INTRODUCTION:

Euphorbia heterophylla (Wild poinsettia) has been reported to be widely spread as an important weed in at least 28 tropical countries and is present in 37 more (Wilson, 1981). Euphorbia heterophylla has been reported to be a serious weed of many Agricultural plants especially in the United States and Brazil where it is a major weed in Soya bean. In Brazil, it is a major weed mainly in soyabean fields (Cerdeira et al., 1981; Lorenzi, 1982; Santos and Corso, 1986). In the United States, Euphorbia heterophylla has been recognized as a major weed in Soyabean in Loiusiana (Bannon et al., 1978; Moore et al., 1990; Bridges, et al., 1992; Willard and Griffin, 1993; Berecke, 1995). It is also a weed of major economic importance in peanut and cotton in Georgia and Florida (Bridges et al., 1992).

In Nigeria, Tithonia diversifolia is a fast growing water loving annual weed that becomes woody at maturity. This fast growing habit puts it at an advantage over most other weeds which are eventually overpowered by Tithonia diversifolia when growing together. Due to this property, the weed is being considered potentially useful for fallow land management (Liasu and Alayese, 1999). Extracts from Tithonia diversifolia plant parts have been reported to contain chemicals that inhibit plant growth (Baruah et al, 1994; Tongman et al 1997).

Research on Euphorbia heterophylla has been mainly directed towards finding suitable methods for its control (Gusman et al., 1990; Moore, et al., 1990; Willard and Griffin, 1993; O’Makinwa and Akinyemiju, 1993; Brecke and Tobola, 1996). The weed has persisted as an Agricultural problem probably resulting from widespread adoption of Chemical weed control, coupled with the weed’s resistance to most herbicides; high seed production and the fact that seed germination can occur at any time throughout the growing season (Egunjobi and Kupoluyi, 1973; Wilson, 1981.

The present work was therefore designed to investigate the effect of fresh shoot aqueous extract of Tithonia diversifolia on the germination and seedling growth of Euphorbia heterophylla.

MATERIALS AND METHOD:

The experiment was carried out in the green house of the Department of plant Science of Ekiti State University, Ado Ekiti of Nigeria. Matured seeds of E. heterophylla as well as fresh shoots of T. diversifolia were collected from within the University community. Collected fresh shoot of T. diversifolia were blended using pestle and mortar. The ground plant material was weighed separately into 5g, 10g, 15g and 20g and each soaked in 100ml of distilled water for 24 hours and the filtered. The filtrate served as the fresh shoot aqueous extract (FSE).

Twenty seeds of E. heterophylla were placed in each Petri dishes double laid with Whatman No1 filter paper. 5ml of FSE from the weighed 5, 10, 15 and 20g T. diversifolia were used to moisten the double laid filter paper where the seeds of E. heterophylla were sowed. A control experiment were distilled water was used was also set up. The experiment was replicated 5times. The seeds were observed daily for germination. Opening of the seed with radicle appearance served as criterion for germination. All data collected were statistically using the analysis of variance and means separated using the Duncan’s multiple range tests.

RESULTS:

The effects of fresh shoot aqueous extract of T. diversifolia on the germination percentage and speed of germination is presented in table 1. The highest germination percentage was observed in the control experiment while the least was recorded in the 20g/100ml concentration of FSE T. diversifolia. The result showed that the higher the concentration of FSE of T. diversifolia, the lower the germination percentage of E. heterophylla. The highest speed of germination was also recorded in the seeds of E. heterophylla moistened with distilled water while the speed was slowest in the 20g/100ml concentration in both trials. The speed of germination was identical for the 5, 10 and 15g/100ml and 5 and 10g/100ml concentrations of FSE of T. diversifolia in 2011 and 2012 respectively.

Table 2 shows the effect of fresh shoot aqueous extract of T. diversifolia on the radicle and plumule length of E. heterophylla. The highest radicle length was recorded in the control experiment while the least was recorded in the seedling of E. heterophylla treated with 20g/100ml of fresh aqueous extract of T. diversifolia. The radicle lengths observed in the 10, 15 and 20g/100ml were not significantly different but lower than those obtained from the 5g/100ml FSE. The plumule length of E. heterophylla in 15g and 20g FSE of T. diversifolia were not significantly different but were the least of all the treatments. The 5g and 10g/100ml concentrations also produced identical E. heterophylla plumule lengths which were significantly lower than the control experiment.

Table1: Effects of fresh shoot aqueous extract of T. diversifolia on the percent germination and speed of germination of E. heterophylla

Treatments	Germination percentage		Speed of germination
Treatments	2011	2012	2011	2012
0g	92.5a	97.5a	69.2a	81.8a
5g	64.0b	60.0b	29.6b	44.9b
10g	45.5c	42.5c	27.8b	36.1bc
15g	30.0d	36.0cd	27.0bc	31.3cd
20g	27.5d	30.0d	21.3c	22.6d

Means with the same letter(s) within columns are not significantly different (P=0.05) according to the Duncan’s multiple range test.

Seedlings survivals of E. heterophylla were consistently lowest in the 20g/100ml T. diversifolia FSE and highest in the control experiments. The result showed that the higher the concentration of the T. diversifolia FSE, the lower the survival rate of E. heterophylla (Table3). The number of secondary roots was highest in the 5g/100ml FSE of T. diversifolia in both trials. The control experiments and the 15g and 20g FSE were not significantly different in 2011. Only the control experiment and 15g FSE gave identical numbers of secondary roots in 2012.

Table2: Effects of fresh shoot aqueous extract of T. diversifolia on the radicle length and plumule length of E. heterophylla

Treatments	Radicle length(cm)		Plumule length
Treatments	2011	2012	2011	2012
0g	27.6a	28.4a	26.9a	24.5a
5g	14.45b	15.55b	13.3b	14.4b
10g	3.55c	4.56c	8.6bc	9.6b
15g	3.43c	2.64c	8.4bc	7.7bc
20g	2.83c	1.75c	7.3c	5.8c

Means with the same letter(s) within columns are not significantly different (P=0.05) according to the Duncan’s multiple range test.

Table3: Effects of fresh shoot aqueous extract of T. diversifolia on the percent seedling survival and number of secondary roots of E. heterophylla

Treatments	Seedlings survival (%)		Number of secondary roots
Treatments	2011	2012	2011	2012
0g	98.0a	95.5a	4.7c	5.2b
5g	81.5b	78.0b	7.7a	7.5a
10g	23.3c	18.4c	6.0b	6.7a
15g	15.1c	13.3cd	4.3c	4.6bc
20g	13.3c	10.1d	3.3c	3.8c

Means with the same letter(s) within columns are not significantly different (P=0.05) according to the Duncan’s multiple range test.

DISCUSSION:

The effectiveness of fresh shoot aqueous extract of T. diversifolia in the inhibition of germination, speed of germination, as well as retardation of radicle and plumule growth of E. heterophylla had been demonstrated in this study. Otusanya et al (2007) have reported similar inhibitory effect of shoot extracts of T. diversifolia on the germination and growth of Amaranthus cruentus. Similarly, reports have shown that Chromolaena odorata used as fallow species by old farmers in the Nkometon III area of southern Cameron was able to suppress the growth of Imperata cylindrica which used to be a problem in that area (IITA, 1995). The findings from the present work could be attributed to the suppressing ability of Tithonia diversifolia on E. heterophylla in the study area. This study could also give an insight to the herbicidal property of T. diversifolia on E. heterophylla.

It is concluded that in addition to the ability of T. diversifolia to increase the performance of some crop plants as reported by Ademiluyi and Omotoso, 2007; Ademiluyi 2012, it could also serve as bio-herbicide to suppress the growth of E. heterophylla as evident in the result of this work.

REFERENCES:

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2. Ademiluyi, B.O. 2012 Effect of Tithonia diversifolia (Hemls) A. Gray on the growth and yield of okra (Abelmuscus esculentus) Journal of Agricultural Science and Technology B 2, 219-222,

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17. Santos, D.M. and Corso, G.M. (1986). Germinacao, pre-plantio, pre-emergencia e pos-emergencia de Euphorbia heterophylla L. (amendoimbravo) sob a influencia do Diuron. In: Congresso Da Sociedade Botanica de sao Paulo, 6, Campinas, Anais, 59-65.

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20. Wilson, A.K. (1981). Euphorbia heterophylla: A review of distribution, importance and control. Tropical pest management, 27:32-38.

Received on 13.12.2012 Accepted on 28.12.2012

Int. J. Tech. 2(2): July-Dec. 2012; Page 62-64