SPROUTING

Sprout growth begins at the end of dormancy period. Once sprouted, potatoes start loosing weight, their appearance is affected by shriveling and they loose marketability for table and processing purposes. Besides, in seed as well sprouting before the required time is undesirable since the shriveled tubers loose vigour. Sprouting is influenced by several factors and the major factors that influence sprout growth are cultivar, temperature, humidity, light, concentration of CO₂ and O₂ and size of tubers. Difference in the rate of sprout growth is a cultivar character provided all the other conditions are similar. Considerable variation has been observed in the length of the longest sprout and weight of sprouts. The pattern of sprout growth also varies with the cultivar.

Temperature has strong influence on sprout growth. Generally sprout growth does not take place when the storage temperature is less than 4ºC. Sprout growth is observed at 5ºC and increases with increasing temperature. Sprout growth is optimum between 15 and 20ºC and decreases with increase in temperature above 20ºC. Compared to the influence of temperature, humidity has only a slight effect on sprout growth. Light inhibits sprout growth and it has been shown that red light above 650 nm and blue light below 500 nm both contribute to the inhibition of sprout growth. Potato sprouts grown in the light develop chlorophyll and are shorter and sturdier than those grown in the dark.