Investigating flower bud hardiness of new tree fruit cultivars. Other funding sources: None

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1 FINAL PROJECT REPORT Prject Title: Investigating flwer bud hardiness f new tree fruit cultivars PI: Matthew Whiting Organizatin: WSU-Prsser Telephne: mdwhiting@wsu.edu City: Prsser State/Zip: WA Cperatrs: David Ophardt, Markus Keller, Lynn Mills Other funding surces: Nne Ttal Prject Funding: Budget Histry: Item Year 1: 2009 Year 2: Year 3: Salaries $12,479 Benefits $10,358 Wages Benefits Equipment $12,163 Supplies Travel Miscellaneus Ttal $35,000 Ftntes: salaries include an Assciate in Research (@ 42% FTE plus benefits at 83%) respnsible fr regin-wide prgram crdinatin, bud cllectin, data cllectin and analyses, develpment f extensin material, and equipment maintenance and versight. Equipment includes a Tenney T2 temperature test chamber with installed humidity cntrl, datalgger, thermelectric mdules and a cmputer.

2 OBJECTIVES: The bjectives f this research prject directly address the secnd highest rated research pririty f the cherry industry 1, bud hardiness. 1. Establish new fruit bud hardiness standards by phentyping several gentypes thrughut the drmant seasn and anthesis 2. Partner with DAS t disseminate bud hardiness data t industry as rapidly and cnveniently as pssible 3. Develp preliminary data and framewrk fr pursuing federally-cmpetitive funding fr further research & utreach SIGNIFICANT FINDINGS: differential thermal analysis (DTA) is an effective methd fr determining drmant cherry and apple bud hardiness cherry and apple cultivars exhibit significant variability in hardiness DTA is nt effective when buds lse hardiness in mid-march we can duble the capacity fr DTA in the freezer frm 35 plates t 70 plates there is tremendus variability ( 20 F) in hardiness amng buds n a tree/limb/spur Delicius and Glden Delicius were advanced in flwering cmpared t Gala and Fuji Bing, Chelan, and Sweetheart were similar in flwering and advanced cmpared t Bentn Overall, Sweetheart was the least hardy cultivar and Bentn was the mst hardy Fuji was verall the least hardy cultivar and Gala was the mst hardy Hardiness is gained and lst during blm, depending upn temperature RESULTS AND DISCUSSION: We have cnfirmed the effectiveness f differential thermal analysis fr assessing apple and cherry bud hardiness, using ur newly setup freezer system. Clearly discernible high and lw temperature extherms are bservable (data nt shwn) and up t 5 drmant buds can be measured per analysis plate. With mdificatin hwever we were able t duble the capacity f the freezer and utilize up t 70 plates. This will allw greater replicatin and the ability t cmpare mre cultivars at nce, up t ca. 350 buds per freezer run. The extherm data can be analyzed and presented as LT 10, LT 50, and LT 90 readily (Fig. 1). Frm discussins with grwers it is clear that LT 10 is the mst relevant data fr frst prtectin decisin-making. We psted n ur website the up t date LT 10 under the what s new sectin. We have identified significant differences amng cherry cultivars in their minimum hardiness level (Fig. 2). It appears, frm ur preliminary analyses, that Chelan is hardier than ther test cultivars and that Sweetheart is the least hardy. There is abut a 12 F (6.5 C) difference amng the cultivars tested in their LT 50 (Fig. 2). These relative differences did nt persist during budbreak and flwering hwever. 1 Cherry Industry Pririty Setting Sessin, Prsser, WA, 19 August, 2008

3 % Kill /19/08 1/29/09 2/06/09 2/19/09 2/27/09 Figure 1. Variability in Chelan fruit bud hardiness ver time. Each data pint is a recrded lw temperature extherm. Arrw indicates LT 50 n 12 Dec Temperature Interestingly, we bserved significant variability in hardiness f individual buds within a tree. This hardiness range was as high as 18 F (10 C) between the temperature which killed the least hardy flwer t the temperature which killed the hardiest flwer. Amng flwers within a single bud hwever, there is very little variability in hardiness (i.e., all flwers are killed at a similar temperature, ±0.2 F). This phentypic diversity in hardiness within a tree/limb/spur is an issue we intend t pursue further. % Kill Bentn Bing Chelan Sweetheart Rainier Skeena Figure 2. Cmparisn f fruit bud hardiness amng sweet cherry cultivars. Hardiness was assessed n 29 Jan Each data pint is a recrded lw temperature extherm. Arrw indicates LT 50 f Chelan Temperature (C) Temperature (F) Figure 3. Cmparisn f LT 10 f fruit bud and pistils amng sweet cherry cultivars. Data prir t 26 March are lw temperature extherms. Data after 26 March are bservatinal fr pistil death.

4 Figure 4. Cmparisn f fruit bud/flwer develpment amng sweet cherry cultivars. Temperature (F) Figure 5. Cmparisn f LT 10 f fruit bud and pistils amng apple cultivars. Data are bservatinal fr pistil death. We recrded subtle variability amng apple cultivars in their hardiness prir t blm (Fig. 5). Differences became apparent in mid-april with Fuji lsing hardiness rapidly cmpared t ther cultivars. Interestingly, the warm weather in mid-april caused a lss f hardiness fr Delicius and Glden Delicius but nt fr Fuji and Gala.

5 EXECUTIVE SUMMARY This prject has dcumented the hardiness f drmant buds f ecnmically imprtant apple and cherry cultivars. We have built and utilized a system fr determining drmant tissue hardiness by differential thermal analysis. We have dcumented variability in minimal hardiness level amng cherry cultivars with Chelan exhibiting the greatest hardiness and Sweetheart the least. We have identified a range in bud hardiness f ca. 18 F amng buds sampled n the same date. The next steps fr this research are t 1) mdel blm develpment with apprpriate envirnmental data, 2) relate stage f blm develpment with susceptibility t cld damage, 3) better understand factrs accunting fr the variability in hardiness amng bus/flwers, and 4) disseminate hardiness data effectively.