Nut Characteristics Research Articles

Mechanisms of Cache Decision Making in Fox Squirrels (Sciurus Niger)

The cache decisions of scatter-hoarding animals are influenced by a number of factors, including satiety, food quality, number of competitors, and the risk of predation and pilferage. However, it is unknown how animals assess these variables. We investigated this process experimentally in free-ranging fox squirrels (Sciurus niger) by measuring the effects of nut characteristics and social context on nut-handling behavior and subsequent cache decisions. We found that a behavior involved in nut handling, the head flick, was correlated with nut quality, shell presence, the decision to cache rather than eat the nut, and the time and energy spent caching. In contrast, a 2nd nut-handling behavior, the paw maneuver, was correlated with the social context but not the cache decision, and may instead reflect a response to social competition. Our results suggest that fox squirrels assess nut quality using overt, observable nut-handling behaviors. The experimental study of these behaviors can help us understand how animals use information about food and the social context to make adaptive food-storing decisions.

Morphological diversity of Pistacia species in Iran

Pistachio is one of the most important horticultural crops in Iran. Selection of suitable genotypes, resistant to unfavorable environmental and soil conditions and diseases, are important for increasing yield efficiency and the acreage of this important crop. The aim of this research was to evaluate wild pistachio species and genotypes native to Iran and also to determine any relationships that exist according to their phenotypical characteristics. A total of 11 pistachio types in situ from Kerman and Fars provinces and ex situ from the Iranian Pistachio Research Institute (IPRI) were used during the research. Thirty-one morphological characteristics (17 quantitative and 14 qualitative) were evaluated based on the pistachio descriptor (IPGRI). Results from simple correlation analyses showed significant positive and negative correlations in certain important characteristics. Nut thickness and weight were in significant correlation with the size (dimensions) of the leaves and terminal leaflets. Factor analysis was used to determine the effective characteristics and the number of main factors. For each factor loading a value of more than 0.65 was judged as being significant. Effective characteristics were categorized into seven main factors that contributed to 94% of the overall variance. Leaf and nut characteristics were defined mainly by the first factor contributing to 40% of the total variance. Pistachio genotypes were clustered based on seven factors and at a similarity distance of 10, these were further divided into three sub-clusters each consisting of genotypes belonging to species P. vera L., P. khinjuk Stocks. and P. atlantica Desf. Based on the results, P.khinjuk was located between the other two species, but resembled P. atlantica more than P. vera.

Morphological variation among Persian walnut (Juglans regia) genotypes from central Iran

Fifty‐eight mature Persian walnut (Juglans regia) seedlings growing at six sites in the mountainous regions of Taft, in central Iran, were evaluated to determine their morphological variation and to identify promising individuals. The traits investigated included phenological characteristics, such as budbreak and nut maturity time, and nut characteristics, such as nut and kernel weight, kernel ratio, and shell thickness. Yield efficiency and fruit‐bearing habit were also investigated. The average fruit characteristics: nut weight, kernel weight, kernel ratio, and shell thickness were in the range of 6.0–15.2 g, 2.6–9.1 g, 38.4–79.6%, and 0.4–1.4 mm, respectively. The promising genotypes were AA33, AA35, AA115, AA116, and BA150. These trees had larger nuts (AA116), heavier nuts (15.2 g, AA33), heavier kernels (9.1 g, AA33 and AA115), higher kernel ratio (79.6%, AA35), and later budbreak (BA150). A few significant correlations were found between nut weight and nut length (0.57), nut width (0.68), nut thickness (0.67), kernel weight (0.75), and shell thickness (0.32); whereas a negative correlation was detected between shell thickness and kernel ratio (‐0.34). The data correlation matrix was subjected to principal component analysis, a technique that reduced the dimensionality of the data set and revealed the dominating variables. Cluster analysis of the selected genotypes detected three cluster groups. However, no significant relationship was found between morphological diversity and site geography. The promising selected genotypes identified in central Iran will be further exploited by walnut breeding programmes for their tree and nut characteristics.

Effects of planting density on yield and quality characteristics of hazelnut (cv. Palaz) in a hedgerow training system

Effects of plant density on yield and nut characteristics of Palaz hazelnut (Corylus maxima Mill.) grown in a hedgerow training system in the Black Sea region of Turkey were investigated between 1998 an d 2001. Five planting densities, from 2000 to 6000 plants ha-1, were evaluated. Yield per hectare varied among years, but increased logarithmically with planting density each year. Nut and kernel characteristics varied among years by were not affected by planting density. Key words: Hazelnut, planting density, hedgerow, ocak, training system

Potential of ethephon, NAA, NAD and urea for thinning pistachio fruitlets

Abstract Alternate bearing, the occurrence of high yield ‘on’ year followed by low yield ‘off’ year, is striking in pistachio ( Pistacia vera L.). Floral buds of pistachio are formed a year before bloom, but abscise during the years with heavy crop (‘on’ year). Abscission of floral buds is due to competition between growing seeds on 1-year-old shoots and developing buds on current season growth. We studied the effects of chemical fruit thinning on alternate bearing and nut characteristics in a commercial orchard of ‘Owhadi’ pistachio cultivar during 2003–2004 in Rafsanjan, Iran. In both years, ethephon (100 and 200 mg l −1 ), naphthaleneacetic acid (NAA) (125 and 250 mg l −1 ) and urea (2.5 and 5%) were applied to the branch units of each individual ‘on’-year trees. The results showed that ethephon at both concentrations significantly increased fruit thinning and floral bud retention for the subsequent year. Other treatments also increased fruit thinning and floral bud retention but were inferior to ethephon.

Determination of fatty acid compositions, oil contents and some quality traits of hazelnut genetic resources grown in eastern Anatolia of Turkey

Located in eastern Anatolia, Bitlis province presents microclimatic conditions for hazelnut cultivation. This microclimatic zone results from the mild effects of Lake Van and Suphan Mountain. With native hazelnut population of 2750 da, Hizan County is surrounded by high mountains, and is a special microclimatic zone where all plantations consisting of thousands of hazelnut plants are native. Bitlis can therefore be said to be rich in wild genetic resources of hazelnut. The aim of this study was to select promising genotypes within the native hazelnut population, describe the desirable nut characteristics, and provide some chemical traits with respect to nutritional values for future breeding efforts. In this study, some nut quality characteristics, protein, ash and oil contents, and fatty acid compositions of 20 Corylus avellana L. genotypes selected from native hazelnut population of Bitlis (eastern Anatolia, Turkey) were described. The hazelnut genotypes showed nut weight in a range from 1.85 to 3.63 g; kernel weight, 0.80–1.46 g; kernel percentage, 32.26–46.11%; shell thickness, 1.20–2.04 mm; nut length, 16.1–23.4 mm; nut width, 15.9–21.0 mm; nut thickness, 12.9–18.5 mm; kernel length, 13.0–18.7 mm; kernel width, 10.3–15.4 mm; kernel thickness, 9.4–12.8 mm; nut shape index, 0.99–1.50; kernel shape index, 0.96–1.73; shrivelled kernel, 0–10%, and double kernels, 0–6%. With respect to nutritional analyses, the hazelnuts contained oil in the range from 57.5% to 74.1%; protein, 15.7–19.2%; ash, 0.79–3.21%; palmitic acid, 4.39–8.85%; stearic acid, 1.67–3.18%; oleic acid, 73.48–81.57%; linoleic acid, 10.46–14.95%; linolenic acid, 0.02–0.34%, and myristic acid, 0.01–0.16%. All genotypes had light-brown colored kernels, and kernel flavor was “medium satisfactory” and “satisfactory”. The findings revealed that some genotypes are promising in nut and kernel characteristics as well as in nutritional value for future breeding efforts.

Evaluation of Morpho-agronomic Variability of Wild and Cultivated Kola (Cola Species Schott et Endl.) in South Western Nigeria

As part of a breeding programme, exploration and systematic selection exercise of kola (Cola spp.) was carried out in Nigeria from the large number of kola populations in the country based mainly on yield and various nut characteristics. The exercise gave rise to a collection of many accessions of the genus including five wild species that are currently being maintained in field genebanks of Cocoa Research Institute of Nigeria (CRIN), Gambari experimental station, Idi-Ayunre, Ibadan. In order to fully exploit the variability in these plants for genetic improvement, the plants were characterized and their morphological variability described. A list of descriptors, developed by International Plant Genetic Resources Institute (IPGRI) for Avocado, with modifications was employed recording 60 descriptors consisting of 33 qualitative and 27 quantitative characters. The characterization data revealed enormous morphological variability among the plants studied and have strong bearing on the taxonomy of the groups. The result also confirmed that the wild species of Cola form a special group with enormous agronomic traits that are yet to be exploited in kola breeding. Wild species identified with high nut and pod numbers, thick indehiscent pods and fruit size uniformity is recommended for use in interspecific hybridization programme.

Relationships among Nut Characteristics in the Important Hazelnut Cultivars

Relationships among Nut Characteristics in the Important Hazelnut Cultivars

Selection of late leafing, late flowering, laterally fruitful walnut (Juglans regia) types in Turkey

In many areas of Turkey, walnut (Juglans regia) production is limited not only by winter cold but also by autumn and spring frosts that can damage the sensitive non‐dormant tissues. This study was conducted to select late leafing and late flowering walnut types with high lateral fruitfulness within a seedling population in 1999–2001. The main objective of the selection programme was to select types that would not suffer injuries from late spring frost. As a result of the expeditionary observations 19 forms were selected, according to characteristics of late leafing, lateral fruitfulness, blight resistance, anthracnose, and codling moth tolerance. Then, selected forms were further evaluated according to nut characteristics after detailed analysis. The percentage of lateral fruitfulness of selected types was between 10% and 70%. The times of leafing of selected types were 10–20 days later than adjacent types.

Effect of hydrogen cyanamide (dormex), volk oil and potassium nitrate on budbreak, yield and nut characteristics of pistachio (Pistacia vera L.)

SummaryInadequate chilling may delay normal blooming and severely reduce yield of pistachio trees in sub-tropical regions. The present study was conducted in a commerical orchard in Shahmiran, in the south west of the Kerman province of Iran. Hydrogen cyanamide (“dormex” at 0, 1.5 and 3%), volk oil (0, 3.5 and 7%) and potassium nitrate (0, 1.5 and 3%) were applied to branch units of pistachio trees in 2002 and 2003. These treatments, plus combinations of dormex and volk oil, volk oil and potassium nitrate, and 7% volk oil were applied 4 and 8 weeks before normal budbreak (January 5 and February 4). The chemicals were sprayed on two branches of ‘Ahmad-aghaei’ trees during the two years of study. Treatments with hydrogen cyanamide (dormex), volk mineral oil and combinations of dormex and volk oil, volk oil and potassium nitrate brought forward budbreak by 15 to 20 days compared with controls, and significantly increased yield of the treated branches, dehiscence of nuts and reduced the blank percentage of pistachio nuts of cultivar Ahamd-aghai. Higher concentrations of dormex and volk oil, in the second application (February 4) and combinations of dormex and volk oil were more effective in increasing the yield per branch. The best treatment was dormex 4%, plus volk oil 7%, during the second application. Potassium nitrate (1.5 and 3%) had no significant effect on yield, dehiscence or blank percentage of pistachio nuts. The results of this study might be applicable to pistachio growing regions with a mild winter.

INVESTIGATIONS ON MORPHOLOGICAL AND POMOLOGICAL CHARACTERISTICS OF CHESTNUT GENOTYPES IN IKIZCE AND SENBOLLUK NATURAL AREAS OF ORDU VICINITY

This study has been carried out to contribute to the conservation of natural plant genetic resources and to determine the morphological and pomological characteristics of chestnut genotypes in Ikizce and Senbolluk natural areas of Ordu vicinity. For this aim, morphologic characteristics such as lower and upper leaf surface colour, leaf surface brilliance, leaf pubescence, leaf stalk length, leaf length and wideness were investigated. Nut and kernel weight, nut size, nut height, length and width, colour, brightness, thickness and hardness of nut shell, kernel colour, testa peeling and taste status were also investigated as nut characteristics. The lower and upper leaf surface colour of nut genotypes varied from intense green to clear green. The leaf surfaces varied from bright to mat, the leaf stalk lengths from 8.8 to 19.4 mm, leaf length from 145.0 to 237.6 mm, leaf wideness from 42.6 to 82.0 mm. Average nut weight varied between 1.83- 11.45 g, kernel weight between 1.34-9.71 g, nut width between 11.37-21.41 mm, nut length between 18.79-35.28 mm, nut height between 17.13-30.88 mm, shell colour between typical chestnut colour and intense colour, shell thickness between 0.28-0.58 mm, testa peeling between very easily and difficult, kernel colour between clear and dirty yellow.

Effect of Japan Sea Climate on Geographic Distribution of Castanopsis sieboldii and C. cuspidata

The geographic distributions of Castanopsis sieboldii and Castanopsis cuspidata overlap each other on the Pacific coast of Japan, but on the Japan Sea coast C. sieboldii tends to dominate at similar temperatures. The authors attempted to explain this phenomenon by analyzing the effects of climatic factors. Nuts were collected from the Pacific and Japan Sea coasts of the Kinki and Chugoku districts, and the nut characteristics and the number of layers of epidermis in the leaves of the seedlings were investigated. The distribution of C. sieboldii and C. cuspidata was satisfactorily explained by a multiple regression equation that was developed using three climatic factors: maximum snow depth in winter, lowest temperature in the coldest month, and annual mean temperature, out of fourteen such factors that were considered. The estimated distribution of C. sieboldii and C. cuspidata from the multiple regression equation agreed with 66.2% of the actual observations.

Fruit characterization of Cocos nucifera L. (ARECACEAE) cultivars from the Pacific coast of Costa Rica and the Philippines

Tall coconut cultivars from the Pacific coast of Costa Rica and the Philippines (San Ramon, Tagnanan, and Laguna), were evaluated for fruit characteristics. Most of the introduced cultivars showed extremely large heterogeneity. A cluster analysis, based on the Ward method, classified the palms into four groups with high internal homogeneity. Some of the evaluated coconut palms from the Costa Rican Pacific area had nut characteristics similar to the San Ramon and Tagnanan palm groups but not to the Laguna group. At the association level used (semipartial R2 = 0.10), another group which included the remaining palms sampled from the Costa Rican Pacific coast was constituted.

The effects of apple mosaic ilarvirus (ApMV) on hazelnut (Corylus avellana L.)

SummaryThe effect of apple mosaic ilarvirus (ApMV) on hazelnut cv. Negret was determined by comparisons over seven years of growth, yield and nut characteristics of virus-free trees and trees infected by grafting. Trunk circumference measured every year in winter showed no significant differences in vigour. However, the yield obtained from healthy trees in four years was 77% higher than from ApMV infected trees. This difference was mainly due to the production of more nuts and not to differences in nut weight. The percentage of nuts with brown spot in the kernel cavity was significantly higher for healthy trees, and no differences in the relative number of blank nuts and fatty acid composition of kernel were found. Natural spread of ApMV from infected to healthy trees was not detected by the ELISA test or by visual observation of symptoms seven years after orchard planting.

EFFECT OF WEATHER FACTORS ON COCONUT AND COP PRODUCTION IN KERALA, INDIA

Studies made on the constituents of the coconut fruits harvested from West Coast Tall coconut palms grown under rainfed conditions during the different seasons of the year identified as hot weather season from March to May, southwest monsoon season from June to August, North east monsoon season from September to November and cold weather season from December to February in Kerala, India have indicated that the fruits harvested during the hot weather season arc smaller in size but more in number than those harvested during the other seasons of the year. They have low husk content but more kernel content resulting in more copra content per nut. Shell content also is high in these nuts. In the case of fruits harvested during other seasons of the year the number of nuts obtained is low. They are larger in size and have more husk content but less kernel and copra content per nut. The nut characteristics arc very much influenced by the weather conditions prevailing during the twelve month period of development from the fertilized flower to the mature nut. The studies also show that the effects of the season are not operating in the same way or to the same extent on the different constituents of the fruit like husk, kernel, shell and copra. This is evident from the variation in the constituents of the fruit. The data indicate that maximum output of kernel, shell and copra are obtained from the palms during the hot weather season.

Evaluation of Pecan [Carya illinoinensis (Wangenh.) K. Koch] Germplasm Collections and Designation of a Core Subset

Most plant scientists are aware of the rapid loss of biological diversity in particular habitats, such as Ecuador or Brazil. We often associate the threat to biodiversity with places where the situation is extreme. Even in extreme situations, opinions vary concerning appropriate management to preserve genetic resources (Fearnside, 1989, 1993; Long, 1992; Stepney, 1990). The subject often degenerates into a debate concerning whether to take the “holistic approach” to conservation and attempt to save everything, or to take a “marketplace approach” that values only what sells (Namkoong, 1992). To avoid crisis situations, we must manage our genetic resources wisely, recognizing that future generations are impacted by our decisions. To accomplish that objective, we must see through the oversimplification represented by the extreme management alternatives. Plant genetic resources can be characterized within the context of geographic origin, and reasonable strategies to maintain, develop, and use them can be devised. The National Plant Germplasm System (NPGS) provides a national framework for a portion of that work, in relation to selected crop plants and their relatives. Traditionally, the NPGS has pursued the strategy of ex situ conservation to increase access to plant material for systematic evaluation, maintenance, and dissemination to users. Repositories of the NPGS were recently requested to address suitability of the core concept as a management tool. The core concept, as elucidated by Brown (1989), is a series of management decisions for subdividing genetic collections. The primary justifications for creating the core subset are to 1) make the diversity of the collection more quickly and completely accessible to germplasm users; 2) reduce the number of accessions needed to develop testing procedures, while maintaining confidence that the reduced sample size encompasses the total collection variability; 3) facilitate evaluation and genetic characterization of the collection; and 4) facilitate general management. We assessed the core concept to determine if it would be a useful management tool in the evaluation and management of collections in the National Clonal Germplasm Repository for Pecans and Hickories. This repository was designated in 1984. However, the collection of pecan cultivars that forms the basis of the repository was begun in the 1930s by Louis Romberg. He actively acquired pecan cultivars as parents for use in controlled crosses in the early pecan breeding program. Over the years, cultivars have been acquired as they were deemed useful for the breeding program. The Pecan Crop Advisory Committee has recognized the need to increase genetic diversity in the collection, while maintaining the utility of the collection for use in the breeding program. The strategy undertaken differentiates the pecan collection into two groups: the cultivar collection and the provenance collection. The cultivar collection is composed of selected cultivars propagated by the pecan industry, historically and currently. This collection is maintained as grafted trees in several orchards at Brownwood, Texas, with some duplicates maintained in orchards near College Station, Texas. Since most pecan cultivars can be recognized on the basis of nut characteristics, nut samples are maintained as voucher specimens for individual trees in the

Mechanical Fruit Thinning Influences Fruit Quality, Yield, Return Fruit Set, and Cold Injury of Pecan

Pecan [Carya illinoinensis (Wangenh.) C. Koch] fruit were thinned from `Mohawk' trees in Oklahoma and `Giles' trees in Kansas with a mechanical trunk shaker. All trees bore an excessive crop load before shaking. Fruit thinning improved the kernel percentage, individual nut weight, and kernel grade of `Mohawk', but nut characteristics of `Giles' were not affected by fruit thinning. Cold injury, caused by a sudden temperature drop in November, was positively related to the percentage of fruiting shoots in both cultivars. Fruit set in 1992 was negatively related to the percentage of fruiting shoots in 1991 in both cultivars. Consistent annual fruit set could be induced in `Giles' by fruit thinning, but return fruit set in `Mohawk', even at high levels of thinning, was low. Fruit thinning reduced yield the year of thinning in both cultivars. Thus, `Mohawk' trees should be thinned so that 50% to 60% of shoots bearing fruit at mid-canopy height would remain, and `Giles' trees should be thinned similarly to 65% to 70%.

Heritability and Phenotypic Correlations of Six Pecan Nut Characteristics

Heritability estimates for pecan [Carya illinoinensis (Wangenh.) K. Koch] nut weight, nut buoyancy, nut volume, nut density, kernel weight, and percentage kernel were determined from 8748 nut samples representing 152 families collected during 25 years in the U.S. Dept. of Agriculture (USDA) pecan breeding program at Brownwood, Texas. Measurements were corrected for year-to-year environmental variability using least-squares constants of individual year effects. Adjusted values were then regressed on midparent means. Generally, heritability (h2) estimates were low to moderate: nut weight 0.35, nut buoyancy 0.18, nut volume 0.35, nut density 0.03, kernel weight 0.38, and percentage kernel 0.32. The low values are probably due to the extreme alternate bearing tendency of this species, since crop load affects pecan nut characteristics so directly. Phenotypic correlations among these traits showed that larger or heavier nuts had significantly higher kernel weight, buoyancy, and percentage kernel. Nut density increased with higher nut and kernel weight, but decreased with nut volume.

Selective Limb Pruning Intensity Influences Mature Pecan Tree and Nut Characteristics

Pecan [Carya illinoensis (Wangenh.) C. Koch] tree height was gradually reduced by removing one, two, or three limbs per year at a height <9 m. Pruning improved tree vigor and color, increased trunk circumference, terminal shoot growth, nut size, and leaf N, P, and Mg, but reduced leaf K and percentage of fancy grade kernels relative to unpruned trees. Yield was not influenced by selective limb pruning.

Tree Yield and Nut Characteristics of Pecan with Drip Irrigation under Humid Conditions1

Abstract Drip irrigation on 1 and 2 sides of pecan [Carya illinoensis (Wang.) Koch.] trees was programmed to irrigate when soil water suction 61 cm from the emitter was greater than 0.1 bar at either 15, 30, or 45 cm depth. Results were compared with no irrigation. The data indicate little advantage of 2 lines of emitters over one line when the same number of emitters/tree are used. The data often favored 1 line over 2 lines. Total yield of pecans was increased substantially by drip irrigation on one side (‘Desirable’ and ‘Elliott’) or both sides of the tree (‘Elliott’), but increases from ‘Farley’ were not significant. In 1968, an extremely dry year, ⅓–½ of the shucks did not dehisce completely on nonirrigated trees while 1 to 7% of the shucks did not dehisce on irrigated trees. Irrigation increased nut size. Percentage kernel was increased by irrigation in 1968 but not in other years. In 1968, percentage fancy kernels was almost doubled by irrigation for ‘Desirable’ but was reduced for ‘Elliott’.