WALNUT RESEARCH IN FRANCE

Gale McGranahan

ABSTRACT

Walnut research in France is carried out by scientists employed bythe Centre Technique Interprofessionel des Fruits et Legumes (CTIFL)and the Institute National de la Recherche Agronomique (INRA). (TheAssociation Foret-Cellulose (AFOCEL) which has been active in researchon walnut propagation is terminating their walnut project this year.)CTIFL focuses on applied research and technology transfer. Muchof the work at the CTIFL research stations is aimed at adapting Ameri-can technology developed for laterally fruitful varieties to Frenchgrowing conditions with the expectation that improved laterally fruit-ful varieties will be available in the near future. Because of thevariation in soil types in France, rootstock studies at CTIFL stationsare yielding important information on rootstock adaptation to specificsoil types.

INRA is responsible for basic research, plant improvement and propaga-tion. INRA scientists will have a major impact on walnut researchin these areas. E. Germain, INRA, maintains a germplasm repositoryfor all of Europe. His main focus has been on collecting establishedvarieties and improved selections from France, U.S., and easternEurope. A summary of evaluations is included in this report. Germainscollection may be complementary to that of the National Clonal Germ-plasm Repository - Davis which will concentrate on native collections.Germain is willing to exchange materials in his germplasm col]ectionand arrangements have been made to receive selected seed and scionwood.Research on cold-hardiness and bud dormancy (J.C. Mauget, INRA) mayprovide information needed to extend the range of English Walnutsin the U.S. Work of C. Jay-Allemand and D. Cornu on markers forjuvenili ty may have an impact on propagation of walnuts and manyof the perennial crops which are difficult to initiate in culture.

OBJECTIVES

The purpose of this trip was to visit the primary walnut researchstations in France and to discuss germplasm, breeding, culture methodsand in vitro propagation of walnut with experts in the field.

PROCEDURE

Dr. E. Germain organized the itinerary for this trip. It includedvisits to walnut producing regions of France as well as to laboratoriesinvolved in tissue culture of walnuts.

RESULTS AND DISCUSSION

More walnuts aremajor productionDordogne, Lot andof Isere and Drom20 and 30 metric

produced in France than any other nut crop. Twoareas are recognized, one in the departments ofCorreze (southwest) and the other in the departments(southeast). Total annual production ranges betweentons. Walnut production is expected to increase

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in the southeast, a region known for the "Noix de Grenoble" and todecrease in areas isolated from the 2 major production regions. Severalintensively managed orchards are present in the valley of the Garonnein the southwest and this area may increase in production as well.

Two research institutions have active programs on walnuts: the CentreTechnique Interprofessionel des Fruits et Legumes (CTIFL) and theInstitute National de la Recherche Agronomique (INRA). CTIFL focuseson applied research and technology transfer. INRA is responsiblefor basic research, plant improvement and propagation. Cooperationbetween the two organizations is excellent.

The following itinerary is designed to provide information on researchstations visited, individuals contacted and a brief summary of currentresearch along with my own impressions regarding research and potentialfor collaboration.

9/15-9/17 Centre Technique Interprofessioneldes Fruits et Legumes (CTIFL)

Station Experimentale de la Noix de GrenobleChatte, 38160 St. Marcellin, France(G. Charlot)

This is the major walnut research station for the southwest of France.The region contains approximatley 8000 hectares of walnuts, 30% ofwhich were planted less than 15 years ago. Approximately 200 hectaresare planted annually0 The major varieties are Franquette (80-90%),Parisienne (10%) and Mayette (6-7%). The major rootstock is Juglansregia but 10% of the commercial plantings are J. nigra. The cherryleafroll virus is expected to decimate this population eventually.The J. regia rootstock parent trees ('Lozeronne') have also beenfound to be infected and thus the virus is widely distributed inthe region. Most of the orchards that I visited were under severestress due to the cold temperatures in 1/85 and severe drought duringthe growing season. The Swiss method of making longitudinal cutsin the trunk to avoid cold damage was successful but rarely used.

Research at the station is focused on cultural practices - irrigation,fertilization, training systems, orchard floor management and disease

.control for blight and anthracnose. In cooperation with INRA theyalso evaluate varieties and selections. Overall the research isoriented towards developing the methodology for managing new laterallyfruitful varieties when they become available. Currently, however,no variety has surpassed Franquette in overall performance. Of theAmerican varieties tested (quite a complete collection of Californiavarieties) Pedro and Hartley excelled, the former for high yields(but poor shell formation due to cool temperatures) and the latterfor nut quality. Lara, a Payne offspring selected in the southwestof France has also shown promise.

9/17-9/18 Institut National de la Recherche Agronomique (INRA)Centre de Recherches Agronomique du Massif CentralLaboratoire de BioclimatologicDomaine de Crouelle63039 Clermont-Ferrand, Cedex.

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(JoCo Mauget, Director M. Bonhomme, R. Ragneau, F.AoDaudet, P. Cruziat, A~ Lacointe, J.S. Frossard.)

Walnut, peach and apple have been chosen here as model crops forthe study of perennial crop ecophysiology. J.C0 Mauget who is wellknown for his work on dormancy and bud initiation in walnuts hasrecently added several young scientists to his team. Research atthe station now includes physiological studies on roots in relationto the whole plant, photosynthesis, water relations, dormancy andthe effect of climate on growth and development. This research stationwill probably become one of the world centers for basic physiologicalstudies of walnuts0 J0C. Mauget expects to visit Davis next yearand the potential for continued exchange of information and collabora-tion is good. '

9/18-21 Centre Technique Interprofessionneldes Fruits et Legumes (CTIFL)

Centre de Nouvert - BP7, 19360 Malemort(Y. Jestin, Me Delatre)

This is the major CTIFL research station for walnuts in the southwestof France. The region contains a variety of growing conditions forwalnuts. Approximately 50% of the trees are in orchards, the remainderare isolated trees or windbreaks. Production has been decreasingexcept in the departments of Gironde, Dordogne, Charente and Lot.The main varieties are Corne, frequently sold as "noix fraiches"or undred nuts, Marbot and Grandjean. Franquette is replacing Corneand Lara is expected to become an important variety in the future.The research station has research plots in the north of the regionnear Exideuil on rocky, calcareous soil and in the south near Cahorson a deep alluvial plain as well as on the station itself which hasshallow acid soil.

The research emphasis here is similar to that of the CTIFL stationin St.-Marcellin. Most interesting here is the work on rootstockswhich has been underway for over 20 years. As would be expected,'-'interspecific hybrid rootstock is the most vlgGrOUS and seed sourceshave been identified which hybridize readily. The hybrid betweenJ. sieboldiana (J. ailantifolia) and J. regia shows promise for soilswith a low pH. Clonal J. regia rootstock have also been evaluatedand one clone 111-19 was shown statistically to be superior in bothyield and vigor.

This station also has variety trials and tests of selections developedby E. Germain (INRA). The latter have just recently be grafted inthe crowns of mature trees but no data has been collected. Pedroand Lara have already been accepted by several growers. Both Y.Jestin and his technician Mo Delatre are enthusiastic researchersbut much of their work is aimed at adapting American culture methodsto France.

9/21-9/28 Institut National de la Recherche Agronomique (INRA)Centre de Recherches de BordeauxStation de Recherches d'Arboriculture FruitiereBP131, 33140 Pont-de-la Mave

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(E. Germain F. Dosba (Director) and others)

Pepinieres du Domaine de LalanneSt-Maixant 33490 St-Macaire(Ao Vercesi, Po Averseng)

The research station here is responsible nationally for the geneticimprovement of cultivars and rootstocks of walnut, hazelnut, chestnut,peach, plum and cherry. I spent the majority of my time with E.Germain who heads the walnut breeding program and is responsiblefor germplasm collection for all of Europe. Currently 125 clonesare maintained in the repository. The characters in relation tosource are described in Table 10 In 1977 Germain initiated a breedingprogram. Prior to this, most effort was directed towards collectingand evaluating germplasm from France, E. Europe and the U.S. Asno cultivar combined the desired traits of late leafing, lateralbearing and high quality kernels he selected combinations of parentsmost likely to have superior progeny. Of the 16 combinations hehas chosen, all but two are French type (Franquette, Soleze, Marbot,Grosvert and Rond de Montignac) crossed with American type (Payne,Ashley, Pedro, Lara, Howard and Chandler). The two remaining areAdams 10 crossed with Lara and Chandler. Adams 10 appears to haveresistance to bllght0 The preliminary goal is to obtain at least100 late leafing progeny from each combination. Only the late leafingindividuals are transplanted from the nursery to the "seedling block".Preliminary results suggest that 'Lara' is a promising parent. Ahigh percent of its progeny are late leafing and laterally fruitful.The first releases are expected from this program in 1995. Untilthen, E. Germain recommends 'Lara' to French growers. In Table. 2the germplasm which will be of interest to American breeders is listed.Arrangements have been made to introduce it to the UoS.

Because E. Germain is continually searching for newplasm and because his evaluations are thorough andimportant that we continue cooperation0 It appearson his collection as a repository of European andvarieties.

sources of germ-accurate, it isthat we can relyeastern European

9/29-10/1 Associatlon Foret-cellulose (AFOCEL)Domaine de L'Etancon77370 Nangis(D.X. Destremau, Director; A. Franclet, ScientificAdvlsor; v. Meynier, Thesis on Micropropagation ofa hybrid walnut.)

Although AFOCEL concentrates primarily on research on trees for thepulp and paper industry, since 1975 they have had a project on propaga-tion of Juglans. Airlayering of stump sprouts was found to be themost satisfactory method of conventional propagation and has beenconsidered economically feasible if clones are first selected forrootabilityo Rejuvenation through repeated pruning is required beforethe method can be used for mature material.

In vitro propagation has alsobeen successful in introducing

been investigated.one J. nigra x J.

V. Neynierregia clone

,hasinto

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culture using meristem-tip culture. The cultures did not look vigor-ous. The major problem encountered was contamination and in coopera-tion with microbiologists Meynier has been able to identify severalgenera of bacteria that may be internal in Juglans.. Her thesis shouldbe available in several months. Currently, there are no plans tocontinue work with Juglans at this station, however, D. Destremauexpressed considerable interest in walnut wingnut hybrid developedin my laboratory.

10/1-10/2 Institut National de la Recherche Agronomique (INRA)Centre de Recherches d'OrleansStation d'Amelioration des Arbres ForestiersArdon. 45160 - Olivet(D. Cornu)

D. Cornu is responsible for research on propagation of a number offorest tree species. A graduate sutdent C. Jay-Allemand has beeninvestigating walnut rejuvenation and micropropagation since 1981.The cultures I observed were healthy and moderately vigorous. Thepreferred media was DKW. These researchers have found that a twoweek period in July is the only time explants calf be successfullyinitiated into culture. The PhD thesis of Jay-Allemand (which wasstill in draft stage) is focused on detecting markers for juvenilityin Juglans. This is work that has been sorely needed in Juglansand other woody species. The thesis should be available shortly.

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TABLE 1.

Characteristics as a function of origin according to E. Germain.

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French Calif. Oregon Europe

Vigor Good Mod. weak Very Good Good

Habit Upright Spreading Upright UprightColdHardiness Good Poor Very Good Very Good

Leafing out Late Early Early EarlyHarvest Late Early Intermed. EarlyPrecocity Slow Rapid Mod. Rapid Slow

Productivity Mod. Very Good Good Mod.-Poor

Nut Quality Very Good Mod. Good Good Poor

Seal Good Poor Good Poor

Strength Good Poor Good PoorSize Intermed. Good Good

Kernal Quality Good-Very Good Mod. PoorGood

% Kernal <50% >50% >50% >50%

Bestvarieties Franquette Lara Chase 09 Sibisel 39

Marbot Hartley Adams 10 Geisenheim 139Parisienne Howard

Grandjean ChandlerGrosvert

TABLE2.

GermplasmRecommended For Introduction Into U.S.

FR

FRFRFRFR

ImprovementLara. Lateral bearing, late leafing, potential

varietyVerdot (Grosvert). Cluster typeSoleze. Progeny late leafingRonde de Montignac. Precocious & abundant

pollen producer

Meylanaise. Extended pollen shedding period

Chase D9. Blight resistant, may be obtainedfrom Oregon

Adams 10. Blight Resistant, may be obtainedfrom Oregon

Sibisel 39. "Best of E. Europe varieties"Geisenheim 139. "Best of E. Europe varieties".

red kerna1 cultivar

Improvement

Lozeronne. Uniform progeny. Best of FR.rootstocks

RA 611. 20% of progeny unusually vigorousRA 882. Vigorous progeny

Culplat. Good for high pH loco (Texas?)

Corne. Vigorous

Naturally produceNaturally produce

Naturally produce

Naturally produce

Cultivar

~ regia

~ regia~ regia~ regia

~ regiaJ. regia

J. regia

J.J.J.

regiaregiaPurpurea

Rootstock

J. regia*

J.J.J.J.J.J.J.J.

regia*regia*regia*regia*hindsiisieboldiana

nigramajor?

*seed requested

high %high %high %high %

hybridhybridhybridhybrid

progenyprogenyprogenyprogeny

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FR

FRFRFR

FRUS

US

E. Eu.E. Eu.FR