Papers by Yohannes Samosir
The Planter
Asian Agri’s oil palm research station’s (OPRS-Topaz) breeding programme involves the complementa... more Asian Agri’s oil palm research station’s (OPRS-Topaz) breeding programme involves the complementary development of both seedling and clonal planting materials. From 2010-2018, a total of 18 clonal trials and 890 hectares of commercial clonal plots were established in two provinces (North Sumatra, Riau) and on three major soil types (volcanic, inland, peat). This paper reports on the early performances of the clones in the latter sites. Comparatively, elite clones only achieved 82 per cent and 85 per cent of their ortet fresh fruit bunch (FFB) and crude palm oil (CPO) yields, respectively. Analysis undertaken in five of the oldest mineral soil trials indicated either a negative or very low positive correlation between clone and ortet FFB yield, but correlations of oil to bunch (O/B) and annual height increment (Hi) were positive and highly significant, confirming the better heritability of the latter two parameters and their suitability as criteria for ortet selection. In clonal tria...
Coconut (Cocos nucifera L) plays an important role in the socio-economic life of many millions of... more Coconut (Cocos nucifera L) plays an important role in the socio-economic life of many millions of people in the tropical regions of the world. However, the genetic diversity of this species is being dramatically decreased by diseases, natural disasters and through land cleaning for the planting of the so called 'more valuable' crops. Coconut seed cannot be conserved by normal means as it is big and sensitive to drying (recalcitrant). Cryopreservation is an alternative conservation approach but as yet, this method is still poorly developed for coconut. Thus, there is a need to develop a new, more reliable cryopreservation protocol for this crop. A new cryopreservation protocol, based on a rapid tissue desiccation step was developed to produce a high plant recovery rate after cryopreservation. Embryos from four coconut cultivars (Malayan Yellow Dwarf - MYD, Nias Yellow Dwarf - NYD, Nias Green Dwarf and Sagerat Orange Dwarf) were rapidly desiccated for 8 hours (water content de...
The Planter
For oil palms established in deep peat soils in the Labuhan Batu district, North Sumatra, Ganoder... more For oil palms established in deep peat soils in the Labuhan Batu district, North Sumatra, Ganoderma basal stem rot (BSR) and lower frond desiccation (LFD) are the two main maladies that have a serious impact on their long-term sustainability. Past experiences have shown that solitary control measures are unlikely to be successful in managing these two maladies and a number of integrated control strategies would be a prerequisite for their management. As nutrition is an important factor influencing fungal disease infection in many crops, nutrient manipulation can be considered as a vital component of any integrated disease management (IDM) system. This paper summarises the impact of fertiliser application on the level of BSR and LFD infection in five fertiliser trials, established in the affected areas from 1996-2021. In both trials established on first and second generation oil palms, application of nitrogen (N) and phosphorus (P) elicited a significant and linear increase in BSR in...
The Planter
The correct placement of fertilisers is critical, as losses can be very significant especially in... more The correct placement of fertilisers is critical, as losses can be very significant especially in regions of high and frequent rainfall, non-terraced slopes, sandy textured soils and peat. To maximise uptake efficiency, fertilisers should be evenly broadcast over the soil surface area that contains the highest density of feeder roots. In order to determine the latter, an investigation was undertaken to ascertain the biomass and distribution of roots of various ages of mature oil palms planted in both mineral and second generation peat soils. Results of the study indicate that if site factors are not limiting, palm age and past fertiliser placement history are two major factors influencing oil palm root development and distribution. In mature well decomposed peat, although roots could be found growing 4 m from palm bole, actual root biomass per unit volume of soil was low. Only 21 per cent of the feeder roots of 8-year-old palms were found growing outside the weeded palm circles (WPC...
ACIAR PROCEEDINGS, 2006
The coconut (Cocos nucifera) is an essential part of life and cultural identity, as a food item a... more The coconut (Cocos nucifera) is an essential part of life and cultural identity, as a food item and for its many products, in the Pacific. It played a pivotal role in the economic development of the region during colonial times, but, although there has been much research on the coconut in the Pacific, it has been somewhat neglected of late. The objectives of the Land Resources Division (LRD) of the Secretariat of the Pacific Community (SPC) are to improve nutritional security and health, and incomes, through sustainable ...
The world production of coconut (Cocos nucifera L.) is low and has not increased significantly ov... more The world production of coconut (Cocos nucifera L.) is low and has not increased significantly over the last few decades. This is mainly due to the use of unimproved varieties. In addition, coconut production has been suppressed by a number of major insect pests and devastating diseases. A solution to all of these problems is in the breeding of new high yielding varieties with genetic resistance to these pests and diseases. Unfortunately, as for many perennial crops, a coconut breeding program takes a long time to undertake and produce useful new cultivars. In addition such programs are very expensive to run, particularly with coconut which has a low multiplication index, particularly in the assisted pollination system used by most breeding programs. The slow and expensive traditional breeding programs may be improved by the use of in vitro culture methods for coconut improvement. Such methods may include in vitro techniques for the collection, short term storage of embryos from the...
Journal of Oil Palm Research, Aug 1, 2013
Planta, 2010
The present study aimed at exploring the Wdelity of coconut (Cocos nucifera L.) plants recovered ... more The present study aimed at exploring the Wdelity of coconut (Cocos nucifera L.) plants recovered from cryopreservation. Zygotic embryos from various diVerent cultivars were cryopreserved following four successive steps, namely: rapid dehydration, rapid freezing, rapid thawing and in vitro recovery followed by acclimatization. At the end of the acclimatization period, the seedlings were compared to counterparts of the same age, which were produced from non-cryopreserved embryos. Both series were submitted to morphological, cytological and molecular comparisons. No signiWcant diVerences in terms of growth rates could be
Improvements to the conventional embryo culture protocol have been initiated. These improvements,... more Improvements to the conventional embryo culture protocol have been initiated. These improvements, among several, include the use of a CO2enrichment step within a photoautotrophic culture system and the application of 100 μM of either α-naphthalene acetic acid (NAA) or indolebutyric acid (IBA) to promote rooting of seedling. To obtain uniform germination of embryos of different ages, abscisic acid (ABA) at 0.97-7.67 μM is added to the germination medium. ABA could be replaced with gibberellic acid (GA3) at 10.00 μM when handling varieties that are difficult to germinate. Following the in vitro acclimatization using the CO2 enrichment system, the hardening-off process ex vitro in the screenhouse is done by placing the seedlings inside the acclimatization box that provides high relative humidity and sufficient headspace for growth. Alternatively, a clear plastic covered tent could be used instead when dealing with large numbers of seedlings. By using this enhanced methodology on the em...
A new technique for coconut (Cocos nucifera L.) germplasm collection was evaluated in the laborat... more A new technique for coconut (Cocos nucifera L.) germplasm collection was evaluated in the laboratory and tested in the field in Indonesia. The technique involved the non-sterile isolation of embryos, and incubation in sterile ascorbic acid solution (1 mg L –1 ) at 5 1˚C in the dark. During this incubation period the embryos could be transported and/or stored for a period of up to 4 days without embryo viability loss. Following this period the embryos were surface sterilised with sodium hypochlorite (1.5% w/v) for 20 min, washed with sterile water and cultured in a liquid Y3 basal nutrient medium supplemented with Morel and Wetmore vitamins, sucrose (175 mM) and activated charcoal (2.5 g L –1 ). After two weeks the embryos were subcultured onto a solid medium of similar constitution to encourage germination. Germinated embryos grew and produced healthy plants with normal morphology. Despite mild chilling injury as indicated by elevated ethylene production and solute leakage, the transported embryos retained viability with normal morphology. Using the low-temperature incubation treatment, the microorganism density in the ascorbic acid solution was kept low while that around other embryos kept at higher temperatures (25˚C) increased. Even though embryos were exposed to a low-temperature treatment for up to 4 days they were able to germinate (95% viable) and grow in an identical fashion to freshly cultured embryos.
Cryobiology, 2010
Cryopreservation of coconut can be used as a strategy to back up the establishment of living coll... more Cryopreservation of coconut can be used as a strategy to back up the establishment of living collections which are expensive to maintain and are under constant threat from biotic and abiotic factors. Unfortunately, cryopreservation protocols still need to be developed that are capable of producing a sizeable number of field-grown plants. Therefore, we report on the development of an improved cryopreservation protocol which can be used on a wide range of coconut cultivars. The cryopreservation of zygotic embryos and their recovery to soil-growing plants was achieved through the application of four optimised steps viz.: (i) rapid dehydration; (ii) rapid cooling; (iii) rapid warming and recovery in vitro and (iv) acclimatisation and soil-supported growth. The thermal properties of water within the embryos were monitored using differential scanning calorimetry (DSC) in order to ensure that the freezable component was kept to a minimum. The feasibility of the protocol was assessed using the Malayan Yellow Dwarf (MYD) cultivar in Australia and then tested on a range of cultivars which were freshly harvested and studied in Indonesia. The most efficient protocol was one based on an 8-h rapid dehydration step followed by rapid cooling step. Best recovery percentages were obtained when a rapid warming step and an optimised in vitro culture step were used. Following this protocol, 20% (when cryopreserved 12 days after harvesting) and 40% (when cryopreserved at the time of harvest) of all MYD embryos cryopreserved could be returned to normal seedlings growing in soil. DSC showed that this protocol induced a drop in embryo fresh weight to 19% and significantly reduced the amount of water remaining that could produce ice crystals (0.1%). Of the 20 cultivars tested, 16 were found to produce between 10% and 40% normal seedlings while four cultivars generated between 0% and 10% normal seedlings after cryopreservation. This new protocol is applicable to a wide range of coconut cultivars and is useful for the routine cryopreservation of coconut genetic resources.
... substance which absorbs phenolic substances, has been used in coconut suspension cultures ...... more ... substance which absorbs phenolic substances, has been used in coconut suspension cultures ... been used in callus culture systems, and its effects on somatic embryogenesis are unknown. ... used to prevent the production of phenolic substances in date palm (Phoenix dactylifera ...
II International Symposium on Biotechnology of Tropical and Subtropical Species, 2005
Of those explants tested, immature zygotic embryo tissues proved to be the best for initiating ca... more Of those explants tested, immature zygotic embryo tissues proved to be the best for initiating callus with potential for somatic embryogenesis. Slicing of this tissue and use of the central sections (near to and including the meristematic tissue) gave the best embryogenic response. Slices that were placed under illumination necrosed more rapidly and to a greater degree than those incubated in the dark. Explant slice necrosis could be prevented or severely retarded by the addition of activated charcoal into the medium. Washing the explants for short periods of time prior to culture was also found to improve callus production. Prolonged washing resulted in low rates of callus production. In an attempt to prevent ethylene accumulation in the culture vessel headspace, AVG, an ethylene biosynthesis inhibitor and STS, a chemical which reduces the physiological action of ethylene, were successfully used to promote somatic embryogenesis. Spermidine, putrescine and spermine, polyamines that are known to delay plant senescence and promote somatic embryogenesis in some plant species, enhanced the rate of somatic embryogenesis when they were introduced into the callus induction medium. The use of polyethylene glycol in combination with abscisic acid helped promote somatic embryo formation and maturation as well as the subsequent formation of plantlets. The use of all of these improvements together has created a new and improved protocol for coconut somatic embryogenesis. This new protocol puts significant emphasis on improving the in vitro ecology of the explant, callus and somatic embryogenic tissues.
International Symposium on Tropical and Subtropical Fruits, 2002
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Papers by Yohannes Samosir