Strategies for Enhancement in Food Production

Plant breeding, Disease control,Hybridisation


  • Plant breeding is the purposeful manipulation of different plant species inorder to create desired plant types that are better suired for cultivation, better yield and disease resistance.
  • Main steps in plant breeding:
    (i) Collection of Variability (germplasm collection)
    (ii) Evaluation and selection of parents
    (iii) Common methods of crop improvement
    (iv) Selection & testing of superior recombinants.
    (v)Testing, release. and commercialization of new varieties
  • Plant Breeding for disease resistance.
    crop losses are upto 20-30% due to fungal, bacterial viral and nematode pathogens attack. on the cultivated crops.
  • Breeding is carried out by the conventional breeding techniques or by mutation breeding. The conventional method of breeding for disease resistance is that of hybridisation and selection.
  • Mutational breeding is possible to induce mutations artificially through use of chemicals / radiations (γ rays) and selecting, using the plants that have desirable characters as a source in breeding.
  • Sharbati sonora and Pusa Lerma are two important varieties of wheat produced by gamma rays treatment of sonora - 64 Lerma - 64 (mexican dwarf wheat varieties). In mung bean, resistance to YMY and powdery mildew were induced by mutation.
  • Hybridization and selection are used for breeding some crop varieties.

CROP

Variety

Resistance to diseases

Wheat

Himgiri

Leat and stripe rust, hill bunt

Brassica

Pusa swarnim

White rust

Cauliflower

Pusa shubhra, Pusa snowball K1

Black rot and curl blight black rot

Cowpea

Pusa komal

Bacterial blight

Chilli

Pusa sadabahar

Chilly Mosaic vines, Tobacco Mosaic virus, and leaf curt.

Bhindi

Prabhani Kranti

Yellow mosaic virus

  •  Breeding for resistance to insect pests

Crop

Variety

Resistance to disease

Brassica (Rapeseed mustard)

Pusa Gaurav

Aphids

Flat been

Pusa sem 2  Pusa sem 3

Jassids, aphids & fruit borer

Okra (Bhindi)

Pusa Sawani Pusa A - 4

Shoot and fruit border.

 

  • Tissue culture - plant tissue culture is a technique of growing cells, tissue, organ or organism in sterilised nutrient media under controlled aseptic conditions.
  • The concept of totipotency (Capacity to generate the whole plant from any part of plant) was given by Haberlandt who is considered as father of plant tissue culture.
  • Practical application of totipotency was shown by steward who developed a complete carrot from a single cell obtained from root of new plant.
  • Tissue culture medium can be liquid or solid. It contains source of carbon (sucrose is main 'c' source), minerals, glycine, vitamins, growth regulators (Hormones such as auxin like 2, 4 - D, cyrokinin like BAP, Gibberlins (GA) ABA, polyamine (putrescine))
  • Micropropogation is the ability to generate thousands of plants through tissue culture technique. The identical plants generated by tissue culture technique is called as somalones.
  • Plant part used for tissue culture is called explant. The explant and medium should be sterilized (surface sterilization → explant, dry heat & stem used for glassware & media)
  • Depending upon type of explant, tissue culture is called shoot tip culture, multiple shoot culture anther / haploid culture, embryo culture etc.
  • On the basis of in vitro growth, plant tissue cultures are two types namely callus and suspension culture
  • In callus culture, cell division in explant forms a callus. callus is irregular, undifferentiated and actively dividing mass of cells is often produced or agar medium.
  • In suspension culture, a single cell / small group of cells are suspended in liquid medium containing auxin (2-4D) and is constantly agitated at the speed of 100 - 250 rpm.
  • Embryo culture involves excision of young embryo from seeds and their growth on culture medium to form seedings and then young plants.
  • Application of embryo culture (a) seeds lack stored nutrients required for seeding growth can be growth using this eg: orchid (b) Used in multiplication of some rare plants lice macapuno coconuts.
  • Haploid culture / Androgenic haploid / pollen grain culture was developed by Guha & Maheshwari (1964) in Datura innoxia.
  • Young unopened floral buds are first sterilized in clorox for 20 - 40 minutes. Thees they are opened to remove anther which are introduced over culture medium. Within 4 - 6 weeks, each anther giver rise to a number of haploid embryoids. Colchicine treatment result in doubling of chromosome and produce homozygous diploids, for each and every fruit.
  • Winter wheat yinghua - 1 and rice Guan - 18 are two important varieties which are produced by haploid culture technique.
  • Meristem is localized group of cells which are actively dividing and undifferentiated, giving rise to permanent tissue. Although plant is infected with virus, the meristem (apical / axillary) is free of virus so, meristem can be grown in vitro to obtain virus - free plants.
  • The explants commonly used in meristem culture are shoot tips and nodal segments, which are generally cultured on a medium containing cytokinin (BAP). This culture is carried out in potano, Banana, Cardamon, Orchids, sugarcane, strawberry, sweet potato etc.
  • Protoplast culture :-
    The plant cells are first treated with pectinase and cellulose which dissolve the cell wall as a result naked protoplast is produced.
  • Protoplasmic fusion / somatic hybridisation :-
    The two protoplast (eg for somatic cell) are fused by
    (i) ecectro fusion (high voltage pulse)
    (ii) chemo - fusion (chemicals) PEG / Sodium nitrate)
  • The somatic hybrid may have synkaryon (single fused nucleus) or heterokaryon (two unfused nucleus) the hybrid protoplast is called cytoplasmic hybrid or cybrid if one of the two nuclei of this get degenerated.
  • Pomato is somatic hybrid between potato and tomato (2 difference gevera), Bomato (Brinjal and tomato). The first somatic hybridisation was done between Nicotiana glauca & N. langsdorf (species of to bacco) by Carlson et. al (1972). 

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