India is a large country. The wide variety of terrain leads to a wide variety of climatic conditions. These range from permanent snowfields to tropical coast lands; from areas of virtual desert in the north-west to fertile, intensively cultivated rice fields in the north-east. Generally, we consider India to lie between 8° and 35° N latitude, with a tropical and sub-tropical climate. The subcontinent has eight climatic zones all of which only have the monsoon rains in common. But even the monsoon comes to different parts of the country at different times.
Different Climatic Factors Affecting Rice Cultivation in India
There are many varieties of rice which are cultivated with differential response to climatic factors, such as :
Rainfall is the most important weather element for successful cultivation of rice. The distribution of rainfall in different regions of the country is greatly influenced by the physical features of the terrain, the situation of the mountains and plateau. The regions experiencing very heavy rainfall in the country are :
Temperature is another climatic factor which has a favorable and in some cases unfavorable influence on the development, growth and yield of rice. Rice being a tropical and sub-tropical plant, requires a fairly high temperature, ranging from 20° to 40°C. The optimum temperature of 30°C during day time and 20°C during night time seems to be more favorable for the development and growth of rice crop.
Day length or Sunshine
Sunlight is very essential for the development and growth of the plants. In fact, sunlight is the source of energy for plant life. The yield of rice is influenced by the solar radiation particularly during the last 35 to 45 days of its ripening period. The effect of solar radiation is more profound where water, temperature and nitrogenous nutrients are not limiting factors. Bright sunshine with low temperature during ripening period of the crop helps in the development of carbohydrates in the grains.