Tithonia diversifolia (Hemsl.) A.

Gray, commonly known as Mexican sunflower, is a plant

that produces volatile oil largely spread around the world. This species is a perennial
herb from

the family Asteraceae, tribe Heliantheae, native from both Mexico and Central America,
and it

can be encountered mainly in the both tropical and sub-tropical areas of Americas,
Africa and

Asia ( "Tithonia diversifolia". Germplasm Resources Information Network. Agricultural

Service, United States Department of Agriculture. Retrieved 2011-05-19.

USDA, NRCS (n.d.). "Tithonia diversifolia". The PLANTS Database (plants.usda.gov).

North Carolina: National Plant Data Team. Retrieved 11 December 2015.).

T. diversifolia is described as an invasive weed in different ecosystems, mainly in Africa

China ( Muoghalu, 2015), which is related to problems of

ecological imbalance in areas infested with this plant because it is able to adapt to
different

climate and soil conditions ( Muoghalu, 2015).

The chemical constituents of T. diversifolia are well known and many of its secondary

metabolites are described in literature. Most of the compounds isolated from T.

extracts belong to the classes of the sesquiterpene lactones, flavonoids and

derivatives (M. Kuroda, A. Yokosuka, R. Kobayashi, M. Jitsuno, H. Kando, K. Nosaka, H.

Yamori, Y. Mimaki Sesquiterpenoids and flavonoids from the aerial parts of Tithonia
diversifolia
and their cytotoxic activity Chem. Pharm. Bull., 55 (2007), pp. 1240-1244G. Zhao, X. Li,
W.

Chen, Z. Xi, L. SunThree new sesquiterpenes from Tithonia diversifolia and their anti-

hyperglycemic activity Fitoterapia, 83 (2012), pp. 1590-1597). A recent publication by

research group describes the relationship between the LC–MS-based metabolic profile
of T.

diversifolia and some abiotic environmental factors (soil nutrients and climate factors)
for

individuals grown in two distinct regions of Brazil during a period of 24 months. The
results

demonstrate a clear and direct influence of the environmental conditions on the

and accumulation of some classes of non-volatile secondary metabolites, especially

and phenolics, in four different plant tissues (leaves, stems, roots and inflorescences)
(Effect of

the environment on the secondary metabolic profile of Tithonia diversifolia: a model for

environmental metabolomics of plantsBruno Leite Sampaio, RuAngelie Edrada-Ebel &

Batista Da Costa Scientific Reports volume 6, Article number: 29265 (2016) ).

T. diversifolia plant species has been associated with ecological imbalance.

Due to its high adaptability to different environmental conditions (climate and soil),

high dispersion and rapid growth rate, T. diversifolia has an advantage to occupy

degraded areas and dominate over native species. The impact of both species on the
diversity

and floristic compositions of native species was evaluated. Relative to the uninvaded
(control)

plots, the average number of plant species in Chromolaena and Tithonia invaded plots
was

reduced by 31.6 % and 25.4 % respectively; Shannon-Wiener diversity was reduced by

27 % respectively; species evenness was reduced by 10.5 % and 24.9 % respectively.

similarity of index between invaded and uninvaded plots for Chromolaena and Tithonia
were

43.8 % and 32.6 % respectively. The number of native species was greatly reduced in
areas

invaded by C. odorata than in T. diversifolia invaded areas, leading to reduced species

and evenness. Reproductive parameters including mean number of flowers per plant,
mean

number of fruits per plant, mean number of seeds per fruit, mean weight of seeds and
mean

weight of each seed of the native species in the uninvaded plots were higher than those
of the

invaded plots for Tithonia diversifolia and Chromolaena odorata. The height of all
native

species in the uninvaded plots were taller than those of the invaded plots for T.
diversifolia and

C. odorata. It was concluded that invasion by C. odorata and T. diversifolia greatly

diversity of the native plant species with a corresponding reduction in their growth and

reproductive parameters.

217 FUTA Journal of Research in Sciences, 2015 (2): 217-230 CHANGES IN SPECIES
DIVERSITY,

COMPOSITION, GROWTH AND REPRODUCTIVE PARAMETERS OF NATIVE VEGETATION

BY CHROMOLAENA ODORATA AND TITHONIA DIVERSIFOLIA IN OSUN STATE,

T. diversifolia exhibits allelopathic properties having water soluble

allelochemicals in its plant parts and a phytotoxic potency capable of suppressingcrop

plant development and nutrient accumulation

Laboratory and soil cultured experiments were conducted to evaluate: the allelopathic
activities

of the fresh shoot aqueous extracts of Tithonia diversifolia (FSET) and Chromolaena
odorata

(FSEC) at concentrations 50%, 80% and 100% on the germination, radicle and plumule
growth

of Hibiscus sabdariffa plants, investigate the effects of 100%FSET and100%FSEC on the

chlorophyll pigments, ascorbic acid and protein contents of this plant.

Seed germination and juvenile seedling growth were reduced with the lowest
concentration of

the different extracts. The radicle growth was moreinhibited than the plumule growth.
The

plant extracts had a concentration-dependent reduction of the seedling growth of the

crop. The FSET was more phytotoxic than FSEC. The soil-cultured experiment showed
that both

FSET and FSEC significantly enhanced the number of leaves, chlorophyll b, total
chlorophyll,

ascorbic acid and protein contents of older H. sabdariffa plants. In addition to these,
FSEC

significantly promoted the shoot height, stem girth, leaf area, leaf area ratio and shoot
fresh

and dry weights of these plants. This study has shown that FSET and FSEC could play

differingallelopathic physiological role, depending on the medium of growth and age of

target plant. It was noted that the phytotoxicity of C. odorata and T. diversifolia got
degraded

in the soil such that the extracts were stimulatory to the growthof the target plants. This

finding suggested that C. odorata could serve as green manure or bio- fertilizer to boost
the

growthand productivity of established H. sabdariffa plant on the field.

ALLELOPATHIC EFFECT OF TITHONIA DIVERSIFOLIA AND CHROMOLAENA ODORATA ON

GERMINATION, GROWTH AND CHLOROPHYLL ACCUMULATION OF HIBISCUS SABDARIFFA

)O. O. OTUSANYA, A. A. OGUNWOLE & M. O. TIJANI

T. diversifolia works as green manure, increasing crop productivity, and acts as fodder for

domestic animals because of its high mineral and nutrient values.

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native

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allelopathic and contains several phytotoxic substances, such as sesquiterpene

lactones . The evidence also suggests that some of the phytotoxic substances in T.

diversifolia are probably released into the soil through the decomposition of the plant
residues
and the exudation from living plant tissues of T. diversifolia, which act as allelopathic

substances. The allelopathic substances can inhibit the germination and growth of
neighboring

plants

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Therefore, the allelopathic substances released from T. diversifolia may

provide the plants with a competitive advantage against native plants, and may
contribute to

the plants establishing their habitats as invasive plant species. Allelopathy of T.

be involved in the invasive potential of T. diversifolia.

A study carried out from September, 2015 to May,2016 revealed that soil pH, organic
carbon
and or-ganic matter was higher in invaded site of Tithonia diversifolia than the non-
invaded site.

The diversityof plant species in the invaded site was quite lowerthan the non-invaded
site.

Tithonia diversifolia hasbecome a very strong invader in Nagaland and ithas increased its

density and abundance in the in-vaded habitats as a result posing a threat to the ex-
tinction of

native species which also include somemedicinally important species. The invasion of T

diversifolia also alters the physico-chemical proper-ties of soils in the invaded areas. The
soils in

the in-vaded areas become more nutrient rich. It was clearfrom the results that the
values of all

soil organiccarbon content were found to be higher in the Titho-nia invaded areas as
compared

to the non invadedarea. Minimum change was observed in the case o pH as compared
to other

parameters. A high level oforganic matter in the soil indicates reduced bulkdensity i.e.
improved

soil structure, aeration andhigh water holding capacity which attribute to richproductive

capacity of the soil. Hence T. diversifoliawith its high nutrient status by the presence of

highorganic matter and carbon is a potential soil im-prover for enhanced productivity
and can

be recom-mended for use as fallow plants for enhancing pro-ductivity or as major

of compost manurewith proper management practices to control thespreading of plant

scale.

Variation of soil pH, moisture, organic carbon and organic matter content in the invaded
and

noninvaded areas of Tithonia diversifolia (Hemsl.) A. gray found in Nagaland, North-east

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