Rice is cultivated in India under widely varying condition of altitude and climate. It is grown in almost all types of soils including alkaline and acidic soils. In fact, rice plant has got wide physical adaptability. Therefore, it is grown from below sea level (Kuttanad area of Kerala), upto an elevation of 2,000 meters in Jammu & Kashmir, hills of Uttranchal, Himachal Pradesh and North-Eastern hills (NEH areas). Hence, rice growing seasons vary in different parts of the country, depending upon temperature, rainfall, soil types, water availability and other climatic conditions. The productivity of rice varies very much from one region to another region, from one season to another season etc. due to various reasons such as imbalance use of fertilizers, soil moisture stress, incidence of insect pests and diseases etc. The reasons are discussed below :

1. A number of high yielding varieties have been released for general cultivation but out of this more than 90% varieties are for irrigated eco-system and very few improved varieties are available for rainfed eco-system, which constitutes more than 60% of cultivated rice areas in the country.

2. High yielding varieties are fertilizer responsive/oriented. Yet, the farmers are using much less fertilizer per unit cropped area than their counterparts in South and South-East Asian Countries. There is vide disparity in fertilizer use within the country. The States like Tamil Nadu and Punjab use as high as 100-150 kg. as against 20 kg/ha in Assam, Orissa and Madhya Pradesh. In Eastern Region, rice area is about 59% but fertilizer consumption is low, resulting in poor productivity.

3. Transfer/adoption of improved production technology in harsh rainfed eco-system has not picked up its desired momentum. Therefore, productivity of rice in these eco-system is considerably poor.

4. The complex ecological situation of rainfed eco-system consisting of upland, shallow low land, semi-deep water and deep water conditions is one of prime reasons for low productivity. In fact, about 60% of the total rice area in the country is concentrated in rainfed eco-system and it is contributing about 45% to the national production of rice, but rainfed eco-system is handicapped with varied natural, socio-economic, organizational and technological constraints resulting in low productivity.

5. Out of 45 million hectares of total rice in India, upland rice occupies about 7 million hectares, of which 6 million hectares are concentrated in Eastern India comprising of Chhattisgarh, Eastern Uttar Pradesh, Bihar, Orissa, West Bengal and Assam and these states together constitute about 13.5% (upland) of total area under rice in the country. It is often found that upland rainfed crop suffered due to soil moisture stress at critical crop growth stage including drought, lack of resistant/ tolerance of diseases and pests, in adequate plant population and low nutrients status of soils are responsible for low productivity of rice in upland areas.

6. Rice area is more in Eastern states and these states are facing drought situation frequently and irrigation facilities is not sufficient to offset hazards exist by vagaries of monsoon. Besides, cultivation is fully depended on monsoon with poor management package of practice. Therefore, productivity of rice is considerably low in these states.

7. About 15% area of the total area under rice in the country is subjected to flooding particularly in Eastern Uttar Pradesh, Bihar, West Bengal, Orissa, Assam, Tripura and Manipur during south-west monsoon period. Intensity of floods differ from year to year due to variation in factors such as nature and frequency of flooding, water depth, turbidity, silt and vegetation from place to place. Such factors make the productivity of deep rice low.

8. The cultivation of rice under upland conditions is subjected to different degrees of moisture stress, which affects plant growth (height), tillering capacity less leaf area, higher sterility, delayed flowering and lower harvest ratio (grain-straw ratio). These factors or combination of these contribute lower grain yield in upland rice areas.

9. Upland rice fields are always infested with high degree of weed population which compete for water, nutrients and light than low land and fields. Therefore, the productivity of upland rice is affected considerably.

10. In Eastern states rice is grown mostly during Kharif season and it often suffers due to high rainfall. Besides, rice crop gets inundated during early part of the crop growth stage, low light intensity due to clouds for a longer duration resulting in higher sterility and pests/diseases. Therefore, productivity of rice is considerably low.

11. Due to non-availability of seeds location specific high yielding varieties, the farmers are forced to use local traditional varieties continuously due to lack of awareness about high yielding varieties.

12. Poor crop plant population in case of broadcast sowing method resulting in uneven germination (upland and direct seeded lowland). Delay in monsoon onset often results in delayed and prolonged transplanting and sub-optimum plant population (mostly in rainfed low lands). Therefore, the productivity is low.

13. Non-availability of bullock drawn/power drawn transplanter for timely transplanting of rice crop.

14. In the high rainfed regions, the rain water is lost rapidly through deep percolation, because of the upland location and loose texture of the soil. In these soils the plant nutrient applied through fertilizers are lost rapidly and investment of fertilizer become risky. Further, low water retention capacity by the soil due to high permeability brings in moisture stress conditions quickly after cessation of rains. Such situation contributes low productivity.

15. In the low rainfall regions , the crops suffer from iron and zinc deficiency in some soils. In the high rainfall regions diseases break out particularly Helminthosporium possibly due to imbalance nutrients availability in the soils.