Integrated Nitrogen Management through Different Sources on Growth and Yield of Wheat ( Triticum aestivum L.)

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Wheat (Triticum aestivum L.) is the most strategic cereal crop in the world as well as in India and it is estimated that more than 35 per cent of the world population depends on wheat.Wheat is the second important staple food crop in India after rice.India, being the 2nd largest producer of wheat all over the world, next to china, produced around 12 per cent of world wheat production, covering an area of 29.04 million hectares with total production of 87.39 million tonnes with productivity of 3009 kg ha -1 .While, in Gujarat it is grown over an area of 1.35 million hectares with an annual production of 3.65 million tonnes with the productivity of 2730 kg ha -1 (Anon., 2015), which is lower compared to national productivity.The existing low yield level suggests the scope and need for increasing the productivity of wheat.
Fertilizer has been and will continue to be the key input for achieving the estimated food grain production goals of the country.The importance of nitrogen and phosphorus application to wheat crop has been recognized since long and is the backbone of any fertilizer management programme.Adequate nitrogen fertilization is a prerequisite to produce high yields of wheat and to improve the grain quality.Wheat is sensitive to nitrogen deficiency and very responsive to nitrogen fertilization.Adequate supply of nitrogen improves the yield components and ultimately increases the grain yield.However, the prolonged and injudicious use of fertilizers leads to human and soil health hazard along with environment pollution.In such situation organic sources of nitrogen improve the availability of mineral nutrients in the soil for plants (Ghafoor et al., 2015).For sustainable and high productivity of crops over prolong period, maintenance of soil organic matter at a satisfactory level is necessary.The FYM and vermicompost are the sources of primary, secondary and micro nutrients for plant and are constant sources of energy for hetrotrophic micro-organisms, which helps in increasing the availability of nutrients, quality and quantity of the crop produce.
Traditionally, nitrogen is applied through urea in the soil, which becomes inadequate for the farmer at sowing time.In such situation the foliar application of plant nutrient is effective and economical.Furthermore it has been observed that fertilizer efficiency particularly urea application through soil is not as effective as if it is applied to plants through foliage along with soil application, because only 20 to 50% of the soil applied nitrogen is recovered by annual crops.Even several researchers have shown that foliar nitrogen application has higher recovery rather than soil application (Bajwa, 1992).Khan et al., (2009) also reported that nitrogen is also taken up directly through wheat leaves when applied as a solution.Recently foliar fertilization is widely used practice to correct nutritional deficiencies in plants and has potential advantages over soil application and it may increase the efficacy of fertilizer use.Similarly, in terms of yield it is more efficient than soil fertilization for both macro and micronutrients in different soil types.(Ali et al., 2008, Alam et al., 2010).

MATERIALS AND METHODS
A field experiment was conducted during rabi season of 2016-17 at Agronomy Farm, B. A. College of agriculture, Anand Agricultural University, Anand to sstudy nitrogen management through different sources on growth and yield of wheat (Triticum aestivum L.) on loamy sand soil, having 0.38 % Organic Carbon by Walkley and Black method (Jackson, 1973), 231.50 kg ha -1 available N by Alkaline KMnO4 method (Subbiah and Asija, 1956) , 39.56 kg ha -1 available P 2 O 5 by Spectrophotometric method (Olsen et al., 1954) and 310.40 kg ha -1 available K 2 0 by Flame Photometric method (Jackson, 1973) with 8.02 pH by Potentiometric method (Jackson, 1973).
The harvest index for each treatment was worked out by using the following formula given by Donald and Hamblin (1976): The Benefit: Cost ratio (BCR) for each treatment as well as for treatment combinations was also calculated on the basis of formula given below:

Effect on growth parameters
A close proximity to the growth data furnished in table-1 revealed that initially at 30 DAS, plant height remained unaffected due to different treatments, but at later growth stages, treatment T 9 (75% RDN + 2% Urea spray at 30, 40 and 50 DAS), being at par with T 1 , T 3 , T 2 , T 4 and T 5 had significantly higher plant height (78.33 cm) at 60 DAS.However, at harvest, treatment T 3 (75% RDN + 25% N through VC) recorded significantly higher plant height (109.50 cm), though it was found at par with T 9 , T 4 , T 2 and T 1 .
An improvement in plant height could be attributed to the fact that nitrogen being an integral part of chlorophyll, a primary absorber of light energy needed for photosynthesis, is directly absorbed through stomata of plant leaves owing to foliar sprays with urea from time to time, which might be responsible for increase in stem length at boot stage due to increase cell division and multiplication.The favourable effect of organic sources viz; FYM or vermicompost on growth might be attributed to presence of relatively readily available plant nutrients, growth enhancing substances and number of beneficial organisms like nitrogen fixing, cellulose decomposing and other beneficial microbes as well as antibiotics, vitamins and hormones etc.Similar trend was observed by Dhillon et al., (1987), Patel et al., (1991) and Kumar et al., (2015).

Effect on yield and yield attributes
The data pertaining to yield attributes viz; are furnished in table-2.It was explicit from the results that treatment T 3 (75% RDN + 25% N through VC) recorded significantly higher number of total tillers (157.35) and effective tillers (151.53),however, treatments T 9, T 1 , T 2 and T 4 and T 9, T 2 and T 1 remained at par with T 3 for total and effective tillers, respectively.
Treatment T 9 (75% RDN + 2% Urea spray at 30, 40 and 50 DAS) had significantly higher number of spikelet spike -1 (55.70), which was statistically at par with T 3, T 1 T 4 and T 10 .Length of spike was also significantly influenced by the same treatment (T 9 ) having higher length of spike (10.53 cm) which was found identical with treatments T 4 , T 1 , T 3 , T 8 , T 2 and T 6 .Similarly, treatment T 9 (75% RDN + 2% Urea spray at 30, 40 and 50 DAS), being at par with treatment T 3 , T 1 and T 2 , recorded significantly higher number of grains spike -1 (53.48).Dry matter accumulation (g plant-1 ) at 45 DAS, was significantly influenced by different treatment.Treatment T 9 (75% RDN + 2% Urea spray at 30, 40 and 50 DAS) produced significantly higher dry matter accumulation per plant (10.58 g) , which was found identical with treatments T 3 and T 1 .In case of test weight (g) again treatment T 9 (75% RDN + 2% Urea spray at 30, 40 and 50 DAS) recorded significantly higher test weight (48.78 g), which was found statistically at par with treatments T 3 , T 1 and T 2 (44.07 g).
However, for straw yield of wheat (Table -3), treatment T 3 ( 75% RDN + 25% N through VC), being at par with treatments, T 9 , T 4 , T 1 and T 2 yielded significantly higher straw yield (8971 kg ha-1).Nitrogen management did not show significant influence on harvest index.
Since, yield of the crop is a function of several yield components, which are dependent on complementary interaction between vegetative and reproductive growth of the crop.It was noticed that a magnitude of variation in the grain yield was proportional to the variation in the yield attributing parameters like number of effective tillers, number of spike plant -1 , number of spikelet spike -1 , spike length, dry matter accumulation and test weight.Further, an increase in the grain yield with vermicompost or FYM application along with 75 % RDN might be due to the fact that added vermicompost or FYM served as store house of several macro and micronutrients which are released during the process of mineralization.This might be due to the fact that urea is mineralized within 7-8 days of application (Islam and Parsons, 1978), whereas vermicompost and FYM initiated their mineralization from 15 days of their application and lasted up to 30 days (Joy and Kamath, 2017).
Among the treatments, conjunctive use of soil application along with foliar spray of 2% urea at 30, 40 and 50 DAS recorded higher grain yield probably because of optimum supply of nutrients at right time of crop requirement and wheat responds well to fertilizer application as a result of its well-developed root system, crop absorbed required nutrients from soil for effective dry matter production and translocation of photosynthates from leaves to the sink for better development of grains.(Alston et al,1979).
The other difference in grain yield due to nitrogen levels was related to the difference in size of photosynthetic surface and to the relative efficiency of total sink activity, which in turn influenced the direction of movement of substrates.Parvez et al., (2009) advocated that, urea foliar spray has advantage to increase wheat grain yield over 25 per cent in soil moisture deficient areas.Similarly, foliar application of urea to wheat at tillering increased grain yield and grain protein content under soil moisture limiting conditions in the marginal area.

CONCLUSION
It could be concluded from the present investigation that higher grain yield, net realization and benefit cost ratio (BCR) of wheat could be achieved with 75% RDN (90 kg N ha -1 + 2% Urea spray at 30, 40 and 50 DAS) to curtail 16.2 kg N ha -1 .It is comparable with 75% RDN (90 kg N ha -1 ) + 25 % N (30 kg N ha -1 ) through vermicompost / FYM to curtail 25 % chemical load.

Table 1 .
Growth parameters as influenced by nitrogen management practices through different sources in wheat Treatment

Table 2 .
Yield attributes as influenced by nitrogen management practices through different sources in wheat

Table 3 .
Yield and economics as influenced by nitrogen management practices through different sources in wheat Selling Price of wheat : Grain : Rs. 15 kg -1 ; Straw : Rs. 1.50 kg-1