These recommendations are for medium altitude (700-1500 m)
areas that include Wangdue, Punakha, parts of Trashigang-Monggar
in the dry zone and Tsirang, Dagana, parts of Sarpang, Samtse,
Samdrup Jonkhar in the humid zone.
VARIETIES
IR 64
• High yielding tropical semi-dwarf variety
• Matures 145-150 days after sowing.
• Grain quality similar to local white rice
• Milling recovery 65%.
• Slender white grains.
• Yields 5-7 t/ha under average conditions, but responds
to higher fertilisation.
Milyang 54
• Japonica/indica cross which originally came from Korea.
• About 95 cm tall and matures 140-145 days after sowing.
• Slender white grains, good eating quality.
• Higher yielding than IR64; yields 6-9 t/ha under moderate
management.
• Susceptible to sheath blight particularly in high
rainfall humid areas.
IR 20913
• An advanced selection from the cross between Bhutanese
(Paro) white rice and an IRRI line.
• About 100 cm tall and matures 120-130 days after sowing.
• Yields over 7.5 t/ha under good management.
• Moderate cold-tolerance at flowering, and early maturity
make it suitable for late planting as the main crop.
CROP ESTABLISHMENT
Nursery sowing
• Optimum sowing date: May in dry zone, June in humid
zone.
• Seed rate: 50-60 kg/ha.
• Use clean and healthy seeds.
• Seedlings can be raised using wet or semi-dry bed
methods (see seedling production leaflet).
PREPARATION OF FIELD
Land preparation is one of the important factors that influences
rice yield. It provides good physical, chemical, and biological
conditions of the soil for optimum growth.
• Two or three ploughings are needed, followed by puddling
and levelling.
• Irrigate the field before ploughing, if dry.
• Plough thoroughly and then flood.
• Drain the water slightly and plough, rotovate or harrow
as needed
• A final puddling and levelling may be required just
before transplanting.
Repair and maintenance of bunds and the incorporation of chemical
fertilizers, if any, should be done before the final puddling.
MANURES AND FERTILIZERS
Farmers routinely apply FYM to rice in the medium altitude
areas ranging from 5 to 20 t/ha. FYM contributes significantly
to crop nutrition and soil condition.
Our recommendation is to apply about 5-8 t/ha FYM basally,
and topdress with 35 kg N/ha 35-40 days after transplanting.
If adequate FYM is not available, apply 75:40:0 NPK kg/ha.
Half the N and all the P should be applied as the basal dose.
Topdress the remaining N 35-40 days after transplanting. For
local varieties, limit N to 50 kg/ha to prevent lodging.
Sesbania aculeata (Dhaincha) can be grown for 6-8 weeks then
incorporated as green manure during land preparation. Sow
Dhaincha at a rate of 50-60 kg/ha in April after harvesting
wheat or mustard. Topdress 35 kg N/ha at PI for higher yields.
TRANSPLANTING
Transplanting time: June in dry zone, July in humid zone
Traditional random method can be used if:
• Weed pressure is expected to be low.
• Butachlor will be used.
• The terraces are narrow and small.
Line planting should be done if weeding will be carried out
with a rotary weeder.
• Use a rope to give a row spacing of 20 cm and within-row
spacing of 15-20 cm.
• A plant density of 25-35 per square metre is optimum.
WEED CONTROL
Where weed pressure is low or moderate, 2 hand weedings 20
and 40 days after transplanting are sufficient. Plants should
be closely spaced and the first weeding done no later than
30 days after transplanting.
Where weed pressure is high, use line planting and rotary
weeding. Two rotary weedings 20 and 40 days after planting
are recommended.
If there is no or little shochum but weed pressure is high,
Butachlor is a very effective alternative to rotary weeding.
It is applied 3-6 days after transplanting at the rate of
30-40 kg/ha of 5% "Punch" granules.
If shochum is a major problem it can be controlled by Sanbird
applied at 25-35 kg/ha 4-6 days after transplanting. Alternatively
apply NC 311 at 25-30 kg/ha.
As weeding is laborious, and the use of herbicides is undesirable,
there must be emphasis on indirect complementary weed control
methods like good land preparation, proper water management,
and use of weed-free seedbeds and seeds.
WATER MANAGEMENT
After transplanting keep the water level low for 4-7 days
until the seedlings recover. Water level should then be increased
as the crop grows.
If the supply of water is limited, continuous flooding is
not possible. In this case irrigate at short intervals but
do not let the field become excessively dry and crack. Flowering
is the most critical stage when rice should not be exposed
to moisture stress.
Drain water from the field 10-15 days before harvest to enhance
ripening.
PLANT PROTECTION
Insect pest and diseases are normally not a major problem
in rice at medium altitudes.
HARVEST
Under normal conditions harvesting begins from the first
week of October. Harvest the crop when at least 85% of the
upper portion of panicles turns straw coloured. Some leaves
and stems may still be green at grain maturity, particularly
of improved varieties.
Local varieties shatter very easily, and timely harvest will
minimize grain losses.
For further information contact
Mahesh Ghimiray, Field Crops Sector, RNR-RC, Bajo
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