*Corresponding author, E-mail: ysshivay@hotmail.com 290 Indian J. Plant Physiol., Vol. 14, No. 3, (N.S.) pp. 290-298 (July-Sept., 2009) EFFECT OF NITROGEN SOURCES, SULPHUR AND BORON ON GROWTH PARAMETERS AND PRODUCTIVITY OF SPRING SUNFLOWER KAPILA SHEKHAWAT AND YASHBIR SINGH SHIVAY* Division of Agronomy, Indian Agricultural Research Institute, New Delhi-110 012 Received on 24 July, 2008, Revised on 14 Sept., 2009 SUMMARY A field experiment was conducted during spring seasons of 2005 and 2006 on a sandy loam soil at the research farm of the Division of Agronomy, Indian Agricultural Research Institute, New Delhi to study the effect of different nitrogen sources, sulphur and boron on growth, physiological parameters and productivity of spring sunflower (Helianthus annuus L.). The effect of the two sources of nitrogen, i.e. prilled urea (PU) and calcium ammonium nitrate (CAN) on various growth parameters of spring sunflower like leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR) and net assimilation ratio (NAR) were remained statistically on par with each other. However, the application of higher doses of sulphur (50 kg sulphur/ha) and boron (1.5 kg boron/ha) enhanced significantly all the growth parameters. LAI increased substantially between 50-75 days after sowing (DAS) and the highest values were recorded at 75 DAS. Application of the nutrients increased the dry matter accumulation of the crop plant and hence, other growth indices like CGR, RGR and NAR also increased significantly. The crop achieved the highest CGR in between 50-75 DAS while the RGR and NAR values were recorded highest at the initial crop growth stages and declined thereafter. The highest seed yield (2 011.9 & 2 001.9 kg/ha in 2005 and 2006 respectively) and total biological yield (4 207.1 & 4 177.4 kg/ha in 2005 and 2006, respectively) were obtained with application of 1.5 kg B/ha, S application also showed a significant effect on seed and biological yields. Harvest index (HI) was not influenced significantly due to above fertilization. Key words: Boron, growth parameters, nitrogen, productivity, sulphur, sunflower very low because of the existed sub-optimal soil fertility conditions. Nitrogen supply strongly influences the crop growth through its effect on leaf area development and photosynthetic capacity (Tenebe et al. 1996, Tonev 2006). Ammonium (NH 4 + ) and nitrate (NO 3 - ) are the two sources of nitrogen supply, which influences crop growth, especially at the initial crop growth stage. Calcium ammonium nitrate is supposed to be a better source as it alters sugar metabolism and certain physiological phenomena. Sunflower is considered as a heavy feeder of nutrients, particularly sulphur, being an oilseed crop. Sulphur deficiency at vegetative growth stage cause Indian J. Plant Physiol. , Vol. 14, No. 3, (N.S.) pp. 290-298 (July-Sept., 2009) INTRODUCTION India has the fourth largest oilseed economy in the world, yet 40% of the edible oils available in India are imported to meet out their daily cooking requirement. Sunflower (Helianthus annuus L.) can help to meet out this shortage of edible oils due to its rich oil content, (up to 50%). It is photo-thermo insensitive and has wide adaptability under different agro-climatic regions, especially spring sunflower, as it can be grown when the field is otherwise fallow. It is the fourth most important oilseed crop of India, but the yield levels are