Regulation of plant Na/K ratio for productivity enhancement in Pokkali rice

Emily Alias, Deepa Thomas, Meera V. Menon, P. Prameela, A.K. Sreelatha


Pokkali is a unique rice farming system in coastal saline soils of Kerala. High Na content and the resultant wide ratio between Na and other cations, especially K, within the plant become detrimental for rice crop in these soils. An experiment was conducted at Rice Research Station, Vyttila during kharif 2018 to study the effect of liming and foliar application of K in reducing the Na/K ratio in Pokkali rice, adopting Randomised Block Design with 10 treatments replicated thrice and saline tolerant rice variety Vyttila 8. Treatments included two levels of lime (500 and 1000 kg ha-1) or dolomite (800 and 1600 kg ha-1) alone, and in combination, with foliar spray of sulphate of potash (SOP), 2% at 20 and 40 days after transplanting (DAT), foliar spray of SOP alone and control. The study indicated that application of lime at higher quantity, and foliar spray of SOP had significant influence on reducing the plant Na/K ratio. Number of tillers and panicles per m2, percentage of filled grain and grain yield were found to be higher on lime application @1000 kg ha-1 in combination with foliar spray of SOP, thereby enhancing the economic returns. Correlation analysis showed that grain yield and number of panicles had significant negative correlation with Na/K ratio at flowering. It was observed that flowering stage was the most critical one for maintaining a low Na/K ratio, which could influence the crop yield significantly.


Acidity, plant Na/K ratio, Pokkali rice, Salinity

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Ali, A., Salim, M., Zia, M.S., Mahmood, I.A. and Shahzad, A. 2005. Performance of rice as affected by foliar application of different K fertilizer sources. Pakist. J. Agric. Sci. 42(1-2): 38-41.

Ashraf, M., Shahzad, S.M., Imtiaz, M., Rizwan, M.S. and Iqbal, M.M. 2017. Ameliorative effects of potassium nutrition on yield and fiber quality characteristics of cotton (Gossypium hirsutum L.) under NaCl stress. J. Soil Environ. 36(1):51-58.

Bohra, J.S. and Doerffling, K.1993. Potassium nutrition of rice (Oryza sativa L.) varieties under NaCl salinity. J. Plant Soil 152(2): 299-303.

Fageria, N.K. and Knupp, A.M. 2014. Influence of lime and gypsum on growth and yield of upland rice and changes in soil chemical properties. J. plant nutr. 37(8): 1157-1170.

Munns, R. 2002. Comparative physiology of salt and water stress. Plant Cell Environ. 25(2): 239-250.

Nair, K. C., Sasidharan, N. K., Shylaraj, K. S. and George, K. M. 1993. Foliar spraying of K in rice in coastal saline soils. Int. Rice Res. Notes 18(2): 21-29.

Shylaraj. K.S., Sreekumaran, V., and Annie, K.2013.Five decades of glorious research at the Rice Research Station Vyttila (1958-2013). Directorate of extension, Kerala Agricultural University, Thrissur, 80p.

Sultana, N., Ikeda, T. and Kashem, M.A. 2001. Effect of foliar spray of nutrient solutions on photosynthesis, dry matter accumulation and yield in seawater-stressed rice. J. Environ. Exp. Bot. 46(2): 129-140.

Suriyagoda, L.D.B., Sirisena, D.N., Somaweera, K.A.T.N., Dissanayake, A., De Costa, W.A.J.M. and Lambers, H. 2017. Incorporation of dolomite reduces iron toxicity, enhances growth and yield, and improves phosphorus and potassium nutrition in lowland rice (Oryza sativa L). J. Plant Soil 410(1-2): 299-312.

Zhang, J. L., Flowers, T. J. and Wang, S. M. 2010: Mechanisms of sodium uptake by roots of higher plants. Plant Soil 326: 45-60.


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