iv result & dis pravir

7/31/2019 IV Result & Dis Pravir

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CHAPTER IV

RESULTS AND DISCUSSION

The experiment was conducted during kharifseason (June to November) 2011,

to find out the suitable weed management practices for scented rice cultivation. The

experimental findings have been thoroughly discussed and interpreted in this chapter

through proper reasoning and reviews along with appropriate headings, tables and

figures.

4.1 Weather conditions

The weather data recorded during the experimental period are presented in

Appendix-I and depicted through Fig 3.1. The crop received 1193.7 mm rainfall during

entire growth period. The maximum temperature during crop period varied from 33.4

C in the first week of July to 28.3 C in the first week of September, while minimum

temperature ranged between 15.2 C in the fifth week of October to 25.8C in the fifth

week of July. Relative humidity throughout the crop season varied between 27 to 96

per cent. The average maximum relative humidity for different weeks varied from 88 to

94.25 percent, while, weekly average minimum relative humidity varied between 29 to

78.75 percent. The open pan evaporation mean values ranged from 3.42 to 4.34 mm

day1, whereas, average sunshine hours varied from 2 to 8.05 hours day-1. The average

wind velocity for different weeks varied from 0.85 to 11.00 km hr1.Thus all weather

ingredients were favourable during crop growth period.

No severe incidence of diseases and insects were observed during the crop

growth period. Thus, whatever variations observed in the various characters studies


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within the investigation are attributed to different treatments exercised in this

experiment.

4.2 Pre-harvest observations on crop

4.2.1 Plant population (m-2)

Plant population of rice recorded during initial and harvest stages as affected

by weed control treatments have been presented in Table 4.1. Results showed that

significantly lowest plant population (viz. 25.00 and 24.33 at 20 DAT and harvest,

respectively) was observed in treatment T2 where space transplanting (20 cm x 20 cm)

was done. Treatment T8 resulted in significantly higher plant population (66.33 and

65.65 plants m-2 at 20 DAT and harvest respectively) mainly due to planting of rice

in closer row spacing (15 cm x 10 cm). On the other hand weed control treatments

did not caused much variations in plant population both at 20 DAT and at harvest

stages.

Table 4.1 Plant population of rice (m-2) as influenced by various weed

management treatments

Treatments Plant population (m-2)

20 DAT Harvest

T1-Weedy check(20x10 cm) 49.67 48.00

T2-Use of cono weeder (20x20 cm) 25,45 DAT 25.00 24.33

T3-1 H.W (20x10 cm) 25 DAT 49.00 48.33

T4-2 H.W (20x10 cm) 25,45 DAT 50.00 49.00

T5-Acetic acid (20%)(20x10 cm) 25,45 DAT 49.00 48.67T6-Ambika paddy weeder(20x10 cm) 25,45 DAT 50.00 49.00

T7-Burn oil spray + 1 HW (20x10 cm) 15,30 and

45 DAT

50.00 48.67

T8-Closer row spacing at (15x10 cm) 66.33 65.65

SEm+ 0.35 0.30

CD 5 % 1.06 0.89


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4.2.2 Plant height (cm)

Plant height is one of the important growth parameters of any crop plant as it

determines or modifies the yield contributing characters and finally shapes the grain

yield. The analyzed data presented in Table 4.2 revealed that, on an average, plant

height increased with the advancement of crop duration and its value ranged from

43.19 to 129.86 cm depending on crop stage and weed control method used. The

increment in plant height was most intensive between 20 and 40 DAT. Compared to

weedy check treatments. Plant height was significantly influenced by all weed control

methods between 40 DAT till harvest stage of crop growth.

At 20 DAT, none of the weed management methods influenced the plant height of rice

significantly. At 40 DAT, mechanical weeding through ambika paddy weeder had

produced significantly taller plants (96.28 cm), while the unweeded check plots

produced significantly shorter plants 83.81 cm. The same pattern was observed at 80

DAT and at harvest stages. With regards to manual weeding, rice plant attains

maximum plant height with two weeding, being significantly higher over that recorded

in other treatments except with mechanical weeding. The increment in plant height

resulting from ambika paddy weeder (T6) over weedy check treatment was 15% at

harvest. Use of mechanical weeder brought significant growth in plant height owing

due to the reason that mechanical weed control results in better soil aeration and

greater root and shoot development. Incorporation of weed with mechanical weeder

increased the root activity which stimulated the new cell division in roots by pruning

of some upper roots encouraged deeper root growth thereby increased the shoot:root

ratio (Uphoff, 2001). Vijayakumar et al.,(2006) also point out that mechanical


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weeding could enhance plant height by better soil aeration and incorporation of weeds

as a green manure increased the organic carbon content of the soil.

Table 4.2: Plant height (cm) of rice at different growth stages as influenced by

various weed management treatments

Treatments Plant height (cm), DAT20 40 80 Harves

tT1-Weedy check(20x10 cm) 38.19 83.81 97.67 112.98

T2-Use of cono weeder (20x20 cm) 25,45

DAT39.24 94.67 121.52 125.92

T3-1 H.W (20x10 cm) 25 DAT 38.32 85.21 116.56 120.44

T4-2 H.W (20x10 cm) 25,45 DAT 39.34 86.54 120.63 124.86

T5-Acetic acid (20%)(20x10 cm) 25,45

DAT39.65 87.48 117.37 118.24

T6-Ambika paddy weeder(20x10 cm) 25,45

DAT38.25 96.28 125.32 129.7

T7-Burn oil spray + 1 HW (20x10 cm)

15,30 and 45 DAT39.60 84.56 116.30 119.98

T8-Closer row spacing at (15x10 cm) 39.87 88.42 113.91 117.84

SEm+ 0.28 1.08 1.17 1.04

CD (5%) NS 3.31 3.48 3.18

4.2.3 Number of tillers (m-2)

Tillering plays a vital role in determining rice grain yield since it is closely

related to number of panicle per unit ground area. Too few tillers result in too few

panicles, but excess tillers enhance high tiller mortality, small panicles, poor grain

filling, and consequent reduction in grain yield (Peng et al.,1994).

The mean value of the number of tillers (m-2) in the experiment for all treatment

(Table 4.3) indicated that increase in number of tillers per plant between 20 and 80

DAT was remarkable. The maximum tiller production reached at 80 DAT (496.67)

and gradually declined at later growth stages. The decrease in the number of tillers per

plant was attributed to the death of some of the last tillers as a result of their failure in

competition for light and nutrients (Fageria, et al.,1997b). Another explanation for this


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effect is that during the panicle initiation stage of crop growth period, competition for

assimilates exists between developing panicles and young tillers. Eventually, growth

of many young tillers is suppressed, and they may senesce without producing seed

(Dofing and Karlsson, 1993). The number of tillers per square meter was significantly

influenced by weed control methods at all the dates of observation except at 20 DAT.

The lowest number of tillers (viz. 284.67, 410.33 and 358.67 m-2 at 40 DAT, 80 DAT

and at harvest respectively) was observed in no weeding (weedy check) which was

significantly inferior than those observed in other weed control treatments. At 40

DAT, the highest number of tillers (334.67 m

-2

) was produced with the use of cono-

weeder (T2) which stand on a par with weeding performed by Ambika paddy weeder

(331.67 m-2) and both of these treatments produced significantly higher number of

tillers than rest of the weed control treatments. Similar pattern of maximum tillering

was observed at 80 DAT and harvest stages. Next to mechanical weeding, two manual

weeding at 25 and 45 DAT produced significantly higher number of tillers during all

the stages of observations compared to other methods of weed control used.

Vijaykumar et al. (2006) also opined that mechanical weeding not only helped in

reducing the weed competition, but also improved root growth by increasing soil

aeration and root pruning which ultimately resulted in increased number of tillers per

plant (Shad, 1986). Results of this study showed that weed free condition was best for

tiller production. Weedy check treatment or ineffective methods of weed control failed

to produce more tillers due to severe weed infestation in the experimental plot.

Table 4.3: Total number of tillers (m-2 ) of rice at different growth stages

influenced by various weed management treatments


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Treatments No. of tillers (m-2) at No. ofeffectivetillers m-2

20DAT

40DAT

80DAT

Harvest

T1-Weedy check(20x10 cm) 187.0

0

284.6

7

410.3

3

358.6

7

346.67

T2-Use of cono weeder (20x20

cm) 25,45 DAT187.6

7334.6

7495.6

7489.6

7477.67

T3-1 H.W (20x10 cm) 25 DAT 188.67

324.67

398.33

385.33

376.33

T4-2 H.W (20x10 cm) 25,45DAT

187.67

322.00

484.67

481.67

471.33

T5-Acetic acid (20%)(20x10cm) 25,45 DAT

188.67

305.33

478.67

457.67

437.67

T6-Ambika paddyweeder(20x10 cm) 25,45

DAT

189.00

331.67

496.67

486.67

470.67

T7-Burn oil spray + 1 HW

(20x10 cm) 15,30 and 45

DAT

187.67

310.00

454.33

439.33

423.67

T8-Closer row spacing at (15x10

cm)

189.00

290.00

412.33

388.33

367.33

SEm+ 0.59 2.03 1.43 2.23 1.66CD (5%) NS 6.13 4.32 6.77 5.04

4.2.4 Number of effective tillers (m-2)

Grain yield of cereals is highly dependent upon the number of effective tillers

produced by each plant (Nerson, 1980). According to the data presented in Table 4.6,

the average number of effective tillers per square meter across all treatment was

ranges from 346.67 to 477.33 depending on weed control method used. In general, the

number of effective tillers per square meter was significantly increased by all the weed

management practices used in this investigation compared to weedy check, however,

their efficacy varied depending upon their ability to control the composite population

of weeds. The treatment of weeding through cono-weeder produced significantly

maximum number of effective tillers (477.67 m-2) compared to any other methods of

weed control. Proper control of weeds reduced the weed density which facilitates the


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crop plants to have sufficient space, light, nutrient and moisture, and thus the effective

tillers increased (Hasanuzzaman et al. 2009). Weedy check (T1) resulted in minimum

number of effective tillers (346.67 m-2), being significantly lower than all the weed

control treatments. This might be due to the fact that the higher competition of weeds

did not allow the rice plant to produce more number of effective (panicle bearing)

tillers in the unweeded treatment. Among the various weed control treatments, closer

row spacing gave minimum effective tillers due to inter plant competition for longer

period which inhibited the plants to produce tiller. Uprety (2005) stated that early

weeding enhances production of more primary tillers, which ultimately produces

larger panicles having more grains and higher yield.

4.2.5 Dry matter accumulation (g hill-1)

The dry matter production per unit area is the prerequisites for higher

production. The amount of dry matter production depends on the effectiveness of

photosynthesis of the crop which in turn depends on large and efficient assimilating

area for adequate supply of solar radiation and carbon dioxide and favorable

environmental condition.

Table 4.4: Dry matter accumulation (g hill-1) of rice at different growth stages

influenced by various weed management treatments


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Treatments Dry matter accumulation (ghill-1)20DAT

40DAT

80DAT

Harvest

T1-Weedy check(20x10 cm) 3.48 6.72 34.77 47.86T2-Use of cono weeder (20x20 cm) 25,45

DAT3.48 9.65 53.26 68.44

T3-1 H.W (20x10 cm) 25 DAT 3.76 7.62 35.83 47.90T4-2 H.W (20x10 cm) 25,45 DAT 3.64 9.58 45.62 61.63T5-Acetic acid (20%)(20x10 cm) 25,45

DAT

3.51 7.76 41.26 55.30


DAT

3.64 9.10 51.57 66.00


15,30 and 45 DAT3.09 7.55 36.44 49.71

T8-Closer row spacing at (15x10 cm) 3.14 8.26 35.88 48.94SEm+ 0.23 0.26 0.47 0.45CD (5%) NS 0.81 1.43 1.37

The dry matter production (g hill-1) determined at 20, 40, 80 days after

transplanting and at harvest are presented in Table 4.4 and depicted through Fig.

Analysis of results indicated that all the weed management treatments caused

significant variations in DM production compared to weedy check, however their

efficacy varied depending upon their ability to suppress the weed growth. Normally

dry matter accumulation in rice plant increased upto 80 DAT and after that it declined

due to tiller mortality, but it was not true in our experimentation which might be due to

a wide gap existed in between 80 DAT and last observation recorded at harvest.

Although the variation was non-significant at an early growth stage (20 DAT),

however, distinct differences were visible among the weed control treatments in DMA

at 40 DAT and onwards until the end of season. Finally, the higher DM production of

9.65, 53.26 and 68.44 g hill-1 of rice at 40, 80 DAT and at harvest, respectively was

recorded through T2 treatment (mechanical weeding with cono-weeder), while the


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lowest DM production was observed under weedy check (T1). Though the DM

production under manual weeding (T4) and weeding through ambika paddy weeder

(T6) remained on a par but both of these treatment achieved significantly higher dry

matter production compared to rest of weed management practices other than T2

treatments. The increase in DMA was owing to significant increase in plant height and

tiller production as well as reduction in density and dry weight of weeds which restrict

their ability to restrict their ability to compete with the crop for different growth

factors resulting into better expression of dry matter accumulation. Similar results

have been reported by Ali et al.(2008).

4.2.6 Crop growth rate (g day-1 hill-1)

The data on crop growth rate (CGR) at various stages of crop as influenced by

various weed management practices are presented in Table 4.5 and depicted in Fig.

4.2. Results indicated that irrespective of treatments effect, crop growth rate enhanced

sharply up to 80 DAT and thereafter it declined. Therefore, growth period in between

40 to 80 days after transplanting appeared to be critical for maximum growth and

development of rice crop.

Table 4.5: CGR (g day-1 hill-1) of rice at different growth stages influenced by

various weed management treatments


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Treatments CGR (g day-1 hill-1)20-

40DAT

40-

80DAT

80-

Harvest

T1-Weedy check(20x10 cm) 0.16 0.70 0.32

T2-Use of cono weeder (20x20 cm) 25,45DAT

0.31 1.1 0.38

T3-1 H.W (20x10 cm) 25 DAT 0.19 0.70 0.30T4-2 H.W (20x10 cm) 25,45 DAT 0.30 0.90 0.40T5-Acetic acid (20%)(20x10 cm) 25,45

DAT0.21 0.83 0.35


DAT0.27 1.0 0.36


15,30 and 45 DAT0.22 0.72 0.33

T8-Closer row spacing at (15x10 cm) 0.25 0.69 0.32

SEm+ 0.03 0.02 0.03CD (5%) NS 0.07 NS

The crop growth rate from 20-40 DAT of rice did not varied significantly due

to weed control treatments. However, numerically lowest CGR was recorded in weedy

check (T1) treatment while weeding performed through ambika paddy weeder (T6)

resulted in highest CGR. At 40-80 DAT, all the weed control treatment contributed to

the superior CGR over the weedy check and treatment mechanical weeding through

cono-weeder (T2) gave the highest CGR (1.1 g day-1) which were statistically similar

to mechanical weeding done by ambika paddy weeder (T6) and both of these

mechanical weedings remained significantly superior over other treatments. Similar

trend of CGR at 80-harvest period was noticed but treatment effects could not reach to

the level of significance. Results indicated that heavy weed infestation in the weedy

check (no weeding treatment) might have hampered the normal growth and

development of rice plants and ultimately poor dry matter accumulation which in turn


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reduced the CGR compared to all the weed control treatments. The results confirm the

findings of Ali et al., (2008)

4.3 Weed infestation studies

4.3.1 Weed density

The data on weed density at various stages of crop growth as influenced by

methods of weed control are presented in Table 4.6 and depicted in Fig... On an

average, the weed density varied from 7.51 to 23.11 m-2 depending upon the stage of

crop and weed control method. The weed density was significantly influenced by

weed control treatments during all the stages of observation. All the weed

management treatments brought down weed densities significantly as compared to that

in untreated check( 23.11 m-2). and later treatment recorded the highest weed

population (viz. 10.06, 15.87, 20.95 and 23.11 m-2 at 20, 40, 80 DAT and at harvest

respectively) compared to all methods of weed control. At 20 DAT, weed density did

not varied significantly due to methods of weed control followed, however higher

weed density (10.06 m-2) was recorded in weedy check plot (T1) and lower weed

density (7.51 m-2) from closed row spacing which might be due to maximum spaced

occupied by rice plants leaving minimum ground for growing weed plants. Since,

manual and mechanical weed treatments was accomplished at 25 DAT onwards, hence

variation in weed density due to these treatments remained non-significant. At 40

DAT, weed density was minimum (7.23 m-2) in hand weeded plot (T3) which was on

par with T4, T6 and T8 treatments. Since second hand and mechanical weeding was

performed at 45 DAT, hence their effect on weed suppression was not visualized at the

time of observation made at 40 DAT. At 80 DAT, mechanical weeding through


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ambika paddy weeder resulted in least weed density of 6.99 m-2 which was on a par

with that recorded in treatment of cono-weeder and both of these treatment

significantly excelled over other methods of weed control. Similar trends of weed

density was noticed at harvest. Similar findings was also reported by Rekha et al.,

(2002) that weed density was lower in all treatments compared to the unweeded

control plot.

Table 4.6: Weed density (m-2) in rice field as influenced by different weed

management treatments

Treatments Density of weeds (m-2)20DAT

40DAT

80DAT

Harvest

T1-Weedy check(20x10 cm) 10.06 15.87 20.95 23.11


9.24 8.38 6.75 7.34

T3-1 H.W (20x10 cm) 25 DAT 10.21 7.23 13.95 14.13

T4-2 H.W (20x10 cm) 25,45 DAT 9.48 7.56 8.69 9.14

T5-Acetic acid (20%)(20x10 cm) 25,45

DAT

9.68 12.59 14.96 15.13


DAT

9.28 7.74 7.89 6.99


15,30 and 45 DAT

8.23 13.44 13.22 12.77


SEm+ 0.10 0.19 0.24 0.24

CD (5%) NS 0.60 0.72 0.73

4.3.2 Weed dry weight (g m-2)


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Data on weed dry weight (g m-2) recorded at different growth stages of rice

are presented in Table-4.7 and illustrated in Fig. Results revealed that considerable

differences in weed dry weight existed between 20 DAT to harvest stage of rice

depending upon the methods of weed control used. Among the different treatments,

weedy check (T1) resulted in highest weed dry weight (8.98, 14.34, 1945 and 24.36 g

m-2 at 20, 40, 80 DAT and harvest respectively) as compared to weed control

treatments. Singh and Kumar (1999) also expressed that maximum weed dry weight

was recorded in the unweeded control which was significantly higher compared to

other weed control treatments. During initial stage of crop growth, significantly

minimum weed dry weight (6.19 g m-2) was observed in the treatment of closer row

spacing (T8) which was on par with T5 and T7 treatments. Other mechanical and hand

weeding treatments did not cause significant variation in weed dry weight because

these treatments were applied 25 days after transplanting of rice.

Table 4.7: Weed dry weight (g m-2) at various stages of crop growth as influenced

by different weed management treatments

Treatments Weed dry weight (g)20DAT

40DAT

80DAT

Harvest

T1-Weedy check(20x10 cm) 8.98 14.34 19.45 24.36


7.98 4.87 7.16 8.35

T3-1 H.W (20x10 cm) 25 DAT 8.90 5.29 8.81 12.14

T4-2 H.W (20x10 cm) 25,45 DAT 8.40 5.62 7.34 10.95

T5-Acetic acid (20%)(20x10 cm) 25,45

DAT

6.59 9.77 10.68 14.11


DAT

7.86 5.01 7.628.33

T7-Burn oil spray + 1 HW (20x10 cm) 6.61 11.37 12.90 13.79


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15,30 and 45 DAT


SEm+ 0.38 0.20 0.13 0.21

CD (5%) 1.01 0.62 0.42 0.64

At 40 DAT, the highest weed dry weight (14.34 g m-2) was recorded at unweeded

check treatment (T1) which was significantly greater over all weed control treatments.

Significantly lowest weed biomass (4.87 g m-2) was recorded in T2 (cono-weeder)

treatment but it was at par with the values obtained under manual weedings (T3 and

T4) and soil aerating weeding (T6) treatments. Similar trends of weeds dry weight

were displayed during later stages of crop growth. The minimum dry weed biomass in

mechanical or hand weeded plots was due to the reason that first and second flush of

weeds was suppressed critically and later the regenerated weeds could not compete

with the crop when the crop plants attained a reasonable height during 40 DAT to

harvest stages.

4.3.3 Weed control efficiency

Results indicated that weed control efficiency of different weed control

practices had decisive bearing on weed density and weed biomass leading to better

weed control efficiency, which was ultimately manifested in better grain yield. The

higher was the WCE, the lower was the weed density as well as weed biomass ( Table-

4.8 ). The ultimate impact was the higher yield (Table yield). At 20 DAT, the highest

weed control efficiency was achieved in the treatment of acetic acid (20%) because of

suppression of weed growth during initial stage of crop growth. Mechanical weeding

through cono-weeder resulted in maximum weed control efficiency of 66.04 and


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63.18 % during 40 and 80 DAT respectively. However, at harvest stage of crop

growth, mechanical weeding by ambika paddy weeder numerically recorded

maximum WCE closely followed by weeding with cono-weeder. Hand weeding

treatments stand next to mechanical weeding in terms of increasing weed control

efficiency. Mechanical and manual weeding enhanced weed control efficiency due to

restricted weed growth, resulted in lower dry matter production of weeds which in turn

resulted in higher weed control efficiency.

Table 4.8: Weed control efficiency at various growth stages of rice as influenced

by methods of weed control.

Treatments WCE20 40 80 Harves

tT1-Weedy check(20x10 cm) - - - -

T2-Use of cono weeder (20x20 cm) 25,45

DAT

11.13

66.04 63.18 65.72

T3-1 H.W (20x10 cm) 25 DAT 0.89 63.11 54.70 50.16

T4-2 H.W (20x10 cm) 25,45 DAT 6.45 60.81 62.26 55.05T5-Acetic acid (20%)(20x10 cm) 25,45

DAT26.6

131.86 45.08 42.07


DAT

12.47

65.06 60.82 65.80


15,30 and 45 DAT

12.47

20.71 33.67 43.39

T8-Closer row spacing at (15x10 cm) 31.06

24.06 33.77 42.56

4.4 Post harvest observations

4.4.1 Panicle length (cm)

Having a direct bearing on vegetative growth, the reproductive growth is the

ultimate aim of farmers and scientists alike. The data on panicle length of rice as


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influenced by various weed control treatments are presented in Table 4.9. Results

revealed that length of rice panicles varied significantly due to the influence of

treatments under study. The unweeded check treatment produced significantly lowest

length of panicle (27.74 cm) over that observed with mechanical and hand weeding

treatments but stand on par with remaining weed control treatments (T5,T7 and T8).

The lowest length of panicle might have resulted due to higher competition of weeds

with the crop plants failed to produce the normal growth of panicles. Similar

observation was also reported by other workers Attalla and Kholosy, 2002 and Ahmad

et al., 2008) where weed control treatments significantly enhanced the panicle length.

Greater weed infestation in unweeded check might had resulted in shortest panicle

length among the weed control treatments. The mechanical weeding through cono-

weeder significantly excelled all other treatments by producing lengthier panicles

(32.44 cm) over rest of the weed control treatments. Rice crop provided with two hand

weeding (T4) and weeding through ambika paddy weeder was found to be next

superior in terms of producing longer panicles.

Table 4.9: Yield-contributing characteristics of rice as influenced by various

weed management treatments

Treatments Panicle

length, cm

Test

weight, g

Total

spikelets

panicle-1

No. of

grains

panicle-1

Sterility

% age

T1-Weedy check(20x10cm)

27.74 27.70 105.30 77.00 36.75

T2-Use of cono weeder(20x20 cm) 25,45 DAT

32.44 30.85 152.67 135.60 12.58

T3-1 H.W (20x10 cm) 25

DAT

29.53 27.96 126.67 104.34 21.40

T4-2 H.W (20x10 cm) 31.39 30.24 145.00 128.76 12.61


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25,45 DAT

T5-Acetic acid (20%)

(20x10 cm) 25,45 DAT

28.31 29.48 137.30 102.00 34.61

T6-Ambika paddy

weeder(20x10 cm)

25,45 DAT

30.96 30.08 144.30 126.68 13.91

T7-Burn oil spray + 1 HW

(20x10 cm) 15,30 and45 DAT

28.72 28.07 132.00 98.60 33.87

T8-Closer row spacing at

(15x10 cm)

27.99 28.00 128.30 107.98 18.82

SEm+ 0.41 0.27 1.19 1.01 1.05

CD (5%) 1.27 NS 3.60 3.05 3.19

4.4.2 Total spikelets panicle-1

Data on total number of spikelets as influenced by various weed control

treatments are shown in Table 4.9. The weed control treatments significantly affected

the total number of spikelets per panicle. Unweeded control treatment (T1) resulted in

the lowest number of spikelets (105.30 panicle-1), being significantly inferior over all

weed control treatments. Comparing different weed control treatments, it can be

inferred that mechanical weeding through cono-weeder (T2) resulted in highest

number of spike lets (152.67 panicle-1), which was significantly different from other

weed control tactics used in this investigation. Hand weeding twice and mechanical

weeding through ambika paddy weeder came out to be next best treatments (with

145.00 and 144.3 spike lets panicle-1) after T2 treatment in terms of spike lets

production. In the treatments where weeds were controlled effectively, there total

number of spikelets panicle-1

recorded higher because weeds did not pose competition

with the rice plant for nutrients, water, light, etc. The result further indicated that

greater weed infestation in the unweeded control and ineffective weed control resulted

in the lower number of spikelets per panicle. Similar results were also reported by


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Attalla and Kholosy (2002). In an another studies, Sultana (2000) found that there

were 40 % reduction of grains per panicle due to competition ofE.crussgalli and 28.7

% reduction due to competition ofE.colonum at a density of 200 weeds m-2.

4.4.3 Number of grains panicle-1

The number of grains panicle-1 as influenced by different by weed control

treatments are presented in Table 4.9. Results demonstrated that all weed control

treatments caused the increment of number of grains per panicle over weedy check

treatment. Thus, lowest number of grains (77.00 panicle-1) was observed in the

unweeded check (T1) which was significantly inferior to other treatments. Mechanical

weeding through cono-weeder maintained its superiority in terms of maximum

number of grains (135.60 grains panicle-1) which was proved to be significantly

superior over other treatments. Hand weeding twice and mechanical weeding through

ambika paddy weeder resulted in next higher number of grains (128.76 and 126.68

grains panicle-1) compared to other weed control methods. This might be due to higher

crop-weed competition in the weedy check and other treatment where weeds growth

was not suppressed effectively, as weeds shared with the crop for its nutrients, water,

light or other necessary growth factors and consequently reduced grains panicle -1.

These results are in accordance with the findings of Vijaykumar et al. (2006) who

reported that use of mechanical weeding resulted in higher nutrient availability

subsequently resulting in a better source to sink conversion which enhanced higher

number of grains per panicle.

4.3.4 Test weight (g)


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The test weight is a stable varietal character because the grain size is rigidly

controlled by the size of the hull (Yoshida, 1981). Data on test weight of rice as

influenced by different weed control methods are presented in Table 4.9. Results

revealed that test weight of rice were not significantly influenced by weed control

treatments, althooough they numerically differed among themselves. These results

corroborated with the findings of Islam et al.(2003) and they reported that no

significant difference in 1,000 grain weight was found between weed free and weed

competition levels. The average test weight was 29.04g in the experiment as a whole,

ranging between27.70 to 30.85 g depending upon the weed control methods used.

Weedy check (T1) produced very light weight seeds (27.70 g) while mechanical

weeding through cono-weeder (T2) resulted in heavier test weight (30.85 g) but

differences between them was not significant. Similar line of results were also

reported by Ahmed et al.,(2008).

4.3.5 Sterility percentage

The data on sterility percentage (Table 10) showed that it varied significantly

due to the effect of weed control treatments. The average serility percentage observed

in the experiment as a whole was23.06 %, and ranged from12.58 to 36.75 %

depending upon the weed control treatment. The highest sterility percentage (36.5 %)

was observed in the unweeded check (T1) which was significantly higher than those of

other treatments. The lowest sterility (12.61 %) was observed in a treatment of two

hand weeding (T4), being at par with that found (12.58 %) in the treatment where

mechanical weeding was carried out by cono-weeder (T2) and both of these treatments

registered their statistical superiority over other treatments. Weed infestation perhaps,


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the main reason for such variation of the sterility in different treatments. Weedy check

or the treatments where weed control was inadequate there sterility per cent was high

because weeds compete with the rice plant for nutrients, water, light and other growth

factors and consequently had adverse effect on the grain formation and caused the

higher sterility percentage. The results corroborate the findings of Ahmed et al.,

(2008).

4.3.6 Grain yield (q ha-1)

Grain production, which is the final product of growth and development, is

controlled by dry matter accumulation during ripening phase (De Datta, 1981). Data

pertaining to grain yield of rice as influenced by various weed control treatments are

presented in Table 4.11 and depicted in Fig.. Results indicated that grain yield of

rice showed marked variations due to weed control methods adopted in this

investigation. The rice grain yield in general was found to range from 26.39 to35.68

qha-1 depending upon methods of weed control followed. Weedy check (T1) resulted

significantly lowest grain yield (26.39 q ha-1) compared to all methods of weed control

due to increased crop-weed competition higher weed dry weight, lowest number of

effective tillers m-2 and test weight and this was somewhat similar with the observation

of Phogat et al.(1998). This indicates that heavy weed infestation has caused a

substantial reduction in the yield of rice.

Mechanical weeding through cono-weeder (T2) resulted in significantly

highest grain yield over that recorded with other treatments. This was closely followed

by mechanical weeding through ambika paddy weeder and two hand weeding which

gave 34.69 and 3.29 q grain yield ha-1, being significantly superior over other methods


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of weed control except weeding done by cono-weeder. Two soil aerating

weeding(cono weeder) increased grain yield by 35.20% over unweeded check

treatment. Higher grain yield from mechanical weedings might be due to less weeds

competition, lower weed density ( 7.34 m-2), lower dry weight of weeds (8.35 g m-2)

and higher weed control efficiency(65.72%) resulted by better weed control under this

treatment. Vijaykumar et al.(2006) also reported that incorporation of weeds through

by mechanical weeder recorded the higher grain yield. However, Mukhopadhyay

(1983) stated that hand weeding is the most common method and two weedings are

sufficient to adequately control weeds in transplanted rice. Our findings have the

implication that if labour availability is a limiting factor, the mechanical weeding

could be another suitable alternative for efficient weed management in transplanted

scented rice.

4.3.7 Straw yield (q ha-1)

Analysis of the data presented in Table 4.11 showed that straw yield of rice

differed significantly due to application of weed control treatments. An average straw

yield of 69.61 q ha-1 was recorded across the experimental trials, ranging from 64.53

to 73.88 q ha-1 Straw yields all weed control treatments were significantly higher as

compared to that of untreated check (T1). Thus, lowest straw yield (64.53 q ha-1) was

observed in the unweeded check treatment because of severe weed infestation that

hampered the plant height and also its tillering capacity which in turn reduced the

straw yield. The mechanical weeding accomplished through cono-weeder (T2)

produced the highest straw yield (73.88 q ha-1) and it was identical with treatment T6

(71.27 q ha-1) and superior to all other weed control treatments. Other methods of


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weed control proved significantly better than weedy check but they did not caused

significant variations among themselves in terms of straw production. The increase in

rice straw yield with efficient weed control treatment may be attributed to better crop

growth in the absence of weed-crop competition for any of the growth factor. Rice

plant without such competition recorded higher plant height, tillers m-2 and CGR over

weedy check because of the greater space captured by rice plants. Ahmed et al.,(2008)

also reported the highest straw yields ha-1 from weed free plot and the lowest from no

weeding plots.

4.3.8 Harvest index

Grain yield in cereals is related to biological yield and grain harvest index

(Donald and Hamblin, 1976). Data on harvest index of rice as influenced by different

weed control treatments are presented in Table 4.11. Results exhibited that harvest

index was significantly different among weed control methods. Weedy check (T1)

treatment resulted in significantly lowest harvest index (29.02) over all weed control

treatments which was statistically inferior to rest of the treatments. On the other hand

the highest harvest index (32.73) was observed in the treatment where mechanical

weeding was done through ambika paddy weeder (T6) which was statistically identical

to that produced by T2 (32.57) and T4 (32.23) treatments. All these three treatments

were found to be significantly superior over other weed control treatment. The HI

values recorded in other weed control treatments remained at par among themselves.

Heavy weed infestation in turn more weed-crop competition in unweeded check (T1)

and inadequate weed control treatments reduced the grain yield which ultimately

affected the harvest index. Similar observation also reported by Ahmed et al.,(2008)


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through cono weeder. As regards to rice grains none of the parameters influenced

significantly due to weed control treatments. Thus, it could be concluded that grain

quality remained unaffected due to weed control treatments.

Table 4.11: Length and breadth of paddy and rice grains as influenced by various

weed management treatments

Treatments Paddy grains Rice grainsLength

Breadth

L/B Length

Breadth

L/B

T1-Weedy check(20x10 cm) 9.10 2.10 4.37 7.07 1.50 4.72T2-Use of cono weeder

(20x20 cm) 25,45 DAT 10.57 2.27 4.67 7.93 1.93 4.11

T3-1 H.W (20x10 cm) 25DAT 9.70 2.13 4.54 7.67 1.57 4.92

T4-2 H.W (20x10 cm) 25,45 DAT 10.33 2.23 4.63 7.87 1.90 4.15

T5-Acetic acid (20%)(20x10cm) 25,45 DAT 10.10 2.20 4.60 7.73 1.87 4.14

T6-Ambika paddy

weeder(20x10 cm) 25,45DAT 10.27 2.20 4.67 7.83 1.87 4.20

T7-Burn oil spray + 1 HW(20x10 cm) 15,30 and 45

DAT 10.07 2.20 4.58 7.73 1.67 4.65T8-Closer row spacing at

(15x10 cm) 9.97 2.17 4.61 7.70 1.60 4.82SEm+ 0.24 0.06 0.19 0.10 0.05 0.12CD (5%) NS NS NS NS NS NS

4.5 Economics of treatments

Farmers resources such as land, labour and capital are important

considerations in making the final choices of weed control method ( De Datta and

Barker, 1977). The economical analysis of various treatments under investigation

was worked out and presented in the Table 4.12 to evaluate the most beneficial


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and economical treatment for the cultivation of scented rice. The details of fixed

cost and cost of various weed control treatments are given in Apendix-II and III,

respectively.

Table 4.12: Economics of various weed management treatments in rice

cultivation

Treatment Fixed

cost

Treatment

cost

Total cost

ofcultivation

(Rs ha-1)

Gross

return

(Rs ha-1)

Net

return

(Rs ha-1)

Benefit:

cost

ratio

Grain

yield

Straw

yield

T1-Weedycheck(20x10

cm)

21259.3 600 21859.3 29292.9 6453 13886.6 0.63

T2-Use of

cono weeder

(20x20 cm)

25,45 DAT

21259.3 4713.92 25973.22 39604.8 7388 21019.58 0.80

T3-1 H.W

(20x10 cm) 25 DAT

21259.3 3752.8 25012.1 34920.6 7011 16919.5 0.67

T4-2 H.W

(20x10 cm) 25,45 DAT

21259.3 6905.6 28164.9 36951.9 6997 15784 0.56

T5-Acetic acid

(20%)(20x10

cm) 25,45

DAT

21259.3 11715.28 32974.58 33788.4 6861 7674.82 0.23

T6-Ambika

paddyweeder(20x10

cm) 25,45

DAT

21259.3 3752.8 25012.1 38505.9 7127 20620.8 0.82

T7-Burn oil

spray + 1 HW(20x10 cm)

15,30 and 45

DAT

21259.3 15811.92 37071.22 33499.8 6989 3417.58 0.09

T8-Closer row

spacing at

(15x10 cm)

21259.3 799.95 22059.25 33288.9 6866 18095.65 0.82


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4.5.1 Cost of cultivation

The data (Table 4.12 ) showed that, in general treatment T7-Burn oil spray + One

H.W. required higher cost of cultivation per hectare while unweeded check plot

required the lower cost of cultivation.

4.5.2 Gross return

Economic analysis (Table 4.12 ) revealed that average gross return was Rs

41943.15 per hectare and it ranging from to Rs 35745.9 to Rs 46992.8per hectare

depending up on weed control methods used. All weed control treatments came up

with higher gross return over weedy check. The higher gross return (Rs 46992.8/ha)

was found under treatment T2-Use of Cono-weeder and lowest (Rs 3574.9/ha) was

noted in unweeded check plot.

4.5.3 Net return

The analyzed data (Table 4.12 ) indicated that the average net return was

Rs14677.32/ha and it ranged from Rs 13886.6 to Rs21019.6/ha depending upon

methods of weed control. The higher net return (Rs21019.6/ha) was obtained with

treatment T2-Use of Cono-weeder followed by T6-Ambika paddy weeder, T8-Closer

row spacing treatments. Mechanical weeding through cono-weeder at 25 and 45 DAT

resulted less weed infestation in the rice field throughout the crop growth which gave

favourable condition for rice growth and finally produced higher grain and straw

yields, consequently resulted in more profit. All the weed control treatments tried in


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this experiment were more profitable than the unweeded check plot. Similar results

were also reported by Ahmed et al.,(2008).

4.5.4 Benefit cost ratio

Benefit cost ratio(BCR) is the ratio of gross return to cost of cultivation which can

also be expressed as returns per rupee invested. The minimum benefit: cost ratio was

obtained under the control condition. This was due to the lowest grain yield obtained

in control condition (T1).


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SUMMARY AND CONCLUSION

A field experiment entitled Studies on the effect of weed management

options on the growth, yield and economics of scented Rice (Oryza sativa L.)

was conducted at the Instructional Farm, Indira Gandhi Krishi Vishwavidyalaya,

Raipur during the rainy season of 2011. The experiment was laid out in

randomized complete block design with three replications, having 8 treatments

(T1-weedy check, T2-Cono-weeder, T3-One hand weeding, T4-Two hand

weeding, T5-20 % Acetic acid, T6- Ambika paddy weeder T7- Burn oil spray

+ One H.W and T8- Closer row spacing) The soil of the experimental site was

clay loam in texture, having 22.10 % sand, 23.20 % silt and 53.12 % clay,

respectively, with pH of 7.18 The soil was low in organic carbon content (0.66 %),

low in nitrogen (218.5), medium in available phosphorus (17) and high in

available potassium (335 kg/ha). The results of the experiment are summed up as

follows:

As compared to weedy check, plant height at various growth stages increased up to

harvest stage. Use of cono weeder for weed control brought significantly greater

growth in terms of plant height

1. Number of tillers and effective tillers m-2 were maximum under the T2-Use of

Cono-weeder .

2. Plant height increased with the advancement of crop age. The maximum increase

was recorded under the treatment T6-Ambika paddy weeder followed by T2-Use

of Cono-weeder.


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3. The highest dry matter accumulation was observed in T2-Use of Cono-weeder

followed by T6-Ambika paddy weeder.

4. Panicle length was found the highest in T2-Use of Cono-weeder followed by T6-

Ambika paddy weeder .

5. Crop growth rate was found to be the maximum during 40-80DAT, thereafter it

deceased (during 80 DAT- at harvest).

6. The maximum test weight was observed with T2-Use of Cono-weeder followed by

followed by T4-Two H.W.

7. Weed control efficiency was maximum under T2-Use of Cono-weeder followed

by T6-Ambika paddy weeder followed by T4-Two H.W. and T3- One H.W.

8. The maximum grain and straw yield were observed under T2-Use of Cono-weeder

followed T6-Ambika paddy weeder followed by T4-Two H.W.

9. The maximum harvest index was recorded under T6-Ambika paddy weeder

followed by T2-Use of Cono-weeder followed by T4-Two H.W..

10. In the experimental field Comelina bengalensis, Echinochloa colona,

Alternanthera triandra, and cynotis axilaris were the dominant weed species in all

the stages of rice.

11. The infestation of weed species increased with the time in unweeded control

treatment. The weed density and dry matter of weeds deceased due to use of

different weed management practices. The lowest weed density and weed dry

matter at 40, 80 DAT and At harvest observed under the T2-Use of Cono-weeder

treatment and T6-Ambika paddy weeder and T4-Two H.W.


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12. The highest net return (Rs. 21019.58ha-1) benefit: cost ratio (0.80) and gross

return (Rs. 46992.8ha-1) was noted the T2-Use of Cono-weeder treatment followed

by T6-Ambika paddy weeder. The lowest net return (Rs. 13886.6 ha-1) benefit:

cost ratio (0.63) and gross return (Rs.35745.9) were noted under unweeded

control (T1).

Conclusion

On the basis of result obtained, it can be inferred that T2-Use of Cono-weeder

treatment twice at 25 and 45 DAT found prominent effect on growth characters of rice

like plant height, dry matter and number of effective tillers etc.

Among yield and yield attributing characters, like number of total tillers,

effective tillers, number of grains panicle-1, test weight, grain and straw yield were

maximum with T2-Use of Cono-weeder treatment twice at 25 and 45 DAT

T2-Use of Cono-weeder treatment twice at 25 and 45 DAT prominent effect

than any others in term of weed density, dry matter of weeds , weed control

efficiency.Also its application proved best with respect to rice production (maximum

rice yield 35.68q ha-1). The maximum total cost of cultivation (Rs37071.22 ha-1) was

recorded under T7-Burn oil spray + One H.W.. Maximum gross return Rs. 46992.8 ha-

1was obtained T2-Use of Cono-weeder followed by T6-Ambika paddy weeder

Suggestions for further research work

1. This experiment should be carried out for few more seasons to draw concrete

conclusion for the recommendation to rice growers.


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2. Large scale testing and need to be studied under different agro- ecological

situation.

3. Effect of different weed management practice of rice can also be tried for early

and medium duration rice variety.


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Appendix-I : Weekly meteorological data during crop growth period (from 25 June, 2011 to November 18, 2011)

Week

No

Month Date Temp (oC) Rainfall

(mm)

Relative

humidity

(%)

Vapour

pressure

Wind

velocity

(Kmph)

Evaporation

(mm)

Sun

shine

(Hrs)

Max Min I II I II26 June 25-01 30.6 20.9 11.3 88 69 21.8 21.5 11 3.8 2

Average 30.6 20.9 11.3* 88 69 21.8 21.5 11 3.8 2

27

July

02-08 33.4 25.1 23.4 86 67 22 21.8 5.1 4.5 4.8

28 09-15 32.6 25.5 58 90 67 23.2 23.3 6 4.7 5.3

29 16-22 29.7 24.1 206 94 82 22.3 22.6 10.5 3.9 1.8

30 23-29 30.7 25.1 50.8 88 66 22.9 22.2 4.1 4.4 4.5

31 30-05 32.2 25.8 75 92 77 23.9 25 3.8 4.2 5.4

Average 31.72 25.12 413.2* 90 71.8 22.86 22.98 5.9 4.34 4.36

32

Aug

06-12 28.9 24.7 92.4 95 82 22.9 23.6 5.1 3 0.6

33 13-19 30.1 24.6 76.9 94 76 23 23.1 3.9 4.2 3.3

34 20-26 30.8 24.4 59.6 92 75 23.2 23.5 2.5 3.5 5

35 27-02 29.4 24.6 150.1 96 82 23.3 24.3 3.4 3 2.5Average 29.8 24.575 379* 94.25 78.75 23.1 23.625 3.725 3.425 2.85

36

Sep

03-09 28.3 24.4 226 95 90 22.6 23.6 7.4 3.2 1.6

37 10-16 30.1 2.4 67 95 80 23.1 24.2 4.2 2.8 2

38 17-23 31 24 69.2 94 74 22.7 22.3 2.9 3.8 5.2

39 24-30 31.2 22.8 2.4 89 52 21.5 17.6 4.6 4 5.8

Average 30.15 18.4 364.6* 93.25 74 22.475 21.925 4.775 3.45 3.65

40

Oct

01-07 32.4 21.8 0 90 43 19.6 15.5 2.2 4.4 8.8

41 08-14 32.4 24 24.8 92 57 21.8 19.7 1.7 3.9 7.2

42 15-21 32.6 20.8 0.8 90 37 17.8 13.2 1.7 4.3 9.1

43 22-28 31.8 17.7 0 92 35 15.5 11.8 1.3 4.4 4.7

44 29-04 30.8 15.2 0 91 27 13.5 8.5 1.4 4.2 9

Average 32 19.9 25.6* 91 39.8 17.64 13.74 1.66 4.24 7.7645

Nov

05-11 33.2 15.8 0 90 28 13.3 9 0.8 4 8.1

46 12-18 31.2 15.7 0 88 30 12.5 9.7 0.9 3.9 8

Average 32.2 15.75 0* 89 29 12.9 9.35 0.85 3.95 8.05

1193.7**


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Appendix II : Fixed cost of cultivation of rice ha-1

S.

No.

Particulars Rice

Input Rate (Rs.) Total cost

(Rs ha-1)

A

.

Nursery

a. Land Preparation

(Ploughing, harrowing

and levelling)

1 Tractor (1 hrs) 400 400.00

b. Seed bed Preparation 4 Man days 157.64 630.56

c. FYM 500 kg 0.7 Rs kg-1 350.00

d. Seed treatment

PSB 600g. 1000 Rs kg-1

600

Azospirillum (AZO) 200g 1000 Rs kg-1

200

B. Transplanting

a. Ploughing (once) 1 Tractor (3 hrs) 400 1200.00

b. Puddling and leveling(once)

1 Tractor (3 hrs) 400 1200.00

c. Transplanting 15 man days 157.64 2364.60

d. Irrigation 4 irrigation,+ 2

man days

450+157.64 2115.28

e.Organic manureCow dung manure (CDM) 1307 700 ton-1 915

Compost crop residue (CCR) 1700 700 ton-1 1190

vermicompost (VC) 1041 2000 ton-1 2082

BGA 10 kg 10 kg-1 100

Rock phosphate (RP) 100kg 750 q-1 750

f. Harvesting 15 man days 157.64 2364.60

g.Threshing and winnowing 15 Man days 157.64 2364.60

C. Land revenue - 500.00 500.00A. Common cost 19326.64

B. Miscellaneous 10% of common cost 1932.664

Grand Total (A+B) 21259.3


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Appendix III : Cost of different weed management treatments

Treatment Quantity

(lit. ha-1)

Rate

(Rslit-1)

No of

labourforspraying( ha-1)

Cost of

spraying(Rs.ha-1)

No of

labourforWeeding

Weeding

(Rs. ha-1)

Seed

Kg ha-1

Rate

Rs.kg-1

Total cost

(Rs. ha-1)

T1-Weedy

Check

- - - - 40 15 600

T2-Use of

Cono-

weeder

- - - 14+14 4413.9

2

20 15 4713.92

T3- One

H.W.

- - - 20 3152.8 40 15 3752.8

T4-Two

H.W.

- - - 20+20 6305.6 40 15 6905.6

T5-20 %

Acetic acid

240 45 2+2 630.56 - 40 15 11715.28

T6-Ambika

paddy

weeder

- - - 10+10 3152.8 40 15 3752.8

T7-Burn oil

spray +One H.W.

476.19 24 2+2 630.56 20 3152.8 40 15 15811.92

T8-Closer

row spacing

- - - - 53.33 15 799.95

iv result & dis pravir

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