Search Results

You are looking at 1 - 10 of 154 items for :

  • " Juglans regia " x
  • Refine by Access: All x
Clear All
Free access

Cevriye Mert

Juglans regia L. is typical of Juglandaceae in that it is monoecious, wind-pollinated, and self-compatible. Despite its self-compatibility, breeding and research programs have encountered difficulties acquiring sufficient quantities of pollen

Free access

Kourosh Vahdati, Naser Lotfi, Bahman Kholdebarin, Darab Hassani, Reza Amiri, Mohammad Reza Mozaffari, and Charles Leslie

seed or by grafting on rootstocks ( Vahdati, 2003 ). Hence, there is huge genetic diversity among rootstock traits. For example, there are many old Persian walnut ( Juglans regia L.) trees in Iran that have been planted on the banks of rivers. The long

Full access

Javiera Morales, Ximena Besoain, Italo F. Cuneo, Alejandra Larach, Laureano Alvarado, Alejandro Cáceres-Mella, and Sebastian Saa

). The high N inputs used in walnut production ( Gupta et al., 2012 ; Simorte et al., 2001 ; Weinbaum and Van Kessel, 1998) and the high susceptibility to P. cinnamomi reported in Juglans regia L. ( Guajardo et al., 2017 , 2019 ) highlight the need

Free access

Wilbur Reil, David Ramos, and Ronald Snyder

Two management systems were initiated in a 10 year old Juglans regia cv. Hartley orchard planted 8 m. × 8 m. in 1977. Annual dormant selective pruning was practiced for the next 8 years on all trees within one treatment (pruning) compared to dormant severe pruning on alternate temporary trees with no pruning on adjacent permanent trees (thinning). Temporary trees were removed in the thinning treatment in 1985.

Yield, trunk cross sectional area, pruning weight and nut quality factors were evaluated each year from the 5 replicate, completely randomized trial.

Yield and nut quality factors did not differ between the two treatments during the 15 years.

In 1990 the pruned trial was again pruned causing a 20% drop in production (p=.06). With no additional pruning yield returned to slightly above the thinned treatment in 1991.

This trial demonstrates that Hartley walnut trees (terminal bearing habit) continue to produce satisfactory crops under crowded canopy management but a tree thinning program offers other advantages which also should be considered.

Free access

Robert G. Fjellstrom, Dan E. Parfitt, and Gale H. McGranahan

RFLP markers were used to study genetic diversity among California walnut (Juglans regia L.) cultivars and germplasm collected worldwide. 16 of 21 RFLP markers were polymorphic in the 48 walnut accessions tested. Seven RFLP markers permitted unique identification of all walnut cultivars. All genotypes were heterozygous at approximately 20% of the loci for both California and worldwide germplasm. California walnut germplasm contained 65% of the worldwide allelic diversity. Cluster analysis of genetic distance between accessions and principal component analysis of allelic genotypes showed two major groups of walnut domestication. California germplasm was associated with germplasm from France, Central Europe, and Iran, and had less genotypic similarity with germplasm from Nepal, China, Korea, and Japan.

Free access

Daniel Potter, Fangyou Gao, Giovanna Aiello, Charles Leslie, and Gale McGranahan

The utility of intersimple sequence repeat (ISSR) markers for identification of English or Persian walnut (Juglans regia L.) cultivars was explored. Four cultivars were screened with 47 ISSR primers; eight of these primers, which generated reproducible and informative data, were selected for further study. Two individuals from each of 48 cultivars, including many currently important in the California walnut industry as well as accessions from Europe and Asia, were then examined with the eight ISSR primers. Polymerase chain reaction (PCR) products were separated on agarose gels and stained with ethidium bromide. Fifty-four bands were scored as present or absent in each cultivar; of these, 31 (57%) were polymorphic among the 48 cultivars. Combined data from the eight ISSR primers provided a unique fingerprint for each of the cultivars tested. Fifteen of the cultivars could be distinguished from all others with just one primer, 31 with a minimum of two primers, and two required three primers. Pairwise genetic distances between the cultivars were calculated and a dendrogram was generated using the neighbor-joining algorithm. Some of the groupings in the dendrogram corresponded to groups which, based on known pedigrees, are genealogically closely related. Others included accessions from diverse genetic and/or geographic origins. These results can be attributed to a combination of the limitations of the ISSR method for inferring genetic relationships, on the one hand, and the complex history of walnut cultivar development involving extensive exchange and breeding of germplasm from different geographic regions, on the other.

Free access

R.G. Fjellstrom, D.E. Parfitt, and G.H. McGranahan

RFLP markers were used to investigate genetic diversity among California walnut (Juglans regia) cultivars and germplasm collected worldwide. Sixteen of 21 RFLP markers were polymorphic in the 48 walnut accessions tested. RFLP markers were useful for identifying walnut cultivars. All genotypes were heterozygous at ≈20% of the loci for both California and worldwide germplasm. California walnut germplasm contained 60% of the worldwide allelic diversity. Cluster analysis of genetic distance between accessions and principal component analysis of allelic genotypes showed two major groups of walnut domestication. California germplasm was associated with germplasm from France, central Europe, and Iran and had less genotypic similarity with germplasm from Nepal, China, Korea, and Japan.

Free access

Gilbert F. Simmons, Joseph L. Smilanick, Nuria Denis-Arrue, Dennis A Margosan, and Shama John

A new vapor phase hydrogen peroxide (VPHP) technology that uses relatively dry hydrogen peroxide pulses is a promising method for the disinfection of surface-borne bacteria, yeasts, and molds on walnut nutmeats. The number of colony forming units per gram (cfu/g) on untreated nutmeats was compared to those VPHP treated. Three culture media; dichloran rose bengal chloramphenicol agar base (DRBC, Oxoid), aerobic plate count agar (APC, Oxoid), and potato dextrose agar (PDA, Sigma), were utilized to evaluate cfu/g. Similar numbers of cfu/g of product were observed on APC and PDA. The more selective DRBC had lower cfu/g. Microorganisms washed from untreated walnut nutmeats purchased at retail outlets ranged between 17,000-29,000 cfu/g depending upon the culture medium used. The number of cfu/lg on nutmeats after VPHP treatments was reduced to 500-1400, a 95% reduction. VPHP may offer an alternative to propylene oxide fumigation. The moisture content of nutmeats was not significantly altered by VPHP. The Food and Drug Administration lists hydrogen peroxide as a “generally recognized as safe substance” (GRAS). Hydrogen peroxide is already produced in a food grade for aseptic packaging.

Free access

Kathleen M. Kelley Anderson and Mitchell King

The effect of kaolin (Surround™) on walnut quality parameters, including edible yield, reflected light index, insect damage, off grade, price per pound, and the incidence and severity of sunburn, were evaluated over a 4-year period in `Vina' and `Chandler' walnut orchards. Results indicate that applications of kaolin significantly improved edible yield, reflected light index, price per pound, and the incidence and severity of sunburn in most orchards in most years. Improvements in these parameters were more consistent with the `Vina' cultivar. Off-grade was not significantly reduced by the use of kaolin. Codling moth damage levels were too low to detect in all orchards in all years.

Free access

Kathy Kelley and Dave Ramos

Fifty trees each of 1-year-old Paradox rootstock June-budded to `Chandler' walnut and 2-year-old Paradox whipgrafted to `Chandler' were planted in a 28 × 28-ft spacing on a Hanford sandy loam soil. Ten trees of each type were selected at time of planting and the number of roots, individual root diameter, trunk diameter, root dry weight, scion dry weight, and total dry weight were compared. All parameters, with the exception of root number, were significantly greater for the grafted 2-year-old rootstocks. Growth of the trees measured as trunk circumference 20 cm above the graft union was significantly greater for the grafted 2-year-old rootstocks following the first season. There was no significant different in trunk circumference between the 1- and 2-year-old rootstocks following the second or third growing seasons.