bluuebunny/crossref_metadata_2025 huggingface dataset:
ß-Galactosidase II Activity in Relation to Changes in Cell Wall Galactosyl Composition during Tomato Ripening
Authors: Carrington C.M. Sean , Pressey Russell
Published: January 2019

Activity of ß-galactosidase II (EC 3.2.1.23), which can hydrolyze ß-galactan from tomato cell walls, increased markedly during ripening of `Roma' and `Rutgers' tomatoes (Lycopersicon esculentum Mill.). Activity of two other ß-galactosidase isozymes, incapable of galactan hydrolysis, was present in green fruit and remained unchanged throughout ripening. ß-Galactosidase II activity was not detectable in green fruit of either cultivar, appearing first at the breaker stage of `Roma' fruit and not until the pink stage of `Rutgers' fruit. Consistent with this, galactose loss from Na2CO3-soluble pectin (NSP) was detectable at an earlier stage in `Roma' vs. `Rutgers' fruit. A greater decline in NSP galactose was evident in `Roma' fruit compared to `Rutgers' fruit, in keeping with the higher levels and longer period of ß-galactosidase II expression in the former. Significant galactose loss from trans -1,2-diaminocyclohexane-N,N,N',N' -tetraacetic acid-soluble pectin, in contrast, was not seen until the last stage of ripening. These results indicate that the long-reported, net galactosyl loss from the cell walls of ripening tomatoes correlates with ß-galactosidase II activity. Nonetheless, the observation that softening commenced before ß-galactosidase II activity or galactose loss was detectable suggests some other basis for the earliest stages of ripening-related fruit softening in tomato.
Chemical Composition of Lowbush Blueberry Cultivars
Authors: Kalt Willy , McDonald Jane E.
Published: January 2019

The chemical composition of the lowbush blueberry (Vaccinium angustifolium Aiton) cultivars Blomidon, Cumberland, and Fundy were examined at three stages of fruit maturity, before and after refrigerated storage, in a 2-year study. There were differences (P< 0.001) related to maturity and cultivar in berry fresh weight, percentage dry matter, fruit firmness, percentage soluble solids, titratable acidity, and the concentration of sugar, acids, and anthocyanins. Among the nine organic and phenolic acids measured, seven acids varied among the maturity groups and eight varied among the cultivars. Between the 2 years of study there was a 60% difference in total fruit acid content as well as in the relative amounts of each acid. The 2-year mean profile of lowbush blueberry acids was distinctly different from that recently reported for highbush (Vaccinium corymbosum L.) and rabbiteye blueberries (Vaccinium ashei Reade). The level of certain acids as well as the concentration of anthocyanins increased during cold storage. Estimation of sugar concentration by percentage soluble solids overestimated sugar concentration by 3070. Acid measurement by titration underestimated acid content as measured by HPLC by 61%. Results of this study illustrate the variation in the chemical composition of lowbush blueberry fruit among cultivars, maturities, and seasons, and can be used to compare lowbush blueberries with other Vaccinium species.
Fused Vein Trait in Cucurbita pepo L. Associated with Subvitality of the Male Gametophyte
Authors: Carle R. Bruce , Loy J. Brent
Published: January 2019

Two experiments were conducted to test and delineate gametophytic subvitality of the fused vein trait in Cucurbita pepo. Gametophytic subvitality was verified by comparing pollen tube growth for fused vein and normal pollen in situ. Microscopic examination of partitioned, co-pollinated distillate flowers revealed inferior fused vein gametophyte performance. Normal pollen tubes grew faster and were significantly more abundant in the lower portion of the style. The consequences of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of pollen competition. Fused vein, normal and F1 lines were pollinated with fused vein, normal, F and a 50:50 pollen mix at three different pollen loads. Fused vein pollen generated significantly fewer seed per fruit in all female genotypes. As a constituent in F, or mixed pollen, it produced significant seed yield reductions at the low pollen load. In F1 and testcross populations, a reduction in pollen load and therefore pollen competition significantly increased the number of fused vein individuals in segregating populations.
Genetic Variation among Sweetpotatoes Propagated through Nodal and Adventitious Sprouts
Authors: Villordon Arthur Q. , LaBonte Don R.
Published: January 2019

Genetic uniformity was assessed among sweetpotato (Ipomoea batatas) clones propagated through adventitious and nodal procedures. A single sprout each of `Jewel,' `Sumor,' and L87-95 was used as source of clonal plants that were simultaneously propagated through conventional adventitious procedures and a tissue culture-based nodal culture technique. A sample of 15 decamer primers generated 64 scorable amplified fragments in a PCR-based assay, 29 of which were putatively polymorphic across n = 60 samples (10 each of nodal and adventitiously derived plants/genotype). Within adventitiously derived materials, putative polymorphisms ranged from 4.7% to 31.3% depending on the genotypic class. In contrast, putative polymorphisms ranged from 0.0% to 3.1% among nodally derived samples. Marker loci differentiated genotypes as well as putative marker phenotype variants through a multidimensional scaling analysis of the genetic similarity matrix. An `analysis of molecular variance' shows that genotypic effects accounted for 88.7% of the total molecular marker variability, while propagation effects (within genotypic groups) accounted for 11.3%. Results confirm that clonal plants derived from preexisting meristematic regions are more genetically uniform than plants propagated from adventitious origins.
Timing of Pistacia chinensis Bunge. Rooting Using Morphological Markers Associated with Calendar Date and Degree Days
Authors: Dunn Diane E. , Cole Janet C. , Smith Michael W.
Published: January 2019

The objective of this study was to determine the most advantageous time to collect cuttings of Chinese pistache, a commonly recommended ornamental shade tree that is difficult to propagate by cuttings. In 1993, calendar date and degree days (daily mean temperature -7.2C) were used to estimate an appropriate cutting time. The greatest percentage of rooted cuttings occurred in male cuttings harvested on 13 May 1993 (397 degree days) and treated with 17,500 mg·liter-1 IBA or in male cuttings harvested on 20 May 1993 (482 degree days) and treated with either 8750 or 17,500 mg·liter-1 IBA. In 1994, cutting time was associated with calendar days, degree days, and morphology. The most rooted cuttings (44%) were from green softwood cuttings taken on 9 May 1994, which was 380 degree days from orange budbreak using a threshold temperature of 7.2C. Orange budbreak was characterized by separation of the outer bud scales such that the orange, pubescent inner bud scales were visible. Cuttings taken on 9 May 1994 and treated with 8750 mg·liter-1 IBA produced the most primary and secondary roots and the longest primary roots per cutting. Male Chinese pistache cuttings should be collected from green softwood or red semi-softwood stems when about 380 to 573 degree days have accumulated after orange budbreak. Chemical names used: indolebutyric acid (IBA).
New Genes, stp and stphbw, for Flower and Seedcoat Pattern in Common Bean
Authors: Bassett Mark J.
Published: January 2019

The inheritance of novel flower and seedcoat patterns was studied in three parental materials: PI 390775 and `Springwater Half Runner' (SHR), which have patterned flower and seedcoat colors, and 5-593, a Florida dry bean breeding line with unpatterned purple flowers and seeds. Using crosses between 5-593 and the other two parents, an analysis of F1, F2, backcross F2, and backcross F3 data demonstrated that a single recessive allele in each of the patterned parents controlled flower and seedcoat pattern. Genetic tester stocks were used to demonstrate that the recessive gene for patterning in PI 390775 was nonallelic with C, T, and Mar, the three genes previously known to control seedcoat pattern in common bean. An allelism test between the recessive pattern genes from PI 390775 and SHR demonstrated that they were allelic and that the gene from SHR was dominant. The gene symbols stp (for the gene from PI 390775) and stphbw (for the dominant gene from SHR) are proposed, where stp stands for stippled seedcoat pattern and the superscript letters hbw stand for half banner white.
Histology and Origin of Somatic Embryos Derived from Anthurium andraeanum Linden ex André Lamina
Authors: Matsumoto Tracie K. , Webb David T. , Kuehnle Adelheid R.
Published: January 2019

Histological analysis of somatic embryos derived from in vitro-grown lamina of Anthurium andraeanumshowed bipolarity with the presence of shoot and root poles connected by procambium. Vascular connections between the explant and somatic embryos were not observed. Storage of proteins, starch and raphides as well as a suspensor-like structure and an epidermis were observed in the somatic embryos. Origin of the somatic embryos was from a proembryonic cell complex or possibly from a single cell by direct embryogenesis. Both modes of somatic embryogenesis arose from the mesophyll.
Viability and Vigor of Osmotically Primed Muskmelon Seeds After Nine Years of Storage
Authors: Oluoch Melkizedek O. , Welbaum Gregory E.
Published: January 2019

The viability and vigor of osmotically primed (0.3 m KNO3, 6 days, 25C) and nonprimed `PMR 45' muskmelon (Cucumis melo L.) seeds were compared after storage for 9 years at <20C and 6% moisture content (MC, dry weight basis). Viability was compared at 20, 25, and 30C at water potentials of 0, -0.2, -0.4, -0.6, and -0.8 MPa and in soil. Additionally, stored primed and nonprimed seeds were either primed, aged (15% MC and 45C) for up to 8 days, or aged for 72 hours and primed. The force required to puncture 5-mm-long, micropylar seed pieces was measured using an Instron universal testing machine. Less force was required to puncture primed seed pieces at 0, 5, 15, 20, and 25 hours of imbibition, demonstrating that osmotic priming weakens the perisperm envelope tissue that the radicle must penetrate for germination to occur. In an earlier report, germination rate and final germination percentages were higher for osmotically primed seeds both in laboratory tests and field emergence studies conducted immediately after priming. After 9 years in storage, nonprimed seeds germinated to higher percentages in water at 30C and reduced water potential at all temperatures, while primed seeds germinated to higher percentages in water at 20 and 25C and exhibited a higher percentage of seedling emergence at a soil MC of 17%. Priming durations of ≤5 days had no effect on the viability, while longer durations decreased the viability of stored primed and nonprimed seeds. Priming generally decreased the log mean time to germination of stored nonprimed seeds but increased values for stored primed seeds. Controlled deterioration increased the log mean time to germination and decreased the viability of primed seeds faster than nonprimed seeds. Priming following controlled deterioration had no effect on nonprimed seeds and reduced the percent viability of primed seeds by 20%. Osmotic priming has a deleterious effect on the seed storage life of muskmelon seeds.
Adsorption, Mobility, and Filtration of Metolachlor in Container Media
Authors: Grey Timothy L. , Wehtje Glenn R. , Hajek Ben F. , Gilliam Charles H. , Keever Gary J. , Pace Patrick
Published: January 2019

Adsorption, mobility, and filtration ability of organic media toward metolachlor were evaluated in a series of laboratory experiments. Experimental variables included media type, metolachlor concentration, and equilibration time. Adsorption isotherms were determined by applying the log form of the Freundlich equation. Mobility was evaluated using glass columns filled with media, which were then surface spiked with metolachlor and then leached daily for 10 consecutive days. Peat, pine bark, combinations of these two media and a mixture of pine bark and sand adsorbed >90% of the 14C metolachlor. Freundlich sorption coefficients were 10.9, 18.2, 13.4, 14.2, and 11.0 for pine bark, peat, 5 pine bark: 1 peat, 3 pine bark: 1 peat, and 5 pine bark: 1 sand, respectively. In a timed exposure experiment using bark, minimum metolachlor adsorption (57%) was at 90 seconds and maximum adsorption (82%) required at least 1440 minutes. In column leaching studies, data for all media indicate that metolachlor is relatively immobile through these substrates. An initial pulse of metolachlor (<1.0 μg·liter-1) was detected with each medium up to the third wetting event with a subsequent decline (>0.5 μg·liter-1 for each medium) in the metolachlor recovered. Filtration efficiency of commercially formulated metolachlor from water passed through different lengths of pine bark filled filters was 0%, 17%, 20%, 22%, 23%, and 29% for filters 4, 20, 12, 8, 16, and 24 cm in length, respectively. These results support the contention that such filtration would be effective provided the residence time of water within the filter was sufficient for adsorption of the contaminant by the media to occur.
Assessing Cold Hardiness of Red Raspberry Genotypes in the Laboratory and Field
Authors: Zatylny Annette M. , Proctor J.T.A. , Sullivan J.A.
Published: January 2019

Tissue survival assessments of red raspberry (Rubus idaeus L.), including cane dieback, bud death, time of cane leaf drop, and growth cessation, were compared to freezing tests of stem portions and buds. Four named cultivars and six Guelph (designated Gu) selections were assessed in the field at two locations in each of two winters and in concurrent controlled freezing tests at one location for one winter. The time of cane leaf drop and of cessation of cane extension growth in the fall were not correlated with field survival. Cane dieback as a percentage of cane length was a better estimate of winter survival than was bud number. Controlled freezing tests of stem portions and buds, and calculation of T40s and T50s indicate that genotypes differed in their relative hardiness throughout the winter. The different methods of field assessment of cold hardiness were well correlated, but not well correlated with controlled freezing tests (4.2% significant correlations). Exclusion of the genotype, Gu 75, which behaved differently in the field than in freezing tests, increased the number of significant correlations to 16.7%.
Influence of Day and Night Temperatures on Sweet Pepper Seedling Development
Authors: Si Yaping , Heins Royal D.
Published: January 2019

Sweet pepper (Capsicum annuum `Resistant Giant no. 4') seedlings were grown for 6 weeks in 128-cell plug trays under 16 day/night temperature (DT/NT) regimes from 14 to 26 °C. Seedling stem length, internode length, stem diameter, leaf area, internode and leaf count, plant volume, shoot dry weight (DW), seedling index, and leaf unfolding rate (LUR) were primarily functions of average daily temperature (ADT); i.e., DT and NT had similar effects on each growth or development parameter. Compared to ADT, the difference (DIF, where DIF = DT - NT) between DT and NT had a smaller but still statistically significant effect on stem and internode length, leaf area, plant volume, stem diameter, and seedling index. DIF had no effect on internode and leaf count, shoot DW, and LUR. The root: shoot ratio and leaf reflectance were affected by DT and DIF. Positive DIF (DT higher than NT) caused darker-green leaf color than negative DIF. The node at which the first flower initiated was related to NT. The number of nodes to the first flower on pepper plugs grown at 26 C NT was 1.2 fewer than those of plants grown at 14 °C NT.
High Carbon dioxide Delays Postharvest Changes in RuBPCase and Polygalacturonase-related Protein in Cherimoya Peel
Authors: Del Cura Begoña , Escribano María I. , Zamorano Jose P. , Merodio Carmen
Published: January 2019

The peel of `Fino de Jete' cherimoya (Annona cherimola Mill.) stored at 20 °C in air and in an atmosphere with high levels of CO2 was analyzed for changes in protein levels, color, chlorophyll content, and firmness. The accumulation of immunoreactive proteins was studied using Rubisco and polygalacturonase antibodies. During storage in air, cherimoya peel tissues exhibited a decrease in chlorophyll content and an immunodetected drop in the abundance of the large subunit of ribulose 1,5-biphosphate carboxylase (LSR). An immunodetected rise in polygalacturonase (PG)-related protein was quantified. High CO2 levels delayed the softening of cherimoya fruit, retarded the maximum accumulation of PG-related protein, and maintained LSR levels, greenness, and chlorophyll content of peel tissues.
Storage and Viability Testing of Protea Pollen
Authors: van der Walt I. David , Littlejohn Gail M.
Published: January 2019

The influence of storage temperature and humidity on pollen viability was studied in four Protea species. Pollen was stored at a range of temperatures and relative humidities for up to 1 year and tested for ability to germinate in vitro. Pollen of P. repens (L.) L. `Sneyd', P. eximia (Salisb. ex Knight) Fourcade `Fiery Duchess' and P. magnifica Link. clone T 84 07 05 stored at -196 °C and -14 to -18 °C retained a germination percentage as high as that of fresh pollen regardless of humidity. Humidity control became increasingly important at storage temperatures above 0 °C. The study showed that long-term storage of Protea pollen is not feasible at temperatures above 0 °C. The relationship between germinability and fluorochromasia (FCR) was studied during storage of `Sneyd' pollen. The correlations between FCR and germinability were found to be low and nonsignificant. Fifteen-month-old cryopreserved `Sneyd' pollen functioned in fertilization and seed set as effectively as fresh pollen.
Response to Selection for Salt Tolerance during Germination in Tomato Seed Derived from PI 174263
Authors: Foolad M.R.
Published: January 2019

The effectiveness of directional phenotypic selection to improve tomato (Lycopersicon esculentum Mill.) seed germination under salt-stress was investigated. Seed of F2 and F3 progeny of F1 hybrids between a salt-tolerant (PI174263) and a salt-sensitive (UCT5) tomato cultivar were evaluated for germination response at three stress levels of 100 (low), 150 (intermediate), and 200 mm (high) synthetic sea salt (SSS). At each salt-stress level, the most tolerant individuals, as determined by the germination speed, were selected. Selected individuals (F2s or F3s) were grown to maturity and self-pollinated to produce F3 and F4 progeny families. The selected progeny from each experiment were evaluated for germination at four treatment levels of 0 (nonstress), 100, 150, and 200 mm SSS and were compared with unselected populations. The results indicated that selections were equally effective at all three salt-stress levels and in F2 and F3 generations and significantly improved seed germination of progeny under salt-stress and nonstress treatments. Estimates of realized heritability for rapid germination under the various salt-stress levels ranged from 0.67 to 0.76. Analysis of response and correlated response to selection indicated a genetic correspondence of up to 100% between germination at different salt-stress levels. Genotypic family correlations between germination at the low, intermediate, and high salt-stress levels ranged from 0.67 to 0.89, and those between nonstress and salt-stress conditions ranged from 0.25 (between 0 and 200 mm) to 0.71 (between 0 and 100 mm salt). The results indicated that similar or identical genes with additive genetic effects contributed to rapid germination response of tomato seeds at different salt-stress levels. Thus, selection at one stress level resulted in progeny with improved germination at diverse salt-stress levels. The results also indicated that to improve tomato seed germination, selection can be based on individual seed performance and early segregating generations.
DNA Amplification Fingerprinting Identifies Closely Related Chrysanthemum Cultivars
Authors: Scott M.C. , Caetano-Anollés G. , Trigiano R.N.
Published: January 2019

DNA amplification fingerprinting (DAF) was used to study genetic relationships between closely related chrysanthemum cultivars (Dendranthema grandiflora Tzvelev.). Twenty-one cultivars were examined that belonged to the Anne, Blush, Boaldi, Charm, Davis, and Pomona series (families). The genetic variability of cultivars within and between series was evaluated using eleven arbitrary octamer primers. A few polymorphic characters uniquely identified closely related cultivars within each of the series. In contrast, many DNA polymorphisms were observed between members of the different series. Phenetic patterns were established by unweighted pair group cluster analysis using arithmetic means (UPGMA) and principal coordinate analysis (PCO). The average distance between series was 10-fold greater than between cultivars within a series. DNA from all cultivars belonging to a series were also bulked to generate profiles containing unique amplified products for each series. Cluster analysis and PCO of bulked DNA clearly grouped Charm and Pomona together. However, series grouping did not correspond to morphology of inflorescence types. The results demonstrate the utility of the DAF technique in distinguishing clonal materials and its potential use for patent protection, phylogenetic studies, and for identifying useful markers in breeding applications.
Control of Bolting in Autumn-sown Sweet Onions through Undercutting
Authors: Sanders Douglas C. , Cure Jennifer D.
Published: January 2019

The efficacy of undercutting as a technique to control bolting of two short-day onion cultivars was studied in controlled-environment chambers. `Buffalo' and `Granex 33' onions were grown to the third, fifth, and seventh visible leaf stages in a 10-hour photoperiod at 22/18 °C (day/night) and then exposed to 30, 40, 50, 60, or 70 days of vernalizing temperatures (10/10 °C). Half of the plants were undercut at the initiation of the vernalizing treatment. After vernalizing treatments, plants were returned to 14-hour photoperiods at 22/18 °C. `Buffalo', which is resistant to bolting, did not flower significantly under any of these conditions. The flowering response of `Granex 33' increased with leaf number at vernalization and as the duration of vernalization increased. Undercutting `Granex 33' increased the days of vernalization required for flowering and reduced the proportion of flowering relative to controls. Overall dry-matter accumulation was unaffected by leaf number at vernalization or the duration of vernalization but was reduced ≈30% by undercutting. In both cultivars, fresh mass per bulb decreased with increasing leaf stage of vernalization and number of vernalizing days. Undercutting also decreased fresh mass per bulb, but through its effect on bolting, undercutting increased marketable yield for plants vernalized and undercut at the fifth and seventh leaf stages.
Physiological and Chemical Changes during Ripening of Costa Rican Bananas Harvested in Different Seasons
Authors: Marin Douglas H. , Blankenship Sylvia M. , Sutton Turner B. , Swallow William H.
Published: January 2019

Mature green `Grande Naine' bananas (Musa AAA) were harvested 13 weeks after flowering in June and Sept. 1993 and Feb. and Mar. 1994 and were sent air freight to Raleigh, N.C. Fruit were held under 1) storage (36 days at 14 C and 80% to 90% relative humidity) or 2) ripening (8 days storage, followed by ethylene treatment on day 8 and subsequent storage at 17 °C and 80% to 90% relative humidity). Despite of similar grade and age, length of the preclimacteric phase (green life) was different between fruit harvested at different times of the year. Fruit harvested in February and March had a longer green life than those harvested in June and September. Rate of respiration best described changes that occurred during the postharvest life of bananas; however, variables such as pulp pH and soluble solids could be commercially useful measures. Once gassed with ethylene, ripening rates were similar between all four lots of fruit, indicating that seasonal variation probably doesn't contribute much to variability seen during ripening. Hand position in the bunch did not have a large influence on variability during ripening or storage.
Color, Ethylene Production, Respiration, and Compositional Changes in Broccoli Dipped in Hot Water
Authors: Tian M.S. , Islam Talebul , Stevenson D.G. , Irving D.E.
Published: January 2019

Color, ethylene production and respiration of broccoli (Brassica oleracea L. var. italica) dipped in hot water (45 °C, 10 minutes; 47 °C, 7.5 minutes; and 20 °C, 10 minutes as control) were measured. Hot-water treatment (HWT) delayed yellowing. Compared to the control, ethylene production and respiration in broccoli dipped at 45 °C decreased but recovered, and rates of both were enhanced after 24 and 48 hours, respectively, at 20 °C in darkness. There was no recovery of ethylene production or respiration in broccoli dipped at 47 °C. Following HWT of 47 °C for 7.5 minutes, respiration, starch, sucrose, and soluble protein content of florets and stems decreased dramatically during the first 10 to 24 hours after harvest. At the same time, fructose contents in florets and stems increased. Glucose increased in the florets but decreased within 24 hours in stems. Thereafter, glucose and fructose in florets and stems decreased. Sucrose content in florets and stems increased dramatically within a short period of treatment (<10 hours) and then declined. Protein in HWT florets and stems decreased during the first 24 hours and then increased until 72 hours. Ammonia content was lower in HWT broccoli during the first 24 hours and then increased above the level in the controls.
Effect of Elevated Carbon Dioxide on the Growth and Physiological Responses of Pineapple, A Species with Crassulacean Acid Metabolism
Authors: Zhu Jun , Bartholomew Duane P. , Goldstein Guillermo
Published: January 2019

Despite the potential impact of rising global CO2 levels, only a limited number of studies have been conducted on the effects of ambient and elevated CO2 on plants having Crassulacean acid metabolism (CAM). To our knowledge, there are no studies for pineapple [Ananas comosus (L.) Merr.], the most commercially important CAM plant. Pineapple plants were grown at CO2 levels of ≈330 (ambient) and ≈730 (elevated) μmol·mol-1 in open-top chambers for 4 months. The mean air temperature in the chambers was ≈39 °C day/24 °C night. Average plant dry mass at harvest was 180 g per plant at elevated CO2 and 146 g per plant at ambient CO2. More biomass was partitioned to stem and root but less to leaf for plants grown at elevated CO2; leaf thickness was 11% greater at elevated than at ambient CO2. The diurnal difference in leaf titratable acidity (H+) at elevated CO2 reached 347 mmol·m-2, which was up to 42% greater than levels in plants grown in ambient CO2. Carbon isotopic discrimination (Δ) of plants was 3.75% at ambient CO2 and 3.17% at elevated CO2, indicating that CO2 uptake via the CAM pathway was enhanced more by elevated CO2 than uptake via the C3 pathway. The nonphotochemical quenching coefficient (qN) of leaves was ≈45% lower in the early morning for plants grown at elevated than at ambient CO2, while afternoon values were comparable. The qN data suggested that the fixation of external CO2 was enhanced by elevated CO2 in the morning but not in the afternoon when leaf temperature was ≥40 °C. We found no effect of CO2 levels on leaf N or chlorophyll content. Pineapple dry matter gain was enhanced by elevated CO2, mainly due to increased CO2 dark fixation in environments with day temperatures high enough to suppress C3 photosynthesis.
Changes in Carbohydrates and Carbohydrate Metabolizing Enzymes during the Development, Maturation, and Ripening of Buttercup Squash (Cucurbita maxima D. `Delica')
Authors: Irving Donald E. , Hurst Paul L. , Ragg Jonathan S.
Published: January 2019

During this study, we divided the developmental growth pattern of buttercup squash into three phases: 1) early growth, from flowering up to 30 days after flowering; 2) maturation, from 30 days until 60 days after flowering (or harvest); and 3) ripening, from 60 days (or harvest) until ≈100 days after flowering. Harvest occurred at 48 days after flowering. Fruit growth (expansion), starch, and dry matter accumulation were largely completed during early growth, and there was a progressive decline in the respiration rate. Extractable activities of acid and alkaline invertases, sucrose synthase, alkaline α-galactosidase, and sucrose phosphate synthase (assayed with saturating substrates) were high initially but declined markedly during this phase. Glucose, fructose, and low concentrations of raffinose saccharides were present, but no sucrose was detected. During maturation, starch and dry matter remained nearly constant and sucrose began to accumulate. During ripening, starch was degraded, sucrose synthase activity was significant but relatively constant, sucrose phosphate synthase activity increased, and sucrose continued to accumulate.
Molecular-marker-based Genetic Analysis of Tepary Bean-derived Common Bacterial Blight Resistance in Different Developmental Stages of Common Bean
Authors: Jung Geunhwa , Skroch Paul W. , Coyne Dermot P. , Nienhuis James , Arnaud-Santana E. , Ariyarathne H.M. , Kaeppler Shawn M. , Bassett Mark J.
Published: January 2019

Randomly amplified polymorphic DNA (RAPD) molecular markers were used to construct a partial genetic linkage map in a recombinant inbred population derived from the common bean (Phaseolus vulgaris L.) cross PC-50 × XAN-159 for studying the genetics of bacterial disease resistance in common bean. The linkage map spanned 426 cM and included 168 RAPD markers and 2 classical markers with 11 unassigned markers. The seventy recombinant inbred lines were evaluated for resistance to two strains of common bacterial blight [Xanthomonas campestris pv. phaseoli (Smith) Dye] (Xcp). Common bacterial blight (CBB) resistance was evaluated for Xcp strain EK-11 in later-developed trifoliolate leaves and for Xcp strains, DR-7 and EK-11, in first trifoliolate leaves, seeds, and pods. One to four quantitative trait loci (QTLs) accounted for 18% to 53% of the phenotypic variation for traits. Most significant effects for CBB resistance were associated with one chromosomal region on linkage group 5 and with two regions on linkage group 1, of the partial linkage map. The chromosomal region (a 13-cM interval) in linkage group 5 was significantly associated with resistance to Xcp strains DR-7 and EK-11 in leaves, pods, and seeds. The regions in linkage group 1 were also significantly associated with resistance to both Xcp strains in more than one plant organ. In addition, a seedcoat pattern gene (C) and a flower color gene (vlae) were mapped in linkage groups 1 and 5, respectively, of the partial linkage map. The V locus was found to be linked to a QTL with a major effect on CBB resistance.
Effect of Surfactants on Pressure Infiltration of Calcium Chloride Solutions into `Golden Delicious' Apples
Authors: Saftner Robert A. , Buta J. George , Conway William S. , Sams Carl E.
Published: January 2019

The effects of 36 organosilicone and conventional carbon-based surfactants on postharvest infiltration of radiolabeled and unlabeled Ca solutions into `Golden Delicious' apples (Malus domestica Borkh) were examined to devise a more efficient pressure infiltration technique to increase fruit Ca concentration. Radiolabeled Ca infiltration and the proportional increase in fruit Ca estimated by fruit weight gain from Ca solutions of known concentration were significantly enhanced by a range of surfactants having different chemical structures. Tween 60 and 80; Triton X-45, X-100, X-114, X-305, and X-405; and Silwet L-77 and L-7604 enhanced Ca infiltration. The two organosilicone surfactants, Silwet L-77 and Silwet L-7604, known for their greater capacity to lower the surface tension of solutions than conventional carbon-based surfactants, were the most effective at augmenting Ca infiltration. Applications of surfactants to fruit were as or more effective when used as a pretreatment rather than mixing the surfactant with the Ca solutions. The pressure necessary to increase Ca to levels considered sufficient to maintain fruit firmness and resist decay during storage could be lowered in fruit treated with organosilicone surfactants. Sequential postharvest surfactant and Ca treatments may be a practical means of increasing the Ca concentration in apples.
Irrigation and Crop Load Interactions in Relation to Apple Yield and Fruit Size Distribution
Authors: Naor A. , Klein I. , Doron I. , Gal Y. , Ben-David Z. , Bravdo B.
Published: January 2019

The interaction between irrigation and crop load with respect to fruit size distribution was investigated in a `Golden Delicious' apple (Malus domestica Borkh) orchard located in a semi-arid zone. Irrigation levels during the main fruit expansion phase ranged from 0.42 to 1.06 of the Class A pan evaporation coefficient. Crop load was adjusted to 100 to 450 fruit/tree in the 1250 trees/ha orchard by hand thinning. Total yield was not affected by irrigation level up to a crop load of 200 fruit/tree. Yield of all grades >65 mm was affected by irrigation level for higher crop densities. The yield of fruit of diameter <75 mm was not affected by increasing the Class A pan evaporation coefficient above 0.75. Our data indicate that availability of assimilates may limit the size of fruit with potential to grow larger than 70 mm in diameter at all crop loads higher than 200 fruit/tree. This limitation increases with decreasing irrigation level. The volumetric relative growth rate (VRGR) increased with irrigation level and with decreasing crop load. VRGR was more affected by crop load than by irrigation level in the ranges studied.
Foliar Heat Tolerance of Three Holly Species (Ilex spp.): Responses of Chlorophyll Fluorescence and Leaf Gas Exchange to Supraoptimal Leaf Temperatures
Authors: Ranney Thomas G. , Ruter John M.
Published: January 2019

Temperature sensitivity of CO2 assimilation (ACO2), dark respiration, and chlorophyll fluorescence was evaluated among three taxa of hollies including I. aquifolium L., I. cornuta Lindl. & Paxt., and I. rugosa Friedr. Schmidt. Variations in foliar heat tolerance among these species were manifested in temperature responses for ACO2. Temperature optima of ACO2 for I. rugosa, I. cornuta, and I. aquifolium were 22.0, 26.3, and 27.9 °C, respectively (LSD0.05 = 2.9). Temperature responses of respiration were similar among taxa and did not appear to be contributing factors to variations in ACO2. At 40 °C, potential photosynthetic capacity, measured under saturating CO2, was 4.1, 9.4, and 14.8 μmol·m-2·s-1 for I. rugosa, I. aquifolium, and I. cornuta, respectively (LSD0.05 = 5.1). Variations in the relative dark-acclimated fluorescence temperature curves were used to assess thresholds for irreversible heat injury. The critical fluorescence temperature threshold (TC) was similar (48.0 °C) for all taxa. The fluorescence temperature peaks (TP) were 52.0, 52.8, and 53.5 °C for I. rugosa, I. cornuta, and I. aquifolium, respectively (LSD0.05 = 0.9). Based on these results, I. rugosa was the most heat-sensitive species, followed by I. aquifolium and I. cornuta. Ilex cornuta also had substantially greater potential photosynthetic capacity than the other species at 40 °C, indicating superior metabolic tolerance to high temperatures.
Genetic Analysis of Yield Components in Cucumber at Low Plant Density
Authors: Serquen Felix C. , Bacher Jeff , Staub Jack E.
Published: January 2019

Plant architecture can be manipulated in cucumber (Cucumis sativus L.) to provide an array of phenotypes. Determinate, multiple-lateral plants are unique because they afford an opportunity to increase fruit yield per plant. Estimates of genetic variances, numbers of genetic factors, and genotypic and phenotypic correlations between traits were made in a population, segregating for sex expression, leaf size, and plant habit at low plant density (≈19,000 plants/ha). Replicated evaluation of 100 F3 families derived from an initial mating between a gynoecious, determinate, moderately branched line (G421) and a monoecious, indeterminate, multiple lateral branching line (`H-19') indicated that mainstem length and multiple lateral branching exhibit mostly additive genetic variance. For sex expression, additive and dominant genetic variances were important. The minimum number of genetic factors controlling sex expression, number of lateral branches, and mainstem length were estimated at five, four, and eight, respectively. Phenotypic and genotypic correlations between traits indicated that relative leaf size may influence fruit mass while having only limited influence on the number of fruit produced per plant. The amount and type of genetic variation suggests that the development of an array of determinate, multiple-lateral branching plant types with varying sex expression and plant stature is possible.
Impacts of Copper Leaching From Copper Hydroxide-treated Containers on Water Recycling, Nursery Runoff, and Growth of Baldcypress and Corn
Authors: Arnold Michael A. , Wilkerson Don C. , Lesikar Bruce J. , Welsh Douglas F.
Published: January 2019

Studies were conducted using Zea mays L. and Taxodium distichum L. seedlings as model systems to study Cu leaching from Cu(OH)2-treated containers. Initial experiments developed Cu toxicity curves (as CuSO4) in an inorganic (sand) or organic (bark-sand) medium with single (acute) or multiple (chronic) applications. A second pair of experiments investigated short-term (35 days) Cu accumulation and plant responses to irrigation with water (125 mL/plant per day) recycled through a fixed reservoir volume (9.5 L) from 0.7-L Cu(OH)2-treated containers filled with an inorganic or organic medium. Finally, plant responses and Cu leaching were monitored during growth in 2.3-L Cu(OH)2-treated containers filled with two organic media fertigated with high (8.0) or low (6.5) pH solutions. Different Cu(OH)2 concentrations and application methods were tested. Leachate data from the latter studies were used to calculate potential Cu concentrations in nursery runoff using various water application methods and pot spacings. Expression of Cu toxicity symptoms depended on exposure, concentration, and medium for each species. Plants subjected to chronic exposure and grown in an inorganic medium developed toxicity symptoms at lower doses than plants subjected to acute exposure and grown in an organic medium. Several measures of plant growth were greater for both species when grown in 0.7-L Cu(OH)2-treated containers, but not in 2.3-L containers. Plants in Cu(OH)2-treated containers seldom exhibited Cu toxicity symptoms in shoot tissues, even with an inorganic medium. Soluble Cu content of the recycled solution from Spin Out-treated containers increased slightly (<1.2 mg·L-1) during the 35-day experiment. Longer-term studies with nonrecycled leachate from 2.3-L containers indicated that Cu leaching increased after 60 to 90 days. Copper leaching was greater with the combination of applied solution of pH 6.5 and bark-sand-peat medium than with the combination of applied solution of pH 8.0 and bark-sand medium, and increased with greater concentrations of Cu(OH)2 in container wall treatments or when containers were filled before latex carrier was dried. Calculations of potential nursery runoff indicated that the levels of soluble Cu in effluent for most concentrations and spacings projected were below EPA action levels for potable water (1.3 mg·L-1) when overhead irrigation was used.
Nectar Production of Cranberries: Genotypic Differences and Insensitivity to Soil Fertility
Authors: Cane James H. , Schiffhauer Daniel
Published: January 2019

Cranberry flowers (Vaccinium macrocarpon Ait.) require bee visitation for pollination. Bees visit cranberry flowers for nectar and sometimes pollen, but honey bees (Apis mellifera L.) in particular often work alternative co-flowering species for nectar, presumably because cranberry offers inferior nectar rewards. In a common garden setting, replicated plots of the cultivar Stevens were found to secrete significantly more nectar sugar (25% to 35% more) per flower than either `Ben Lear' or `Early Black', two other common commercial cultivars. The nectar secretion rate of `Stevens' was unaffected by a 4-fold range of fertilizer application rates over the preceding 2 years. These results are compared to studies of other crops involving varietal differences and programs of selective breeding for nectar secretion.
Selenate Concentration Affects Selenium and Sulfur Uptake and Accumulation by `Granex 33' Onions
Authors: Kopsell Dean A. , Randle William M.
Published: January 2019

Selenium and sulfur have similar chemical structures. This allows Se to be absorbed and incorporated in the same assimilation pathways as S. Onions (Allium cepa L.) are a crop with unique S metabolism, responsible for growth and flavor intensity. Because of the antagonistic behavior of the two ions, the effects of Se on S and Se nutrient depletion and tissue accumulation were investigated. `Granex 33' onions were grown in nutrient solutions with one concentration of S and increasing Se concentrations. Selenium was applied as sodium selenate (Na2SeO4) at concentrations of 0, 0.5, 1.0, 1.5, and 2.0 mg·L-1. Selenium depletion from the nutrient solution increased linearly with increasing Na2SeO4 treatment concentrations. Sulfur depletion increased and then decreased with increasing Na2SeO4 treatment concentrations. Selenium and S accumulation were highest in leaf tissues, less in root tissues, and lowest in bulb tissues at plant maturity. Selenium accumulation increased linearly with increasing Na2SeO4 for all tissues analyzed. Sulfur accumulation in leaf and bulb tissues was quadratic in response to increasing SeO4-2, while S in root tissues decreased linearly with increasing Na2SeO4. Low concentrations of Na2SeO4 in our study enhanced S uptake and accumulation. Previously, Se was thought to competitively inhibit S uptake and metabolism.
Effect of Mechanical and Moisture-stress Conditioning on Growth and Cuticle Composition of Broccoli Transplants
Authors: Latimer Joyce G. , Severson Ray F.
Published: January 2019

Epicuticular waxes were analyzed to explain the visible differences in the waxy bloom of conditioned broccoli (Brassica oleracea L. Group Italica `Green Duke') transplants. Seedlings (22 days old) were subjected to brushing (40 cycles per minute, 1 minute twice daily), wind (7 m·s-1 for 5 minutes twice daily), or moisture-stress conditioning (MSC; visible wilt for 2 to 4 hours daily) for 16 (1987) or 21 (1988) days during transplant production in the greenhouse. The epicuticular waxes of the uppermost fully expanded leaves were removed by dipping detached leaves into methylene chloride. The extract was derivatized with trimethylsilyl reagents and subjected to capillary gas chromatography. The primary epicuticular wax components were the nonpolar C29 compounds nonacosane, nonacosan-15-ol, and nonacosan-15-one, which were identified by mass spectrometry. In a Summer 1987 experiment, cuticle samples taken over time of treatment indicated acclimation to the conditioning treatments relative to untreated plants. After 9 days of treatment, the amount of total epicuticular waxes present on the leaves was reduced 38%, 31%, or 11% by wind, brushing, or MSC, respectively. However, after 15 days of treatment, the amount of cuticle present was reduced 15% by brushing but only 6% by wind and was 17% greater in MSC-treated plants. Two weeks after transplanting to the field there were no differences in the amount or composition of the epicuticular waxes. In Fall 1988, all treatments reduced plant growth, but only MSC tended to increase the amount of C29 epicuticular components during greenhouse production. Differences in the amounts of epicuticular waxes were no longer significant after 8 days in the field.
Increased Levels of Calcium in the Nutrient Solution Improves the Postharvest Life of Potted Roses
Authors: Starkey Kirsten Rasmussen , Pedersen Asger Roer
Published: January 2019

Experiments were performed on miniature potted roses (Rosa) to investigate whether increasing the Ca concentration in the nutrient solution would increase the Ca concentration in the rose plant, resulting in better postharvest quality. The plants were watered during the whole production period with six different nutrient solutions with Ca at 1.1 to 4.4 mm and varying meq ratios between Ca and the cations. During the postharvest period, plant characteristics were recorded at days 0, 11, 14, 18, and 25. Increasing Ca in the nutrient solution significantly increased the Ca concentration of the plants. However, the NH4 level (2% to 5% vs. 22% to 25%) also influenced the Ca concentration of the plants. Leaves had the highest Ca concentration, which was more than twice the level in flowers and buds, stems and roots. There were no differences in dry matter content between treatments in roots or tops at marketing stage. At the start of the postharvest treatment (day 0), plants from the highest Ca treatment had significantly fewer flowers than those in all of the other treatments due to delayed development. The number of good flowers increased from days 0 to 14 irrespective of treatment, while a further increase to day 18 was observed in plants from the three highest Ca treatments (low NH4) due to a negative effect on flower longevity of low Ca and high NH4 in the three low-Ca treatments. By day 25, the number of good flowers had decreased markedly in all treatments, but plants from the second-highest Ca treatment had significantly more good flowers than plants from the other treatments. Flower wilting was due to infection by grey mold (Botrytis cinerea) and a physiological condition that caused wilting that began at the petal edges with a dark discoloration. Infection with grey mold was negatively correlated with Ca concentration in the flowers. The physiological wilting was seen earlier in plants from the treatments with high NH4 and is probably not related to Ca concentration in the flowers.
Pollen Viability in Lychee
Authors: Stern Raphael A. , Gazit Shmuel
Published: January 2019

The lychee (Litchi chinensis Sonn.) has two types of pollen-releasing flowers—M1 and M2. We compared the morphology and viability of these two pollen types, mainly for the two commercial cultivars in Israel: `Mauritius' and `Floridian'. Observation by scanning electron microscope did not reveal any consistent morphological differences between the two pollen types. However, M2 pollen was found to have a consistent and significant advantage over M1 pollen in in vitro germination tests. M2 pollen from `Mauritius', `Floridian', `No Mai Chee', `Wai Chee', and `Early Large Red' had a much higher germination rate at 15, 20, 25, 30, and 35 °C than M1 pollen from those same cultivars. The optimal incubation temperature for in vitro pollen germination was 30 °C for M2 pollen of all five cultivars studied; adequate germination rates were also found at 35 and 25 °C. The optimal temperature for M1 pollen germination was also 30 °C for `Mauritius' and `No Mai Chee', but was not well defined for the other three cultivars. No pronounced advantage of M2 pollen-tube growth could be discerned 48 h after hand pollination. However, final fruit set was consistently and significantly higher after hand pollination with M2 pollen, relative to M1 pollen. Hot (32/27 °C) and warm (27/22 °C) regimes during flower development had a pronounced detrimental effect on pollen viability compared to a cool (22/17 °C) regime. `Floridian' was much more susceptible than `Mauritius' in this respect.