Post harvest Management of Horticultural Crops (2+1)

Physiology of fruits and vegetables

Fruits and vegetables are alive after harvest
Horticultural Produce respire by taking up O2, giving off CO2 and heat and also transpire. While attached to plants, losses due to transpiration and respiration are replaced by flow of sap, which contain water, photosynthates and minerals. These functions continue even after harvest, and since the produce is now removed from the its normal source of H2O, photosynthates and minerals, the produce entirely depend on their own food reserves and moisture content. Therefore, losses of repairable substrates and moisture are not made up and deterioration has commenced hence, produce are perishable.

Physiology of Fruits and Vegetables
Fruits and Vegetables are living entities and diverse in structure, composition and physiology. They have the typical plant cell system.
The life of fruit and vegetables can be conveniently divided into three major physiological stages following germination.
These are: Growth Maturation Senescence

• Growth - involves cell division and subsequent cell enlargement, which accounts for the final size of the produce.
• Maturation - usually commences before growth ceases and includes different activities in different commodities. Growth and maturation are often collectively referred to as the development phase.
• Senescence - is defined as the period when synthetic (anabolic) biochemical process gives way to degradative (catabolic) process, leading to ageing and finally death of the tissue.
• Ripening - is a phase of qualitative change which occurs in fruits particularly, after completion of maturation, during which the fruit becomes acceptable for consumption in terms of taste and flavour. Ripening occur during the later stages of maturation and is the first stage of senescence.

Normally development and maturation processes are completed before harvest. The completion of this stage is referred to as ‘maturity’. But depending upon the nature of produce and the desired characteristics in a particular fruit or vegetable, the stage of maturity differs. Sometimes in fruits like mango, it has to attain the full stage of maturation to develop the characteristic flavour and taste, while in vegetables like Okra/beans/drumstick it should not mature fully where it becomes fibrous and unpalatable. Similar terminology may be applied to the vegetables, ornamental and flowers, except that ripening stages does not occur. As consequence it is very difficult to delineate the changes from maturation to senescence in vegetables and ornamentals. Vegetables are harvested over a wide range of physiological ages, that is, from a time well before the commencement of maturation through to the commencement of senescence.Based on this requirement terms like ‘physiological maturity’ and ‘harvest maturity’ are used.