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Crop ideotype

  • Crop ideotype means model plant type or ideal plant type.
  • An ideotype may be defined as model plant which has all such characteristics that are considered ideal for the given environment.
  • In the other words such plants have most of characteristic to produce high yield or better quality when variety is developed from such plants.

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Traits used to construct ideotype plants

1. Morphological and anatomical traits:

    • Plant height- taller plants lodge when higher N is given, therefore, dwarf plants is considered ideal.
    • Erect leaves helps in light penetration to lower canopy depth, therefore, erect leaf is ideal for most crops
    • Thick leaves- more photosynthesis and ideal for good yield
    • Plant height, leaf size, leaf thickness, leaf orientation, stomata frequency etc comes under morphological and anatomical traits to construct ideotype plants.

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Traits For ideotype

  • 2. Compositional traits:
  • Concentration of certain biochemical in plant tissue is helpful for producing better yield and quality in certain environment. For example level of proline or ABA is good for producing drought resistance crop.
  • 3. Process rate traits:
  • Rate of photosynthesis and respiration determine yield. Therefore, plants such have high photosynthesis rate and low respiration rate are ideotype.
  • 4. Process control traits:
  • Rubisco enzyme control Calvin cycle of photosynthesis, therefore, higher level of Rubisco is ideal traits for constructing ideotype plants. There are several such enzymes which control various process. Therefore, this trait is used to construct ideotype plants.

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Ideotype of some crops

  • RICE
  • Shorter Culm length (plant height 100 cm or less)
  • Greater Culm diameter, which increases Culm strength.
  • Lower relative internodes elongation under heavy N application
  • Short, thick erect leaves of medium width
  • High tillering capacity
  • More panicles per unit area
  • High harvest index

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Ideotype of crops

  • Wheat:
  • Short strong stem
  • Erect leaves
  • Large and erect ears
  • Presence of awns
  • Single Culm or less tillering
  • Maize

1.Stiff vertically oriented leaves above the ear

2. Maximum photosynthetic efficiency

3. Efficient translocation of photosynthates into grain.

4. Short interval between pollen shed and silk emergence

5. Small tassel size

6. Photoperiod insensitivity

7. Longer grain filling period

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Economic and biological yield

  • Economic yield:
  • Economic output ( marketable product) per unit area is called economic yield.
  • Yield of rice, wheat and maize ( t/ha)
  • Yield of potato tuber (t/ha)
  • Yield of tobacco leaf and yield of millable cane in sugarcane are the examples of economic yield.
  • Biological yield:
  • Yield of whole biomass produced by the crops. It includes grain as well as straw yield. Root yield is generally not taken as biological yield.
  • Harvest Index:
  • It is the ratio of economic yield to biological yield. It is unit less. It represent the proportion of biological yield that converted into economic yield. Harvest index 0.5 means 50% of biomass is economic yield.

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Harvest index of some crops

CROPS

HARVEST INDEX

RICE

0.4-0.55

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WHEAT

0.25-0.45

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MAIZE

0.4- 0.5

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PPOTATO

0.82-0.86

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SUGARCANE

0.85

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Crop density and Optimum Plant Population

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  • 1. What is crop density ?
    • Number of plants per unit area

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2. What is optimum plant population ?

    • No of plants per unit area that would produce maximum yield.

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Response of plant density on Crop yield

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  • Effect of density on the yield of individual plants as well as on crop community.

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  • Asymptotic and parabolic response of plant density on crop yield

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Factors affecting optimum plant density.

  1. Size of plants
  2. Tillering/branching
  3. Lodging
  4. Reduction of fruit set/ barrenness
  5. Time of sowing
  6. Soil fertility
  7. Irrigation