Agronomical efficiency of two Wheat (Triticum aestivum L.) Varieties against different level of Nitrogen fertilizer in Subtropical region of Pakistan

Wheat (Triticum aestivum L.), cultivated worldwide is the principal source of human diet with prominent position among cereals [1] particularly in the Asia and more specifically in the south Asian region supplying 68 percent of the calories and protein in the diet [2].Wheat flour is used for leavened, flat and steamed breads as well as most of the baked products [3]. The daily diet of people in Pakistanis mainly based on wheat [4].Importance of wheat in Pakistan can be noted from the fact that agricultural policies are formulated focusing this crop; 60 percent of daily diet of common man is based on wheat with average per capita consumption of 125 kg [5].

Pakistanis known to be the most important country where wheat is cultivated extensively in its all ecological conditions and included in world top ten wheat producing countries [6] but the average yields are much lower than other major wheat growing countries including China, USA, and India etc. [7]. Wheat is the leading food grain of Pakistan and occupies the largest area under single crop and contributes 10.0 percent to the value added in agriculture and 2.1 percent to GDP. Area under wheat has decreased to 9180 thousand hectares in 2014-15 from last year’sarea of 9199 thousand hectares which shows a decrease of 0.2 percent. The production of wheat stood at 25.478 million tons during 2014-15, showing a decrease of 1.9 percent over the last year’sproduction of 25.979 million tons [8].Grain yield per unit area of wheat achieved in the country is still far less than the advanced wheat growing countries of the world. The low yield is attributable to many factors that include various agronomic factors [9] such as improper inputs application [10, 11]. Besides its tremendous significance, average yield is far below than developed countries [12]. Nutrient deficiency is one of the important factors. The universal deficiency of N has become more severe in regions of continuous cropping [13]. Nitrogen is essential element of bio-molecules (amino acids, proteins, nucleic acids, phytohormones and enzymes and coenzymes). N stimulates growth, expands crop canopy and interception solar radiation [14].Plants are surrounded by theN in atmosphere; and every acre of the earth’ssurface is covered by thousands of pounds of nitrogen [15].Varieties and fertilizers are two dominant factors which greatly influence the yield. Introduction of new wheat varieties has not only raised the production, but also the standard of downtrodden farmers. New varieties are more responsive to fertilizer than older ones and resistant to lodging. Nitrogen plays an important role in boosting up the yield when used in an appropriate amount. The studies carried out earlier indicated that highest wheat grain yield (4293 kg ha-1) was recorded with application of 150 kg N ha-1[16, 17]. A linear increase in wheat grain and straw yield with additive dose of N fertilizer up to 120 kg N ha-1[18].The high wheat yield can sustainably be achieved with application of N fertilizer in addition toP and Kat optimum rates. The recommended dose 120kg P ha-1 for achieving higher grain yield, nutrient uptake, spike number and grains spike-1[19]. The highest wheat yields when the crop was fertilized with 90 kg of N ha-1. The use of mineral fertilizers is beneficial for increasing the soil fertilizer status and crop productivity and 80-120 kg N ha-1 fertilization in wheat for achieving higher yields [20]. Nitrogen upto 180 kg ha-1 in addition to P,at 120 kg ha-1 for achieving higher yields indifferent wheat varieties [21]. Recommended dose of 200 kg N ha-1 compared to dose of 150 kg N ha-1 for increased grain yield [22]. Nitrogen at the rate of 200 kg ha-1 resulted in maximum crop performance for height of plants, leaves plant-1,tillers, earhead length, matter yield, grains earhead-1, spikelets earhead-1and biological yield [23]. In view of the facts stated above, the experiment was performed to identify the optimum nitrogen requirement of two wheat varieties under agro-ecological conditions of Tandojamto assess the growth and yield response of different wheat varieties to different levels of nitrogen and to find out wheat variety with enhanced yield potential and optimum Nitrogen use.