Effect of seed priming , nitrogen levels and moisture regimes on yield and yield components of wheat

The experiment was layout at the Agronomy research farm, The University of Agriculture, Peshawar, Pakistan, in winter season 2015-16, to study the effect of moisture regimes, seed priming and nitrogen levels on yield and yield components of wheat. The experiment was consist of three factors i.e. moisture regimes (low, and high), seed priming (dry seed, water soaked seed and P-primed seed) and N levels (0, 60, and 120 kg ha). The results indicated that higher moisture regime gives higher number of spike m (332), and thousand grain weight (45g), while in case of N-levels more spike m (343), grains spike (49.20), thousand weight (46g), biological yield (10678 kg ha) and grain yield (4433 kg ha) ware recorded at 120 N kg ha. In case of priming P-primed seed gives higher spike m, grains spike (49.4), 1000 grains weight (45.4g), biological (9654 kg ha) and grain yield (4032 kg ha) followed by water soaked seeds.


Introduction
Wheat (Triticum aestivum L.) is the major crop among cereals in the world.It is the basic food of Pakistan and provides about 73 % calories and 12 % protein [1].Wheat is also used for livestock and poultry feed.In Pakistan wheat is cultivated both in irrigated and barani areas.The total area occupied by wheat during 2014-15 in Pakistan was 9046 thousand ha, which produced 25032.9thousand tones food grain, while in KP the total area occupied by wheat was 769.5 thousand ha, Average yield of wheat in Khyber Pakhtunkhwa (KP) is around 1550 kg ha-1, which is half of the national average [2].Punjab is the leading producer of wheat.In KP, more wheat is grown in barani (61%) than in irrigated area (39%).Besides grain, wheat straw (bhossa) is also used as roughage for livestock.Seed priming comprises the soaking of seed in water or any chemical or nutrient solution.Due to seed priming a rapid brick down of endosperm occur due to which seed germinate rapidly because priming accelerate the function of enzymes.Due to these processes the seed germinate earlier than dry seed [3].Priming has a deep effect on the quality and yield of wheat.To achieve high quality yield for it vigor and viability of seed is essential.Seed priming improve the vigor and uniformity of germination [4].Many methods have been used for the seed priming for the purpose to enhance its germination and seedling growth of many crops [5].For wheat seed priming water is also used as a good medium [6].Primed seed of wheat with P increase emergence m -2 , tiller m -2 , grains spike -1 , thousand grain weight and grain yield as compared to dry seed [7].Seed priming with P improves emergence and seedling growth with regard to untreated seed and showed that water and nutrient can also be used for the priming purpose to increase emergence and early seedling growth of maize In this experiment we determined the influence of treated seed on emergence, plant growth and yield wheat at two contrasting seedbed moisture condition and available nitrogen.

Materials and methods
The experiment was conducted at Agronomy research farm, The University of Agriculture Peshawar in winter 2015-2016, to study the response of seed priming, nitrogen and soil moisture regimes on yield components and overall wheat yield.The experiment consisted of three factors i.e. moisture regimes (Low and High), seed priming (dry seed, water soaked, seed primed with 0.2% P solution) and nitrogen levels (0, 60, 120 kg ha -1 ).Two separate experiments were conducted in RCBD, one under high moisture seedbed condition and other under low moisture seedbed condition.Date of sowing was 25 th November 2015.Treatment combination of seed priming and N levels were kept in both experiments with three replications.Low moisture plots were irrigated two weeks before sowing while high moisture plots were irrigated a week before sowing.Both low and high moisture plots were not irrigated till 40 th day after sowing.Soil moisture of both low and high moisture regimes were 23 and 30 %, respectively at the time of sowing of the crop.Wheat variety Siran-2010 was cultivated at the rate of 120 kg ha -1 in a subplot size of 4.8 m by 3 m having 16 rows 3 meter long and row to row distance was 30 cm.Nitrogen was applied in three split levels, one third each at sowing, tillering and boot stages.Seed priming was consisted of dry seed, water soaked seed and seed primed in 0.2% P solution.KH2PO4 was used as source of P. For primed seeds, 180 g of seed plot -1 was put in polyethylene bags having pores and then were treated with water for 12 hours in either distilled water or in a 0.2% aqueous solution of P. After priming, bags were removed, drained and then surface dried in shade for around half an hour to facilitate clump-free sowing.Phosphorous at the rate of 90 kg ha -1 was applied at sowing time.Sources of phosphorous and N were SSP and urea, respectively.All the standard agronomic practices were uniformly adopted for the experiment.Data ware recorded on the following parameters Early plant growth (Fresh shoot weight) For recording data on early plant growth, randomly selected five tillers in each plot were cut at the base and data on fresh shoot weight, plant height and number of leaves at 14, 21, 28, 35, 42 and 49 days after sowing were recorded.Spike m -2 Data on spikes m -2 was determined by counting the spikes in three randomly rows of one meter length and then converted into spikes m -2 .Grains spike -1 Grains from five randomly selected spikes were obtained by hand threshing and were counted and converted into average number of grains spike -1 .Thousand grain weight (g) Thousand grains were counted that were randomly picked from each sub plot and weighed with a digital balance.Biological yield (kg ha -1 ) Four central rows were harvested in each subplot and sun dried and bundles were weighed and its biological yield was converted into kg ha -1 .Grain yield (kg ha -1 ) Small wheat thresher was used for threshing the biological yield taken from four central rows in each sub plot.After threshing the grains were weighed by balance and from it yield kg ha -1 was calculated.

Harvest index (%)
Harvest index was calculated as the ratio of grain yield to the total biological yield.

Statistical analysis
Data were statistically analyzed using the procedure suitable for RCBD design with significant F-value.The least significant difference (LSD) test was applied for the comparison of treatments means at 5% level of probability steel et al. [15].

Results and discussion
Fresh shoot weight Data pertaining fresh shoot weight of wheat are given in Table 1.Analysis of the data showed that the effects of moisture, N levels and seed priming were not significant, while fresh shoot weight significantly varied during different weeks (W).Similarly, all interactions were found non-significant.
Fresh shoot weight significantly increased with time interval.It increased from 0.03 g to 0.06g (88 %) during first week.During second week, it increased 58 % from 0.06g to 0.10 g.In week third, it increased from 0.10g to 0.12 g (16 %).It increased from 0.12 g to 0.20g (63 %) during week four.Similarly, in week five, it increased from 0.20g to 0.28g ( 39

Spike m -2
Data regarding spike m -2 of wheat are given in Table 1.Analysis of the data showed that the effects of moisture, nitrogen and seed priming were significant while all the interactions were not significant.Maximum spike m -2 was recorded for high moisture plots (332) as compared to low moisture plots (294).Nitrogen level increased number of spike m -2 .Higher number of spike m -2 were recorded for 120 kg N ha -1 (343) followed by 60 (306) and 0 kg ha -1 (289).
Higher number of spikes were recorded for P primed seed (337) followed by water soaked seed (309) and dry seed (293).

Results are supported by Brahma et al. [19]
who recorded maximum number of spikes m -2 in frequently irrigated treatments.Similarly, Akhtar [20] found that spikes m -2 significantly increased by increasing levels of N Harris et al.
[21] argued that increase in spikes m -2 due to priming might be due to improved emergence and better seedling growth.

Grains spike -1
Data regarding grains spike -1 of wheat are given in Table 1.Analysis of the data revealed that moisture effect on grain spike -1 was not significant while the effects of nitrogen levels and seed priming were significant.All the interactions were found non-significant.Higher grains spike -1 was recorded for 120 kg N ha -1 (49.2) and 60 kg N ha -1 (48.7) as compared to 0 kg N ha -1 (45.8).Seed priming improved grains spike - 1 .Higher grains spike -1 were recorded for P priming treatment (49.  1.Data analysis showed that moisture, nitrogen and seed priming positively affected thousand grain weight of wheat.Similarly, all the interactions were not significant.High moisture plots resulted in higher thousand grain weight (45g) as compared to low moisture plots (43g).Thousands grain weight increased with higher level of N. Higher thousand grain weight was obtained at 120 kg N ha -1 (46 g) followed by N level of 60 (44 g).While lower thousand grain weight was recorded for 0 kg N ha -1 (42 g).Seed priming improved thousand grain weight.Higher thousand grain weight was recorded for P primed and water soaked seed (45.48 and 43.29 g, respectively).Lower thousand grain weight was recorded for dry seed (42.7 g).These results are supported by the findings of Jamal [26] who stated that plots received four irrigations gave maximum grain weight and the lowest grain yield by two irrigations.Similar views by Zubair et al.
[27] who reported that higher levels of nitrogen increased vegetative growth and more photosynthesis occurred and more photosyntheate were transferred to sink which enhanced grain weight.Likewise, Basra et al.
[28] concluded higher grain weight and biomass for primed seeds.Biological yield (kg ha -1 ) Data pertaining biological yield are shown in Table 2. Data analysis revealed that nitrogen levels and seed priming significantly affected biological yield of wheat.The effect of moisture was not positive.Similarly, all the interactions were not positive.Biological yield increased with increasing level of N. Higher biological yield was obtained at 120 kg N ha -1 (10678 kg ha -1 ) followed by N level of 60 kg N ha -1 (9515 kg ha -1 ).Lesser biological yield (7763 kg ha -1 ) was obtained at 0 kg N ha -1 .Seed priming improved biological yield.Higher biological yield of 9654 kg ha -1 and 9413 kg ha -1 was recorded for P primed seed and water soaked respectively, while dry seed resulted in lower biological yield (8889 kg ha -1 ).Grain yield (kg ha -1 ) Grain yield data of wheat are given in Table 2. Data analysis revealed that nitrogen levels and seed priming positively influenced wheat grain yield.Moisture and interaction effect was non-significant.With the increase in level of N yield of grains also increased.Maximum grain yield was obtained at 120 kg N ha -1 (4433 kg ha -1 ) followed by N level of 60 kg N ha -1 (4011 kg ha -1 ).Minimum grain yield (3160 kg ha -1 ) was obtained at 0 kg ha -1 .Seed priming improved grain yield.Maximum grain yield of 4032 and 3882 kg ha -1 were recorded for P primed and water soaked seed, respectively.Lower grain yield was recorded for dry seed (3691 kg ha -1 ).

Harvest index (%)
Data pertaining to harvest index of wheat are given in Table 2. Obtained data showed that the effects of moisture, nitrogen levels and seed priming were not significant.Similarly, all the interactions were also not significant.Though the effect of moisture was not significant but more harvest index (41.7%)was recorded for high moisture plots compared to low moisture plots (41.3%).Higher harvest index was recorded for 60 kg N ha -1 (42.2%) followed by 120 (41.5%) and 0 kg N ha -1 (40.8%).Higher harvest index was obtained for P primed seed (41.7%) followed by dry seed (41.6%) and water soaked seed (41.1%).Results are also in disagreement with Akhtar [20] who stated that harvest index was significantly affected by nitrogen levels.Likewise, Shatab and khan [34] also reported that harvest index increased with P priming.

Conclusion
High moisture (seedbed) resulted in higher yield and yield components as compared to low moisture seedbed.N at the rate of 120 kg N ha -1 produced higher yield and yield components as compared to other levels.

Table 2 . Biological yield (kg ha -1 ), grain yield and harvest index (%) of wheat as influenced by moisture, N levels and seed priming Moisture Biological yield (kg ha -1 ) Grain yield (kg ha -1 ) Harvest index %
Results are not similar with Pandey et al. [22] who found linear response between number of irrigations and grain yield.Similar views by Marino et al. [30] who determined that N application increased biomass and grain yield of the crop.Ghosh et al. [31] determined higher grain yield for primed seed as compared to dry seed.Water is also used as a medium for seed priming due to which yield increases.(Harris et al.