Rambutan tree reaching its genetic potential

I posted about two rambutan trees 3 weeks ago, saying how one of them (let me call it tree A) had been much weakened by thoughtless human activities, while the other one (tree B), pretty much on its own, had been growing healthily.

Tree B was so fully laden with fruits these two weeks that some of its lower branches and fruits were almost touching the ground. Two days ago (25 Jan 2019), a team of volunteers harvested over 100kg of rambutans from this tree alone, using different tools and methods. One of them, with his inborn agility, even climbed to the high branches.

Can you spot the young man high up on the tree?

I tested the fruits from tree B with a refractometer. The brix value was 24 and the fruits were really sweet! (Please scroll towards the end of this article for the meaning of Brix.)

There is also a rambutan tree (tree C) some 80m away from tree B. I tested its fruits too. The value was 22, slightly less sweet than those of tree B. Of course, there was no fruits from tree A, which had lost almost all its leaves. I remember fruits from both trees A and C were sweeter than tree B in the past. Now tree B has become the most prolific and its fruits are the sweetest. I believe it has probably performed to its full genetic potential and it is interesting to know why. Let me summarize my thinking below.

There are a few mature rambutan trees growing in the area. They were probably planted by people a few decades ago. Over the years, nobody really took care of them. They had been growing on their own. Due to the natural surroundings, the trees had been doing quite well, producing fruits for people and animals to enjoy during rambutan season every year for many years.

Tree A is remembered as the tree giving high quality fruits both in terms of sweetness and texture. The soil around the tree was rich dark soil permanently and naturally mulched with fallen leaves and living plants (grass and weeds). One and a half years ago, for some reason, some people surrounded this tree with concrete and the remaining soil is covered with a large amount of sand.

Tree A has lost most of its leaves

Tree A is surrounded by concrete, with remaining soil covered by large amount of sand.
This is cruelty to the tree!!!

The soil now is mostly dead, not being able to support soil creatures and nutrients cycles are practically nonexistent. The tree has lost most of its leaves. It has turned from a majestic tree to such a pathetically small and weak tree in just one and a half years. The tree is still alive, but only just. It is between life and death. Sometimes we see new growth on some branches, but soon it withers.

Tree B, in the past, produced fruits not appealing to most people, not sweet (a little sour actually) and the flesh was watery, soft and stick to the seed. Three years ago we started using the plot just next to this tree for natural farming. To improve the poor soil, we have been adding a lot of organic matter and keeping the soil heavily mulched with dry leaves, branches and living plants (crops, grass and weeds). We created two large compost piles under the shade of tree B and regularly add kitchen waste, farm waste, etc. to them. The soil has been improving gradually and steadily. The compost piles are doing especially well. Probably there is a symbiotic relationship between the piles and the tree. A compost pile is a living system and the tree is another, each benefiting from the presence of the other. I also pick up all human rubbish, plastics, discarded tools, etc. that I can see left on or in the soil, as all these can negatively impact the health of the soil.

With this kind of thoughtfulness and a little effort, I think I have helped tree B almost reach its full genetic potential. Tree B is now one healthy tree, not only producing a lot of very sweet fruits on the branches and good amounts of rich exudates in the roots, but also sequestering large amount of carbon, creating a lot of humus in the soil, benefiting creatures both above and below the ground.

After more than 100 kg of fruits have been harvested, Tree B still has so many fruits.

Although very sweet (24 Brix) , the fruits of tree B still have undesirable texture: too soft, too watery and sticking to the seeds. I believe these traits are due to genetics.

Tree C is on the far end of the farm and is pretty much on it own. The fruits of this tree is sweet (22 Brix), and have nice texture. However, I am concerned that this tree may get more and more human disturbance soon. Already, the human-constructed landscape is getting too near to the tree.

Human-constructed landscape getting near to the trees, including tree C.

Threats to the natural environment
Tree B has benefited from the natural environment enhanced and sustained by our care and effort. However, things happening in the area are threatening what we have created: people come and dig away the good soil and compost materials from near tree B, people apply chemical fertilizers and create bare soil for growing their crops nearby, expansion of constructed landscape which requires regular and noisy mowing and destroys biodiversity.

We need to help people understand the importance of respecting and protecting nature because human life, as well as all other living things, depends on it.

Sign put up to ask people not to disturb the compost pile

Some people still grow crops with bare soil 

Lawn requires regular mowing and is not conducive to wildlife

Thoughtless human activities are killing soil

About Brix value

Brix value, measured with a refractometer, is an indication of the sum of sucrose, fructose, vitamins, minerals, amino acids, proteins, hormones, and other solids in plant juice or sap. It is often used to indicate the nutrient density of fruits and vegetables.

The four fruit samples from two trees I tested had brix values ranging from 22 to 24. These are very high values, indicating that the two rambutan trees are very healthy and produce nutrient-dense fruits.

For comparison, we can look at the following:

In 2017, in a Universiti Kebangsaan Malaysia study to investigate the physicochemical properties of rambutan, eleven cultivars of ripe rambutan fruits obtained from the University Agricultural Park were tested. The Brix values range from 13.78-16.67 °Brix. (Source: http://www.ukm.my/jsm/pdf_files/SM-PDF-47-7-2018/16%20Kong%20Fei%20Chai.pdf)

Alquimia Fruits is an international fruit producer and exporter. In their website, there is an article titled CHINA: “THE BEST RAMBUTAN COMES FROM BAOTING”, in which they say: “Our rambutan cultivation area can not be compared to that of the Southeast Asian countries, but our quality is better. Our rambutan is not only juicier but also tastier, and can reach up to 23 Brix. Baoting rambutan received a trademark certificate as proof that it is a national regional product. ” (Source: https://alquimiafruits.com/en/2016/11/09/china-el-mejor-rambutan-viene-de-baoting/?fbclid=IwAR3lXvSxIZoe39uU80ryXHC_mRM5O4mtTUx36wXs7UDQu1HnC8Tr2tlLWnQ)