Guide to cleaning the fruit off palm seeds

Removing the fruit from palm seeds by the easiest, quickest and most cost effective method

The link to buy Juania australis seeds is here: Buy Juania australis seeds

The fruit would eventually rot away in soil, but the problem is that most palm seeds don’t stay viable for any length of time, it is therefore imperative that the fruit, which is often a germination inhibitor, is cleaned off the seeds in a fast and efficient way, so that the seeds can then be germinated as quickly as possible in the nursery.

In this guide we’re focussing on rare and valuable seeds (Juania australis and Pinanga tashiroi), for which care is required to not damage these very expensive seeds. You should note that seeds of many species of palm are incredibly tough and cannot be crushed even with a hammer, an example would be Acrocomia, Parajubaea or Butia ssp., and fruits of these can be easily placed in a bag then trampled under foot until the fruit comes away from the seed, well, the Acrocomia would need a bit more work than that! Nevertheless so many species don’t produce such indestructible seeds, and here we show you how to remove the fruit without damaging these more delicate seeds.

The first step is to try to harvest the seeds when they are fully ripe, picking only the ripe ones and leaving the rest. If you have time at hand, then placing a suspended sheet under the infructescence (bunch of fruit) and waiting for the ripe fruits to fall into the sheet would be the best method. But, in reality we seldom ever have the luxury of time and collection is usually done quickly. In this instance it is far better to cut the whole infructescence and allow the unripe fruits to finish ripenning while still on the infructescence.

Fig. 1. Pinanga tashiroi fruits

Fig. 1. Pinanga tashiroi infructescences, the yellow infructescence with the black fruits is fully ripe, the green infructescence with the red fruits is not yet ripe

The unripe Pinanga tashiroi infructescence (fig 1) was left together with the fully ripe one for 3 days in a warm room, during which time the ethylene gases produced from the fully ripe fruit goes to speed up the ripening process of the unripe fruit. At the same time the unripe fruit draws the remaining water and nutrition out of the green infructescence, had the red fruits been picked off separate then they would have dried out and not gained that remnant nutrition that they needed. All of these fruits went on to fully ripen and the germination test was 100%.

Fig. 2. Juania australis fruits

Fig. 2. Juania australis fruits.

Fig. 3. Scarified Juania australis fruit

Fig. 3. A scarified Juania australis fruit. A sharp knife is used to slice away some of the outer layers of skin and fruit to allow oxygen and water into the fruit.

Fruits of Juania australis (fig 2) have a waxy coating over the skin of the fruit impeding water penetration of the fruit. This also acts as a barrier to oxygen, and therefore slows the oxygenation and decomposition of the fruit by the natural enzymes (pectins) in the fruit. When fruit decomposes it is an effect of oxygenation of the natural enzymes in the fruit to digest it, so when it’s eaten, the animal extracts those nutrients of the fruit, or the fruit decomposes. The skin is the natural barrier to slow this process. We therefore need to damage that skin of the fruit, by bruising or cutting in a process called scarification. Juania australis is the most sought-after cool-tolerant palm species in the world and its seeds are therefore amongst the most expensive seeds in the world. We don’t just knock them about to try to damage the skin, we take great care to not damage the seeds contained. I’ve used a sharp knife to cut away slices of skin and fruit (fig 3) taking care not to cut too deeply and avoiding the seed contained. Once scarified the fruits are left in a warm room for several hours to oxygenate, this starts the decomposition process of the fruit.

The next step requires soaking the fruit in warm (not boiling) water. Some fruit has naturally high levels of pectin enzyme, and therefore decomposes faster. The Pinanga tashiroi seeds were cleaned of fruit within one day after scarification. This was easily done by rubbing the pre-soaked seeds between my hands, then rinsing the cleaned seeds in fresh water, and allowing to become touch-dry in the air. Juania australis fruits are naturally poor in pectin enzyme and therefore require several days soaking and fermenting to remove the fruit. I add additional pectin enzyme to the water, which you can usually buy in a wine-making shop as a white, crystalline powder. One tablespoon full will usually suffice. Normally, when soaking seeds to hydrate them before planting I would say that the water needs to be changed every day. This is because it stagnates (de-oxygenates) and drowns the emerging embryo in the seed. Seeds need oxygen for respiration during germination. Fermenting fruit is different, we don’t change the water, otherwise we would be throwing our pectin enzyme away and slowing the rate of decomposition. The seed, for the most part is protected from the water by the surrounding fruit, and as soon as the fruit falls away we remove, wash, and dry (to touch-dry) the seeds. The cleaned Juania australis seeds (fig 4) should never be allowed to fully dry out.

Fig. 4. Juania australis seeds

Fig. 4. Juania australis seeds, cleaned of fruit, not allowed to dry-out more than simply touch-dry, and they are now ready for germinating.

Does nicking seeds speed up germination?

This was originally submitted as a question on our old Trebrown forum.

“I was wondering if nicking seeds helps speed up germination on bananas and palms, specifically Jelly Palm seeds? What I mean by nicking is that you cut, scrape or grind away a small piece of the outer seed shell/husk so moisture can quickly enter the seed. I do this on some of my tropical water lilies and lotus and it works great. Thanks, Mike.”

The process is called scarification, where the outer seed coat is scratched to better improve water permeation to reach the Endosperm (seed). It can be done, and many people will swear by it as speeding up germination. We here germinate hundreds of thousands of seeds every year and we NEVER do this. If you attempt this you must be very careful not to go too far and break through and damage the seed. This is the best way to rot your seeds. Of-course the seed needs water to germinate, and many hard coated seeds, if they are very dry or oily will reduce that flow of water. I know from experience that the best way to hydrate seeds is to soak them for longer. Up to a couple of weeks if necessary, but usually 3 days will suffice. Warm to hot water is better. However, make sure you change the water daily or you’ll deplete the required oxygen from reaching the seed, and fungus could also attack the seed. Seeds have hard seed coats to protect the seeds. It’s natural, and seeds will germinate with their coats on. Perhaps one exception could be used if you are persistently trying to germinate as many Jubaea chilensis or Butia species as you possibly can. This process cannot be used for all Butia species, just the fatter seeds. That is, if you’ve tried to germinate a batch of seeds and there are a few remnants after trying for a whole year, then you can try completely removing the whole shell. To do this you would need to crack open the shell in a vice and carefully remove the soft seed without damaging it. It will be obvious to you if the seed is still good or not. The good seeds must then be dipped in a fungicide and germinated in sterile conditions. These will either germinate within a month or die. So always leave this method as the last option. There are many methods used for germinating different kinds of seeds. The oily seed requirement is an important one, which requires frequent washing and leaving seeds in the sunshine to heat-up and dissipate the oil, a process developed for pre-treating Oil palm seeds (Elaeis). There are too many methods for me to list in this thread. I’ll leave those for specific species questions. But I will answer your questions here Mike. Bananas – always soak for a few days. Adding a teaspoon full of potassium nitrate to the water will soften the shell. Always plant the seeds in a regular seed mix. Don’t try the baggie method. 30°C. Keep the soil moist, and the plants humid. Jelly Palm – Butia capitata (I mentioned it above) Soak the seeds for up to 2 weeks if necessary. Adding a teaspoon full of potassium nitrate to the water will soften the shell. Germinate in sealed plastic boxes in a simple medium like Perlite, Vermiculite, Coir or Peat, where the seeds lie on the surface or half buried in the medium. There must be an inch of air space at the top of the tub. And the temperature must fluctuate between about 5°C – 35°C (40°F – 100°F). Seeds will take a month or 2 to start germinating. The ungerminated seeds can then be soaked again, and tried again.

“Thank you Phil for the quick reply. Wow that was a great explanation. It made a lot of sense. I was already soaking the Jelly Palms but will continue for another week with regular water changes. Where do you get potassium nitrate from? Mike.”

Potassium nitrate is the saltpetre, or saltpeter (American spelling) used in gunpowder manufacture. Chemical formula KNO3. I don’t know where you are in the world Mike, but you can no longer buy this off the chemist’s shelves here in the UK. It used to be easy to get, but I guess these days they’ve found alternative remedies for the ailments it was used to treat, and it’s a banned product for obvious reasons. Ironically, those who want to buy it to make explosives can still do so in the large quantities they need direct from the wholesale suppliers in the USA. That is your problem! You would need to buy it in massive quantities, which is not practical for the average seed grower. It really isn’t necessary to use this though. Just soak your seeds for longer if necessary. Seeds from Butia, Jubaea and the rest of that family respond well to temperature fluctuations. Whenever, you need to re-soak your remnant seeds try putting them in a glass jar of water and leave it in the hot sun in a glasshouse all day. That method of soaking really makes them jump.

“Well all this info came at the perfect time. I have Butia x Jubaea seed that arrived today. Cheers, Las Palmas Norte.”