Agriculture Reference
In-Depth Information
Functional component in fruit crops can also be altered due to expo-
sure of fruits to high temperatures during the growing season. It has been
observed that 'Kent' strawberries grown in warmer nights (18-22°C) and
warmer days (25°C) contain higher antioxidant capacity than fruits grown
under cooler (12°C) days (Wang and Zheng, 2001). This increase in an-
tioxidant capacity was due to increase in flavonoid content due to high
temperature condition. McKeon et al. (2006) also addressed the effects of
temperature and verified that higher temperature tended to reduce vitamin
content in fruit.
High temperature and/or direct sunlight also influenced the mineral
accumulation in fruit crops. For example, 'Hass' avocado fruits exposed
to direct sunlight during growing period contain higher calcium (100%),
magnesium (51%) and potassium (60%) contents when compared to fruits
grown under shaded conditions (Woolf et al., 1999).
Fruit coloration may be severely affected because the biosynthesis of
coloring pigments is strongly influenced by the temperature. The nutri-
tional value and antioxidant potential of fruit may be affected due to de-
crease in skin pigments. The deep red color development in apple is a
result of low temperatures during the night in autumn, just before harvest-
ing. If the temperatures are not low enough, most apples fail to turn into
their specific red shades. Besides, higher day and night temperatures have
a direct influence in strawberry fruit color development. Berries grown un-
der those conditions are redder and darker (Galletta and Bringhurst, 1990).
16.2.2 CARBON DIOXIDE
The atmosphere of earth consists chiefly of 78.1% nitrogen and 20.9%
oxygen, with carbon dioxide (0.031%) and argon (0.93%) comprising next
most abundant gases. Among these, nitrogen and oxygen are not consid-
ered to play an important role in global warming as these gases are virtu-
ally transparent to terrestrial radiation. While, carbon dioxide, water vapor
and minute amounts of other gases (methane, nitrous oxide and nitrous ox-
ide) that absorb the earth's infrared radiation, trapping heat are responsible
for global warming. Since a significant part of all the energy emanated
from earth occurs in the form of infrared radiation, increase in CO
2
con-
centration mean more energy will be retained in the atmosphere, contribut-
ing to global warming (Lloyd and Farquhar, 2008). As a consequence of
