Assessing the Susceptibility and Tolerance of Oil Palm Cultivars to Leaf-Bending: A Comparative Physiological and Nutritional Balance Study

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&rsquo: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&times: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 &times: La M&eacute: and Coar&iacute: &times: La M&eacute: genetic background were the most tolerant: however, the Deli &times: AVROS and Deli &times: 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&rsquo: physiological parameters decreased between 40% and 50%. The nutritional diagnosis showed that the most sensitive cultivars to leaf-bending were Deli &times: 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 &times: La M&eacute:, which presented the lowest IBNm, associated with a better nutritional condition.