Harvesting Rice crop should be harvested when the grains become hard and have about 20 % moisture in them though the plants still remain green. Usually the crop comes to harvesting between 25 - 30 days after completion of flowering. Harvesting is generally done when 85% of the grain is straw colored or 2/3 of the rachis (main axis of panicle) is dry. If the crop is harvested early, the produce contains high moisture and more Immature grains. The yields will be low due to unfilled grains. It is very difficult to store produce as shriveled grains with high moisture are prone to primary infestation of Pests. Late harvesting results in shattering of the grains, germination even before harvesting during rainy season and breakage during processing. Hence harvesting at correct time is essential to get good quality grains and higher yield. Crop can be harvested at physiological maturity or at harvest maturity. Crop is considered to be at physiological maturity when the translocation of photosynthate is stopped to economic part. The moisture content falls steeply from 40 per cent to 20 per cent which is an indication of attaining physiological maturity. Harvesting time generally depends on season, temperature, rainfall, available sunshine and cultural practices. 7 - 10 days prior to harvesting, the water from the field has to be let out and the soil is allowed to dry. The dryness of soil facilitate easy harvesting of the crop nearer to the ground level. Criteria for harvesting Should be carried around 32 days after flowering. Green grains not more than four to nine per cent. Percentage of milky grains less than one per cent. Moisture contents of grains less than 20 per cent. 80 per cent panicles straw colored and grains in lower portion of panicle in hard dough stage. At least 5 hills are to be studied at maturity. Method of Harvesting Harvesting is done either Manually or by Mechanical means. In manual harvesting, sickle is the most important tool. Manual The sickle has to be sharp, curved and serrated for efficient harvesting. Mechanical In the event of labour shortage or in periods of peak labour demand mechanical harvesting is favored. Combined harvester Combined harvestor are used for harvesting. Combines perform several operations. It cuts the crop, separates the grain from straws, cleans it from chaff and transports the grains to the storage tank. The combines only reaps 2 - 9 rows at a time depending on its size and horse power. Use of these combines for harvesting is limited to large holdings. The simple machines useful for harvesting in small holdings are also available. These machines cost about Rs. from 25,000 to 40,000. These machines are run by diesel oil. With these machines in a day of 6 hours about 1 hectare can be harvested. Self propelled paddy reaper During peak harvesting season when a large area comes for harvesting at a time, farmers are facing problems due to labour shortage. To over come the above problems there is a need for Mechanical paddy harvestor The machine can be recommended for harvesting paddy in all types of soils except in black cotton soils when the soil moisture is more than 25%. The machine will not cut lodged crop. The reaper for harvesting paddy at high soil moisture conditions is similar to that of self propelled vertical conveyor reaper Modified cage wheels (with leaf type lugs) were provided. Here the drive for cutting mechanism is taken from 5 H.P diesel engine. The engine runs at 1500 RPM. The machine has gear drive to the driving wheels. The drive is taken to the cutter bar and conveyor belts through bevel gear system. The speed reduction from engine to ground wheels and to cutter bar is done with the help of belts, pulley and set of gears. The reduction from engine is such that the machine speed in the field is about 2 to 3 Km/hr and the cutter bar speed is about 300 strokes per minute. Two clutches are provided for easy turning. A main clutch is also provided to disengage the drive whenever it is not required. The I.R.R.I. model paddy harvester It runs by a 5 H.P. diesel engine and requires one man to operate the machine. It cuts the paddy crop and leaves it on the field in windrows on one side of the machine. Before harvesting the corners of the plot should be harvested manually so that the machine will enter the field and is enable to turn at the corners. The field coverage capacity is 4 acres/day. But this machine is suitable only when the field is completely dry at the time of harvesting. If there is high soil moisture in the field then the machine will not work and also it is not suitable for harvesting paddy in coastal area during the Kharif season where paddy is harvested even in water logged conditions. The cost of the machine is about Rs.32,000/-. This machine is commercially manufactured by M/s. Swathi Industries, Coimbatore Problems in Harvesting Problem arises especially when it coincides with heavy rain or cyclones. The crop may be submerged and the seeds may start germinating on the plant itself. This can overcome by growing dormant varieties. The other way of saving the crop is by spraying 500 ltr/ha of 25 per cent salt solution at harvesting maturity by 8 days. Threshing After harvesting, the cut plants are spread in the field and after 2 - 3 days they are piled up in the threshing floor (or) in the field itself. Depending on the marketing position and environmental conditions threshing may be undertaken from 15 days to 2 months from the time of pileing. Immediate threshing after harvesting results in less broken rice. Delayed threshing deteriorates the quality of the grain. Manual For manual threshing we can use threshing table. Mechanical Tractor threshing This is commonly followed because of the time and labour saving. Thresher The thresher is made up of a combination of several different machines, each having a special and separate function to perform in the separation of the grain from the straw. The thresher is a very efficient machine, when properly operated and given reasonable care it is durable and given a high degree of performance. It not only threshes, separates, but also cleans the grain thoroughly. It also delivers the straw to the stack. Functions of Thresher The work performed by a thresher can be divided into four separate functions, which are To feed the grain to the threshing cylinder. To thresh the grain out of the head To separate the grain from the straw To clean the grain and delivered it to the outlet. In the cleaner, the grain passes over a series of sieves and screens through which flows a stream of air created by a fan. The larger and heavier sections of straw are held on the sieves, while the blast of air blows out the finer chaff. The width of the thresher at the cylinder and at the rear determines its size. By changing the speed (revolution per minute) of the cylinder and changing the sieves and screens, a thresher may be adapted to thresh different crops. Multi crop thresher This machine is useful for threshing paddy, wheat, maize, jowar, bajra, ragi and others quickly and economically, it can work with either a 5 HP electric motor, or diesel engine. The crop is manually fed into the threshing cylinder. In case of paddy and wheat,the entire crop is fed through the machine. Quantities of various crops that can be threshed per hour are; paddy 6 to 8 quintals, Wheat 4 to 6 quintals, Jowar 10 to 12 quintals and Maize 10 to 12 quintals. The approximate cost of the machine is Rs. 30,000/- Japanese paddy Peddle Thresher This is manualy operated, is also used for threshing small quantities of harvested paddy. A single person with the help of a pedal operates this thresher. Threshing of paddy is done by holding the bundle of sheaves against the teeth of revolving drum. Power operated threshers are also available now a days and they are being used for threshing and also winnowing The machines having 5 HP power are able to thresh 6 - 10 quintals of rice in an hour. 4 persons are required to feed the sheaves into machine. This type of machine cost about Rs. 35,000/- exclusive of motor.

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