Evaluation of citrus rootstock response to HLB in large-scale existing field trials

Evaluation of citrus rootstock response to HLB in large-scale existing field trials

Report Date: 01/31/2022
Project: 18-029C   Year: 2021
Category: Plant Improvement
Author: Ute Albrecht
Sponsor: Citrus Research and Development Foundation

 This project addressed CPDC priority 3A. “Collect standardized data on existing field trials to evaluate citrus scion and rootstock response to HLB”. The purpose of the project was to conduct evaluations of rootstocks in existing replicated field trials regarding their horticultural performance and ability to mitigate HLB-induced decline. The cooperative trials were planted in 2015 and contain more than 20,000 Valencia and Hamlin trees on more than 30 different replicated rootstock cultivars and other non-replicated ones. Trials were under commercial management (Lykes Bros.) and planted near Basinger (Highlands County) and Lake Wales (Polk County). For annual evaluations, only replicated rootstocks were included using 6 replications. The complete set of rootstocks was included in year 3 evaluations. The rootstocks included UF/IFAS (CREC) released and experimental selections, California selections (available in FL), and selections from Spain. The Spanish selections are proprietary and not available for use in the USA currently but may be available soon. The UF selections are tetraploid cultivars, meaning that they were created by somatic hybridization or from crosses at the tetraploid level. All other rootstocks were diploids and created by sexual hybridization.All replicated rootstocks were evaluated annually using the methods established in the Denver protocol and outlined in the proposal (also see appendix). Data collected include tree size (height, canopy volume, trunk diameter), fruit yield, fruit quality (total soluble sugars, acid, brix/acid ratio, etc.), leaf nutrients, canopy health (canopy color, canopy density, foliar HLB disease symptoms), and wind resistance/tree leaning (after hurricane Irma). A comprehensive data was assembled for each scion/rootstock combination and trial location and is attached to this report as 4 Excel files: 1) Albrecht_18-029C_VAL_Replicated_Yrs1-3.xlsx; 2) Albrecht_18-029C_VAL_All_Yr3.xlsx; 3) Albrecht_18-029C_HAM_Replicated_Yrs1-3.xlsx; 4)         Albrecht_18-029C_HAM_All_Yr3.xlsx. 


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