Agriculture Reference
In-Depth Information
17.1 INTRODUCTION
Climate on Earth has changed many times during the existence of our
planet, ranging from the ice ages to periods of warmness. During the last
several decades, increases in average air temperatures have been reported
and associated effects on climate have been debated worldwide in a vari-
ety of forums. Due to its importance around the globe, agriculture was one
of the first sectors to be studied in terms of potential impacts of climate
change (Adams et al., 1990). Environmental factors include climate (tem-
perature, wind, and rainfall), air quality, and positional effects both within
a planting and within the tree. Elements such as wind, heavy precipitation,
and frost may result in direct loss of the fruit from the postharvest chain
due to fruit scarring; increased incidence of plant pathogens associated
with high rainfall, especially during flowering (i.e., anthracnose); and loss
of fruit related to freeze damage. Temperature during fruit growth and
maturation may also influence fruit quality by either hastening or delay-
ing horticultural maturity. From preindustrial levels of 280 ppm, carbon
dioxide (CO
2
) has increased steadily to 384 ppm in 2009, and average
temperature has increased by 0.76 °C over the same period. Projections to
the end of this century suggest that atmospheric (CO
2
) will top 700 ppm or
more, whereas global temperature will increase by 1.8-4.0 °C, depending
on the greenhouse emission scenario (IPCC, 2007).
Temperature increase and the effects of green house gases (GHG) are
among the most important issues associated with climate change. High
temperatures and exposure to elevated levels of carbon dioxide and ozone
can affect the production and quality of fresh fruit crops, both directly
and/or indirectly. Temperature increase affects photosynthesis directly,
causing alterations in sugars, organic acids, and flavonoids contents, firm-
ness, and antioxidant activity. Taste of fruit is highly dependent on the bal-
ance between organic acids and soluble sugars, which are predominantly
represented by organic acids (citric, malic and tartaric acids) and sugars
(sucrose, fructose, and glucose), respectively (Medlicott and Thompson,
1985). Another quality trait for fruits is their shelf life, which can vary
with pre as well as postharvest conditions, the best known of which is tem-
perature. However, this attribute can be influenced by conditions during
fruit growth that affect the supply of minerals to the fruit. Special attention
must also be paid to the influence of environmental factors on ingoing fruit
fluxes as well as on the balance between mineral ions in fruits (Ferguson
