Growth and Development of Horticultural Crops (1+1)

2. The respiratory climacteric

• Kidd and West (1930) observed that in apple fruits, a major change occurs in respiration rates during their ripening. They found lowering of respiration rate in maturing fruits followed by large increase in respiration during ripening. And after reaching a climacteric peak, the rate of respiration falls.
• The period of occurrence of climacteric peak in fruits show variation in different fruits, e.g. at the time of optimum eating quality as in pear, it slightly precedes this optimum in banana and apple or just before the fruit is fully ripe as in tomatoes. Earlier it was suggested that climacteric is associated with the hydrolysis of food reserves, but it has not been found true in all cases, e.g. orange, lemon, grapes and fig in which case climacteric rise in respiration is not found during fruit ripening. The process of fruit ripening proceeds slowly in these crops. Hence, these fruits are termed as non climacteric fruits.
• As regards occurrence of climacteric, fruits may be divided into two types:
1. Climacteric fruits,
2. Non climacteric fruits,
Climacteric Fruits	Non-climacteric Fruits
Apple	Chillies
Apricot	Orange
Avocado	Lemon
Banana	Mandarins
Sapota	Watermelon
Custard apple	Grapes
Fig	Pineapple
Mango	Strawberry
Melon
Olive
Peach, Pear
Persimmon
Plum
Tomato


In non-climacteric fruits, the rate of respiration remains steady during their ripening.

• Climacteric rise has been found affected by low oxygen and increased concentration of carbon dioxide. Both these factors prevent climacteric rise and thus improve storage quality of fruits. Storage of fruits in polythene bags produces nearly the same effect because plastic can lower oxygen and elevate carbon dioxide around fruits.
• In climacteric fruits, the respiratory climacteric initiates after the fruit growth is complete. Gane (1937) established that ethylene stimulates climacteric rise and that ripe banana stimulates it in the same manner as ethylene.
• Some further researches established that there is a marked rise in ethylene formation in fruits either just at or just before the onset of climacteric rise. It has also been found that the ability of ethylene to induce climacteric rise is found in climacteric fruits.