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Time and stage of harvest and harvesting techniques for rice

Abstract:

Identification of maturity and correct stage of harvest is one

of the most important aspects in rice cultivation.

Premature harvest of rice affects the quality due to ill-filled

and chaffy grains and over matured harvest induces

shattering.

Some of the factors considered while deciding time of

harvest of rice are economic part aimed, products utility and

post harvest storage.

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Manual and mechanical methods of harvesting are the

two methods of harvesting of rice crop, decided

depending upon the purpose, time and labour

availability.

Though manual methods are used for many decades in

developing countries, mechanical methods of rice

harvest not only resolve the present day labour crisis,

but also, cost and time.

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Learning objectives:

To learn the maturity symptoms and of various criteria of harvesting

rice crop.

To study the harvesting time, stage and methods; and machineries

available for harvesting of rice.

Introduction:

Rice is the most important food crop of the world.

Higher production and quality of rice not only rely on cultivation but

also, harvesting of rice.

Right time of rice crop harvest is one of the most important factors to

get higher yield and good quality producePrevious Next End


Premature or delayed harvest often adversely affects

quality of the produce.

Physiological and harvest maturities are two maturity

judgments made in rice crop to decide the harvesting time.

At physiological maturity (during which the translocation

of photosynthates stops), the rice panicles completely

matures at top and few grains at bottom at immature stage.

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Whereas, during harvest maturity the crop looks dried

appearance due to drying of all most all the leaves.

Harvesting may be the most important operation in rice

and the farmers are following traditional techniques for

harvesting rice, but new equipments and machineries are

introduced to nullify the labour problems.

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I. TIME OF HARVESTING

Yields of rice crop are expected high when it is harvested the

economic product is at its optimal quantity and quality.

Ideal time to harvest of rice depends on a number of factors,

including the economic part, utilization of the product and

post harvest storage.

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Economic part

The economic product in rice is mainly grain and straw is also used

for cattle.

Rice is to be harvested when the grain is fully matured and filled so

as to get maximum quality and quantity.

Utilization

Rice grain is either used as grain (for human food) or seed. If the

produce is used for grain, harvesting date can have flexibility but,

not for seed.

Immature seeds spoil germination whereas, over dried seeds form

splitting and cause germination.

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Post harvest storage

Rice after harvest need to threshed and dried to safe moisture (<14%).

Maturity

Rice can be harvested at physiological maturity or at harvest maturity or storage maturity depends on situation or need of produce.

Physiological maturity

Physiological maturity refers to a developmental stage after which no further increase in drymatter in the economic part

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In rice, moisture content of grains is

very high during milking stage and it

gradually deceases due to

accumulation of photosynthates.

Sudden fall of moisture content from

40% to 20% is an indication of

attaining physiological maturity.

The grains at this stage are of hard

dough consistency. Physiological maturity symptom of

ricePrevious Next End


If grain is harvested prior to its physiological maturity,

it would have low drymatter, poor quality and will

shrivel upon drying.

Golden yellow colour of the grain and senescence of

lower leaves are the key symptoms of physiological

maturity of rice.

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Harvest maturity

Harvest maturity for a crop is when the product of interest is at

best quality and maximum yield.

Harvest maturity generally occurs 7-10 days after physiological

maturity in rice.

The important process during this period is loss of moisture

from the plants and grains.

Hard and yellow coloured grains, golden yellowing of leaves

are the important symptoms of harvest maturity in rice.

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Harvest maturity symptoms of rice

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Storage maturity

When there is no scope or chance for post harvest drying,

the crop is to be harvested at a stage where it can be

directly stored.

For grains, <14% moisture content is advocated.

Generally, in rice, harvest maturity is advocated because;

it avoids both immature of grains (due to physiological

maturity) and splitting of grains (due to storage maturity).

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II. STAGE OF HARVEST

Determination of harvesting date is easier for determinate crops

like rice. The following are the criteria for harvesting of rice

crop.

30-35 days after flowering

Less than 4-9% green grains in a panicle

Milky grains in a panicle - less than 1%

Moisture content of grains - less than 20%

About 80% of panicles are straw coloured and grains in lower

portion of panicle is in hard dough stage.

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III. HARVESTING TECHNIQUES

Two methods are followed in different countries for

harvesting of rice crop, largely depending on timely labour

availability and costs associated with harvesting.

Manual harvesting of rice is still the major method of harvest

in developing countries since the combined harvesters may

spoils the straw, while mechanized harvesting dominates in

developed countries and river basins where the transplanting

and harvesting of rice in large areas at oncePrevious Next End


Manual harvesting

Manual harvesting of rice is most common in under-

developed and developing countries.

The sickle is the most common and the major traditional

tool for harvesting.

The output is low and the effort required for operation is

high.

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Manual harvesting of rice

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Mechanized harvesting

Machines are available for harvesting rice. The machine cuts

the paddy stubbles and laid down the harvested crop in the

field.

Later, the harvested rice stem should be bundled and stacked in

a dry place if not threshed immediately.

Combine harvester

The combine harvester combines operations such as cutting,

handling, threshing and cleaning.

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The combine paddy harvester can harvest about 4 ha/day and

can be operated in fields as small as 30 cents.

It needs only a driver and helper to operate the machine.

There is no wastage of grains and the cost of operation is equal

to the wages paid for manual labour.

Combine harvesting of rice has been accepted by farmers

in regions with labour shortage during harvesting period.

These are more suitable for custom hire service.

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Combine harvester

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Summary:

The main factors considered for deciding for time of

harvesting are the economic part, utilization of the product

and post harvest storage.

Main economic parts in rice are grain and straw and

harvesting after maturity provides good quality of grains.

Rice can be harvested at physiological maturity or at

harvest maturity or storage maturity depends on situation

or need of produce.Previous Next End


Golden yellow colour of the grain and senescence of

lower leaves are the key symptoms of physiological

maturity of rice.

Hard and yellow coloured grains, golden yellowing of

leaves are the important symptoms of harvest maturity in

rice.

Rice grains are stored at <14% moisture content.

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About 80% of panicles are straw coloured and grains in lower

portion of panicle is in hard dough stage is the main symptom of

harvest of rice.

Harvesting of rice is done in two methods, viz., manual and

mechanical means.

Sickle is the most prominent tool used for harvesting rice manually;

whereas, combined harvesters do the job in mechanical means.

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