Agriculture Reference
In-Depth Information
Apple fruits exposed to direct sunlight had a higher sugar content com-
pared to those fruits grown on shaded sides (Brooks and Fisher, 1926).
Grapes also had higher sugar content and lower levels of tartaric acid
when grown under high temperatures (Kliewer and Lider, 1970). Coombe
(1987) observed that a 10 °C increase in growth temperature caused a 50%
reduction in tartaric acid content. Kliewer and Lider (1970) and Lakso and
Kliewer (1975) verified that malic acid synthesis was more sensitive to
high temperature exposure during growth than was the synthesis of tar-
taric acid. 'Hass' avocados grown under high ambient temperatures (45
± 2 °C), had higher moisture con- tent at harvest than fruit grown under
lower temperatures (30 ± 2 °C) (Woolf et al., 1999). They also noted that
higher temperature influenced oil composition, where the concentration of
certain specific fatty acids increased (e.g., palmitic acid by 30%) whereas
others did not (e.g., oleic acid). Avocados with higher dry matter content
take longer to ripen which could pose a serious problem for growers plan-
ning to market their fruits immediately after harvest (Woolf and Ferguson,
2000; Woolf et al., 1999). Mineral accumulation was also reported to be
affected by high temperatures and/or direct sunlight. 'Hass' avocado fruits
exposed to direct sunlight showed higher calcium (100%), magnesium
(51%) and potassium (60%) contents when compared to fruits grown un-
der shaded conditions (Woolf et al., 1999).
Wang and Zheng (2001) observed that 'Kent' strawberries grown in
warmer nights (18-22 °C) and warmer days (25 °C) had a higher antioxi-
dant activity than berries grown under cooler (12 °C) days. The investiga-
tors also observed that high temperature conditions significantly increased
the levels of flavonoids and, consequently, antioxidant capacity. Galletta
and Bringhurst (1990) verified that higher day and night temperatures had
a direct influence in strawberry fruit color. Berries grown under those con-
ditions were redder and darker. McKeon et al. (2006) also addressed the
effects of climate changes in functional components. They verified that
higher temperatures tended to reduce vitamin content in fruit and vegeta-
blecrops. Frequent exposure of apple fruit to high temperatures, such as
40 °C, can result in sunburn, development of watercore and loss of texture
(Ferguson et al., 1999). Moreover, exposure to high temperatures on the
tree, notably close to or at harvest, may induce tolerance to low-temper-
atures in postharvest storage (Woolf et al., 1999). In general, higher tem-
peratures increases pest and disease activity, alter their development rate,
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