Seed has been an important agricultural commodity since the first crop plant was domesticated by pre-historic man. For thousand of years, man cleaned seed of his food crops by winnowing. This is still an important process, but it is no longer adequate to supply the kind of seed needed by farmer.
Seed processing is a vital part of the seed production needed to move the improved genetic materials of the plant breeder into commercial channels for feeding the rapidly expanding world population. The farmer must get the quality seed that is free from all undesired materials because farmer’s entire crop depends on it.
Seed can seldom be planted in the condition in which it comes from the growers. In fact, many seed lots contain weed or crop seed or inert material that make them unfit for sale without processing. Crop seed also frequently have stems, awns, clusters or other structures, which prevent from flowing through the drill freely.
Seed processing is that segment of the seed industry responsible for upgrading seed (Fig. 1), improving planting condition of seed, and applying chemical protectants to the seed.
Advantages of seed processing:
Make possible more uniform planting rates by proper sizing
Facilitate uniform marketing by providing storage from harvest time until the seed is needed for planting.
An important factor to consider is the moisture content of the seed prior to processing. Seed with moisture content above 15% are subject to excessive damage in the processing line. In this case natural or artificial drying may be necessary.
Physical characteristics used to separate seed include size, length, weight, shape, surface texture, colour, affinity for liquids and electrical conductivity.
Seed processing can broadly be divided into various steps (Fig. 2). As the seed is received into the processing plant, it goes either directly into the cleaning process or into storage to await processing. Drying may be necessary. As processing begins, the first phase (conditioning and pre-cleaning) consists of scalping, debearding, shelling or any other operation necessary to make the seed flow easily. The second phase (cleaning and grading) includes the removal of inert materials, weed seed, other crop seed, and broken seed that are larger or smaller than the crop seed and obtain the seed mass in the uniform size range of perforations of top and bottom screen.
After the desired purity is obtained, seed enters the final processing phase of separation based on specific characteristics like length, weight etc and treating and packaging. Processed seed is stored for later sale.
India is one of the major rice growing areas in the world and it is consumed by more than half of its population. The increase in rough rice production in the last few years is mainly due to the Green revolution and the introduction of high yielding varieties.
Orissa is major paddy growing state. The area under production is 4500000 ha with production of 7148400 tonnes and yield in the state is 1589 kg/ha. The paddy yield in the state is very low as compared Punjab and Tamilnadu where the yield is 3346 and 3579 kg/ha, respectively. The non-availability of good quality seed is one of the main reasons of it. The sowing and harvesting time of paddy in the state is given in Table1.
Table 1. Sowing and harvesting time of paddy
India’s certified/quality seeds production/distribution of last five years is given in Table 2, which indicates that the requirement of certified seed is increasing year after year.
Table 2. Production/distribution of certified/quality seeds in the country
(Source: Economic survey of India, 2000-2001)
The production of paddy in the year 1996-97 was 81.30 MT. The target fixed for year 2011-2012 is 128.12 MT. For achieving this target, the gap (Table 3) between demand and supply of certified/quality paddy seed should be minimized by creating seed production and processing facilities in the state involving private sector at larger scale.