Development and Commercialization of Improved New Disease Resistant Scions and Rootstocks – the Key For a Sustainable and Profitable Florida Citrus Industry

Development and Commercialization of Improved New Disease Resistant Scions and Rootstocks - the Key For a Sustainable and Profitable Florida Citrus Industry

Report Date: 05/24/2016
Project: 15-010   Year: 2016
Category: Plant Improvement
Author: fred Gmitter
Sponsor: Citrus Research and Development Foundation

Our project is focused on the following objectives: 1. Development of rootstocks that can impart HLB tolerance/resistance to grafted scions. 2. Breeding of HLB tolerant/resistant processing sweet orange-like hybrids. 3. Screening of the UF-CREC germplasm collection to identify and validate HLB tolerant or resistant selections. 4. Advanced field trials, release and commercialization of promising HLB tolerant/resistant scion and rootstock cultivars. The project began on 1 November 2015. In the late autumn, and through the winter and spring, we collected data from several ongoing field trials of rootstock cultivars throughout the state. Trees were assessed for HLB incidence and severity through all plantings, and yields and fruit quality was determined in selected replicated trials. Hybrid families planted in the field were evaluated to identify selections producing fruit that resembled sweet orange in appearance, and exhibiting few or no HLB symptoms. Fruit from the best of these were tested for juice quality and a few were also analyzed for volatile components and compared with standard sweet orange. Fruit samples were provided to a major juice company for processing and assessment of the juice for flavor. The entire collection of raw material produced by the breeding program and growing in groves at several different locations throughout the growing areas of Florida has been assessed for HLB symptoms, to identify individuals displaying few or no symptoms of HLB, regardless of parentage; ~4.3% of all trees were characterized as tolerant based on tree health and overall appearance. Specific highlights in the reporting period are below. � The GFC/Indiantown project has been terminated and removed. A narrative with figures will be prepared on posted on the CREC website under Varieties and Rootstocks. � Yield data and HLB ratings were obtained from the Wheeler multi-scion/rootstock cooperative trial. Difference among rootstocks and scion-rootstock interactions were apparent even among these 3 year old trees. � Yield data were obtained from 3 year old trees on various rootstocks planted 8 x 15 in a CPI cooperative project. � The CREC plant breeding team�s collective field evaluation records have been reviewed, consolidated and organized for more efficient record keeping. � A 3.5 year old planting of 220 OLL seedlings was assessed for HLB; two HLB-free seedling trees were identified and propagated for further study. � 2016 crosses included several crosses of HLB-tolerant mandarins with sweet orange-like juice profiles with OLL oranges in efforts to develop seedless HLB-tolerant sweet orange-like hybrids for processing and fresh market. � 2016 rootstock crosses (diploid and tetraploid) featured HLB tolerant parents, and included crosses of LB8-9 with Phytophthora resistant parents. � Two more sets of gauntlet rootstocks were rotated into a �hot psyllid� house, approximately 100 trees were prepared for field planting (this quarter). � Gauntlet trees at Picos Farm were assessed; 10 selections 3-4 years old are promising and being further monitored. � Yield and fruit quality data were collected again from 6 and 7.5 year old trees in the St. Helena Project. A public Field Day was held to update interested growers on progress with the trial and selected UFRs.

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