Photoperiodism Video Lecture | Science & Technology for UPSC CSE

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today we are going to talk about
photoperiodism let us understand the
meaning of the word it has towards photo
and paradism photo means light and
period is a means duration let us assume
this to be a floral bird which is
exposed to the sunlight for specific
duration of light so when light falls on
the floral bird the floral bird opens up
and it does the flowering so what it
simply means under the impact of light
flowering took place and this impact we
call it as photo video ISM so how can we
define photoperiodism let us understand
response of plant to the relative length
of light and dark period with respect to
initiation of flowering
it means the floral bird gets specific
amount of light so that it opens up and
does the flowering we need to understand
the term photoperiodism was given by two
American plant breeders that is Garner
and Allard these are the two American
plant breeders who came up with the term
photoperiodism in 1930 they worked on
Maryland in memos which is a tobacco
variety we need to understand one most
important term that is called as
critical photo period so friends
whenever we talk about this word
critical critical means most important
it must have that much quantity or
quality of light force critical photo
period minimum duration of light
required to induce flowering for example
let us assume there is the floral bird
now this floral bird requires a minimum
of 10 hours of light if this world bird
has to do flowering
it must get minimum 10 hours of light
let us assume if it gets more than 10
hours of light
it means the floral but we'll be happy
but if it gets less than 10 hours of
light means no flowering will take place
so the 10r condition becomes the
critical photo period for this floral
bird based on this we have three types
of plant we call it as LD p s DP and BN
P so there are three types of plants
with respect to the amount of light or
darkness required L DP s DP n dnp LDP is
long-day plant as DP short-day plant and
en face de neutral plant how to define
LD p flowering is induced under long day
length condition and in s DP flowering
is induced and a short day length
condition in d NP the flowering is not
dependent on the length of light LT p
can also be called as long day length or
short night length plant as DP can also
be called as short day length or it must
get long night length so they are called
as long light plants also the LP is
independent of light so l DP can be
called as summer variety and s DP can be
called as winter variety and the NP does
flowering close dear for example of
LDP's p latch wheat reddish beet let use
mentha or P etcetera for LTP we have
cosmos the earlier marigold
chrysanthemum xanthium viola swear bean
etc for DLP we have koo kumba tomato
sunflower rose
shoofly catharanthus roseus so these are
the examples of DNP so LTP is summer
variety let us assume a plant with a
floral birth exposed to the sunlight and
flowering takes place but the question
is is only sunlight responsible for
flowering no
has to be something in the floral bird
which gets activated on exposure to
sunlight so there was a scientist in the
name of cash latch Jan the 1935 he
suggested one hypothetical hormone
Florie gem and this hypothetical hormone
foraging is responsible for flowering
it's the hypothetical hormone friend it
means it has not yet been isolated or
discovered let us understand LDP sdp and
DNP with respect to graph this is
critical length 12oz night and 12oz day
there are three conditions with respect
to flowering let us assume this is
shaded portion is the area exposed to
the light in the third you can see
little bit light it is due to sudden
flash of light during night time so in
the first condition we see that the
first and the second one first does the
flowering second no flowering and third
of the flowering and in the second
condition middle does the flowering a
third all flowering takes place so this
can be called as long day plant and this
is called a short day plant the last one
on flowering it is called as day neutral
plant hope you have understood the
concept of photoperiodism to subscribe
to the channel friends hit a like if
your water should be concept of
flowering thank you very much