Agriculture Reference
In-Depth Information
1.3.4 FRUIT QUALITY
Although, higher temperature regimes generally result in the best qual-
ity fruits, excessively high temperatures for extended periods of time are
known to damage fruits result in delay of fruit maturation and reduction in
fruit quality of grape. High temperatures also reduce color development.
Higher daily temperatures were also related to a decrease in color hue
values, that is, more red fruit. In the case of guava, it has been observed
that red color development on the peel of guava requires cool nights dur-
ing fruit maturation. Varieties like Apple Color guava, which have attrac-
tive apple skin color under subtropical conditions of North India, have red
spots on the skin under tropical South Indian conditions. Observation in
areas suitable for production of red color guava by Rajan (2008) revealed
that the total soluble solids, fruit firmness, and percentage dry mass were
negatively correlated with temperature during fruit growth. However, the
relationship varied with the cultivar (Hoppula and Karhu, 2006). In sub-
tropical and tropical fruit crops, there is a direct effect of the temperature
the maturity and ripening of fruits. When there is sufficient moisture, TSS
of fruit increases with increase in temperature. However, in fruits like pas-
sion fruit, increases in temperature do not increase TSS. Hence, the effect
of different regimes of temperature can be different on different crops un-
der subtropical and tropical environments.
1.3.5 INCIDENCE OF DISEASES AND PESTS
A number of factors affect the pest and disease scenario in fruits. High
temperatures coupled with high rainfall and humidity help in building up
ideal conditions for the growth of a number of disease pathogens. For ex-
ample, the powdery mildew disease in mango caused by
Oidium mangif-
erae
Berthet is a sporadic but serious disease of mango inflorescence that
can cause 80-90% losses of the crop in extreme cases. Optimal disease
development occurs at 10-31°C and 60-90% RH. (Chhata et al., 2006)
reported that high humidity (85-90%), moderate temperatures (maximum
temperature of 25-26°C and minimum of 18-20°C) provided favorable
condition for the initiation of disease. Correlations between weather pa-
rameters like maximum temperature regimes and sunshine hours had neg-
ative correlations with disease development, while minimum temperature,
