Microclimate modification in gobhi sarson (Brassica napus L.) by debranching and defoliation under different dates of sowing
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Date
2014
Authors
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Publisher
Punjab Agricultural University, Ludhiana
Abstract
The experiment was conducted at the Research Farm, School of Climate Change and
Agricultural Meteorology, Punjab Agricultural University, Ludhiana to study “Microclimate
modification in gobhi sarson (Brassica napus L.) bydebranching and defoliation under different dates
of sowing” during rabi season of 2013-14. The experiment was laid out in split plot design with three
sowing dates (October 10, October 25 and November 10) and two varieties (GSC-6 and GSL-2) in
main plots; and debranching and defoliation treatments along with the control in sub plots with three
replications. The number of days taken for different phenological events of crop reduced with delay in
sowing from 10th October to 10th November which shortened the vegetative and reproductive phase.
The photosynthetically active radiation interception was higher in variety GSC-6 at pod formation and
pod filling stages while at flowering stage, it was higher in variety GSL-2. In defoliation and
debranching treatments PAR interception was increased by 4 to 7 per cent over control. The agrometeorological
indices viz. growing degree days (GDD), photo-thermal units (PTU), helio-thermal
units (HTU) were higher under 10th October sowing and decreased with each delay in sowing. The
relative humidity was low under debranching and defoliation treatments. There was a slight increase in
canopy temperature was also found under defoliation and debranching treatments over control. Crop
sown in October recorded higher number of primary branches per plant, number of secondary branches
per plant siliquae per plant, seeds per siliquae and test weight as compared to November sown crop.
Varieties showed non-significant differences in all the above parameters except test-weight. Defoliation
treatment recorded significantly higher number of secondary branches and siliquae per plant than
debranching and control, however, significantly higher number of seeds per siliqua and test weight was
recorded in debranching treatment over defoliation and control. Variety GSC-6 produced higher seed
yield than GSL-2, with significant decrease in 10th November sown crop as compared to October
sowing. Debranching produced significantly higher yield followed by defoliation and control in 10th
and 25th October sown crop. However, November sown crop resulted in significantly lower seed yield
in defoliation treatment, while debranching and control produced similar seed yield. The information
from this study will help in management of microclimate through canopy modification and agronomic
means, which could result in higher productivity of gobhi sarson. Moreover, the defoliation and
debranching of gobhi sarson provides the fodder yield in addition to seed yield, which may compensate
the labour cost involved in such practices.
Description
Keywords
Agricultural Meteorology, gobhi sarson, Agronomy, PAR, Brassica napus L.