Good & Bad Effects of Ethylene

Ethylene on the other hand, (at room temperature) is a colourless, odourless gas that at (roughly) a concentration of 6% with air, is highly explosive. It freezes at -169.4 C and boils at 103.9 C so is normally found to be a gas unless compressed.

Good and Bad Effects of Ethylene

First I need to point out that Ethylene is different to Ethanol (the full name is Ethyl Alcohol) It is Ethanol that is the Alcohol part of Alcoholic drinks.

Ethylene on the other hand, (at room temperature) is a colourless, odourless gas that at (roughly) a concentration of 6% with air, is highly explosive.  It freezes at -169.4 C and boils at 103.9 C so is normally found to be a gas unless compressed.

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The NORMAL action of Ethylene is to accelerate the normal process of fruit maturation and senescence of fruit and to cause leaves to break off in autumn from deciduous plants.  The ethylene is produced naturally in small quantities by a lot of plants but some plants are more sensitive to it than others – eg Tomatoes, bananas , pears citrus, pineapples, persimmons, apples, melons, mangoes, avocados, pawpaw, and jujubes are very sensitive to it.

It is used to ripen these fruits when they are mature but not ripe.

Fruit is picked mature (therefore hard); transported to a central wholesale market; sold to the local fruit retailer; then taken home to be eaten by the retail customer.

The green, hard, but mature fruit is less likely to be damaged when picked in this condition.

 

But if it is damaged then the injured fruit will produce Ethylene and accelerate the ripening of all the fruit near it.

This is a really good reason to handle all green fruit carefully as the damage is not seen when it is green

but will show up rapidly as it ripens and changes colour – eg Bananas.

Fruit and vegetables picked where they are grown (which is usually a long distance from where they are eaten) and kept for prolonged periods of time, means a consumer can have most fruit and vegetables available to them most times of the year.

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Apples kept in store in reduced oxygen conditions keep well, but as soon as they are exposed to normal air, (i.e. when taken out of the storage conditions), they rapidly ripen and go soft and “flowery” so need to be eaten soon after removal.

Some fruit are quite resistant to Ethylene having almost no effect on them.  Eg: cherries and Blue berries

Ethylene naturally causes a fruit to change in texture, softening, colour (eg a Tomato goes from green to red), loss of chlorophyll (eg autumn leaves) and stem shortening (dwarfing of Poinsettia pot plants).  It is produced by plants when they are injured either mechanically or by disease because, to the plant, damage is still damage.

The effect of ethylene can be used if you want to ripen some bananas by putting the bananas in a brown paper bag with an apple, especially one that is fully ripe or injured so it produces a lot of Ethylene.

 

Some of the BAD effects of Ethylene are to cause vegetables to go yellow, bud damage in dormant nursery stock, drop off of leaves in ornamentals and rapid death of most cut flowers. This is why I would NEVER buy flowers from a Petrol station as their life would be at least reduced by two thirds due to the ethylene from car exhausts.

To reduce the effect of ethylene there are some chemicals that block ethylene production – eg Silver thiosulfate used in cut flower water to increase their vase life. Another “prevention” would be to NOT damage the fruit or flower – ie handle them carefully. I cringe when I see people swinging cut flowers as they walk as that just reduces their vase life by damaging them and so producing extra Ethylene and shortening their vase life.

Ethylene is used commercially as the base of detergents, plasterers, synthetic lubricants and additives so is in great demand world- wide in its own right as a base chemical. It is also used to make polystyrene for packaging and insulation as well as styrene butadiene rubber for tyres and footwear. Anti- freeze and some plastic are also made from ethylene as a base.

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Today’s Did You Know…?

In the first world war there was a great petrol shortage in Australia as it was being used by the army, so private car users needed a petrol substitute and used carbide producers attached to the back of their car.  The carbide plus water produced Ethylene (as is said above) that is explosive but within a modified car engine made the engine work so the driver was able to drive to where they wanted to go.   It was not an efficient system so when petrol became available again people went back to petrol.

Carbide can also make pineapples flower all at the same time but it doesn’t produce very good fruit.

Bacterial Infections

In last months blog we referred to both good and bad fungi and bacteria being present everywhere in the environment, and many of which cause diseases in plants while others help plants, animals and humans.For instance – Penicillin (extracted from the fungi Penicillin)
could be called ‘Good Bacteria’ because it can be used in medicine to treat diseases.

Bacterial Infections

In last months blog we referred to both good and bad fungi and bacteria being present everywhere in the environment, and many of which cause diseases in plants while others help plants, animals and humans.

For instance – Penicillin (extracted from the fungi Penicillin)
could be called ‘Good Bacteria’ because it can be used in medicine to treat diseases.

courtesy of http://findersfree.com

But it could also be called ‘Bad Bacteria’ because it will decay your food rendering it inedible if it manages to get a foothold in a damaged or overripe piece of fruit (eg a lemon) or a slightly old piece of bread as seen in these pictures.

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Edible mushrooms could be considered ‘Good Fungi‘ but other mushrooms can be ‘Bad Fungi‘ as in the case of “magic mushrooms” or toad stools.

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Rhizobium (discussed in a past blog) are ‘Good Bacteria‘ creating a mutually beneficial arrangement between special Pea family plants and Rhizobia bacterium.

Fungi will grow faster and bigger when the LOCAL micro climate around and underneath the leaves of a plant are shaded.

There might be good light but no direct sun, therefore less evaporation trapping aerial moisture (fungi need moisture to continue growing as they are mainly single cell thick Mycelium – which is the equivalent of root hairs in flowering plants).

As soon as the local micro climate area becomes drier (this may be from a strong breeze, direct sun or a Fungicide) then the fungi will revert to its resting stage of a spore.

When it comes to which fungi or bacteria are going to be beneficial or harmful to your plant it is a case of “first in, gets most of the food”.

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To give your plants a good fighting chance, give them a good BALANCED feed supply via some fertilizer and/or organic matter, so the cells are thicker and the plant can grow stronger. This way that plant will not let the ‘baddies’ in, resisting fungal attack. (resist attack but not totally prevent a disease attack)

The actual balance required in a fertilizer depends on the specific requirements needed for those plants. This could be that those plants require an acid soil (ie. a pH of below 7) such as azaleas & camellias. Or an alkaline soil (ie. a pH of above 7) such as citrus trees.

Most plants find that a pH of 6 to 6.5 gives them the maximum nutrient availability without excess or deficiency of most nutrients.

To treat fungi and bacteria there are some organic fungicides that can be used if you do not want to use a chemical fungicide.  Eg: Sulphur is a good general fungicide BUT do NOT use it on the cucumber family (cucumber, pumpkin, zucchini, etc) as it is toxic to them.   Look on the label as there is a warning on it to not use them on the cucumber family.

Avoidance is another method to reduce fungus attack.   Leave enough space between trees when planting to allow flow through of air, and water below the leaf line via a drip line in the soil if possible.  These two avoidance methods will help air to circulate freely through the plant so the leaves do not stay wet as fungi needs moisture to infect a plant and spread to other plants.

Today’s Did You Know…?

One of the reasons for the “Damping–off” of seedlings is bacterial infection by Pythium, Phytophthora and Rhizoctonia.  In the home garden there is no way to distinguish which bacteria might be the problem without getting the infected plant analysed by your Local Department of Agriculture.

bacteria-infections

The seeds need to be watered with fungicide in order to prevent these bacteria from destroying young growing seeds.

This of course is not worth it for the home gardener as the remedy is much the same.  However if you were farming you would want to know exactly which bacteria was the cause so you could fix the problem with a specific fungicide for that particular variety of Bacteria.

There is no good organic fungicide to reduce these bacteria so a chemical one is needed (eg: Zinib or Mancozeb) if you want to have any chance of propagating your seeds or cuttings.