On the basis of criteria of homogeneity in agro-characteristic such as water surplus and water deficit, India was divided into 11 agro climatic zones.Later on, India was divided into 15 agro climatic zones on the basis of water surplus, water deficit and cropping system. The agro climatic zone are given below:

The grain is mature and fully developed, when it is hard and free from green tint, the panicle at this stage bends in the shape of an arc. In some varieties the stem and the upper leaves may still remain green.

 

Drying is the process that reduces grain moisture content to a safe level for storage. Drying is the most critical operation after harvesting a rice crop. Delays in drying, incomplete drying or ineffective drying will reduce grain quality and result in loss

 

Grain cleaning after harvest is important as it removes unwanted materials from the grain. Clean grain has a higher value than grain that is contaminated with straws, chaff, weed seeds, soil, rubbish, and other non-grain materials. Grain cleaning will improve the storability of grain, reduce dockage at time of milling, and improve milling output and quality.  Seed cleaning will reduce damage by disease, and improve yields. Following are some general guidelines for cleaning grain and seed.

 

Drainage of water from the field can be very important during the time of crop establishment, high rainfall events and during attacks by crop pests.

 

Weed competition is one of the most important yield limiting biotic constraints in rice culture. There may be more than 100 weed species that cause problems in rice, but many are of little concern to the farmers. The number of species that comprise the major portion of the weed flora in any rice field is usually less than 10 (Moody and Drost 1983).