The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/texts/txtfiles_misc/pot27

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                 -+- The Merry Pranksters from Menlo Park -+-
                               10.1990.01.01.27

                 Marijuana Grower's Handbook - part 27 of 33
                               by pH Imbalance
                             "Advanced Flowering"

                                     from

                         Marijuana Grower's Handbook
                         [Indoor/Greenhouse Edition]
                                 Ed Rosenthal


[pH:This chapter has 21 pages of charts and diagrams that I did not enter,
that are very informative and highly useful.  If you want them, buy the
book.]

   In Part 25 (Flowering), marijuana's photoperiod response was described.
Most varieties of cannabis flower in response to changes in the light cycle.
This is a foolproof method for a plant to determine when to flower when it
is adapted to a particular location.  Every year the ratio of dark to light
remains the same at a particular date.  Scientists think that plants measure
the number of hours of darkness by producing a hormone, tentatively named
florigen.  This hormone has not actually been discovered.  The theory is
that when the level of this hormone reaches a critical level, the plant goes
into its reproductive mode.
   Through simple experimentation, we know some interesting things about
this plant response.  It is a localized response by the plant.  This was
discovered by shading one branch of a plant but leaving the rest of it
without a daily dark period.  Only the branch that was shaded flowered.
(This is a viable technique to use to sex plants).
   Researchers think thatthe hormone is produced by the plant continuously.
However, it is destroyed or metabolized by an enzyme or hormone which is
produced only in the presence of light.  Under natural conditions, the
critical level builds up only with the onset of long nights in the autumn.
When the dark cycle is interrupted by light, even for a few minutes or less,
the florigen is destroyed by the plant and the plant starts the buildup to
the critical level over again.
   The response to different light cycles is a graduated one.  Plants that
initiate flowering at one light/darkness routine flower more heavily when
the amount of darkness is increased.  This response is more pronounced on
plants originating from a higher latitude where the light cycle changes
more.
   Chrysanthemums are also long night-flowering plants, and their growth
patterns have been studied extensively for use by the greenhouse industry.
Researchers found that the largest flowers with the highest total weight
were grown when the dark cycle routine was provided each night.  When the
plants were shaded 6 nights a week, there was a slight diminution of flower
size and total weight.  With each additional unshaded night, flower size and
weight dropped.  [pH:Now, you are probably thinking "That doesn't make one
damned bit of sense!" and you are correct.  I don't know what Ed was
thinking in this instance, so I won't bother to correct THIS error, but if
one reads it, if the plants are shaded for 6 nights a week, they get
smaller.  If you "unshade" them, they also get smaller.  You're screwed
either way, apparently.]
   Cannabis is one of the most widespread plants.  It is naturalized
everywhere from the equator to the arctic.  (Private cannabis gardens have
also been documented as being grown by scientists stationed at outposts in
the Antarctic - it's not illegal there since no country has sovreignty).
The plant has developed many variations on the photoperiod response to
adjust to different climactic and latitudinal conditions.
   Female plants from equatorial or sub-equatorial zones such as Colombia,
southern Mexico, central Africa, and south India are absolute
photo-determinate (APD).  These plants are acclimated to latitudes in which
there is little variation in the light cycle throughout the year.  As long
as the dark period falls below a minimum trigger period, the plant remains
in the vegetative growth cycle.  This can go on for years under continuous
light conditions.  When the dark period lengthens to a trigger point, the
plant changes its growth pattern to sexual development.  If the dark period
falls below the trigger level when the plants are flowering, the plants
easily revert back to vegetative growth.
   APD plants are good candidates to flower and regenerate.  Since they
respond to the light cycle in a relatively simple way, irregular or
interrupted cycles alter growth significantly.  Buds are smaller, leafier,
fluffier, looser, and may run.  They look a bit like low-light flowers.
   Flower size can be increased by allowing the plants to ripen fully, then
placing them in a continuous light regimen for a few days.  Flowering is
triggers again and the plants produce new clusters of flowers.  [pH:Perhaps
Ed didn't write this chapter, because it is repeating too much stuff he's
already said, and besides: That isn't going to increase the flower SIZE, it
will increase the amount harvested.]
   Some cannabis varieties are "relative photoperiod determinate" (RPD).
These plants have a trigger that they respond to under normal growing
conditions, but when they receive an unusual light regimen, they respond to
the change in the light conditions in unusual ways.  For example, an early
flowering indica normally triggers at 10 hours of darkness, but if it is
grown under continuous light and then the darkness cycle is increased to 8
hours, the plant triggers.  Once these plants are triggered, the light cycle
has less affect upon them than upon the APDs.  The developing flowers are
not as sensitive to occasional interruption of the darkness cycle.
   RPD varieties include the  mid- and high-range latitude-adapted plants
including Moroccans and southern Africans, early indicas, commercial hemp
and hybrids developed for early harvest (September or earlier).
   RPD varieties are harder to manipulate using the light cycle.  Plants
placed into flowering do not revert to vegetative growth as easily as APD
varieties.  [pH:Perhaps I'm in a bad mood, but does he have to keep fucking
repeating himself?  This is annoying as HELL!]  The plants are harder to
regenerate.  Light stress promotes hermaphroditism in these varieties.  They
are harder to clone; they take longer and have a lower success rate.
   Most males and some extreme northern varieties including the ruderalis
strains fall into a third category which is not photosensitive at all.  Both
age and development seem to play a role in determining when these plants
flower.  For example, a Hungarian ruderalis developed flowers under
continuous light after 8 weeks.  Most varieties of males indicate under
continuous light after 3-9 months.  Thais and some equatorial sativa males
are exceptions and will not flower until the dark period is increased.
Under 18 hours of light, males indicate sooner than under continuous light.
   Cold may hasten sexual expression but not flower development of some
northern varieties.
   Some varieties, especially indicas, respond to unnatural light cycles by
showing photo-period response disorder.  Genetic females turn hermaphroditic
when exposed to long dark periods during early growth.