Acta Hortic. 1255. ISHS 2019. DOI 10.17660/ActaHortic.2019.1255.16 Proc. Int. Symp. on Horticulture: Priorities and Emerging Trends Eds.: M.R. Dinesh et al. 97 Chitosan-urea nano-formulation: synthesis, characterization and impact on tuber yield of potato A. Kalia 1,a , Rohini 2 , K. Luthra 2 , S.P. Sharma 3 , G. Singh Dheri 4 , M. Sachdeva Taggar 5 and C. Gomes 6 1 EMN Laboratory, Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab, 141004, India; 2 Department of Microbiology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India; 3 Department of Vegetable Science, Punjab Agricultural University, Ludhiana, Punjab, 141004, India; 4 Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab, 141004, India; 5 School of Renewable Energy Engineering, Punjab Agricultural University, Ludhiana, Punjab, 141004, India; 6 Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA. Abstract Conventional mineral N-fertilizers suffer from greater losses and have attendant negative impacts on environment. The agronomic and economic loss of applied N- fertilizers particularly ‘urea’ accounts for low use efficiency. Potato (Solanum tuberosum L.), the third important food crop after rice and wheat considering total global production, is one among the most N-responsive crops. However, the shallow root system and poor uptake efficiency compounds the low NUE in this major non-grain food crop. The ‘nano-N fertilizers’ can enhance potato productivity besides mitigating N-losses and perhaps fertilizer application rates. The present study investigated the effect of application of degradable polymer encapsulated urea fertilizer on soil enzyme activity and yield and component traits of potato cultivar ‘Pukhraj’. Nanoencapsulation of five different concentrations of granular urea (3, 7, 10, 30 and 50% w/v) in chitosan (1.5% w/v) hydrogel through ionotropic gelation resulted in formation of spherical nano-chitosan-urea particles varying in size from 75 to 250 nm. The nanoparticle sizes varied in accordance to the concentration of the supplemented urea. Likewise, the functional group characterization by FT-IR spectroscopy showed increase in amide peak intensity with increase in urea concentration. A pot study performed using four urea/nano-urea application rates (0, 50, 75 and 100% RDF) enhanced soil dehydrogenase activity, root length, tuber size and yield of potato cultivar ‘Kufri Pukhraj’ in chitosan-urea treatment. This study showed potential of encapsulation of urea in chitosan polymer and its beneficial effects for enhancing yield in potato. Keywords: biodegradable polymer, electron microscopy, FT-IR spectroscopy, nanoencapsulation, nitrogen INTRODUCTION World’s agricultural cropping systems are utilizing a large amount of inorganic synthetic fertilizers to obtain higher yields per unit area (Timilsena et al., 2015; Heffer and Prudhomme, 2015). This has often led to over-application of conventional fertilizers leading to serious ecological implications (Chen et al., 2008). The application of conventional N- fertilizer, ‘urea’, has been associated with losses in biosphere in gaseous form as ammonia and nitrous oxides (Macdonald et al., 2014), and leaching as nitrates leading to contamination of the ground water aquifers (Burkitt, 2014). Urea exhibits substantially low use efficiency (Rose, 2016), besides excessive application of urea it can cause damage to the soil structure, mineral cycles, associated soil micro-flora, and toxic nitrate accumulation in plants. Therefore, certain alternative slow and continuous release formulations of the conventional urea fertilizer need to be developed for crops exhibiting high N-requirements (Rose, 2016). Potato, the third important food crop after wheat and rice, is one among the most N- demanding and N-responsive crops (Gálvez et al., 2016). India ranks third in area and fourth (26.28 million t) in total potato production of the world (Horticulture Statistics 2015, India). a E-mail: kaliaanu@pau.edu