Agriculture Reference
In-Depth Information
18.3.1 EFFECT OF HIGH TEMPERATURE
a) On Quality
• Flavor is affected, for example, higher sugar content and lower or-
ganic acids of apple groups.
• Firmness two times more in crops grown under high temperature
due to change in cell wall composition, cell number and cell turgor
properties.
• Increase in moisture content and certain fatty acids like Palmitic,
oleic, etc.
• Higher concentration of minerals like Ca, Mg, Cu and K due to less
water movement through crop.
• Increase in antioxidant activity (flavonoids) in berries and but de-
crease in vitamin content.
b) Physiological disorders
• Tomatoes growing at >30 °C temperature affects their color develop
(yellowish white color rather than red), cause softening, increased
respiration rate and ethylene production.
• Fruits exposed to 40 °C have induced metabolic disorders, fungal
and bacteria invasion.
• Greater than 40 °C results in Sun burn of apples, water core and loss
of texture and decreased tolerance to low temperature of apple on
storage.
• Due to delay in winter, yields dropped significantly in crops like
cauliflower, soybean.
18.3.2
EFFECT OF CO
2
EXPOSURE
Composition of air (78% N, 21°% O, 0.93% Ar and 0.03% CO
2
) gets
changed due to climate change resulting in Green house combination ef-
fect of water vapor, CO
2
and minute amounts of other gases like (CH
4
,
Nitrous oxide and Ozone) which absorb radiations leaving earth's surface.
CO
2
or other gases absorb earth's infrared radiations thus trapping heat
resulting in global warming. Their effect on crops is:
• Alter plant tissues in tenure of growth and physiological behavior.
• Photosynthesis, biomass product, sugars and organic acid content,
Stomatal-conductance, firmness, yield, light, water, nutrient use ef-
ficiency and plant water potential.
