Crop growth depends on both internal and external factors. The internal factors are mostly genetic or hereditary, in nature, which include high yielding capacity, resistance to lodging, tolerance to abiotic conditions like drought, flood and salinity, and also, tolerance to biotic conditions like both insect and pest attack. The external factors include climate, edaphic, biotic, physiographic and socio-economic factors. Climate influences the yield potential of a crop. Nearly 50% of the crop yield is attributed to climatic factors. The climatic factors are mostly abiotic which affect plant growth and development. Such factors which affect plant growth, development and crop productivity are, water availability, temperature, solar radiation, atmospheric humidity, wind velocity and atmospheric gases. However, solar radiation, temperature and rainfall are the most important of these.