Plant Ideotype Concept

Plant Ideotype

PLANT IDEOTYPE CONCEPT

INTRODUCTION

  • It’s a biological model that’s supposed to function or react in a certain way in a certain environment.
  • C.M. Donald coined the word “ideotype” (1968)
  • According to Donald, a crop ideotype is a plant modal that, when developed as a cultivar, is predicted to generate a higher amount or quality of grain, oil, or other valuable commodity.

Main Points about Ideotype

  • A model plant or ideal plant type for a certain climate is referred to as a crop ideotype.
  • To identify a wheat ideotype, Donald used just morphological parameters; later, physiological and biochemical variables were included to widen the idea of crop ideotype.
  • Old varieties are predicted to yield less than ideal plants.
  • Ideotype is a fluid concept that shifts with the seasons, type of agriculture, market demand, and so on.

SYNONYMS OF IDEOTYPE

  • Type of model plant
  • Type of model plant
  • Plants that are ideal

FEATURES OF PLANT IDEOTYPE

  • The most effective use of natural resources will be an Ideotype.
  • Each unit of dry matter generated will have a sufficient number of flowers/florets or other sinks to receive all photosynthates from the plant’s green surface or from other portions.
  • Ideotype is a fluid concept.
  • The physical and physiological qualities of the Ideotype must result in a high harvest index.
  • Ideotype crops must be grown as far as feasible in weed-free environments.

TYPE OF PLANT IDEOTYPE (DONALDS)

Market Ideotype:

The qualities decide whether or not the produce is marketable. (Seed colour, seed size, preparation, and backing)

Climatic Ideotype

Important characteristics for climate adaptation: (Early maturity, thermoperiod insensitivity, Heat and Cold tolerance, drought tolerance)

Edaphic Ideotype:

Salinity tolerance, mineral toxicity, and deficient tolerance traits

Stress Ideotype:

Resistance to biotic and abiotic stress was one of the traits studied.

Disease or pest Ideotype

Resistance to the illness and pests in question is influenced by traits.

Insect Ideotype

Resistance to the insects in question is based on traits.

WHAT IS IDEOTYPE BREEDING

IDEOTYPE BREEDING:- 

Ideotype breeding, also known as plant type breeding, is a method of crop improvement that involves genetic modification of individual plant characters to increase genetic yield potential.

WHY WE SELECT THE IDEOTYPE BREEDING:

  • Individual plant characteristics are selected.
  • Various morphological, physiological, and biochemical plant traits are used in ideotype breeding.
  • Each trait’s worth is predetermined.
  • The phenotype of the new variety to be created is predetermined.

Differences between Traditional breeding & Ideotype breeding                                            

Traditional breeding Ideotype breeding
The main objective is defined before initiating the breeding work The conceptual theoretical model is prepared before initiation of breeding work.
Selection is focused on yield and some other characters. Selection is focused on individual plant characters
It usually includes various morphological and economic characters It includes various morphological, physiological and biochemical plant characters.
Value of each character is not fixed in advance. Value of each trait is defined in advance.
This is a simple and rapid method of cultivar development. This is a difficult and slow method of cultivar development.
The phenotype of a new variety is not specified in advance. Phenotype of new variety to be developed is specified in advance.

STEPS INVOLVED IN IDEOTYPE BREEDING

  • Development of conceptual theoretical model.
  • Selection of base material
  • Incorporation of desirable characters into a single genotype
  • Selection of ideal or model plant type

CHOICE OF TRAITS FOR IDEOTYPE/ SELECTION

  • The importance of trait in enhancing yield.
  • Heritable variation must be present for the character
  • The measurement of trait should be inexpensive and reliable.
  • The trait should have high  heritability

WHEAT IDEOTYPE (Donald, 1968)

    Characters:

  • Dwarf stature
  • Uniculm nature- short and strong
  • Awns present
  • Large ear and erect
  • Few, small and erect leaves
  • A short and strong stem
  • High proportion of seminal roots

MAIN FEATURES OF WHEAT IDEOTYPE

  1. Short strong stem:-

It reduces the risk of lodging and would also reduce the amount of photosynthates invested in stem production.

  1. Erect leaves:-

Such leaves provide better arrangement for proper light distribution resulting in high photosynthesis or CO2 fixation.

  1. Few small leaves:-

Leaves are the important sites of photosynthesis, respiration and transpiration. Few and small leaves. Reduce water loss due to transpiration.

  1. Larger ear:-

It will produce more grains per ear.

  1. An erect ear:-

It will get light from all sides resulting in proper grain development.

  1. Presence of awns:-

Awns contribute towards Photosynthesis.

MODERN WHEAT PLANT TYPE

CIMMYT breeders are defining a spectrum of optimum wheat plant ideotypes based on greater knowledge of the physiological grounds of yield.

Plants with enormous spikes and many grains per spikelet

The optimization of source-sink interactions is also being investigated in order to achieve a better balance of grain filling characteristics with cases of excessive expressiveness. The hexaploid wheat gene pool, as well as other gene pools, are being investigated.

Ideotype of Rice

  • Shorter culm length (100 cm)
  • Greater culm diameter which increases culm strength.
  • Lower relative internode elongation
  • High tillering capacity
  • Short, erect, thick and highly angled leaves
  • High harvest index
  • More penicles/ m2

NEW PLANT TYPE OF RICE (IRRI)

  • Low tillering,(9-10 tillers for transplanted conditions)-all of them productive
  • No unproductive tillers

Ideotype of Maize

  • 200-250 grains per penicle
  • Dark green, thick and erect leaves
  • Vigorous and deep root system
  1. Low tillers
  2. Large cobs
  3. Angled leaves for good light interception

Ideotype of Barley

  1. Long awns
  2. High harvest index
  3. High biomass
  4. Short stature

Ideotype of Cotton

  1. Short stature (90 – 120 cm )
  2. Short duration (150 -165 days )
  3. Responsive to high fertilizer dose
  4. High degree of resistance to insect, pest and  diseases.

IRRIGATED CONDITION:-

  • Plants of short stature (90 – 120 cm).
  • Responsive to high fertilizer dose.
  • High degree of resistance to insects, pests and diseases.
  • High physiological efficiency.
  • Short duration (150 – 165 days).

RAINFED CONDITION:-

  • Short stature (75- 80cm) and compact plant habit.
  • Responsive to nutrients.
  • High Degree of resistance to insects and diseases.
  • Medium to big boll size (3.5 – 4 gm ).

Practical achievements

  • Through the application of the dwarfing gene, ideatype breeding has considerably helped to increased yields in cereals (wheat, rice) and millets (sorghum, pearl millet), culminating in the green revolution.
  • Dwarfing gene sources include Norin 10 in wheat and Dee- geo-woo-gen in rice.
  • Wheat and rice semidwarf types are very responsive to water consumption and nitrogen application, and have a wide range of adaptability.
  1. Semidwarf rice varieties: IR-8, IR-20, TN-1
  2. Wheat semidwarf varieties: Kalyan sona, Sonalika

Factors affected to Ideotype breeding:-

  • Crop species
  • Cultivation
  • Socio – economic condition of farmers
  • Economic use
  1. Crop Species:-

 Ideotype differs from crop to crop

  • In monocots :- Tillering is important
  • In dicots: – branching is important.
  1. Cultivation:-

                The features of irrigated crops differ from that of rainfed crop.

  1. Socio- economic condition of farmers:-

                Dwarf sorghum is del for mechanical harvesting in USA but it is not suitable for the farmers of Africa where the stalks are used for fuel of hut construction.

  1. Economic use:-

The Ideotype also differs according to the economic use of the crop

  • Dwarf types are useful in sorghum and pearl millets when the crop is grown for grain purpose but when it is grown for fodder purpose taller stature is required. 
  • Less leafy type: – grain purpose
  • More leafy type: – fodder purpose

MERITS OF IDEOTYPE BREEDING

  • Ideotype breeding is a technique for increasing yield by manipulating several morphological and physiological crop characteristics.
    The values of many physical and physiological features are provided in this manner.
  • Plant breeding, physiology, biochemistry, entomology, and plant pathology professionals are all involved in ideotype breeding. Each expert helps to build model plants with features relevant to his or her specialty.
  • Ideotype breeding combines desirable genes for these qualities from several sources into a single genotype to solve problems such as disease, pest, and lodging resistance, maturity length, yield, and quality.
  • It’s a good way to create cultivars for a certain scenario or habitat.

LIMITATIONS

  • It is challenging to combine qualities from several sources into a single genotype.
  • Ideotype breeding is a time-consuming process.
  • Ideotype breeding is a costly process.
  • Traditional or conventional breeding cannot be replaced by ideatype breeding.
  • Ideotype breeding is a dynamic process.

FUTURE  PROSPECTS

  • Ideotypes for bad situations should be established.
  • Cropping development Ideotype is a never-ending process.
  • Various approaches can be used in the creation of new plant types.
  • Crop Ideotypes have been produced for cereals and millets, but they may now be developed for oil seeds, cotton, and pulses as well.
  • Hybrid Ideotype development has a lot of potential in crops including maize, sorghum, pearl millet, and rice.

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