Nitrogen scheduling for canola oilseed rape (Brassica napus) sown on varied dates
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
A field study was conducted during rabi 2016-17 at the Punjab Agricultural University,
Ludhiana (30o54‟N, 75o48‟E) to investigate the influence of sowing time, dose and time of application
of nitrogen (N) on growth, productivity, nitrogen uptake and quality of oilseed rape (Brassica napus
L.). The experiment was laid out in split plot design in three replications with three sowing dates (15
October, 30 October and 15 November) in the main plots, whereas the sub plots comprised seven
treatments of dose and time of application of N viz; application of 100 and 125 kg/ha of N in two equal
splits at sowing and at initiation of stem elongation, 100 kg/ha of N in two splits as 25 kg at sowing and
75 kg at stem elongation, 100 kg/ha of N in three splits as 50+25+25, 25+50+25, 34+33+33 and 125
kg/ha of N in three splits as 50+50+25 at sowing, initiation of stem elongation and initiation of
flowering, respectively. Canola oilseed rape variety GSC 7 was sown at spacing of 45 cm x 10-12 cm.
Soil of the experimental field was loamy sand Ustochrept, neutral in pH, low in organic carbon and
available nitrogen and rich in available phosphorus and medium in available potassium. With delay in
each sowing from 15 October to 30 October to 15 November, the number of days required for
emergence, flowering and physiological maturity significantly increased. However delay in sowing
significantly reduced the plant height, dry matter accumulation (DMA) and PAR interception at
different growth stages, number of secondary branches per plant, seeds per siliqua and 1000 seed
weight, N content except in stem at 80 DAS and uptake by different plant parts at different growth
stages and in seed and stover at maturity. Crop sown on 15 October produced 4.1%, 27.3%, 2.9% and
10.8% higher seed, stover, oil and seed protein yield, respectively than 30 October sown crop which in
turn, out yielded 15 November sown crop by 36.1%, 36.4%, 41.2% and 40.9% for seed, stover, oil and
seed protein yields, respectively. Sowing dates had inconspicuous effect on different fatty acids of oil.
Higher dose of N (125 kg/ha) in general resulted in better growth, improvement in yield attributes,
yields (seed, stover, oil and protein) and N uptake than 100 kg/ha. However response of time of
application of N was variable. Application of N in two equal splits at sowing and initiation of stem
elongation resulted in more plant height, DMA, SPAD value at different growth stages than its
application in three splits. The highest seed yield (2681 kg/ha) and oil yield (1056 kg/ha) produced by
15 October sown crop with application of 125 kg/ha of N in three splits as 50 kg at sowing + 50 kg at
initiation of stem elongation + 25 kg at initiation of flowering was at par with the crop sown on 15
October with the application of 100 and 125 kg/ha of N in two equal splits and that sown on 30
October with application of 125 kg/ha of N in three splits but significantly higher than all other
treatments. The effect of dose and time of application of N on fatty acid composition of oil was not
significant.
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