Coconut (Cocos nucifera L.) is an important palm species that serves as the mainstay of several industries and contributes to the livelihoods of millions of smallholder farmers. International exchange of coconut germplasm has been undertaken for several decades to facilitate the conservation of selected varieties within global genebanks and for the distribution to farmers and scientists. In vitro systems are a convenient and an efficient method for the exchange of coconut germplasm. However, it is possible that these tissue culture systems can transfer lethal pathogens causing a threat to the importing countries. In this review, the following topics are discussed: the major disease-causing agents of concern, the various tissues that could be used for coconut germplasm exchange, and the techniques available for the detection and elimination of disease-causing agents from various transmission systems. Additionally, the lack of clear, science-backed guidelines to facilitate the exchange of in vitro coconut materials is raised, along with recommendations for future studies to ensure the safe movement of coconut germplasm without biosecurity risks.

As one of the most important members of the palm family, coconut (Cocos nucifera L.) currently faces a substantial gap between demand and production. Current plantings of this crop are aging, and these traditional varieties are susceptible to several devastating pests and diseases. Consequently, there is an urgent need to replant and expand coconut lands with new, genetically superior varieties. Such replanting cannot be met through the conventional method of seed nut planting, and tissue culture has emerged as a likely solution to address this problem. However, due to certain technical barriers, elevated costs, and a need for improved efficiency, the development of automated and highly efficient tissue culture techniques is yet to be developed. The present research explores the potential of an in vitro temporary immersion system (TIS) to improve the production of somatic embryogenic callus for plantlet regeneration. Results indicated that, in comparison to the conventional agar-based method used to produce coconut somatic embryogenic callus, the TIS method significantly enhanced embryogenic callus production. The optimal biomass of callus for inoculating the TIS was determined to be 0.2 g in each 900 mL vessel and the most favorable embryogenic developmental stage for employing TIS was the globular stage of embryo development. The most effective immersion time to give the highest yield of embryogenic callus was 5 min every 6 h. This foundational research demonstrates that a TIS step is likely to be important to rapidly produce, on a large scale, coconut plantlets to meet the escalating demand for materials for the replanting of coconut lands.

The coconut (Cocos nucifera L.), a valuable tropical crop, is rapidly declining in genetic diversity due to natural disasters, pest and disease attack, and land clearing for other crops. Seed banking is impractical for coconut conservation due to its large, recalcitrant seed, and maintaining field gene bank collections is costly and vulnerable to environmental pressures. Cryopreservation offers a promising alternative method for conserving coconut genetic diversity, but the success in recovering cryopreserved materials remains limited, with few studies consistently reporting high rates of recovery. This highlights the need for improved cryopreservation protocols, particularly in tissue dehydration, which is one of the critical steps in the process of cryopreservation and plant recovery. A desiccator was developed that enabled rapid embryo dehydration with ultra-dry airflow. The desiccator reduced embryo moisture content to 20% (the predetermined viability threshold) within 6 h representing a 2-h improvement when compared to a previous dehydration approach, while maintaining a high germination rate (71%). Smaller embryos (500 to 550 mg fresh weight) desiccated faster than larger embryos (800 to 900 mg fresh weight) but germination was reduced (30%), making small embryos unsuitable for cryopreservation. A 5-day sucrose (0.4 M) pre-treatment further reduced the dehydration time to 4 h, while maintaining a high germination rate (70%). These advances in the use of a sucrose pre-treatment, the rapid embryo dehydration, and selection of large embryos size will help to enhance the success of coconut embryo cryopreservation and recovery.

Coconut (Cocos nucifera L.) is an important tropical palm globally, but due to declining production, it is failing to meet the rapidly increasing market demand. In vitro technologies, including embryo culture, cryopreservation, and clonal propagation, are being explored to increase productivity and to conserve unique varieties. Despite the development of these technologies, there is still a need to improve the acclimatization process used to produce the large numbers of high-quality coconut seedlings needed for planting. Enhancing seedling growth and development during acclimatization, using an elevated concentration of atmospheric carbon dioxide (CO₂), and applying appropriate modifications to the light environment were the objectives of this study. A series of four semi-automated acclimatization chambers, which could control atmospheric CO₂ concentration, relative humidity and temperature, and light intensity, quality, and photoperiod, were designed to undertake this study. An initial experiment demonstrated that a concentration of 1600 μmol mol⁻¹ CO₂ in combination with an elevated light intensity of 600 μmol m⁻² s⁻¹ could significantly enhance the growth and development of seedlings as compared to ambient CO₂ concentrations and standard illumination conditions. Further experimentation demonstrated that continuous illumination with a combination of red and blue light (7:3) gave superior growth and development. This study found that the 6-month-old age is the ideal age for accelerating the acclimatization process using CO₂. Overall, the maximum effectiveness of the photomixotrophic growth system was seen when CO₂ (1600 μmol mol⁻¹) was applied to 6- to 7-month-old seedlings under a constant (24/0 h photoperiod) but elevated light intensity (600 μmol m⁻² s⁻¹) of red and blue light in the ratio of 7:3.