February, 2012 CAS Meeting Developing new varieties The challenge for present/future avocado growers Greater cultural, harvesting and water costs coupled with increasing market competition Enhancing Productivity/Fruit Quality Understanding tree physiology and stress responses High density plantings Reducing Alternate Bearing Improve nutritional and postharvest quality Mary Lu Arpaia Eric Focht, Margy Crowley University of California, Riverside Achieve this goal Rootstocks for disease, salinity tolerance, dwarfing Varieties w/ > productivity, pest tolerance, suitable for close spacings and higher postharvest quality Pollinizers and Pollinators We need to go from Here We need to improve postharvest quality and enhance eating/nutritional quality There To stay competitive 1
Even though Hass was discovered in the early 1930 s and patented by Rudolph Hass in 1935, it was not until large-scale industry expansion occurred 40 years later (in the late 1970 s) that Hass replaced Fuerte as the leading California variety. Rudolph and Elizabeth Hass Hass History: Guatemalan seedling planted in La Habra Heights in 1926. Patented in 1935. Seasonality in La Habra Heights: Patent: May - September CAS 1945 Yrbk: May October There is a growing group within the California Avocado industry who believe that the Hass avocado is now our number two variety and that in tonnage it is destined to eventually exceed all other varieties excepting only the Fuerte. This group points out that the Hass season compliments the Fuerte season making possible a two variety coverage of the year as in the orange industry. (Griswold, 1945) From: California Avocado Society 1945 Yearbook 30 The Hass Avocado H. B. Griswold From the market standpoint the Hass would appear to have everything. Excellent quality, popular size, small seed, good shipper, its leathery skin and long season complimenting the Fuerte. Its single disadvantage is its black color which has been associated in the minds of the public with poor quality fruits. Experience is indicating however that when properly handled this color handicap can be overcome. The Hass variety gives satisfaction and repeat business follows. Our leading cultivar, Hass CAN BE improved: Fruit size Postharvest quality Tree size and structure Bearing habit Alternate bearing Cold tolerance Insect tolerance Salinity tolerance Productivity Seasonality We have the potential to improve It is dangerous to have an industry based on one variety 2
Scion Breeding: Avocados were introduced to California at the turn of the last century. The hunt for improved varieties has continued ever since. By the 1950 s around 25 different varieties of avocados were being commercially packed and shipped in California, with Fuerte accounting for more than two-thirds of the production. The first controlled breeding in California: 1937 by J. W. Lesley at UC Riverside, and 1939 by W.E. Lammerts at UCLA. He was followed by R. Bringhurst. Bob Bergh took over the UC Riverside breeding program in 1956, retiring in 1992. Program Goals Diversify with superior selections To develop new varieties for CA Emphasis on Hass -like selections Fruit Quality: equal or superior to Hass New Pollinizers Seasonality Short term: augment Hass season Long term: replace Hass Cropping: reduced alternate bearing Cultural management Growth habit conducive to High Density Adaptability to varied environments Salinity/drought tolerant Pest management Tier 1 Flavor Components of evaluation Fruit characteristics size, seed size etc. Tier 2 Yield and maturity Postharvest quality and consumer panels Tree vigor growth habit Flowering Behavior Tier 3 Components of evaluation Establish evaluation plots in San Diego, Orange, Ventura, Tulare counties Yield Maturity, postharvest quality and consumer panels Tree vigor growth habit Flowering, stress tolerance Tier 4 Commercial release of superior material 3
Timeline - 1982 to present 1982 release of Gwen, Whitsell and Esther Mid-1980 s; planting of 50,000+ seedlings in various locations 1992 Bergh retires; Witney assumes responsibility with G. Martin as field person 1996 Lamb Hass and SirPrize released 1996 Witney resigns, Arpaia assumes responsibility 1997 G. Martin resigns 1999 Reorganization of project, planting of first seedlings since mid 1980 s 2003 3-29-5 (GEM) and N4 (-5) (Harvest) released Differences between Hass and Lamb Hass Lamb Hass maturity season mid to late summer NOT A SUBSTITUTE BUT SUPPLEMENT TO HASS Fruit shape and size more square but larger Lamb Hass has more upright growth habit Flexible wood fruit borne interior of tree; tends to set fruit in clusters Lamb Hass is more tolerant to Persea mite and other pests (?) Photosynthetic rate approximately 30% higher than Hass and higher chlorophyll content 4
Fruit Maturity Lamb Hass Growth habit differences between Hass and Lamb Hass 40 36 % Dry Weight Hass '99 Hass '00 Hass '01 Lamb '99 Lamb '00 Lamb '01 32 28 24 20 16 Jan 1 Jan 29 Feb 26 Mar 26 Apr 23 May 21 Jun 18 Jul 16 Aug 13 Sep 10 1)Trends consistent over years 2)Dry matter accumulation lags behind Hass Hass Lamb Hass Differences between Hass and GEM Maturity seasons overlap; GEM slightly later COULD BE A SUBSTITUTE TO HASS Can accumulate very high levels of dry matter Fruit shape more tear drop GEM growth habit more vaselike and compact Flexible wood fruit borne interior of tree; tends to set fruit in clusters Pest tolerance (?) 5
Fruit Maturity - GEM 34 GEM Hass Dry Matter Content (%) 32 30 28 26 24 1/2 1/16 1/30 2/13 2/27 3/13 3/27 4/10 4/24 5/8 5/22 6/5 6/19 7/3 7/17 7/31 8/14 8/28 9/11 9/25 10/9 2002 Similar pattern of dry matter accumulation to Hass; tends to be slightly later Gem is a more compact tree than Hass, very similar to Gwen Bears fruit on the inside of the tree Comparative Trials 6
Yield UC South Coast REC trial KG/TREE (1999-2005) Alternate bearing is lowest in GEM The lower the number the less alternate bearing 400 350 GEM 300 250 Yield (kg/tree) 200 150 2005 2004 2003 2002 2001 2000 1999 BL516 BL667 Lamb Hass 100 Hass 50 Harvest 0 BL516 BL667 Hass Lamb Hass Harvest GEM Fruit size also collected. Gem tends to be slightly larger than Hass but smaller than Lamb Hass. Seed size is slightly larger than Hass. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Alternate Bearing Index Post Lamb Hass and GEM What Progress have we made? 465418-99 Planted 2007 on Duke 7 Have made 16 selections that have gone into second tier evaluation (1.9% selection rate) Planted first Tier 3 plantings in April 2011 in San Diego, Orange, Ventura and Tulare Counties 7
465518-99 Planted 2007 on Duke 7 464918-99 Planted 2008 on Duke 7 465202-99 Planted 2008 on Duke 7 467352-00 Planted 2007 on Duke 7 8
465006-99 Planted 2008 on Duke 7 SCION:ROOTSTOCK INTERACTIONS Purpose: To demonstrate rootstock effect on several horticultural traits including yield, fruit size, alternate bearing, tree size and tree nutrition Trial Planted June 2012 Ventura County 5 Varieties: Hass, Carmen Mendez, Lamb Hass, GEM, Reed 9 Rootstocks: Dusa, Duke7, RO.O6, Zentmyer, Uzi, Steddom, Brandon, Eddie, Anita The Importance of the Germplasm Collection Preservation of older varieties from the CA and elsewhere Largest collection of varieties focused on MX-Guat races Home to interesting materials that may one day be useful for future breeding Public Education Molecular Genetics and New Varieties Avocado Genome soon to be completed (L. Herrera group) SNP Chip available to map 6000 markers Will allow us to pursue Marker Assisted Breeding to increase efficiency of program Will use this approach to select for Fruit quality Fruit nutrition Tree architecture Alternate bearing 9