Agriculture Reference
In-Depth Information
15.5
IMPACT OF CLIMATE CHANGE ON SOME FRUITS
15.5.1 APPLE, APRICOTS AND CHERRIES
Higher temperatures during autumn are causing sunburn and poor de-
velopment of color affecting marketability in apples, apricots and cher-
ries. Pre-harvest stresses predispose the fruit to physiological disorders
whichappear long after harvest. Heat absorbed by fruit is related to fruit
surface temperature and depends on light intensity. In Washington state
USA, during 2003 season, apple fruit temperature increased to more than
45 °C for at least 15 min in 39 days during fruit growth and maturity in
June-September. Although air temperature varied from 26-37 °C, the fruit
surface temperature varied between 38 °C and 48 °C. Sunburn (Necrosis
and browning) was largest source of cullage and up to 25% fruit was af-
fected and rendered unmarketable (Schrader et al., 2003). It was also ob-
served that high temperatures in field increased incidence of 'Fuji stain'
and 'lenticel marking' after harvest in many apple cvs. In cv. 'Jonagold,'
bitterpit incidence (which is known to be caused due to calcium deficien-
cy) increased and fruit had blotchy skin appearance with irregular color
development due to high temperature and water stress just before harvest.
Watercore in 'Honeycrisp' apples and splitting of 'Fuji' apples were also
noticed due to water stress and high temperature before harvest. 'Granny
Smith' apples are generally susceptible to Sunscald and it develops during
cold storage. Losses due to Sunscald were higher during the years when
air temperatures in field were higher than usual.
With the increase of hailstorms as a possible result of global warming,
fruit crops are increasingly grown under hailnets near Bonn in Germany.
This results in lesser fruit quality in terms of coloration, fruit mass, firm-
ness, starch and taste, that is, lower sugar and acid, and vitamin content
under hailnet due to altered microclimate and light deprivation. Under the
translucent, 'white' hailnet, humidity was increased by 6%, air tempera-
ture reduced by 1.6 °C, soil temperature increased by 0.5 °C and light
reduced by 11-15% resulting in lesser fruit quality (2.5% less sugar and
less taste). Reflective mulches of synthetic material (trade name 'Exten-
day' and 'Daybright') were tried by
Solomakhin
and Blanke (2007) to
improve fruit quality and light utilization under hailnet. The two reflective
mulches increased light reflection by 2.5-6.3 fold. No differences in fruit
ripening and firmness were observed, but fruit from trees under hailnet
