Friday

False and true ideas about coconut hybrids


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By Roland Bourdeix
Yes! imagine you succeed to find the most performant coconut hybrids (which is quite difficult in 2017 in the Pacific region); If you plant them and forgot them, leaving them alone with mother nature, without caring for them and without bringing them any kind of fertilizers, picking up all the nuts, husk and leaves; then these hybrids will only produce well for the first fifteen to twenty years; and then your soil will probably be depleted, emptied of its mineral and organic elements. Hybrids are very powerful varieties, able to draw large amounts of mineral elements from the soil to ensure high production. Hybrids could be compared to luxury cars. Can you hope that a luxury car consumes as little fuel as the smaller ordinary car model ?

No! hybrids are not foreign varieties, imported, and unsuited to local conditions. Hybrids are mostly made by crossing two varieties that have been present in the country for hundreds of years or more. It's easy to teach farmers how to create hybrids from varieties already present in their fields and gardens.

Yes! There is a special age when hybrids are more fragile than Tall-type coconut trees. This usually occurs between 4 and 7 years after planting. At this age the hybrids, if well planted, are already covered with hundreds of fruits and their root system is not completely implanted. At 5-6 years, most of Tall-type coconut palms produces only large stem and leave and bear no or only a few fruits. If you are really unlucky and if a cyclone or a very severe drought occurs just during this period, the hybrids will suffer more than the Talls, and some hybrids may even die while the Tall-type will survive. But since hybrids produce much more, it's worth planting hybrids or, more judiciously, having different kinds of both hybrids and Tall-types in your coconut plantation, in order to spread the risk of hazards and make your own ideas about your varietal preference.

Take care! some seednuts providers sometimes give or sale false coconut hybrids. Generally they harvest open pollinated seednuts on hybrids coconut palms and try to release them as hybrids or as Tall varieties. These are not actually true hybrid: the seedlings will not produce as much as coconut hybrids. In the case of a Dwarf x Tall hybrids, you will obtain a progeny mixed of Dwarf, Tall and Hybrid looking palms, with some good producers but also some palms with low yields.
When such a false planting material is released, recipient farmers often develop a bad opinion about hybrids. This is understandable because what they planted as hybrid is not real hybrid. In general, if in the nursery, you see about a quarter of the sprouts with yellow or red color, that means the seednuts are not hybrid, nor Tall-type, but seednuts harvested on hybrid palms. See also some examples of frauds and disproportionate prices in the internet for coconut planting material.

Farmers, please also care about what some stakeholders are saying regarding Tall-types and Hybrid coconut varieties. Yes, the kernel oil content is higher for Tall-type variety. Yes, copra millers and oil producers are winning more profit when buying a ton of coconut or copra from Tall varieties than when buying the same from hybrid varieties. Indeed, they recover a larger quantity of oil from the local Talls. However, if you look carefully from the farmer’s side, the issues are very different. In average, when planted in appropriate conditions, Tall-type varieties will yearly produce about 1.8 tons of copra containing about 1.2 tons of oil per hectare per year; in average, Hybrids (MRDxRIT for instance) will produce yearly 3.6 tons of copra containing 2.0 tons of oil per hectare. Therefore, farmers, please make your own calculation, please prioritize your own profit, and do not blindly follow the advises of some coconut stakeholders. On the other hand, sometimes there is an interest to market separately coconut products from Tall-types and hybrids (niche markets and future branding by varietal type); thus, setting up a traceability system would be useful to the coconut industry.

There are three main types of coconut hybrids, ranked by order of economic importance: Dwarf x Tall (D x T), Tall x Tall (T x T) and Dwarf x Dwarf (D x D) hybrids. In scientific papers, hybrids are often designated by the international code of their parental varieties, such as ‘MYD x WAT’. The first variety code cited designates the female parent (MYD or Malayan Yellow Dwarf). Regulations about hybrids commercial names have yet to be established. For instance, the hybrid MYD x WAT bears the commercial designations of PB121 in Africa, MAWA in Asia except in Thailand where it is known as Sawi Hybrid No 1. Here under is a short funny video from Brazil showing coconut hybrids having the Rennell Island Tall (from Solomon Islands) as male parent.

"Modern" coconut breeding only resumed after the Second World War, with the first surveys and systematic studying coconut varieties cultivated worldwide. This research provided an initial approach to the genetic diversity of the species. In particular, the originality of Dwarf type varieties was discovered: Dwarfs are characterized by early flowering, slow vertical growth, but also a tendency towards self-pollination, susceptibility to drought and insect attacks.
Many coconut hybrid tests were set up from 1945 to 1960. They consisted in crossing various local Dwarf or Tall varieties with each other. The experimental population used for that work was generally small. Most of the results indicated that hybrids were better than their parents.
For a long time, these studies remained mostly theoretical. Even though coconut hybrids displayed a high production potential, it was not known how to propagate them on a large scale. The absence of a reliable seednuts production technique prevented any distribution of those hybrids to growers. Some countries even turned away from that line of research because it did not seem to be leading to any practical applications. Development of seednuts production techniques dates back to the 1970s. By offering reasonably priced seednuts with good legitimacy, those techniques led to the advent of coconut hybrids.

About the Maren Hybrid - Malayan Red Dwarf x Rennell Island Tall
The Maren hybrid was created in the 1960s at the Yandina research station in the Solomon Islands. It is a cross between the Malayan Red Dwarf (MRD), used as the female parent, and the Rennell Island Tall (RIT). It was reproduced in various countries and subsequently improved in Côte d’Ivoire. Maren is the most widely used hybrid in the Pacific region.

Climate and crop management sequences determine coconut palm yields. Maren and PB 121 hybrids were compared in two similar experimental plots at the Marc Delorme Research Station. In a plot planted in 1971, the Maren flowered after four years, or three months after hybrid PB 121. However, in a plot planted in 1979, the Maren hybrid flowered after only three years, or two months before hybrid PB 121! On farms, the difference in flowering is even more pronounced.

Depending on the plots, the palms start bearing four to five years after planting. On immature palms, yields fluctuate between 39 and 94 fruits per palm per year. On mature palms that are 9 to 15 years old, annual production does not exceed 78 fruits per palm on average, as compared to 109 for PB 121. However, as the fruits of the Maren are much larger, copra yields are not much different to PB 121 at 3.4 tonnes of copra per hectare, or only 260 kilograms less than hybrid PB 121.
The fruits weigh 1.7 kilograms on average and contain a nut weighing from 1200 to 1300 grams. Copra weight per fruit varies from 279 to 310 grams depending on the plot conditions.
The results obtained to date are for the first generation Maren. Experiments in Côte d’Ivoire designed to create the second generation improved Maren have just been concluded. The progeny of the best RIT parent produced 5.3 tonnes of copra per hectare per year, or 128 nuts per palm, over the 9- to 13-year period. This shows an improvement of 31% more than the first generation Maren hybrid. These production data should not be extrapolated to true growing conditions, which are often less suitable. However, the relative differences between the first and second generation hybrids should be more or less consistent.
The Maren hybrid displays excellent tolerance to fruit rot caused by fungi of the genus Phytophthora, although it is susceptible to attacks by large leaf-eating beetles that are notably rife in the Papuan islands. The Maren hybrid was produced on Taveuni in the Fiji Islands prior to being replaced by the cross between the Malayan Yellow Dwarf and the Rotuma Tall. In the 1990s, the Maren was also produced under the name VIC 10 at Hacienda Victoria in Costa Rica, before being replaced by the Maypan, which showed more promise against LYD. In Côte d’Ivoire, PB 113 (CRT x RIT) is preferred to the Maren. Small-scale Maren hybrid production is still ongoing on the island of Upolu, in the Western Samoas. This cross is recommended for volcanic soil with good rainfall, except in Vanuatu where the foliar decay virus is rife.
The stem of the Maren hybrid begins with a marked bole, but rapidly narrows. At 17 years old, the stem, measured from the ground to the base of the first green frond, reaches 7.4 metres, or about 60 cm shorter than that of reference hybrid PB 121 in the same plot. Its large fruits are much rounder and heavier than those of PB 121, and are rich in meat and free water. Their colour varies from yellowish brown to reddish brown. They are oblong to pear-shaped, midway between the shapes of the fruits of its two parents. The inner nut is slightly round with a slightly conical-shaped upper section.


About Complex hybrids
The term ‘complex hybrids’ refers to crosses of a coconut hybrid with another hybrid or a variety. In the case of coconut, the first complex hybrids were created by the Indian farmers of Kerala (Bourdeix et al., 2005). These farmers selected natural hybrids COD x WCT from the seednuts of Dwarf coconut palm. Then, they harvested seednuts from the hybrid itself and planted it again. From this progeny, they selected again the brown-sprouted seednuts. Some generations later, they finally created a precocious and bright brown-fruited variety known as ‘Komadan’.

For the coconut breeder, the first experiment testing of complex hybrids was established at the CNRA Marc Delorme Research Station, Côte d’Ivoire in 1976 (Bourdeix, 1994). This programme essentially aimed at evaluating the genetic variability and searching for exceptional coconut palms that could be propagated rapidly when a method of vegetative propagation would become operational. This was quite ambitious, and some 30 years later, the development of coconut in vitro propagation technique has not progressed sufficiently to be used for this purpose. Recently, however, Dr Carlos Oropeza reported that his group has improved the technology which is projected to generate 100,000 embryos from a single plumule, which is a substantial advancement in in vitro propagation of coconut. In Thailand some three-way hybrids (D x T) x T and (T x T) x D were created in the 1980s to evaluate the genetic variability of these materials and to find out if these hybrids may be distributed to farmers (Petchpiroon, 1994). To date, results of these experiments are yet to be published.

In Côte d’Ivoire, some of the crosses tested were (D x T) x (D x T). This was supposed to give information about the inheritance of dwarfism, but interpretation was constrained by the heterogeneous nature of the experimental plot. Dwarfism in coconut is a manifestation of many different characteristics such as precocity, autogamy, small size of organs and slow vertical growth. In a (D x T) x (D x T) progeny, the progenies do not look like a typical Dwarf. The resulting palms have a wider bole and a faster vertical growth than the typical Dwarfs used as parents. They have an unexpected level of homogeneity. In the case of coconut, a single gene does not determine dwarfism. The corollary is the following: seednuts harvested from D x T hybrids do not give, at least in the first generation, a mix of Dwarfs, hybrids and Tall varieties. Many farmers indirectly produced complex hybrids, and the result will probably be not as disastrous as predicted earlier by scientists, as shown in Table 1, even if the best F1 hybrid remains superior to complex hybrids. 

Table 1. Fruit production of two complex hybrids and a D x T hybrid
in an experimental plot planted in 1987 in Côte d’Ivoire

Hybrid tested*
Type
Number of palms
harvested
Average fruit production
 per palm per year
(4-14 years period)
Mean
Standard Deviation**
PB121 or
MYD x WAT
( D x T )
Control
95
109
44
(MYD x WAT) x
(BGDxRIT)
(D x T) x (D x T)
Dwarfism segregation
348-339
94
49
(CRD x MYD)
x
(WAT x RIT)
(D x D) x (T x T)
No dwarfism segregation
211-208
81
52
*MYD: Malayan Yellow Dwarf; WAT: West African Tall; BGD: Brazil Green Dwarf; CRD: Cameroon Red Dwarf; RIT: Rennell Island Tall
**Mean of annual standard deviations

References
Batugal, P., Bourdeix, R., & Baudouin, L. (2009). Coconut breeding. In Breeding plantation tree crops: Tropical species (pp. 327-375). Springer New York.