WEED FLORA AND WEED DISTRIBUTION IN RICE

ECOSYSTEM

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Transplanted rice

It is the traditional method of cultivating rice is flooding condition

in which the young seedlings are transplanted from the nursery.

The predominant weed in the transplanted rice field

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Cynodon dactylon, Echinochloa colonum, Dactyloctenium aegyptium and Chloris

barbata among the grasses and among the dicot weeds, Alternanthra pungens,

Portulaca oleraceae, Eclipta alba and Tridax procumbens were the predominant

broad leaved weeds.

Echinochloa colona (L.) Link.

It is annual grass grows commonly in waterlogged conditions belonging to the family Gramineae. It is also called as jungle rice and in tamil it is called as varnampul.

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It grows up to a height of 60 cm. Leaf-blade 7.5 to 15 cm long, often

blotched with purple or almost black cross bands ligule 0,2-5(9) cm.

Inflorescence linear. Spiklelets ovoid-ellipsoid, to 2mm with fruit caryopsis.

It is propagated by means of seeds. It is an excellent fodder

Echinochloa crus-galli (L.) Beauv.

It is an annual grass belonging to the family

Gramineae. It is a mimic of rice. It grows upto 37cm

height with no ligule.Inflorescence an erect panicle

with fruit ovate a elliptic grain.

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It propagate by means of seeds.

Eclipta prostrata L. (Syn. Eclipta alba Hassk.)

It is an annual broad leaved weed also called as Karasaranganm in

the family Asteraceae. It is diffusely branched stem is round and

fleshy with strigose hairs. Leaves opposite, sessile, linear and

strigose. Flower head is small, axillary and terminal. Fruit is

Achenes. Propagate by means of seeds.

 

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Fimbristylis milliacea (L.) Vahl.

Belongs to Cyperaceae family. It is erect annual sedge, with

stem caespitoe to 30 cm ligule absent. Inflorescence is

compound and the fruit is nut obovoid.

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Propagation by means of seed. It is common in wet land ecosystem

Marsilea quadrifolia L. (Pteridophyta)

The water fern belongs to the family Marsileaseae also called as Arai keerai in Tamil. It is an Amphibious herb with procumbent rhizomes. Occurs in marshy areas, also in rice fields and floating in running water. The stem is long creeping stolon, rooting at the nodes. Leaves are erect on long petioles. Leaflets are 4, rather large, obovate and entire on the margin.

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Veins are many and forking. Propagate by means of Stolons and spores

Cynodon dactylon Pers.

In black soils and in dryland is a noxious weed and once a field is infested with it, cultivation becomes impossible. It is considered as one of the ten worst weeds in the world and problematic in all tropical and subtropical areas in dry land and garden lands.

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It belongs to the family Graminae (Poaceae) and common name is

Bahama Grass, Hariyali. In tamil it is called as Arugampullu.

A perennial grass extensively creeping by means of scaly rhizomes or by strong flat stolons, very common in plains and hills sler and grows upto 7.5 to 30 cm height.

The underground stems are hard, brittle, thick, pale white in colour and covered with short scale-leaves and occur at varying depth in soil. Leaves are linear, finely acute, 7.5 to 12.5 cm long, spikes 3 to 6. Spikelets are light green or purplish, sessile, laterally compressed, alternately 2-seriate, imbricate and 1-flowered.

Grain is minute, oblong somewhat flattened, rounded on black. Propagated by through seeds and underground stolons.

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Chloris inflata Link (Syn. Chloris barbata Sw.)

Chloris barbata belongs to the family Poaceae and also called as Mayil

kondai pul. It is a tufed. A tufted perennial, commonly found as a

weed in dry cultivated fields.

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Culms upto 60 cm high. Leaves of 7.5 to 12.5 cm long.

Inflorescence with 6 to 15 digitately arranged spikes, spikelets are

usually purplish in colour.

Fruit is caryopsis. Propagation by seeds. It is a good fodder

grass

Dactyloctenium aegyptium (L.) P. Beauv .

Dactyloctenium aegyptium (L.) P. Beauv . is buffalo grass in the

family Poaceae. It is also called as Kakkakalpal in Tamil. It is an

annual, grass growing in waste places and dry cultivated lands.

Stem is Culms 10-62.5 cm high.

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Leaves flat, 5 to 20 cm long, glabrous. Fruit is Caryopsis.

Propagation by seeds. Cattle graze this readily

Portulaca oleracea L.

It is a succulent broad leaved weed and it belongs to the family

Portulacaceae. Common name is Indian Purslane. In tamil it is

called as Paruppu Keerai.

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The main stem is short and erect bearing a number of

lateral branches which lie prostrate on the ground,

they grow to a length of 4-20 inches and are green or

reddish in colour

The leaf-stalk is short. Flowers are without stalks, from 2-6 in number and are collected together in clusters at the s of branches. Sepals are 2 and fleshy; they are united at the base and are free above.

Petals are 5 and are yellow in colour. Fruit is dry, dehiscing transversely by the upper part enclosed by the sepals, coming off as a lid leaving the lower part in the plant.

Seeds are minute, blackish brown in colour and are covered with concentric lines of tubercles. Propagation is by seed.

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Alternathera pungens H.B. & K., (Syn. Alternanthera echinata S.)

An introduced weed from tropical America, now common in dry land, waste lands and roadsides.

The plant is gregarious in habit and produces roots at the nodes for vegetative propagation.

Alternathera pungens Broad leaved weed is also called as Khaki Weed and Mull ponnanganny in

Tamil.

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It belongs to the family Amaranthaceae. It is a biennial wed with

trailing, diffusely branched habit. The stem is round, hairy, slightly

tinged with pink the character of leaf is opposite, elliptic, obtuse

and flowers in auxiliary spikes and small with fruit Achene.

Propagation by means of seeds.

Trianthema protulacastrum. L.

Trianthema protulacastrum.L. is annual prostrate herb belongs to the

family Aizoceae. In tamil it is called as Saranai. Stem is round, striate,

glabrous below and hairy. Leaves are oppositve, petioled, petiole

sheathing at the base, obovate, in unequal pairs.

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Flowers is solitary and sessile. Fruit is capsule. Propagation by

means of seeds and cuttings. It grows gregariously grows causing

considerable hinderance to normal cultivation.

Cleome chelidonii L. f.

Cleome chelidonii is the broad leaved weed belongs to the

family Capparaceae. It is a erect glabrous much annual herb

growing to a height of 30-60 cm.

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Stem is covered with pointed hairs, leaf have long

pertioled, digitately compound, flower is pink, bracteates

with small bracts with capsule fruit and propagate by

seeds

Parthenium hysterophorus L.

Parthenium hysterophorus L. is the generally found in non-cropped situation but now a days a weed of cropped field. It

belongs to the family Compositeae and commonly called as congress weed and visha poondu in Tamil.

 

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It is a annual herb grows upto a height of 1.5 m.

Stem is slunder with hairs, leaves are alternate and

sessile flower is white in colour with heads many.

Fruit is called as achene. Propagated through seeds.

 

Ammannia baccifera (L.) m.

Is an erect annual broad leaved herb growing upto a height of 30 cm. It is

Lythraceae family commonly called as Blistering Ammania and in tamil

called as Neermael neruppu. Stem is tetragonus, branches at the base are

long becoming shorter towards the top.

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Leaves are small lanceolate, sessile and opposite. Flowers are axillary

cluster; calyx tubular. Fruit is a capsule and propagate by seeds.

Direct seeded rice

Direct Seeded Rice (DSR) in place of the traditional transplanted rice

is a way to drastically reduce labor charges for nursery raising,

puddling and transplanting.

The predominant graminaceous weeds were Echinocloa crusgalli and

Panicum sp. and weed species belonging to family cyperaceae viz.,

Cyperus difformis and Cyperus iria. The broadleaved weeds included

Ammania baccifera, Eclipta alba, Monochoria vaginalis and Marsilia

quadrifoliata.

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Panicum repens L.

Panicum repens commonly called as Ginger Grass and Inji pillu in tamil. It is a

perennial grass, survive well under moist condition. Stem is Culms creeping at

the base, rhizomatous, 60 to 150 cm long. Underground stems are thick and hard,

very much resembling ginger. 

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Aerial branches are covered with pointed scale leaves at the base.

Inflorescence is much branched terminal panicle 3-5 inches long. Spikelets is

ovoid and pointed on a short stalk and has four glumes.

Propagation by underground stems and grains. It is much relished by

cattle.

Cyperus difformis L. A common weed in paddy fields Cyperus difformis is also called as Vatta

Korai. Belongs to family Cyperaceae.

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A very common sler, weak plant found in marshes and in shallow ponds;

stems tufted, 12.5 to 37.5 cm long. Stem 8-40 cm height. Leaves flaccid,

as long as the stem; bracts 2-3, 5 to 20 cm long. Spikelets many, densely

grouped into congested globose heads; glumes obovate, apex rounded.

Propagation by seeds.

Cyperus iria L.

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Cyperus iria L. belongs to the family Cyperaceae and its tamil name is

Oosikorai. It is widely distriubtued species an all marshy situations and also

occurs as a very common weed in paddy fields and in shallow ponds.

Belongs to the family Cyperaceae and its tamil name is Oosikorai

It is erect glabrous annual.

Stem is 15 to 50 cm high, trigonous. Leaves up to 42.5 cm

long; bracts 3-5, 5 to 25 cm long. Spike consists of 5-15

spikelets; spikelets linear, oblong, yellow or pale-brown and

glumes plicate.Propogation by means of seeds.

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Monochoria vaginalis (Burm. f.)

Monochoria vaginalis is a common wet land and broad

leaved weed. It belongs to family Pontederiaceae.

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A rooted aquatic herb, commonly growing in fresh water and

marshy areas. Root-stock short and suberect. Flowers in

racemes, usually blue spotted with red and petaloid.

Fruit is a capsule. Propagation by seed and also by

root-stock

Aerobic rice

Aerobic rice is a renewed way of growing rice in non-submerged

unpuddled condition in aerated soils. Aerobic rice varieties developed for

the purpose yield as much as irrigated puddled rice varieties traditionally

grown in rice paddies.

The predominant weed flora found were Cynodon dactylon, Echinochloa

colonum, Dactyloctenium aegyptium and Chloris barbata among the

grasses and among the dicot weeds, Alternanthra pungens, Portulaca

oleraceae, Cleome chelidoni, Parthenium hysterophorus, Eclipta alba and

Tridax procumbens were the predominant broad leaved weeds.

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Semidry rice

Semidry rice cultivation is growing rice under rainfed

condition and later turning to lowland crop when rainwater is

available from the tanks and/or from similar sources.

The predominant weeds were

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Cynodon dactylon and Echinochloa colona among grasses, Trianthema portulacastrum and Portulaca oleracea among

broadleaved weeds and Cyperus rotundus in sedges.

Gupta, O.P. 1998. Weed management - Principles and Practices. Agro Botanical Publishers, Bikaner.

Rao, V.S.1994. Principles of Weed Science. Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi.

Subramanian, S., A.Mohamed Ali and R.Jayakumar. 1997. All about weed control. Kalyani Publishers, New Delhi.

C. Chinnusamy, N.K. Prabhakaran P. Janaki K. Govindarajan. 2009. Compium on Weed Science Research in Tamil Nadu (25 years). AICPR-WC, Department of Agronomy, TNAU, Coimbatore - 641 003

K. A.A. Kabeer and V.J. Nair. 2009. Flora of Tamil Nadu- Grasses. Botanical Survey of India, Kolkatta.

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1. ------------ is the predominant weed in the rice field Ans: Cynodon dactylon2. Echinochloa crus-galli propagated by ---------- Ans : seed3. ----------- is the predominant weed in the direct seeded

rice field. Ans : Echinocloa crusgalli 4. Ginger Grass scientifically known as --------------- Ans : Panicum repens

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