Climate change is affecting many aspects of the planet,
including the production of citrus fruits. Citrus fruits are a staple food in
many countries and are grown for their delicious taste and nutritional
benefits. However, the changing climate is making it increasingly difficult for
growers to produce high-quality citrus fruits. In this article, we will explore
the effects of climate change on citrus fruits and what can be done to mitigate
these impacts.
Under the background of global warming, the citrus yield may
be affected by climate risk in subtropical regions of China. Soil erosion in
citrus orchards caused by increasingly frequent and intense extreme
precipitation is the main cause of productivity decline
Citrus Trees and Climate Change
Citrus, a warm climate fruit tree in the Rutaceae family,
Citrus require specific temperature between 10-35o C without freezing nights to
produce its yield, however, there are a few varieties could tolerate low
temperature as low as 3oC for short time, like Mandarin oranges, and Poncirus
trifoliate could tolerate freezing due to it is the only deciduous variety in
Citrus, therefore it's the proper rootstocks for citrus cultivation in cold
regions, also, fruit quality is very sensitive to temperature.
Effect of Temperature
Citrus producing regions are commercially located in between
40° north and south latitude where the minimum temperature is generally more
than-4 ºC. The optimum temperature for citrus growth is 25-30o C with the
maximum rate of photosynthesis occurring at 30o C.
Effect of Low Temperature
Freezing temperatures are the most restrictive factor for
citrus cultivation, therefore, citrus cultivation must be avoided in any region
with winter frosts and low temperatures to (-4o C)
Negative Effects of low temperature on citrus tree:
1. At (-1.7o C) young fruits and flowers have died,
2. Mature fruits are damaged at (-2o C).
3. Most citrus trees are defoliated at (-4.4 to -5.6o C).
4. Main branches are deleterious at (-6.7o C).
Effect of high temperature High-temperature effect on
different growth stages of citrus trees, the adverse effect of temperature on
citrus fruit occurs when crosses its limits (above 40o C), Under conditions of
high day temperature (more than 40o C) with low humidity the vegetative growth
of citrus trees reduced to minimum levels or stopped completely. In
Mediterranean climate the High temperatures combined with low humidity increase
fruit sunburn particularly in outer canopy of trees, also, high day temperature
broken pigments such as anthocyanin and carotenoid in pericarps of fruits
particularly late varieties like Valencia orange which reduce fruit quality.
The effects of high temperature have been noted during both vegetative and
reproductive growth stages in various citrus varieties occur as direct injuries
or indirect effects through disturbance of metabolic processes as follow:
- Reduced vegetative growth
- Fluctuation flowering time and longevity.
- Decreased total yield through increases fruit drop.
- Reduce fruit quality (affect total sugars/ acidity ratio).
- Disorders (sunburn and regreening in late varieties).
- Metabolic processes (broken pigments like anthocyanin)
Fruit sunburn:
The sunburn is a result of a rising in the fruit surface
temperature rather than the extension of the fruit development period. Effect
on flowering Under Mediterranean conditions, citrus trees flowering from March
as one time yearly, however flower induction, flowering intensity, and duration
are correlated with temperature during the flowering period. Warming weather in
autumn and winter delaying the budding and flower initiation, consequently
delay flowering, reduce flower number, and fruit set. High temperature during
flowering stage increased abortion of fruit set in mandarin (Citrus unshiu) due
to the negative effect of high temperature on type of inflorescences and
growing of different parts of flowers.
Effect on crop yield
Due to climate change and rising day temperature,
consequently increased night temperature which negatively affect citrus
productivity by decreasing photosynthetic function with reducing dry matter
production, also, climate scientist expected increase night temperature at a
quicker rate than day temperatures in the next decade due to less radiant heat
loss because of increased cloudiness.
Effect on harvesting
Due to climate change the harvesting period of citrus
changed, some varieties earlier and another later. Cold night temperature
increase anthocyanin and carotenoid in pericarps which accelerate peel
coloring, however, warm days in autumn delay peel coloring, so, the harvesting
period delayed than optimum time.
Negative effects of climate change on fruit quality:
There are various negative effects of climate change on
fruit quality as follow:
1. Reduce total
sugars acidity ratio.
2. Fruit rigidity decreased and increased pulp softening.
3. Spread sunburn particularly in easy peeling varieties
like mandarins.
4. Reduce fruit quality.
One of the biggest effects of climate change on citrus
fruits is the increase in temperature. Citrus trees require a specific range of
temperatures in order to grow and produce fruit. Higher temperatures can cause
fruit to mature faster, which can result in smaller fruit size and lower
yields. Additionally, high temperatures can also increase the risk of diseases,
pests, and other stress factors that can harm the health of the tree and reduce
its ability to produce fruit.
Another effect of climate change on citrus fruits is the
increased frequency and intensity of natural disasters such as hurricanes,
droughts, and floods. These events can cause significant damage to citrus
crops, destroying trees and reducing yields. In addition, they can also
increase the risk of disease and pests spreading, further reducing the
productivity of the crops.
The changing climate is also affecting the distribution of
pests and diseases. As temperatures rise, pests and diseases that were once
confined to certain regions are now able to spread to new areas. This can have
a significant impact on the production of citrus fruits, as the pests and
diseases can quickly spread and cause widespread damage.
In order to mitigate or reduce the effects of climate change
on citrus fruits, growers need to adopt sustainable practices that help protect
the health of their crops. This includes planting more resilient varieties of
citrus trees, using effective pest and disease control measures, and improving
soil health to support the growth of healthy trees. Growers can also use water
management techniques, such as drip irrigation and mulching, to conserve water
and reduce the risk of drought.
Another important step in mitigating the effects of climate
change on citrus fruits is to reduce greenhouse gas emissions. This can be done
by using renewable energy sources, improving energy efficiency, and reducing
the use of fossil fuels.
In conclusion, climate change is having a significant impact
on the production of citrus fruits. However, with the right measures in place,
growers can protect their crops and continue to produce high-quality citrus
fruits for generations to come. By adopting sustainable practices, reducing
greenhouse gas emissions, and improving resilience, we can ensure a bright
future for citrus production in the face of a changing climate.
