physicochemical

Research Note
J.Res. ANGRAU 39(1&2)60-63, 2011
INTEGRATED APPROACH FOR WEED CONTROL IN RABI GROUNDNUT
(Arachis Hypogeae L)
S. SRINIVASA RAO, M. MADHAVI and C. RAGHAVA REDDY
Departmant of Agronomy, College of Agriculture,
Acharya N G Ranga Agricultural University,Rajendranagar – 500030
Groundnut (Arachis hypogaea L.) is an
important oil seed crop of Andhra Pradesh, which
has low productivity and high cost of production.
Area, production and productivity of groundnut during
rabi in India were 6.41 Mha, 9.18 MT, and 1432 kg
ha -1 during 2008, In AndraPradesh, the area,
production, and productivity of groundnut were 2.64
Mha, 5.07 MT and 1921 kg ha -1 respectively
(Department of Agriculture, AP, 2008-2009). Weed
infestation is considered as one of the major factors
in rabi groundnut production. Weed interference
resulted in yield losses ranging between 74 and 92
percent (Agostinho et al., 2006). Critical period of
crop weed competition for groundnut crop was
reported to be upto 45 DAS and weed free
environment during this period registered higher pod
yield (Rao, 2000). Usually, in groundnut, weeds are
controlled by physical methods and these cannot be
used at all times and all stages of crop growth.
Further, the labour availability for weeding is scarce
and expensive. Use of pre and post emergence
herbicides is the best alternative for weed control at
critical periods. Combination of physical and chemical
methods by use of post emergence herbicides like
Imazethapyr or Quizalofop-p-ethyl (Bhatt et al., 2008)
were suggested for controlling weeds effectively at
later stages of crop growth and maintenance of weed
free environment at critical stage of crop growth
(Sailaja et al., 2002). Therefore field experiment was
initiated to find out an effective and economical
integrated weed management practice in rabi
groundnut.
Field experiment was conducted at College
Farm, Rajendranagar of Acharya N.G. Ranga
Agricultural University. The soil was sandy loam
(Available N, P and K 252.9, 28.6 and 223 kg ha -1
respectively) with slightly alkaline reaction. The
experiment was laid out in randomized block design
with 12 treatments replicated thrice. The N, P 2
O 5
and
K 2
O @ 30, 40 and 50 kg ha -1 were applied as basal
through urea, single superphosphate and muriate of
potash respectively. The groundnut cv. K 134
(Vemana) was sown at a spacing of 22.5 cm X 10
cm on 16 th November 2008. Pre emergence herbicide
pendimethalin was applied on second day after sowing
and post emergence herbicides were applied at 20
DAS. Weed flora of the experimental field consisted
of grasses, sedges and broadleaved weeds.
Among the weed control treatments,
significantly lesser number of weeds were recorded
at harvest in treatments of handweeding twice (T 2
),
Quizalofop-p-ethyl fb handweeding at 40 DAS (T 12
),
pendimethalin fb handweeding at 40 DAS (T 10
),
intercultivation with star weeder fb handweeding at
40 DAS (T 4
) and imazethapyr fb handweeding at 40
DAS (T 11
) (54 m -2 , 55 m -2 , 59 m -2 , 60 m -2 , 62 m -2
respectively). Pendimethalin fb imazethapyr (T 8
)
recorded higher weed density of 145 m -2 (Table 1).
Unweeded check recorded highest total weed density
(T 1
) (353 m -2 ). Lower weed drymatter was obtained
under T 2
, T 4
, T 10
, T 11
, T 12
and T 8
treatments (33, 35,
36, 38, 40 and 51 g m -2 respectively) and weed control
efficiency (WCE) also exhibited the same trend
(85.5%, 84.1%, 83.2%, 83.2%, 81.3% and 76.1%).
The weed index was very low under treatments T 4
,
T 8
, T 10
and T 11
due to application of pre-emergence
herbicide which might have reduced the broad leaved
weeds and certain grasses at early stage of crop
growth (20 DAS). At 40 DAS, effective control of
grasses, sedges and broad leaved weeds was noticed
with hand weeding, intercultural operations and post
emergence application of herbicides. Imazethapyr
acts by inhibiting the enzyme (AHAS) activity and
causes the disruption of protein synthesis and other
subsequent bio-chemical reactions, which in turn
inhibits the plant growth. These findings are in
agreement with the results of Sasikala et al. (2002),
Chandrika, (2004). Highest pod and haulm yields were
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