Physiological, Phenological and Yield Responses of Rabi Sunflower and Mustard under Conventional Urea and Foliar Nano-urea Nitrogen Management
Gouraram Manoj Kumar Goud *
Department of Agronomy, College of Agriculture, Professor Jayashankar Telangana Agriculture University, Rajendranagar, Hyderabad, Telangana, India.
Kasbe Sudhanshu Sudhakar
Department of Agronomy, Agricultural College, Adilabad, Professor Jayashankar Telangana Agriculture University, Telangana, India.
Md. Latheef Pasha
College of Agriculture, Professor Jayashankar Telangana Agriculture University, Rajendranagar, Hyderabad, Telangana, India.
A. Madhavi
Professor Jayashankar Telangana Agriculture University, Rajendranagar, Hyderabad, Telangana, India.
Santanu Kundu
ICAR-Indian Agricultural Research Institute, New Delhi, India.
K. Ramakrishna
Department of Agronomy, College of Agriculture, Professor Jayashankar Telangana Agriculture University, Rajendranagar, Hyderabad, Telangana, India.
*Author to whom correspondence should be addressed.
Abstract
Efficient nitrogen management is essential for improving the productivity of oilseed crops such as sunflower (Helianthus annuus L.) and mustard (Brassica juncea L.). Foliar nano-urea offers a potential approach to supplement conventional nitrogen fertilisation; however, its effects on physiological traits, flowering behaviour, oil content and seed yield in rabi sunflower and mustard under Telangana conditions remain insufficiently understood. The present study was carried out during rabi 2021–22 at the Agricultural Research Institute, PJTSAU, Rajendranagar, Hyderabad, to evaluate the effect of foliar application of nano-urea on SPAD, GreenSeeker-derived NDVI, days to 50% flowering, oil content and seed yield of rabi sunflower (Helianthus annuus L.) and mustard (Brassica juncea L.). The experiments were laid out in randomized block designs with three replications. In sunflower, 50% RDN was applied at sowing followed by foliar application of nano-N at 2, 2.5, 3, 3.5 and 4 mL L⁻¹ at the star-bud and 50% flowering stages, while in mustard, 50% RDN was applied at sowing followed by nano-N sprays at the rosette and flowering stages. In sunflower, conventional split application of nitrogen produced the highest SPAD value (35.0) at 50% flowering and GreenSeeker NDVI (0.75), compared with 32.3 SPAD and 0.64 NDVI with nano-N @ 4 mL L⁻¹. Conventional nitrogen application also resulted in earlier 50% flowering (55.3 days) and the highest seed yield (1774 kg ha⁻¹) and oil content (43.0%). Although foliar nano-N treatments improved seed yield over the no-N treatment, they remained inferior to conventional nitrogen application. In mustard, 50% RDN at sowing + nano-N @ 4 mL L⁻¹ at rosette and flowering recorded the highest SPAD (34.0) and GreenSeeker NDVI (0.52), with 50% flowering at 45 days, the highest seed yield (1126 kg ha⁻¹) and an oil content of 34.5%. The seed yield was comparable with the recommended conventional nitrogen treatment (975 kg ha⁻¹). Overall, the results suggest that SPAD and GreenSeeker NDVI effectively reflected crop nitrogen status and were associated with differences in flowering and yield performance. Foliar nano-urea showed greater potential as a partial substitute for conventional nitrogen in mustard than in sunflower.
Keywords: Nano-urea, foliar application, nitrogen management, SPAD, Green-Seeker, NDVI, phenology, seed yield, sunflower, mustard