Citrus Huanglongbing Impact on Citrus Trees Biomass and Nutrients Uptake.

Understanding the effect of Huanglongbing (HLB) in citrus groves are critical in determining crop nutrients management practices. The experimental evidence on the role of citrus Huanglongbing in nutrients uptake and tree biomass of infected HLB in southwest Florida groves are lacking. Thus, the objective of this study was to determine citrus trees biomass and nutrients uptake by HLB and non-HLB trees of two orange (Citrus x sinensis (L.) Osbeck)  cultivars (Hamlin and Valencia). The study was initiated in January, 2014 on a fine sand soil texture (Sandy, siliceous, hyberthermic Arenic Alaquods). Twenty-four soil lysimeters were used, twelve trees of each cultivar including infected and non-infected trees. A mixed blend (20-2-20) fertilizer with a total yearly rate equivalent to 329, 33, and 329 g N, P, and K was applied per tree. Leaves were sampled for nutrient analysis during the growing season, however, at the end of the study entire trees were sampled by dividing them into three portions including leaves, shoots, and roots. Total nitrogen concentration was determined on finely ground oven-dried samples via dry combustion. Total P, K, Ca, Mg, Fe, Mn, Zn, Cu and B concentrations were determined simultaneously by Inductively Coupled Plasma (ICP). Results showed significant variation in tree biomass and nutrient uptake under HLB and non-HLB affected trees. Biomass partitioning of HLB affected trees represented 27% and 62%, 38% and 27%, 26% and 14% of dry leaf, shoots, and roots of non-HLB affected Valencia and Hamlin trees, respectively.