CLIMATIC ADAPTABILITY/ REQUIREMENT IN RICE

1. CLIMATIC ADAPTABILITY/ REQUIREMENT IN RICE Next End

2. INTRODUCTION • Rice is the seed of the monocot plants Oryza sativa (Asian rice) or Oryza glaberrima (African rice). • As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in Asia and the West Indies. • It is the grain with the third-highest worldwide production, after maize (corn) and wheat, according to data for 2009 Previous Next End

3. In India, rice is grown under widely varying conditions of altitude and climate. • Rice cultivation in India extends from 8 to 350 N altitude and from sea level to as high as 3000 meters. • Rice crop needs a hot and humid climate. • It is best suited o regions which have 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 0C. • At the time of tillering the crop requires a higher temperature than for growth. Previous Next End

4. Temperature require for blooming is in the range of 26.5 to 29.50C. • At the time of ripening the temperature should be between 20-250C. • Photo periodically, rice is a short-day plant. • However, there are varieties which are non-sensitive to photoperiodic conditions. • Rice crop is best suited to tropical and sub-tropical humid climate but it is grown in variety of climate except extreme cold temperate. • The climatic factors that affect rice production are temperature, day length and humidity. Previous Next End

5. TEMPERATURE • The atmospheric temperature has considerable effect on growth and development of rice plant. • Rice needs relatively high temperature for their optimum growth and development. • Temperature requirement of rice is different for different growth stages. • Rice crop can be grown successfully where average air temperature is 210C or more than 210C for 5 to 6 months. • The critical mean temperature for flowering and fertilization ranges from 16 to 20°C. Previous Next End

6. For vegetative growth a temperature range of 25 to 300 C and for grain filling and ripening 20 to 250C temperature was reported best. • High temperature especially during night leads to loss of reserved food through greater respiration. • For higher grain yield a day temperature of 25 to 32°C and night temperature of 15 to 20°C is preferable. • Temperature beyond 35°C affects not only pollen shedding but also grain filling. Previous Next End

7. A higher mean temperature ranging between 25 to 32°C per day would reduce the growth duration and accelerate flowering whereas a mean temperature of less than 15°C would slow during vegetative growth and plants fail to flowers. • Therefore, for vigorous vegetative growth moderately high temperature is required. • It is well known that mild temperature of night and clear sunny weather during day time is better for high yield of rice, but temperature less than 150C is not conducive for panicle initiation as well as for crop growth. Previous Next End

8. SOLAR RADIATION • Clear sunny weather during ripening and moist-humid during vegetative phase is desirable for rice crop. • Low solar radiation would hamper ripening of grains and would increase chaff production enormously. SUNSHINE HOURS • Rice crop prefers brighter and prolonged sunshine for enhanced photosynthetic activity and higher yield. • So, it should receive more than 300 sunshine hours during the last 45 days before harvest. Previous Next End

9. HUMIDITY • Moist humid weather during vegetative growth and dry-sunny weather during ripening is most desirable. • A relative humidity of 60-80 % is said to be optimum. RAINFALL • Rice crop requires about 1400 to 1800 mm water. • Therefore, if this much rain occurs during crop season with well distribution will be sufficient for crop. Previous Next End

10. WIND • High wind velocity or storm is not desirable, as it cause lodging or shattering depending upon the crop growth stage. • Gentle wind is the best for rice cultivation because the supply of carbon di-oxide (CO2) and its utilization is regulated to the maximum. Previous Next End

11. SOIL REQUIREMENT • Rice can be grown in all type of soils like light to heavy soil, except very sandy. • Clay soil is the best for rice cultivation due to its high water holding capacity. Topography • Flat fields having smooth surface are better for rice cultivation as it facilitates even and equal distribution of water. Previous Next End

12. Texture • Clay, silt clay, silt clay loam, textures of soil are best for Paddy crop. pH • Slightly acid soils having a pH value of 6 to 7 are better for paddy cultivation. • However, it has been found to be grown in a wide range of pH varying from 4 to 8. Previous Next End

13. CROPPING SEASON Three Seasons for Rice Cultivation in IndiaThere are three seasons for growing rice in India. These three seasons are named according to the season of harvest of the crop. • Autumn Rice/Pre-Kharif Rice • Summer Rice/Rabi Rice • Winter Rice/Kharif Rice Previous Next End

14. The Kharif season is characterized by a gradual fall in temperature, more numerous cloudy days, low light intensity, a gradual shortening of the photoperiod, high relative humidity and cyclonic weather. • During Rabi, there is a gradual rise in temperature bright sun shine, near absence of cloudy days, a gradual lengthening of the photo period and lower relative humidity Previous