rice ecosystems h ados training 7 june 2011

8/6/2019 Rice Ecosystems H ADOs Training 7 June 2011

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CSISA 1

CEREAL SYSTEMS INITIATIVE FOR SOUTH ASIA (CSISA)

7 June 2011, IRRI Office, Dhaka



CSISA 2

Systems of Rice Culture/Rice Ecosystems

An ecosystem is a biological environment consisting of all the

organisms living in a particular area, as well as all the

nonliving, physical components of the environment with which

the organisms interact, such as air, soil, water and sunlight.

Components:

Systems of growing rice: to suit specific environments and

socio-economic conditions of the farmers

Soil/land

Crop management practices



CSISA 3

Classification of Rice Culture/Ecosystem

According to source of water supply: Rainfed (Aus, Aman)

Irrigated (Boro)

Based on land and water management practices:

Lowland (wetland preparation of fields): T. Aus, T. Aman

Upland (dryland preparation of fields): B. Aus

According to water regime:

Upland, with no standing water, no bunds

lowland, with 5-50 cm of standing water with bund

Deepwater, with > 51 cm to 5-6 m standing water



CSISA 4



CSISA 5

In Bangladesh the rice-growing environment has been

classified into three major ecosystems based on

physiography and land types.

These ecosystems are-

a) irrigated,

b) rainfed, and

c) floating or deepwater.

The rainfed ecosystem has been further classified as-

rainfed lowland and

rainfed upland

Rice Ecosystems in Bangladesh



CSISA 6

Rainfed Ecosystems

Rainfed rice: The bulk of the rice is produced in the wet

season:

dependence of rainfall

rainfall is the most limiting production constraint for rainfed

rice culture

Rainfed Upland rice (during March to July)

Rainfed lowland pre-monsoon: T. Aus (during April to

August) and

Rainfed lowland monsoon: T. Aman (during July to

December)



CSISA 7

Rainfed Upland rice (DS Aus):

Broadcast in to dry soil

Drilled in to dry soil

Dibbled in to dry soil (to escape drought & salinity)

Constraints:

The yield potential of this crop is the lowest due mostly to the

unfavorable weather.

The second important constraint is the lack of high yielding varieties.

Unpredictable distribution of rainfall hinders timeliness of some

management practices, particularly fertilizer management.

Thirdly, the climatic conditions are very much conducive for rapid

growth of weeds and pest and disease infestation.

Rainfed upland rice



CSISA 8

In Bangladesh, rainfed lowland rice by direct seeding on to

non puddled soil at the beginning of the rainy season

is known as aus (meaning early)

The rice is direct seeded in March-April and harvested in

July-August

Early maturing varieties are more essential than

transplanted rice

varieties should have good drought tolerance

Rainfed upland rice: contd----



CSISA 9

Rainfed lowland pre-monsoon rice (Aus: meaning early)

Rainfed lowland monsoon rice (T. Aman: meaning safety or

stability): (including medium deep stagnant water; 50-100 cm)

Enough water has to accumulate in the field to soften the soil before

plowing can be done Dikes/bunds are essential for rainfed culture because the undependable

water supply must be captured and controlled

Land is either prepared wet or dry but water is always held on the field

The establishment methods are:

- transplanting in puddled soil.

- WSR on puddled soil and

- direct seeded in to dry soil

Rainfed lowland rice



CSISA 10Rainfed upland rice: dry DSR

Irrigated lowland rice: TPR

Rainfed lowland rice: TPR

Rainfed lowland rice: WSR



CSISA 11

T. Aus, the wet season first crop, is grown when sufficient rainfall occurs

during April to August.

This is the period experiencing higher temperatures with minimum diurnal

fluctuation, moderate humidity during the reproductive stage, but

with occasional scanty rainfall during the early vegetative growth

period.

Such a climate is very much conductive to higher vegetative growth of the

crop with the lowest partitioning coefficient and

development of pests and diseases.

Rice varieties grown are all insensitive to photoperiod and mature within

110 to 130 days.

Therefore, climatic limitation is the most important constraint for this rice.

Rainfed lowland pre-monsoon rice: T. Aus



CSISA 12

� The wet season second crop grown in the rainfed lowland ecosystem is

known as T. Aman, cultivated during full monsoon period.

� The crop experiences high rainfall and temperature during the vegetative

stage and low temperature often associated with drought during

the reproductive stage.

� Since the Aman crop experiences two extreme climates at two ends,planting time is very important for this rice but often farmers cannot

follow the appropriate planting schedule due to various socio-

economic factors and delayed on set of rainfall. This late planting

causes yield decline.

� To save the crop from low temperature stress at the reproductive stage

and also to establish a rabi crop timely after the harvest of Aman,

shorter duration varieties with less or no sensitivity to photoperiod

have been evolved recently for cultivation in shallow flooded areas.

Rainfed lowland monsoon rice: T. Aman



CSISA 13

Coastal rice belongs to tidal wet land rice

This ecosystem includes both saline and non-saline ecologies.

In non-saline: single T. Aman, Boro-T. Aman, T. Aus-T. Aman CPs

In saline: single T. Aman, Boro/sesame/mungbean- T. Aman, Boro-

Shrimp/Prawn-Fish, T. Aman+ Fish CPs

Local varieties with taller seedling is used.

In the medium flooded area, harvesting of Aman rice in standing

water at the harvesting time, photo period sensitive var, better.

In saline ecologies, the only MV is practiced BR23 which can tolerate

stagnant water, some salinity, taller plant height, non-lodging, less sterility

There is little scope for further expansion of MVs unless varieties with

relatively higher growth rate in the nursery bed, sturdy culm and

profuse root system are evolved.

Special Ecosystem: Tidal saline and non saline wetlands



Fig. Top soil salinity of Kismat Fultala, Batiaghata, Soil series: Dumuria (MHL)

0

5

10

15

20

25

30

35

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

S a l i n i t y

(

2006 2007 2008 2009

Fig. Water salinity of Pasur river, Mongla port , Mongla, Bagerhat

0

5

10

15

20

25

J F M A M J J A S O N D

Month

S a l i n i t y

( d S

2006 2007 2008 2009

14CSISA



CSISA 15



CSISA 16

Major crop management in Rainfed lowland rice

Transplanted rice:

In general, modern semi-dwarf varieties are grown in shallow rainfed

lowland (30 cm) rice growing area

Taller varieties with or without photoperiod sensitivity in medium deep LL

The maturity is controlled by short days (< 12 hrs) and cool climate (<27 0c) particularly during the reproductive and ripening phases of crop

growth

Aman crop is often subjected to flash flood and reduction in stand due to

seedling submergence needs submergence tolerant variety

Seedbeds starting with the onset of the monsoonal rains

Seeds are soaked for 24 hrs and then incubated for 48 hrs

In wet seedbed with 80-100 g/m2 of seedbed



CSISA 18

Wet-seeded lowland rice

Pre-germinated seeds are broadcasted or drilled on to puddled fields

without much standing water

Stand establishment is often poor because of poor land preparation,

weed competition and poor water control

Early maturing variety (about 100- day duration) are preferred

Where rainfall distribution is good and farmers can puddle the fieldsquickly and thoroughly

Dr y seeded lowland rice

Establishment of dry seeded rice in lowland fields must be in accord with

the local rainfall pattern

To obtain high yields with direct seeded rice optimum time of planting

based rainfall pattern, good weed management, optimum fertilizer

management (N, K) are necessary



CSISA 19

Transplanted rice

Drilled/broadcast onto puddled soil (WSR by drum seeder)

Irrigated rice is grown after the harvest of T. Aman rice or after

harvesting a non-rice crop like potato, mustard or quick growing

vegetables.

Low temperature during the early vegetative stage of the crop prolongs

growth duration and thus most of the existing modern varieties

mature within 165 days.

This requires use of a high level of inputs like irrigation, fertilizer and plant protection measures.

Of all the constraints of Boro rice cultivation, the most pressing

one is the availability of irrigation water followed by farmers

incapability of using the required amount of fertilizer in a balanced

Irrigated lowland rice: Boro



CSISA 20

Farmers of some regions delay planting in order to shorten growth

duration vis-à-vis the production cost, particularly of irrigation. This

delayed planting, however, reduces yield significantly.

Recently BRRI released relatively shorter duration Boro varieties. But

some farmers without being fully aware of the appropriatetechnologies for such varieties often stick to their traditional

practices of early transplanting, subjecting the crop to cold injury

during the flowering stage and thus realize poor harvests.

With ideal conditions, it is possible to obtain similar high grain yield with

rice transplanted or direct seeded in puddled soil.

Irrigated lowland rice: Boro-contd---



CSISA 21

To obtain high yields with direct seeded rice optimum time of planting,

precise water management, good weed management, optimum fertilizer

management (N, K) are necessary

Aus area-9%, Aman -48 % and Boro-43 % of total rice

area (10.58 m ha): BBS, 2009

Irrigated lowland rice: Boro-contd---



CSISA 22

Broadcast onto dry soil

Transplanted

This is a very long duration crop sown in March/April and harvested in

November/December.

This rice requires a special habitat of prolonged flooding.

The varieties are strongly sensitive to photoperiod and low tillering,

producing a very high amount of biomass but with the least HI.

The most important constraints of this rice are lack of varieties with high

yield potential, unpredictable flooding, and low response to

fertilizers.

The maximum water depths vary between 51-100 cm for ,ore than half of

the growth duration and sometimes there is completely

submergence of the plant. The depth of water, duration of flooding, the rate of increase in water level,

temperature, turbidity, and time of occurrence, vary for different

areas, so that the term deepwater may have different meanings in

different countries.

Deep water/floating rice



CSISA 23

rice ecosystems h ados training 7 june 2011

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