Updated: Sep 5, 2021
This blog is the original translation of the article in order to attract the attention of a wide audience of stakeholders to the processes of robotization in agriculture.
"The date is an extremely interesting and noteworthy plant. I will try, to the best of my modest strength, to give a description of the annual cycle of work on caring for the tree, as well as interesting data about this wonderful palm tree.
Let's start with what is happening on the palm plantation these days. Everything that will be presented here applies only to the southern Arava and the varieties grown here. And even then, in each farm business is conducted differently.
On these days the thorn removal cycle ends. On the cutting of a palm branch, reaching 3 meters (or more) in length, the leaves close to the trunk are underdeveloped and are sharp and long thorns. The spikes will interfere with further work and are therefore removed at the beginning of the season. The photo shows the sepal of the future inflorescence. Soon it will be necessary to work on it and the thorns, if not removed, will interfere.
These spikes are tough and extremely sharp! There are rumors about the poison allegedly located on the thorns. The wounds are indeed painful, but the reason for this may be infection from dirt on the thorns or from a broken end remaining in the depth of the wound.
The work is carried out at the crown level and consists in removing the thorns with a heavy knife. The work is simple, but requires a certain skill and a lot of patience - there are many hundreds of trees. Three people work on the tractor, in our case there is one student, in an 8 - hour working day they manage to process about 40 trees. After finishing work, we move on to the next palm tree. Pay attention to the tractor - the machine deserves a separate story.
1. That is, if we can develop a robotic system that will do all the work in the field of thorns, then the process of removing thorns can be excluded from the total amount of work.
In this case, instead of three employees, it is quite possible to get by with the work of one remote operator who will oversee and control the entire process.
In our case, we are working on a plantation of dates of the Dekel Nur variety (دڤلة النور - deglet Nur in Arabic). It can be translated as the date of light, although NUR in Arabic is not just light, but a flame, a strong fire. The "correct" fruit of this breed shines through, and even a bone is visible inside. Dekel Nur is preferred by many date growers to all other varieties. The taste is not very sweet, with a special aroma and taste. But today the market is looking for the Majul-Majul variety, large and fleshy fruits.
After removing the thorns, you can start collecting the inflorescences to extract the pollen. But first, a few words about the reproduction of the date palm.
2. As we previously determined, there is no need for a thorns removal procedure, which allows us to immediately start the process start collecting the inflorescences to extract the pollen.
Palm is a dioecious and heterosexual plant, that is, male and female flowers are on different trees (houses). From an evolutionary point of view, this is the best way to avoid self-pollination and thus achieve better offspring, avoiding intrafamilial relationships. Genes are exchanged and the integrity of the species is preserved. There are rudiments on the date flowers, indicating that they were previously bisexual.
In the cultivation of dates, success will be achieved when a person helps to transfer pollen from male flowers to female flowers. Only then can full-fledged fruits develop in sufficient quantities. In nature, pollen is carried by the wind. The pollen leaves the plant when it contains about 50% water and loses moisture during flight. Falling on the wet pistil of a female flower, the fruit sprouts and sets.
The date is little adapted to wind pollination - the pollen is not very light, and the pistil is small. Thus, the transfer of pollen by the wind and getting it onto the pistil is difficult. But from a botanical point of view, the date plant is successful, grows over large areas and reproduces successfully, including by shoots.
There is evidence that 3000 years ago, man understood the need for pollination and did it by bringing the inflorescences of male flowers to the female ones. But only in the 20th century did we learn to collect and store pollen. Date pollen is a product that many people are engaged in, it has a price and demand. Methods for checking the quality of pollen have been developed and the buyer knows what he is buying and what result to expect.
Thus, it is possible to carry out pollination work during a whole working day, not to depend on the time of flowering and the readiness of pollen and the readiness for pollination of female flowers.
Date pollen can cause allergies. You can't get used to it. In this case, it is recommended to move away from the plantation during flowering. Over the years, the percentage of the population suffering from allergies increases.
3. In the case of remote control, the operator is not in danger of any allergies
The amount of pollen from a tree grows with age and reaches a maximum by the age of 20-30 and can reach a kilogram or more. 1 liter of pollen weighs 600 grams, in a gram there are a billion (approximately) pollen balls, one inflorescence produces 30-60 billion, and a flower produces 1.5 million. For pollination from the air, 70 billion are used per dunam and per 1 sq. mm. 70 grains fall. After the boring statistics, let's see how the inflorescences are collected.
The inflorescence is tied so that the pollen does not scatter. Each one separately. Inflorescences do not appear at the same time, so each tree must be approached 2-3 times. The opened inflorescences are carefully removed so that the pollen does not scatter, and are folded into a bucket.
Pay attention - the thorns on the branch blocked access to the inflorescence. It looks like a male inflorescence of a date palm tree in close-up.
4. For surveillance, you can use a drone, which will be equipped with a wide-angle video camera. This solution should allow real-time video filming with video broadcast to the operator's central station. In addition, this data must also be supplemented with topological coordinates in the form of points of interest.
5. The process of wrapping mature inflorescences should be entrusted to a multifunctional manipulator with a set of interchangeable nozzles for specific tasks. Such a manipulator must be installed on a mobile platform.
After removing the thorns and collecting pollen from the male trees, it was time for pollination.
Before pollination, it is necessary to collect the inflorescences and transfer them to a closed room, preferably 2-3 hours in advance. The pollen taken from the tree has a "germination" of about 80-90%, and a moisture content of about 50-60%. As long as there is moisture, pollen can quickly deteriorate, it is necessary to dry it quickly and thus maintain the ability to fertilize. In nature, pollen immediately begins its journey in search of female inflorescences, and therefore has almost no time to deteriorate.
Next - we hang it for drying in a closed room.
Inflorescences with already opening flowers are folded into buckets so as not to lose pollen.
The room should be dry and warm in order to quickly dehydrate the pollen, but not spoil it by overheating. If the flowers do not open during this time, obviously the pollen in them has deteriorated. This is usually caused by the genetics of the plant. Palm trees that do not meet this condition are removed.
Pollen production. The mechanical pollen separator has two functions - the release of pollen from the opened flowers and its sifting. In hot and dry climates, the pollen is ready to be consumed when it leaves the device. This is how it looks:
In the picture we see a machine that looks like a dryer for home clothes and works on the same principle, then a cyclone hood for collecting pollen, and below under the cone is a box for collecting pollen. After that, the pollen is transferred into a bucket, the machine is freed from the used inflorescences and is ready to continue working. This is what pollen looks like when it comes out of a car. Not visible in the picture, but there are remnants of inflorescences that will need to be removed.
Drying the pollen. As a rule, the pollen is not dry enough when it leaves the car. Dryness of pollen is determined by touching it with your hands. Dry pollen pours through your fingers very quickly, almost like water spills. Wet, rolls into lumps, leaves a feeling of coolness on the finger. Of course, sometimes we need to send pollen to the laboratory for testing, to make sure that everything is in order and our feelings do not deceive us.
To dry, the pollen is scattered in a thin layer on absorbent paper and dried. The dry pollen is sieved again, as seen in the photo.
Pollen storage. Not all of the collected pollen is immediately used. You can store pollen in the freezer until next season. It will certainly lose its qualities, but about 50% of germination is considered acceptable. Dry, in theory, you can simply store it in a closet on a shelf, but it's better not to risk it. In North Africa, Majul pollen has long been stored in caves. But this variety is not particularly picky about pollen quality.
This refrigerator stores pollen at minus 18 degrees. Each box has a plastic cup with holes. There is CaCl2 in the glass. This substance is not stable and tends to attach 2 water molecules and thus keep the pollen dry.
The last thing left is to cook the pollen and spray it. First of all, the pollen is mixed with talcum powder to increase the volume and weaken the action. A small amount of coal dust is also added to make the mixture "flowable". In a bucket, this mixture behaves like a liquid. This is what a mixing machine looks like.
The volume needs to be increased, because each tree needs about 6 grams of pollen and the larger the volume, the easier it is to control the process. Less pollen concentration, fertilizes fewer flowers and produces fewer but larger fruits. So, we kill two flies with one blow.
4. From the point of view of automating the entire cycle of pollen preparation until the moment of pollination, it is not very difficult. All we need is the development of mechanics and the organization of the collection of telemetries data.
Pollination in our case is mechanical, the fan is able to raise the pollen up to 20 meters in height, directing its flow to the crown of the palm tree.
5. The pollination procedure, like all previous processes, is entrusted to a multifunctional manipulator with remote control. The platform is equipped with a system for determining the direction of the wind, while constant remote control of its direction is carried out.
This picture shows already opened inflorescences and still closed ones. So, pollinating has to be done in several passes. By the way, it used to be customary to plant male trees in a line, from the side of the wind. Wind in nature performs the function of pollination. In a ratio of about 1 to 20. The photo shows a line of such trees, in our case from the north side, because the winds in the Arava blow mainly from the north. Today, heterosexual trees are planted separately. So, 2 years ago, 2,400 female trees were planted simultaneously on a separate plantation, without a single male tree.
Man has been growing dates for about 6,000 years. The peculiarity of the date palm fruit is in a large percentage of sugars, on one tree there can be about 100 kg of sugar (in fruits). Obviously, according to this indicator, the date palm is in first place in the world of plants. The date is not only a supplier of energy, but also carbohydrates. In practice, in ancient times, people who lived in the desert were completely dependent on this fruit.
The peculiarity of the date in a long ripening period, up to 200 days, is that the fruit, after ripening, remains on the tree and dries up on it, thus achieving better preservation. Another feature is that the fetus grows at its base, as if pushing the finished cells up and building new ones from the bottom up.
Date palm fruit, regardless of cultivar, will never reach its full potential unless the number of ovaries is reduced, usually during pollination. The maximum size of the fruit will be obtained if only a tenth of the flowers or ovaries are left, and this is taking into account the 50% success in pollination. So, all the resources supplied by the palm tree to the fruits will go to a smaller number of fruits, but in a larger amount. Naturally, this rule works up to a certain limit, and the fetus cannot grow indefinitely. The bottleneck, in the truest sense of the word, is the branches and petioles.
To do this work, you need to climb up again to the crown of the tree.
The more flowers there are in the inflorescence, the larger the cross-section of the stem and, therefore, the more resources the tree can bear fruit. Therefore, thinning depends on the size of the inflorescence. More ovaries can be left on a larger inflorescence.
The date fruit grows at night when the tree does not evaporate water and there is sufficient turgor pressure. Therefore, the amount of water and minerals that the tree receives during the ripening period is critical for the successful development of the fruit.
Thinning can occur in several ways - by reducing the percentage of fertilization of flowers, by reducing the number of petioles with flowers, or by thinning the flowers on the petiole. It is customary to work in two ways - by reducing the number of petioles and / or by decreasing the percentage of pollen germination. The latter is used mainly for the majul variety and is the cheapest, although not accurate, way to reduce the number of fruits. In practice, these two methods are combined.
As a rule, with mechanical thinning, some of the petioles are removed, and the rest are shortened in length.
The use of weakened pollen is the cheapest way to reduce the number of fruits, but also the most imprecise and poorly predictable. There have been attempts to irradiate the pollen, thereby weakening its germination, and to spray it from an aircraft. In theory, no other thinning work was supposed to be carried out - the required number of ovaries should have remained on the inflorescences. The problem with this method is the relationship between the pollination dose and the percentage of usable pollen. In practice, it is impossible to obtain consistent results and, in turn, to calculate the pollination parameters. And using an airplane is not cheap, especially when you consider that not all flowers open at the same time and the process can take a long time.
In theory, thinning can be carried out until the fruit is about 1 cm in size. Thus, there is relatively little time left to get the job done. Thinning is the most responsible and laborious process for the entire period of fruit ripening. There is a lot of research and positive results on how to do this work, but nevertheless adjustments are made on each plantation and the work is also based on experience.
Let's see how this actually happens.
In the picture above, we can see the removal of the hard shell covering the inflorescence. We already know that in Hebrew it is called מתחל, Ashkenazi Jews must emphasize the last syllable - matНal. Please don't be confused!
Now we cut off the inflorescence in its middle. Thus, we reduce the length of the supply "pipes" to the fruit.
On the upper tier of inflorescences, leave 60 petioles and 20 fruits on each.
As you can see, on each inflorescence, you need to accurately count the required number of petioles.
After that, we count 20 flowers on one and trim the inflorescence according to its length. Let's hope that on average everything is correct. On the lower tier, we leave about 10-12 flowers and 40 petioles.
Fruits gain more weight during ripening than nature calculated when creating a palm tree. Therefore, the petiole is tied with a rope to a neighboring branch so that the weight falls on it too. In this case, the petiole is bent so that the bunch hangs down. The picture shows what the tree looks like after this procedure.
This position of the bunch facilitates the subsequent covering with mesh bags. What it is for, we will tell later.
In the meantime, let's see how the tie is performed.
We bend the petiole with a bunch down, fixing it in this position, tie it with a rope to a neighboring branch. It seems easy and simple, but in fact it is one of the most difficult jobs on the plantation. The branch is very stiff and requires a lot of effort to bend and hold. Plus add summer warming, because after 9 am the sun was already beating down. You need to bend it with force, but carefully, otherwise it will not keep itself waiting long and break.
The next photo shows an orange thread tied with a tourniquet. We haven't seen her before, when was she tied up and why? During the thinning of the inflorescences, the petioles are tied with an elastic thread so that they are denser and facilitate the work when knitting - the fruits cling less to neighboring branches when bent.
This plantation uses two harvesting technologies: mechanized and manual. For manual, you need to bend the branches and put bags on the bunch. During mechanized harvesting, the petioles with fruits, on the contrary, are raised to the top and, bending to the side, are placed on a neighboring branch for even weight distribution.
During work, there are unfertilized inflorescences, for this there is a secateurs on the belt. All unnecessary is removed.
Another look at a properly tied bunch.
By the way, the girl in the pictures is not an exploited refugee from Africa, but an army reserve officer. After leaving the army and before the traditional journey to the east, I decided to earn some money and just help (this is not the best place to earn money).
Next, we will learn how the Majul fruit is harvested in the southern Arava for a specific starting product. I will try to explain why there are so many reservations.
First, the product. We are talking about a relatively recent fashion on the market - wet majul (מג'ול לח). Instead of the usual 15-20% moisture, the fruits are marketed with 30% moisture. Wet fruit is soft and it is much more difficult to get a quality finished product. It's much easier to work with dry fruits, but you can't argue with the market ... The variety and place also impose restrictions. Therefore, this entry only applies to farms in Yotvata and Samar. And there is a difference between them.
This is what a tree looks like in mid-August. Fruits on one cluster ripen unevenly, depending on different conditions, the difference reaches 3 - 4 weeks. Since we only need fruits of a certain degree of readiness, each tree must be approached 5-6 times, collecting only fruits of the required quality. The technique used here is unique and is only used in the mentioned farms.
The "wings" installed on the lifting platform cover the crown of the palm tree 360 degrees. After that, the tree is gently shaken and the ripe fruits fall between the outer funnel and the inner cone, not a conveyor belt.
Fruits, falling on a stretched tarpaulin and rubberized conveyor, are almost not damaged. After that, the dates are spread in a thin layer over the boxes. The platform is lowered, boxes with fruits are unloaded, we take empty ones instead - and forward, to new labor successes.
This is what the driver's workplace looks like. The tractor is operated from a platform.
This is what a vibrator looks like. It grabs the tree trunk, the upper bracket is lowered, the belts are loosened and the vibrator works without transmitting vibration to the tractor. By the way, you cannot leave the platform near the ground. Curious donkeys immediately go there and eat all the parts covered with rubber, maybe they lack something for metabolism. But today they are in the enclosure, so you can relax.
Due to the heat, work is being carried out at night, from 20.00 to 8.00. After that, only sorting and packing works. But more on that later.
In the morning we also visit other cultivated plantations.
Today weed control on plantations is done with donkeys. Despite the fact that they are donkeys, during the ripening of dates, they realize that picking dates that have fallen from the tree is easier and tastier, and they stop doing their main job. During harvesting, you have to fight weeds by spraying ...
Now let's start our shift at 8 pm. It's already dark and cool enough. But during work it is not easy, I drank about 3 liters of water from 8 to midnight. Otherwise, the body is dehydrated, and not long before the dropper in the emergency room. Although, this is different for everyone.
Looks romantic, I agree. I personally don't like night shifts, but this is the best night job I've ever done. For photography lovers, these are not the best conditions. There is a lot of dust, and if you value your photographic equipment, it should be protected.
During work, dozens of bats revolve around, they eat insects attracted by the light of the searchlight. For them (mice) this is a real harvest festival. At the same time, they fight moths and cicadas, pests on plantations. On the day, mice fly away to "spend the night" in rock crevices in Jordan and to the west, in the Negev mountains.
When zooming in on the picture, dust is visible on the lenses, one disappointment.
We put the finished products here and pick up empty boxes to continue working.
We put the finished products here and pick up empty boxes to continue working.
In conclusion, a few words about the cleaning technology, its pros and cons. Plus - this is a minimum of people, a minimum of physical work, the work is progressing relatively quickly. Minus - about 15% of the crop is lost. Some just fall to the ground to the donkeys, some are damaged during mechanized harvesting. Large investments in equipment, its repair and operation. Why was this method chosen then? Despite the losses, labor costs are lower and justify the cost of the lost crop. Finding, training and supporting a large group of people for a couple of months gathering in these places is not an easy task.
How do they work on other farms? It is customary to cover the bunches with mesh bags. Ripe fruits fall into the bag, 100% effective. But this works well in the case of dry majul, in order to collect the wet one, you need to remove the bag, manually select dates of the desired condition from the bunch, and put the bag back on the bunch. A lot of work, a lot of attention and diligence. Of course, when it is done by Thai people or refugees from Africa, you don’t think about it.
After harvesting the fruits, it was the turn to cut the leaves. First, let's try to understand why they do it. At the same time, we will get a little familiar with the structure of this species, which is widespread in the country.
The leaves hanging and sticking out on the sides of the palm interfere with the mechanized processing of the tree. People working on the platform should have enough room around the palm tree.
This is what a date plantation looks like during operation. But first, let's look at the tree structure.
At the end of each branch is a terminal bud (terminal bud or apical bud). At the end of the bud is the meristem, the maternal tissue responsible for tree growth. The date palm consists of one branch (trunk), at its end there is a bud from which leaves and flowers sprout.
The color of the bud is light cream, soft and firm to the touch. Kidney cells are rich in sugar and amylan. In countries where dates are grown, the date palm bud is considered a delicacy. Naturally, no one destroys the tree for this, they use palm sprouts that are removed during the growth of the palm tree and caring for it.
The kidney is designed so that its lower part, which produces stem cells, builds them the same size. Therefore, the trunk of a palm tree does not change in diameter as it grows. True, with a lack of nutrition, the trunk may shrink and then return to its previous size again. The number of feed-carrying channels in the bore does not change, and their diameter decreases. Thus, it is possible to determine by the palm tree whether it had problems in growth during the period of its life.
The kidney is very well protected from external influences. It is not affected by weather conditions, pests, and even after a fire on the plantation, the bud remains intact. In most plants, if the growth bud is damaged, it will be replaced by a new one, on the side. The date does not have such a privilege - damage to the bud will lead to the death of the tree. Therefore, the date palm is the champion of the plant world in the degree of kidney protection. It is located approximately 70 cm from the top and is laterally protected by thick leaf bases. During the day, the kidney temperature fluctuates plus or minus one degree! And this is with temperature drops of about 30 degrees in winter, the temperature inside the kidney is constant - 18 degrees.
The trunk tissue grows from top to bottom, the bud moves upward, leaving behind the trunk of the palm tree. Inside the bud of an adult tree, there are leaf shoots that will appear only after 4 years. Stem shoots remain at the bottom, while young leaves grow upward. The angle at which the leaves grow in relation to other leaves is constant and is a genetic trait of each species. When the sprout breaks upwards, the base of the stem remains inside the tree. The base of the stem is made of strong fabrics, laid on top of each other in a criss-cross pattern. This fabric, about 60 cm wide, covers the base of the stems. The top of a palm tree is like a panicle, where the branches are wrapped in a strong cloth and, as it were, are attached to its end.
As the leaf grows, the fabric dries from top to bottom, leaving behind rings of dry and tousled threads. When the tissue weakens, the branches begin to fall off under their own weight.
On the bud there are about 100 embryos of leaves and every year about 30 come out. The arrangement of branches, phyllotaxis, is the same for each species. The date palm has three spirals, three successively growing leaves close the circle, 120 degrees. between them. By the way, the spiral can be left or right. It doesn't make any difference in the life of a palm tree.
Now that we have gotten to know a little about the structure of the date palm, it is clear that there are leaves that begin to fall down and prevent us from carrying out work in the crown of the tree. The old leaves are removed, leaving the leaves at an angle of 45 degrees. and less. Such pruning rules give us about 60-70 leaves. It is customary to leave about 75, but experiments have shown that in the south of the country, due to high solar radiation, 60 leaves are enough. During the year, about 30 more young are added to them.
It is done like this. There are two people working. One bends a branch, the other cuts it down.
The saw is powered by the tractor's hydraulic system. The mechanism is light and powerful, but "tied" to the pipes. The stalks of the stalks are much stronger and are covered with the same mesh shell that gives stability to the tree. The saw does not take them, another approach is needed - this time with hydraulic shears, which do the job well. They are not suitable for soft green branches. In addition, the stalks are above the level of the branches left on the tree, and it is more convenient to get them with scissors. It's a shame that there isn't one tool that works for everything.
After pruning, all leaves are dropped to the ground.
Summing up, we got a clear idea that many processes, up to 90%, can be attributed to a universal manipulator with remote control and telemetry, where we assign a special role to mechanical solutions, as well as the simplest remote synchronized control and adaptation of machine vision functions
After that, we collect the leaves with such a mechanical rake to the center.
It's the turn of this hellish machine. The dust is a pillar and is sometimes visible from kilometers away! On the longitudinal axis of this machine, knives rotate, which break dry leaves and turn them into straw.
After that, the "straw" is collected in large bundles, like those that can often be found in photographs of harvested wheat fields - cylindrical or rectangular (depending on the machine)." The author's translation of the article was approved by the author of the original. A source.