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2. Introduction N deficiency is common in all rice-growing soils where modern varieties are grown without sufficient mineral N fertilizer. Significant yield responses to N applied in mineral and/or organic forms are obtained in nearly all lowland rice soils where irrigation and other nutrients and pests are not limiting. Sufficient N supply during ripening is necessary to delay leaf senescence, maintain photosynthesis during grain filling, and increase protein content in the grain. End Next

3. Role of Nitrogen in rice Essential constituent of amino acids, nucleic acids, nucleotides, and chlorophyll, etc. It promotes faster growth, especially increased plant height and tiller number. Nitrogen Increases leaf size of rice. It enhances spikelet number per panicle, percentage of filled spikelets in each panicle. N increases protein content in rice grain. Nitrogen drives the demand for other macronutrients such as phosphorus and potassium. End Previous Next

4. It is important to note that: The demand for nitrogen is between the early to mid-tillering and panicle initiation stages is relatively higher. Adequate N supply during ripening is must be maintained to delay leaf senescence (maturity), maintain photosynthesis during grain filling, and increase protein content in the grain. Being a mobile nutrient in plant, N moves within the plant and, because N is translocated from old senescent leaves to younger leaves, deficiency symptoms tend to occur initially in older leaves. End Previous Next

5. N deficiency symptoms Reduced growth and plants become yellowish in colour. In the beginning the deficiency symptoms first appear on lower (older) leaves and afterwards the whole plant becomes yellowish green. Death of leaves may occur under severe N deficiency. Affected leaves are narrow, short, erect, and lemon-yellowish green. In some cases the entire field may appear yellowish. End Previous Next

6. N deficiency symptoms N deficiency is more prominent at critical growth stages such as tillering and panicle initiation when the demand for N is high. N deficiency causes reduction in tillering, leaf size, plant height and filled grains number in rice. Sometimes, the visual symptoms of N deficiency can be confused with those of S deficiency, but S deficiency tends to first appear on younger leaves or all leaves on the plant. Also, mild N deficiency can be confused with Fe deficiency, but the iron deficiency first appear on the emerging leaves. End Previous Next

7. Nitrogen deficiency in rice nursery End Previous Next

8. N deficiency in rice N deficiency The following link is also useful to know more about deficiency symptoms of different nutrients: http://www.laagcon.org/presentations/2008/RBSaichuk.pdf. End Previous Next

9. Excess of Nitrogen • Dark green foliage. Increased susceptibility to lodging and drought Increased disease incidence and insect invasion. In severe excess the crop may fail to yield grains. End Previous Next

10. Causes of N deficiency Soils are inherently low in organic matter (and hence, nitrogen), and have less N-supplying power. Simultaneously, inadequate use of mineral of N fertilizer or organic manures. Low use efficiency of nitrogenous fertilizers, especially due to volatilization, denitrification, leaching, and runoff, etc. Permanently submerged conditions that reduce indigenous soil N supply. Heavy rainfall may result in increased N loss by surface runoff, leaching and seepage. End Previous Next

11. Occurrence of N deficiency N deficiency may be common under the following soils: Soils having very low soil organic matter content (e.g., <0.5% organic C, coarse-textured acid soils). Soils which have constraints to supply indigenous nitrogen (e.g., acid sulphate soils, saline soils, P-deficient soils, poorly drained wetland soils where the amount of N mineralization or biological N2 fixation is small). • Alkaline and calcareous soils having very low soil organic matter content and a high potential for ammonia volatilization losses. • Intensive cropping without using adequate doses End Previous Next

12. Corrective measures (N) • Add organic manure/ green manures before transplanting / sowing of rice. • Use biofertilizers like Azotobacter • and Azospirillum ,etc. • Apply N fertilizers on the appearance of • deficiency symptoms. • Follow strictly the fertilization schedule recommended for rice, particularly suitable for the region. End Previous Next

13. Corrective measures (N) If legume crops are green-manured before rice transplanting, the rice crop would need 60 kg/ha less nitrogen through fertilizers or other manures Dhaincha Sannhemp Mungbean End Previous Next

14. Corrective measures (N) Apply the appropriate dose of nitrogenous fertilizers End Previous Next

15. Let us Sum up N is a part of the chlorophyll (the green pigment in leaves) and is an essential constituent of all proteins. N deficiency in plants results in a marked reduction in growth rate. N-deficient plants have a short and spindly appearance, poor tillering and reduced leaf. N The effects of N toxicity are less evident than those of its deficiency. Excess nitrogen results in prolonged growing (vegetative) period and delayed crop maturity. Intensive cropping systems with less input of nitrogen causes N deficiency in crops. N can be supplied through different organic sources, chemical fertilizers and biofertilizers. End