Research Article
Frequency of Various N Levels, Lodging and Seed Quality in Wheat
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Sherin Khan
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Jehan Bakht
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Wajid Ali Shah
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Wheat consumption in Pakistan is going to increase significantly in the next decade and estimated demand in year 2010 is approximately 26.4 million tons. The additional requirement will have to be met by increasing substantially the yield ha-1 for which there is an ample scope. The required future target can be achieved either by increasing area under cultivation or maximizing unit-1 area. The scope for greater hectarage is limited due to competition with other crops e.g., oil seeds, pulses, sugar and fodder crops. Therefore, major emphasis to be laid on increase hectare-1 yield, which can only be achieved when an appropriate production technology is adopted, including use of high yielding varieties, proper level of fertilizer and its time and method of application, weed control etc. Among the several factors responsible for low yield balanced fertilizer and its application time are important limited factors, for obtaining high yield. In order to get better yield, the wheat crop must be planted in rows with proper spacing and application of well-calculated amount of fertilizer.
Piech and Stankowski (1988) reported that the yield increase with higher N rates is mainly due to increase in number of grains spike-1. Increasing levels of irrigations and N acted synergistically in increasing grain yields, N uptake and utilization of fertilizer N. Sud and Arora (1990) concluded that increasing N rate increased number of tillers plants-1 and ears number m-2 but number of grains ear-1 and 1000 grain weight were not changed. Late sowing and higher N rates reduced 1000 grain weight, high N rates increased lodging and diseases incidence but also increased protein yield, grain protein and dry gluten content (Mazurek and Kus, 1991).
Keeping in view the importance of N in plant growth and development, the study was carried out to determine the various nitrogen levels and their frequency of application on lodging and seed quality in wheat.
Field experiment to study the frequency of various N levels, lodging and seed quality in wheat was conducted at Malakandhar Research farms of NWFP Agricultural University, Peshawar, during 1999-2000. The land was thoroughly prepared as required for wheat sowing. The experiment was laid out in Randomized Complete Block Design (RCB) with split plot arrangement using frequencies in subplot and fertilizers in main plots. Variety Tatara 96 was sown at the rate of 100 kgha-1. The following factors and their levels were studied in the experiment.
Nitrogen levels:
Application frequencies:
F1 | = | All fertilizer at seeding time. |
F2 | = | All fertilizer at second irrigation (50 days after seeding). |
F3 | = | 50 % at seeding time, 50 % at second irrigation (50 days after seeding). |
F4 | = | 33.3 % at seeding time, 33.3 5 at second irrigation (50 days after seeding), 33.3 % at boot stage. |
F5 | = | 25 % at seeding time, 25 % at second irrigation (50 days after seeding), 25 % at boot stage, 25 % after anthesis. |
Data were recorded on the Number of productive tillers m-2, number of spikelets spike-1, grains spike-1, grain yield (kg ha-1), biological yield (kg ha-1), harvest index, germination test (%) of fresh seed, gain size (by weight in gram) and vigor test.
Number of productive tillers m-2 were recorded by counting the number of tillers in one meter length area of the three central rows in each subplot and their mean was then calculated. Number of spikelets spike-1 was recorded by counting the number of spliklets of 10 labeled spikes in each treatment. For calculating number of grains spike-1, five spikes treatment 1 were randomly selected in each sub plot and then their grains were counted and divided by 5 to get the average grains spike-1. Grain yield, biological yield and harvest index in each subplot was determined and then converted into kg ha-1.
The data collected during the experiment was analyzed according to RCB design and upon obtaining significant differences Least Significant Differences (LSD) test was applied (Steel and Torrie, 1980).
Results and Discussion
Levels of nitrogen and application frequencies had a significant (P≤ 0.05) effect on productive tillers m-2, while nitrogen levels x application frequencies (NxF) interaction had a non-significant effect (Table 1). Mean values for nitrogen levels showed that productive tillers m-2 increased with each increment of nitrogen levels upto 170 kg ha-1, which produced 314.45 tillers m-2, and statistically at par with 200 kg N ha-1. While plots fertilized with 140 and 110 kg N ha-1 produced minimum tillers m-2. These results are also confirmed by Ayoub et al. (1994), who reported that tillers m-2 increased with increasing N rate. In case of application frequencies, maximum of 339.19 tillers m-2 were produced by plots applied with nitrogen in 2 split doses (50 % at seeding time and 50 % at second irrigation), while minimum of 290.63 tillers m-2 were recorded in plots applied with nitrogen all at seeding time. Bhatti (1983) and Rehman et al. (1993) reported that split application of fertilizer N has been found effective in crop yields with increasing tillers m-2 compared with the full application of N fertilizer at sowing time.
Analysis of the data (Table 2) showed that nitrogen levels and application frequencies had a significant (P≤ 0.05) affected by number of spikelets spike-1. Mean value for nitrogen levels indicated that number of spikelets spike-1 was higher (20.52) in plots received 170 kg N ha-1. While minimum number of spikelets spike-1 were recorded in those plots, which received 110 kg N ha-1. Spikes taken from plots fertilized with nitrogen in 2 split doses produced significantly higher number of spikelets spike-1 while nitrogen applied in full doses at seeding time recorded minimum spikelets. Similar results were also reported by Piech and Stankowski (1988).
Various nitrogen levels and their application frequencies had a significant (P ≤ 0.05) effect on grains spike-1 while NxF interaction had a non significant effect (Table 3). Mean values for nitrogen levels revealed that application of 170 kg N ha-1 produced higher 62.65 grains spike-1 as compared with plots treated with 110 kg N ha-1, which gave lesser number of 56.60 grains spike-1. Mean values for application frequencies showed that N application in 2 doses gave maximum number of 63.06 grains spike-1. The lowest number of 56.60 grains spike-1 was obtained from first frequency i.e. (all fertilizer at seeding time). These results agree with the findings of Ratthi and Ramsingh (1973), who reported that the application of nitrogen increased grains spike-1. Grain yield is one of the most important parameters and the ultimate output of any cereal crop.
Analysis of the data (Table 4) indicated that various nitrogen levels and their application frequencies had a significant (P ≤ 0.05) effect on grain yield, while the effect of interaction between various nitrogen levels and their application frequencies was non significant. Maximum grain yield of 4644.00 kg ha-1 was obtained from plots fertilized at 170 kg N ha-1, while minimum of 3740.00 kg ha-1 grain yield was produced in plots treated with 110 kg N ha-1. Similar results were also reported by Nass et al. (1990) and Ayoub et al. (1994), who found that the grain yield increased with increasing nitrogen application. In case of application frequencies, maximum grain yield of 4762.50 kg ha-1 was obtained from those plots which received nitrogen in 2 split doses (i.e., 50 % at seeding, and 50 % at second irrigation) while minimum grain yield of 3937.50 kg ha-1 was produced by plots applied with nitrogen in full at seeding time. These results agree with those reported by Shah (1997), who concluded that split application of N fertilizer has been found effective in increasing crop yields compared with full application of N fertilizer at seeding time.
Analysis of the data (Table 5) indicated that various nitrogen levels and their application frequencies had a significant effect (P ≤ 0.05) on biological yield, while non significant response was observed due to interaction between nitrogen levels and their application frequencies. Highest biological yield of 17799.30 kg ha-1 was obtained from plots fertilized at the rate of 200 kg N ha-1, while the lowest biological yield of 15254.70 kg ha-1 was obtained from those plots, which were treated at the rate of 100 kg N ha-1.
Table 1: | Productive tillers m-2 as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=14.23 LSD Values at 5% for frequency of application=16.96 |
Table 2: | Spikelets spike-1 as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=0.1662 LSD Values at 5% for frequency of application=0.2905 |
Table 3: | Grains spike-1 as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=1.943 LSD Values at 5% for frequency of application=1.734 |
Table 4: | Grain yield (kg ha-1) as affected by varying nitrogen levels and their frequency of application in wheat |
Table 5: | Biological yield (kg ha-1) as affected by varying nitrogen levels and their frequency of application in wheat |
Table 6: | Harvest index (%)as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=1.392 LSD Values at 5% for frequency of application=1.823 |
Table 7: | Germination % age as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=1.264 LSD Values at 5% for frequency of application=1.190 |
Table 8: | Grain size (mg) as affected by varying nitrogen levels and their frequency of application in wheat |
Mean of the same category followed by different letters are significantly different from one another at 5% level of probability. LSD Values at 5% for nitrogen levels=11.46 LSD Values at 5% for frequency of application=5.601 |
Table 9: | Seed vigor (Seedlings dry weight, mg) as affected by varying nitrogen levels and their frequency of application in wheat |
Mean values for application frequencies revealed that all fertilizer at second irrigation (i.e., 50 days after seeding) gave higher biological yield of 17999.56 kg ha-1. The lowest biological yield of 15708.25 kg ha-1 was obtained from plots treated with N at 50% at seeding, 50% at second irrigation. Similar results were also reported by Graham et al. (1983), who revealed that grain yield and straw yield were increased with increase in nitrogen levels. Harvest index was significantly (P ≤ 0.05) different due to various nitrogen levels, their application frequencies whereas NxF (interaction) showed a non significant effect.
Plots treated with highest doses of N i.e., 170 kg ha-1 had high harvest index (28.13%), followed by nitrogen levels of 110 kg ha-1) with a harvest index value of 24.65% (Table 6). In case of application frequencies highest harvest index value of 30.37% was recorded in treatments applied with nitrogen in 2 split doses (i.e., 50 % at seeding and 50 % at second irrigation), while lowest harvest index (22.88 %) was recorded in treatments applied with full dose of N at 2nd irrigation. Percent germination was significantly (P ≤ 0.05) affected by N levels and application frequencies, whereas interaction was non significant. The data (Table 7) showed that highest germination (89.95 %) was observed in plots applied with nitrogen at the rate of 140 kg ha-1, whereas minimum germination (81.60 %) was recorded in plots applied with nitrogen at the rate of 200 kg ha-1. In case of application frequencies maximum germination percentage (87.75) was recorded for F3 i.e., (50 % at seeding and 50 % at second irrigation).
Data (Table 8) revealed that grain size was significantly (P ≤ 0.05) affected by nitrogen levels and application frequencies, while their interaction was non significant. Mean values for nitrogen levels indicated that maximum grade recovery of 244.30 kg ha-1 (which revealed 81.40% bigger and 18.60 % smaller seed size) was obtained from 140 kg N ha-1, while minimum of 215.30 kg ha-1 (which revealed 71.80% bigger and 28.20% smaller seed size) was recorded in plots received 200 kg N ha-1. In case of application frequencies maximum grade recovery of 236.80 kg ha-1 (which revealed 78.90 % bigger and 21.10 % smaller seed size) was recorded in those treatments applied with nitrogen in 2 split doses (i.e., 50% at seeding and 50% at second irrigation) while lowest seed grade recovery 222.70 kg ha-1 (which revealed 74.20 % bigger and 25.80% smaller seed size) was recorded in those treatments applied with nitrogen all at second irrigation. Statistical analysis of the data (Table 9) showed that nitrogen levels, their application frequencies and also NxF interaction did not significantly affect seed vigor.