Pakistan Journal of Nutrition 11 (7): 531-536, 2012 ISSN 1680-5194 © Asian Network for Scientific Information, 2012 Corresponding Author: Javaid Iqbal, College of Agriculture, Dera Ghazi Khan 32200, Punjab, Pakistan 531 Effect of Seeding Rates and Nitrogen Levels on Yield and Yield Components of Wheat (Triticum aestivum L.) Javaid Iqbal , Khizer Hayat , Safdar Hussain , 1 1 1 Anser Ali and Muhammad Ahmad Alias Haji Ahmad Bakhsh 1 2 College of Agriculture, Dera Ghazi Khan 32200, Punjab, Pakistan 1 Agriculture Adaptive Research Complex, Dera Ghazi Khan, Pakistan 2 Abstract: A field experiment to investigate the effect of seeding rates and different levels of nitrogen on yield and yield components of wheat was conducted at Research Area, College of Agriculture, Dera Ghazi Khan. An approved cultivar Fareed-2006 was sown at seeding rates of 125, 150 and 175 kg/ha with five nitrogen levels of 0, 75, 100, 125 and 150 kg N/ha. Experiment was laid out in Randomized Complete Block Design (RCBD) with split plot arrangement keeping seed rate in main plots and nitrogen levels in sub plots having three replications while, net plot size was 3 x 7 m . Yield components such as plant height (cm), spike length 2 (cm), number of spikelets/spike, number of grain/spike, 1000-grain weight (g), biological yield (kg/ha), grain yield (kg/ha) and harvest index were maximum at seeding rate of 150 kg/ha and minimum at seeding rate of 125kg/ha while number of tillers were maximum at seeding rate of 175 kg/ha and minimum at seeding rate of 125kg/ha. Similarly plant height, number of tillers m , spike length, number of spikelets/spike, number -2 of grain/spike, 1000-grain weight, grain yield, biological yield and harvest index were highest at nitrogen at 125 kg/ha and lowest at zero level of nitrogen. The interaction between seeding rates and nitrogen levels was found non significant for plant height, number of tillers m spike length, number of spikelets/spike and 1000 -2 grain weight while a significant interaction was noted for number of grain/ spike, grain yield, biological yield and harvest index and were maximum at seeding rate of 150 kg/ha with nitrogen level of 125 kg/ha. Key words: Seed rate, wheat, nitrogen, yield components INTRODUCTION Agriculture sector being the important component of the country’s economy and continues to be the single largest sector that is acting as a dominant driving for growth and development of the national economy. Since the time of independence Pakistan has been trying its best to provide the basic requirements of its people through sufficient wheat production. Although wheat production of Pakistan is increasing sufficiently but the average per acre yield in Pakistan (2639 kg/ha; Govt. of Pakistan, 2010) is far below than the world’s average and that of developed countries of the world such as Germany (7282 kg/ha), Egypt (6251 kg/ha), Mexico (4404 kg/ha) and China (3729 kg/ha) (FAO, 2002). Even with in the country there is much difference in yield gap in average (2639 kg/ha) as compared to the potential (7200 kg/ha) of our existing wheat varieties. It is desired to have higher yield per unit area to meet the increasing demand of food grain for rapidly growing population of the country. The main factors responsible for low yield are less or more plant population and inadequate crop nutrition. Plant density is a major factor determining the ability of the crop to capture resources and generate yield. It can be developed by using a suitable seeding rate. Growth and yield of wheat are affected by environmental conditions and can be regulated by sowing time and seeding rate (Ozturk et al., 2005). Maximum genetic potential of high yielding wheat varieties cannot be harvested without ensuring proper seeding rate. It is of particular importance in wheat production because it is under the farmers control in most cropping systems (Satorre, 1999). Consequently, there is value in defining relationships between density, tiller production and wheat yield to establish optimum seeding rates for various regions (Anderson and Sawkins, 1997). As the plant density increases, the competition for resources especially for nitrogen also increases that badly affect the ultimate yield. Provision of additional nitrogen can be hypothesized to further enhance the yield by increasing plant population but up to an optimum level. Further higher nitrogen can lead to the lodging of plants at higher seed rate (Nazir et al., 2000). Nitrogen occupies a conspicuous place in plant metabolism. All vital processes in plant are associated with protein, of which nitrogen is an essential constituent. Consequently to get more crop production, nitrogen availability is essential in the form of chemical fertilizers. Proper use of nitrogen is also considered for farm profitability and environment protection (Makowski