The first thing that a durian farmer or grower must do right the first time is when sourcing for durian saplings.
The issue is not much about getting a fair price for the saplings bought but rather buying the correct clone type saplings that he/she intends to grow.
The mistake that could happen (and it happens quite often, frankly) is when a grower buys the wrong clone type saplings only to realize it after the tree has bear its first fruit. This will be 4-5 years down the road, imagine all that time and money spent.
This mistake in sapling purchase is exacerbated by a growing community of inexperienced individuals or middlemen selling durian saplings to the general public which were bought from unknown sources or even nurseries. These type of people are in it for a quick buck. I would advice against buying any saplings from night markets or online sellers.
In verifying the correct clone type saplings, some of the clones do exhibit specific characteristics mostly in its leaf shape or form or even color (eg: the Musang King or D197 has a wavy form at the edges of its younger leaves) while the Duri Hitam or D200 clone exhibits droopy branches. These characteristics could help the farmer or grower to identify the clone prior to purchase.
The issue nonetheless, some different clones exhibit similar or even identical characteristics while some does not even have special characteristics at all.
The safest bet for a farmer or grower in getting the correct clone types is by sourcing saplings from an SPBT certified fruit plant nursery. SPBT or Skim Pengesahan Bahan Tanaman (Planting Material Verification Scheme) issued by the Department of Agriculture.
This SPBT certification scheme does not only apply to durian saplings but to most tropical fruits such as mango, jackfruit, pineapple and mangosteen (fruit trees which have a few cultivars) in which the Department of Agriculture shall verify the clone/cultivar type and shall record the origin of the matured trees where the scion or young stem/shoot was taken for grafting by the plant nurseries.
These record shall document the verification and traceability of the scions or other vegetative propagation plant materials that the nurseries sourced for its clone seedlings grafting activities.
Having said that, this scheme is only applicable for fruit trees having various clones/cultivars breed and it does not apply to heirloom saplings.
Farmers and growers could sourced their durian saplings from these certified fruit nurseries which are listed in the Department of Agriculture's website at http://www.doa.gov.my/index.php/pages/view/399. This list will be updated periodically.
As for myself, I sourced my saplings from three certified nurseries in Kajang, Muar and Bidor. I also once bought two Musang King saplings from Putra Mart, a plant nursery managed by Universiti Putra Malaysia (UPM), formerly the Malaysia Agricultural University. This university managed plant nursery doesn't have an SPBT certification but I do trust them.
I would like to advice that not all nurseries with saplings planted and sold in polybags bearing the Department of Agriculture's logo are SPBT certified. Likewise, a normal polybag without the department's logo does not indicate that particular nursery doesn't have an SPBT certification.
Why buy grafted durian saplings?
In Malaysia and I would believe likewise in other durian producing countries, there are 3 categories of durians. One is the native durians, another is the clone durians. The last category is the wild or jungle durian.
The native durians are also called 'kampung' durians meaning although they are not considered heirlooms but these fruits are produced from matured trees which grew naturally from seed.
The reason I would not call these kampung durians as heirlooms is because their trees grew from seeds which is a result of sexual reproduction between a male gene and a female gene either from the same tree or genes (male or female) from other kampung durian trees.
Kampung durians are inconsistent in taste and other characteristics. They have large seeds with thin flesh and mostly are pale cream or even off-white flesh coloration. Some of it have watery flesh as well.
Because of this, kampung durians have lower commercial value since buying kampung durians is like rolling the dice. It doesn't have a standard quality or fruit expectation and even the sellers don't really know what to expect until he opens the fruit for the buyer to see.
The clone durians come from trees which were grafted. These durians have much more commercial value, better tasting, better flesh coloration and overall consistency in terms of flavor, shape and weight.
In Malaysia, clone durians are the ones with registered names starting with the word 'D' followed by a number, eg; D197, D99 or D168. It has to be noted nonetheless, that some clones doesn't have a 'D' initial. This is by virtue of it not registered with the Department of Agriculture. Examples of this are durians which originates from the northern state or Penang.
Clone durians comes from trees that were originally produced from a scion wood taken from a matured tree of a known clone and then grafted with a rootstock of a native or kampung durian. This is an asexual reproduction hence the word 'çlone' durians.
The reason of having a native/kampung rootstock is that these rootstocks have better root disease resistance, drought tolerant and better adaptability to local soil conditions.
It has to be noted, while native/kampung rootstock are the normal practice but the best rootstock is still the seedling from a jungle durian (durio graveolens, durio oxleyanus etc.) This means other rootstocks which do not belong to the durio zibethinus sub-species.
These jungle durians are considered heirloom. Its tree are quite hard to find especially in Peninsular Malaysia although it still exist in deeper areas of the forests. The reason behind this is deforestation to make way for commercial crops or even clone durian plantations.
It is said in research papers that these non-D. zibethinus sub-species are resistant to P. palmivora disease due to better adaptability in continuously wet and soggy soil where it is normally found growing.
In terms of the fruit, jungle durians have an unpleasant taste, some people reportedly experienced nauseating effect when consumed in large amounts. Physical appearance wise, it has longer and winding thorns.
Types of durian sapling grafting techniques
In Malaysia, there are a few grafting techniques that is used by nurseries and individual grafters. The types of grafting are:
1. Eye bud grafting
2. Wedge grafting
3. Multiple-legged grafting
4. Adult grafting
I will discuss on the first 3 types of grafting techniques which are the most common. The first technique in which 90% of durian saplings purchased at local nurseries are produced from.
Eye bud grafting is done by inserting a small length of a scion wood which has one eye bud that has not open. It looks like a grain of rice. As can be seen below, the eye bud on top is already open which makes it unviable.
This small straight length of scion with one unopened eye bud is then cut into half longitudinally. This scion is then put onto the rootstock with its cambium layer exposed (scion cambium onto rootstock cambium touching together).
The scion will then be wrapped in parafilm with the eye bud left free (unwrapped). After 1 week the eye bud will break and grow. In a few weeks it will form the main growing leader of the sapling.
The rootstock stem above the grafted zone is cut or could also be left as is (most cases this portion will die-out). Any shoots growing from the rootstock stem must be remove since leaving this shoot to grow means it will grow out to be a sapling of the rootstock.
The inherited genetics of the intendedDi clone sapling shall be identical with the tree that the scion was harvested.
In Thailand, wedge grafting is the grafting technique of choice. As opposed to Malaysia, 90% of saplings for sale in Thailand are wedge grafted.
This grafting technique is different from eye bud grafting whereby the scion harvested is use entirely and is cut at the bottom end to form a wedge shape.
The rootstock is then prepared by cutting at a suitable height and then the cut end is slit in half to match the length of the wedge on the scion. The scion will then be inserted to the rootstock and wrapped together with parafilm.
Multiple-legged grafting is combining 2 or 3 rootstocks with 1 rootstock that have underwent prior grating using either the first or second technique.
The outer skin of these rootstocks are delicately sliced to expose the cambium layer whereby it is then stick together and allowed to grow. What is then produced is a sapling with a single main stem having multiple rootstock.
As can be seen in the above photo, the polybags on the front row are all multiple-legged saplings (in this case 2-legged). Theoretically, the obvious benefit for the plant having multiple root sets is increased nutrient and water uptake thus increases its its growth rate.
However, this theory could not be ascertain since there are not many adult durian trees planted with this grafting technique. This technique has only went into the mainstream about a couple of years ago.
Prices of the multiple-legged grafted saplings are sold at a premium compared to the eye bud and wedge type grafts.
What size of durian saplings to buy?
Often times a durian planter or a grower will need to decide on the size of the saplings that he/she intends to purchase.
In general, this decision lies mostly on cost considerations since the bigger the size of the sapling the more expensive is the price. Outside of price, the consideration, advantages and disadvantages or selecting different size of saplings will be discussed in the following paragraphs.
The prices of durian saplings is determined by the height. The definition of height in this case is the measurement from the grafted point to the top most shoot of the plant's main leader as show in the below photo.
Most amateur growers when purchasing saplings at nurseries would carry an understand that the height is measured from the base of the stem (soil level) to the top most shoot which is not the case.
Serious planters with high investment budgets would normally select 4ft - 5ft sized saplings and the reasons behind this are:
1. More disease resistance
2. Will not be smothered by weeds and undergrowth easily after transplanting
3. Faster acclimatization to farm conditions leading to faster growth
4. Faster maturity since it's a bigger and older when planted
5. Better drought resistant
I will point out that sourcing for a bigger seedlings which are defined as APMs (advanced planting material) will cost significantly more compared to normal size saplings.
The above photo demonstrates the different is size of APMs (back row) with the normal size durian saplings at the front.
In my case, I have a mixture of APMs and normal sized saplings reason being, apart from costs, the difficulty in transporting and handling the APMs until reaching its intended planting hole. The workers and myself would need to carry each of the APMs up to the hill terraces using manual labor.
Do's and Dont's in Caring for Durian Saplings (in polybags)
- Don't buy saplings via post even if you are familiar and have bought plants from them before. Post is not the same as delivered by the nursery's own transport
- Don't put the saplings over concrete surfaces, pavements, road surfaces or any
similar surfaces. These surfaces gets hot during the day and will stress the sapling
- Don't forget to water the saplings on a daily basis. Saplings inside polybags
require more water than those already planted on open soil
- Do poke additional holes on the bottom of the polybags since drainage holes on polybags are mostly on the sides. Often times saplings will have root root due to water accumulation on the inner bottom of the polybags