Agriculture Reference
In-Depth Information
higher temperatures during growth and development, can delay ripening.
However this delay did not occur via a direct effect on the enzymes as-
sociated with cell wall degradation. In apples, treatments of 38 and 40 °C
for 2-6 days did not have marked effects on respiration, although ethylene
production was reduced.
3.2.9 QUALITY PARAMETERS
Flavor is affected by high temperatures. Apple fruits exposed to direct
sunlight had a higher sugar content compared to those fruits grown on
shaded sides increase in 10 °C increase in growth temperature caused a
50% reduction in tartaric acid content and malic acid synthesis is more
sensitive to high temperature exposure during growth than was the syn-
thesis of tartaric acid. Fruit firmness is also affected by high temperature
conditions during growth. Changes in cell wall composition, cell number,
and cell turgor properties were postulated as being associated with the
observed phenomenon.
3.2.10 ANTIOXIDANT ACTIVITY
Antioxidants in fruit crops can also be altered by exposure to high temper-
atures during the growing season. In 'Kent' strawberries grown in warmer
nights (18-22 °C) and warmer days (25 °C) had a higher antioxidant ac-
tivity than berries grown under cooler (12 °C) days. The high tempera-
ture conditions significantly increased the levels of flavonoids and, con-
sequently, antioxidant capacity. Higher day and night temperatures had a
direct influence in strawberry fruit color. Berries grown under those condi-
tions were redder and darker reported by (McKeon et al., 2006; Wang and
Zheng, 2001).
3.2.11 PHYSIOLOGICAL DISORDERS AND TOLERANCE TO
HIGH TEMPERATURES
Frequent exposure of apple fruit to high temperatures, such as 40 °C, can
result in sunburn, development of watercore and loss of texture
(Fig. 3.4).
Moreover, exposure to high temperatures on the tree, notably close to or at
