Persian Walnut Cultivars Research Articles

Yield related traits in some Persian walnut cultivars: Analysis of genetic and genetic by environment interaction

The most important trait in tree species, including walnut, is the yield. In this study, the effect of genotype and their interaction with year on Nut weight, Kernel weight, Kernel percentage, Fruit set, Nuts number on Scaffold (Canopy) Cross Area (SCA), Nut weight on SCA and Kernel weight on SCA were evaluated on Caspian, Persia, Alvand, and Chaldoran walnut cultivars. The results showed that the effects of year, genotype, and year × genotype interaction on all traits were significant. The results showed that Alvand had the highest number of nuts (41.8 per m2) and nut weight (472.1 g/m2) on (SCA). Heritability (H2b) for kernel weight and kernel percentage, were estimated 0.75 and 0.80, respectively. The lowest value of H2b (0.36) was belong to fruit set. The analyses of genetic and phenotypic correlations between traits showed that, the nut weight had (rg = 0.31, rp = 0.27) a moderate correlation with SCA same as kernel weight (rg = 0.34, rp = 0.29). The GGE biplot analysis explained most of the existing variations (>90%). The genetic effect (PC1) for all traits were higher respect to the genetic × environment interaction (PC2), especially for the kernel percentage (94.4%) and number and weight of nut and kernel on SCA (>90%). The lowest value of the PC1 was related to the fruit set (65.6%), which indicates the trait was more affected by genetic × environment interactions (21.8%). So, this result showed that the yield-related traits in walnut is highly relevant to environment(year in this study) and evaluation of the new cultivars needs careful attention in this case.

Total lipid and fatty acids components of some Persian walnut (Juglans regia) cultivars

The world's walnuts (Juglans regia L.) production showed rapid growth from less than one million tons to more than three million tons during 1990–2020. The walnut kernel contains a high amount of fats, proteins, and carbohydrates. In this study, the total lipids, proteins, and carbohydrates contents of four commercial walnut cultivars: Alvand, Chaldoran, Caspian, and Persia, together with two promising genotypes: C-25 and 35t, were compared to cv. Chandler in 2019 and 2020. Based on the results, the average percentage of protein in cultivars in two years varied from 15.00% to 19.27%, the percentage of carbohydrates from 17.40% to 29.10%, and the percentage of total lipids from 50.60% to 70.00%. The fatty acids contents showed that the predominant was linoleic acid ranging from 44.60%-63.09%, followed by oleic acid (12.40%-35.02%), linolenic acid (6.64%-14.97%), palmitic acid (7.04%-8.97%) and stearic acid (2.28%-3.63%). Meanwhile, the nut protein (14.90%-19.86%) and carbohydrate (17.40%-29.10%) showed high variability too. The results showed that among the cultivars/genotypes, the highest amount of protein belonged to promising genotype 35t, and the highest amount of total lipid percentage was observed in cv. Persia, and the highest amount of carbohydrates was related to cv. Caspian. The cv. Chandler had the highest linoleic acid content (60.53%), while the cv. Persia had the lowest amount (46.90%). Analysis of regression between fatty acids components showed a close relationship r2 (0.876) between linoleic acid and oleic acid. The analysis of results in two years regarding the total lipids showed that the effect of the year was more than the genotype. Factor analysis using five fatty acids components showed that the first and second factors demonstrated more than 70% of the total variance. The first factor influenced the oleic acid (-0.978) and linoleic acid (0.941) highly. The loading plot of the first and second factors indicated that the change in oleic acid was opposite to linoleic acid, linolenic acid, and stearic acid. In conclusion, walnut cultivars' fatty acids contents showed significant variability, so Chandler, Chaldoran, and 35t were rich in linoleic and linolenic acids. In contrast, others like Persia and C-25 were rich in oleic acid.

Bud break accompanies with the enhanced activities of hemicellulase and pectinase and the mobilization of cell wall thickenings in Persian walnut bud scales

The endo-dormant bud scales of walnut have storage parenchyma cells with thickened walls. During bud dormancy release, cell wall hydrolytic enzymes mobilize pectin and hemicellulose reserves of these cells to fuel bud break. Cell wall hydrolytic enzymes might define specific stages of bud dormancy release. Bud dormancy release is important in woody plants as it is linked to final biomass and yield. This process requires enzyme activities which affect the bud cell wall physico-chemical properties, however, little information is available. Accordingly, the activities of some cell wall hydrolytic enzymes were studied during endo-dormancy release in lateral buds of two Persian walnut (Juglans regia L.) cultivars having low (‘Serr’) and high (‘Hartley’) chilling requirements (CRs). Buds were collected monthly from the leaf shedding stage (November) till bud break and used for enzymatic analysis. In both cultivars, the activities of 1,4-β-D-glucanase, xylanase, mannanase and pectinase increased during dormancy release. In ‘Serr’, first rises in mannanase and pectinase activities occurred before transition to eco-dormancy (January) and the second rises occurred before bud break (March). Similarly, in ‘Hartley’, first rise in mannanase activity observed before transition to eco-dormancy (February) and the second rise before bud break (April). ‘Serr’ buds also displayed significant increase in the activities of hemicellulases and pectinase earlier than ‘Hartley’, however, the latter showed quantitatively higher means for the enzymatic activities. Endo-dormant bud scales had very thick-walled storage parenchyma cells which turned into thinner-walled ones during bud break, suggesting cell wall polysaccharide mobilization by hemicellulases and pectinases. Thus, the activation of cell wall hydrolytic enzymes during endo-dormancy release may contribute to the bud scale cell wall carbohydrate reserve mobilization and/or growth-associated wall relaxation in preparation for bud break. Furthermore, buds from low CR plants may show earlier activation of cell wall-loosening mechanisms during dormancy release.

Four New Persian Walnut Cultivars of Iran: Persia, Caspian, Chaldoran, and Alvand

Four New Persian Walnut Cultivars of Iran: Persia, Caspian, Chaldoran, and Alvand

Frost behavior of Hungarian bred Persian walnut cultivars

Frost behavior of Hungarian bred Persian walnut cultivars

Detection and quantification of some phenolic compounds in kernel of selected Hungarian and Bulgarian Persian walnut cultivars

Detection and quantification of some phenolic compounds in kernel of selected Hungarian and Bulgarian Persian walnut cultivars

Examination of Hungarian bred Persian walnut cultivars’ resistance to frost

Examination of Hungarian bred Persian walnut cultivars’ resistance to frost

Preliminary results of frost hardiness of Hungarian bred Persian walnut cultivars

Preliminary results of frost hardiness of Hungarian bred Persian walnut cultivars

Fatty acid composition, oxidative stability, and antioxidant properties of some Hungarian and other Persian walnut cultivars

Ten different Persian walnut cultivars were examined for their compositional data, including eight Hungarian and two introduced varieties. Oil content and fatty acid composition were determined, as well as oxidative stability (indicated by induction time). Antioxidative capacity, total polyphenol measurements, and individual phenolic compounds were also determined. Not only dry samples but fresh and stored samples were included in this study. Large differences were found among the varieties within these parameters, for example in oxidative stability, which contributes to antioxidative capacity. In conclusion, the nutritional value of Hungarian walnut cultivars was the same or even higher than those of foreign ones.

Phenolic Profile of the Kernel of Selected Persian Walnut (<i>Juglans regia</i> L.) Cultivars

The Persian walnut (Juglans regia L.) also known as English, Carpathian or common walnut is an important fruit species for Central and Eastern Europe, as its productivity increases annually due to its good market situation. Phenolic compounds of fifteen Persian walnut cultivars and two selected genotypes were examined by HPLC in this research paper. If we rank the phenolic compounds of the examined cultivars based on their quantity into increasing relative order, the quantity of Vanillic acid was the highest compound followed by Cathechin, Pyrocathechin, Epicathechin, Rutin, Syringic acid, Gallic acid, Juglone and Cinnamic acid. As results it can be considered that the Hungarian bred walnut cultivars had higher phenolic content compared to foreign cultivars. Among foreign bred cultivars evaluated in this paper the Serbian cultivars ‘Srem’ and ‘Sampion’ had the best results.

Variation in disease development among persian walnut cultivars, selections and crosses when inoculated with Xanthomonas arboricola pv. juglandis in Greece.

A total of 27 walnut (Juglans regia) cultivars (14 lateral and 13 terminal fruit fullness cultivars), 12 selections and 12 crosses were evaluated for their resistance to the walnut blight bacterium Xanthomonas arboricola pv. juglandis. Healthy nuts were inoculated with pure bacterial cultures isolated from diseased nuts. Two weeks after inoculation, the frequency of successful infections, as well as the disease severity was recorded and the index of varietal susceptibility (IVS) was calculated for each treatment. Based on these results walnut cultivars, selections and crosses were ranked in five classes of susceptibility (A to E). The experiment was repeated for two consecutive years, 2007 and 2008. Results showed that all the artificially infected nuts showed typical bacterial blight symptoms as compared to the negative control. Among the cultivars tested Amigo, Asley, Eliana, Franquette and Spurgcan were the less susceptible with average IVS ranging from 13.1 to 24.4, therefore ranked as class A. Walnut selections EK1, EH29 and FM16, as well as crosses PZ-14 and FxH5 also showed low susceptibility. In contrast, the terminal fruit fullness cv. Milotai and the cross S3/1 were highly susceptible and ranked as class E.

Assessment of Physical and Chemical Aspects of New Persian Walnut Cultivars to Optimize Process Conditions

This paper describes comparative analysis some of physical and chemical properties of novel Persian walnut cultivars (cv. Urmia and Toyserkan) grown in Iran. The physical properties in terms of linear dimensions, geometric mean diameter, mass, volume, sphericity, surface area, true and bulk densities, porosity, repose angle, shell ratio and static coefficient of friction of nuts and kernels of the walnut cultivars were determined. The highest fat (66.1%), dietary fiber (4.8%), protein (16.33%), potassium (311mg 100g-1) and magnesium (97.5mg 100g-1) contents were obtained in Urmia cultivar (14.92%). Linoleic acid was the major fatty acid, followed by oleic, linolenic and palmitic acids. Amino acid composition analyses indicated that acidic amino acids were the most prominent group with a range from 31.06% (Toyserkan cultivar) to 31.09% (Urmia cultivar).

Comparative analysis of new Persian walnut cultivars: nut/kernel geometrical, gravimetrical, frictional and mechanical attributes and kernel chemical composition

This study compared some chemical and engineering attributes of three Persian walnut cultivars (Toyserkan, Chaboksar and Karaj) at a moisture content of 3.41% (d.b.). The study experimentally investigated engineering properties of the nut and kernel of walnuts, such as dimensions, the geometric mean diameter, surface area, sphericity, bulk and true densities, porosity, dynamic angle of repose, and static coefficient of friction on four structural surfaces namely, glass, galvanized iron sheet, plywood and steel, as well as nut and kernel rupture force and rupture energy. Chemical analysis showed that carbohydrate content was significantly higher in the Karaj cultivar than in the other two studied, and that the Chaboksar cultivar had the highest fat content. The Toyserkan cultivar had the highest values for protein and minerals (Ca, P, K, Mg, Fe, and Cu). Moreover, most physical properties of nut and kernel were significantly different for each cultivar. The values for sphericity, true density and repose angle for nuts were 83.8–94.0%, 315.5–402.3kgm−3 and 35.3°–38.0°, respectively, while the corresponding values for kernels were 63.7–72.4%, 1018.9–1043.3kgm−3 and 39.8–41.0°, respectively. The ranges of static coefficients of friction on plywood, galvanized iron sheet, glass and steel were 0.385–0.473, 0.307–0.433, 0.284–0.432, and 0.268–0.293 for nuts and 0.348–0.453, 0.332–0.436, 0.306–0.336 and 0.322–0.369 for kernels, respectively. Also, kernel rupture force and energy and the required energy for nut rupturing were significantly different for each cultivar. The Toyserkan cultivar under the Y-axis loading direction had the lowest the force and energy for initial kernel and nut rupture.

Supercooling and Cold-hardiness of Acclimated and Deacclimated Buds and Stems of Persian Walnut Cultivars and Selections

To study the cold-hardiness of Persian walnut cultivars and selections, three methods were compared: 1) thermal analysis; 2) evaluation of tissue health after controlled freezing; and 3) field observations after a severe midwinter freeze. Stem segments and buds were collected from eight Persian walnut genotypes (four commercial cultivars and four promising Iranian selections). Thermal analysis was conducted using thermoelectric modules (TEM) to measure the high (HTE) and low (LTE) temperature exotherms produced when water and tissues freeze. TEM signals were recorded as the temperature of the samples was decreased at a rate of 2 °C/h. Tissue injury under controlled temperatures was evaluated using pre-chilled stem segments cooled at 2 °C/h to set temperatures ranging from –5 to –30 °C and then held at these temperatures for 16 h. Frozen samples were thawed and visually evaluated for severity of injury. Cold damage under field conditions was evaluated after an unusually severe winter freeze. Twigs from affected trees were removed in mid-February and in April and visually rated for extent of injury and ability to recover. The occurrence of LTEs was correlated with death of the tissues as assessed by tissue browning. Both the capacity to supercool and the cold-hardiness of cultivars and selections tested increased with accumulated seasonal chilling and decreased as they approached spring budbreak. Thermal analysis showed a tendency for buds and stems to exhibit multiple LTEs at peak dormancy. The cultivars and selections were classified into three groups based on their cold-hardiness: sensitive (‘Z30’ and ‘Serr’), semihardy (‘Z53’ and ‘Z67’), and hardy (‘Lara’, ‘Hartley’, ‘Z63’, and ‘Pedro’).

IMPROVED ROOTING METHODS FOR WALNUT (JUGLANS) MICROSHOOTS

Modified rooting procedures using etiolated microshoots, extended induction times, and reduced auxin concentrations were examined for rooting a variety of walnut genotypes including Persian walnut (Juglans regia) cultivars and several hybrid selections tolerant to cherry leaf roll virus. These methods generally increased rooting percentages, root number, and root elongation, reduced basal callusing, and reduced the length of time required for root emergence. Etiolation was particularly effective in improving the rooting of the most difficult genotypes but introduced new challenges. Leaves of etiolated microshoots did expand well on the vermiculite-supplemented medium routinely used for root development of green shoots, resulting in poor greenhouse survival of shoots rooted on this medium. Methods were tested to improve leaf expansion concurrently with root development in vitro, to reduce brittleness of microshoot stems, and to reduce damping-off during greenhouse acclimatization. Efforts to improve root quality and to pre-harden shoots before greenhouse acclimatization are continuing.

DESCRIPTIVE ANALYSIS OF KERNELS OF BLACK WALNUT (JUGLANS NIGRA L.) AND PERSIAN WALNUT (J. REGIA L.)

Two types of walnuts are valued for their nuts, the Persian walnut (Juglans regia L.) and eastern black walnut (Juglans nigra L.). While there is a well-established market for Persian walnuts, there is a relatively small, but increasing demand for black walnuts in the United States. In spite of their availability in the marketplace, their similarities in sensory characteristics of kernels, as well as their unique attributes have not been explored. The objective of this study was to characterize selected Persian and black walnut cultivars using aroma, flavor, and texture sensory attributes. Twenty-two terms were used for descriptive analysis of walnut kernels. All but two attributes (fruity and painty/rancid) were common to black and Persian walnut kernels. Black walnuts were distinguished from Persian walnuts by their overall aroma and fruity and musty flavors. Overall aroma, fruity, woody, musty, and sweet flavors also varied among the kernels of some black walnut cultivars. Kernels of Persian walnuts generally had higher ratings of nutty, woody and astringent flavors than those of most black walnut cultivars. This study demonstrated that Persian and black walnut kernels share common sensory attributes, but also have unique characteristics. The aroma and fruity flavor of black walnuts can be promoted in the marketplace, which will distinguish them from Persian walnuts.

PERFORMANCE OF SIX WALNUT CULTIVARS TRAINED AS FREE AND SEMI-STRUCTURED CENTRAL LEADER SYSTEMS

Persian walnut cultivars increase their productivity using less structured training systems. Six lateral bearing commercial cultivars, 'Chandler', 'Ferjean', 'Fernor', 'Howard', 'Lara' and 'Vina' have been evaluated trained under free (FL) and semi-structured (SSL) central leader systems. The orchard trial has been controlled from planting, 1999, to 2008 harvest. Data of growth and production were recorded on ten trees per cultivars and the training system distributed across five blocks. At the sixth leaf, training was finished (2004). At the end of this juvenile period, at 7 th leaf, the cultivar growth ranking was as expected. 'Chandler', 'Fernor' and 'Vina' showed medium vigour and 'Ferjean', 'Howard' and 'Lara' low vigour. At this age, all the trees were at least 7 m high for any cultivar and training. During the training period the wood pruned weight was up to 50% higher in SSL. Cultivars with upright or spreading growth habits needed more pruning. 'Howard' was the most easily trained, while 'Vina' and `Fernor' were the hardest. The production still favours FL at 8 years. Nuts showed a good size, at least 11 g, in all cultivars and training evaluated. However, it is clearly difficult to maintain enough light in the canopy in the adult phase in some cultivars like 'Lara' or 'Vina'. Orchards of those cultivars need more pruning to maintain marketable nut size.

EVALUATION OF CHILLING-HEAT REQUIREMENTS OF SOME PERSIAN WALNUT CULTIVARS

The objective of this work was to determine the chilling and heat requirements of Persian walnut cultivars and genotypes using excised twigs. The experiment was carried out from November to March 2006 and 2007. One-year-old twigs were prepared from four cultivars and four domestic genotypes (Juglans regia L.). After leaf fall, the twigs were taken and placed in plastic bags and kept at 4±1°C to provide 400 to 1500 chilling hours. After chilling, the excised twigs were transferred to the greenhouse. The cultivar 'Serr' and 'Z 30 ' genotype had the lowest chilling requirements (650 hours). 'Lara', `Z 63 ', 'Z 53 ', 'Pedro' and 'Z 67 ' showed intermediate chilling requirements, with values of 900, 900, 800, 750 and 750 hours, respectively. Finally, 'Hartley' completed its dormancy after the accumulation of 1000 hours, being the walnut cultivar with the highest chilling requirement in our study. The cultivars and genotypes were classified into three groups based on their heat requirements: low requirement ('Z 30 ' and 'Serr'), medium requirement ('Z 53 ', 'Z 67 ', 'Lara' and 'Pedro') and high requirement ('Hartley' and `Z 63 ').

Estimation of Chilling and Heat Requirements of Some Persian Walnut Cultivars and Genotypes

The objective of this work was to determine the chilling and heat requirements of Persian walnut cultivars and genotypes using excised twigs. The experiment was carried out from Nov. 2006 and 2007 to Mar. 2007 and 2008. One-year-old twigs were prepared from four cultivars and four domestic genotypes of Juglans regia L. After leaf fall, the twigs were taken and placed in plastic bags and kept at 4 ± 1 °C to stimulate 400 to 1500 chilling hours. After chilling, the excised twigs were transferred to the greenhouse with a natural photoperiod and a temperature from 18 to 27 °C. The evaluation of budbreak was made three times a week and the number of accumulated growing degree hours (°C) was determined until the buds reached the balloon or green tip stage. The chilling requirements were lowest (400 h) for catkins and highest (1000 h) for lateral buds. The Serr cultivar and ‘Z30’ genotype had the lowest chilling requirements (650 and 650 h). ‘Lara’, ‘Z63’, ‘Z53’, ‘Pedro’, and ‘Z67’ showed intermediate chilling requirements with values of 900, 900, 800, 750, and 750 h, respectively. Finally, ‘Hartley’ completed its dormancy after an accumulation of 1000 h, being the walnut cultivar with the highest chilling requirement in our study. As the final result, the cultivars and genotypes were classified into three groups based on their heat requirements: low requirement (‘Z30’ and ‘Serr’), medium requirement (‘Z53’, ‘Z67’, ‘Lara’, and ‘Pedro’), and high requirement (‘Hartley’ and ‘Z63’).

Descriptive analysis of kernels of selected black and Persian walnut cultivars

AbstractBACKGROUND: Two types of walnut are valued for their nuts, the Persian walnut (Juglans regia L.) and eastern black walnut (Juglans nigra L.). While there is a well‐established market for Persian walnuts, there is a relatively small, but increasing demand for black walnuts. In spite of their availability in the marketplace, their similarities in sensory characteristics of kernels, as well as their unique attributes have not been explored. The objective of this study was to characterize selected Persian and black walnut cultivars using aroma, flavor, and texture sensory attributes.RESULTS: Twenty‐two terms were used for descriptive analysis of walnut kernels. All but two attributes (fruity and painty/rancid) were common to black and Persian walnut kernels. Black walnuts were distinguished from Persian walnuts by their overall aroma and fruity and musty flavors. Overall aroma, fruity, woody, musty and sweet flavors also varied among the kernels of some black walnut cultivars. Kernels of Persian walnuts generally had higher ratings of nutty, woody and astringent flavors than those of most black walnut cultivars.CONCLUSION: This study demonstrated that Persian and black walnut kernels share common sensory attributes, but also have unique characteristics. The aroma and fruity flavor of black walnuts can be promoted in the marketplace, which will distinguish them from Persian walnuts. Copyright © 2008 Society of Chemical Industry