Nut Set Research Articles

Prediction of bolt fastening state using structural vibration signals

We have proposed a new method to predict the state of bolt fastening connection using time-domain structural vibration signal and experimentally validated its effectivness. To obtain the structural vibration signal, non-contact type laser displcement sensor and contact type piezo film sensor were used, respectively. Two-beam structures with holes were prepared and fastened with a set of bolt and nut. By applying a random initial displacement at the free end of the cantilever beam structure, vibration signals were measured for three different bolt fastening states: fully fastened, half-loosened and 90 %-loosened. After extraction of features from the obtained vibration signals, the bolt fastening state was classified based on the k-nearest neighbor (k-NN) algorithm. It is experimentally verified that the bolt fastening state can be accurately predicted by using the structural vibration signals and machine learning algorithm.

Cross-pollination Enhances Macadamia Yields, Even With Branch-level Resource Limitation

Macadamia is partially self-incompatible and cross-pollination is considered important to improve yields. However, questions remain regarding the importance of self- vs. cross-pollination, and subsequently whether managed pollinators are useful in commercial orchards. Pollinators play a key role in cross-pollination, but for self-pollination, the protandrous florets might also benefit from the movement of potentially more viable self-pollen among florets, racemes, and trees through pollinator movement. There is also a lack of information on pollination deficits throughout orchards and whether by increasing the intensity of cross-pollination, final nut yield is limited by within-tree resource allocation. Using caged and bagged racemes on three cultivars, we found strong evidence for self-pollination, but no evidence that hand moving self-pollen within racemes, between racemes, or between trees improved final nut set. In all cases, hand cross-pollinated racemes yielded significantly more nuts. Hand cross-pollinated racemes also produced significantly more developed nuts than open-pollinated racemes (all racemes were exposed to pollinators). However, by increasing the intensity of hand cross-pollination per tree, we showed that resource allocation probably overinflates these measures of pollination deficit in macadamia. Despite this, our findings point to an opportunity to increase yields through additional cross-pollination, as high-intensity hand cross-pollination of flowering racemes within trees still resulted in increased nut set. Although self-pollination can occur in macadamia, to optimize yield potential, strategies to maximize cross-pollination should be adopted.

Bloom timing of almond cultivars in California

Time of bloom and bloom overlap between cultivars is an important consideration when choosing cultivars for new orchards. Self-incompatible cultivars need good bloom overlap between compatible pollenizers for successful cross-pollination and nut set. Cold rain storms in northern California can lengthen bloom or delay a cultivar's bloom, negatively affecting bloom overlap between cultivars in some years. Under varying weather conditions, planting cultivars with the most coincident bloom reduces this risk. Selecting cultivars for pollenizers that bloom slightly earlier and later than an orchard's main cultivar reduces risk related to poor cross-pollination at any one point in time. Conditions reducing honey bee flight can also result in poor cross-pollination. If early or late blooming orchards are planted, selecting cultivars from within the same full bloom group will help ensure good bloom overlap and cross-pollination. Full bloom time for 34 cultivars in the Chico Regional Almond Variety Trial is reported for twelve consecutive years relative to 'Nonpareil' full bloom.

Variability of initial and final nut set in elite macadamia selections using different pollination methods

Selection for yield in macadamia is a major component of the Australian industry breeding program because of its high economic weighting. Pollination success initially determines the nut set and consequently the yield of a tree. The method of pollination may affect the initial nut set (INS) and final nut set (FNS). Tested genotypes are currently involved in a regional cultivar trial across northern New South Wales and South East Queensland, Australia. Pollinations took place in a high density macadamia orchard containing 12 elite genotypes. Each genotype was pollinated using three methods; autogamous pollination, supplementary cross pollination by hand and natural open pollination. INS was recorded 90 days post pollination and FNS 180 days post pollination on 15 racemes tree-1 with 3 reps for each genotype. Pollination methods varied for both INS and FNS. The most efficient pollination method across genotypes was supplementary cross pollination. Autogamous pollination had low INS and lower FNS and the highest mean abscission rate (83.7%). Supplementary cross pollination can increase nut set and cultivars 'HAES 741' and 'HAES 344' were identified as compatible pollinisers. From the elite selections five genotypes were identified as self-fertile by producing nut set through the autogamous pollination method. The greatest difference between the initial and final nut set was for autogamous pollination. Nut set could be utilised for selection of potential high yielding candidate macadamia cultivars.

Pollination limitation despite managed honeybees in South African macadamia orchards

There is growing demand for pollination services in agricultural production, which contrasts with declines of wild and managed pollinator populations. Macadamia (Macadamia integrifolia) is a mass-flowering crop that depends on pollination services and is increasingly cultivated in South Africa. We studied the crop’s pollination in South African orchards considering variation in landscape context and the spatial arrangement of managed honeybees (Apis mellifera). We conducted pollination experiments and pollinator observations on macadamia trees along a distance gradient from orchard edges that bordered either near-natural or human-modified habitats. In addition, we mapped position and density of honeybee apiaries at orchard-level. Nut set of macadamia trees strongly relied on animal-mediated pollination: pollinator exclusion reduced the initial nut set (3 weeks after pollination) by 80% and the final nut set (15 weeks after pollination) by 54%. Supplemental hand-pollination of otherwise untreated flowers increased initial and final nut set by 66% and 44%, respectively, indicating substantial pollination limitation. The landscape context only weakly affected pollinator visitation to macadamia trees, with reduced visitation closer to orchard edges bordering human-modified habitats. Furthermore, we observed almost no wild pollinator species. Instead, honeybees constituted 99% of all visits, whereby honeybee visitation rates increased with a tree’s connectivity to apiaries. However, neither initial nor final nut was related to visitation rates, and the final nut set was actually reduced where honeybee colony density was high, with a predicted 50% reduction in final nut set between the lowest and highest colony densities. Our study demonstrates a strong pollination limitation in South African macadamia orchards, where managed honeybees fail at delivering the increasing need for pollination services. Indeed, increasing their colony densities may further limit their pollination efficiency. A pollination management that also includes non-Apis managed pollinators and wild pollinators is possibly needed to increase nut set and provide solutions for increasing pollination service demands. In intensive macadamia orchards, this can also necessitate the need for more pollinator-friendly management practices, including habitat restoration and reduced pesticide application.

The Effects of the Insect Growth Regulators Methoxyfenozide and Pyriproxyfen and the Acaricide Bifenazate on Honey Bee (Hymenoptera: Apidae) Forager Survival.

The honey bee (Apis mellifera L. (Hymenoptera: Apidae)) contributes an essential role in the U.S. economy by pollinating major agricultural crops including almond, which depends entirely on honey bee pollination for successful nut set. Almond orchards are often treated with pesticides to control a variety of pests and pathogens, particularly during bloom. While the effects to honey bee health of some insecticides, particularly neonicotinoids, have received attention recently, the impact of other types of insecticides on honey bee health is less clear. In this study, we examined the effects to honey bee forager survival of three non-neonicotinoid pesticides widely used during the 2014 California almond bloom. We collected foragers from a local apiary and exposed them to three pesticides at the label dose, or at doses ranging from 0.5 to 3 times the label dose rate. The selected pesticides included the insect growth regulators methoxyfenozide and pyriproxyfen, and the acaricide bifenazate. We simulated field exposure of honey bees to these pesticides during aerial application in almond orchards by using a wind tunnel and atomizer set up with a wind speed of 2.9 m/s. Experimental groups consisting of 30-40 foragers each were exposed to either untreated controls or pesticide-laden treatments and were monitored every 24 hr over a 10-d period. Our results revealed a significant negative effect of all pesticides tested on forager survival. Therefore, we suggest increased caution in the application of these pesticides in almond orchards or any agricultural crop during bloom to avoid colony health problems.

Effect of fertigation on growth, yield and quality of almond under Kashmir conditions

An experiment was conducted for three consecutive years during 2011–12 to 2013–14 with an objective to improve growth, yield and quality of almond by fertigation. There were seven fertigation treatments laid out in randomised block design with three replications. The results revealed maximum plant height (3.67 m), TCSA of main trunk (101.22 cm2), primary, secondary and tertiary branches (20.51 cm2, 6.66 cm2 and 1.97 cm2), canopy volume (8.21m3), and nut yield (4.94 kg/tree and 5.48 t/ha), leaf nitrogen and potassium content (2.39% N and 1.41%K) with 75% RDF through fertigation (split application of N: K in the ratio of 2/3N: 1/3K at nut set to nut development and 1/3N: 2/3K at kernel filling to maturation stage(T-4). The highest fruit number (2208/tree), however, was recorded with 100% RDF through fertigation (T2). The maximum nut weight and size (2.29 g and 36.51 × 21.45 mm), kernel weight and size (1.48 g and 24.71 × 14.59 mm) were recorded with 50% RDF through fertigation (T5) treatment of almond variety Waris under Kashmir valley condition.

Nut set evaluation in inter-specific almond × peach backcross progenies for self-compatibility selection in almond breeding programme

Self-compatibility was examined in 22 almond samples that were selected based on their generic and physiological characteristics. Polymerase chain reaction was also done with consensus primers. Pollen tube growth and nut set analyses were carried out on partially bagged limbs after self-pollination treatment. In spite of the fact that all genotypes had the S f-allele and pollen tube growth were similar, nut set exhibited an alternate year characteristic that ranged from 16.2% to a maximum of 24.7%. This was the highest treatment after self-pollination. Difference existed between genotypes could be due to the genetic constitution of each genotype, is explored in set that is diminished by inbreeding, which diminish gene aggregation in different members of a progeny. In addition, flower morphology could also influence set in bagged limbs. Furthermore, with regard to flower sterility and bud density in relation to both pollination success and ecological condition availability, these traits must be considered when examining production in self-compatible almond orchards, e.g.,—the impacts accompanying inbreeding and effective autonomous self-pollination.

The Synergistic Effects of Almond Protection Fungicides on Honey Bee (Hymenoptera: Apidae) Forager Survival

The honey bee (Apis mellifera L.) contributes ∼$17 billion annually to the United States economy, primarily by pollinating major agricultural crops including almond, which is completely dependent on honey bee pollination for nut set. Almond growers face constant challenges to crop productivity owing to pests and pathogens, which are often controlled with a multitude of agrochemicals. For example, fungicides are often applied in combination with other products to control fungal pathogens during almond bloom. However, the effects of fungicides on honey bee health have been so far understudied. To assess the effects of some of the top fungicides used during the 2012 California almond bloom on honey bee forager mortality, we collected foragers from a local apiary and exposed them to fungicides (alone and in various combinations) at the label dose, or at doses ranging from 0.25 to 2 times the label dose rate. These fungicides were Iprodione 2SE Select, Pristine, and Quadris. We utilized a wind tunnel and atomizer set up with a wind speed of 2.9 m/s to simulate field-relevant exposure of honey bees to these agrochemicals during aerial application in almond fields. Groups of 40-50 foragers exposed to either untreated controls or fungicide-laden treatments were monitored daily over a 10-d period. Our results showed a significant decrease in forager survival resulting from exposure to simulated tank mixes of Iprodione 2SE Select, as well as synergistic detrimental effects of Iprodione 2SE Select in combination with Pristine and Quadris on forager survival.

Direct Effect of cashew Nut Scarification Associated with Powdery Mildew in the Processing Industry

Cashew powdery mildew disease can reduce on field yield by 100% depending on flowers’ susceptibility. Surviving flowers may still produce nuts that are severely damaged. The impact of this, post-harvest, damage to the processing industry is unknown. Therefore the objective of this experiment was to assess the effect of powdery mildew nut scarification on biometric and industrial processing variables: nut size, weight, nut count, outturn, cutting and peeling time and finally analyze the financial implication of the effect. Thus, raw cashew nuts were randomly sampled and categorized in to five disease score levels (treatments). Ten nuts (replicates) were used for each disease category. Length, thickness, width and weight were measured. Furthermore, from each disease level, two sets of nuts were established. One set for nut count and outturn assessment by cutting test. The other set, for steam boiling, cutting, peeling and other processes quantitatively assessed. A completely randomized experimental design was followed for data analysis. The summary effect was assessed as relative loss in percentage to non diseased nuts. The relative maximum loss due to powdery mildew attack was 41.2% for nut length, 42.9% for nut width, 31.3% for nut thickness and 50% for nut weight. The disease severity increased relative nut count (18.9%) and reduced the total percentage of kernels (20.3%), outturn (21.1%), the industrial yield of white wholes (88.1%), amount of peels (27.6%) and the outturn and nut count based projected income by 9.6%. Three disease based nut categories are proposed for processing improvements. Nut scarification effect on kernel deterioration, seed germination and others is under investigation.

Thermal characteristics of a CNC feed system under varying operating conditions

In high-speed and high-precision feed systems, thermal positioning errors are mainly caused by the non-uniform temperature variations and resulting time-varying thermal deformations under different operating conditions. The research presented here ultimately aims to develop a generic method capable of evaluating the thermal characteristics (such as temperature rise of heat sources, thermal positioning error) of the feed system induced by varying operating conditions (feed speed, cutting load and preload of ball screw). The thermal contact resistance between the balls and the inner and outer rings of supporting bearing is calculated using the Hertzian theory and JHM method. Experiments were carried out on a high-speed feed system experimental bench, and the influences of operating conditions on temperature rises of supporting bearings and ball screw nut were analyzed. Based on a WNN-NARMAL2 model, the relationship between temperature rise of supporting bearings and operating conditions was established. Furthermore, with the temperature of the ball screw nut set to be a moving heat source load, the temperature and thermal deformation distributions of the ball screw were simulated. The work described lays a solid foundation for thermal error prediction and compensation of a feed system under varying operating conditions.

An investigation of quantity discrimination in Clark's nutcrackers (Nucifraga columbiana).

We examined quantity discrimination in the Clark's nutcracker (Nucifraga columbiana), a corvid bird with a strong dependence upon caching and recovering nuts. We presented 2 sets of nuts simultaneously, in 21 different conditions, to see if the nutcrackers could choose the larger of the 2 quantities. The nutcrackers displayed a strong ability to discriminate quantities of nuts. Like other animals tested previously, the nutcrackers' performance decreased as the ratio of the 2 quantities approached 1. Interestingly, at constant distances, the nutcrackers did not have more difficulty with contrasts containing larger quantities. Thus, nutcrackers have a fine sensitivity for discriminating between 2 quantities. We review the relevant literature and explore the possibility that nutcrackers, like some other birds, may have developed a keen ability to discriminate quantities. This ability may have developed as an adaptive specialization to cope with their scatter-hoarding ecology, though the evidence for such a conclusion is mixed.

Temperature distribution and thermal error prediction of a CNC feed system under varying operating conditions

In high-speed and high-precision feed systems, the thermal errors are mainly caused by the non-uniform temperature variations and time-varying thermal deformations under different operating conditions. The research work undertaken herein ultimately aims to develop a generic method which is capable of evaluating the temperature rises of heat sources (such as supporting bearings and ball screw nut) and thermal positioning error of the feed system induced by varying operating conditions (feed speed, cutting load, and preload of ball screw). Experiments were carried out on a high-speed feed system experimental bench, and the influences of operating conditions on temperature rises of supporting bearings and ball screw nut were analyzed. Based on wavelet neural network and NARMA-L2 model, the relationship between temperature rise of supporting bearings and operating conditions was established. Furthermore, with the temperature of ball screw nut set to be a moving heating source load, the temperature and thermal deformation distributions of ball screw under bearings and ball screw nut heat sources were simulated. The experiment and simulation results show that the recommended modeling method can be used to predict thermal positioning errors of feed system with good accuracy. The work described lays a solid foundation of thermal error prediction and compensation in a feed system under varying operating conditions.

The Variations of Quality Characteristics According to Environmental Factors of High Tension Bolt, Nut and Washer Set

Because the fastener tension of high strength bolt, nut, and washer set is subject to the environmental factors such as temperature, humidity and storage period, extreme care should be taken during the joining and storage of such products. In case quality change is anticipated, the parts shall certainly be inspected.

Multidimensional Analysis of S-alleles from Cross-incompatible Groups of California Almond Cultivars

The California almond industry is the largest supplier of almonds [Prunus dulcis (Miller) D.A. Webb] in the United States and throughout the world. Self-incompatibility is a major issue in almond production as it greatly affects nut set. In this study, we determined full-length sequences for alleles Sa - Si, determined the genotypes of 44 California cultivars, and assigned the cultivars to cross-incompatibility groups (CIGs). Newly identified S-alleles led to an increase in the number of CIGs. A pairwise distance tree was constructed using the aligned amino acid sequences showing their similarity. Four pairs of alleles (Sc and Se, Sg and Sh, Sd and Sj, and Sb and Sf) showed high sequence similarity. Because of its simplicity, reproducibility, and ease of analysis, PCR is the preferred method for genotyping S-alleles.

Stigma Development and Receptivity in Almond (Prunus dulcis)

Fertilization is essential in almond production, and pollination can be limiting in production areas. This study investigated stigma receptivity under defined developmental stages to clarify the relationship between stigma morphology, pollen germination, tube growth and fruit set. Light and scanning electron microscopy were employed to examine stigma development at seven stages of flower development ranging from buds that were swollen to flowers in which petals were abscising. Flowers at different stages were hand pollinated and pollen germination and tube growth assessed. Artificial pollinations in the field were conducted to determine the effect of flower age on fruit set. Later stages of flower development exhibited greater stigma receptivity, i.e. higher percentages of pollen germination and more extensive tube growth occurred in older (those opened to the flat petal stage or exhibiting petal fall) than younger flowers. Enhanced stigma receptivity was associated with elongation of stigmatic papillae and increased amounts of stigmatic exudate that inundated papillae at later developmental stages. Field pollinations indicated that the stigma was still receptive and nut set was maintained in older flowers. Stigma receptivity in almond does not become optimal until flowers are past the fully open stage. The stigma is still receptive and fruit set is maintained in flowers even at the stage when petals are abscising. Strategies to enhance pollination and crop yield, including the timing and placement of honey bees, should consider the effectiveness of developmentally advanced flowers.

(229) `Lost Hills' Pistachio—A New and Improved Cultivar

`Lost Hills' is a new female pistachio cultivar that is being released as a potential replacement for `Kerman', the industry standard female cultivar. `Lost Hills' produced substantially higher percentages of split, edible nuts than `Kerman' in 2003 when split percentages for `Kerman' were very poor due to reduced winter chilling, a condition that is likely to be more frequent in the future. Nut size for `Lost Hills' is larger than for `Kerman'. Harvest date is 2–4 weeks earlier than `Kerman', which will permit growers to extend their harvest period and better utilize their harvesting equipment and personnel. Earlier harvest may reduce disease in the northern production areas of California by permitting an earlier harvest before fall rains, as well as reducing navel orangeworm infestations. The cultivar requires less chilling than `Kerman', which improves uniformity of foliation, bloom, nut set, nut fill, and uniformity of nut maturity at harvest in years with insufficient chilling for `Kerman'. This cultivar could increase grower profits by more than 20% above that received for `Kerman'.

(228)`Golden Hills' Pistachio—A Replacement for `Kerman'

`Golden Hills' is a new female pistachio cultivar with improved performance characteristics compared to the standard female cultivar Kerman. `Golden Hills' produces a greater yield and higher percentage of split, edible nuts than `Kerman' while maintaining a similar low percentage of loose shells and kernels. Harvest date is 2–4 weeks earlier than `Kerman', which will permit growers to extend their harvest period and better utilize their harvesting equipment and personnel. Earlier harvest may reduce disease in the northern production areas of California by permitting an earlier harvest before fall rains, as well as reducing navel orangeworm infestations. The cultivar requires less chilling than `Kerman', which improves uniformity of foliation, bloom, nut set, nut fill, and uniformity of nut maturity at harvest in years with insufficient chilling for `Kerman'. Based on all of our evaluations, this cultivar appears to be an exceptional producer and has the potential to increase grower profits by more than 40%.

Macadamia responses to mild water stress at different phenological stages

Mild water stress was imposed on bearing macadamia trees in through-draining lysimeters at various phenological stages. Water was withheld until a xylem water potential (Ψx) of –1.5 to 2.0 MPa was reached, this being maintained by partial water replenishment at 2-day intervals. Flowering, nut set, nut development, yield, and quality responses were assessed to identify critical, stress-sensitive stages. Stress during nut maturation was particularly detrimental to both yield and quality, although stress during floral development and the premature nut drop also had adverse effects. Low yields were due to reduced nut number and smaller nuts. Lower photosynthesis (c. 2 μmol CO2/m2.s) at –1.5 MPa would account for reduced yield and poorer quality during nut maturation when energy demands of active oil accumulation are high. Stress at floral initiation was generally not detrimental.Overall, stress restricted growth. The rate of girth growth was significantly lower when stress was applied during the dormant floral initiation stage. When stress coincided with normal periods of vegetative growth, flushing was delayed until after re-watering when greater foliage production was stimulated. Judiciously imposing mild stress may be used to manipulate macadamia phenology, although it may not necessarily conserve water. Further refinement would be needed to develop stress manipulation as a practical and reliable management tool to achieve higher yields. Water should be applied to alleviate stress during critical stages of nut development and maturation. Mild stress after the current crop is mature, however, is unlikely to be detrimental to macadamia yield or quality. It may, in fact, be beneficial through manipulation of flushing patterns that influence yield.

Insect Damage Estimates for ‘Stuart’ Pecan Nutlets from Nut Set to Shell Hardening in Insecticide-Treated and Untreated Trees

Pecan nut loss due to pecan nut casebearer, Acrobasis nuxvorella Neunzig, damage was significantly lower in the chlorpyrifos-treated, ‘Stuart’, pecan trees (0%) than in untreated trees (16%). Percentage loss due to nut drop from all causes between nut set and shell-hardening was significantly lower in the treated (27%) than in the untreated trees (42%). Treated trees had significantly higher average yield (38 kg/tree) than the untreated (29 kg/tree). Nut size was significantly smaller in untreated (156 nuts/kg) than in treated trees (145 nuts/kg). Monitoring the fate of ‘Stuart’ pecan nutlets from nut set to harvest indicated that the number of nuts/cluster at nut set was often positively correlated with kernel weight at harvest, whereas, nut cluster size later in the season was positively correlated with kernel weight at two orchards and negatively correlated with kernel weight in the control treatment at a third orchard. A commercial orchard where pecan nut casebearer, hickory shuckworm, Cydia caryana (Fitch) and nut curculio, Conatrachelus hicoriae Schoof, were controlled with insecticide sprays in the spring had similar total nut drop over the entire season as an orchard where these insects were not controlled. The majority of the pecans that dropped from the trees did not have discernible signs of plant disease, insect feeding damage or insect oviposition.