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Graminae
Common names
Rumput melayu (Malaysia).
Description
A very robust species reaching a height of 2 m, the spikelets
are unawned (Bor, 1960), 8- 10 mm long, sessile, pedicel less than one-third
the length of the sessile spikelet. It is a perennial, open-tussock grass
with stout culms and a very strong root system.
Distribution
Malay Peninsula, Burma and Borneo.
Season of growth
Perennial.
Rainfall requirements
It grows under high-rainfall conditions in Malaysia between
2 000 and 4 000 mm (Ng, personal communication).
Drought tolerance
It is moderately tolerant of drought during the dry season
in Malaysia.
Soil requirements
It has a wide soil tolerance heavy clays, sands and marine
peats.
Ability to spread naturally
It spreads rapidly by shattered seed.
Land preparation for establishment
It will establish either by planting seed in a well-prepared
seed-bed or by oversowing vegetative clumps into uncultivated fields (Ng,
personal communication).
Sowing methods
It is sown by seed into a prepared seed-bed or by broadcasting
root-stocks 1 m apart.
Sowing depth and cover
The seed should not be sown deeper than 4 cm. Germination is
as good with surface sowing as with deeper planting in laboratory tests.
Sowing time and rate
In Malaysia it can be sown at any time when soil moisture is
adequate.
Number of seeds per kg.
About 420 000.
Seed treatment before
planting
Dehulling the seed caused a rapid incease in germination in
the laboratory, but may lead to infection by soil micro-organisms and poor
field germination (Ng & Wong, 1976).
Tolerance to herbicides
Highly tolerant.
Seedling vigour
Early growth is slow.
Vigour of growth and growth
rhythm
It is not as vigorous as introduced tropical grasses.
Response to defoliation
It will stand heavy grazing and slashing, becoming more prostrate
in habit.
Grazing management
This grass has not been subjected to grazing management trials.
It is usually burnt yearly to obtain new growth.
Response to fire
It withstands fire very well.
Dry-matter and green-matter
yields
In Malaysia a three-year mean yield of 13 740 kg DM/ha was
achieved with an application of 224 kg N/ha per year. With the legumes
calopo and tropical kudzu, the three-year mean was 10 812 kg DM/ha, and
with siratro, 9 881 kg/ha per year when fully fertilized with basic fertilizer
and trace elements. It was comparable with Brachiaria decumbens in yields
alone, with nitrogen, and with legumes (Ng & Wong, 1976). Peak yield
came from a ten-week cutting interval.
Seed yield
17 kg/ha have been harvested by hand from 40 days' regrowth,
but loss of seed from bird attack was severe (Ng, personal communication).
Diseases
No serious diseases.
Main attributes
It is indigenous to Malaysia and seed is cheap. It stands heavy
grazing. It tolerates a wide range of soils and is liked by cattle.
Main deficiencies
Its seed shattering and tendency to become a weed.
Optimum temperature for
growth
30-35°C.
Minimum temperature for
growth
No record is available. It grows at night temperatures of 22-24°C
in its native habitat.
Frost tolerance
It is probably not tolerant of frost.
Latitudinal limits
It occurs mainly between 20°N and 5°S.
Response to light
It tolerates shade well.
Maximum germination and
quality required for sale
No standards are available in Malaysia. Germination is usually
28-35 percent.
Pests
Mainly bird attack.
Palatability
It is quite palatable until maturity.
Response to photoperiod
It appears to be day-neutral, flowering throughout the year
in Malaysia with a day-length variation of only 30 minutes throughout the
year. Peak flowering is in October-November.
Chemical analysis and
digestibility
I. magnum produced 846 kg/ha crude protein per year, about
100 kg/ha more than B. decumbens in Malaysia. Its crude protein content
averaged 6 percent of the dry matter.
Natural habitat
In open spaces and in shade.
Tolerance to flooding
It is highly tolerant of flooding and waterlogged conditions.
Fertilizer requirements
It responds well to fertilizers.
Compatibility with other
grasses and legumes
It competes well with Imperata cylindrica, and the legumes
Centrosema pubescens and Stylosanthes guianensis are compatible with it.
Seed production and harvesting
It produces abundant viable seeds, but ripening is uneven and
the seed shatters readily. The best stage for harvesting is when the seed
heads still retain some greenish tint, yet the spikelets are easily detached
from the rachis by rubbing between the fingers.
Economics
A productive indigenous grass in natural stands in Malaysia.
Further reading
Ng & Wong, 1976.
Dormancy
There is no post-harvest dormancy.
Value for erosion control
Because of its erect habit, it is not as useful as prostrate
species.
Animal performance
No research figures are available.
Tolerance to salinity
Not known.
Ability to suppress weeds
Good. It may be a weed itself in certain areas.
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