Tropical and subtropical vegetables (2+1)

Physiological disorders of cucurbits

Pillow:
                           It is a fruit disorder of processing cucumber due to low calcium level in the tissue. In this disorder, an abnormal white styofoam like porous textured tissue is formed in the mesocarp of the fleshy harvested fruits. Vascular tissue with some pillow areas may collapse and become necrotic.
Leaf silvering:
                            It is a physiological disorder of summer squash (cucurbita pepo). This disorder occurs due to moisture scarcity. The leaves become silver coloured and contain less chlorophyll; photosynthesis is hampered in the silvered leaves.
Unfruitfulness in pointed gourd:
                           Pointed gourd is a dioecious cucurbit. So, male and female plants are separate. Female plants produce the fruit whereas male plants act as a pollen donor. So required number of male plants should be there in the population of female plants to ensure adequate pollination, fertilization and fruit set. A common problem is met with where pistillate flowers in female plants are shed due to lack of pollination and fertilization. In some cases, ovary of the unfertilized flower may flow a bit due to parathenocarpic stimulation which also abscise after a few days.
Control:
                           Male plants must be grown in the field along with the female plants at the rates of 10-12 male plants per 100 female plants to ensure adequate pollination and fruit set. Hand pollination may be done successfully to achieve fruit set. Hand pollination to the female flowers should be done in the early morning hours because stigma receptivity decreases with an advancement of the day.
Delay in fruit ripening:
                           This problem is particularly important in muskmelon and watermelon. Delay in repining is sometime associated with less sweetness and cracking of fruits which occur due to high moisture level and temperature fluctuation at ripening stage.
Control:
                           Irrigation should be stopped at the ripening stage to hasten ripening. Sowing time should be adjusted in such a way that fruits ripe in hot and rainless condition which hastens ripening and at the same time improve sweetness of the fruits.