Pecan Research Articles

Enhancing Soil Fertility and Elevating Pecan Fruit Quality through Combined Chemical and Organic Fertilization Practices

This study focused on 6-year-old ‘Pawnee’ pecan trees to elucidate the differential responses of physicochemical properties of orchard soil and pecan fruit quality when combining chemical and organic fertilizers. The aim was to unveil the mechanisms that underlie the effects of different fertilization treatments on soil fertility, soil enzyme activities, and pecan fruit quality. Four treatments were established: sole chemical fertilizer (CF; N:P2O5:K2O is 15:15:15), chemical fertilizer combined with cake fertilizer (CF+CC), chemical fertilizer combined with manure fertilizer (CF+M), and chemical fertilizer combined with cake and manure fertilizer (CF+CC+M). Measurements were taken to assess the soil nutrient content, soil enzyme activities, and fruit growth quality in some orchards under different fertilization treatments. The results revealed that the combined application could increase yield and enhance pecan quality. Among these, the CF+M+CC treatment demonstrated the most favorable outcomes, with the pecan kernel oil and unsaturated fatty acid contents reaching 72.33% and 97.54%, respectively. The combined fertilization treatments had no significant impacts on soil trace elements such as Mg, Cu, and Mn; however, it significantly increased the Available Phosphorus (AP), Total Nitrogen (TN), Soil Organic Matter (SOM) and S-ACP (soil acid phosphatase) activities. In summary, the combined application of chemical and organic fertilizers can significantly increase the soil nutrient content and enzyme activities in pecan orchards, to promote the enhancement of fruit quality and economic aspects.

Carya illinoinensis (Juglandaceae), new to the Italian alien woody Flora and second record for continental Europe

AbstractA woody alien species, Carya illinoinensis (Juglandaceae), is found in Rome (central Italy) along banks of river Tevere. The discovery represents the first record for Italy and the second one for the continental Europe. Description, distribution in Italy, phenology, and original photographs are provided. Moreover, the name Juglans illinoinensis (basionym of C. illinoinensis) is lectotypified on a Wangenheim's illustration (Table XVIII, Figure XXXXIII).

Revealing microbial patterns in the rhizosphere of pecan trees asymptomatic and symptomatic for Texas root rot using a high-throughput sequencing approach

The rhizosphere harbors diverse microbial communities that play crucial roles in nutrient cycling and plant health. Understanding the composition and dynamics of these communities is essential for optimizing agricultural productivity and disease management. In this study, bacterial and fungal communities in the rhizosphere of pecan trees (Carya illinoinensis) asymptomatic and symptomatic for Texas root rot were characterized using high-throughput sequencing of the 16S rRNA gene and ITS region. The results indicated that Proteobacteria and Actinobacteria were the predominant bacterial phyla in both conditions. The predominant fungal phyla comprised Basidiomycota and Ascomycota in symptomatic conditions and Ascomycota and Mortierellomycota in asymptomatic ones. At the genus level, Streptomyces and Pseudomonas were the most abundant bacterial genera; among fungi, Scleroderma and Psathyrella were predominant in symptomatic samples and Mortierella in asymptomatic samples. α-diversity analysis showed significant differences in the fungal community. Specific bacterial and fungal biomarkers for asymptomatic and symptomatic conditions were identified, highlighting their importance in the pecan tree rhizosphere. A total of six bacterial and seven fungal taxa were detected in symptomatic samples, while four bacterial and 16 fungal taxa were detected in asymptomatic ones. These included genera known for their roles in soil health, such as Pseudomonas, Kaistobacter, Streptomyces, Psathyrella, Scleroderma, and Mortierella. Co-occurrence network analysis revealed higher complexity and interaction levels among microbial communities in asymptomatic samples, suggesting a healthier network supporting microbial communities. This study provides comprehensive and valuable insights into microbiome dynamics and microbial resources for future studies aimed at improving agricultural production through the study of rhizosphere microorganisms.

Further data on the establishment of Coptodisca lucifluella (Clemens, 1860) (Lepidoptera: Heliozelidae) in Romania

AbstractFollowing its first report in Romania in August 2022, more data regarding the walnut shield bearer Coptodisca lucifluella was collected. The leafminer moth is an invasive species of North American origin that entered Europe in 2010 (in Italy), and then spread to Hungary, Ukraine, Bulgaria and Romania. It is not an economically important pest alone but in association with other stresses affecting walnut trees, over time, it could contribute to their premature decline. In Romania, C. lucifluella was identified in 24 localities in eight counties and in Bucharest. The main host is the common walnut, Juglans regia (L.), while secondary hosts include the black walnut Juglans nigra (L.), Caucasian walnut Pterocarya fraxinifolia (Lam.) Spach and the pecan nut tree Carya illinoinensis (Wangenh & K. Koch). All walnut trees inspected in 2022 were affected by the leafminer to a greater or lesser extent. The proportion of attacked leaves per tree, evaluated in Northern Bucharest and Moara Domnească in the south of the country respectively, was 40% and 41% in August and increased to 69 and 93%, in October. Inside the mines, our team discovered a significant number of parasitoid larvae and pupae. These were kept in the laboratory until the emergence of adults which were photographed, but so far remain unidentified. The rate of parasitism was 17.4% in N. Bucharest and 31.8% in Moara Domnească.

Highly efficient natural deep eutectic solvent-based liquid-liquid microextraction and inductively coupled plasma mass spectrometry for selective determination of inorganic selenium species in nut samples

A novel method involving the use of a hydrophobic natural deep eutectic solvent (NADES) in the vortex-assisted liquid-liquid microextraction technique based on the solidification of floating NADES for inorganic Se speciation analysis was developed. In this work, Se(IV) species was selectively complexed with ammonium pyrrolidinedithiocarbamate (APDC) and extracted with 50 μL of the NADES thymol:decanoic acid (THY:DA) (1:2) followed by fast phase separation upon freezing. Se(VI) species remaining in the aqueous phase was directly determined by inductively coupled plasma mass spectrometry (ICP-MS) while total inorganic Se concentration was determined by direct analysis of the acidic extract originated from the samples. Therefore, Se(IV) was calculated by subtracting the concentration of Se(VI) from the total inorganic Se concentration. Extraction conditions such as pH, sample volume, and type and volume of NADES were optimized, yielding an extraction efficiency of 99.6% for Se(IV). Limits of detection of 0.31 μg L−1 for Se(IV) and 0.24 μg L−1 for Se(VI), relative standard deviations of 3.5% for Se(IV) and 3.0% for Se(VI) and a linear range of 0.78–1000 μg L−1 were obtained. This work reports the first application of the NADES THY:DA (1:2) for the separation and determination of Se species in complex matrix samples such as almond, hazel nut, peanut, walnut, cashew nut, pecan nut and Brazil nut.

Variation in pigments in pecan testa during kernel development and storage

The pecan (Carya illinoinensis) is an important tree nut worldwide. Browning of the testa during storage considerably reduces its quality. However, the pigments that cause browning and their accumulation patterns are poorly understood. We analyzed the color changes in the testa during the five developmental stages of the kernel after storage at room temperature to compare differences in their color and identify the pigments. Samples exhibiting different colors along with their corresponding −80 °C storage samples were selected for metabolomic analysis. A total of 591 phenolic compounds were detected, 52 phenolics showed regulatory effects on testa discoloration, and 59 metabolites were identified as possible precursors of the pigments. This study revealed the most thorough phenolic composition of pecan to date. Further, the findings provide new insights into the mechanisms of testa browning, deepens our understanding of the bioactive value of pecans, and contributes to the breeding of less browning-susceptible varieties.

Canopy hedge pruning in pecan production differentially affects groups of arthropod pests and associated natural enemies

Controlling canopy growth and size through pruning techniques in perennial agroecosystems is often crucial to maximizing productivity. However, the implications of modifying canopy architecture for arthropod management are often overlooked. We studied the effects of hedge pruning on pests and natural enemies on mature pecan trees by assessing the abundance of: 1) leaf-dwelling aphids and mites, 2) visually detectable injuries caused by black pecan aphids [Melanocallis caryaefoliae (Davis)] and Phylloxera spp., 3) aphid parasitoids and parasitized hosts (aphid mummies), and 4) predatory mites. Additionally, we assessed the prevalence of entomopathogens that dwell on the orchard floor, under the trees. Hedge pruning decreased Phylloxera infestation but increased pressure from scorch mites and the yellow aphid complex. Black pecan aphid abundance responded inconsistently, but their damage was consistently reduced in hedged canopies. Predatory mites were only affected by hedging in the second year when higher populations were observed. Although parasitoid wasp abundance was not affected by hedging, more parasitized aphids (mummies) were observed in trees that did not receive pruning in the first year. Also, higher activity of entomopathogens was observed in soil cores collected under hedged trees in the first year but lower in the second. Taken together, the effects of hedge pruning pecan canopies were case-specific, and cannot be generalized across pests or natural enemies. Nevertheless, structural and environmental variation across seasons and within hedge pruning systems clearly have implications for crop protection in pecans and other perennial systems.

Insertion/deletion variant characterization and marker development in pecan [Carya illinoinensis (Wangenh.) K. Koch

Pecan is an economically important tree worldwide. However, limited insertion/deletion (InDel) molecular markers are available for this species, which hinders molecular breeding and genetic improvement. In the present study, 112 publicly available transcriptome datasets corresponding to 784 Gb nucleotides were mapped against pecan reference genome for InDel identification. A total of 27,503 InDel loci were detected and found to be unevenly distributed across 16 chromosomes. Among them, 18,805 were located within genic regions, while the remaining 8,698 were situated at non-genic areas. There were 9,307 InDel-associating genes, accounting for 28.84 % of total genes. Out of the InDel-containing genes, 2,548 showed exon variations, and these genes were over-represented in the pathways of ‘defense response’ and ‘signal transduction’. A total of 275 markers were developed based on the flanking sequences around InDel loci, of which, 197 (71.64 %) produced unambiguous and polymorphic bands when screening eight pecan cultivars. For these polymorphic markers, 34 were selected to reveals the genetic relatedness among 34 pecan accessions. The dendrogram resulting from cluster analysis revealed that genetically close lines were generally grouped together. To rapidly and cost-effectively distinguish pecan collections, four multiplex PCR were conducted using 12 InDel markers. The multiplex PCR products could be resolved by agarose gel electrophoresis and allowed the discrimination of 29 pecan lines. The InDel loci and markers obtained here will help for the effective use of pecan germplasms in the future.

Cytotoxic, antioxidant, and cytoprotective properties of polyphenol‐enriched extracts from pecan nutshells in MDA‐MB‐231 breast cancer cells

AbstractPhenolic compounds present in plants have demonstrated several biological properties such as antioxidant, antitumor, cardioprotective, and antiproliferative. On the other hand, doxorubicin, a chemotherapeutic widely used to treat breast cancer, usually exhibits chronic cardiotoxicity associated with oxidative stress. Therefore, we aimed to study the effects of phenolic compound‐enriched extract (PCEE) with doxorubicin in breast cancer. To achieve this, after an SPE‐C18‐column purification process of crude extracts obtained from pecan nutshells (Carya illinoinensis), the resulting PCEE was used to evaluate the cytotoxicity and antioxidant properties against the human breast cancer cell line MDA‐MB‐231 and the normal‐hamster ovary cell line CHO‐K1. PCEE was selectively cytotoxic against both cell lines, with an IC50 value (≈26.34 mg/L) for MDA‐MB‐231 lower than that obtained for CHO‐K1 (≈55.63 mg/L). As a cytotoxic mechanism, PCEE inhibited cell growth by G2/M cell cycle arrest in MDA‐MB‐231 cells. Simultaneously, the study of the antioxidant activity showed that PCEE had a cytoprotective effect, evidenced by reduced ROS production in cells with oxidative stress caused by doxorubicin. The results highlight PCEE as a potential antitumor agent, thus revaluing it as an agro‐industrial residue.

Identification of Fatty Acid Components and Key Genes for Synthesis during the Development of Pecan Fruit

Carya illinoinensis (Wangenh.) K. Koch, a species native to North America, is one of the most famous fruit oil trees worldwide. Fatty acids are essential energy storage substances in the human body. Transcriptome sequencing of pecan kernels was used to screen the key genes of fatty acid synthesis in pecan fruit development. The dynamic changes in the fatty acid fractions of the pecan kernels in different periods were analyzed using GC-MS. This study shows that oil accumulation in seeds follows an ‘M’-shaped bimodal curve, according to the proportion of fatty acid components, from big to small, for oleic acid, linoleic acid, palmitic acid, stearic acid, and linolenic acid. A total of 83.82 Gb of clean data was annotated using the RNA-seq of pecan fruits at distinct stages after flowering, 5376 new genes were discovered, and 2761 new genes were annotated in at least one database. SAD and FAD2 were significantly upregulated at 80–95 and 95–110 days, and downregulated at 110–130 days after flowering. These differently expressed genes (DEGs) were enriched in fatty acid biosynthesis, elongation, and concentration. This study aims to reveal the pecan high-oil synthesis mechanism of unsaturated fatty acids for the genetic improvement of pecan in potential genetic resources in order to promote the work of breeding pecan.

Comparison of the metabolic profile of pecan nuts cultivars [Carya illinoinensis (Wangenh.) K. Koch] by NMR spectroscopy

Pecan nuts (Carya illinoinensis (Wangenh.) K. Koch) contain the highest number of phytochemicals of all nuts, are a natural source of unsaturated fatty acids and other nutrients and can be considered an important addition to the Mediterranean diet al.though several studies have been carried out on pecans, employing several analytical techniques, no systematic study of the metabolic profile is available in literature. In this study, the metabolic profile of pecan nuts of three different cultivars was analysed by Nuclear Magnetic Resonance Spectroscopy. The cultivars compared were Wichita, Stuart, and Sioux, all grown in Italy in the same pedoclimatic conditions. 31 metabolites were identified and 28 were quantified and the three species were differentiated based on multivariate PCA analysis. The differences among them, and the levels of scutellarein and GABA, in particular, were attributed to the adaptation of the plants to the climate in their original areas.

The Herbicidal Activity of Nano- and MicroEncapsulated Plant Extracts on the Development of the Indicator Plants Sorghum bicolor and Phaseolus vulgaris and Their Potential for Weed Control

Weeds decrease yield in crops through competition for water, nutrients, and light. Due to the circumstances mentioned above and the challenge of the emergence of herbicide-resistant weeds, developing sustainable alternatives becomes imperative. Plant extracts formulated into nano- and micro-encapsulates (NPs) emerge as a viable option for weed management. The objectives of this study were to identify phytochemical compounds within the ethanolic extracts of Carya illinoinensis, Ruta graveolens, and Solanum rostratum; determine their pre-emergence herbicidal activity on the indicator plants Sorghum bicolor and Phaseolus vulgaris; produce and characterize NPs with plant extracts; and assess their phytotoxicity under greenhouse conditions. The extracts were provided by Greencorp Biorganiks de México. Phytochemicals were identified through colorimetric assays and HPLC-MS, while pre-emergence tests were conducted in vitro, assessing concentrations of 12.5, 25, and 50% for each extract. NPs were synthesized using the ionotropic pre-gelation method, with size, zeta potential, and encapsulation efficiency (EE) being characterized. Finally, post-emergence tests were carried out in a greenhouse with seedlings. Compounds belonging to the hydroxycinnamic acid, flavonol, methoxyflavonol, hydroxybenzoic acid, methoxyflavone, tyrosol, stilbene, and lignan families were identified in all extracts. The pre-emergence herbicidal activity was observed for all extracts, with germination percentages ranging from 0 to 41% in both indicator plants. NPs exhibited sizes between 290 and 345 nm, zeta potentials ranging from −30 to −35 mV, and EE up to 94%. Finally, enhanced herbicidal activity was observed with plant extract NPs, with the species S. bicolor being more susceptible. NPs containing plant extracts are a viable option for bioherbicide production; however, continued research is necessary to refine formulations and enhance efficacy.

Overcoming dormancy of pecan trees in mild winter conditions

This study aimed to determine chill accumulation to overcome endodormancy of pecan trees using the biological method. Cuttings of isolated nodes in different months and their exposure to natural chill under field conditions were used. The experiment was carried out using seven pecan cultivars: Barton, Mohawk, Jackson, Success, Desirable, Farley and Melhorada (Pitol 1), planted in orchards in the municipality of Canguçu, Rio Grande do Sul, Brazil. Every 30 days from June onwards, when 50% of leaves had fallen from trees (phenological stage 95), 20 cuttings per cultivar were collected in each period untill September. They were sterilized and sent to the phytotron for budbreak monitoring. Budbreak average time, time to reach 50% of budbreak and the final budbreak rate were evaluated. Average budbreak time of cultivars showed little variation along collection period. Chill requirement of pecan cultivars ranged from 51 to 369 chill hours (below 7.2 °C) to reach DD50. It was not possible to determine the chill requirement of the studied cultivars. The moment of cutting collection had little influence on average budbreak time and final budbreak rate.

Effects of Truffle Inoculation on Root Physiology and Mycorrhizosphere Microbial Communities of Carya illinoinensis Seedlings

Although they are a valuable edible ectomycorrhizal fungus, truffles (Tuber spp.) nevertheless face significant difficulties in the development of their scale. As a type of high economic value nut-like economic forest tree, the pecan (Carya illinoinensis) serves as a natural host for truffles. However, the technology for mycorrhizal synthesis in pecan has not yet been developed, and it is still unclear how certain microbes affect this process. In this study, we inoculated the pecan root system with a suspension of truffle spores and investigated the growth physiology of pecan seedlings with various infestation levels, as well as changes in the soil’s physicochemical properties and the makeup of the microbial community at the root level. The findings showed that tuber inoculation significantly increased the peroxidase activity of the pecan root system, significantly decreased the pH, and effective phosphorus content of mycorrhizosphere soil, while increasing the nitrate nitrogen content, and significantly increased the abundance and diversity of the mycorrhizosphere soil fungal community. Different groups of fungal and bacterial markers were formed in the mycorrhizosphere of pecan seedlings at different levels of infestation. In the highly infested group, Rozellomycota and lasiosphaeriaceae were the difference marker fungi, and Xanthobacteraceae, Rhizobiaceae as well as Streptococcaceae were the difference marker bacteria. In the low-infestation group, sphaerosporella was differential marker fungi, and Bacillus and Tumebacillus were differential marker bacteria. The fungal marker flora of the control group consisted of Chaetomium and Gilmaniella. Pseudomonas was the marker bacterial community. Additionally, these fungi included Collarina and Rozellomycota, and several bacteria from the genera Pseudomonas, Gemmatimonas, and others showed highly significant relationships with changes in soil pH, effective phosphorus, and nitrate nitrogen. In conclusion, pecan–truffle mycorrhizal seedlings have the potential to create the ideal microbial community structure needed for mycorrhizal growth, and these microorganisms have the potential to significantly alter the pH, effective phosphorus content, and nitrate nitrogen concentration of the mycorrhizosphere soil. Our results contribute to the understanding of how the mycorrhizosphere microbial community evolves when exogenous mycorrhizal fungi infest host plants and can offer some theoretical guidelines for growing pecan–truffle mycorrhizal seedlings.

Genome-wide identification of the Carya illinoinensis bZIP transcription factor and the potential function of S1-bZIPs in abiotic stresses

Genome-wide identification of the Carya illinoinensis bZIP transcription factor and the potential function of S1-bZIPs in abiotic stresses

Influence of Ripening Process on Pecan Nut (Carya illinoinensis) Kernel Quality: Phenolic Profile, Antioxidant Activity, and Carbohydrate Composition

Pecan nuts (Carya illinoinensis) provide a wide range of bioactive compounds (particularly polyphenols) that improve the nutritional quality of diets. This study aimed to monitor the evolution of polyphenolic compounds (total phenols, total flavonoids, total flavanols, total condensed tannins, and total o-diphenols), the phenolic profile, the antioxidant activity, and the sugar concentration during pecan nut development in three Tunisian cultivars. Condensed tannins (41.98–221.13 mg catechin assay equivalents g−1 FW) were the dominant class of phenolics at all maturity stages, followed by total phenols (12.25–57.92 mg gallic acid equivalents g−1 FW). Ellagic acid and catechin were the most abundant phenolics at all maturity stages. The highest phenolic content and antioxidant activity were found at an early stage of ripening but as maturity progressed, a decreasing trend was observed. Sucrose (6.09–30.79 mg g−1 FW) was the predominant sugar followed by fructose and then glucose. A decreasing and later increasing trend of total carbohydrate concentration was detected during nut development. A Canonical Discriminant Analysis of the data succeeded in separating the three pecan cultivars due to their unique characteristics. Overall, the cultivar and the degree of maturity are the major factors controlling the chemical composition and antioxidant capacity of pecan nuts. This study provides more information on the optimal period when the maximum concentration of these health-enhancing compounds is found for use in food, nutraceutical, cosmetic, and pharmaceutical applications.

Evaluation of Natural Spring Freeze Tolerance of Five Pecan Scion–Rootstock Combinations

Pecan [Carya illinoinensis (Wangenh.) K. Koch] is a member of the Juglandaceae family. During spring, pecan trees break their bud dormancy and produce new leaves and flowers. Carbohydrates stored in roots and shoots are thought to support the bloom and early vegetative growth during this time until new leaves start the full photosynthetic activity. Spring freeze is known for its damaging effects on pecan bud and flower growth and development. Pecan shoots with leaves and flowers from five scion–rootstock combinations were collected hours before and after a recent spring freeze (below 0 °C for 6 hours, 21 Apr 2021, Perkins, OK, USA). Morphologies of the leaf, bud, and catkin were visually observed, and the morphologies of the anther and pollen in paraffin sections were investigated by light microscopy. Soluble sugar and starch from bark and wood were analyzed using the anthrone reagent method. The Kanza–Mount showed the maximum damage to terminal leaves, buds, and catkins, whereas Maramec–Colby had the minimum damage only to leaves. Pollen grains were shrunk and reduced in number in the anthers in the protandrous Pawnee scions, whereas no pollen damage was observed in the protogynous Kanza scion. Furthermore, bark soluble sugar levels increased in all the scion–rootstock combinations after the freeze, which may indicate a physiological response to the cold stress. Overall, the extent of spring freeze damage of pecans is affected by the growth stage, types of scion and rootstock, and the scion–rootstock interactions. Furthermore, in addition to low temperature, scion–rootstock interactions also affected the starch and soluble sugar contents in wood and bark tissues.

Development and validation of sensitive and rapid immunoassays to detect minute amounts of hazelnut in processed food and working surfaces

Hazelnut (Corylus avellana L.) represents one of the most allergenic nuts and it can be found as a hidden allergen in processed food due to cross contamination. Therefore, sensitive and specific analytical techniques are in high demand to be used in allergen risk management plans at food industry. In this study, sandwich ELISA and Lateral Flow Immunoassay (LFIA) to detect hazelnut have been developed based on the determination of Cor a 9, one of the most abundant and allergenic proteins of hazelnut. Results showed that cross-reactivity was only found with walnut and Pecan nut, which was lower than 0.1%. When analyzing food spiked with a hazelnut extract or blended with hazelnut flour, ELISA and LFIA were able to detect 0.1 ppm and 0.5 ppm of hazelnut protein with a recovery from 82 to 110%. ELISA and LFIA could also detect 0.15 and 0.6 ppm of hazelnut protein in baked cookies incurred with ground hazelnut, respectively. Furthermore, LFIA could detect 1.25 μg of hazelnut protein in working surfaces of stainless steel and melamine. The sandwich ELISA was in-house validated, showing acceptable results of precision. Likewise, ELISA and LFIA showed to be robust tests. The combined use of both assays could improve the allergen risk management plans in food industry to monitor the presence of hazelnut traces in raw ingredients, processed food and working surfaces.

Targeted metabolomics reveals key phenolic changes in pecan nut quality deterioration under different storage conditions.

Pecan nuts are highly enriched in phenolic compounds, which contribute to the health benefits of pecans. Phenolic compounds represent the main oxidation reaction substrates, thus leading to quality deterioration, namely pellicle browning or a decrease in beneficial effects during pecan storage. Hence, four different storage conditions were performed for 180 d to simulate real production situations. Targeted metabolomics was chosen to identify the specific phenolic compounds involved in quality deterioration under different storage conditions in 0, 90, and 180 d samples. A total of 118 phenolic compounds were detected, nine of which were identified for the first time in pecan. The total phenolic content (TPC) and antioxidant capacities initially demonstrated high scores, after which they tended to decrease during the storage process. The significantly modified phenolic compounds during storage were selected as the metabolite markers of pecan quality deterioration, including catechin, procyanidin (PA) trimer, PA tetramer, trigalloyl hexahydroxydiphenoyl (HHDP) glucose, and tetragalloyl hexoside. Fresh pecan kernels resulted in more pronounced changes in hydrolysable tannins (HTs), whereas dry kernels resulted in the most accentuated changes in condensed tannins (CTs). To the best of our knowledge, this is the first attempt to study individual phenolic changes during storage of pecan in such massive amounts. The results can offer a valuable theoretical basis for future control of pecan quality deterioration through phenolics during storage.

Do Nonstructural Carbohydrates Contribute to Pecan (Carya illinoinensis) Secondary Budburst?

Spring freeze is among the problems threatening pecan bloom and production. Pecan tree height and structure make them difficult to protect from spring freezes. Some cultivars can compensate because the secondary buds can produce healthy flowers if the primary buds freeze. The mechanism that precipitates secondary budbreak is unknown. Our results show a correlation between successful secondary budbreak and 1-year-old shoot carbohydrate levels. ‘Kanza’ and ‘Pawnee’, with the higher secondary budburst, also had higher carbohydrate levels than ‘Maramec’. This suggests higher carbohydrate levels in the bud-bearing 1-year-old shoots promote successful secondary bud burst after spring freeze destruction of the primary buds.