bluuebunny/crossref_metadata_2025 huggingface dataset:
Stable Transformation of Gladiolus Using Suspension Cells and Callus
Authors: Kamo Kathryn , Blowers Alan , Smith Franzine , Van Eck Joyce , Lawson Roger
Published: January 2019

More than 100 transgenic Gladiolus plants were recovered after particle bombardment of regenerable suspension cells and callus. For transformation, Gladiolus callus and suspension cells were co-bombarded with phosphinothricin acetyltransferase-(PAT) and ß- glucuronidase (GUS) -expressing plasmids. Stably transformed calli were selected on medium containing either phosphinothricin (PPT) or bialaphos followed by transfer to a regeneration medium to recover transgenic plants. Stable transformation was confirmed by detection of the PAT gene by DNA gel blot analysis and by enzymatic assays to measure GUS activity. In general, particle bombardment of regenerable suspension cells rather than callus resulted in the largest number of transformants. The rate of co-expression for GUS in PPT-resistant plants was high (≈ 70%). Promoters that are typically more efficient in dicotyledonous plants were very active in Gladiolus, a monocotyledonous bulb plant. Establishment of an efficient transformation protocol for Gladiolus will now allow the introduction of transgenes to confer resistance to the viral and fungal pathogens that decrease Gladiolus production.
Masting in Pecan
Authors: Chung Chung Soo , Harris Marvin K. , Storey J. Benton
Published: January 2019

Annual variation in fruiting by pecan [Carya illinoensis (Wangenh.) K. Koch] obtained from anecdotal records and state, district, county, and orchard data from Texas indicate exceptionally high synchronous fluctuations typically occurred every 34 years with a range of 2-7 years over the 66-year data base examined. Synchrony in fruit production was inversely related to the spatial distribution of pecans reflected in coefficients of variation ranging from about 60 at the state level to about 120 for two 10-ha orchards. These characteristics show that pecan exhibits roasting and that the species warrants further examination vis a vis interactions with nut feeders.
Reclaimed Wastewater Irrigation and Fertilization of Mature `Redblush' Grapefruit Trees on Spodosols in Florida
Authors: Maurer Michael A. , Davies Frederick S. , Graetz Donald A.
Published: January 2019

An experiment was designed to determine the effects of canal water and reclaimed wastewater on growth, yield, and fruit quality of mature (25-year-old) `Redblush' grapefruit (Citrus paradisi Macf.) trees on sour orange (C. aurantium L.) rootstock. The study was conducted from 1 Oct. 1990 to 18 Apr. 1994 at a site adjacent to the Indian River County municipal wastewater treatment facility located near Vero Beach, Fla. Treatments included canal water applied based on one-third or two-thirds soil water depletion and reclaimed wastewater applied using microsprinklers at 23.1 mm/week (low), 30.7 mm/week (moderate) and 38.6 mm/week (high). Trees receiving low and moderate levels of reclaimed wastewater had the largest canopies and trunk diameters and highest yields, even though the amount of fertilizer applied was less than that of canal water plots. Leaf nutrient levels were generally within acceptable ranges for N, P, K, Ca, Mg, and Na except in 1991 when levels were deficient due to excessive rainfall and leaching. Leaf B levels were similar for all reclaimed wastewater treatments but were lower for the canal water treatment in 1992 and 1993. Fruit growth rate, fruit and juice weight, total soluble solids (TSS), titratable acidity (TA), and TSS: TA ratio were similar for all treatments in 2 of 3 years. Peel thickness was similar for all treatments. Heavy metal concentration in the reclaimed wastewater was at low or nondetectable levels. Similarly, enteric viruses in the effluent were always <0.003 plaque forming units/liter. Reclaimed wastewater irrigation significantly increased weed growth compared to the canal water treatment.
Seasonal and Cropping Effects on Total and Fertilizer Nitrogen Use in June-bearing and Day-neutral Strawberries
Authors: Archbold Douglas D. , MacKown Charles T.
Published: January 2019

Total N and fertilizer N (FN) recovery and use by June-bearing `Redchief' strawberry (Fragaria ×ananassa Duch.) and day-neutral `Tribute' grown in matted-row beds were studied over l-year periods. Fertilizer N was field-applied as NH NO at planting in June or September, and all plants were harvested from bed sections in late autumn (November) and at the completion of the spring harvest (June). Distribution patterns of vegetative biomass were similar in both cultivars, with leaf tissue comprising the bulk of the vegetative dry weight per plant at both sampling dates. The fall and spring fruit crops each contributed >40% of the total biomass per plant. Total N accumulation from soil N and FN increased as total biomass increased. Due in part to the additional biomass of the fall fruit crop, `Tribute' recovered 38% more total N per unit bed area than `Redchief'. Over 30% of the fall N total in `Tribute' and the spring N total in both cultivars was partitioned to the fruit. In both cultivars, greater recovery of FN applied in September that at planting time was observed by the postharvest sampling date. However, `Tribute' recovered only 14.2% of the FN applied in September, much less than the amount recovered by `Redchief' during the same interval, implying a diminished ability to absorb FN during fruiting. In all vegetative tissues, soluble reduced N (SRN) was consistently less than insoluble reduced N (IRN) in November and June. Consistent seasonal trends in SRN and IRN values were not evident in any tissue except roots, where SRN content declined from November to June. Allocation of FN to the SRN and IRN pools was related to FN application date, cropping pattern, and total biomass of the component tissue. In both cultivars, the FN content was greater in the IRN than the SRN pool and leaf IRN was the single largest vegetative sink for FN. Fruit N concentration was constant for most of the fall `Tribute' harvest period and declined in both cultivars during spring harvest. The spring `Tribute' fruit crop received more FN from the September than the planting application, while the fall crop exhibited the opposite pattern, suggesting the fruit crop receives more storage than newly absorbed FN. The accumulation of FN in the root SRN pool in November and its depletion through the spring harvest reveals that root SRN plays a significant role in the temporary seasonal storage and internal cycling of N remobilized during spring growth.
Heat Tolerance of Selected Species and Populations of Rhododendron
Authors: Ranney Thomas G. , Blazich Frank A. , Warren Stuart L.
Published: January 2019

Temperature sensitivity of net photosynthesis (PN) was evaluated among four taxa of rhododendron including Rhododendron hyperythrum Hayata, R. russatum Balf. & Forr., and plants from two populations (northern and southern provenances) of R. catawbiense Michx. Measurements were conducted on leaves at temperatures rauging from 15 to 40C. Temperature optima for PN ranged from a low of 20C for R. russatum to a high of 25C for R. hyperythrum. At 40C, PN rates for R. hyperythrum, R. catawbiense (northern provenance), R. catawbiense (southern provenance), and R. russatum were 7.8,5.7,3.5, and 0.2 μmol·m-2·s-1, respectively (LSD0.05 = 1.7). Rhododendron catawbiense from the southern provenance did not appear to have greater heat tolerance than plants from the northern provenance. Differences in dark respiration among taxa were related primarily to differences in tissue weight per unit leaf surface area. Temperature coefficients (Q5) for respiration did not vary in temperature response among taxa. Differences in heat tolerance appeared to result from a combination of stomatal and nonstomatal limitations on PN at high temperatures.
Gas Exchange of Citrus Seedlings at Different Temperatures, Vapor-pressure Deficits, and Soil Water Contents
Authors: Brakke M. , Allen L.H.
Published: January 2019

Midday reductions of stomatal conductance and carbon dioxide assimilation rates (Aco2) in Citrus are typically attributed to large leaf-to-air vapor-pressure differences or high atmospheric vapor-pressure deficits (VPD). This study investigated air temperature (Ta) and available soil water (ASW) level as corollary factors of atmospheric VPD that influence midday reduction of net gas exchange in citrus leaves. The influence of elevated atmospheric CO2 under conditions that inhibit net canopy Aco2 was also investigated. Net canopy Aco2 and evapotranspiration rates of Carrizo citrange [Poncirus trifoliata Raf × Citrus sinensis (L.) Osbeck] and Swingle citrumelo (P. trifoliata Raf × C. paradisii Macf.) seedlings grown in outdoor controlled-environment growth chambers were measured under two levels of Ta with concomitant changes in VPD and two levels of atmospheric CO2 concentration, which were changed in steps over time. Cyclical depletion of ASW was allowed to occur at each set of Ta/VPD and CO2 combinations. Highest net canopy Ace, rates at ambient CO2 concentration (330 μmol·mol-1) were obtained at the low Ta/VPD level (29C/2.4 kPa) and ASW >50%. Diurnal canopy CO2 uptake rates decreased at the high Ta/VPD level (37C/3.6 kPa), and midday depression of canopy Aco2 was observed at ASW levels <50%. Net canopy Aco2 decreased at higher levels of ASW under the high Ta/VPD treatment than at the low Ta/VPD treatment. At the elevated CO2 concentration (840 μmol·mol-1) net canopy CO2 uptake rates were double those that occurred at ambient CO2 levels and they did not exhibit midday reduction. Our data indicate that, when soil water is not readily available, citrus seedlings are more sensitive to high levels of Ta and VPD which results in reduction of CO2 uptake. The inhibitory effects of elevated VPD and reduced ASW on citrus net Aco2 were lessened at the elevated atmospheric CO2 level.
In Vitro [14C]Citrate Uptake by Tonoplast Vesicles of Acidless Citrus Juice Cells
Authors: Canel Camilo , Bailey-Serres Julia N. , Roose Mikeal L.
Published: January 2019

The acidless phenotype of the pummelo 2240 [Citrus maxima [Burro.] Merrill] is caused by a mutation affecting a key element of the citric acid accumulation pathway. To test the functionality of the tonoplast citrate transport mechanism, we obtained a tonoplast-enriched membrane fraction from juice tissues of acidless fruit by centrifugation through a discontinuous Ficoll gradient. The isolated tonoplast vesicles incorporated radioactively labeled citrate at a higher rate than vesicles from similarly fractionated high-acid fruit juice. Uptake of [14C]citrate occurred against a concentration gradient was stimulated by nitrate-sensitive ATP hydrolysis, but not by hydrolysis of PPi, and was not affected by the ionophore nigericin. Uptake was not inhibited by malate and only slightly by isocitrate. We did not find evidence of a defective citrate transport mechanism at the tonoplast of juice cells of acidless fruit. We propose that citric acid accumulation in the fruit of citrus is mediated by a carrier that uses energy produced during hydrolysis of ATP to transport citrate into the vacuole actively and specifically.
Random Amplified Polymorphic DNA Analysis of Olive (Olea europaea L.) Cultivars
Authors: Fabbri A. , Hormaza J.I. , Polito V.S.
Published: January 2019

Seventeen olive (Olea europaea L.) cultivars, including oil and table olive cultivars originating from throughout the Mediterranean area, were screened using random amplified polymorphic DNA (RAPD) markers. The results indicate that a high degree of polymorphism is evident in the olive germplasm reexamined. Forty random decamer primers were screened; seventeen of these produced 47 reproducible amplification fragments useful as polymorphic markers. Each of the 17 cultivars can be discriminated with a few primers. Results were analyzed for similarity among the cultivars and a cluster analysis was performed. These analyses revealed two main groups: one comprising primarily small-fruited cultivars grown mainly for oil production, and the other characterized by having large fruit. There was no apparent clustering of olive cultivars according to their geographic origins.
Identities and Relationships among Chinese Vegetable Brassicas as Determined by Random Amplified Polymorphic DNA Markers
Authors: Ren Jianping , McFerson James R. , Li Rugang , Kresovich Stephen , Lamboy Warren F.
Published: January 2019

Fifty-two germplasm accessions of Chinese vegetable brassicas were analyzed using 112 random amplified polymorphic DNA (RAPD) markers. The array of material examined spanned a wide range of morphological, geographic, and genetic diversity, and included 30 accessions of Brassica rapa L. (Chinese cabbage, pakchoi, turnip, and broccoletto), 18 accessions of B. juncea (L.) Czern. (leaf, stem, and root mustards), and four accessions of B. oleracea L. ssp. alboglabra (Chinese kale). The RAPD markers unambiguously identified all 52 accessions. Nei-Li similarities were computed and used in unweighed pair group method using arithmetic means (UPGMA) cluster analyses. Accessions and subspecies were clustered into groups corresponding to the three species, but some accessions of some subspecies were most closely related to accessions belonging to other subspecies. Values for Nei-Li similarities suggest that Chinese cabbage is more likely to have been produced by hybridization of turnip and pakchoi than as a selection from either turnip or pakchoi alone. RAPD markers are a fast, efficient method for diversity assessment in Chinese vegetable brassicas that complements techniques currently in use in genetic resources collections.
Effect of Ethephon Spray Treatments on Mechanical Harvesting and Oil Composition of `Arbequina' Olives
Authors: Touss J. , Lloveras J. , Romero A.
Published: January 2019

Ethephon was applied at 0, 625, 1250, 1875, and 2500 m·gliter-1 in 2 consecutive years to `Arbequina' olive trees to determine its effect on fruit removal with mechanical harvesting and on fruit oil composition. Ethephon increased the mechanical harvesting efficiency by 20%. Ethephon at 1250 and 1875 mg·liter-1 were the optimum treatments, resulting in 63% and 66% of the olives being mechanically harvested, respectively, with a preharvest olive drop of 10% and 11%. Leaf drop (4.6 and 4.8 kg/tree fresh weight, respectively) at these concentrations did not reduce flowering the following year. Oil acidity, peroxide value, and fatty acid composition were affected little by ethephon and the values observed were within the range of normal annual variation. These results suggest that ethephon did not modify oil quality and that its use on traditionally pruned `Arbequina' trees is not economically justifiable. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
Relationship of Reproductive and Vegetative Characteristics of Pecan to Previous-season Fruit Development and Postripening Foliation Period
Authors: Wood B.W.
Published: January 2019

Alternately bearing `Cheyenne' pecan [Carya illinoensis (Wangenh.) K. Koch] trees were studied to assess the temporal aspects of previous season fruit development on several reproductive and vegetative traits of horticultural importance. Action spectra were generated and used to identify the relative sensitivities of these traits to the temporal aspects of fruiting. Based on date of maximum rate of change in sigmoidal models fitted to these action spectra, the relative sensitivity of certain important growth and developmental parameters to fruit removal time was number of distillate flowers per terminal shoot > number of distillate flowers per flower cluster on lateral shoots> length of terminal shoots > percentage of lateral shoots with fruit= catkins per terminal shoot at top of the tree> percentage of terminal shoots with fruit > catkins per standard terminal shoot> shoots produced per l-year-old branch> percentage of l-year-old shoot death. Maximum rates of change for these reproductive and vegetative parameters were typically during the dough stage of ovule development; however, substantial change also occurred for several parameters over a much wider developmental window. No evidence was found for a hormone-like translocatable factor from developing fruit that either promotes or inhibits flowering. Extending the time from nut ripening to leaf drop increased production of staminate and distillate flowers the following year and appeared to increase fruit set.
Greenhouse, Detached-leaf, and Field Testing Methods to Determine Cucumber Resistance to Gummy Stem Blight
Authors: Amand Paul C. St. , Wehner Todd C.
Published: January 2019

The effects of leaf age, guttation, stomata and hydathode characteristics, and wounding on the symptom development of gummy stem blight [Didymella bryoniae (Auersw.) Rehm] of cucumber (Cucumis sativus L.) were studied to develop a useful germplasm screening method. Older cucumber leaves were more susceptible than younger leaves in field, greenhouse, and detached-leaf tests. Compared to seedlings with true leaves, seedlings at the cotyledon stage were less susceptible, had a smaller variance for ratings, and were more likely to escape infection. Stomata density and hydathode counts were not correlated with field ratings; but, stomata length on older leaves was highly correlated with susceptibility y. In greenhouse and field tests, susceptibility y increased as guttation increased and actively guttating plants were more susceptible than nonguttating plants. Phylloplane moisture and/or nutrition were more important in the infection process than was stomata] opening. Although important, guttation was not necessary for infection. Dawn inoculation of field or greenhouse tests increased leaf symptoms compared with dusk inoculation. The increase was likely due to the free water and nutrients provided by guttation. Genotype ranks and ratings for detached-leaf tests were not correlated with field results. A useful method, highly correlated (r = 0.82 to 0.96) with field ratings. for screening germplasm in the greenhouse was developed.
Inheritance of Random Amplified Polymorphic DNA (RAPD) Markers in Theobroma cacao L.
Authors: Ronning C.M. , Schnell R.J. , Kuhn D.N.
Published: January 2019

RAPD markers have been used successfully in genetic analysis of several crop plants. This method poses difficulties with a highly heterozygous species such as Theobroma cacao because of the dominant phenotypic expression of bands. A backcross family derived from ctultivars Catongo and Pound 12 was analyzed to determine the efficacy of RAPD markers in analyzing cacao populations. A preliminary screen of the parents and the F1 plant used as the backcross parent was conducted with 180 RAPD primers; of these, 26% were polymorphic and reproducible and produced 104 storable loci. Genomic DNA from 54 individuals of the backcross population was then amplified with these primers; 68.3 % of the loci segregated as expected in a Mendelian fashion. Separation of RAPD fragments on acrylamide revealed an additional polymorphic locus from one primer that was indistinguishable on agarose. The results demonstrated that RAPD markers can be used to study the cacao genome.
Genetic Linkage between Runnering and Phosphoglucoisomerase Allozymes, and Systematic Distortion of Monogenic Segregation Ratios in Diploid Strawberry
Authors: Yu Hongrun , Davis Thomas M.
Published: January 2019

As part of a strawberry (Fragaria sp.) genome mapping project, we studied the linkage relationship between runnering and phosphoglucoisomerase PGI-2 allozymes in diploid strawberry. The respective r and Pgi-2 loci were found linked with a recombination frequency of 18.1% ± 1.6%(a map distance of 18.9 ± 1.6 cM). This is the second reported linkage in strawberry. The linkage between runnering and phosphoglucoisomerase allozymes, if conserved at the octoploid level, might provide a means of marker-assisted selection for the nonrunnering and bushy branching growth habits in cultivated strawberry. Severe distortion of monogenic segregation ratios was observed for runnering and PGI-2, and also for an unlinked locus for shikimate dehydrogenase allozymes. Alleles from the perpetual flowering (alpine F. vesca) parents were favored in this distortion. This phenomenon should be considered in future genetic studies using crosses between alpine and nonalpine strawberries.
Geographical Variation of Growth Rhythm, Height, and Hardiness, and Their Relations in Hippophae rhamnoides
Authors: Yao Yingmou , Tigerstedt Peter M.A.
Published: January 2019

Genetic variation in growth rhythm, hardiness and height of 24 populations from 3 subspecies in sea buckthorn (Hippophae rhamnoides) were studied in a field test. The relative variance component of subspecies varied from 26.2% to 73.7% of total variance. Subspecies turkestanica had a growth mode of late start-late finish, ssp. rhamnoides, intermediate start-early finish and ssp. sinensis, early start-intermediate finish. Subspecies rhamnoides had a growth period of 129 days, ≈30 days shorter than the two Asian subspecies. The average height of ssp. rhamnoides was 43.7 cm, about one-third of that for ssp. tarkestanica and sinensis. Subspecies rhamizoides was more hardy than ssp. sinensis, which was still more hardy than ssp. turkestanica. The variance among populations was generally comparable with within population variance. Except for hardiness, variations for all characters were much larger in ssp. rhamnoides than in ssp. sinensis. The total genetic variance (subspecies plus population) varied from 50% to 84% of total variance for all characters, except 37% for secondbracts. Later growth cessation was correlated with longer growth period, taller plants, more severe frost and winter damage. Strong clinal variation showed that the higher the latitude, the earlier the growth cessation, the shorter the growth period and plant height, the more hardy the population. -The results indicated that population selection should bean efficient way for growth rhythm and plant height. Clinal variation provides guidelines for seed and plant transfer as well as plant introduction. With limited collection and management capacity in germplasm conservation, the recommendation is to collect fewer individuals in each population but more populations along latitude.
Using Randomly Amplified Polymorphic DNA (RAPD) Markers to Identify Annona Cultivars
Authors: Ronning C.M. , Schnell R.J. , Gazit S.
Published: January 2019

The native American genus Annona contains many species that are cultivated for their edible fruit, including the custard apple (A. reticuluta L.), soursop (A. muricata L.), cherimoya (A. cherimola L.), sugar apple (A. squamosa L.), and interspecific hybrids, the atemoyas. RAPD analysis of A. cherimola. `Campa' and `Jete,' A. squamosa `Lessard,' and the atemoyas `Ubranitzki,' `Malali,' and `Kaspi' resulted in very distinctive patterns, indicating that RAPD markers, may be an efficient method of fingerprinting genotypes within and between Annona species. All 15 primers used generated repeatable, polymorphic patterns. An F1 population of `Jete' × `Lessard' was analyzed to determine the inheritance of the RAPD banding patterns. Fifty-two polymorphic loci were identified, which segregated in an expected Mendelian fashion.
Identifying and Mapping Two DNA Markers Linked to the Gene Conferring Resistance to Pea Enation Mosaic Virus
Authors: Yu J. , Gu W.K. , Provvidenti R. , Weeden N.F.
Published: January 2019

Two random amplified polymorphic DNA (RAPD) markers linked to En, the gene conferring resistance to pea enation mosaic virus in pea, were identified and the DNA fragments were cloned and partially sequenced. Allele-specific associated primers for each cloned DNA fragment were developed and used in screening F2 populations. One marker, P256900, mapped very near Adh-1, about 6 cM from En. The other marker, B500400, was located about 8 cM from En on the same side as P256900.
Variation in Randomly Amplified DNA Markers and Storage Root Yield in `Jewel' Sweetpotato Clones
Authors: Villordon Arthur Q. , LaBonte Don R.
Published: January 2019

Polymorphism analysis and yield tests were conducted among `Jewel' sweetpotato clones [Ipomoea batatas (L.) Lam] obtained from eight state foundation seed programs. Initially, 38 arbitrary primers generated a total of 110 scorable DNA fragments in a sample of virus-indexed plants from each clone source. The number of marker loci scored for each primer varied from one to eight with an average of 2.89. Twenty-one bands (19.1%) were scored as putative polymorphic markers based on the presence or absence of amplified products. Further estimation of variability within each clone source was accomplished by an assay of 10 sample plants per clone group by 14 marker loci generated by four selected primers. Polymorphic bands ranged from 7.1% to 35.7 % in five of eight clone groups. Field studies show variation in nearly all yield grades measured. In three tests during the 1991 and 1992 seasons, yield differences ranged from 27% to 46% within the economically important U.S. no. 1 root grade. The results suggest the usefulness of arbitrarily-primed markers in detecting intra-clonal sweetpotato DNA polymorphisms and indicate an underlying genetic cause for phenotypic variability in the crop.
Color Mulches Influence Yield and Insect Pest Populations in Tomatoes
Authors: Csizinszky A.A. , Schuster D.J. , Kring J.B.
Published: January 2019

Field studies were conducted for three seasons, Fall 1988 and Spring and Fall 1989, on the effect of six mulch colors: blue, orange, red, aluminum, yellow, and white (fall) or black (spring), on fruit yields and on insect vectors of Sunny' tomato (Lycopersicon esculentum Mill.). Plant growth and yields were inconsistent with mulch colors during the three seasons. In Fall 1988, in a once-over harvest, extra-large (≥ 70 mm diameter) and marketable fruit yields were higher (P ≤ 0.05) on blue than on the conventional white mulch. In Spring 1989, early marketable yields on red mulch were higher than on black mulch, and in Fall 1989, under high stress from tomato mottle virus (TMoV) transmitted by silverleaf whitefly [Bemisia argentifolii (Bellows and Perring)], seasonal yield of extra-large fruit was better on orange than white mulch. In Fall 1988 and 1989, fruit size and marketable yields were reduced on yellow mulch. Aphids (Aphididae), thrips (Thripidae), and whiteflies were counted monthly in traps placed on the mulched beds. Aphids were least numerous on the aluminum and yellow and most numerous on the blue mulch. Where differences occurred, the fewest thrips were captured on aluminum and the fewest whiteflies were captured on the yellow, aluminum and orange mulches. Although differences were not always significant, the fewest adult whiteflies also were observed on foliage of tomato plants grown on these latter three mulches. Later in the seasons, as plant foliage covered the mulch, differences in the number of insects captured were similar for all mulch colors. Low numbers of whiteflies on the orange and aluminum mulches early in Fall 1989 delayed virus symptom development and increased yields. Virus symptom development was not delayed and yields were low on the yellow mulch, in spite of the low number of whiteflies. When averaged over all mulch colors, extra-large and marketable fruit yields increased linearly with delayed symptom development. It is proposed that, under high insect stress, mulches should be selected for their effects on insects in addition to their effects on soil temperature and plant morphology.
Anatomy of Shuck Abscission in `Desirable' Pecan
Authors: Sparks Darrell , Yates I.E.
Published: January 2019

Cellular changes associated with shuck dehiscence and markings deposited on pecan [Carya illinoinensis (Wangenh.) C. Koch] shells were examined by scanning electron and light microscopy. Fruit were sampled at three stages of maturity: 1) shuck and shell fused, 2) sutures separated (shuck opening), and 3) vascular system separated from shuck. Shuck dehiscence involved temporally regulated abscission events with shuck-shell, then shuck-suture, and finally shuck-vascular system separation. Abscission events occurred in a tissue zone common to and continuous among all three separation sites, even though segregated in time. Also, similar cell types and cellular changes were common to the three events. Thus, temporal segregation of abscission events was not due to differences in either tissue type or cellular modifications, but to maturation rate. Structures to become shell markings were single globules filling cells of the shuck inner tissue zone before shuck-shell separation. These globules were deposited on the shell at shuck-shell separation and were morphologically similar to deposits stuck to the dorsal shuck surface. Globules were partitioned differentially between the shuck and shell during shuck-shell separation. Thus, the inner zone of the shuck is an important tissue in pecan nut maturation; it functions as the site for dehiscence and provides markers for cultivar identification.
Benzyladenine Affects Cell Division and Cell Size during Apple Fruit Thinning
Authors: Wismer Paul T. , Proctor J.T.A. , Elfving D.C.
Published: January 2019

Benzyladenine (BA), carbaryl (CB), daminozide (DM), and naphthaleneacetic acid (NAA) were applied postbloom as fruitlet thinning agents to mature `Empire' apple (Malus domestica Borkh.) trees. BA, NAA, and CB reduced fruit set and yield per tree, and increased fruit size, percent dry weight, soluble solidscontent and return bloom. Fruit size was reduced, return bloom, length: diameter ratio and flesh firmness were increased, and fruit set and yield unaltered by DM. Although fruit set and yield were similar for BA, NAA, and CB, BA treated fruit were larger, indicating that BA increased fruit size beyond the effect attributable to chemical thinning alone. BA increased the rate of cell layer formation in the fruit cortex, indicating that BA stimulated cortical cell division. NAA, CB and DM had no effect on cell division rate. Mean cortical cell diameter at harvest was increased by NAA and CB and reduced by DM. Cell diameter at harvest in BA-treated fruit was similar to the control. These data support the hypothesis that BA-induced fruit size increase in `Empire' apple results from greater numbers of cells in the fruit cortex, whereas the fruit size increase due to NAA or CB is a consequence of larger cell size. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)]; 1-napthaleneacetic acid (NM); 1-naphthalenyl methylcarbamate [carbaryl (CB)]; butanedioic acid mono (2,2dimethyl hydrazide) [daminozide (DM)].
Anatomical Features Facilitating Supercooling of the Flower within the Dormant Peach Flower Bud
Authors: Quamme H.A. , Su Wei Ai , Veto L.J.
Published: January 2019

Excision of the flower from the peach [Prunus persica (L.) Batsch.] flower bud raised the 50% injury temperature of flowers (cooled at 1C/hour) from -18 and -20C to -10 and -13C on two test dates, 26 Feb. 1988 and 5 Dec. 1990, respectively. Ice inoculation of the excised flowers at -3C further raised the 50% injury temperature to -7 and -8C for the two dates, respectively. These observations suggest that supercooling is a true mechanism for avoiding freezing injury. Low temperature scanning electron microscopy of freeze fractured cells verified that the flower froze intracellularly, whereas the subtending tissue froze extracellularly. Ice inoculation of the flower and the flower bud axis from which the scales were removed demonstrated that a barrier to ice propagation (effective to -11C) from the flower bud axis to the flower was present. This barrier may involve the provascular strands and a cell zone at the flower base (BZ) that were devoid of intercellular spaces. These tissues also had smaller cells, smaller vacuoles, greater ratio of cell wall thickness to cell size than tissue just below the BZ, which may result in greater cell rigidity and restriction of extracellular freezing. The cells outside the provascular strands at the base of the flower were also lacking in intercellular space, were smaller in size, and had a higher ratio of cell wall thickness to cell size compared to cells near the base of the scales. In the intact flower buds in which the flowers supercool below -11C, the presence of the first and second scales was important to full expression of supercooling because their removal raised the supercooling point, whereas the removal of lower scales did not. Sequestration of ice by the first two subtending scales during the early stages of freezing may be important to the creation of a dry region at the flower base that prevents ice propagation into the flower at temperatures below -11C.
Browning Potential, Phenolic Composition, and Polyphenoloxidase Activity of Buffer Extracts of Peach and Nectarine Skin Tissue
Authors: Cheng Guiwen W. , Crisosto Carlos H.
Published: January 2019

The relationship of phenolic composition and polyphenoloxidase activity (PPO, E.C. 1.14.18.1) to browning potential (BP) was studied in buffer extracts of peach [Prunus persica L. Batsch) and nectarine [P. persica var. nectarine (L.) Batsch] fruit skin. The BP varied among cultivars with `Flavorcrest' having the highest value and `Maycrest' the lowest. On average, over 83 % of the browning measured at the end of the S-hour incubation occurred during the first hour. The total soluble phenolics (TSP), the total anthocyanin (TA), and glutathione content (GLU) varied among cultivars, but were not significantly correlated to the BP. Of the phenolics determined by HPLC, only chlorogenic acid had a significant positive correlation and epicatechin a significant negative correlation with BP by the first hour of incubation. The PPO activity, ranging from 4 to 11 optical density units per gram dry weight per minute among peaches and nectarines, was not significantly correlated with BP. However, no browning was detected if the buffer extract was previously boiled. These results indicated that browning in the buffer extracts of peach and nectarine skin tissue depends on the presence of PPO activity and chlorogenic acid, which are major contributors to enzymatic browning.
Citrus Scion and Rootstock, Topping Height, and Tree Spacing Affect Tree Size, Yield, Fruit Quality, and Economic Return
Authors: Wheaton T.A. , Whitney J.D. , Castle W.S. , Muraro R.P. , Browning H.W. , Tucker D.P.H.
Published: January 2019

A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions [Citrus sinensis (L.) Osb.], and Milam lemon (C. jambhiri Lush) and Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] rootstocks, tree topping heights of 3.7 and 5.5 m, between-row spacings of 4.5 and 6.0 m, and in-row spacings of 2.5 and 4.5 m. The spacing combinations provided tree densities of 370, 494, 667, and 889 trees ha. Yield increased with increasing tree density during the early years of production. For tree ages 9 to 13 years, however, there was no consistent relationship between yield and tree density. Rusk citrange, a rootstock of moderate vigor, produced smaller trees and better yield, fruit quality, and economic returns than Milam lemon, a vigorous rootstock. After filling their allocated space, yield and fruit quality of trees on Milam rootstock declined with increasing tree density at the lower topping height. Cumulative economic returns at year 13 were not related to tree density.
The Effect of Day and Night Temperature and Irradiance on Development of Catharanthus roseus (L.) `Grape Cooler'
Authors: Pietsch Grace M. , Carlson William H. , Heins Royal D. , Faust James E.
Published: January 2019

The effects of day and night temperatures (15 to 35C) and three irradiance levels [50% of ambient, ambient, and ambient plus 12 mol·m-2·day-1 of supplemental photosynthetic photon flux (PPF)] on development of Catharanthus roseus `Grape Cooler' were determined. Time to flower decreased by 30 days and leaf-pair unfolding rate (LUR) increased linearly as average daily temperature increased from 18 to 35C. Flower size was greatest when plants were grown at 25C. Supplemental light decreased days to flower and increased flower size. Flowering occurred when nine leaf pairs were present on the plant. Using the inverse of the LUR curve, i.e., days per leaf pair, the number of days to flower could be predicted at any time during plant development based on plant leaf number.
Rootstock Effects on the Flowering of `Delicious' Apple. I. Bud Development
Authors: Hirst Peter M , Ferree David C
Published: January 2019

Floral development was studied in buds of `Starkspur Supreme Delicious' apple trees growing on B.9, M.26 EMLA, M.7 EMLA, P.18, and seedling rootstocks. In each of 3 years, buds were sampled from the previous years growth at intervals throughout the growing season and dissected to determine whether the apex was domed, indicating the start of floral development. Number of bud scales and true leaves increased during the early part of the growing season, but remained fairly constant beyond 70 days after full bloom. The type of rootstock did not affect the number of bud scales or transition leaves, and effects on true leaf numbers were small and inconsistent. Final bract number per floral bud was similarly unaffected by rootstock. The proportion of buds in which flowers were formed was influenced by rootstock in only one year of the study, which was characterized by high temperatures and low rainfall over the period of flower formation. Bracts were observed only in floral buds, and became visible after doming of bud apices had occurred. Flowers were formed during the first 20 days in August, regardless of rootstock or year. The appendage number of vegetative buds was constant from 70 days after full bloom until the end of the growing season, but the number of appendages in floral buds increased due to the continued production of bracts. The critical bud appendage number for `Starkspur Supreme Delicious' before flower formation was 20, and was stable among rootstocks and years. Buds with diameters above 3.1 mm were generally floral, but on this basis only 65% of buds could be correctly classified. Spur leaf number, spur leaf area, and spur leaf dry weight were not good predictors of floral formation within the spur bud.
Growth and Topological Changes of Citrus limon (L.) Burm. f. `Eureka' in Response to High Temperatures and Elevated Atmospheric Carbon Dioxide
Authors: Martin Chris A. , Stutz Jean C. , Kimball Bruce A. , Idso Sherwood B. , Akey David H.
Published: January 2019

Growth and topological indices of `Eureka' lemon were measured after 6 months in well-watered and well-fertilized conditions and factorial combinations of moderate (29/21C day/night) or high (42/32C day/night) temperatures and ambient (350 to 380 μmol·mol) or elevated (constant 680 μmol·mol-1) CO2. In high temperatures, plants were smaller and had higher levels of leaf chlorophyll a than in moderate temperatures. Moreover, plants in high temperatures and elevated CO2 had about 15 % higher levels of leaf chlorophyll a than those in high temperatures and ambient CO2. In high temperatures, plant growth in elevated CO2 was about 87% more than in ambient CO2. Thus, high CO2 reduced the negative effect of high temperature on shoot growth. In moderate temperatures, plant growth in elevated CO2 was only about 21% more than in ambient CO2. Irrespective of temperature treatments, shoot branch architecture in elevated CO2 was more hierarchical than those in ambient CO2. Specific shoot extension, a topological measure of branch frequency, was not affected by elevated CO2 in moderate temperatures, but was increased by elevated CO2 enrichment in high temperatures-an indication of decreased branch frequency and increased apical dominance. In moderate temperatures, plants in elevated CO2 had fibrous root branch patterns that were less hierarchical than at ambient CO2. The lengths of exterior and interior fibrous roots between branch points and the length of second-degree adventitious lateral branches were increased >50% by high temperatures compared with moderate temperatures. Root length between branch points was not affected by CO2 levels.
Reducing External Chilling Injury in Stored `Hass' Avocados with Dry Heat Treatments
Authors: Woolf Allan B. , Watkins Christopher B. , Bowen Judith H. , Lay-Yee Michael , Maindonald John H. , Ferguson Ian B.
Published: January 2019

`Hass' avocados (Persea americana Mill.) were heated in air at 25 to 46C for 0.5 to 24 hours and stored at 0, 2, or 6C. After storage, fruit were ripened at 20C and their quality was evaluated. In unheated fruit, external chilling injury occurred in fruit stored at 0 or 2C, hut not 6C. Chilling injury was also evident after storage at 2C in fruit heated at 34C, and to a lesser extent in fruit heated at 36C. A heat treatment (HT) of 38C for 3, 6, or 10 hours and 40C for 0.5 hour further reduced external chilling injury induced by storage at 2C. These HTs did not reduce internal fruit quality and resulted in more marketable fruit than unheated fruit stored at 6C. Low-temperature storage and HT slowed avocado ripening, resulting in longer shelf life after storage. In flesh tissue sampled directly after selected HTs, the levels of mRNA homologous to cDNA probes for two plant heat-shock protein (HSP) genes (HSP17 and HSP70) increased to a maximum at 40C and declined at higher temperatures. These increases in gene expression coincided with the extent to which HTs prevented chilling injury. Hot-air HTs confer significant protection against low-temperature damage to avocados.
Reproductive Characteristics of Pitayo (Stenocereus queretaroensis) and their Relationships with Soluble Sugars and Irrigation
Authors: Pimienta-Barrios Eulogio , Nobel Park S.
Published: January 2019

Flower and fruit production by the columnar cactus, Stenocereus queretaroensis (Weber) Buxbaum, occurred during the dry season in the late winter and spring, and the relatively small annual stem extension occurred primarily during the fall. Thus, reproductive growth does not directly compete with vegetative growth for resources such as reducing sugars, which increased during the wet summer season, a period when total sugars were decreasing. Stem extension, reproductive demography, fruit quality, seed size, and seed quality were not influenced by irrigation. Final fruit size and seed germination, however, were enhanced by applying water. The times from flower bud differentiation to flower opening and from anthesis to fruit ripening were relatively short and unaffected by irrigation.
Controlling Cropping in `Loadel' Cling Peach Using Gibberellin: Effects on Flower Density, Fruit Distribution, Fruit Firmness, Fruit Thinning, and Yield
Authors: Southwick Stephen M. , Weis Kitren G. , Yeager James T. , Zhou Hong
Published: January 2019

Whole-tree sprays of Release LC [predominantly gibberellic acid] (GA,) were applied in a commercial peach [Prunus perisca (L.) Batsch.] orchard in the California Central Valley on three dates from mid-June (about 90 days after full bloom = 28 days before harvest) to late July (14 days postharvest) 1993 at 50, 75, 100, and 120 mg·liter-1. Gibberellin (GA) reduced the number of flowers differentiated in 1993, thereby reducing fruit density in 1994, when sprays were applied by early July 1993. Sprays in late July did not reduce flowering and fruiting density in the following year. In 1994, there were fewer fruit located on the proximal third of the shoot after GA sprays of 75,100, and 120 mg-liter' applied on 15 June compared to hand-thinned controls, and reduction was linear with increase in GA rate. Fruit numbers in the middle and distal sections of shoots were reduced by all 15 June and some 9 July GA sprays, with fewer fruit as concentration increased. However, the distribution of fruit within shoot sections, after GA treatments during floral differentiation, expressed as a percentage of the total number of fruit along fruiting shoots, showed even fruiting compared with hand thinning. Due to reduced flowering in response to GA treatments in June and early July 1993, the hand-thinning requirement was significantly reduced, with no thinning required in 1994 from 15 June 1993 GA sprays. All sprays applied in early July resulted in 40% to 60% fewer fruit removed during thinning than the nontreated controls. Sprays in late July were ineffective. Sprays of GA applied in mid-June at 50,75, 100, and 120 mg·liter and sprays of 120 mg·liter-1 GA applied in early July (4 days preharvest) increased the firmness of `Loadel' cling peach (about 26% improvement in June sprays) in 1993. The salable yield of fruit (after removal of the undersized fruit) was the same on hand thinned and on non-hand thinned trees treated with GA on 15 June at 50 mg·liter-1. The salable yield of fruit was increased by GA sprays of 50 and 75 mg·liter applied on 9 July 1993 compared to controls. There were no differences in fruit size (by weight or diameter) among the aforementioned treatments and hand thinning. GA sprays of 75,100, and 120 mg-liter' applied on 15 June 1993 tended to reduce salable yield, but fruit size increased with decreased yield. Based on the results obtained in 1993 and 1994, we believe that Release LC has good potential for chemically thinning peaches in California.
A New Recessive Allele at the C Locus for Seedcoat Color in Common Bean
Authors: Bassett Mark J.
Published: January 2019

The inheritance of a new allele, cv, at the C locus for seedcoat color was studied in common bean (Phaseolus vulgaris L.) using plant introduction (PI) accession 527774 as the source of cv. The cross PI 527774 (yellow-brown seed) x v BC25-593 (mineral-brown seed) genetic tester stock was studied in F1 and F2 progeny. An F3 selection from the above cross, designated F3 cv G b v, was crossed to 5-593 (a Florida breeding line with black seeds), and the F1, and F2 progeny were analyzed for color segregation. The second hackcross [S-593 x F1 (F3 cv G b v x 5-593)] was investigated in selfed progenies from 32 random BC2-F1 parents. Two of the BC2-F2 progenies were further tested in BC2,-F3. A third hackcross of cv to 5-593 was made and analyzed, and an allelism test of cv B V BC2-F35-593 with the cartridge huff cu BC3 5-593 genetic tester stock confirmed that cv is an allele at C. The gene symbol, cv, is proposed for the new allele because it is only expressed with V and gives a grayish-brown seedcoat. Genotypes with C/cv do not show heterozygous mottling with G B v or G b v, and there is no difference in seedcoat color between C G B v and cv G B v, or between C G b v and cv G b v.
Transfer and Transcriptional Expression of Coleopteran cryIIIB Endotoxin Gene of Bacillus thuringiensis in Eggplant
Authors: Chen Qi , Jelenkovic Gojko , Chin Chee-Kok , Billings Sharon , Eherhardt Jodi , Goffreda Joseph C. , Day Peter
Published: January 2019

Three constructs of a coleopteran toxic cryIIIB Bacillus thuringiensis gene were engineered and incorporated into eggplant (Solanum melongena L.). Southern blot analysis of the eight primary transformants and segregational analysis of their R, progenies indicated that the chimeric cryIIIB constructs in each of the transgenic plants were stably incorporated at a single locus or at multiple sites within the same linkage group and that they were regularly transmissible to the progeny. The results of Northern blot and RNase protection analyses demonstrated that transcription of the cryIIIB mRNA takes place in plant cells, but only a small amount of the expected entire length transcripts were produced. The amount of the 5' end mRNA fragment produced was at least 30 to 40 times more abundant than the amount of the 3' end mRNA fragment. This could be interpreted to mean that either the two ends of the mRNA are of different stability or that the transcription process is often interrupted and only a few mRNAs complete the entire process to the end. When the transgenic plant mRNA was reverse-transcribed, amplified by polymerase chain reaction, and hybridized to the cryIIIB probe, two smaller molecular weight mRNA species were identified. Thus, the preponderance of the cryIIIB mRNA in transgenic plants exists as a truncated species, a situation similar to that of cryI genes when expressed in transgenic plants. Seedlings from the eight independent transgenic plants were tested for Coleopteran insect resistance. However, they did not demonstrate any significant resistance to the first and second instar larvae of the Colorado potato beetle (Leptinotarsa decemlineata Say).