Fruit Ripening and Seed Dispersal the Reality

Fruit Ripening and Seed Dispersal

The reality of a fruit and its seeds is a complicated and fascinating thing. Fruits rely on a variety of factors in order to grow, ripen and finally reproduce. The process of fruit ripening affects not only the taste of a fruit, but also its ability to disperse seeds. Seed dispersal is essential for reproduction of fruit and many components must be present and perfect in order for effective seed dispersal to take place.

To start, it's important to point out that fruits come in a wide variety of shapes, sizes, types and tastes. Some fruits are sweet, some are sour, and some have no specific taste. The taste of any fruit depends largely upon the compounds inherent within it. Most fruits are comprised of a combination of fructose, acids, vitamins, proteins, starches and cellulose. The first two components mentioned, fructose and acid, are the most important aspects affecting the taste of fruit (Vines, 2010). Different fruits contain different proportions of these materials which subsequently affects their taste. In general, fruits containing more fructose than acid taste sweet, while those containing more acid than fructose taste sour. Likewise, fruits containing equal quantities of acid and fructose, like oranges, taste both sweet and sour.

However, other factors can affect the taste of fruits. Typically raw fruits contain more acids but upon ripening become sweeter as sugar levels increase and acid levels decrease (). Fruits that contain large quantities of starch, like bananas, may have a neutral taste when raw, but as the fruit ripens the starch is converted into glucose which makes the fruit taste sweeter (). Moreover, many different varieties of each type of fruit exist which results in two pieces of the same fruit tasting vastly different. Also, variations in climate, growing process, water levels, quality of soil, etc. can change the proportion of materials within the fruit causing two pieces of fruit of the same variety to possess different tastes (Vines, 2010).

The ripening process of fruits palpably affects taste, but alters more than just taste. As fruit ripens, the process by which its seeds are dispersed changes. Many fruits rely on wind, water, gravity and even animal fur to disperse their seeds. However, many fruits rely on the terminal stage of their ripening to expel and consequently spread seeds. Some seed pods within fruits burst open when fully ripe. In some cases, this bursting literally flings the fruits' seeds in all directions or into the wind which then spreads them. Also, many fruits require full ripeness in order to disperse completely mature seeds (Yamaki, 1995). If seeds are released before maturation is complete, seeds may not be able to grow into an effective plant that can reproduce.

Other fruits that lack this violent expulsion rely on their ripened forms to tempt organims to consume their tissues and late disperse the associated seed (Yamaki, 1995). Animals and humans that eat these fruits cannot digest their seeds. Thus, after they have consumed the fruit's tissue, they will later release the seeds during excretion. As the digestion process takes time, it's likely that excretion will take place far from the fruit's original source.

In addition to aiding dispersal, seeds rely on their fruity tissues in order to metabolize. It is a common misconception that fruit seeds rely solely on the fruit's fructose for metabolism. While fructose is the only component of the fruit that is able to directly metabolize, the other materials present are essential to the seed's metabolism. While starch is a polysaccharide molecule, it is unable to metabolize in its complex form. The starch molecule must be hydrolysed, or digested, into a simpler form in order to be metabolized. Thus, this polysaccharide is digested into fructose, which is a monosaccharide that contains the components necessary for metabolism (Vines, 2010).