Oil palm (Elaeis guineensis Jacq.) is a highly productive crop economically significant for food, cosmetics, and biofuels. Abiotic stresses such as low water availability, salt accumulation, and high temperatures severely impact oil palm growth, physiology, and yield by restricting water flux among soil, plants, and the environment. While drought stress’s physiological and biochemical effects on oil palm have been extensively studied, the molecular mechanisms underlying drought stress tolerance remain unclear. Under water deficit conditions, this study investigates two commercial E. guineensis cultivars, IRHO 7001 and IRHO 2501. Water deficit adversely affected the physiology of both cultivars, with IRHO 2501 being more severely impacted. After several days of water deficit, there was a 40% reduction in photosynthetic rate (A) for IRHO 7001 and a 58% decrease in IRHO 2501. Further into the drought conditions, there was a 75% reduction in A for IRHO 7001 and a 91% drop in IRHO 2501. Both cultivars reacted to the drought stress conditions by closing stomata and reducing the transpiration rate. Despite these differences, no significant variations were observed between the cultivars in stomatal conductance, transpiration, or instantaneous leaf-level water use efficiency. This indicates that IRHO 7001 is more tolerant to drought stress than IRHO 2501. A differential gene expression and network analysis was conducted to elucidate the differential responses of the cultivars. The DESeq2 algorithm identified 502 differentially expressed genes (DEGs). The gene coexpression network for IRHO 7001 comprised 274 DEGs and 46 predicted HUB genes, whereas IRHO 2501’s network included 249 DEGs and 3 HUB genes. RT-qPCR validation of 15 DEGs confirmed the RNA-Seq data. The transcriptomic profiles and gene coexpression network analysis revealed a set of DEGs and HUB genes associated with regulatory and transcriptional functions. Notably, the zinc finger protein ZAT11 and linoleate 13S-lipoxygenase 2-1 (LOX2.1) were overexpressed in IRHO 2501 but under-expressed in IRHO 7001. Additionally, phytohormone crosstalk was identified as a central component in the response and adaptation of oil palm to drought stress.

Water deficiency and potential drought periods could be important ecological factors influencing cultivation areas and productivity once different crops are established. The principal supply of vegetable oil for oil crops is oil palm, and new challenges are emerging in the face of climatic changes. This study investigated the photosynthetic performance of 12 genotypes of Elaeis exposed to drought stress under controlled conditions. The assay included genotypes of Elaeis guineensis, Elaeis oleifera, and the interspecific O×G hybrid (E. oleifera × E. guineensis). The principal results showed that the E. guineensis genotype was the most efficient at achieving photosynthesis under drought stress conditions, followed by the hybrid and E. oleifera genotypes. The physiological parameters showed good prospects for vegetal breeding with different O×G hybrids, mainly because of their ability to maintain the equilibrium between CO₂ assimilation and stomatal aperture. We validated 11 genes associated with drought tolerance, but no differences were detected. These results indicate that no allelic variants were represented in the RNA during sampling for the validated genotypes. In conclusion, this study helps to define genotypes that can be used as parental lines for oil palm improvement. The gas exchange data showed that drought stress tolerance could define guidelines to incorporate the available genetic resources in breeding programs across the early selection in nursery stages.

Elaeis oleifera and Elaeis guineensis, two oil palm species capable of intercrossing to produce interspecific Elaeis oleifera × Elaeis guineensis (O × G) hybrids, exhibit genetic variability in key agronomic traits such as fruit development, oil accumulation, and bunch composition. This variability influences the productivity and oil quality of the resulting hybrids. Harvesting, a critical practice in oil palm production, significantly impacts oil yield and quality. Therefore, this study aimed to ascertain the optimum harvest point (OHP) in widely cultivated O × G hybrids and its correlation with genetic backgrounds. The O × G cultivars, “Coari × La Mé” (C × LM), “Manaos × Compacta” (M × C), and “Brazil × Djongo” (B × DJ), were examined to identify notable changes during various phenological stages of bunch ripening using the O × G BBCH scale, a standardized system for describing plant growth stages based on phenological development. The research was conducted in the Southwest Colombian oil palm zone during dry and rainy seasons. Observations revealed distinctive fruit coloration patterns and increased bunch weights throughout the maturation process. However, final fruit coloration did not consistently align with maximum oil rates, indicating it as an unsuitable descriptor for OHP. The C × LM cultivar exhibited the shortest ripening period (173 days after anthesis, DAA), while M × C showed the longest at 207 DAA, followed by B × DJ at 187 DAA. Pollination efficiency varied among cultivars, with C × LM and M × C displaying higher proportions of parthenocarpic fruits. Findings suggest harvesting can occur for all cultivars between phenological stages 807 and 809—corresponding to late maturity stages in fruit development—regardless of the time of year, when maximum oil per bunch is attained. Fruit opacity, fruit cracking, and fruit detachment at stages 807 and 809 were identified as pivotal descriptors for determining the right OHP, albeit unique to each cultivar. Implementing two of these three descriptors by field workers will likely result in the highest oil yields for O × G cultivars. In conclusion, this research provides valuable insights into optimizing oil palm harvest practices, emphasizing the importance of considering genetic variability and phenological indicators for determining the optimum harvest point in interspecific O × G hybrids.

Selecting the best oil palm cultivars adapted to specific agro-climatic conditions helps ensure fruit and oil production success. Many biotic and abiotic problems can limit the productivity of the crop, some of which have not yet been described, as well as their symptoms and degree of impact. In oil palm, a disturbance known as leaf-bending occurs, in which the palms present a bending or breakage of the petiole in the leaves, representing a significant challenge for oil palm cultivation. Although leaf-bending in oil palm plantations is known, its effect on the palm’s performance and its possible causes are unknown. Thus, the objectives of the present work were to describe and propose a quantitative way to evaluate leaf-bending in different cultivars (Elaeis guineensis Jacq. and the interspecific O×G hybrid) and to evaluate the disturbance effect on the physiology and nutritional balance of the oil palm. The results showed that most leaves from leaf rings three and four of the palm phyllotaxis have the highest affectation, with 74% leaf-bending. The cultivars with a Deli × La Mé and Coarí × La Mé genetic background were the most tolerant; however, the Deli × AVROS and Deli × Yangambi genetic crosses were the most susceptible. The difference in the affectation between the groups was 60% to 70%. Leaf-bending affected physiological parameters such as photosynthesis, transpiration, and stomatal conductance. Thus, below the second ring of leaves, the affected plants’ physiological parameters decreased between 40% and 50%. The nutritional diagnosis showed that the most sensitive cultivars to leaf-bending were Deli × AVROS, which presented the highest average index of nutritional balance (IBNm), indicating that this genetic cross had the highest nutritional imbalance. On the contrary, the most tolerant cultivars were Deli × La Mé, which presented the lowest IBNm, associated with a better nutritional condition.