Effects of Nitrogen Aerosols on Biochemical Traits of Some Kharif Rice (Oryza sativa L.) Genotypes

Nitrogen is indispensable for plant growth, as it makes up 1 to 4% of the dry matter of the plants. In proteins and nucleic acids, it is a major component. It acts as an essential constituent of chlorophyll and many other enzymes (Leghari et al., 2016). Therefore, the availability of nitrogen insufficient quantity throughout the growing season is essential for optimum growth and production of crop plant. There is also importance of nitrogen to maintain its correct ratio (12:1 to 15:1) with sulphur in improving yield and quality of crops (Klikocka and Marks, 2018). In order to increase crop production, approximately 107.55 million metric tons of N fertilizers were applied globally in 2019 (Statista, 2022). Approx. 80 million tones of the total N fertilizer is utilized for cereals globally (FAO, 2014). Generally, only 40–50% of the applied N fertilizer is utilized by the crop (Sylvester-Bradley and Kindred, 2009). Leaching, runoff, volatilization, and denitrification are major causes of nitrogen losses in the environment. Nitrogen which is lost from the plant–soil system can result in environmental problems, including water and air pollution (Sainju, 2017). Dissolved N in groundwater mostly in the form of NO-1 and NH +are leached out or lost 3 4 through gaseous emissions of nitrous oxide and ammonia (Neill et al., 2005). Janzen and Ellert (1998) observed that nitrogen is lost by the denitrification mechanism from agricultural soils. Neill et al. (2005) reported a loss of 20–40% of theN applied in the soil. In general, Urea or Diammonium phosphate (DAP) is used at basal and maximum tillering stages of rice crop, which is prone to the environmental losses. Apart from these forms of synthetic N, knowledge on fertilizing crops with N-aerosols is lacking. Because, N may be received from the atmosphere as a consequence of lightening or dry and wet deposition of Non foliage at physiological pH. In this context, the responses of kharif rice genotypes to nitrate and ammonium forms of nitrogen aerosols are poorly understood.

A stable suspension of solid and liquid particles in a gas is known as aerosols. Aerosol particle size varies in between 0.001 to 100µm (Colbeck and Lazaridis, 2010). Nitrogen oxides (NO ) viz., NO and NO , and N O are major atmospheric pollutants in X 2 2 rapidly growing urban and its surrounding areas of Assam (Bharali et al., 2012). The NOx emitted in the form of nitric oxide (NO), reacts rapidly in the atmosphere and in a complex cycle with light, ozone, hydrocarbons, and produces nitric acid. These materials interact with plants and soil locally or transported from the site to react with atmospheric particulates to form aerosols. These aerosols comeback to fertilize terrestrial and aquatic systems in the form of wet and dry deposition. It was estimated that about 5% of the total anthropogenic greenhouse effect is credited toN O form, which is 70% of annual global 2 anthropogenic emissions come from animals and crop production (Arvind, 2001). There is the possibility of nitrogen nutrition in rice by foliar feeding with N-aerosols (salts of nitrogen) instead of soil application (Bharali et al., 2017). Therefore, an investigation into effects of N-aerosols on biochemical traits of rice crop especially NUE in rice crop was undertaken.