Performance of canola oilseed rape (Brassica napus L.) in response to nitrogen application
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was carried out to assess the performance of canola oilseed rape (Brassica napus L.) in response to nitrogen application. Increased N-level increased days to first flower, flower initiation and completion of flowering however narrow spacing delayed flower initiation. Hyola PAC 401 took 52.7 days for flowers to initiate which was earlier than other two cultivars. Flowering period was comparable in GSC-7 and Hyola PAC 401 at narrow spacing. N levels and spacing affected siliqua duration in the three canola cultivars being comparable in GSC-7 and PGSH-52. Reproductive phase and days to maturity did not vary much with N levels. Reproductive phase was of 77 days in Hyola PAC 401 while maturity was one day earlier as compared to GSC-7 and PGSH-52. Physiological traits were maximum at flowering stage. LAI, PAR interception and extinction coefficient enhanced by 9.6%, 2.3% and 14.4% respectively with N125 however, at wider spacing a decline by 15.7%, 0.8% and 9.1 % respectively was observed. SPAD values increased with increase in N125 and 45 cm spacing. Chlorophyll a, chlorophyll b, total chlorophyll and carotenoids improved with N125 whereas chl a/chl b declined at all three stages of crop growth. Total chlorophyll increased by 12.8% and carotenoids by 5.0% with N125 whereas the respective increase was 9.3% and 3.4% with wider spacing. At flowering stage dry matter partitioning indicated higher accumulation into shoot (sink) followed by leaves (source) and least in root at wider spacing. N content enhanced by 31.7% in leaves with N125. N assimilating enzymes were maximum at flowering stage and increased with N level enhanced their activities. NR activity improved by 11.5%, NiR by 24.2%, GS by 12.2% and GOGAT by 35.2% over N100 at flowering stage. Increase in N level enhanced total soluble, reducing and non reducing sugars. Growth parameters, yield attributes, biological yield, seed yield and assimilate partitioning improved with N125. However the later were maximum at narrow spacing. Glucosinolate content was < 30 µmoles/g in three genotypes at two nitrogen levels and two spacings. Oil content decreased whereas protein content increased with N125. Seed yield enhanced only by 1.7% in PGSH-52 as compared to GSC-7 with recommended nitrogen and spacing, however with N125 increase was only 2% over Hyola PAC 401.
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