Climacteric (botany)
In plants, climacteric is a process that is initiated by a two to three-fold increase in respiration ( oxygen uptake and carbon dioxide release). Biochemical changes take place in fruits, such as B. the breakdown of cell wall pectins and the hydrolysis of starch. This has a senescent (age-inducing) effect on the fruit. The gaseous phytohormone ethene has an auto-catalyzing effect . Ethene is thus absorbed, which stimulates the internal cell synthesis of ethene. The gas is then released and can again have a stimulating effect on other fruits and thereby exert the senescence effects.
Post-maturity
Whether fruits can ripen after harvest depends on the one hand on the time of harvest and on the other hand on their respiratory behavior, i.e. the oxygen uptake and the release of carbon dioxide. Fruits whose carbon dioxide release increases after the start of their ripening process and which therefore have climacteric fruits are accordingly called climacteric fruits : They continue to ripen after the harvest, while fruits that do not are called non-climacteric fruits . In order to continue to ripen after the harvest, climacteric fruits must also have reached a certain minimum ripeness , i.e. a certain stage of carbon dioxide release, which is called picking maturity or harvest window . During the subsequent storage , these fruits continue to develop until they are ready for consumption .
Post-ripening depends, among other things, on the autocatalytic phytohormone ethylene (chemically correct ethene ). Therefore u. a. Bananas should not be stored together with tomatoes. The particularly high ethylene release of the tomato allows the banana to ripen faster. The same goes for storing fruits and vegetables in a room, as this substance has a perishable effect on most vegetables. The small difference in density between ethene (1.2611 kg / m³) and air (1.293 kg / m³ at 0 ° C and 1013.25 hPa) has in practice no effect on the storage of non-climatic fruit and vegetables. It is therefore almost irrelevant whether nichtklimakterische fruits and vegetables are stored below fruit or not, also bearing fruit with dessert fruit .
Examples of climacteric and non-climacteric fruits
- Menopausal fruits: apples , apricots , avocados , bananas , pears , figs , kiwis , mangos , papayas , passion fruits , peaches , plums , tomatoes
- Non-climatic fruits: pineapples , blueberries , strawberries , cucumbers , limes , oranges , satsuma mandarins , table grapes , lemons
literature
- Hans Mohr (founder); Peter Schopfer , Axel Brennicke : Plant Physiology. 7th edition. Spectrum, Heidelberg 2010, ISBN 978-3-8274-2351-1 .
Individual evidence
- ↑ a b Container Handbook. Chapter 15: Maintaining the quality of perishable goods, Section 15.2.3.4; Allelopathy.