Growth pattern and yield of canola oilseed rape (Brassica napus L) as influenced by direct seeding and transplanting on different dates and irrigation

Abstract

During the Rabi 2022-23 season, a field experiment took place at the Punjab Agricultural University, Ludhiana with the
objective to investigate the impact of different dates of sowing and transplanting, as well as irrigation scheduling, on the
growth and productivity of canola quality oilseed rape (Brassica napus L.) in sandy loam soil. Study comprised six
combinations of three dates (10 October, 30 October and 20 November) and two methods of crop establishment (direct
sowing and transplanting) as main plot and four irrigation schedules based on IW:CPE 0.8, IW:CPE 1.0, IW:CPE 1.2
and on crop growth stages as sub plot treatments. Treatments laid out in split plot design were replicated thrice. For
transplanting, 30 days old seedlings were used. Irrigation based on crop growth stages was applied at 30 days after
sowing, flowering and siliquae formation stages. Canola quality oilseed rape variety GSC 7 was sown/transplanted at
spacing of 45 cm × 10-12 cm. Delay in sowing delayed the emergence. With delay in each sowing/transplanting from 10
October to 20 November, crop required significantly more number of days for initiation of flowering but less number of
days for completion of flowering and physiological maturity. Delay in sowing/transplanting caused significant reduction
in plant height, dry matter and PAR (photosynthetically active radiation) interception and number of primary branches
plant-1. Crop sown/transplanted on 10 October produced 16.8% higher seed yield than 30 October sown/transplanted
crop (2719 kg ha-1) which in turn significantly out yielded 20 November sown/transplanted crop by 60.0%. Transplanted
crop took significantly less number of days for initiation and completion of flowering and physiological maturity than
direct sown crop. Transplanted crop also attained significantly more plant height, accumulated significantly more dry
matter and intercepted more PAR and produced 12.2% higher seed yield (2631 kg ha-1) as compared to direct sown crop.
Application of irrigations at IW:CPE 1.2 resulted in significantly higher plant height (except at maturity), DMA and
PAR interception than other irrigation schedules. Irrigation application at IW:CPE 1.2 resulted in significantly higher
seed yield (2559 kg ha-1) as compared to the IW:CPE 0.8 (2402 kg ha-1). The seed yield and harvest index of the crop that
was transplanted on 30 October was comparable to the crop that was directly sown on 10 October. However, the crop that
was transplanted on 30 October and 20 November had a significantly higher seed yield compared to its direct sowing.