Abstract

A commercial program for the production of oil palm seeds has been running for several years in Coto, Costa Rica. It is based on genetic materials brought from research stations in Asia and Africa in 1968. Deli x AVROS materials are used around the world due to their productivity and high range of adaptability. However, since 1986, a process of experiments in the commercial areas of Deli x Ekona and Deli x Calabar have revealed alternatives to AVROS materials.

Results from the first few years have shown that Ekona and Calabar materials are as productive as AVROS. They have a smaller growth rate, and Calabar materials have a shorter leaf length. In addition, the ratio leaf area/leaf dry weight is higher than in traditional materials. Ekona materials have a greater oil to bunch ratio.

Contemporary research in Coto seeks the answers to a greater understanding of this knowledge. Researchers are also analyzing the behavior of older palms grown from these materials and looking for the density that will bring maximum economic returns as well as exploring the potential production of other lines which have still not been commercially utilized.

Introduction

The commercial production of oil palm seeds started in Coto, in the south occidental region of Costa Rica in 1975 under The Oil Palm Research Program (PIPA). Since 1985 production has accelerated rapidly thanks to the renovation of plantations and to the export of seeds. The techniques used are similar to those employed in other research and production centers around the world such as Marihat in Indonesia, NIFOR in Nigeria, OPRC in Ghana and IRHO on the Costa de Marfil. They are essentially based on the controlled pollination of (dura) type palm with pollen obtained from pisífera type palm, progenitors are selected through several years of observation in experiments established for such ends (Hardon, J.J; Thomas, R.L. 1968; Gascon, J. P., de Berchoux, 1964; Richardson, D.L., 1985).

As part of the exchange program of genetic material, from 1968, lineage of the material E. guineensis were obtained from different origins, which came to later constitute one of the most valuable collections of oil palm germplasms in the world. In this manner, materials with an advanced breedingdevelopment were introduced, such as Deli dura, which originated from Socfin research station, Chemara, Banting (Malaysia), Dami (New Guinea); AVROS, from the  Banting station; Ekona, from the Lobe station in Cameroon and the Kade station amongst others.

Owing to the productive capacity of the materials originating from Deli x AVROS around the world, (Hardon, J. J., Thomas, R.L., 1968), crosses of this type were used in the first commercial seed production in Costa Rica. During the last decade, this type of material dominated these new planting areas.

In 1985, there was a lot of interest in exploiting the potential of other lineage introduced and this was extended to trial tests of the progeny of the Ekona and Calabar groups. Experiments were set up for such ends and in 1989 commercial areas were planted around Coto, Palmar and Quepos with materials from the Deli x Ekona type and Deli x Calabar, in addition to the traditional Deli x AVROS.

The results presented are a summary of the behavior generally observed in the three types of materials planted in experiments in Coto since 1985 and in the commercial areas established in Coto and Palmar.

General Characteristics of Some Parental Lines Introduced in Costa Rica

The population of Deli dura is most commonly used around the world as a female line for the production of seeds; owing to high yields, vigorous growth and good characteristics of the bunch (Rosenquist, E.A., 1986, 1992).

The AVROS line is at the same time the source of more ample pisiferas used in Malaysia and Indonesia, owing to its good production capacity when it is combined with palms derived from the population of Deli dura. It gives high yields, a good rate of oil extraction and precocious progenies, in addition it provides vigorous vegetative growth (Corley, R.H.V., 1992; Rosenquist, E.A. et al ., 1990).

The Ekona population, developed in Cameroon, have been used in seed production programs in this country. They are characterized for possessing a high number of bunches, moderate growth, a good bunch composition, and in some lines,  a high percentage of oil in the mesocarp. Some progenies have also shown resistance to the Fusariumwilt (Rosenquist,E.A. et al ., 1990; Sterling, F.,1991).

Progenies originating from Calabar (Nigeria) have become good sources of pisifera in some research stations, such as Sabah (Rajainadu, N. et al ., 1986; Chan, K.W. et al ., 1986), Kade (Wonkyi - Appiah, J.B., 1974) and NIFOR (Okwuagwu, C.O., 1985; Van der Vossen, H.A., 1974). In Coto they have shown a reduced vegetative growth, a high leaf area compared to the dry leaf weight and moderate bunch characteristics.

Materials and Methods

The experiments and commercial areas which are evaluated are located in Coto and Palmar (on the South Pacific of Costa Rica). The region of Coto is characterized for its high rainfall (4100 mm) and temperature (27°C), in addition it has a high humidity level and relatively low solar radiation. The rainy season lasts from April to November. The dry season is not very well defined, lasting between December to March. In Palmar, the annual rainfall is from 3600 mm, the dry season is more defined than in Coto, and has higher solar radiation and lower relative humidity.

The experiments' evaluation techniques consist of observation periods looking at the incidence of crown disease (CD-SR), bunch production, vegetative growth, characteristics and quality of the bunches and the rate of fruit dispersal.

The evaluation of crown disease is normally carried out during the first two years of the plant's life, when is common the apparition of the earlier CD-SR simptoms (de Berchoux, C., Gascon, J.P., 1963; Blaak, G., 1970; Chinchilla, 1987).

Production was evaluated in weekly cycles, noting for each palm, the number and weight of bunches produced during the first three years after the start of the harvest. The evaluated growth variables were the height of the trunk and the area and longitude of the leaf. These were measured biannually following standard evaluation methods (Corley, R.H.V. et al ., 1971).

The characteristics of the quality of the bunch were evaluated following the Blaak, G. et al . (1963) method, which permits the separation of the bunch into each of the components, the bunch's fruit, the mesocarp in the fruit, the oil in the mesocarp and the oil in the bunch, according to its total yield.

The pattern of fruit dispersal was evaluated in the dry and rainy season, registering the quantity, weight and percentage of fruits which fall in four-year-old oil palms.

In observations carried out in the commercial areas of Coto, the incidence of the crown disease-spear rot in examples of AVROS and Ekona is similar. Its incidence waves around 5%. In some experimental areas, the percentages of affliction in AVROS and Ekona have reached from 8 - 12%, perhaps owing to the higher genetic variability of the subjects being evaluated. The Calabar lines have been observed as having greater variation, presenting an average close to 8% of incidence (Sterling, F., Alvarado, A., 1994).

As regards bunch production, results from commercial planting in 1989 in the regions of Palmar and Coto, allow for the establishment of the masculine lines Ekona and Calabar posing as a very similar FFB yield potential to the materials planted in the AVROS line. In Palmar, Ekona lines produced 48.5 TM/ha of bunches between 21 and 56 months of age, similar enough to those obtained from those derived from AVROS. In Coto, yields observed from Calabar and AVROS materials, are found to be slightly superior in Calabar progenies, between 21 and 44 months of age but this is surpassed by AVROS progenies from this age onward. The bunch production accumulates up to 56 months from 40.2 TM/ha in Calabar against 41.3 TM/ha obtained in AVROS materials. (Table 1, Fig.1 ).

In research in Coto, the same Ekona progenies  planted in Palmar, presented a similar yield with respect to AVROS materials. The average production for Ekona materials was from 120.6 kg palm/ year (17.1 TM/ ha/ year) while those crosses with the Deli  x AVROS origin produced 127.6 kg/ palm / year (18.1 TM/ ha/ year). However, more diversity was noted in the Deli lines x Ekona whose yield oscillated between 14.4 and 21.3 TM/ ha/ year.

The production potential of bunches in the three sources of commercial materials all had similar results. The choice of one determined commercial line must be substantiated in other aspects, generally considered secondary, although no less important as precariousness, vegetative growth and adaptation to regional conditions where the new plantation is established.

As regards vegetative growth, table 2 presents the behavior of those progenies originating from Ekona and Calabar in relation to AVROS. The new materials presented less trunk height than those derived from AVROS, the Calabar line being the smallest. With respect to the fronds longitude, Calabar materials present the least reduced value, those derived from Ekona possessing an excessively long petiole, resulting in a similar total foliage to that of AVROS. Another notable aspect is that the progenies of the Calabar origin are its elevated leaf area ratio (leaf area/ dry leaf weight), ratio which has been associated in a positive form with the rate of photosynthetic efficiency (Breure, C.J., 1987).

Reduced vegetative growth observed especially in descendants from Calabar and Ekona, constitute the principal competitive element of these two materials, above all from the perspective of increasing the density of planting (Calabar) and prolonging the useful life of the plantations, in environments where vegetative growth is seen to be favored by environmental conditions.

Table 3 and Figure 2 show the behavior of some variables which characterize bunch quality in the three types of described materials.

Lines originating from Ekona present high percentages of fruit mesocarp, mesocarp oil and bunch oil. At the same time, it has been observed that the quality of these bunch components in AVROS and Calabar progenies are similar, although in the posterior there is a higher production of kernels.

The oil palm breeders have centered their interest in lines which present high levels of oil and kernels in the bunch, above elevated bunch productions, this is supposed as an increase in the economic efficiency of the activity, lines with high levels of extraction imply a reduction of costs, relating to a lower quantity of bunches to be harvested, transported and processed.

Evaluations concerning fruit dispersal generally presented different percentages between the AVROS and Ekona lines in the rainy season. The percentage of fruits accumulated up to 10 days after the start of dispersal was better in the Ekona line. Derivatives of Calabar showed a significantly better proportion than AVROS in days 9 to 12 (Table 4).

The collection of fruits detached during the ripening, cutting and transportation of bunches, represents one of the most important concerns at harvest time; a planting material with less fruit dispersal, will more positively improve the efficiency of the activity.

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