MSc

Cabbage is an important cool season annual vegetable crop belonging
to the family Brassicaceae. In Kerala, its cultivation was earlier restricted to the hill
tracts but with the introduction of tropical varieties and hybrids by the Kerala
Agricultural University, cultivation of the crop has spread to the plains also. The
heavy manurial and irrigation requirements of the crop create conducive conditions
for germination and growth of weeds, which reduce cabbage yield by 45-80 per cent.
Manual weeding is an effective method of weed control in cabbage, but due to the
time, labour and cost factors involved, it is not very acceptable.
The present experiment entitled “Weed management in cabbage (Brassica
oleracea var. capitata L.)” was conducted at Centre for Hi-tech Horticulture and
Precision Farming, Vellanikkara during November 2017 to March 2018 using the
variety NS 183. The objective of the study was to evolve a weed management
package for cabbage suited to the plains of Kerala. The treatments comprised of
application of two pre emergence herbicides (oxyfluorfen 0.2 kg/ha and
pendimethalin 1.5 kg/ha) both followed by a hand weeding at 30 DAP, high density
planting (0.6m x 0.3m) plus one hand weeding at 25 DAP, two mulching treatments
(coconut fronds and silver-black polythene), stale seed bed technique plus one hand
weeding at 30 DAP, hand weeding (25 and 50 DAP) and an unweeded control.
Broad leaf weeds were predominant (79%) in the field and the important
among them were Trianthema portulacastrum, Oldenlandia sp., Cleome viscosa and
Cleome burmanii.Polythene mulching of the field resulted in 100 per cent weed
control efficiency. Weed dry matter production and N, P and K removal by weeds
were higher in unweeded control, and dry matter production increased from 25DAP
to 50DAP. Pre emergence application of pendimethalin at 1.5 kg/ha was more
effective than oxyfluorfen at 0.2 kg/ha application (8% more effective at 25 DAP).
Stale seed bed technique recorded a weed control efficiency of 97.83 per cent
at 50 DAP and in high density planting weed control efficiency increased from 12.49
per cent at 25 DAP to 93 per cent at 50 DAP. Coconut frond mulching could not
control weeds effectively and weed control efficiency reduced from 55.52 per cent at
25 DAP to 48.96 per cent at 50 DAP.
Plant growth parameters were influenced by the different weed management
practices. Polythene mulched plots recorded the highest plant height and spread and
the lowest duration to 50 per cent head formation and maturity. The highest gross
(1987.27g) and net (858.47g) head weights were recorded in polythene mulched
plots, which was statistically superior to all other treatments. It was followed by
pendimethalin treatment with a net head weight of 523.40g. Highest yield of
16.83t/ha was obtained from polythene mulched plots, followed by pendimethalin
applied plots (10.26t/ha). Unweeded control recorded the lowest cabbage yield and
values for yield attributes.
Unweeded control recorded lower content of all the major nutrients (available
N, P and K) in soil. Nutrient contents were highest in plots with minimum weed
infestation. The population of soil microflora (bacteria, fungi and actinomycetes)
increased after experiment as compared to pre experimental period, indicating no
negative influence of herbicides on soil microbes.
Polythene mulching, even with higher cost of cultivation, resulted in the
highest net return and B:C ratio (2.17). Second highest B:C ratio was obtained with
pendimethalin treatment (1.63). Coconut frond mulching cannot be recommended as
a weed control measure as it was found ineffective in suppressing weed growth.
Polythene mulch was found to be the best method of weed control in cabbage.