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Recommended method for selecting good parent palms and producing Tall-type seednuts

By R. Bourdeix, V. Kumar and V. Mataroa
Updated 09/04/2018

The method consisting in simply harvesting seednuts on "best" palms and replant them is that scientists call "mass selection using open pollination". Although this method has been practiced by thousands of farmers for millennia, its efficiency remains very limited. It can be improved slightly by using best selection criteria but, even in this case, for each generation of palms in farmer's fields, the yields’ improvement will be very probably no more than 5-10%.



Nothing can replace a well-designed, regular and sustainable breeding program conducted by well-trained professionals. Very few countries have succeeded in creating and maintaining such a program, which requires the yearly planting of at least ten hectares of fields breeding experiments.


Proposed method for selecting good parent palms


In the expert opinion, the processes of parent palm selection presently conducted in farmer’s fields in most of Pacific countries do not provide significant improvement of the existing varieties. In many cases, selection is only visual: within a plantation, 50 to 80% of the existing palms are often selected as parent palms for seednuts production. Thus, in the expert opinion, these selections processes are only conservative, meaning that the progeny of the parent palms generally have the same genetic value than the population from which where they are selected. In order to improve the efficiency of the mother palm selection processes, we propose a method based 1) on a higher selection rate, only 10% of the existing palms 2) based not only on visual appraisal but also on fruit analysis conducted directly in farmer’s fields; and 3) securing all the data in a comprehensive database.
Recent fields trials conducted in the Cook Islands indicate that the numbering of the palms is crucial. The expert strongly recommend buying sets of already number aluminium tags (from 1 to 1000) that will be tagged with nail on the east side of the palm at about 1.80 from the soil, in addition to band painting. By using these tags, if another agricultural officer comes back 15 years later, he/she be able to find the palm again.

We created seven data sheets or forms for recording all the requested information: first about farmers and farms; 2) palm localisation, 3) Palm characterisation, 4) and 5) two methods for mature fruits analysis, please chose one; 6) tendernut analysis and 7) Nursery test for discarding hybrids. Both the relevant Excel file and the seven individual data sheets are available online for download.
Implementing such a process needs preferably a team of two or three workers, of which one agricultural officer and a coconut climber/harvester. The total working time is probably between one and two hours per selected palms, including the nursery test. Agricultural officers should ask for temporary recruitments of workers when needed, and obtain it from the Ministry of Agriculture, as this will be funded on CIDP project budget.



Proposed method for selecting good parent palms
Taking into account the composition and the quality of the fruit
for Tall-type seednuts production in farmer’s fields
R. Bourdeix, V. Kumar and V. Mataora, 2018


Selection process
Technical details
1
Select the farm and record information on the farmers and its farm
Use the form: Coconut seed system - 1 - Farmer data sheet.pdf.  Family and given name, gender, age, identity card number, phone, email if any (or the email of somebody from the family) : area (ha) of the farm, main crop, second crop, third crop, approximate number of coconut palms.
2
In the plantation, select 20% to 30% of the palms, based on visual aspects of the palm and indications provided by farmer and other farm workers, if any.
Use the two forms: “Coconut seed system - 2 - Palm localisation sheet.pdf” and “Coconut seed system - 3 - Palm characterization sheet.pdf”. Select palms with plenty of bunches full of fruits; avoid extreme value of stem girth and vertical growth when compared to the average of the population. Farmer’s choice should be taken also into account. Sometimes farms workers know the palms better than the farmer itself does, so do not forgot them.
3
Mark the palms with a 3 cm yellow band paint at 180 cm from the ground, and with under a palm identification number
Temporary mark pre-selected palms. Number should be for instance A18VK001 for the first palm marked in 2018 in farm A by Vijen Kumar. Double this mark for palms with special characteristics if any.
4
Harvest at least 10 mature fruits and two tender nuts on the preselected palms and mark them with the palm number
To be done with or without climbers according to the palm heights. Mature fruits must be completely dry, with brown grey skin but with water inside (you ear water sloshing), and without apparent disease or wound. Harvest tender nuts at optimal stage, depending on countries (kernel 1 to 6 mm thickness in average).
5
For each palm, select two average looking mature fruits and two tender nuts; with portable scale, conduct fruit analysis on these fruits.
To be done in the fields. For mature fruits, choose and fill one of the two forms: “Coconut seed system - 4 - Mature Fruit analysis - Method 1 (complete).pdf” or “- 5 - Mature Fruit analysis - Method 2 (pigs feeding).pdf”. For young fruits, use the form “Coconut seed system - 6 - Tendernut fruit analysis - Polynesian method”. If possible, take pictures of selected fruits with a camera or a phone having GPS; this will help you to get latitude and longitude.
6
Use the Excel Data sheet:”SPC-CIDP-PRAG07 Parent palm selection.xls with its seven sheets (visible at bottom).
7
Calculate fruit quality indexes (already done on Excel template)
Mature fruit quality index: (kernel weight)/weight of whole fruit without the free water: the highest values are fruits with thin husk and thick kernel, and often average-sized fruits. Young fruit quality index: weight of the water divided by the weight of the whole young fruit. Young fruits with plenty of water and thin husk are preferred.
8
Use data on Excel file to select 10 % of the best palms of the plantation (a third of preselected palms in Excel file)
Among pre-selected palms, we recommend to start to discard the 5% palms with heaviest fruits and the 10% palms with lightest fruits. Then select for high values of the fruit quality index and other favourable characteristics./
9
For each selected palm, pack a bag of seednuts, write the palm label on the bag and send it to the nursery
A nursery test will help to check if some of the chosen palms are hybrids of progenies of hybrids. Final selection will exclude such palms. The resulting good seedlings will be the first to be released to farmers.
10
Make seednuts grown and germinate in separate small seedbeds labelled by farmer, date and palm numbers, and check if they are yellow or red sprouts
Use the form: “Coconut seed system - 7 - Nursery test for discarding hybrids”. If the palm is of brown or green colour, and if there are yellow or red sprouts in its progeny, the palm is probably a Dwarf x Tall hybrid or a hybrid progeny. Discard it from selected palms if its progeny counts more than one yellow or red sprouts, except if the palm have very special characteristics such as sweet husk.
11
Update the Excel file taking into account the nursery test
The final result should be preferably selection of 10% of the palm of the plantation and 20% to 30% of the pre-selected and analysed palms.
12
Mark all the selected palms with a 15 cm red painted band up the yellow band
Permanent marking with durable paint and aluminium tags nailed on east side of the stem at 1.80 cm from the ground.
13
Make final checking of the data and send a copy of the Excel file to Extension services, Research services and the Curator of the National Genebank if any.
Official recorded transmission help the data to be secure and duplicated.

Additional advices: if the coconut plantation is constituted by a very special variety, which is rare or not found in other places, it is advised to maintain and breed separately this special variety. If the plantation is constituted by a common variety, shared by many farmers around the village or within the country, diversifying seed sources is advised. In the past, some Polynesian farmers may have harvest many coconut seednuts in the same palms and plant close together; so very probably, in some plantations, palms planted close together are half or full sibs. Thus, to avoid inbreeding depression (crosses beween half or full sibs), when planting a new field, it is advised to get the seednuts from different locations, such as different coconut plantations or different places within the same plantation. Coconut exchanges between farmers are strongly advised and should increase. Tall-type varieties reproduces mainly by cross-breeding, but self pollination also occurs at the period when the emission of inflorescence is the fastest. One of the main challenge for seednut production is to avoid seednuts conceived by selfing, because the inbreeding depression will result on a reduction of the yield of 20 to 30%. Thus, seednuts harvested during the time when the rate of emission of inflorescences is the slowest will yield better than average.  When the rate of emission of inflorescence is it the lowest? This needs to be checked, but probably during or at the end of the dry season. The rate of selfing increases with the rhythm of inflorescence emission and bunch production. This rhythm depends on the individual vigour of the palm and on climatic conditions. When selecting good-performing palms in the best plots, one may select palms with a higher tendency for selfing. Consequently, their progeny suffers from an inbreeding depression resulting in lower productivity. 


Link with traditional practices
Here under is a short movie on a farmer's method for planting coconut in Atiu Island, Cook archipelago. This movie seems important for two main reasons:
  1. This is the first documented case in Polynesia where a farmer plant many coconut palms and remove the baddest. I found that most pacific farmers are generally very conservative and, once a coconut palm is planted, they keep it for a long time, be it a good or a bad producer. Jokingly, we could say that most of these farmers treat coconut palms as members of their families. This movie demonstrates that I was wrong and that, at least in some cases, farmers are applying the technique that is recommended in our website: to plant more coconut palms and to remove those which are not producing well.
  2. We were surprised to see that this farmer is applying the criteria for selecting coconut fruits similar than the one developed in the method proposed here.There is a scene where the farmer is discarding the biggest fruits and keep only the one with thin husk and big coconut inside. So our method is well connected to some traditional practices, here in Atiu, Cook Islands. It's pleasant and reassuring, because we did not know the link with traditional practice at the time when we developed this method.



Mass selection using open pollination
For other breeding methods, see the section on Advanced methods for improving local tall-type populations.
The majority of world coconut is derived from mass selection, informally done by all growers. At the end of the 19th century, large plantations have been established by importation of fruits from a region known for its production (Ziller 1962). In most cases, the seednuts were selected according to their specific characteristics: some preferred large and heavy fruits (Zuniga 1969), others medium-sized fruits preferably round-shaped (Apacible, 1968). The genetic structure of the coconut populations has been modified by successive selections based on fruit characteristics.
From the breeder’s point of view, there are three variants of mass selection, based on the reproductive system used - mass selection using open pollination, intercrossing or selfing (Bourdeix, 1988). 
Mass selection using open pollination has been practiced the most. The advantage of the method is its simplicity; the seednuts are collected from the palms that present attractive characteristics at a certain time or over a period. The progenies resulting from open pollination are the basis of an improved population which will then undergo other selection cycles. This method leads to variable results. Even in the most favourable cases (yield improvement of only 14% per cycle), the drastic selection necessary to obtain an improvement considerably reduces seednut production potential. One generation of multiplication is inevitable. Thus, it is better to use this generation for the evaluation of the parents based on the performance of their progeny. The only advantage of mass selection using open pollination is its simplicity.
Mass selection using intercrossing appears more effective, as it allows for a strict selection of pollinators while retaining the potential for large seednut production. This method was applyed in Vanuatu. Mass selection using self-Pollination induces an inbreeding depression  and is not recommended for seednut production.

The study on efficiency of mass selection method using open pollination is characterized by a number of divergent results (from 0 to 14 % improvement per cycle). From 1960 to 1990, this point was the main scientific controversy in the coconut research community. The difference may find its origin in the reproductive character of the Tall varieties. Although the latter are preferentially allogamous, there is the possibility of natural selfing. The rate of selfing increases with the rhythm of inflorescence emission and bunch production. This rhythm depends on the individual vigour of the palm and on climatic conditions. When selecting good-performing palms in the best plots, one may select palms with a higher tendency for selfing. Consequently, their progeny suffers from an inbreeding depression resulting in lower productivity. The rhythm of inflorescence emission also varies with seasons and so do the selfing rate.
A full study was conducted by the expert long time ago in Africa (Bourdeix, 1988). It appears that the best selection processes could generate a progress of only 14% per generation. This occurs only when appropriate selection criteria are applied by recording fruit production and composition during 4 full years, and when only 5% of the palms are selected from producing the next generation. So, what is presently done is most pacific islands: - selecting palms only on visual aspect and using 30% to 80% of the palm for producing the next generation - very very probably leads no genetic progress - same value of the parent palms and the next generation. 
Another conclusion of this study is that strong genetic and environmental negative correlations exist between the number of fruits and the weight of the fruits. Be care that, when selecting only for heavy coconuts, you will well succeed to increase fruit and nut size of the progeny, but you will also reduce its yields in term of weight of kernel, copra and oil per hectare. You will  obtain a progeny producing a few number of big fruits. The best is to select on number of fruits and fruit quality index - medium fruits with thin husk and thick kernel.
The level of selection pressure conducted at the nursery stage is also very important. Seedlings derived from self pollination are generally less vigorous than hybrid seedlings. It is probable that the selection traditionally conducted by farmers in their fields have the effect of eliminating a significant proportion of seednuts resulting from self pollination, although this was never formally demonstrated. The worst situation could be when all the germinated seednuts are released to farmers because the demand for planting materials is greater than the capacity of production. Such a situation happens often in development projects, where the desire for success can lead to overloaded nurseries.

References
Apacible, A.R. (1968). Selection of coconut. Sugar news (Philippines). 44: 93-98. 
Bourdeix, R. (1988a). Efficacité de la sélection massale sur les composantes du rendement chez le cocotier (Effectiveness of mass selection based on yield components in coconut). Oléagineux (France). 43, 7: 283-295.
Bourdeix R. (1999). Coconut selection and breeding. Pp. 117-196 in Modern Coconut Management (J.G. Ohler Ed). Intermediate Technology Publications, FAO, Universeteit Leiden.
Labouisse J.P., Sileye, T., Morin, J.P., Hamelin, C., Baudouin, L., Bourdeix, R. and Rouzière, A. (2004). Coconut (Cocos nucifera L.) genetic improvement in Vanuatu: Overview of research achievements from 1962 to 2002. OCL 11. (4): 354-61.
Labouisse J.P., Sileye, T., Morin, J.P., Hamelin, C., Baudouin, L., Bourdeix, R. and Rouzière, A. (2004). Coconut (Cocos nucifera L.) genetic improvement in Vanuatu: Overview of research achievements from 1962 to 2002. OCL 11. (4): 354-61.
Ziller, R. (1962). La sélection du cocotier dans le monde (Coconut selection throughout the world). Oléagineux (France). 17(11): 837-846.
Zuniga, L.C., Armedill, A.L. and de Gala, D. (1969). Maternal and paternal selection on coconut. Philippine Journal Plantation Industry.  (34): 9-16.