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Effect of cocoon parameters of silkworm as influenced by different spacing in Mulberry, Morus alba. L.

In India, the major silk producing traditional states are Karnataka, Andhra Pradesh, Tamil Nadu, West Bengal and Jammu and Kashmir. In Karnataka, the major districts producing silk are Chikkaballapur (1253.99 MT), Kolar (1499.03 MT), Ramanagara (1665.98 MT) and Mandya (1597.09 MT) (Anonymous, 2012 b). In these districts, the cocoon crop vary according to, method of mulberry cultivation, package of practices adopted in both rainfed and irrigated condition and silkworm rearing house. Thus, quality of mulberry leaf plays a major role in successful cocoon production. Further, the quality of mulberry leaf depends on the variety of mulberry, soil type, methods of cultivation and the inputs used.

In this context, it was thought necessary to investigate the suitable planting system, which can maximize the leaf yield, quality of mulberry on cocoon yield.

MATERIALS AND METHODS

Investigations were carried out to know the "The evaluation of rearing performance of silkworm as influenced by different spacing in mulberry morus alba. 1.". The experiments were conducted in University of Agricultural Sciences, Bengaluru, College of Sericulture, Chintamani during the year 2013-14.

Silkworm rearing Disinfection of rearing room

Before commencement of rearing the silkworm rearing room and equipments were washed with water, then disinfected using 0.2 % Decol solution at the rate of 2 litres per [m.sup.2] plinth area.

Choice of silkworm breed

The commercial cross breed PM x [CSR.sub.2] was used for the study. The disease free layings (DFLs) were procured from NSSO grainage, CSB, Chintamani.

Incubation of dfls

Five DFLs were kept on paraffin paper in plastic trays and covered with another paraffin paper. The optimum temperature and relative humidity was maintained by keeping moist foam rubber strips all around the egg sheets. The eggs were subjected to black boxing for 24hrs at blue egg stage. After which the eggs were exposed to diffused light on the expected day of hatching to obtain uniform hatching.

Brushing

The newly hatched larvae were provided with chopped mulberry leaves of required quantity and quality. After 30 minutes of feeding, the larvae were transferred on to the plastic trays along with the mulberry leaves having paraffin paper at the bottom and wet foam rubber strips provided all round.

Silkworm rearing

Mass rearing was done in plastic tray from brushing till third moult. The worms were reared by feeding three times a day (8.30 A.M., 12.30 P.M. and 6.30 P.M). Bed cleaning was done once twice and thrice during I, II, III instars, respectively. Whereas, daily once during IV and V instar. During rearing, optimum spacing was provided according to the age of silkworm, after each bed cleaning. Lime powder was dusted on silkworm before settling for moult so as to keep the bed dry and facilitate easy moulting in each moult a bed disinfection with Vijetha was practiced. The rearing trays were covered with uzi fly proof nylon nets. After III instar, hundred worms were allocated for each replication.

Feeding

The mulberry leaves were harvested during cooler hours of the day from mulberry plots with different spacings. The leaves of respective spacing were fed to worms separately. Leaves were provided to chawki worms whereas whole shoot feeding was followed for late age silkworm rearing. Mounting and harvesting

The ripe worms were handpicked and mounted on bamboo mountage as per treatment and cocoons were harvested manually on 4th day of mounting.

Observation recorded Cocoon weight (g)

Ten cocoons were randomly picked from each replication of every treatment and weight was recorded on the fifth day of mounting and average weight was calculated.

Cocoon yield (kg)

Cocoon yield per 100 worms reared in each replication was calculated to get cocoon yield. Shell weight (g)

After taking cocoon weight cocoons were cut open and ten empty shells were weighed for each replication and treatment.

Silk filament length (m)

Five cocoons per replication were selected and each cocoon was reeled using eupprovette and silk filament length was recorded. Filament length was calculated by the formula,

L= R x 1.125m

Where, in

L = Length of the silk filament (m).

R = Number of revolutions.

1.125m = Circumference of the euprovette.

Silk filament weight (g)

The reeled silk filament from each cocoon was dried, by keeping in hot air oven at 80[degrees]C and weight was recorded using electronic balance.

Shell ratio (%)

Shell ratio was calculated by using the formula

Shell ratio = [Shell weight (g)/Whole cocoon weight (g)] x 100

Denier

Denier was found out by using the formula,

Denier = [Weight of silk filament (g)/Length of silk filament (m)] x 9000

RESULTS AND DISCUSSION

Rearing parameters Commercial characters of cocoons

Maximum cocoon weight and cocoon yield was recorded in 9x3 ft spacing (19.84 g/ten cocoon and 0.69 kg cocoon yield/400 worms in first rearing and 17.72 g/ten cocoon and 0.41 kg cocoon yield/400 worms in second rearing. However significantly lowest was recorded in 3x3 ft spacing [16.23 g/ten cocoon and 0.48 kg cocoon yield/400 worms in first rearing 13.43 g/ten cocoon and 0.41 kg cocoon yield/400 worms in second rearing. The increase in cocoon weight is mainly due to increase in the larval weight and better nutrition. The cocoon yield was recorded highest in first rearing compare to second rearing this is mainly due to disease incidence in second rearing, while there was no disease incidence in first rearing. These findings are in accordance with Rahman et al. (1999).

Shell weight also differed significantly between the treatments wherein maximum shell weight was recorded in 9x3 ft spacing (3.72 g/10 shells in first rearing and 3.14g/10 shells in second rearing). However, lowest shell weight was recorded in 3x3 ft spacing (2.70 g/10 shells in first rearing and 2.11 g/10 shells in second rearing). These results differed from findings of Rao et al, (2000).

Silk filament length and weight was found to be highest in 9x3 ft spacing (790.52 m and 0.25 g respectively in first rearing and 751.34 m and 0.21 g respectively in second rearing), and least was recorded in 3x3 ft spacing (670.45 m and 0.15 g respectively in first rearing and 630.34 m, 0.21 g respectively in second rearing). Increased filament length might be attributed to increased shell weight and increase in filament weight increases to increased filament length. These results are in conformity with that of Ghosh et al. (2009) who observed that cocoon yield/100dfls, Shell per cent, Filament length(m) and Reelability (%) were significantly superior in paired row plantation [(150+90)x60 cm].

Shell ratio differed significantly between treatments and maximum shell ratio was recorded in 9x3 ft spacing (18.72 per cent in first rearing and 16.17 per cent in second rearing). However, minimum shell ratio was recorded in 3x3 ft spacing (15.02 % in first rearing and 13.43 per cent in second rearing). Similar results are also observed by Ramakanth et al. (2001)

However, denier was found to be highest in 9x3 ft spacing (2.87 in first rearing and 2.53 in second rearing) and lowest was recorded in 3x3 ft spacing (2.01 in first rearing and 1.96 in second rearing). This might have resulted because of the better environment, nutrition and contributory factors expressed in rearing.

REFERENCES

(1.) Anonymous, Annual Administration Report, Department of Sericulture, GOK, Bengaluru, 2012; 37.

(2.) Rahman, M. S., Doss, S. G., Vijayan, K. and Roy, B.N., Performance of the mulberry variety S-1635 under three system of planting in west Bengal. Indian J. Seric., 1999; 38(2): 165-167.

(3.) Rao, P. A., Mallikarjunappa, R.S. and Dandin, S. B., Studies on effect of different plant spacing on leaf yield and quality of M-5 mulberry genotype under semi-arid conditions of Karnataka. Karnataka J. Agril.Sci., 2000; 13(4): 882-886.

(4.) Ghosh, A., Dutta, T., Saha, A. K., Shivnath., Kar, N. B., Mandal, K. and Bajpai, A. K., Effect of planting geometry on leaf yield and quality of mulberry chawki garden. J. Crop and Weed, 2009; 5(1): 44-47.

N.C. Ananya [1], Gururaj [1], H.C. Swathi [1] and M. Vijayendra [2]

[1] Department of Sericulture, UAS, GKVK, Bengaluru - 560 065, India..

[2] College of Agriculture, Chintamani, Chikkaballapur district, India.

(Received: 08 December 2015; accepted: 22 January 2016)

* To whom all correspondence should be addressed. E-mail: swathicng@gmail.com
Table 1. Impact of different spacings in mulberry on cocoon
parameters of silkworms (first rearing-October 2013)

Treatments                  Weight of     Cocoon       Weight of
                            ten           yield        10 cocoon
                            cocoons       (kg/400w     shell (g)
                            (g)           orms)

T1-9x3 ft. spacing          19.84a        0.69 a       3.72 a
T2-6x3 ft. spacing          17.23         0.58         3.01
T3-(6+3) x 3 ft. spacing    18.53b        0.64 b       3.29 b
T4-3x3 ft. spacing          16.23         0.48         2.70
T5-(5+3) x 2 ft. spacing    18.12b        0.61         3.19
F- test                     *             *            *
SE.m [+ or -]               0.159         0.013        0.011
CD at 5%                    0.480         0.039        0.033

Treatments                  Single        Single       Shell     Denier
                            cocoon silk   cocoon       ratio
                            filament      filament     (%)
                            length (m)    weight (g)

T1-9x3 ft. spacing          790.52 a      0.25 a       18.72 a   2.87 a
T2-6x3 ft. spacing          700.57        0.17         17.48     2.21
T3-(6+3) x 3 ft. spacing    763.13 b      0.23 b       17.75 b   2.74 b
T4-3x3 ft. spacing          670.45        0.15         16.64     2.01
T5-(5+3) x 2 ft. spacing    723.32        0.21         17.61     2.61
F- test                     *             *            *         *
SE.m [+ or -]               1.465         0.006        0.056     0.067
CD at 5%                    4.416         0.017        0.169     0.203

Table 2. Impact of different spacings in mulberry
on cocoon parameters of silkworms
(second rearing-April 2014)

Treatments                  Weight of    Cocoon
                            ten          yield
                            cocoons      (kg/400w
                            (g)          orms)

T1-9x3 ft. spacing          17.72 a      0.65 a
T2-6x3 ft. spacing          15.86        0.53
T3-(6+3) x 3 ft. spacing    15.17        0.55
T4-3x3 ft. spacing          13.43        0.41
T5-(5+3) x 2 ft. spacing    16.93 b      0.59 b
F. test                     *            *
SE.m [+ or -]               0.040        0.021
CD at 5%                    0.122        0.062

Treatments                  Weight of    Single
                            10 cocoon    cocoon silk
                            shell (g)    filament
                                         length (m)

T1-9x3 ft. spacing          3.14 a       751.34 a
T2-6x3 ft. spacing          2.83         692.42
T3-(6+3) x 3 ft. spacing    2.93         698.12
T4-3x3 ft. spacing          2.11         630.34
T5-(5+3) x 2 ft. spacing    3.07 b       713.53 b
F. test                     *            *
SE.m [+ or -]               0.016        1.246
CD at 5%                    0.048        3.754

Treatments                  Single       Shell         Denier
                            cocoon       ratio
                            filament     (%)
                            weight (g)

T1-9x3 ft. spacing          0.21 a       16.17 a       2.53 a
T2-6x3 ft. spacing          0.15         15.02         2.14
T3-(6+3) x 3 ft. spacing    0.16b        15.13         2.43
T4-3x3 ft. spacing          0.12         13.43         1.96
T5-(5+3) x 2 ft. spacing    0.18 b       15.79 b       2.49 b
F. test                     *            *             *
SE.m [+ or -]               0.015        0.037         0.019
CD at 5%                    0.047        0.111         0.058
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Author:Ananya, N.C.; Gururaj; Swathi, H.C.; Vijayendra, M.
Publication:Journal of Pure and Applied Microbiology
Article Type:Report
Date:Mar 1, 2016
Words:1884
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