Temperature, humidity and light are the important variables
influencing growth and development of grapes. Hot and dry climate
is ideal. Areas with high rainfall are not suitable. The climate
requirements of vinifera are different from those of labrusca
grapes. Mild temperature, not exceeding 35 o C in summer, impairs
the fruiting of vinifera grapes, particularly, in Thompson
Seedless. Higher night temperature (above 25 o C) during ripening
hamper the colour development in coloured grapes.
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Slide 3
Cool nights and hot days even though congenial for coloured
grapes, pink pigmentation development was found in green grapes if
the diurnal differences are more than 20 o C during ripening. Grape
vines are deciduous under temperate conditions and do not show
dormancy under tropical and sub tropical conditions. Basically, it
is a sun loving plant. Excepting coastal humid regions with high
rainfall, climatic conditions varying from temperate to subtropical
and tropical are suitable for grape culture. Temperature, light and
humidity are the climatic variables playing significant roles in
vine growth and development. PreviousNextEnd
Slide 4
High humid conditions result in excessive vegetative growth, in
turn affecting yield and quality. Ripening of berries will be
affected and incidence of pests and diseases will be more. Vinifera
varieties prefer long, warm to hot, dry summers and cool winters.
They need about 60 days of rest in winter, with an average daily
mean temperature below 10C and some freezing temperatures. Shoot
growth begins in spring. Bright sunny days help in development of
sugar in berries. Maturity and ripening in grapes are influenced by
degree-days - heat unit summation. Previous NextEnd
Slide 5
Heat units are calculated by multiplying the mean daily
temperature over and above 10C by the number of days. Certain
amount of heat units is to be attained specific to varieties for
berry ripening and this requirement varies from 1600 to 3500 degree
days. Distribution of rain is important in grape culture. Rains at
blooming time reduce fruit set and during ripening time result in
spoilage of crop. Vines tolerate low temperature or frost during
dormancy period but during spring season, frost damages sprouting
buds. Humidity is a limiting factor for vinifera grape culture, due
to disease susceptibility. Vinefera varieties cannot tolerate high
humidity or rain during harvest. Internal quality is reduced, fruit
cracks when swollen with water, and fungal diseases are far worse.
Thick-skinned, disease tolerant muscadines grow much better in
humid climates. Previous NextEnd
Slide 6
The major banana growing areas of the world are geographically
situated between the Equator and latitudes 20 o N and 20 o S.
Climatic conditions in these areas are mainly tropical, with
comparatively small temperature fluctuation from day to night and
from summer to winter. The banana growing areas of subtropics are
situated between 20 o and 30 o North or South of the equator. The
main climatic characteristic in the subtropics are the wide
temperature fluctuations between day and night and between summer
and winter, the high and the low rainfall which is also poorly
distributed. Previous NextEnd
Slide 7
Bananas perform very well under humid tropical conditions but
can be cultivated successfully even under humid or semi arid
sub-tropical conditions. The growth and yield of most of the
varieties are better at a temperature range of 25-35C though they
can be cultivated at a temperature range of 10-40C. A suitable
banana climate is a mean temperature of 26.67C and mean rainfall of
10 cm per month. There should not be more than 3 months of dry
season. Under cooler climates the crop duration is extended. The
shooting and bunch development gets affected at temperature less
than 10C. Previous NextEnd
Slide 8
The growth of the banana plant responds quickly, within a
matter of an hour or two to changes in air temperature. All growth
ceases as soon as the temperature of the surrounding air falls
below 11 C. As long as the temperature remains 11 C, no growth
whatsoever takes place. As the air temperature rises above 11 C,
growth starts and the growth rate increases gradually at first, and
then with rising temperatures, more and more rapidly. The biggest
increase in growth rate for every degree that the temperature rise
appears to lie between approximately 19 C and 23 C. Previous
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Slide 9
The daily growth at 23 C is, in fact, about double that at 19
C. With further rise in temperature, the growth continues to
increase, but more and more slowly as high levels of temperature
are reached. In the experiments conducted, no falling off or even
leveling off of the growth rate was observed. Previous NextEnd
Slide 10
M ango is very well adapted to tropical and subtropical
climate. It thrives up to an altitude of 1400 m above mean sea
level but fruiting is poor beyond 500 m. It thrives well from
Kanyakumari in Southern India to sub mountainous regions in the
North. The annual mean temperature at which mango thrives best is
around 26.7 o. The optimum temperature for mango is 23.9 to 26.7 o
C. The prevailing temperature affects the expression of sex in
mango i.e., a close association appears between high temperature
and increased percentage of perfect flowers and vice versa. High
temperature by itself is not so injurious to mango, but in
combination with low humidity and high winds affects the growth of
the trees adversely. Previous NextEnd
Slide 11
Mango thrives in places with good rainfall (75 to 375 cm per
annum) and dry season. The distribution of rainfall is more
important than quantity of the rainfall. A dry weather before
blossoming is conducive for profuse flowering. Rain during
flowering washes away the pollens, which adversely affects the
fruit set, and also encourages greater incidence of mango hoppers,
mealy bugs and diseases like powdery mildew and anthracnose that
can damage the crop completely. Cloudy weather with increased
humidity in the atmosphere encourages the incidence of pests and
diseases and interferes with the activity of pollinating insects,
thus adversely affecting fruit set. Previous NextEnd
Slide 12
In areas of excessive rainfall and high humidity, even during
the time of fruit maturity, commercial mango growing may not be
profitable due to the attack of fruit fly. If high temperature,
rainfall and humidity persist throughout the year, there will not
be any distinct phases of vegetative and flowering in the mango
tree thus resulting into poor flower production and fruit set.
Temperature, also governs the flowering and ripening of fruits. In
Kanyakumari, some of the varieties flower and fruit twice a year,
known as off season bearing which is primarily conditioned by the
differences in night and day temperatures and humidity. Strong
winds and cyclones during the fruiting season can play havoc as
they cause excessive fruit drop. Hot winds during summer have an
adverse effect both on fruit and foliage growth. Previous
NextEnd