EFFECTS OF MINERAL NITROGEN LEVELS AND FOLIAR NUTRITION ON GRAIN FILLING AND KERNEL WEIGHT OF “ISKANDAR” RICE
Keywords:
rice, grain filling, spikelet sterility, 1000-grain weight, nitrogen rate, foliar nutrition, biostimulant, Andijan.Abstract
This study evaluated grain filling, spikelet sterility, and 1000-grain weight of “Iskandar” rice under three mineral nitrogen levels and foliar nutrition treatments in the Andijan region of Uzbekistan during 2023-2025. The experiment comprised 21 variants arranged within N50, N100, and N150 kg ha⁻¹ backgrounds with a constant P120K100 kg ha⁻¹ supply. Fitovak, urea, YieldOn, and their combinations were applied at tillering and stem elongation. At N100P120K100, the three-year mean proportion of filled grains increased from 83.33% in the control to 89.97% under Fitovak + urea + YieldOn, while unfilled grains declined from 16.67% to 10.03%. The corresponding 1000-grain weight rose from 39.03 to 43.03 g. The biological maximum was obtained at N150 with the three-component treatment, which produced 90.47% filled grains and a 1000-grain weight of 44.03 g. Nevertheless, the N100 combination achieved nearly the same filling level with 50 kg ha⁻¹ less nitrogen. Because replication-level variance was unavailable, the results are interpreted descriptively and require confirmatory statistical testing.
References
1. Yoshida S. Fundamentals of Rice Crop Science. Los Baños: International Rice Research Institute, 1981. 269 p.
2. De Datta S.K. Principles and Practices of Rice Production. New York: John Wiley & Sons, 1981. 618 p.
3. Dobermann A., Fairhurst T. Rice: Nutrient Disorders and Nutrient Management. Singapore and Los Baños: PPI, PPIC and IRRI, 2000. 191 p.
4. Fageria N.K. The Use of Nutrients in Crop Plants. Boca Raton: CRC Press, 2009. 448 p.
5. Cassman K.G., Gines G.C., Dizon M.A., Samson M.I., Alcantara J.M. Nitrogen-use efficiency in tropical lowland rice systems: contributions from indigenous and applied nitrogen. Field Crops Research, 1996, 47: 1-12.
6. Peng X.L., Liu Y.Y., Luo S.G., Fan L.C., Song T.X., Guo Y.W. Effects of site-specific nitrogen management on yield and dry matter accumulation of rice from cold areas of Northeastern China. Agricultural Sciences in China, 2007, 6: 715-723.
7. Zheng Y.M., Ding Y.F., Liu Z.H., Wang S.H. Effects of panicle nitrogen fertilization on non-structural carbohydrate and grain filling in indica rice. Agricultural Sciences in China, 2010, 9: 1630-1640.
8. Tian G., Gao L., Kong Y., Hu X., Xie K., Zhang R. et al. Improving rice population productivity by reducing nitrogen rate and increasing plant density. PLoS ONE, 2017, 12(8): e0182310.
9. Hou W., Khan M.R., Zhang J., Lu J., Ren T., Cong R. et al. Nitrogen rate and plant density interaction enhances radiation interception, yield and nitrogen use efficiency of mechanically transplanted rice. Agriculture, Ecosystems and Environment, 2019, 269: 183-192.
10. Mahmoodi B., Moballeghi M., Eftekhari A., Neshaie-Mogadam M. Effects of foliar application of liquid fertilizer on agronomical and physiological traits of rice. Acta Agrobotanica, 2020, 73(3): 7332.
11. Su Z.F., Du Y.L., Zhou P.N., Sun C.M., Zhang Y.J., Ji C.M., Xu L.X. Effects of nitrogen fertilizer rate and planting density on leaf area and photosynthetic productivity of high-yield rice population. Chinese Journal of Rice Science, 2013: 38-41.
12. Wang S.L., Lin W.X., Liang Y.Y., Yu G.J. Effects of nitrogen fertilizer and plant density on culm quality, yield structure and nitrogen use in rice. Chinese Journal of Rice Science, 2009: 135-141.
