Katako grain market in Jos, Plateau state of Nigeria, while the A. conyzoides plants was gotten from selected lawns and farmland in Ejeme-Aniogor, in Delta state, Nigeria. Seeds of sorghum (S. bicolor) (red variety) were obtained from katako grain (commodity) market in Jos, Plateau state of Nigeria. The soil sample used in this research was obtained from Ejeme-Aniogor in Delta state. Preparation of test extracts This research work was carried out using aqueous extracts from the stem, leaves, root and flowers of A. conyzoides L. These plant parts were thoroughly washed in distilled water and dried in the oven at 8 C for 24 h. The dried samples were then ground to powder using pestle and mortar and sieved through an 8. mm aperture size wire mesh net screen. Ground samples were kept in plastic bags at room temperature. Three levels (, 25, 5 ppm) each of (stem, leaves, roots and flower) of A. conyzoides L, aqueous extract were prepared for use. The extracts were filtered into 1 ml beakers using Whatman filter paper. Methods used by Alam and Azmi (1991) were employed for the germination and seedling growth study. The treatment at each extract level were arranged randomly and applied thrice. The germinated seeds were counted, while the plumule height, radical length and number of root hair for each germinated seed crops were recorded (that is, Sorghum seed) every day for a period of three months and the results were expressed in terms of the average of the experiment. The data were analyzed statistically using simple percentage to evaluate the treatments effects. Viability test The floatation method was used whereby the seeds were steeped in a volume of water contained in a beaker; the viable seeds sank while those that floated were regarded as non-viable. Seedling evaluation In the evaluation of seedlings of sorghum (red variety), the procedure used by Idu and Ovuakporie-Uvo (213) was followed. Statistic analysis Results were expressed as mean± standard error of mean (S.E.M) and the level of significance between means were computed by ANOVA (F-test) using SPSS 17 computer software package. The level of significance was determined at.5 and data were also analyzed statistically using simple percentage to evaluate treatments. RESULTS The results of this research work are presented in three (3) broad sections namely, effects of extracts on germination, percentage germination and seedling evaluation. Effect of extract In the tables, means with same superscript are not significantly different from each other while means with different superscript are significantly different. Table 1 shows the result of the effect of flower, root, stem and leaves extract respectively on the plumule length development of S. bicolor on sandy and loamy soil at various levels (, 25, 5 and1 ppm). Table 2 shows the result of the effect of flower, root, stem and leaves extract respectively on the radical height development of S. bicolor on sandy and loamy soil at concentrations, 25, 5 and1 ppm. Table 3 shows the result of the effect of flower, root, stem and leaves extract respectively on the number of root hair development of S. bicolor cultivated on sandy and loamy soil at concentrations, 25, 5 and1 ppm. Table 4 shows result of the percentage germination of sorghum using aqueous extract of A. conyzoides cultivated on sandy and loam soil samples. Seedling evaluation was done using parameters such as primary roots, hypocotyls, shoot and primary leaves evaluation. Results are shown in Table 5. DISCUSSION The effect of stem extract on germination of sorghum cultivated on sandy soil shows that an increase in
Academia Journal of Agricultural Research; Idu 76 Table 1. Effect of A. conyzoides aqueous extracts on plumule length of sorghum on sandy and loam soil samples. Extract sources Parameter Concentration in PPM Sandy soil Loamy soil 25 5 1 3.77±.33 a 3.57±.31 a 3.55±.42 a 3.69±.39 a 4.52±.91 b 4.34±.4 b 3.85±.5 b 2.98±.55 a 25 5 1 3.19±.33 a 3.8±.31 a 3.49±.38 a 3.1±.46 a 2.38±.38 a 3.73±.39 a 3.2±.44 a 2.85±.4 a 25 5 1 3.22±.44 b 2.97±.45 a 2.7±.36 a 3.17±.51 b 4.2±.61 b 3.8±.42 a 3.5±.44 a 4.16±.58 b 25 5 1 4.1±.43 a 3.39±.53 a 3.64±.38 a 3.4±.41 a 3.83±.67 a 4.26±.15 a 3.9±.39 a 3.58±.36 a Table 2. Effect of A. conyzoides aqueous extracts on radical height of sorghum cultivated on sandy and loam soil samples. Extract sources Parameter Concentration in PPM Sandy soil Loamy soil 25 5 1 2.2±.49 a 2.2±.49 a 2.4±.42 a 2.7±.3 a 5.67±.28 b 4.53±.66 b 5.4±.83 b 2.86±.63 a 25 5 1 4.27±.72 a 3.59±.69 a 4.93±.7 b 4.24±.57 a 3.64±1.14 a 4.73±.23 a 4.44±.45 a 3.96±.42 a 25 5 1 3.48±.77 a 3.51±.57 a 3.24±.7 a 3.88±1.1 a 3.97±.72 b 3.11±.74 b 2.25±.56 a 4.62±.54 b 25 5 1 4.8±.4 a 4.63±.79 a 4.8±.53 a 4.27±.67 a 6.57±1.15 b 4.27±.21 a 5.31±.64 a 4.22±.62 a concentration increases its plumule length, radicle height, and the number of root hair. The plumule length was least at 25 ppm concentration, and highest at 5 and 1 ppm concentration respectively. The radicle height also had increase at 5 and 1 ppm concentration, least at 25 ppm. The number of root hair had observed increase in germination at concentration 5 and 1 ppm but the least number of root hair was at 25 ppm. For the effect of
Academia Journal of Agricultural Research; Idu 77 Table 3. Effect of A. conyzoides aqueous extracts on the number of root hairs of sorghum cultivated on sandy and loam soil samples. Extract sources Parameter Concentration in PPM Sandy soil Loam soil 25 5 1 1.5±.37 b 1.5±.37 b.9±.28 b 1.1±.46 b 11.9±1.49 b 8.1±1.91 b 12.6±3.75 b 2.1±.85 a 25 5 1 1.4±.52 a 1.2±.53 a 3.9±1.52 b 1.8±1.5 a 2.5±1.2 a 6.2±1.84 b 6.1±2.23 b 3.9±1.83 a 25 5 1 5.9±2.92 a 5.4±1.76 a 5.5±1.83 a 4.±1.61 a 5.3±1.83 b 5.5±2.13 b 4.5±1.47 a 4.8±1.81 a 25 5 1 9.4±2.16 b 5.3±1.57 a 5.3±1.57 a 9.±2.87 b 4.2±1.5 a 4.4±.27 a 4.9±1.21 a 3.3±1.21 a Percentage germination Table 4. shows result of the percentage germination of sorghum using aqueous extract of Ageratum conyzoides cultivated on sandy and loam soil samples. Extract sources Concentration in PPM Sandy soil Loam soil 25 5 1 48.±23.5 a 5.±22.5 a 55.7±25.1 a 53.3±24.7 a 54.7±24.3 a 49.7±19.9 a 45.3±2.2 a 54.±23.5 a 25 5 1 53.3±24.7 a 59.3±26.7 a 54.7±25.8 a 53.3±24.5 a 58.±25. a 44.7±18.9 a 51.±23.1 a 34.7±16.9 a 25 5 1 51.±24. a 57.3±27.2 a 5.±22.9 a 55.±25.5 a 47.±22.3 a 52.±23. a 55.7±24.9 a 57.7±26.6 a 25 5 1 69.7± 4.4 a 45.±21.6 a 5.3±24.2 a 54.±23.5 a 55.±26. a 44.7±2.9 a 3.7±12.9 a 42.3±18.7 a For all the analysis, Means with the same superscript are not significantly different, but means with different superscript are significantly different from each other. Means are not significantly different at 5%. Means for group in homogenous subset are displayed. Seedling evaluation.
Academia Journal of Agricultural Research; Idu 78 Table 5. Seedling evaluation of effects of Ageratum conyzoides extracts on the development of S. bicolor. Conc. (ppm) leaves Soil type Primary root Hypocotyl Primary shoot Sand Negative geotropic Spindle stunted Loam Stubby, retarded, spindle Trapped seed coat Broken in forming loop or spiral Spindly bent over Shredded Deformed missing 25 Sand Stubby, broken Spindly Bent over Deformed missing Loam Trapped seed coat, Glassy Twisted Decayed missing Decayed exiting less 5 Sand Trapped seed coat Stubby, stunted Glassy twisted than and shredded Loam Trapped seed coat geotropic Spindle twisted Glassy Deformed missing 1 Sand Stunted, broken Constricted glassy Twisted bent over Missing Loam Glassy, constricted Missing, shredded Spindly Fractured and deformed leaves extract on germination of sorghum on sand, Plumule length was least at 5 ppm concentration and highest at 25 ppm concentration. Thus, it can be said that increase in concentration increases the plumule length. For radicle height, the greatest effect of A. conyzoides leaf extract was observed at treatment 5 and 1 ppm. Also, an increase in concentration for number of root hair decreases the number of root hair. Effect of leaves extract on germination of sorghum on loams for plumule length and radicle height at 25 and 1 ppm concentration, showed an increase but, a decrease was observed at 5 ppm concentration. The radical height was highest at 1 ppm concentration treatment. The number of root hair had a decrease with increase in concentration. These observations are in conformity with previous research findings (Yang, 1991; Xuan et al., 24; Idu and Ovuakporie-Uvo, 213). The effect of flower extract germination of sorghum on sand was an increase in the length of plumule as the concentration increases. In contrast with the control treatment, the plumule length was the least there. On the radicle height column, it was observed that the more the increase in concentration the more the increase in the radicle length, while for the root hair it was observed that the number of root hair was smallest at 1 ppm concentration and most at 5 ppm concentration when compared with control, the number of root was smallest while, 25, 5 and 1ppm treatment were higher. The effect of flower extract on germination of sorghum cultivated on loam showed that at 25 ppm, plumule length was shortest while at 5 ppm plumule length was longest when compared to all the values obtained. the radicle height was highest at 5 ppm concentration and lowest at 1 ppm concentration, for the number of root it was observed that the more the increase in concentration the less the number of root hair. extract in general had a negative effect on plumule height, radicle lenght and in the number of root hair with increase in concentration. This report corroborates with the findings of Srivastava in 1985 (15 g of aerial part or 3 g of roots in 1 ml during 24 h inhibited germination of wheat and rice seeds). Sorghum cultivated on sand was observed mostly on the 25 ppm treatment, being that the length of plumule was least at this concentration. while for 5 and 1 ppm there was no much effect observed, in that their length were all about the same. For the radicle height, it was observed that the more the concentration, the more the increase in the radicle height, the least height was at 25 ppm concentration while the highest height was obtainable at 1 ppm concentration, while for the number of root hair, it was observed that the more the increase in concentration, the more the number of root hair. Effects of root extract on sorghum on loam; plumule length was reduced mostly at 25 ppm concentration and highest at 5 ppm concentration. On the radicle height column, it was observed that the more the increase in concentration, the more the increase in the radicle height. For the number of root hair, it was observed that increase in concentration increases the number of root hair. On percentage germination of A. conyzoides flower extract on sorghum cultivated on sandy soil, increased at all level of concentration exerted notable effect on the growth of sorghum as shown in Table 4. The effect of A. conyzoides flower aqueous extract on sorghum cultivated on sandy soil was highest at the concentration 25 ppm, and least at concentration 5 ppm. There was reasonable germination with increased concentration that is, the more the concentration, the more the increase in percentage germination of sorghum, when compared with the control treatment. Sorghum on treatment with A. conyzoides aqueous stem extract on sandy soil had increased percentage germination with increase in concentration (that is, 25 and 5). However 1 ppm concentration
Academia Journal of Agricultural Research; Idu 79 had the lowest response to germination with this extract type. For percentage germination using A. conyzoides aqueous leaves extract on sorghum cultivated on sandy soil, the more the concentration, the lesser the percentage germination. Percentage germination using aqueous flower extract of A. conyzoides on loamy soil on sorghum, there was an increase in percentage germination with increase in percentage concentration treatment from 25 to 1 ppm. For percentage germination of aqueous root extract of A.conyzoides on loamy soil, sorghum was observed to have increasing percentage germination with increase in concentration. The percentage germinate was highest at the treatment with 1 ppm concentration. A. conyzoides aqueous stem extract of sorghum cultivated on loamy soil had increase in percentage germination with in concentration from 25, 5 and 1 ppm. A. conyzoides aqueous leaves extract on loam soil; in the sorghum column 25 and 1 ppm concentrations had increased percentage germination compared to the control but, 5 ppm had the least percentage germination. The seedling evaluation of the effect of A. conyzoides revealed that the primary root of S. bicolor was stunted and trapped at 25 and 5 ppm, while at 1 ppm, it was missing, and the hypocotyls was shredded at 1 ppm. The shoot was tightly twisted and bent over at 1 ppm, the primary leaves were missing at 1 ppm (Table 5). The result of this research suggests that A. conyzoides is an allelopathic weed and therefore farm land of economic importance should be completely devoid of A. conyzoides due to its allelopathic effects, which if present on farm land can obviously result in stunted growth and poor yield of agricultural crops. Bukantis R (198). Energy inputs in sorghum production, In: D. Pimentel (Ed.), Handbook of Energy Utilization in Agriculture, CRC Press Inc., Boca Raton, FL, pp.13 18. Duke JA, Wain KK (1981). Medicinal plants of the world. Computer index with more than 85, entries, 3 volumes. pp.1654. Idu M, Ovuakporie-Uvo O (213). studies on the allelopathic effect of aqueous extract of Ageratum conyzoides asteraceae on seedling growth of sesanum indicum l. (pedaliaceae). Int. J. Sci. Environ. Technol. 2(6):1185-1195 Inderjit (1996). Plant phenolic in allelopathy, Bot. Rev. 62:186 22. Inderjit, Dakshini KMM (1994). Allelopathic effects of Pluchea lanceolata on characteristics of four soils and growth of mustard and tomato. Am. J. Bot. 81:799 84. Inderjit, Dakshini KMM (1995). On laboratory bioassays in allelopathy. Bot. Rev. 61:28-44 Jackson JR, Willemsen RW (1976). Allelopathy in the first stages of secondary succession on the piedmont of New Jersey. Am. J. Bot. 63:115 123. Lawrence JG, Colwell A, Sexton OJ (1991). The ecological impact of allelopathy in Ailanthus altissima (Simaroubaceae). Am. J. Bot.78:948 958. Newman EI (1983). Interactions between plants. In Lang OL, Nobel PS, Osmond CB, Ziegler H [eds.], Physiological Plant Ecology III: Responses to the Chemical and Biological Environment. Springer-Verlag, Berlin, FRG. Rice EL (1984). Allelopathy. 2 nd Ed., Orlando,Fl; Academia press, New York, pp.421. Rizvi SJH, Haque H, Singh VK, Rizvi V (1992). A discipline called Allelopathy. pp.1-1. In: Rizvi SJH, Rizvi V. Eds. Allelopathy basic and applied aspects. New York, Chapman and Hall. Srivasta US, Jaiswal AK, Abidi R (1985). Juvenoid activity in extracts of certain plants. Curr. Sci. pp.576-579. Xuan TO, Shinkichi T, Hong NH, Kanh TD Min CI (24). Assessment of phytotoxic action of Ageratum conyzoides L. (Billy goat weed) on weeds. Crop Prot. J. 23:915-922. Yang CM (1991). Allelopathic potential of purple nutsedge. (C. rotundus L.) and barnyard grass [Echinochloa crusgalli (L) Beauv.] on corn (Zea mays L. var. Tainung No.I). Inhibition of weed extracts on germination. Weed Sci. Bull. 12:12-21. Conclusion It be concluded that A. conyzoides extracts (flower, stem, root and leaf) had a positive allelopathic effect on the germination of S. bicolor at all concentrations. It can also be concluded that soil was not a determining factor for consideration of allelopathy of A. conyzoides on the seedling development of selected grain (sorghum), but could be as a result of the inhibitory effect of allelochemicals present in A. conyzoides. The result of this study thus suggests that allelopathy plays a significant role in a root- mediated negative interference of A. conyzoides. REFERENCES Abhilasha D, Quintana N, Vivanco J, Joshi J. (28). Do allelopathic compounds in invasive Solidago canadensis l. restrain the native European flora? J. Ecol. 96:993 11. Alam I, Amzi AR (1991). Effect of purple Nutsedge (Cyperus rotundus) leaf extract on germination and seedling of wheat. Pak. J. Weed Sci. Res. 4:59-61. Cite this article as: Idu M (214). Studies on the allelopathic effect of aqueous extract of Ageratum conyzoides Asteraceae L. on seedling growth of Sorghum bicolor Linn. (Poaceae). Acad. J. Agric. Res. 2(3): 74-79. Submit your manuscript at http://www.academiapublishing.org/journals/ajar