STUDIES ON DEFOLIANTS IN HIGH DENSITY PLANTING COTTON-GREENGRAM SEQUENCE
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Date
2021-12-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Acharya N.G. Ranga Agricultural University, Guntur
Abstract
A field experiment entitled “Studies on defoliants in high density
planting cotton- greengram sequence” was conducted during 2018-19 and
2019-20 on clay soils at Agricultural College Farm, Bapatla. The experiment
was conducted in split-plot design with nine treatments and replicated four times
using Suraj variety cotton. The main plots were defoliants D1- Dropp Ultra @
250 ml ha-1
, D2- Mepiquat chloride @ 100 ml ha
-1 and D3-Etherel @ 3000 ppm,
the sub plots were times of application viz., 80 % Boll Opening (T1), Node
Above Cracked Boll (NACB-T2) and Node Above White Flower (NAWF-T3).
During the two years of study and in pooled data, defoliants, times of
application and their interaction did not alter the plant height and drymatter
accumulation significantly from 30 DAS to 120 DAS. At 21 days after defoliants
spray, reduction in plant height was observed at all the three different times of
application. Mepiquat chloride @ 100 ml ha-1
recorded maximum drymatter at
harvest which was on par with Etherel @ 3000 ppm and at 80% Boll Opening
recorded highest drymatter, which was found on par with NACB in 2018. In
pooled data, interaction of Mepiquat chloride applied at 80 % Boll Opening
(D2T1) recorded highest drymatter accumulation.
In two years of experimentation and in pooled data, at 21 days after
defoliant spray, significantly highest percent defoliation was noticed with Dropp
Ultra @ 250 ml ha-1
and 80 % Boll Opening, which was on par with Node
Above Cracked Boll. Sympodial branches and total number of bolls plant-1
were
not significantly influenced by defoliants and time of application and their
interaction. Lowest number of unopened bolls plant-1 and highest boll opening
percentage were recorded with Dropp Ultra @ 250 ml ha-1
and 80% Boll
Opening. Number of picked bolls plant-1 were more with application of Dropp
Ultra @ 250 ml ha-1 which was on par with Etherel during first year, and 80 %
Boll Opening which was found on par with NACB during second year. The
xv
interaction between Dropp Ultra applied at 80 % Boll Opening recorded
maximum number of picked bolls plant-1
and highest boll opening percentage.
Highest boll weight was recorded at 80 % Boll Opening, which was found on a
par with Node Above Cracked Boll. Test weight, lint index, ginning percentage
and quality parameters were not significantly influenced by either defoliants, or
time of application and their interaction during both the years and in pooled data.
Highest seed cotton yield was obtained with application of Dropp Ultra
@ 250 ml ha-1
, which was found on par with Etherel @ 3000 ppm and 80% Boll
Opening during first year of study and in pooled data. In 2019, Dropp Ultra and
80 % Boll Opening recorded highest seed cotton yield. Maximum stalk yield
was recorded with Mepiquat chloride and 80 % Boll Opening which was found
on par with Node Above Cracked Boll. Highest harvest index was found with
Dropp Ultra and it was found on par with Etherel. Application of defoliants at
three times of application had reduced the crop duration during both the years.
Degree days were in the range of 260-315 °C days which hastened the
defoliation process during both the years.
Plant height and drymatter accumulation at harvest of greengram grown
after cotton as sequence crop was not influenced by defoliants applied in
previous crop during both the years and in pooled data. Greengram sown in
Node Above Cracked Boll plots recorded highest drymatter accumulation and
was found to be on par with early sown plots. The highest greengram seed yield
was recorded under Dropp Ultra which was on par with Etherel. In pooled data,
D1 was significantly superior over other treatments. Greengram sown in Node
Above Cracked Boll plots recorded highest seed yield and was on a par with
Node Above White Flower treatment during both the years and in pooled
data.The highest haulm yield was recorded when greengram was sown in Dropp
Ultra @ 250 ml ha-1
and Node Above Cracked Boll applied plots which was on
par with T3 (Node Above White Flower). Interaction between these two factors
was found to be non-significant. After harvest of both the crops, Dropp Ultra
received plots recorded highest soil nitrogen and were on par with Etherel in
pooled data and soil phosphorus was maximum in Dropp Ultra received plots.
During both the years and in pooled data, total cotton equivalent yield
was highest with Dropp Ultra @ 250 ml ha-1
(D1) which was on par with Etherel
@ 3000 ppm (D3) in 2018 and in pooled data. 80 % Boll Opening recorded
maximum total cotton equivalent yield, which was on par with Node Above
Cracked Boll. Land Use Efficiency and Production Use Efficiency in terms of
yield and returns were highest in late sown (80 % boll opening) plots. The
highest net returns and returns per rupee investment were noticed with
application of defoliant Dropp Ultra @ 250 ml ha-1
(D1) and at 80% Boll
Opening.
From the two years trial conducted it can be inferred that Dropp Ultra and
Etherel can be used in cotton as defoliants at 80 % Boll Opening and greengram
can be grown in sequence in Krishna agro-climatic zone of Andhra Pradesh.
Description
STUDIES ON DEFOLIANTS IN
HIGH DENSITY PLANTING
COTTON-GREENGRAM SEQUENCE