~ 1747 ~ International Journal of Chemical Studies 2020; 8(3): 1747-1750 P-ISSN: 2349–8528 E-ISSN: 2321–4902 www.chemijournal.com IJCS 2020; 8(3): 1747-1750 © 2020 IJCS Received: 10-03-2020 Accepted: 12-04-2020 Sweta Singh Department of Soil Science and Agricultural Chemistry, IGKV, Raipur, Chhattisgarh, India Dr. Sangita Mohanty Scientist, Soil Science and Microbiology Crop Production Division, National Rice Research Institute, Cuttack, Odisha, India Dr. Rakesh Banwasi Scientist, Department of Soil Science and Agricultural Chemistry, IGKV, Raipur, Chhattisgarh, India Bhuneshwar Verma Department of Soil Science and Agricultural Chemistry, IGKV, Raipur, Chhattisgarh, India Corresponding Author: Sweta Singh Department of Soil Science and Agricultural Chemistry, IGKV, Raipur, Chhattisgarh, India Effect of different nitrogen levels on crop growth of various rice cultivars Sweta Singh, Dr. Sangita Mohanty, Dr. Rakesh Banwasi and Bhuneshwar Verma DOI: https://doi.org/10.22271/chemi.2020.v8.i3x.9449 Abstract An experiment were done to analyze the effect of different nitrogen levels on crop growth of various rice cultivars with different rice varieties. Six cultivars from rice (Naveen, Indira, Ratna, Surendra, Birupa and Daya) were evaluated in the kharif season 2017-2018. The experiment were conducted in factorial randomized block design with three replications. Among the cultivars of rice, the effect of nitrogen levels on crop growth rate found to be proportional till the vegetative stage and then diminishing effect on crop growth rate is observed during reproductive stage. The highest CGR was observed in naveen and birupa and lowest in daya and surendra. Keywords: Crop growth rate (CGR), nitrogen (N), maximum tillering (MT), panicle initiation (PI), flowering (FL), grain filling (GF) and maturity Introduction Nitrogen (N) is the most important essential element for the overall growth and development of plants. Despite its high abundance in the air (around 79%), it is not readily available for them; rather, it is added mostly as inorganic fertilizer in the agricultural lands. Globally, 50% of human population relies on nitrogen (N) fertilizer for food production (Smil 2001) [12] . The N fertilizer consumption has grown dramatically in Asia, about 17-fold in the last 40 years (Ali et al. 1999; Dobermann and Cassman 2004; Rahn et al. 2009) [2] . However, it is remarkable that only 50% or less of the applied nitrogen is used for the production of the aboveground biomass of cereals. Optimum nutrient management has long been acknowledged as being critical for producing high yield in rice. Unless the supply of fertilizer nutrients to the crop is increased, low availability will remain as a serious constraint to increase rice production. Temperature, solar irradiance, and water are the important biophysical factors controlling crop growth and crop demand for N and hence NUE. Farmers cannot control temperature and solar irradiance. Water also remains outside their control, unless the infrastructure for irrigation is in place. The predictability of these three plant growth factors largely depends on the climatic region where the crop is grown. Following solar irradiance, temperature, and water, inadequate availability of nutrients, particularly N, is the next plant growth limiting factor. High yielding crops require large amounts of nutrients, which have to be supplied as inorganic or organic amendments. Irrigation and fertilization are thus the most effective means of increasing crop yields at many sites (Norwood, 2000) [8] . Agronomic practices such as applying N at the right time, in the right amount, and at the right place will improve crop health and reduce pest incidence. Crop cultivars also differ in their ability to acquire N from the soil in producing yield per unit of N acquired. Nitrogen accumulation or uptake in different plant parts, as well as in the whole plant, during different phases of growth, clearly indicate higher nitrogen accumulation in stems and leaves during vegetative phase. Hence, nitrogen accumulation in different organs and in the whole plant follows a parabolic pattern during the ontogenic development of the plant (Basuchaudhuri, 2016). It is evident that nitrogen concentrations in different plant parts decrease with ageing. However, a sharp decline in nutrient concentrations in leaves and stem was noted during