Transcript 1.weed flora and weed distribution in rice

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
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.
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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.
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
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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.
It propagate by means of seeds.
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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.
Propagation by means of seed.
It is common in wet land ecosystem
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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.
Veins are many and forking. Propagate by means of Stolons
and spores
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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.
It belongs to the family Graminae (Poaceae) and common
name is Bahama Grass, Hariyali. In tamil it is called as
Arugampullu.
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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.
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
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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.
Leaves flat, 5 to 20 cm long, glabrous. Fruit is
Caryopsis. Propagation by seeds. Cattle graze this
readily
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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.
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 color
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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 color. 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 color 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.
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.
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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.
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.
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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.
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
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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.
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.
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Ammannia baccifera (L.) m.
It Is an erect annual broad leaved herb growing up to 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.
Leaves are small lanceolate, sessile and opposite.
Flowers are axillary cluster; calyx tubular
Fruit is a capsule and propagate by seeds.
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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.
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.
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Cyperus difformis L.
A common weed in paddy fields Cyperus
difformis is also called as Vatta Korai
Belongs to family Cyperaceae.
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.
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Cyperus iria L.
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.
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
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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
Cynodon dactylon and Echinochloa colona among
grasses, Trianthema portulacastrum and Portulaca
oleracea among broadleaved weeds and Cyperus
rotundus in sedges.
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