Journal of Life Sciences 5 (2011) 220-223
Allelopathic Potentials of Some Crop Residues on the Germination and Seedling Growth of Chromolaena Odoratum L.
Modupe Janet Ayeni and Joshua Kayode
Department of Plant Science, University of Ado-Ekiti, Ado-Ekiti 361010, Nigeria
Received: October 25, 2010 / Accepted: November 26, 2010 / Published: March 30, 2011.
Abstract: The allelopathic effects of aqueous extracts of rice husk (Orza sativa L.) and sorghum stem (Sorghum bicolor L.) on the germination and edling growth of Chromolaena odoratum L. were investigated. The extracts of the two crop residues exhibited inhibitory effects on the germination and edling growth of Chromolaena odoratum L. The degree of retardation demonstrated in both extracts was concentration dependent. However the results obtained revealed that the retardation was more pronounced in the rice husk extract-treated eds. However statistical analysis (P < 0.05% level) revealed that the degrees of inhibition of radicle and plumule obtained from various extracts treated eds of both extracts were not significantly different when compared to tho obtained from the control experiments as well as tho obtained from the varying extract concentrations.
Key words: Allelopathy, crop residues, germination, edling growth, Chromolaena odoratum.
1. Introduction
Allelochemicals produced by some plants are now known to influence the growth and development of neighboring plants, when they are relead into the environment. The allelochemicals may be prent in various parts of the plant, they can be found in the roots, leaves, flowers, fruits, eds or stems from where they are relead into the soil through various process such as volatilization, root exudation, leaching and decomposition of plant residues [1, 2].
Allelochemicals affect germination and growth of other species by, blocking hydrolysis of nutrient rerve and cell division [3, 4] causing significant reductions in the growth of plumule and radicle of various crops [5], retardation of edling growth and poor edling survival [6, 7].
Modupe Janet Ayeni, M.Sc., rearch fields: plant physiologyandecology.E-mail:****************. Corresponding author: Joshua Kayode, Ph.D., professor, rearch fields: agroforestry and ecology. E-mail: jokayode@
Recent initiatives are now suggesting the u of allelochemicals in weed control particularly now that
the extensive u of herbicides in modern agriculture has given ri to concerns about herbicides residues in the environment and the rapid development of herbicides resistant by weeds. It is now known that over 295 weed biotypes have acquired resistant to important herbicides. Thus non-herbicidal innovation, such as enhancing crop allelopathic ability are increasingly being required in managing weed populations [8]. It is expected that weed suppression by crop allelopathy during the early establishment period would reduce the need for commercial herbicides. Also allelochemicals being biosynthesized herbicides are easily biodegradable and are believed to be much safer than herbicides [9, 10].
In Nigeria, allelopathic studies reported so far had concentrated on the allelopathic potentials of weeds on agricultural crops. Some of the included the studies of Tijani-Eniola and Fawusi [11] on Chromolaena odoratum, Kayode [12-14] on Euphorbia heterophylla
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Allelopathic Potentials of Some Crop Residues on the Germination and Seedling Growth of
Chromolaena Odoratum L.
221
Aspilia africana and Calotropis procera respectively. No study had been reported so far on allelopahic potentials of crop residues in the country. Conquent on the above, the study being reported here aimed at examining the allelopathic effects of aqueous extracts from residues of sorghum stem and rice husks on Chromolaena odoratum, a commonly occuring weed in Nigeria.
2. Materials and Methods
Freshly removed rice husks were obtained from a rice mill situated in Igbemo-Ekiti, a town situated at about 20 km from the campus of the University of Ado Ekiti while mature sorghum stem were harvested from the experimental farm of the Department of Plant Science, University of Ado- Ekiti, Ado-Ekiti, Nigeria. The sorghum stem were cut into small pieces to facilitate drying. The rice husks and sorghum were air dried for three weeks and later pounded using pistil and mortal. Portions of 5 g, 10 g, 15 g, 20 g and 25 g were measured out from rice husks and sorghum residues. Each portion was soaked in 200 mL of distilled water in 500 mL conical flasks. The mixtures were shaken intermittently and left over for 24 hrs. The extracts were later filtered using Whatman No.1 filter pape
r and the filtrates were ud afresh, some portions were kept inside the refrigerator for further usage.
Two layers of Whatman No. 1 filter papers were put in each Petri dish of 9 cm diameter and five eds of Chromolaena odoratum obtained from a farm in University of Ado-Ekiti campus were placed in each Petri dish. The Petri dishes were moistened daily with the five different filtrates using syringe and needle. The experiments were replicated ten times in each treatment of the extracts.
Control experiments were t up with Petri dishes moistened with distilled water and were replicated ten times. All the Petri dishes were put in growth chamber at room temperature. The eds were considered germinated upon radicle emergence. The germination, radicle and plumule growth elongation measurements were recorded at 24 hrs interval for six days. The results obtained from the extracts treated eds were compared, statistically using t-test analysis, to tho obtained from the control experiments.
3. Results and Discussion
The effects of the aqueous extracts derived from rice husks and sorghum stem on the germination of Chromolaena odoratum are shown in Tables 1 and 2 respectively. The extracts brought about considerable inhibition on the germination of Chromolaena odoratum eds. For example, in the rice
husk extract (Table 1), while 30% of the eds had germinated at 48 hrs experimental time in the control, no germination was obtained in all concentrations of the extract treated eds until the 72 hrs experimental time. Similarly in the sorghum extracts, 26% of the eds germinated at 48 hrs experimental time in the control experiment while only 12%, 6%, and 2% of the eds germinated at the 5 g, 10 g and 15 g extract concentrations respectively, with no germination occurring at the 20 g and 25 g extract concentrations (Table 2).
In both extracts, the degree of inhibition incread with the increa in the concentration of the extracts suggesting that the effects of the extracts were concentration dependent. Table 1 revealed that while 12% of the eds had germinated in the 5 g rice husk extract concentration in the 72 hrs experimental time, only 10%, 8%, 8%, and 6% of the eds respectively germinated in the 10 g, 15 g, 20 g and 25 g extract concentrations. Also, in the sorghum extracts (Table 2), 26% of the eds germinated at 5 g extract concentration but 10%, 8%, 6% and 4% germinated at 10 g, 15 g, 20 g and 25 g extract concentrations respectively. It was apparent from the results that the rice husk extracts had more inhibitory effects on the germination of C. odoratum as no germination was recorded until 72hrs of the experiment (Table 1).
The results of the effects of the aqueous extracts from the rice husks and sorghum stem on the radic
le lengths of Chromolaena odoratum were shown in Tables 3 and 4 respectively. The radicle lengths were retarded in all the
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Allelopathic Potentials of Some Crop Residues on the Germination and Seedling Growth of
Chromolaena Odoratum L.
222
Table 1 Effects of aqueous extracts from rice husk on the
germination of Chomoleana odoratum L. (%).
Extracts (g/200mL)
化合物的分类Experimental time (Hrs)
24 48 72 96 120 144
5 0 0 12 14 1
6 2 10 0 0 10 14 6 4 15 0 0 8 12 10 4 20 0 0 8 12 6 4 25 0 0 6 10 4 2 Control 0 30 18 8 2 2
Table 2 Effects of aqueous extracts sorghum extracts on the germination of Chromoleana odoratum L. (%).
Extracts (g/200mL)
Experimental time (Hrs)
24 48 72 96 120 144
ba
5 0 12 2
6 12 2 0 10 0 6 10 16 12 0 15 0 2 8 6 6 18 20 0 0 6 5 4 10 25 0 0 4 4 5 8 Control 0 26 16 10 6 4
extracts treated eds when their lengths were compared to tho from the control experiments. In the rice husk extract (Table 3), the radicle length in the control experiment was 0.22 cm at 144 hrs experimental time while the lengths were 0.14 cm, 0.08 cm, 0.07 cm, 0.05 cm and 0.05 cm respectively in the 5 g. 10 g, 15 g, 20 g and 25 g extract concentrations. Similar trend was obtained in the sorghum extract experiments (Table 4). Tables 3 and 4 also revealed that the degree of retard
ation in the radicle lengths incread with increa in concentration of the extracts, with the rice husk extracts demonstrating more inhibitory effects on the C. odoratum eds as no radicle growth was recorded until 96 hrs of the experiment.
The aqueous extracts also retarded plumule lengths of C. odoratum (Tables 5 and 6). No growth was recorded in both extracts until 96 hrs of the experiment. The results tend to suggest that plumule growth was more retarded by both extracts than the radicle (Tables 5 and 6). The findings corroborated the earlier asrtions of Turk et al. [5] that some plant residues demonstrated allelopathic effects by inhibiting plumule and radical lengths. However statistical analysis (P < 0.05% level) revealed that there were no significant Table 3 Effects of aqueous extracts of rice on radical length (cm) of Chromoleana odoratum L.
Extracts
(g/200mL)城市管道
Experimental time (Hrs)
24 48 72 96 120 144
5 0 0 0 0.03 0.09 0.14
10 0 0 0 0.02 0.06 0.08
15 0 0 0 0.02 0.05 0.07
20 0 0 0 0.01 0.04 0.05
25 0 0 0 0.01 0.04 0.05 Control 0 0 0.03 0.12 0.21 0.22 Table 4 Effects of aqueous extracts of sorghum extracts on radical length (cm) of Chromoleana odoratum L.
Extracts
(g/200mL)
Experimental time (Hrs)
24 48 72 96 120 144
5 0 0 0.01 0.09 0.21 0.22
10 0 0 0 0.02 0.07 0.09
15 0 0 0 0 0.02
0.03 20 0 0 0 0 0.01
0.02 25 0 0 0 0 0.01
0.02 Control 0 0 0.04 0.13 0.24 0.27 Table 5 Effects of aqueous extracts of rice on plumule length (cm) of Chromoleana odoratum.
Extracts
(g/200mL)
Experimental time (Hrs)
终生的意思24 48 72 96 120 144
沈阳婚礼
5 0 0 0 0.01 0.05 0.07
10 0 0 0 0.01 0.03 0.05
15 0 0 0 0 0.02
0.03 20 0 0 0 0 0.02
0.03 25 0 0 0 0 0.01
0.03 Control 0 0 0.01 0.07 0.14 0.15 Table 6 Effects of aqueous sorghum extracts on plumule length (cm) of Chromoleana odoratum L.
Extracts
(g/200mL)
Experimental time (Hrs)
24 48 72 96 120 144
5 0 0 0 0.0
6 0.15 0.18
10 0 0 0 0.01 0.05 0.06
15 0
0.01
0.02 20 0 0 0 0 0.01
0.01 25 0 0 0 0 0.01
0.01 Control 0 0 0 0.08 0.17 0.02 differences in the plumule and radicle lengths of the extract treated eds and tho of the control in the two different aqueous extracts ud in this study. Also there were no significant differences in the plumule and radical lengths in the varying concentrations of the two extracts.
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Allelopathic Potentials of Some Crop Residues on the Germination and Seedling Growth of
Chromolaena Odoratum L.
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4. Conclusion
Results from this study were similar to that of Jadher and Goyanar [15] who obrved that the percentage ed germination, plumule and radicle lengths of rice and cowpea were decread with increasing concentrations of Acacia auriculiformis leaf leachates and also with Quadhia [16] who obrved that extracts from C. gigantea inhibited radicle and plumule growths of Lathyrus sativa. Plant residues are now known to contain allelochemicals which are relead into the soil during decomposition. Previous study by Cherney et al. [17] found vanillic acid, p-hydroxy-benzaldehyde, p-coumaric acid and Ferullic acid in four hybrids of sorghum. Cheema [18] revealed that mature sorghum contained acids-gallic acid, caffeic acid, ferulic acid and chlorogenic acid. Two other compounds dhurin and sorgoleone were also associated with allelopathy of sorghum. Sorgoleone is a long chain hydroxyquinnine exuded from growing sorghum root. Rice allelopathy could be attributed to P-hydroxyl benzoic acid, syringic acid, vallinic, ferullic, P-coumaric and o-hydrophenyl acetic acid it contained [19]. Also Ebana et al. [20] identified ven Quantitative Trait Loci (QTLs) prent in the plant that could be associated with rice allelopathic activity. Hence the chemicals must have been responsible for the inhibition of ed germination and the retardation of edling growths of radicle and plumule of Chromolaena odoratum in this study. Further rearch activities might be required to enhance the utilization of this allelopathic feature of the plant residues in the control of this weed.
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心情愉悦的图片
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