PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS))

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PRINCIPLES OF CROP PRODUCTIONABT-320(3 CREDIT
HOURS))

• LECTURE 4
• LECTURE-WISE COURSE BREAKUP
• MATING SYSTEMS IN SEXUALLY REPRODUCING PLANTS
• BIOMETRICAL GENETICS AND PLANT BREEDING
• FACTORS AFFECTING CROP PRODUCTION

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MATING SYSTEMS IN SEXUALLY REPRODUCING PLANTS

• Three mating systems
• Random mating
• Inbreeding
• Outbreeding
• Can be seen in sexually reproducing populations.
  Accordingly, the genetic structure of the
  populations will also be different.

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RANDOM MATING

• This is the condition in which each male gamete
  is likely to get equal chance to fertilize a
  female gamete. This phenomenon is called
  panmixis. The only factor that acts in the
  process of fertilization is chance. Under such
  conditions, the population will be a balanced
  group of the different genotypes and phenotypes
  possible, distributed according to theoretical
  ratios of probability.

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INBREEDING

• Inbreeding is the phenomenon in which gametes
  from the same genetic source (gametes from the
  same genetic structure) get higher chance to mate
  at the time of fertilization. Many crop plants
  naturally promote inbreeding (e.g., rice, wheat
  and pulses). Inbreeding results in the
  improvement of homozygosity in plant populations.
  Self-pollination (autogamy) promotes inbreeding.
  There are several mechanisms in nature that
  accomplish autogamy including bisexuality,
  homogamy and cleistogamy.

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BISEXUALITY

• This is the condition in which both the male
  (androecium) and female (gynoecium) reproductive
  structures are produced by the same flower.
  Bisexuality promotes self-pollination. Capsicum,
  pulses, are the examples of bisexual flowers.

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HOMOGAMY

• This is the condition in which both the male and
  female reproductive parts of a bisexual flower
  mature simultaneously. The androecium and
  gynoecium mature at the same time to promote
  self-pollination. In such flowers, mostly
  pollination takes place before the opening of
  flower.

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CLEISTOGAMY

• In some cases the flowers never open and
  pollination takes place in the bud condition.
  This is called cleistogamy. As a result of this,
  chance of cross-pollination is eliminated.
  Arachis hypogea is an example.

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OUTBREEDING

• Outbreeding is the phenomenon in which gametes
  from different parental sources get higher chance
  to unite at the time of fertilization. There are
  many crop plants which show cross pollination
  (allogamy). E.g., coconut, maize, sunflower and
  pearl millet. The following mechanisms are
  involved to promote cross-pollination in such
  plants
• Monosexuality
• Dichogamy
• Heterostyly

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MONOSEXUALITY

• This is the condition in which male and female
  flowers are separate. Both the types of flowers
  may be seen on the same plant (monoecy, e.g.,
  coconut) or on different plants (dioecy, e.g.,
  papaya).

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DICHOGAMY

• In many bisexual flowers, androecium and
  gynoecium mature at different times so as to
  promote cross-pollination. This phenomenon is
  called dichogamy. It may be of two types
  protandry in which androecium (male reproductive
  organ) matures first and protogyny (female
  reproductive organ) in which gynoecium matures
  first. Both protogynous and protandrous varieties
  of walnut have been reported.

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HETEROSTYLY

• This is a condition in which two or more types
  of styles are seen in some plants. Accordingly,
  different types of staminal filaments are also
  seen. In flowers with long styles, short staminal
  filaments are seen, whereas in flowers with short
  styles long staminal filaments are present.
  Primrose shows heterostyly.

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BIOMETRICAL GENETICS AND PLANT BREEDING

• FACTORS INVOLVED IN AN EXPERIMENT
• Experiments related to the screening of plants
  are conducted either in net houses or green
  houses under controlled conditions or in the open
  field under technical supervision. When a field
  experiment is designed, many factors like soil
  heterogenerity, replications, border effect and
  randomization are taken into consideration.
• Replication
• Randomization
• Local Control

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REPLICATION

• The most important factor in the conduct of an
  experiment is the replication of the treatments.
  The repeated application of the treatments under
  investigation is known as replication. It is
  possible to calculate an estimate of error of the
  experiment from replicated trials. Experimental
  error gets reduced with the increase in the
  number of replications. But, in practice, an
  optimum number is to be fixed for each type of
  experiments. The number of replications will
  depend on the degree of accuracy required,
  availability of land and the quantity of seeds
  available.

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RANDOMIZATION

• Random allocation of treatments to various plots
  is necessary for an objective comparison between
  treatments. By randomization, better estimate of
  the average impact of environmental factors on
  the outcomes becomes possible.

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LOCAL CONTROL

• This is the grouping of homogenous experimental
  units into blocks and the study of within block
  variations. The variations within block are
  caused by soil heterogeneity and other local
  effects. One such effect is known as border
  effect. It is the harmful or useful effect
  enjoyed by border lines of the experimental
  plants. To avoid border effect, separate border
  rows of plants are grown surrounding the
  experimental plots.

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FACTORS AFFECTING CROP PRODUCTION
Agricultural production, including food and other
crops and livestock husbandry, is determined by
the interaction of farmers with natural
resources - biophysical framework of soils,
water, temperature, flora and fauna
traditional practices government policies
(e.g. land tenure, marketing, animal welfare,
labour relations) international trade
agreements public opinion and concerns
environmental fluctuations.
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THE END