Percentage Of Kernels Research Articles

Development of a core collection in Iranian walnut (Juglans regia L.) germplasm using the phenotypic diversity

Persian walnut (Juglans regia L.) is a very important nut crop with increasingly attention in the world. It was among the fruit tree species that has been propagated sexually, up to some decades ago. So, there were no or limited cultivars and the breeding works are usually new. In order to release new cultivars, a walnut improvement program started in Iran in 1980s. There was established a walnut collection, with selection of some superior genotypes from the orchards together with some introductions. As, the comprehensive characterization of germplasm is necessary in the breeding programs, in this study a collection of 104 Persian walnut accessions has been evaluated especially in order to create a core or breeding collection with reduced number of accessions and keeping maximum variability. To carry out this work, 18 walnut important traits were evaluated during 2014 and 2015 in the walnut collection of Horticultural Science Research Institute, Karaj, Iran. A wide variation was observed for several important characteristics such as leafing date (from March, 5 to April, 27), nut weight (6.60–15.33 g), kernel weight (2.67–8.21 g), and kernel percentage (35.39–71.09%). Significant correlations were observed between traits. Factor analysis showed that the six major factors affecting traits were explaining 79.9% of the total variance. The analysis, using maximization strategy through a heuristic algorithm, determined a core collection consisted of 27 accessions with similar variability respect to primary collection (mean difference percentage = 9.88% and coincidence rate of range = 95.05%). The parameters showed that this core includes 100% coverage of the primary diversity. According to result the F-test revealed no-significant differences for all traits. In this paper, for the first time, a walnut core collection was established from a primary collection. Conservation of this core collection could be more economic and better manageable for breeding purposes.

Infection incidence, kernel colonisation, and mycotoxin accumulation in durum wheat inoculated with Fusarium sporotrichioides, F. langsethiae or F. poae at different growth stages

A 2-year field experiment was conducted to determine the effects of Fusarium sporotrichioides, F. langsethiae, or F. poae on durum wheat plants artificially inoculated at different growth stages. The percentage of symptomatic kernels was similar among the three species, but incidence of infected kernels was lower for F. langsethiae. Kernel colonization was higher when plants were inoculated before and during anthesis for F. sporotrichioides and F. poae, but unaffected by timing of inoculation for F. langsethiae. Production of T-2/HT-2 toxins was higher for F. sporotrichioides than for F. langsethiae. Significant accumulations of nivalenol were detected for F. poae. Across all three species, there was a weak correlation (r = 0.16; P = 0.031) between the incidences of symptomatic and infected kernels, but a stronger correlation (r = 0.53; P 0.58; P < 0.007) with infection incidence or fungal DNA in kernels, but only for F. sporotrichioides and F. poae.

The pomological characterization of walnut (Juglans regia L.) to select the superior genotypes – An opportunity for genetic improvement

Persian walnut (Juglans regia L.), the cultivated walnut species for nut production, is one of the main oldest food sources. In the present investigation, a total of 908 walnut seedling originated genotypes were studied to detect the phenotypic variation and to select the superior genotypes based on the fruit traits. Considerable phenotypic variation was found among the genotypes based on the measured traits. The nut diameter ranged from 20.00 to 43.35 mm, while nut length ranged from 22.20 to 47.42 mm. Nut weight ranged from 5.42 to 23.00 g and also it was between 12.00 and 18.00 g in 551 genotypes, while nut weight was very large in 37 genotypes and ranged from 18.14 to 23.00 g. Kernel weight varied from 2.30 to 14.00 g and 568 genotypes had the kernels with the ranges between 6.00 and 10.00 g, while kernel weight in 19 genotypes was very large and ranged from 10.01 to 14.00 g. Kernel percentage ranged from 24.66 to 75.10% that 507 genotypes had more than 50.00% kernel percentage. Based on the ideal values for the main traits in walnut including nut weight, kernel weight, and kernel percentage, 329 genotypes had ideal values for these traits. Thus, they can be cultivated in orchards and/or to be useful as parents for crossing to create proper populations or improve cultivars.

Genetic variability, heritability and genetic advance of yield and related traits in F3 generation of groundnut (Arachis hypogaea L.)

Groundnut is a highly self-pollinated crop and due to the uniformity of the traits imposed by the peanut growers, it is losing its genetic base. Hence, there arises a concern for creating more genetic variability in the population. With this information in background, the present study was carried out to examine the variability of prominent yield and yield attributing traits in this unpredictable legume crop. This will provide insight into the expression of traits and the influence of environment on those traits. High GCV, PCV values were recorded for the number of pods per plant, 100 pod weight, 100 kernel weight, shelling percent and number of mature kernels in the present study. This indicates the presence of ample variability for these traits. Hence these traits can be opted for selection as they contribute more towards variability with least influence of environment over it. Most of the traits recorded high heritability and high GAM, which is a positive sign for least influence of environment on population and presence of additive gene action.

Fissure Detection and Measurement in Rough Rice Using X-Ray Imaging

Abstract. Fissures in rice kernels that develop prior to harvest and post-harvest processing significantly reduce head rice yield, a crucial parameter for evaluating rice quality and economic value in the rice industry. In this study, fissures in rough rice were revealed by scanning approximately 50 rough rice kernels at a time using an x-ray system. An algorithm was developed to detect and measure fissures in rough rice kernels in the x-ray images using the Python programming language coupled with the OpenCV library. This algorithm successfully segmented individual rice kernels in the x-ray images using the gap-filling method. The algorithm detected fissures by adaptive thresholding of each rice kernel and applying a series of filters. Data on kernel parameters (number, area, length, and width) and fissure parameters (percentage of kernels fissured and fissure number, area, and length per kernel) were produced for the images to characterize kernel size and fissuring levels of the rice sample. This algorithm demonstrated good repeatability in measuring kernel and fissure parameters, with relative standard deviations of less than 4% and 9%, respectively. The accuracy of the developed algorithm in measuring fissures was validated by visual inspection of rough rice, with a deviation of less than 2% in percentage of kernels fissured. The fissure detection and measurement algorithm provides a useful tool for quantifying fissures in rough rice samples using x-ray imaging. This information could be used to quantify fissuring levels and predict head rice yield for rough rice samples without a cumbersome milling process. Keywords: Cracks, Fissure, Imaging, Rice, X-ray.

Zinc Nutritional Status on Physiological and Nutritional Indicators, Metabolism of Oxidative Stress, Yield and Fruit Quality of Pecan Tree

In the United States of America and in Mexico, zinc deficiency is a common nutritional disorder in pecan trees [Carya illinoinensis (Wangenh.) C. Koch], especially in calcareous soils. This study in Chihuahua, northern Mexico, analyses the effects of zinc nutritional status on various physiological and nutritional indicators, on the metabolism of oxidative stress, and on the yield and fruit quality of pecan. The aim was to identify possible bioindicators of soil zinc deficiency. The experimental design was completely randomized with four nutritional conditions with respect to zinc: a control and three levels of zinc deficiency - slight, moderate and severe. Zinc deficiency is characterised by small leaves with interveinal necrosis and rippled leaf margins. The lowest values of leaf area, SPAD values, total N and NO3 concentration were observed under conditions of severe zinc deficiency. With worsening zinc deficiency, results indicate an increased enzymatic activity of superoxide dismutase, catalase and glutathione peroxidase. Interestingly, under severe zinc deficiency there are decreases in trunk cross-sectional area growth, in yield and in percentage kernel. Increased activity of superoxide dismutase, catalase and peroxidase enzymes is associated with detoxification of reactive oxygen species. The activity of enzymes detoxifying reactive oxygen species lessens the negative effects of zinc deficiency stress, and may be good bioindicators of zinc deficiency and its visual symptoms on pecan trees.

The role of ear environment in postharvest susceptibility of maize to toxigenic Aspergillus flavus

AbstractA kernel screening assay (KSA) was used to assess the genetic and environmental effects on the vulnerability of maize to aflatoxin accumulation. Kernels of 26 inbred lines that had been grown in seven environments, and 190 lines of the Intermated B73xMo17 (IBM) population grown in one location in the United States, were inoculated with a toxigenic strain of A. flavus and incubated in the dark at 30°C for 6 days. Percent kernel colonization (PKC), sporulation and aflatoxin were influenced by the maize genotypes (G), the location (“ear environment” or E) and the GxE interactions. Overall, low broad‐sense heritabilities were observed for PKC, sporulation and aflatoxin. PKC was significantly correlated with sporulation in all environments. Aflatoxin was positively correlated with colonization for two and with sporulation for all ear environments. Higher grain sulphur or magnesium in IBM was associated with less colonization or aflatoxin. Postharvest susceptibility of maize to aflatoxin is thus influenced by factors that are modulated by the ear environment. In a KSA, sporulation could be a proxy test for aflatoxin accumulation.

Morphological and Pomological Variability Analysis of Walnut (Juglans regia L.) Genetic Resources from the Middle and High Atlas of Morocco

The walnut (Juglans regia L.) is a traditional fruit crop in Morocco. This species is cultivated in mountain in different environments. However, little data is available on its genetic diversity and its adaptability. Morphological characters of leaf and fruit from 11 Moroccan accessions of walnut were used to assess phenotypic variation of this species. Significant differences were found between accessions for the most examined traits, indicating a high phenotypic diversity. Multivariate analyses lead to identify three groups of accessions. The first group composed by the accessions of both Middle and High Atlas Mountain with high weigh and percentage of kernel and low thickness of shell. The second group included the accessions for the High Atlas Mountain characterised by large leaf, high nut dimension and great nut size. The third group is composed by two accessions, one belongs to the Middle Atlas Mountain and the other originating from High Atlas Mountain, which are characterized by small leaf and nut. Then, the structuration of accessions in three groups was not correlated to the mountain range type. Moreover, this study showed a significant phenotypic heterogeneity between the eleven studied accessions which opens the way for the strategies for their conservation and the selection of efficient genotypes with the desired traits.

Moisture content, insect pest infestation and mycotoxin levels of maize in markets in the northern region of Ghana

Reliable quantitative data on maize post-harvest losses and factors that cause them in northern Ghana are limited. In this study we assessed maize at six markets in the Northern Region of Ghana, in and around Tamale, during the harvest and storage period of October 2015–June 2016. Across all the markets and sampling periods grain temperature was 32.6 ± 0.2 °C and equilibrium moisture content (EMC) was 9.5 ± 0.2%. EMC tended to decrease to a low in January and February and then increased again, while mean maize temperature was above 30 °C in all months. The primary stored product insects collected from the samples were Tribolium castaneum (Herbst), Sitophilus spp., Rhyzopertha dominica (Fauvel), and Cryptolestes ferrugineus (Stephens). Using all the market and sampling month data, there was a significant correlation between EMC and total number of insects recovered, but not between total number of insects and temperature. The average percentage of insect-damaged kernels (IDK) in the maize sampled across all the markets and sampling periods was 2.7 ± 0.2%, with a range between 0 and 21.4%. Using all the market and sampling month data, levels of insect damage tended to be positively correlated with maize moisture, but not temperature, and levels of insect damage increased with number of stored product insects recovered. The action threshold for aflatoxin in maize in Ghana is 15 ppb, but overall mean aflatoxin level was 19.8 ± 1.5 ppb and aflatoxin levels ranged from 0.3 to 132.2 ppb, with 53% of the samples having levels above 15 ppb. The mean fumonisin level was 1.2 ± 0.0 ppm, which is below the 4.0 ppm action threshold for Ghana. Our results show that aflatoxin levels were high in the market maize in Northern Region of Ghana and insects were prevalent, even though grain moisture tended to be relatively low, especially compared to the Middle Belt of Ghana.

Evaluation of the suitability and optimal use of postharvest storage bag technologies and a combination thereof for maize storage in Nigeria.

The severity of postharvest losses varies considerably depending on storage method and prevalence of storage insect pests known to bore into storage bags. Polypropylene (PP) bags used by smallholder farmers in Nigeria do not provide effective protection for stored produce due to insect boring activities. Deltamethrin incorporated polypropylene, ZeroFly® (ZF) and ZeroFly® Hermetic Storage Bags are technologies with potential to improve protection of stored food commodities against insect attack. Therefore, a 12-month study was conducted in Ibadan, Nigeria to determine the suitability and potential of combined postharvest bag technologies involving ZeroFly® (hermetic and non-hermetic) bags for smallholder farmers when exposed to Sitophilus zeamais and Prostephanus truncatus infestation pressure. Cleaned but un-fumigated 50-kg lots of maize were used to fill bags in each of the following 8 treatments — PP and ZF bags alone, diatomaceous earth-treated maize in PP and ZF bags, single and double hermetic liners in ZF bags, single hermetic liner in PP bags and lastly PICS bags. Results obtained over a 12-month period showed infestation by S. zeamais, Tribolium castaneum, Cryptolestes ferrugineus and Liposcelis spp. and abundance of insect increased with storage period in PP and ZF bags without liner. The percentages of insect damaged kernels by number (IDK) were higher in PP and ZF bags without liner and were 5.4 and 16.9%, respectively; in ZeroFly bags with hermetic liners, these values were ~ 0.5%. The PP and ZF bags without liner also had higher weight loss values of 1.4 and 6.7%, respectively compared with ZeroFly bags with hermetic liners and PICS bags which had a relatively lower weight loss of =0.2%. These results indicate that the ZeroFly Hermetic bag mitigates insect infestations, thereby offering a suitable alternative towards achieving significant reduction in postharvest losses during storage.

Effect of colemanite boron fertilization on hazelnut (Corylus avellanaL.) yield and nutrient concentration of leaf

In this research, the effect of boron fertilization on leaf mineral concentration, nut yield and percent kernel in 'Tombul' hazelnut was determined. The experiment in a randomized complete block design was carried out in a farm orchard with soil B concentration of 0.02 mg kg(-1) in Carsamba-Samsun location in 2013 and 2014 using boron fertilizer of colemanite source. Boron fertilization was carried out as 6 g B ocak(-1) (T(1)) and 12 g B ocak(-1) (T2), along with the control (T(0)). Supplying doses of colemanite (T(1) and T(2)) resulted in an increase in nut yield in both years, in comparison to the control. The yield increase due to boron application in the first year was statistically nonsignificant. In the second year, boron fertilization caused a significant yield increase from 55.5 kg da(-1) in the control plot to 69.2 and 72.4 kg da(-1) in T(1) and T(2) applications, with a 24.7 and 30.4% yield increase, respectively. As a result of increasing doses (T(1) and T(2)) of B fertilization of colemanite source, increases in nut yield were determined. 6 g B ocak(-1) soil colemanite application produced significant yield increases in both years as compared to the control and percent kernel, these increased from 48 to 52%, and from 46 to 50% in the first and second year with 8.3 and 8.6% increases, respectively. In hazelnut orchards with boron deficiency, boron fertilization increased the cluster formation, nut yield and percent kernel, decreasing empty hazelnuts.

Nut characteristics of ‘Fosa’ and ‘Kargalak’ hazelnuts related to number of nuts per cluster

This research was conducted to determine nut dimensions change as a function of number of nuts cluster(-1) (one, two, or three) in 'Fosa' and 'Kargalak' hazelnuts grown in Sakarya and Trabzon districts in Turkey in 2016. Randomized block designs with three replications were used. Nine ocaks were used for each cultivar, for a total of 18 ocaks in total. The nut traits investigated were nut weight, nut length, nut width, nut depth, shell thickness, kernel percentage, kernel weight, kernel length, kernel width, kernel depth, and diameter of the central cavity. The results showed that nut weight, kernel weight, kernel percentage and shell thickness in both 'Fosa' and 'Kargalak' decreased as the number of nuts cluster(-1) increased. Further, nut and kernel dimensions in both cultivars decreased as the number of nuts cluster(-1) increased.

Effect of irrigation regimes by mini sprinkler on yield and pomological traits in ‘Tombul’ hazelnut

This research was conducted to determine the effect of different irrigation regimes by mini sprinkler method on yield and quality parameters of 'Tombul' hazelnut in Giresun (Turkey) in 2015. The experiment was a completely randomized design with one factor and three replications. Hazelnut ocaks (multiple stem system) were pruned in 2014, 5 stems were kept in each ocak. The ocaks were irrigated with mini-sprinklers at three different water levels (0, 50, and 100%). The results showed that the yield was affected by irrigation levels. The highest yield (3.36 kg ocak-1) was obtained at irrigation level of 65% of full irrigation water amount determined by using curve fitting approach. The control (0%) gave the lowest yield (1.41 kg ocak-1). Irrigation levels had a significant effect on nut weight, shell thickness, kernel weight, kernel size, blank nuts, kernel defects, good kernels and L* color value in kernel powder. However, nuts per cluster, nut size, internal cavity size, kernel percentage, small nuts, average blanching rate, a* and b* color values in kernel powder were not affected significantly. The highest values of nut weight, shell thickness, kernel weight, kernel size, nut blanks and kernel defects were obtained from control (0%) treatment, and the highest percentage of good kernels was obtained from the irrigation level of 50%.

Clonal selection in ‘Tombul’ hazelnut: preliminary results

There are 18 registered hazelnut cultivars grown in Turkey. Among these, 'Tombul' has the highest quality. Some morphological variations have been observed among 'Tombul' plants, ocaks and orchards. A research project was carried out between 2007 and 2012 to identify superior 'Tombul' clones in Giresun and Trabzon provinces where this cultivar is widespread and the ecological conditions are ideal for hazelnut. A total of 380 'Tombul' plants were evaluated for three years, and 29 of them were selected based on yield and quality. Before proceeding with replicated trials the identity of these selections was verified. Molecular analysis using AFLP and SSR markers showed that 14 selections were found to be genetically different (clones) from the standard 'Tombul'. These clones were propagated in 2013 and a replicated trial was established in 2014. Phenological observations and pomological analyses were made in 2015 and 2016. The cumulative yield was 82.2 g plant(-1) in standard 'Tombul' while higher cumulative yields were recorded in selections of 61C17 (181.2 g), 28G13 (134.8 g), 28P01 (118.3 g), 28M15 (108.1 g), 61V25 (107.3 g) and 28K16 (86.7g). Differences were also noted in nut and kernel sizes (15.4-16.8 and 11.8-14.1 mm, respectively) and weights (1.65-1.95 and 0.89-1.07 g, respectively), shell thickness (0.91-1.02 mm), percent kernel (50.8-55.7%), internal cavity diameter (1.62-2.35 mm), ratio of good kernels (82.5-100%), and in plant characteristics such as plant height (165-211 cm), stem diameter (31.7-38.6 mm) and number of suckers (17.9 to 29.2). Evaluation of the selections will continue for several more years.

Nut and kernel characteristics of hazelnut cultivars in an area outside the commercial production region in Turkey

Ankara province is located in Central Anatolia where a continental ecology dominates. Winters are cold, summers are hot and dry, humidity is low, and soil has high pH. In this study, performance of 46 hazelnut cultivars and selections were investigated in Ankara in 2015 and 2016. The continental ecology of Ankara had strong negative effects on nut and kernel traits. The average nut and kernel weights were 29.4 and 31.4% lower, respectively, for Turkish cultivars compared to the Black Sea region. Similarly, nut weights of ‘Barcelona’, ‘Ennis’, ‘Hall’s Giant’, ‘Gem’, ‘Willamette’, ‘TGDL’, ‘Tonda di Giffoni’, ‘Mortarella’, ‘Casina’ and ‘Segorbe’ were 37.0% lower on average. However, percent kernel was 6.2% higher in the Turkish cultivars, possibly due to better fill of the small nuts by the kernels. In Turkish cultivars grown near the Black Sea, the pellicle is easily removed from the kernels by dry heat (85-94% blanching), but in Ankara the range was 0.0-47%. ‘Tombul’ and ‘Fosa’ had a very low yield (<0.05 kg plant(-1)), but interestingly ‘Willamette’ had the highest yield (3.12 kg plant(-1)) followed by ‘Pauetet’ (1.92 kg), OSU 720.093 (1.74 kg) and ‘Tonda di Giffoni’ (1.55 kg). These genotypes have short and open husks and could be grown in Ankara since their kernels may have value for processed hazelnut products or oil production but not for the blanched kernel market. The Spanish ‘Negret’ was the most sensitive to this harsh ecology, as the trees did not survive although they were planted several times.

Construction of a high-density genetic linkage map and QTL analysis for hazelnut breeding

Hazelnut breeding is a slow activity due to the long lifecycle of the plant, the long time between pollination and reliable phenotype observation in the progeny, the presence of self-incompatibility and the high level of heterozygosity. Improved knowledge on the hazelnut genome and the development of marker-assisted selection would greatly facilitate breeding programs. Objective of this study was the construction of high-density genetic maps and the detection of QTL (quantitative trait loci) related to phenological, vegetative and productive traits, by using an F1 progeny obtained by crossing ‘Tonda Gentile delle Langhe’ (female parent, hereafter TGdL) with ‘Merveille de Bollwiller’ (syn. ‘Hall’s Giant’ male parent, MB). Genotyping-by-sequencing (GBS), followed by SNP mining using a Samtools-based pipeline, yielded 7,980 SNP markers. Independent linkage maps were constructed for each parent on the basis of the double pseudo-testcross mapping strategy. The linkage map for TGdL consisted of 1,236 markers covering a total genetic length of 900.4 cM, with a mean inter-marker distance of 0.83 cM. A reciprocal translocation was detected in TGdL between two non-homologous chromosomes. The linkage map for MB was based on segregation at 1,211 markers covering a total genetic length of 899.1 cM, with a mean inter-marker distance of 0.82 cM. Plant and nut traits were recorded during five years and statistically analyzed with molecular data to identify marker/QTL associations for flowering and bud burst time, sucker habit and nut traits, such as nut and seed size, roundness index, percent kernel and ease of pellicle removal.

Effect on fruit quality traits of hazelnut cultivars when picking by hand from branch and ground

Research on fruit quality traits was carried out on the hazelnut ‘Cakildak’, ‘Fosa’, and ‘Tombul’ grown in Kocaali county of Sakarya province, Turkey, in 2009 and 2010. For this research, three orchards were defined and studied with three replicates for all cultivars. Each replicate was represented by three ocaks. The nut samples were harvested from a total of 27 ocaks either by picking directly from the branch or the ground, following a randomized block design based on cultivar or harvest treatment. For each replicate, nut weight and size, shell thickness, kernel weight and size, internal cavity size, kernel percent, the proportion of poorly filled nuts, shriveled kernels, blank nut ratio, good kernel ratio, pellicle removal ratio, and small nut ratio were determined. Further, pellicle removal and small nut proportions were also determined. As a result of this study, it can be said that quality traits were significant to picking method × cultivar interaction and better results were obtained picking by hand from ground. In general, the samples that were picked from the branch had thicker shells, more internal cavity space, a larger ratio of poorly filled nuts, and more shriveled kernels then nuts picked from the ground. In the case of the samples which were picked from ground, they had a greater nut weight, nut size, and better ratio of good kernel compared to those picked from branch. In addition, the heaviest nuts and kernels and the largest nuts and the lowest small nuts were determined in ‘Fosa’, ‘Cakildak’, ‘Tombul’, respectively.

Postharvest differences between ‘Tombul’ and ‘Palaz’

The aim of this study was to determine the physical traits of hazelnuts dried by different drying methods during 18 months of storage at 20-25°C and 70-90% RH. The results showed that there was no significant difference among drying methods. However, ‘Tombul’ was more sensitive than ‘Palaz’ in respect to the presence of rotten kernels, moldy kernels and yellowing. The average changes in measured properties during the storage were 1.82-2.06 for nut weight and 0.89-1.08 g for kernel weight, 2.44-2.86 mm for kernel cavity, 54.5-59.9 for kernel percentage, 96.7-100 for fully developed nuts, 8.7-16.7 for shriveled, 6.7-10.0 for black tips, 0.0-3.3 for rotten, 0.0-2.2 for concealed rots, 0.0-12.2 for moldy, 0.0-4.4 for invisible mold, 1.40-24.4 for yellowing, 0.0-7.8 for sour taste, and 10.0-20.0% for kernel defects. Consequently, inshell hazelnuts can be stored at ambient temperature for one year without significant changes in physical properties.

New hazelnut cultivars from Oregon State University

The hazelnut breeding program at Oregon State University (OSU) is developing new cultivars with high nut yield, few defects, and good kernel quality. Every year, approximately 4500 seedlings are planted and evaluated for seven years. The very best of these seedlings are put through a second period of testing in replicated yield trials to determine their potential as cultivars. The fungal disease eastern filbert blight (EFB) is now widespread in the Willamette Valley, so current trials include only EFB-resistant selections. In this paper, we summarize data for three recent releases. ‘York’ (OSU 878.048) is a widely compatible mid-season pollinizer with nuts and kernels that blend well with other recent OSU releases. ‘Wepster’ (OSU 894.030) and ‘McDonald’ (OSU 880.027) were released as main crop cultivars. Trees of ‘Wepster’, ‘McDonald’, and ‘York’ have rounded, moderately upright growth habits, and mature nuts 7-14 days before ‘Barcelona’. ‘Wepster’ nuts and kernels are small, similar in size to ‘Yamhill’, and have very few defects. The percent kernel of ‘Wepster’ is only 44% on average, but total nut yields are very high. ‘McDonald’ nuts are medium to small in size and are suitable for the kernel market. Nuts and kernels of ‘York’ are of good quality, but trees yield less than what is desirable for a main cultivar. ‘York’ has incompatibility alleles S(2) and S(21), but only the uncommon S(21) is expressed in the pollen. It is an excellent mid-season pollinizer, producing large quantities of highly viable pollen over a period of several weeks, and is compatible on most other genotypes. ‘Wepster’, ‘McDonald’ and ‘York’ are fully cross-compatible and are recommended to be planted together. All three are protected with US Plant Patents.

Shell hardness in almond: Cracking load and kernel percentage

Shell-cracking load was measured in a sample of 54 almond cultivars, most of them from the autochthonous germplasm of Majorca (Spain), through a compression test. The shell-cracking load ranged from 58 N in ‘Nonpareil’ to 1415 N in ‘Alzina’, showing the large variability of shell hardness in almond nuts, distributed in 21 mean groups. The results confirmed the suitability of this method for estimating shell hardness due to its reproducibility and small variance within cultivars. Although shell hardness has been traditionally correlated with shelling percentage, our results show that shell hardness may be an independent variable due to its weak correlation with shelling percentage, nut weight and kernel weight. Additionally, our results show that the hardness scores in almond need to be revised.