Introduction
Parthenium hysterophorus is native of West Indies. It occurs in USA,
Mexico, Argentina, Uruguay, Trinidad, Guyana, Jamaica, South Africa, Mauritius, North
Viet-nam and India. Parthemum is an exotic weed accidentally introduced in India in 1955
through the imported food grains. At present it has occupied almost all parts of India and
is attracting the attention of all.
Parthenium belongs to Asteraceae family and normally grows to a height
of about I to 1.5m. The plant starts flowering in about a month after germination and
keeps growing throughout the year under optimum conditions. The seeds are easily carried
away by wind and is present in waste lands and crop lands. By this way it is well
established in India and at present about 2.5 to 3 million hectares of land has been
invaded by this weed. Prolific seeding habit of parthenium, non-dormancy and extreme light
weight of its seeds armed with pappus are some of the characteristics which help its
extensive spread and establishment. Parthenium produces enormous quantity of pollen which
is carried away easily and settles on vegetative parts. The pollen grains inhibit fruit
set in tomato, brinjal, beans etc. Presence of parthenium in cropped lands can cause yield
reduction upto 40 per cent.
Distribution
Parthenium is found in many parts of the country. In Tamil Nadu it is
distributed in almost all districts irrespective of the ecological differences. It is
absent only near seashore. It is prevalent in fertile lands, marshy lands, and in shady
places. It is common in vertisols than alfisols. It is also observed on the road sides and
waste lands. It can tolerate drought condition also to a certain extent. Under favourable
conditions parthenium completes about three generations in a year. It is also reported
that parthenium weed has remarkable power of regeneration. The stumps left after cutting
the plant, sprout back producing a large number of shoots from latent crown buds. Flowers
are produced on such shoots within thirty days (Dhawan and Dhawan, 1996).
Allergies
Parthenium causes severe human and animal health problems.
Sesquiterpene lactones derived from plants of the family Asteraceae are responsible for
contact dermatitis (Hosmani, 1995). The active principle is parthenin. In addition to
chemical inhibitors like caffeic acid and p-coumaric acid, it is also responsible for some
of the allelopathic effects. The plant has dense pubescent hairs which are responsible for
skin allergies. Severe cases can lead to septicaemia infection. Respiratory allergies are
also reported due to parthenium contact. Parthenium is also responsible for bitter milk
disease in livestock fed on grass mixed with parthenium.
Eradication
Pulling out the plant with root before flowering and burning is one of
the easiest way of control of parthenium. Mealy bug (Ferris virgata) can be used to
control parthenium. It feeds on the root and the affected plant starts drying due to
wilting. Another insect lantana bug (Orthezia insignis) is also effective in controlling
it. The beetle (Zygogramma bicolorata) is another important beetle to control parthenium.
It causes defoliation in the plant and finally destroys it.
A leguminous weed, Cassia sericea inhibits the growth of parthenium by
suppression,
The use of monosodium methylene arsenate (MSMA) at 4.4 kg per ha
controls the weed. Ten per cent solution of 2,4-D + 2,4,5-T (Spoulox) applied at 75
gallons per hectare gives complete kill of the weed.
Due to growing awareness about environmental pollution and herbicide
residue in soil and water, the sulphonyl urea herbicides like chlorimuron ethyl (20 kg/
ha) and metasulfuron methyl (3.5 g/ha) which are needed in very small quantities can be
used to control parthenium in non-cropped areas (Mishra and Bhan, 1994).
Cropping and competition exploits the differential growth habits,
adaptabilities and competitive abilities of crops and crop varieties to prevent, suppress
or reduce weed establishment. Growing of maize, sorghum and sunflower signijicantly
suppressed the population of parthenium (Sankaran et al., 1996). The 5 percent leaf
extract of Abutilon indicum and Tephrosia purpurea causes maximum germination inhibition
(90%) of parthenium and significantly reduces root and shoot elongation, dry matter
production and vigour index,
Hand spraying of sodium chloride at 20 per cent concentration mixed
with one ml of soap oil (Teepol) destroys parthenium to a great extent. Spread of
parthenium exclusively multiplying by seeds can be effectively contained at any of the
following two stages of its life cycle: i. seed formation stage and, ii. seed germination
stage.. The aqueous foliar extracts of Azadirachta indica, Aegle marmelos and Eucalyptus
tereticomis, which totally inhibit the seed germination of parthenium can be exploited as
an easy to obtain, cheap, effective bioherbicide for containing the spread of congress
grass (Dhawan and Dhawan, 1995).
It is also reported that leachates in various combinations of Cassia
fistula L. and Xanthium strumarium L., Awdirachta indica A. Juss and Lantana camara L. ,
Salvadora oleoides Decne and Albizzia lebbeck Benth, Prosopis juliflora (Sw) DC and Cassia
siamea Lamk. and Datura alba Nees and Acacia nilotica L., have allelopathic potential
towards parthenium (Dhawan and Gupta, 1996).
Parthenium plants are affected by two diseases in Tamil Nadu, phyllody
and powdery mildew. Phyllody affected plants show reduced growth, curved leaves and
modified floral structures. No seed setting takes place, in infected plants. Tender parts
are affected within 3-6 days.The entire plant is covered by powdery growth and later dries
completely. Seed setting is reduced by 50 per cent. The pathogen is identified as Oidium
parthenii and can not be controlled by chemical or cultural practices. Now biological
control methods are gaining recognition as they are specific and not harmful to the
eco-system (Doraiswamy and Manickarn, 1996).
Potential uses
Instead of eradication of parthenium constituents of parthenium can be
made use of for our purpose. Information is available on the possibility of utilization of
parthenium as a green leaf manure, as a biopesticide and also as a compost for crop
plants.
Green manure value
For the main crop of rice, the effect of parthenium green leaf manure
on plant height was comparatively less as compared to other green manures like leucaena
and sunnhemp. Whereas, in the ratoon rice crop parthenium green leaf manure was superior
in influencing the plant height (Sudhakar, 1984). Similarly in the main crop, parthenium
green leaf manure produced less number of filled grains while it produced the highest
number of filled grains in the ratoon crop. Among the green leaf manures tried, the
residual effect for dry matter production was the highest with parthenium as green leaf
manure. In the ratoon crop, parthenium recorded the highest grain yield at 100 Kg N per ha
level.
Compost
To assess the manurial value of parthenium and its composting value, a
composting experiment was conducted and compared with other organic wastes (Son, 1995).
The organic wastes tried were coir pith, lpomoea, water hyacinth, parthenium, paddy straw
and sugarcane trash. Composite culture consisting of Pleurotus sojarcaju and Trichoderma
viride were used as inoculants for hastening the process of composting,
The wastes were chopped into bits of about 10cm length. One layer of
the waste was spread above which the inoculum was spread. Another layer of waste was
spread above which one kg of urea was spread. The organic waste was spread and the process
of layering was repeated till a minimum of I m height was reached. Water was sprinkled in
the stacking process to maintain 60 per cent moisture. The heaps were kept under
semiaerobic condition and covered with red earth at the top. After one month, a turning
was given and the moisture content maintained. In about 45 to 50 days, a good quality
compost was obtained.
Wide variation in the nutrient content of the organic wastes was
noticed. The total N content was in the order of parthenium > lpomoea > water
hyacinth > sugarcane trash > paddy straw > coir pith whereas the total P was in
the order of lpomoea > parthenium > water hyacinth > sugarcane trash > paddy
straW > coir pith. The total K was in the order of paddy straw > coir pith >
sugarcane trash > parthenium > water hyacinth > lpomoea. The total K content in
paddy straw, coir pith and sugarcane trash could be a potential source for contributing K
to the soil. Regarding the biochemical parameters, parthenium and coir pith recorded the
highest phenol content.
The organic carbon content varied among the wastes. The decomposition
of organic carbon was greatly influenced by microbial inoculants.
In general, all the inoculants reduced the organic carbon content of
the wastes during decomposition and the reduction was to the tune of 36.23, 28.38, 21.23,
17.99, 25.18 and 25.96 per cent over control for coir pith, lpomoea, water hyacinth,
parthenium, paddy straw and sugarcane trash, respectively. This could be attributed to the
role of microbial activity due to the addition of inducers to the wastes for composting
(Nagarajan et al., 1985). The increase in N content was 4.02, 1.78, 1.60, 1.70, 2.86 and
3.29 folds over control for coir pith, lpomoea, water hyacinth, parthenium, paddy straw
and sugarcane trash, respectively. The increase in the total N content of wastes was due
to the decomposition of the carbon and thereby increasing the inorganic elements
(Rajendran,1991).
The C:N ratio was markedly reduced by the inoculants in all the organic
wastes. Among the organic wastes, coir pith recorded the highest reduction in C:N ratio
followed by sugarcane trash, paddy straw, lpomoea, water hyacinth and parthenium. The
reduction in C:N ratio was the result of decrease in carbon content which was utilized as
the energy source for the soil microflora and consequently converted into the N content.
Similar results were reported by Nagarajan et al. (1985), Rajendran (1991) and
Thilagavathi (1992). Parthenium compost recorded higher P content while sugarcane trash
compost recorded higher K. content. The phenol contents varied from waste to waste
compared to the initial values on 42nd day of composting. The reduction in phenol content
was substantial in all wastes. The highest percentage of reduction in phenol content
(41.4%) was observed with parthenium eventhough the phenol content was higher in
parthenium at the end of composting.
Response of crops to parthenium compost
Field experiments were conducted with rice followed by soybean and
maize followed by cowpea using the composts prepared out of different organic wastes. All
the organic waste composts including parthenium enhanced the organic carbon status of the
soil indicating beneficial effect of incorporation of wastes. The highest increase was to
the extent of 22.6 and 20.8 per cent over NPK alone due to application of composted
parthenium at flowering and harvest stages, respectively. Among the treatments, parthenium
compost recorded higher available soil N at post harvest stage. This could be attributed
to. the higher N content of parthenium compost than other composts from organic wastes.
All the organic waste composts recorded higher grain yield of rice as
main crop over NPK alone. Similarly, all the organic waste composts recorded higher grain
yield of maize as main crop over NPK alone.
In the case of residual crops of soybean after rice and cowpea after
maize, the parthenium compost application to the main crops recorded the highest yield of
1917 Kg per ha and 1285 Kg per ha, respectively as compared to other organic waste
composts and application of NPK alone. This residual effect of parthenium can be exploited
for beneficial use.
Biocontrol value
The weed population in rice field was found to be influenced by the
incorporation of composted organic wastes. Among the treatments the composted coir pith
and parthenium recorded lower weed population. The application of organic waste composts
reduced the weed count from 30.5 to 39.8 per cent over NPK at 60 DAT. This could be
attributed to the role of allelopathic compounds such as phenol present in these two plant
debris even after composting (Son, 1995). Similar reduction in weed population due to
parthenium as green leaf manure for rice was reported earlier by Sudhakar (1984). Among
the different composts, coir pith and parthenium compost recorded lower weed population in
maize.
The beneficial effect of organic wastes in reducing the incidence of
pests such as stem borer and leaf roller was observed due to the application of organic
waste composts. Generally under incorporation of organic wastes, the reduction in pest
incidence was to the extent of 43.4 to 50 per cent at 60 DAT as compared to NPK alone
(Son, 1995). Incidence of leaf roller in rice crop was the highest with urea application,
whereas it was the lowest with parthenium as green leaf manure application (Sudhakar,
1984). This biocontrol behaviour of parthenium can be exploited.
Thirteen fungal species such as Aspergillus Candidas, A. flavus, A.
fumigatus, A. glaucus, A. niger, Altemaria alternata, Curularia pallescens, C. lunata,
Fusarium equiseti, F. oxysporum, Penicillum notatum, Rlzizapus arrhims and Trichoderma
ignorum were isolated from the phyllosphere of young, mature and senescent but healthy
leaves of parthenium. The total population of microrganisms showed considerable increase
from young to mature to senescent but healthy leaves (Dhawan and Dhawan, 1995).
However, if some strain of any of these fungi are developed which meet
the requirements of using them as biocontrol agents i.e. host specificity and strong
virulence, only then they can be considered as potential bioherbicides for biocontrol of
parthenium (Dhawan and Gupta, 1996).
Soil amendment value
Any organic waste application aids in moisture conservation which is
utilised for better root penetration and crop growth. In general, incorporation of organic
wastes enhanced the moisture content of the soil to the tune of 45.5 to 77.4 per cent as
compared to application of NPK alone to maize crop (Son, 1995). This enhancement could be
attributed to the higher water holding capacity of the soil due to the influence of
organic waste application. The moisture in soil due to application of parthenium compost
was 14.5 and 16.5 per cent at 0-15 and 15-30 cm depths as compared to 10.7 and 11.6 per
cent at 0-15 and 15-30 cm depths of soil due to application of NPK alone. This may be due
to building up of organic carbon status in soil. This behaviour can be well utilised for
moisture conservation practices. Allelopathic effect Allelopathy is an expression of a
general phenomenon of chemical interaction and are known to inhibit seed germination by
inhibiting hydrolysation of reserve food, cell division and several other factors (Rice,
1974). An experiment conducted on allelopathic effect of parthenium leaf extract on
sunflower and sorghum revealed that the germination percentage, shoot and root length, dry
weight and vigour index decreased with an increase in the concentration of parthenium leaf
extract from one to 10 per cent (Murthy et al. ,1995).
References
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(Source : Ramaswami, P.P. (1997). In : Proc. First International
Conference on Parthenium Management (Vol. I) : 77-80) |