Climatic requirements
Rice is a heat and water loving plant requiring high temperature and adequate moisture supply. For germination, a minimum of 10 ºC and for flowering a temperature of 22-25ºC is considered as an optimum. Grain formation takes place at 20-21ºC. Low temperatures particularly during 10-11 days before heading causes considerable loss in grain yield because of sterile spiklets. A ripening temperature should be in between 20-25 ºC. It is best suited in regions having high humidity, prolonged sunshine and an assured supply of water. The average temperature required throughout the life period of the crop ranges from 21 to 37 ºC. The crop requires higher temperature at the time of tillering than for growth.

Photo periodically rice is a short day, thermo sensitive plant but there are many varieties developed which are thermo insensitive. It is mainly grown in areas receiving 1000- 1500 mm rain. Crop needs heavy rains (125 mm) during vegetative phase and 200 mm monthly rain for low land and 100 mm for upland rice. In India, it is grown from 8 to 35º north latitude and from sea level to mountainous region up to 3000 meters. Heavy winds specially after heavy rainfall or heavy irrigation results in severe lodging. Where winter temperatures are fairly low only one crop of rice is taken during kharif season. There are three seasons for growing rice in India but in Gujarat, now days rice is taken in kharif and summer seasons where assured irrigation facilities are available. The rice variety IR - 28 is a non-sensitive to the photoperiod and is grown in any temperature and time period.

Soil
Soils having good water retention capacity with good amount of clay and organic matter are ideal for rice cultivation. Clay or clay loams soils are most suited for rice cultivation. Rice being a semi-aquatic crop grows best under submerged conditions. A major part of rice crop in the State is grown under low land conditions. It grows well in soils having a pH range between 5.5 and 6.5 including alkaline and acidic soils.