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NITROGEN AND WEED MANAGEMENT FOR MAXIMIZING THE PRODUCTIVITY AND QUALITY OF AROMATIC RICE UNDER AEROBIC CULTURE IN SOUTHERN AGRO-CLIMATIC ZONE OF ANDHRA PRADESH

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Title NITROGEN AND WEED MANAGEMENT FOR MAXIMIZING THE PRODUCTIVITY AND QUALITY OF AROMATIC RICE UNDER AEROBIC CULTURE IN SOUTHERN AGRO-CLIMATIC ZONE OF ANDHRA PRADESH
 
Creator TIRUMALA REDDY, S
 
Contributor SRINIVASULU REDDY, D
 
Subject weeds, rice, control methods, nitrogen, grain, yields, developmental stages, crops, drying, land resources
 
Description Field experiments were carried out for two consecutive years of rabi,
2009, and 2010 on sandy clay loam soils of S.V. Agricultural College, Tirupati to
evaluate the nitrogen and weed management practices for maximizing the
productivity and quality of aromatic rice under aerobic culture in Southern Agroclimatic
Zone of Andhra Pradesh. The experiment was laid out in split plot
design, replicated thrice. The treatments consisted of four levels of nitrogen viz.,
100 kg ha-1 (N1), 120 kg ha-1(N2), 140 kg ha-1(N3) and 160 kg ha-1 (N4) as main
plots, seven weed management practices viz., Un-weeded check (W1), Pre
emergence (PE) application of pretilachlor @ 500 g a.i ha-1 (W2), PE of
oxadiargyl @ 75 g a.i ha-1 (W3), PE of pyrazosulfuron ethyl @ 20 g a.i ha-1(W4),
PE of pretilachlor @ 500 g a.i ha-1 followed by (fb) HW at 25 DAS (W5), PE of
oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS(W6) and PE of pyrazosulfuron ethyl
@ 20 g a.i ha-1 fb HW at 25 DAS(W7) as sub plots. The test variety of rice was
Sugandha samba (RNR 2465).
Growth parameters of aromatic rice increased with increasing nitrogen
levels and recorded the highest values with the application of 160 kg N ha-1,
which was comparable to 140 kg N ha-1,while at their lowest with 100 kg N ha-1.
xviii
Among weed management practices, pre emergence application of oxadiargyl @
75 g a.i ha-1 fb HW at 25 DAS, resulted in producing the highest growth
parameters, which was statistically on par with PE application of pyrazosulfuron
ethyl @ 20 g a.i ha-1 fb HW at 25 DAS, while the lowest was recorded with unweeded
check.
All the yield attributes viz., number of panicles m-2, panicle length, total
number of grains panicle-1, number of filled grains panicle-1 and thousand grain
weight recorded the highest values with the application of 140 kg N ha-1, and
further increase in nitrogen level 160 kg ha-1, yield attributes decreased slightly.
The lowest values of yield attributes observed with 100 kg N ha-1. Pre emergence
application of oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS was effective and it
was at par with pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at 25 DAS in
producing all the yield attributes. The lowest values of above parameters were
found with un-weeded check. With regard to spikelet sterility, the reverse trend
was recorded.
The highest grain yield and harvest index was realized with the application
of nitrogen 140 kg ha-1, where as the highest straw yield was produced with 160
kg N ha-1. The lowest values of all the above were noticed with 100 kg ha-1. The
highest grain and straw yields including harvest index were obtained with pre
emergence application of oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS, which
was comparable with PE application of pyrazosulfuron ethyl @ 20 g a.i ha-1 fb
HW at 25 DAS. All the above parameters were recorded at their lowest with unweeded
check.
Grain quality parameters viz., kernel length, breadth, amylose content of
grain was influenced only by nitrogen levels and recorded the highest values with
the application of 160 kg N ha-1, which was comparable to 140 kg N ha-1
, where
as milling percent and protein content of grain was significantly influenced by
both nitrogen and weed management practices and milling percent followed
exactly the similar trend of grain yield and the protein content of grain followed
the similar trend as that of straw yield. The head rice recovery, length : breadth
ratio and volume expansion of rice were not influenced either by nitrogen or
weed management practices during both the years of study.
At all the stages of observation, the highest nitrogen uptake by crop was
recorded with highest level of nitrogen 160 kg ha-1, where as phosphorus and
potassium uptake was recorded with 140 kg N ha-1 and these were in turn
comparable with each other. The highest nitrogen, phosphorus and potassium by
crop was recorded with PE application of oxadiargyl @ 75 g a.i ha-1 fb HW at 25
DAS, which was comparable with pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at
25 DAS, while the lowest were recorded with un-weeded check (W1).
Weed species belonging to eight taxonomic families were observed in the
experimental field, of which five species were grasses, three species were sedges
and twelve species were broad leaved weeds.
At all the stages of observation, density and dry matter production of
grasses, sedges, broad leaved weeds and total of all category of weeds recorded
xix
the lowest with 100 kg ha-1 nitrogen application, where as the highest values
were associated with 160 kg N ha-1, which was comparable with 140 kg N ha-1.
The pre emergence application of oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS
recorded the lowest density and dry matter production of grasses. PE application
of pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at 25 DAS recorded lowest
density and dry matter production of broad leaved weeds. PE application of
oxadiargyl @ 75 g a.i ha-1 or pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at 25
DAS were comparable with each other in reducing density and dry matter
production of sedges. The pre emergence application of oxadiargyl @ 75 g a.i
ha-1 fb HW at 25 DAS recorded the lowest density and dry matter production of
total weeds. The highest density and dry matter production of all the categories
of weeds were associated with un-weeded check. Nitrogen levels did not exert
any significant influence on WCE, where as the influence of different weed
management practices on WCE followed exactly the similar trend of total density
and dry matter production of weeds.
The lowest uptake of nutrients by weeds was obtained with 100 kg N ha-1,
while the highest was noticed with 160 kg ha-1. The lowest nutrient uptake by
weeds was recoded with pre emergence application of oxadiargyl @ 75 g a.i ha-1
fb hand weeding at 25 DAS, which was comparable to PE application of
pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at 25 DAS, where as the highest was
recorded with un-weeded check.
The highest gross and net returns including benefit-cost ratio were
realized with 140 kg N ha-1, which was comparable to 160 kg N ha-1
. Pre
emergence application of oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS recorded
the highest gross and net returns, where as PE application of pyrazosulfuron
ethyl @ 20 g a.i ha-1 fb HW at 25 DAS resulted in highest benefit-cost ratio and
these were in turn comparable with each other in recording higher economic
returns. The lowest gross and net returns with lower benefit - cost ratio were
realized with un-weeded check.
Increasing levels of nitrogen supply enhanced the post harvest soil
available nitrogen up to the highest level 160 kg ha-1, where as the highest soil
available phosphorus and potassium were recorded with 140 kg N ha-1 and these
were in turn comparable with each other. Pre emergence application of
oxadiargyl @ 75 g a.i ha-1 fb HW at 25 DAS resulted in the highest soil available
nitrogen, phosphorus and potassium, which was comparable with PE application
of pyrazosulfuron ethyl @ 20 g a.i ha-1 fb HW at 25 DAS, while the lowest
values of post harvest soil nutrient status was noticed with un-weeded check.
In conclusion, the study revealed that the higher grain yield and quality of
aromatic rice with maximum economic returns were achieved with combination
of nitrogen application 140 kg ha-1 and pre emergence application of oxadiargyl
@ 75 g a.i ha-1 fb HW at 25 DAS, which was however, comparable with the
same level of nitrogen and PE of pyrazosulfuron ethyl @ 20 g ha-1 fb HW at 25
DAS. Quality parameters were not much affected by the weed management
practices except milling per cent and protein content of grain under aerobic
culture.
 
Date 2016-06-16T15:18:32Z
2016-06-16T15:18:32Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67481
 
Language en
 
Relation D9340;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY