1. Juvenility ..,..
• A seedling passes through different stages in its life
cycle. These stages are embryonic growth, juvenility,
maturity, senescence, and death.
• Juvenility is a developmental stage in seedling
plants during which it is unable to induce flowers.
• The length of juvenility varies between plants. The
annuals have very short and perennial have long
juvenile period.
Table - Juvenile period of some plants
Juvenile period
20-30 days
1 year
4-8 year
5 Year
5-10 year
45 days
1 year
60 days
80 days
Characteristics of Juvenility
Leaf Form- Leaf is vigorous in juvenile phase. Le' l'ornt
morphology also differ in juvenile phase of some plants
like Acacia sp.
Growth Form - Juvenile shoot growth appears whip
like. The shoot grows parallel to main stem. Such
Plant
Rose
Grapes
Apple
Mango
Citrus
Okra
Banana
Tomato, brinjal
Cucumber
2. .¥ .
shoots are known as water sprout, e. g. Citrus, Guava
etc.
Presence of thorns- Some fruit plant seedlings show
thorns in juvenile phase and these thorns disappears
when attain adult phase. Example- Apple, Pear, Citrus
etc.
....
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Leaf Retention - In juvenile phase plant do not f
leaves throughout the year. Whereas, it falls in adult
phase or maturation phase.
Root emergence - In propagation use juvenile phase
plant parts the root emergence faster then mature
portion of plant.
ii
Bud- A bud is an immature shoot system which .
often surrounded by protective scale leaves. The bud
develops into a lateral branch, a flower or an
inflorescence. These buds develop into flower or
inflorescence is much desire aspect in fruit
production. The development stages in flowering is as
under-
4. _,:,.,+--+-+---+---' o-----Apical
meristem
lntemode
l,t£--::,,..,..,,_- Bud primordium
,.,, Vascular tissue
(xylem & phloem)
flower induction. For bud differentiation to occur
there is enhanced cell division in the central zone
below the apical part of the meristem. Due to cell
division, there is differentiation of parenchyma cells
which surround the meristem, into flower primordia.
2.Initiation - In second initiation of flower formation
takes place.
3. Flower development- It includes length of time frc HORTICT'LTtffi[.
induction to bloom. During this period the flower is genera11y ""
receptive to pollination. Opening of flower (anthesis) is the final
stage of development.
A flower is a modified reproductive shoot, basically a stem with
an apical meristem that gives rise to leaf primordia.
5. Table - flower bud differentiation and flowering i
some important fruit crops
Fruit Crop Bud differentiation Flower opening
Apple June-July Next spring
Peach June -July Next spring
Pear July August Next Spring
Mango October Next spring
Types of Bud
I.Simple Bud- It grows into vegetative shoot. It is
also known as leaf bud.
2.Mixed Bud - It grows into a shoot with a flower. It
is also known as flower bud.
3.Compound Bud - It grows into both leaves and
flowers.
Factors influencing flower bud differentiation
I.Endogenous factors noRnm.Tt,< E
a)Carbon: Nitrogen ratio (C:N ratio) - High ratio of
carbohydrates to nitrogen favours flowering. In young plant,
heavy application of nitrogen which lowers C:N ratio delays
flowering. The plant which are old, weak and having higher
C/N ratio flowers heavily. With respect to C/N ratio, there
may be four situations, such as:
i) High nitrogen and low carbohydrates - flower farms
ii)High nitrogen and enough carbohydrates - flower forms
6. iii)Moderate nitrogen as well as carbohydrates - Good growth
and abundant flower formation.
iv)Low nitrogen and high carbohydrades - Formation of only
few buds.
b) Genes - When plants undergo phasic change from juven_
to adults, eafi gene synthesizes. The gene is responsible for
truncating juvenile and adult phases which induces early
flowering. The HST(HASTY) gene promotes juvenility in plants.
2. Environmental factor
Temperature
Temperature is main environmental factor which is associated
with flowering. Due to availability of a particular temperature in
spring season, flowering occurs at the same time each year.
Exposure of plants to lowtemperature favours flowering.
Biennial plants like carrot, celery, cauliflower, cabbage, turnip
etc. upto exposed to O to 1 o0
c temperature come into flowering.
This is known as vernalization. In these plants, low
temperature requirement is commonly known as chilling
requirement. They have chilling requirement below 7° C for
about 4-60 days for the bud to bloom in spring.
Photoperiod
Some plants flowering only when their photoperiodic
requirement is fulfilled. According to photoperiod plants are
categorised into three broad categories as under:-
l)Long day plant (LDP): - flowering occurs only if day length
is 12 hrs or more than 12 hrs.
2)Short day plant (SDP): - In these plants flowering occurs
when day length is less than 12 hrs.
3)Day Neutral Plant (DNP): - In these plants flowering is not
regulated by day length.
7. Light IIORTICT'LTIIRE
Gll lllJI
Light intensity, duration as well as quality influences
bud differentiation and flowering. Plant receiving high
light intensity flowers properly than low light ones.
That's why outer fruit tree branches have more fruiting
than the inner ones.
The red light (Sunlight) promotes flowering while far
red light inhibits. So, quality of light also affects the
flowering.
8. 3. Managemental Factor -
#.
TJORTJCrLTITRL
i) Nutrients nutrients decide vegetative or
reproductive growth of the plant. Nitrogen increases
the vegetative growth of the plant. And it favours the
carbohydrates utilization of the plant. Phosphorus
works in plant as protein synthesis, cell division;
potash in translocation of sugar. Other nutrients
also involve in flowering and bud differentiation.
ii) Moisture - Non availability of moisture extends the
time of flower bud differentiation. Flower primordia
is less in water deficit conditions.
