Agriculture Reference
In-Depth Information
for good fruit set. Moreover there is lack of diversity in pollinizing cul-
tivars as mainly Golden Delicious and Red Gold are being predominant-
ly used which have attained biennial bearing tendency and their bloom
seldom coincides with the flowering period of Delicious cultivars. The
population of natural pollinators has gone down due to indiscriminate use
of pesticides and deterioration in ecosystem. Managed bee pollination is
very limited and available bee hives during bloom hardly meet 2-3% of
the demand. All these factors have lead to poor fruit setting of Delicious
(Kjøhl et al., 2011).
3.2.7 EFFECT ON PRE-COOLING
Fruit crops are generally precooled after harvest and before packing opera-
tions. Cooling techniques have been used to remove field heat from fresh
produce, based on the principle that shelf-life is extended 2 to 3 fold for
each 10 °C decrease in pulp temperature. Rapid cooling optimizes this pro-
cess by cooling the product to the lowest safe storage temperature within
hours of harvest. By reducing the respiration rate and enzyme activity,
produce quality is extended as evidenced by slower ripening/senescence,
maintenance of firmness, inhibition of pathogenic microbial growth and
minimal water loss (Talbot and Chau, 2002). Rapid cooling methods such
as forced-air cooling, hydrocooling and vacuum cooling demand consider-
able amounts of energy. Therefore, it is anticipated that under warmer cli-
matic conditions, fruit and vegetable crops will be harvested with higher
pulp temperatures, which will demand more energy for proper cooling and
raise product prices.
3.2.8 FRUIT RIPENING
High temperatures on fruit surface caused by prolonged exposure to sun-
light hasten ripening and other associated events. One of the classical ex-
amples is that of grapes, where berries exposed to direct sunlight ripened
faster than those ripened in shaded areas within the canopy. For fruits ex-
posed to direct sunlight, pulp temperatures reached 35 °C and required 1.5
days longer to ripen than those than grew in the shade (Woolf et al., 1999).
Cell wall enzyme activity (cellulose and polygalacturonase) was nega-
tively correlated with fruit firmness, indicating that sun exposure, that is,
