crop sci v

• Environmental factors


  Factors that determine the performance of a crop (yield)
• Genotype


  The set of characters in the plant that is inherited from parents. It gives the potential and set limits within which the plant will perform
• Environment


  Determines to what degree the potential of the plant will be expressed
• Environmental factors

  • Abiotic factors
  • Biotic factors
  • Genetic factors
• Abiotic factors


  Non-living environmental factors (e.g., soil, and elements of climate and weather)
• Biotic factors


  Living environmental factors (e.g., insects, microorganisms, man and plants)
• Solar radiation


  Radiant energy from the sun
• Wavelength


  The distance between wave crests (unit: nanometers (nm))
• Frequency


  The number of wave crests or cycles passing a point in space in one second
• Photon


  Discrete units of radiant energy
• Quantum


  Energy carried by photons
• Electromagnetic spectrum


  The known distribution of electromagnetic energies arranged according to wavelengths, frequencies, or photon energies
• Solar radiation


  • Satisfies two very important needs of biological organisms: energy and information
• Photoperiod


  The duration of radiation or daylength
• In the northern hemisphere, the day is longest and the night shortest in the summer solstice (June 22)
• The day is shortest and the night is longest in the winter solstice (December 22)
• Photoenergetic effects


  Radiation serves to drive metabolic reactions or causes chemical transformation
• Photocybernetic effects


  Radiation controls metabolism, growth and development
• Photoperiodism


  Synchronizes development and the rhythmic events in the life cycle with diurnal/dark alteration and the season of the year
• Long days promote stem elongation
• Short days promote formation and growth of tubers (potato)
• Seed germination is promoted by red light but suppressed by far-red and blue
• Stem elongation is promoted by far-red but inhibited by red
• Red promotes leaf and cotyledon expansion after germination
• Flower induction (in photoperiodism) is affected by red and far-red
• Phototropism is regulated by blue and UV-A
• Photodestructive effects


  Effects occur with extremely high-intensity visible radiation or are caused by UV, including photooxidation and photodestruction
• As irradiance increases


  Atmospheric temperature also increases
• High irradiance


  Increases the rate of transpiration
• Too much transpiration may result in closure of the stomata or wilting
• Heliophytes


  Sun-loving plants
• Sciophytes


  Shade-loving plants
• Facultative sciophytes


  Sun-loving plants that can tolerate shade
• Weather


  The state of the atmosphere over short periods of time
• Climate


  All weather conditions that characterize a particular region over a period of time
• Temperature


  How hot or cold the atmosphere is as measured by a thermometer
• Minimum temperature


  Below which a process will not take place
• Maximum temperature


  Above which a process will not take place
• Optimum temperature


  At which a process will proceed with greatest rapidity
• Higher temperature


  Accelerates the rate of development