SERICULTURE SILK

WHAT IS SILK –

  • MAN IS ALWAYS INQUISITIVE FOR SILK PRODUCTS. SILK – THE QUEEN OF TEXTILES, SPELLS LUXURY, ELEGANCE, CLASS AND COMFORT. MANKIND HAS ALWAYS LOVED THIS SHIMMERING FIBRE OF UNPARALLELED GRANDEUR FROM THE MOMENT CHINESE EMPRESS SHILING TI DISCOVERED IT IN HER TEA CUP. IT WITHSTOOD MANY A DAUNTING CHALLENGES FROM OTHER NATURAL AND ARTIFICIAL FIBRES AND YET, REMAINED THE UNDISPUTED QUEEN OF TEXTILES SINCE CENTURIES. EXQUISITE QUALITIES LIKE THE NATURAL SHEEN, INHERENT AFFINITY FOR DYES AND VIBRANT COLOURS, HIGH ABSORBANCE, LIGHT WEIGHT, RESILIENCE AND EXCELLENT DRAPE ETC. HAVE MADE SILK, THE IRRESISTIBLE AND INEVITABLE COMPANION OF THE EVE, ALL OVER THE WORLD.
  • CHEMICALLY SPEAKING, SILK IS MADE OF PROTEINS SECRETED IN THE FLUID STATE BY A CATERPILLAR, POPULARLY KNOWN AS ‘SILKWORM’. THESE SILKWORMS FEED ON THE SELECTED FOOD PLANTS AND SPIN COCOONS AS A ‘PROTECTIVE SHELL’ TO PERPETUATE THE LIFE. SILKWORM HAS FOUR STAGES IN ITS LIFE CYCLE VIZ., EGG, CATERPILLAR, PUPA AND MOTH. MAN INTERFERES THIS LIFE CYCLE AT THE COCOON STAGE TO OBTAIN THE SILK, A CONTINUOUS FILAMENT OF COMMERCIAL IMPORTANCE, USED IN WEAVING OF THE DREAM FABRIC.

WHERE DO WE FIND SILK

  • GEOGRAPHICALLY, ASIA IS THE MAIN PRODUCER OF SILK IN THE WORLD AND PRODUCES OVER 95 % OF THE TOTAL GLOBAL OUTPUT. THOUGH THERE ARE OVER 40 COUNTRIES ON THE WORLD  MAP OF SILK, BULK OF IT IS PRODUCED IN CHINA AND INDIA, FOLLOWED BY JAPAN, BRAZIL AND KOREA. CHINA IS THE LEADING SUPPLIER OF SILK TO THE WORLD.
  • INDIA IS THE SECOND LARGEST PRODUCER OF SILK AND ALSO THE LARGEST CONSUMER OF SILK IN THE WORLD. IT HAS A STRONG TRADITION AND CULTURE BOUND DOMESTIC MARKET OF SILK. IN INDIA, MULBERRY SILK IS PRODUCED MAINLY IN THE STATES OF KARNATAKA, ANDHRA PRADESH, TAMIL NADU, JAMMU & KASHMIR AND WEST BENGAL, WHILE THE NON-MULBERRY SILKS ARE PRODUCED IN JHARKHAND, CHATTISGARH, ORISSA AND NORTH-EASTERN STATES.
  • SILKWORM LARVAE ARE FED MULBERRY LEAVES, AND, AFTER THE FOURTH MOULT, CLIMB A TWIG PLACED NEAR THEM AND SPIN THEIR SILKEN COCOONS. THE SILK IS A CONTINUOUS-FILAMENT FIBER CONSISTING OF FIBROINPROTEIN, SECRETED FROM TWO SALIVARY GLANDS IN THE HEAD OF EACH LARVA, AND A GUM CALLED SERICIN, WHICH CEMENTS THE TWO FILAMENTS TOGETHER.
  • THE SERICIN IS REMOVED BY PLACING THE COCOONS IN HOT WATER, WHICH FREES THE SILK FILAMENTS AND READIES THEM FOR REELING. THE IMMERSION IN HOT WATER ALSO KILLS THE SILKWORM PUPAE.
  • SINGLE FILAMENTS ARE COMBINED TO FORM THREAD. THIS THREAD IS DRAWN UNDER TENSION THROUGH SEVERAL GUIDES AND WOUND ONTO REELS. THE THREADS MAY BE PLIED TOGETHER TO FORM YARN. AFTER DRYING THE RAW SILK IS PACKED ACCORDING TO QUALITY

TYPES OF SILK

  • THERE ARE FOUR MAJOR TYPES OF SILK OF COMMERCIAL IMPORTANCE, OBTAINED FROM DIFFERENT SPECIES OF SILKWORMS WHICH IN TURN FEED ON A NUMBER OF FOOD PLANTS. THESE ARE:
    • CLASSIFICATION BASED ON SPECIES. ALL ARE DIFFERENT SPECIES
      •  MULBERRY
      • OAK TASAR & TROPICAL TASAR
      • MUGA
      • ERI
    • CLASSIFICATION BASED ON OCCURRENCE .
      • DOMESTICATED – MULBERRY, REARED TASAR
      •  WILD- TASAR MUGA AND ERI. WILD SILKS ARE ALSO CALLED VANYA SILK
    • CLASSIFICATION BASED ON ECORACES
      • MULBERRY – VARIOUS GEOGRAPHIC VARIETIES.
      • TASAR- NATURAL , REARED,
    • CLASSIFICATION BASED ON LIFE CYCLES PER YEAR.
      • . MULTI VOLTINE – MORE THAN 2 LIFECYCLES PER YEAR. MULBERRY AND TASAR IN CENTRAL AND SOUTH INDIA.
      •  BI VOLTINE – TWO LIFE CYCLES PER YEAR. TASAR IN TROPICAL AREAS. MULBERRY IN TROPICAL AREAS AS AN IMPROVED VARIETY.
      • UNI VOLTINE- ONE LIFE CYCLES PER YEAR. OAK TASAR AND MULBERRY IN TEMPERATE AREAS. KASHMIR, HIMACHAL AND CHINA

SILK PRODUCTION IN THE WORLD AND INDIA

  • STAGES OF PRODUCTION
    • THOUGH ALL FOUR TYPES OF SILKWORMS HAVE DIFFERENT FOOD PLANTS AND AGRO-CLIMATIC
      ZONE BUT THE BASIC LIFE CYCLE IS ALMOST THE SAME.
    • THE STAGES OF PRODUCTION ARE AS FOLLOWS:
      • THE SILK MOTH LAYS EGGS.
      • WHEN THE EGGS HATCH, THE CATERPILLARS ARE FED FOOD PLANTS LEAVES.
      • WHEN THE SILKWORMS ARE ABOUT 25 DAYS OLD, THEY ARE 10,000 TIMES HEAVIER THAN WHEN THEY HATCHED. DURING THE FEEDING PERIOD THE SILK WORM GOES 4 TO FIVE TIMES IN MOLT WHICH IS ITS PROPERTY TO SHED ITS SKIN AS IT GROWS ALARMINGLY FAST IN SIZE.
      • THEY ARE NOW READY TO SPIN A SILK COCOON.
      • THE SILK IS PRODUCED IN TWO GLANDS IN THE SILKWORM’S HEAD AND THEN FORCED OUT IN LIQUID FORM THROUGH OPENINGS CALLED SPINNERETS.
      • THE SILK SOLIDIFIES WHEN IT COMES IN CONTACT WITH THE AIR.
      • THE SILKWORM SPINS APPROXIMATELY 0.8 KM TO 1.5 KM OF FILAMENT AND COMPLETELY ENCLOSES ITSELF IN A COCOON IN ABOUT TWO OR THREE DAYS .THE SILK IS OBTAINED FROM THE UNDAMAGED COCOONS BY BOILING THE COCOON TO FIND THE OUTSIDE END OF THE FILAMENT.
      • THE LIVE PUPA INSIDE THE COCOON DIES DUE TO BOILING.
      • THE SILK FILAMENTS ARE THEN WOUND ON A REEL. THE SILK AT THIS STAGE IS KNOWN AS RAW SILK.
      • IN ORDER TO CONTINUE THE LIFE CYCLE NOT ALL COCOONS ARE BOILED AND REELED. SOME GOOD COCOONS ARE PRESERVED AND THE MOTH IS ALLOWED TO COME OUT AND LAY EEGS SO THAT THE
        LIFE CYCLES IS CONTINUED FOR THE NEXT CROP ARE SEASON.