bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetics of Apical Dominance in Plantain (Musa spp., AAB Group) and Improvement of Suckering Behavior
Authors: Ortiz Rodomiro , Vuylsteke Dirk R.
Published: January 2019

Apical dominance, i.e., the inhibition of lateral bud growth due to growth substances released by the terminal bud, has been considered as a limiting factor for the perennial productivity of plantains (Musa spp., AAB group). Segregation ratios in F1 and F2 plantain-banana hybrids suggest that inheritance of apical dominance is controlled by a major recessive gene, ad. The dominant Ad allele improved the suckering of plantain-banana hybrids, as measured by the height of the tallest sucker at flowering and harvest. At harvest, the ratoon crop of the diploid and tetraploid hybrids had completed 70% to 100% of its vegetative development, whereas the ratoon of the plantain parents, due to high apical dominance, was only at 50% of total pseudostem growth. Sucker growth rates are generally the result of gibberellic acid (GA3) levels, and it is suggested that the Ad gene regulates GA3 production. However, the Ad gene has incomplete penetrance, genetic specificity, and variable expressivity. Increased frequency of the Ad gene and a commensurate improvement in the suckering behavior of the diploid populations may be achieved by phenotypic recurrent selection.
Genetic Analysis of the Green Cotyledon Trait in Southernpea [Vigna unguiculata (L.) Walp.]
Authors: Fery Richard L. , Dukes Philip D.
Published: January 2019

A series of greenhouse and field studies were conducted to determine the inheritance of the green cotyledon trait exhibited by the recently released southernpea `Bettergreen' and to elucidate the genetic relationship between the green cotyledon trait and the green testa trait exhibited by `Freezegreen'. Evaluation of parental, F1, F2, and backcross populations of the crosses `Bettergreen' × `Carolina Cream' and `Bettergreen' × `Kiawah' indicated that the green cotyledon trait is conditioned by a single recessive gene. Evaluation of parental and F2 populations of the cross `Bettergreen' × `Freezegreen' indicated that this gene is neither allelic to nor linked with the gt gene that conditions the green testa trait in `Freezegreen'. The color of seeds harvested from plants homozygous for both the green cotyledon and green testa genes was superior and more uniform than the color of seeds harvested from either `Bettergreen' or `Freezegreen' plants. We propose that the newly discovered gene be designated green cotyledon and symbolized gc. Seeds containing embryos homozygous for the gc gene are easily identified. The ability to select in the seed stage should greatly facilitate efforts to backcross the gc gene into cream-, pinkeye-, and blackeye-type cultivars.
Determining Yellow-flesh Intensity in Potatoes
Authors: Haynes Kathleen G. , Potts William E. , Chittams Jesse L. , Fleck Diane L.
Published: January 2019

For the yellow-flesh fresh market, potato (Solanum tuberosum L.) varieties with intense yellow flesh are desired. Twenty-five yellow-flesh clones, including 24 U.S. Dept. of Agriculture (USDA) selections and the check variety `Yukon Gold', were evaluated for tuber yellow-flesh color, as measured by a reflectance colorimeter, and for individual tuber weight in replicated field trials in Presque Isle, Maine, in 1991 and 1992. There were significant differences among clones for yellow-flesh intensity. Yellow-flesh intensity in two USDA selections was significantly less than in `Yukon Gold'. In four USDA selections, yellow-flesh intensity was significantly greater than in `Yukon Gold'. In general, there was an inverse relationship between tuber weight and yellow-flesh intensity. Subsamples of tubers whose weight fell between the 10 to 90, 25 to 75, 35 to 65, and 40 to 60 percentile were compared to the full sample. There was good agreement between the 10 to 90 and 25 to 75 percentile subsample and the full sample regarding the average yellow-flesh intensity and in the consistency of pairwise comparisons between individual selections and `Yukon Gold'. For determining yellow-flesh intensity, the 25 to 75 percentile subsample was as informative as the full sample.
ACC-derived Ethylene Production, a Sensitive Test for Seed Vigor
Authors: Khan Anwar A.
Published: January 2019

ACC-derived ethylene production was used as an index of seed vigor of lettuce (Lactuca sativa L.), cabbage [Brassica oleracea (Capitata Group)], tomato (Lycopersicon esculentum Mill.), snap bean (Phaseolus vulgaris L.), and sweet corn (Zea mays L.) seeds. Seeds were aged at 40C and 93% relative humidity over saturated solution of KH2PO4 for various times to obtain seeds of differing vigor. Naturally aged lettuce seeds, differing in vigor, were also used. Depending on the seed type, 0.25 to 2 mm ACC (saturating dose) was needed to produce maximal amounts of ethylene. Seeds in the presence of ACC produced a much larger amount of ethylene than those in the absence of ACC, the ACC-derived ethylene could be detected before germination, and ACC had no adverse effect on germination. ACC-derived ethylene production paralleled vigor loss as determined by a decrease in percentage germination over a soak period required for complete germination of nonaged seeds (16 hours for lettuce, 24 hours for cabbage, and 48 hours for tomato and sweet corn), an increase in mean germination time (determined for lettuce only), and a decrease in seedling growth (determined for snap bean only). Second degree polynomial and logarithmic equations generated for the relationship of ACC-derived ethylene production to germination or growth parameters following seed aging, provided good to excellent fit. As a vigor test, the ACC-ethylene procedure has several advantages over the non-ACC ethylene procedure: It improves the sensitivity of the test by enhancing ethylene production, permits detection of small differences in vigor, and allows detection of ethylene before germination within a few hours of soaking. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Suitability of Prunus Selections as Hosts for the Ring Nematode (Criconemella xenoplax)
Authors: Westcott S.W. , Zehr E.I. , Newall W.C. , Cain D.W.
Published: January 2019

Prunus accessions were screened in a greenhouse for suitability as hosts for Criconemella xenoplax (Raski) Luc and Raski. All 410 accessions examined were suitable hosts for the nematode. Included in this study were 266 Prunus persica L. Batsch cultivars and cultivars representing 25 other Prunus species: P. americana Marsh., P. andersonii A. Gray, P. angustifolia Marsh., P. argentea (Lam.) Rehd., P. armeniaca L., P. besseyi L. H. Bailey, P. cerasifera Ehrh., P. cistena N.E. Hansen, P. davidiana (Carriere) Franch., P. domestica L., P. dulcis (Mill.) D. Webb, P. emarginata (Dougl. ex Hook.) Walp., P. hortulana L. H. Bailey, P. insititia L., P. kansuensis Rehd., P. maritima Marsh., P. munsoniana W. Wright & Hedr., P. pumila L., P. salicina Lindl., P. simonii Carriere, P. spinosa L., P. tenella Batsch, P. texana D. Dietr., P. tomentosa Thunb., and P. webbii (Spach) Vierh. Also, another 66 interspecific hybrids were tested. Although a few accessions seemed to exhibit an unstable form of resistance, it seems unlikely that Prunus selections that exhibit useful resistance to population increase by C. xenoplax will be found.
Nutrient Uptake by Cropping and Defruited Field-grown `French' Prune Trees
Authors: Weinbaum S.A. , Niederholzer F.J.A. , Ponchner S. , Rosecrance R.C. , Carlson R.M. , Whittlesey A.C. , Muraoka T.T.
Published: January 2019

Four adjacent heavily cropping 12-year-old `Petite d'Agen' prune (Prunus domestica L.) trees were selected, and two of the trees were defruited in late spring (28 May) after the spring growth flush and full leaf expansion. Trees received K daily through the drip-irrigation system, and 15N-depleted (NH4)2SO4 was applied twice between the dates of defruiting and fruit maturation. Trees were excavated at the time of fruit maturity (28 July) and fractionated into their component parts. The following determinations were made after tree excavation and sample processing: tree dry weight, dry weight distribution among the various tree fractions (fruit, leaves, roots, trunk, and branches), tree nutrient contents, within-tree nutrient distribution, total nonstructural carbohydrates (TNCs), and recovery of labeled N. Trees only recovered ≈3% of the isotopically labeled fertilizer N over the 6-week experimental period. Heavily cropping trees absorbed ≈9 g more K per tree (17% of total tree K content) during the 2-month period of stage III fruit growth than defruited trees. The enhanced K uptake in heavily cropping trees was apparently conditioned by the large fruit K demand and occurred despite greatly reduced levels of starch and TNCs relative to defruited trees. Fruit K accumulation in heavily cropping trees was accompanied by K depletion from leaves and perennial tree parts. Except for K, fruited and defruited trees did not differ in nutrient content.
Physiology of Olive Leaf Abscission Induced by Phosphorus
Authors: Yamada Hisashi , Martin George C.
Published: January 2019

Adding Al2O3 to 8-hydroxyquinoline citrate (8-HQC) solution did not alter the sensitivity of the leaf abscission zone to external ethylene. Exogenous ethylene at 791 nl·liter-1 for 72 to 120 hours and at 193 nl·liter-1 for 120 hours induced leaf abscission, whereas no leaf abscission occurred at 47 nl·liter-1 for 72 to 120 hours. Ethylene at 791 nl·liter-1 for 72 to 120 hours increased ethylene evolution, but the amount of ethylene evolved from the explants does not seem to be enough to induce leaf abscission. Three different ethylene inhibitors—aminooxyacetic acid (AOA), CoCl2, and aminoethoxyvinylglycine (AVG)—were used to determine whether P-induced leaf abscission was mediated through elevated ethylene evolution. Although AOA and CoCl2 failed to inhibit ethylene evolution from the explants stem-fed with NaH2PO4, AVG inhibited ethylene evolution. Each inhibitor, except 5 mm CoCl2, promoted leaf abscission when administered alone or with P. Our results reveal that P-induced olive leaf abscission may occur without elevated ethylene evolution. At 40 or 75 mm NaH2PO4, abscission did not occur until explants were removed from N2 and placed in ambient air.
Water Loss: A Nondestructive Indicator of Enhanced Cell Membrane Permeability of Chilling-injured Citrus Fruit
Authors: Cohen E. , Shapiro B. , Shalom Y. , Klein J.D.
Published: January 2019

Water loss was found to be a nondestructive indicator before visible symptoms of chilling injury (CI) in cold-stored grapefruit (Citrus paradisi Macf.) and lemon (C. limon L. Burm. f.). The water-loss rate increased significantly after removing the fruit from cold storage and holding at 20C. Scanning electron microscopy revealed large cracks around the stomata. Changes in electrical conductivity of the flavedo tissues, total electrolyte leakage, and K+ or Ca2+ leakage were all inadequate predictors of CI, appearing only after CI was evident.
Yield and Seed Oil Content Response of Dwarf, Rapid-cycling Brassica to Nitrogen Treatments, Planting Density, and Carbon Dioxide Enrichment
Authors: Frick Jay , Nielsen S. Suzanne , Mitchell Cary A.
Published: January 2019

Effects of N level (15 to 30 mm), time of N increase (14 to 28 days after planting), and planting density (1163 to 2093 plants/m2) were determined for crop yield responses of dwarf, rapid-cycling brassica (Brassica napus L., CrGC 5-2, Genome: ACaacc). Crops were grown in solid-matrix hydroponic systems and under controlled-environment conditions, including nonsupplemented (ambient) or elevated CO2 concentrations (998 ± 12 μmol·mol-1). The highest seed yield rate obtained (4.4 g·m-2·day-1) occurred with the lowest N level (15 mm) applied at the latest treatment time (day 28). In all trials, CO2 enrichment reduced seed yield rate and harvest index by delaying the onset of flowering and senescence and stimulating vegetative shoot growth. The highest shoot biomass accumulation rate (55.5 g·m-2·day-1) occurred with the highest N level (30 mm) applied at the earliest time (day 14). Seed oil content was not significantly affected by CO2 enrichment. Maximum seed oil content (30% to 34%, dry weight basis) was obtained using the lowest N level (15 mm) initiated at the latest treatment time (day 28). In general, an increase in seed oil content was accompanied by a decrease in seed protein. Seed carbohydrate, moisture, and ash contents did not vary significantly in response to experimental treatments. Effects of N level and time of N increase were consistently significant for most crop responses. Planting density was significant only under elevated CO2 conditions.
Winter Application of Low-biuret Urea to the Foliage of `Washington' Navel Orange Increased Yield
Authors: Ali Anwar G. , Lovatt Carol J.
Published: January 2019

The objective of this study was to test whether a single winter prebloom foliar application of low-biuret urea would increase the yield of 30-year-old `Washington' navel orange trees [Citrus sinensis (L.) Osbeck] on Troyer citrange rootstock [C. sinensis `Washington' × Poncirus trifoliata (L.) Raf.]. All trees received a winter (November to January) soil application of urea (0.5 kg N/tree). Trees were maintained under irrigation or irrigation was withheld from 1 Oct. to 1 Mar. To determine the optimal time for foliar urea application, trees in both irrigation main plots received one application of low-biuret urea in mid-November, mid-December, mid-January, or mid-February applied at a rate of 0.16 kg N/tree. There was a set of control trees that only received the soil application of urea. Trees receiving foliar-applied urea in mid-January or mid-February, independent of irrigation treatment, had significantly greater yield and fruit number per tree each year than the control trees for 3 consecutive years. The number of fruit with diameters of 6.1 to 8.0 cm increased significantly as yield increased (r2 = 0.88). Withholding irrigation from 1 Oct. to 1 Mar. had a negative impact on yield. Annual winter application of low-biuret urea to the foliage did not significantly increase leaf total N at the end of 3 years.
Growth, Carbon Acquisition, and Source-Sink Relationships in `Titan' Red Raspberry
Authors: Fernandez Gina E. , Pritts Marvin P.
Published: January 2019

Seasonal changes in growth, mean maximal photosynthetic rates, and the temperature and light response curves of `Titan' red raspberry (Rubus idaeus L.) were obtained from potted plants grown under field conditions. Primocane dry weight accumulation increased steadily at the beginning and the end of the season, but growth slowed midseason during fruiting. The slower midseason dry-weight accumulation rate coincided with an increase in root dry weight. Primocane net assimilation rate (NAR) was highest early in the season. Floricane photosynthetic rates (A) were highest during the fruiting period, while primocane A remained steady throughout the season. Primocane and floricane leaflets displayed a midday depression in A under field conditions, with a partial recovery in the late afternoon. Photosynthetic rates of primocane and floricane leaves were very sensitive to temperature, exhibiting a decline from 15 to 40C. Light-response curves differed depending on cane type and time of year. A temporal convergence of sink demand from fruit, primocanes, and roots occurs when plants experience high temperatures. These factors may account for low red raspberry yield.
Effect of Preharvest Fruit Temperature on Ripening, Sugars, and Watercore Occurrence in Apples
Authors: Yamada Hisashi , Ohmura Hirokazu , Arai Chizuru , Terui Makoto
Published: January 2019

The influence of controlling temperature during apple (Malus domestica Borkh.) maturation on sugars, fruit maturity, and watercore occurrence was investigated in watercore-susceptible `Himekami' and `Fuji' apples. The incidence of watercore at 13/5 and 23/15C was greater than at 33/25C or ambient temperatures in `Himekami' apples in 1991 and was greater at 18/10C than at other temperatures in `Fuji' apples in 1990. In 1992, the extent of watercore increased as fruit temperature decreased from 28 to 14C and 23 to 9C in `Himekami' and `Fuji' apples, respectively. Watercore occurrence affected by fruit temperature was not related to fruit maturity, as judged by ethylene evolution. The effect of fruit temperature on sorbitol was relatively small compared with that on other sugars, and no relationship was found between watercore development and sugars. These results suggest that fruit temperature affects watercore expression independently of fruit maturity or sorbitol metabolism in the fruit in watercore-susceptible apple cultivars.
Adapting Constant-volume Manometry for Studying Gas Exchange by Bulky Plant Organs
Authors: Nery Amauri Alves , Calbo Adonai Gimenez
Published: January 2019

Constant-pressure manometry, previously designed to study O2 and CO2 gas exchange in small pieces of tissue, cells, and organelles, was adapted to study bulky organs. According to this new procedure, a near-zero-volume Devaux chamber connects a manometer to the internal atmosphere volume (VG) of a plant organ covered by a layer of epoxy, submerged in unstirred water, kept at constant temperature, and kept at the same VG pressure. Equations, based on CO2 and O2 solubility at equilibrium with VG, were used to follow O2 consumption as a function of reduced internal O2 pressure over time [for organs with VG < 0.1 (v/v) and respiratory quotient (RQ) of 0.7 to 1.3] to observe the transition between aerobiosis and anaerobiosis and to measure CO2 evolution during the anaerobic phase. For those measurements, bulky-organ manometry performed consistently in tomato [VG = 6.41% (v/v)], sweetpotato [VG = 8.57% (v/v)], and potato [VG = 0.34% (v/v)]. The results indicate that constant-volume manometry is sufficiently precise to detect differences in respiratory metabolism as a function of intercellular O2 concentration in intact plant organs.
Novel Gaseous Ethylene Binding Inhibitor Prevents Ethylene Effects in Potted Flowering Plants
Authors: Serek Margrethe , Sisler Edward C. , Reid Michael S.
Published: January 2019

A 6-hour fumigation of flowering Begonia ×elatior hybrida Fotsch. `Najada' and `Rosa', B. ×tuberhybrida Voss. `Non-Stop', Kalanchoe blossfeldiana Poelln. `Tropicana', and Rosa hybrida L. `Victory Parade' plants with 1-MCP, (formerly designated as SIS-X), a gaseous nonreversible ethylene binding inhibitor, strongly inhibited exogenous ethylene effects such as bud and flower drop, leaf abscission, and accelerated flower senescence. The inhibitory effects of 1-MCP increased linearly with concentration, and at 20 nl·liter-1 this compound gave equal protection to that afforded by spraying the plants with a 0.5 STS mm solution. Chemical names used: 1-methylcyclopropene (1-MCP), silver thiosulfate (STS).
The Effect of Protein Synthesis Inhibition on Petal Senescence in Cut Bulb Flowers
Authors: Jones Rodney B. , Serek Margrethe , Kuo Chen-Lan , Reid Michael S.
Published: January 2019

Petal opening and senescence of cut Gladiolus, Iris, and Narcissus flowers was significantly inhibited by continuous treatment with 1 mm CHI. Vase life was doubled in individual flowers treated when half-open, and a similar effect was detected after pulsing cut gladiolus spikes with 1 mm CHI for 24 hours. Petal wilting was markedly inhibited in flowers treated with CHI and was confined to the outer 2 to 3 mm of petal margins as opposed to the entire petal in untreated flowers. These effects were not seen, however, in CHI-treated cut tulip flowers, where vase life was significantly reduced. CHI markedly inhibited protein synthesis in Gladiolus `New Rose' florets (a decrease of >60%). Treatment with a potent biocide, DICA, did not increase vase life; therefore, CHI was not prolonging flower longevity by preventing microbial growth in the vase solution. The results indicate that de novo protein synthesis is required for bulb flower development and opening and petal wilting and senescence. Chemical names used: cycloheximide (CHI), sodium dichloroisocyanuric acid (DICA).
Net Carbon Dioxide Exchange Rates and Predicted Growth Patterns in Alstroemeria `Jacqueline' at Varying Irradiances, Carbon Dioxide Concentrations, and Air Temperatures
Authors: Leonardos E.D. , Tsujita M.J. , Grodzinski B.
Published: January 2019

The influence of irradiance, CO2 concentration, and air temperature on leaf and whole-plant net C exchange rate (NCER) of Alstroemeria `Jacqueline' was studied. At ambient CO2, leaf net photosynthesis was maximum at irradiances above 600 μmol·m-2·s-1 photosynthetically active radiation (PAR), while whole-plant NCER required 1200 μmol·m-2·s-1 PAR to be saturated. Leaf and whole-plant NCERs were doubled under CO2 enrichment of 1500 to 2000 μl CO2/liter. Leaf and whole-plant NCERs declined as temperature increased from 20 to 35C. Whereas the optimum temperature range for leaf net photosynthesis was 17 to 23C, whole-plant NCER, even at high light and high CO2, declined above 12C. Dark respiration of leaves and whole plants increased with a Q10 of ≈2 at 15 to 35C. In an analysis of day effects, irradiance, CO2 concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER explained by a second-order polynomial model (R2 = 0.85). Interactions among the factors accounted for 4% of the variation in day C assimilation. The potential whole-plant growth rates during varying greenhouse day and night temperature regimes were predicted for short- and long-day scenarios. The data are discussed with the view of designing experiments to test the importance of C gain in supporting flowering and high yield during routine harvest of Alstroemeria plants under commercial greenhouse conditions.
Isozyme Locus Pgm-1 Is Tightly Linked to a Gene (Vf) for Scab Resistance in Apple
Authors: Manganaris A.G. , Alston F.H. , Weeden N.F. , Aldwinckle H.S. , Gustafson H.L. , Brown S.K.
Published: January 2019

Pgm-1, the gene responsible for variation in the most anodal isozyme of phosphoglucomutase in apple (Malus spp.), is shown to lie ≈8 centiMorgans from the gene Vf, which confers apple-scab resistance. The proximity of the marker and the ease by which allozymic forms can be resolved suggest that Pgm-1 will be useful for following the inheritance of scab resistance conferred by Vf.
Genetic Analysis of Japanese Persimmon Fruit Weight
Authors: Yamada M. , Yamane H. , Ukai Y.
Published: January 2019

The expected proportion of individuals in progeny having genotypic values for fruit weight over a given selection criterion to the total individuals derived from a cross was estimated by multiple-regression analysis in which inbreeding coefficient (F) and midparental (MP) value were independent variables and progeny mean was the dependent variable in Japanese persimmon (Diospyros kaki Thunb.). A total of 117 seedlings from 39 crosses was used. Genetic differences of progenies among crosses could be explained solely by F and MP, the effect of the former being greater than the latter. The expected proportion of progenies with large fruit decreased as MP decreased and severely decreased as F increased. Based on the parental mean of 35 fruit on a single tree for 3 years, the proportion of individuals in progeny with fruit weight >200 g was estimated as 34%, 21%, and 12% for 0, 0.125, and 0.25 F values, respectively, in individual from a cross with MP = 200 g.
Genetically Diverse Peach Seedling Rootstocks Affect Long-term Performance of `Redhaven' Peach on Fox Sand
Authors: Layne Richard E.C. , Jui Perry Y.
Published: January 2019

Ten genetically diverse peach [Prunus persica (L.) Batsch] seedling rootstocks were studied for 10 years on Fox sand using `Redhaven' as the scion. The purpose of the experiment was to assess the performance of three Harrow Research Station (Ont.) hybrid selections (H7338013, H7338016, and H7338019) and two northern China introductions (`Chui Lum Tao' and `Tzim Pee Tao') against five commercial standards, two of which were selected in Canada (`Harrow Blood' and `Siberian C') and three in the United States (`Bailey', `Halford', and `Lovell'). Rootstock performance was assessed indirectly by measuring or subjectively rating various aspects of scion performance including annual trunk cross-sectional area (TCA); final tree height, spread, and TCA; bloom and fruit set intensity; yield and yield efficiency; canker (Leucostoma spp.) severity; defoliation rate; winter injury; cold hardiness of flower buds and shoot xylem; and tree survival. Rootstock effects on the above measurements and ratings were significant in some years and not in others. Year effects were always large and significant, while rootstock × year interactions were usually small and not significant. In the combined analyses over years, the largest rootstock effects were obtained for bloom, fruit set, and defoliation ratings and for TCA measurements. Three cumulative responses, including marketable yields, yield efficiency, and tree survival, were used for comparing the five experimental rootstocks with the five commercial standards and also for ranking the 10 rootstocks with respect to each other to assess their potential commercial value as peach rootstocks. `Chui Lum Tao', H7338013, and `Bailey' had the most commercial potential for southern Ontario because they typically promoted above average cumulative yield, yield efficiency, and tree survival. `Tzim Pee Tao', `Siberian C', and `Harrow Blood' were less valuable, with low cumulative marketable yields. `Halford' and `Lovell' were the least valuable, with the lowest tree survival (17%). Performance of H7338013 exceeded that of both parents (`Bailey' and `Siberian C'), H7338019 exceeded `Siberian C' but not `Bailey', while performance of H7338016 was inferior to both parents. Wider testing of the experimental rootstocks on different soil types and climatic zones is needed.
Morphological Characterization and Classification of Open-pollinated Sweet Corn Cultivars
Authors: Revilla Pedro , Tracy W.F.
Published: January 2019

Sweet corn is one of the most important vegetable crops in the United States, however the morphology and phylogeny of open-pollinated sweet corn cultivars has not been studied. Fifty eight open-pollinated sweet corn cultivars were characterized with thirty-four descriptors to provide information for breeders interested in broadening the genetic base of sweet corn. Principal component analysis and cluster analysis were performed to classify sweet corn cultivars based on morphology. Also, relationships among morphological variables in this set of cultivars were determined. The general ordination of cultivars followed an axis representing earliness, and plant, leaf, and tassel size, while ear and kernel attributes were less variable. The morphological variability among all of the widely used sweet corn cultivars, except `Country Gentleman', was not greater than the variability found among the `Golden Bantam' strains. Based on morphology, 52 of the cultivars could be considered as one race, which we propose be called `Northeastern Sweets'. These may be a subset of the race `Northern Flint'. Five of the remaining cultivars are from the north-central or southwestern United States and may represent races from those areas. The sixth cultivar is `Country Gentleman', a commercially important sweet corn cultivar. Due to the importance of `Country Gentleman' and the introgression of nonsweet germplasm into modern sweet corn, we believe that sweet corn should be defined based on its use as a vegetable and on the presence of one or more genes that increase sugar levels in the endosperm.
Seedcoat Structure Related to Germination in Eastern Redbud (Cercis canadensis L.)
Authors: Jones Rodney O. , Geneve Robert L.
Published: January 2019

The seedcoat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud (Cercis canadensis L.). A discontinuous area was observed between macrosclereid cells in the palisade layer of the seedcoat which formed a hilar slit. A cap was formed during germination as the seedcoat separated along the hilar slit and was hinged by the macrosclereids in the area of the seedcoat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seedcoat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seedcoat between dormant and nondormant imbibed seeds. However, the thickened mesophyll of the seedcoat in this region and the capacity of the endosperm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.
Retention and the Kinetics of Uptake and Export of Foliage-applied, Labeled Boron by Apple, Pear, Prune, and Sweet Cherry Leaves
Authors: Picchioni G.A. , Weinbaum S.A. , Brown P.H.
Published: January 2019

Leaf retention, uptake kinetics, total uptake (per unit leaf area), export kinetics, and the total export of foliage-applied, labeled B (]0B-enriched boric acid) were determined for apple (Malus domestics Borkh.), pear (Pyrus communis L.), prune (Prunus domestics L.), and sweet cherry (P. avium L.). Foliar uptake of labeled B by shoot leaves was 88% to 96% complete within 24 hours of application. More than 50% of the B retained on shoot leaf surfaces following application was absorbed and exported within 6 hours of application. Genotypic differences in shoot leaf surface characteristics among the species tested greatly influenced the amount of solution retained per unit leaf area. Leaf retention capacity was the primary determinant of the quantity of B absorbed by and exported from shoot leaves following foliar application. On average, apple shoot leaves retained, absorbed, and exported at least twice as much labeled B per unit leaf area as prune and pear shoot leaves and three to four times as much as sweet cherry shoot leaves. The sink demand of nearby, mature apples did not affect the export of labeled B when applied to adjacent spur leaves, but the fruit imported 16% of their total B from the applied solution during a 10-day period. Despite extensive documentation for the immobility of B accumulated by leaves naturally (e.g., from the soil), the B accumulated by leaves following foliage application was highly mobile in all four species tested.
Water Stress- and Nutrient Solution-mediated Changes in Water Relations and Amino Acids, Organic Acids, and Sugars in Xylem Fluid of Prunus salicina and Lagerstroemia indica
Authors: Andersen Peter C. , Brodbeck Brent V. , Mizell Russell F.
Published: January 2019

The effects and interactions of water stress and nutrient solution on water relations and concentrations of amino acids, organic acids and sugars in xylem fluid of `Methley' plum (Prunus salicina Lindl.) and `Carolina Beauty' crape myrtle (Lagerstroemia indica L.) during midday were determined. Container-grown plants were irrigated with water or nutrient solution (i.e., osmolarity = 138 mm) for 15 days, then irrigation was either continued or terminated for the next 5 days. The experiments were analyzed as factorial designs for each species separately, with the nutrient solution and irrigation status the last 5 days as the main factors. Xylem fluid tension increased ≈ 2- to 3-fold and leaf conductance to water vapor and transpiration were reduced ≈ 10-fold by withholding irrigation for both species; plant water relations of L. indica were also influenced by the nutrient solution. For both species, the osmolarity of xylem fluid was not altered by withholding irrigation. The predominant organic compounds quantified in both species were amides (i.e., glutamine and asparagine), arginine, and citric and malic acids. Sugars represented a small proportion (i.e., generally ≤ 1%) of total osmolarity. Irrigation altered the chemical profile of amino acids and organic acids to a greater degree than the nutrient solution. Water stress induced a 3-fold increase in total organic acids in xylem fluid of both species. The osmolarity and the concentration of most organic compounds in xylem fluid of P. salicina were not significantly affected by the nutrient solution. Arginine increased markedly in concentration by withholding irrigation or with the application of nutrient solution for L. indica. The concentration of most organic compounds did not vary greatly in response to variations in soil water or nutrient status. In conclusion, soil water-or nutrient-mediated changes in plant water relations exceeded changes in xylem fluid chemistry.
Fruiting Stress Induces Shuck Decline and Premature Germination in Pecan
Authors: Sparks Darrell , Reid William , Yates I.E. , Smith Michael W. , Stevenson Thomas G.
Published: January 2019

The influence of fruiting stress on shuck decline, nut quality, and premature germinaiton was evaluated on trees of pecan [Carya illinoensis (Wangenh.) C. Koch]. Fruit at the liquid endosperm state were removed from trees with a mechanical shaker to reduce crop load by 0%, 25%, 41%, 56%, or 77%. Shuck decline and premature germination decreased and kernel quality increased with a reduction in crop load. An excessive fruit load or fruit stress elevated the incidence of shuck decline, previously referred to as shuck disease, tulip disease, shuck die-back, or late season shuck disorder; decreased kernel development; and increased premature germinaiton. Shucks were dissected from fruit ranging from healthy to those with premature shuck opening and examined by scanning electron, transmission electron, and light microscopy. Fungal growth was detectable, but only after tissue degeneration had occurred. Thus, results indicate the onset of shuck decline is caused by stress associated with an excessive crop load and not a pathological disorder. Fungal growth is a secondary, not a primary, factor in deterioration of shucks with decline.
`Mauritius' Lychee Fruit Development and Reduced Abscission after Treatment with the Auxin 2,4,5-TP
Authors: Stern R.A. , Kigel J. , Tomer E. , Gazit S.
Published: January 2019

Fruit development and abscission in `Mauritius' lychee (Litchi chinensis Sonn.) were studied over three consecutive seasons. Each season, two distinct abscission periods were observed. The first started at the end of full female bloom and continued for ≈ 4 weeks. Of the initial number of female flowers, 85 % to 90 % abscised during this period. The second period began after a lag period of≈ 1 week and lasted ≈ 2 weeks. About half of the remaining fruitlets abscised during this wave. AU of these fruitlets contained an embryo. The second wave coincided with a period of rapid embryo growth and endosperm loss. Tipimon (a commercial product containing the triethanolamine salt of the synthetic auxin 2,4,5-TP) consistently and significantly increased marketable fruit yield when applied between the two abscission periods. Chemical name used: 2,4,5 -trichlorophenoxy propionic acid (2,4,5 -TP).
Superficial Scald of `Granny Smith' Apples is Expressed as a Typical Chilling Injury
Authors: Watkins Christopher B. , Bramlage William J. , Cregoe Belinda A.
Published: January 2019

To examine the hypothesis that superficial scald of apple (Malus domestics Borkh.) is a chilling injury, `Granny Smith' apples were stored at temperatures ranging from 0 to 20C, temperature-conditioned before storage, and warmed during storage. Fruit stored at 0 or 4C developed supeficial scald. At 10C, surface defects occurred but they were not typical symptoms of scald, and at 15 or 20C no symptoms developed. Accumulation of α-1 faroesene and conjugated trienes in fruit peel correlated with increasing ethylene production, which was greater at higher temperatures. However, concentrations of conjugated trienes were highest at 0 and 4C. When fruit were kept at 10C for 5 or 10 days before storage, scald development after storage was not reduced. An interruption of 0C storage with a single warming period at 10 or 20C reduced scald development after 25 weeks of storage, maximum reduction occurring when fruit were warmed for 3 to 5 days at 20C after 1 to 4 weeks at 0C. Amelioration of scald declined as time at 0C before warming increased. Diphenylamine application after the same intervals at 0C, instead of warming, also was less beneficial as time before treatment increased. α-Farnesene and conjugated trienes increased during warming, but at the end of storage (when scald was developing) the conjugated triene concentrations in peel were reduced in fruit that had been warmed. Warming slightly increased yellowing, softening, and greasiness of fruit after storage, We conclude that chilling induced superficial scald on `Granny Smith' apples.
Sensitivity of Yield and Fruit Quality of French Prune to Water Deprivation at Different Fruit Growth Stages
Authors: Lampinen Bruce D. , Shackel Kenneth A. , Southwick Stephen M. , Olson Bill , Yeager James T. , Goldhamer Dave
Published: January 2019

The sensitivity of French prune (Prunus domestica L. syn. `Petite d'Agen') to water deprivation at various fruit growth stages was studied over 3 years in a drip-irrigated orchard. The soil was a poorly drained Rocklin fine sandy loam with a hardpan that varied from 4.75 to I m from the surface at the northern end of the orchard (shallow soil condition) to no hardpan apparent to 2 m below the surface at the southern end of the orchard (deep soil condition). Water deprivation during a) the first exponential phase of fruit growth or stage I, b) lag phase of fruit growth or stage II, c) first half of stage II, d) second half of stage II, e) second exponential fruit growth phase or stage III, and f) postharvest was compared to a fully watered control. Water deprivation caused the most severe reduction in tree water status when it was imposed over longer periods of time and during periods of high evaporative demand and also had mm-e severe effects under shallow soil conditions. Compared to the control treatment, deprivation during all of stage II (the most severe deprivation treatment) was associated with increased Ilowering, reduced fruit hydration ratio, and smaller fruit size under all soil conditions. Under deep soil conditions, deprivation during all of stage II resulted in increased return bloom, which was reflected in higher fruit loads and dry t-ha-' fruit yield. However, under shallow soil conditions, even though return bloom was increased with this treatment, fruit loads and dry t·ha-1 fruit yields were the lowest of all treatments. These differences in treatment effects in shallow vs. deep soil conditions were most likely the result of increased fruit drop, which occurred under shallow soil conditions as a result of rapid onset and increased severity ofstress. Treatments that had parallel effects in shallow and deep soil conditions resulted in statistically significant overall treatment effects, while those that had opposing effects in shallow vs. deep soil conditions did not show significant overall treatment effects. Substantial alternate hearing occurred, and, in general, dry fruit yields above ≈9 dry t·ha-1 resulted in a decrease in fruit load the following year, while loads below this value showed a subsequent increase. Based on a separate estimate of the theoretically stable value for each treatment, all deprivation treatments resulted in a higher sustainable fruit load compared to the fully irrigated control. This suggests that, for the purpose of prune fruit production, there may be an optimal level of tree water stress.
Methods for Measurement of Gas Volume of Fruits and Vegetables
Authors: Calbo Adonal Gimenez , Nery Amauri Alves
Published: January 2019

Theory is presented for a differential mass-volume technique to measure non-destructively gas volume (Vg) changes, based only on the initial and final masses and volumes of an organ. Volume was measured using Archimedes' principle, but a non-invasive image analysis procedure could be an improvement. A reduction in Vg during the ripening of `Kada' tomato (Lycopersicon esculentum Mill) fruits, and irreversible Vg changes of 0.02, 0.29, 0.66, 1.2, and 1.3 ml for mature-green fruits compressed by 0, 2.5, 5.0, 7.5. and 10 mm for 5 minutes indicates the potential of this procedure. The method was compared with other methodologies using sweetpotato (Ipomea batatas L.) root segments subjected to vacuum water infiltration. The results were similar to the pycnometric method. The gasometric method underestimated Vg for roots in which the intercellular air volumes where blocked by the water used for infiltration, and large overestimation occurred with the traditional infiltration technique without correction for water absorption. Absolute Vg values were also estimated by semi-pycnometry (defined as the difference between the organ volume measured by water immersion and the organ volume without Vg measured with a pycnometer, after its maceration and elimination of gas bubbles with vacuum). Semi-pycnometry applied to tomato and bell pepper (Capsicum annuum L.) fruits, where the use of tissue segments limits the pycnometric method, and in sweetpotatoes, where the gasometric method overestimates Vg, generated results that were consistently similar to the differential mass-volume method.
Measuring Incident Light on Grape Clusters Using Photosensitive Paper and Image Analysis
Authors: Price Steven F. , Schuette Marc L. , Tassie Elizabeth
Published: January 2019

Digital imaging and analysis was used to quantify and characterize the light exposure patterns of photosensitive paper tubes placed in representative cluster positions in two grape (Vitis vinifera L.) canopies: a minimally pruned and a vertically trained canopy. Blue pixel values of the captured images had a negative correlation with the log of irradiance from an integrating quantum sensor (r2 = 0.9308). The spectral response of the photosensitive paper was not measured. Histograms of incident light distribution on individual paper tubes were developed using imaging software. Histograms were able to quantify the distribution of incident light on individual tubes and were clearly related to the tube's exposure in the canopy. Average population curves of pixel light distribution of 20 tubes in each canopy were able to differentiate the typical cluster light environment in the two canopies. Tubes in the minimally pruned canopy had a larger proportion of their surface exposed to irradiances > 50 μmol·s-1·m-2 and 65% higher average irradiance than the vertical canopy. Image analysis of photosensitive paper appears to be a workable method to record the distribution ofincident light in plant canopies and may have utility in a range of ecological studies.
Identifying Olive Cultivars by Isozyme Analysis
Authors: Trujillo Isabel , Rallo Luis , Arús Pere
Published: January 2019

Pollen samples of 155 olive (Olea europaea L.) cultivars from different origins were analyzed to study isoenzymatic variability in five enzyme systems: alcohol dehydrogenase (ADH), esterase (EST), glucose phosphate isomerase (GPI), leucine aminopeptidase (LAP), and malic enzyme (ME) using starch gel electrophoresis. Polymorphism was observed in all of the isozyme systems. ME, GPI, EST, and LAP were the most useful systems for identification of cultivars. Different combinations of banding patterns of these systems allowed us to identify 85% of the cultivars. The remainder were separated into groups of two or three cultivars that could be identified using morphological characteristics. No intracultivar polymorphisms were observed.
Changes in Cuticular Compounds of Developing Pecan Leaves
Authors: Chortyk O.T. , Yates I.E. , Reilly C.C.
Published: January 2019

Leaf surface compounds of pecan [Carya illinoensis (Wangenh.) C. Koch] were analyzed with regard to developmental stage and to susceptibility to infection by Cladosporium caryigenum (Ell. et Lang. Gottwald). Immature and mature leaves of two resistant (`Elliott' and `Sumner') and two susceptible (`Wichita' and `Schley') cultivars were extracted with methylene chloride. Extracts were separated by silicic acid chromatography into polar and nonpolar fractions. Constituents of each fraction were subsequently separated by gas chromatography and were identified by gas chromatography-mass spectroscopy. Leaf surface constituents characterized included long-chain aliphatic hydrocarbons, aliphatic wax esters, triterpenoid constituents, aliphatic alcohols, fatty acids, and diacyl glycerides. The predominant surface compounds on immature leaves were lipids such as fatty acids, fatty alcohols, and glycerides. On mature leaves, lipids declined and aliphatic hydrocarbons and triterpenoids became predominant leaf surface constituents. The changes were observed for all cultivars, regardless of genotypic response to C. caryigenum. Thus, we conclude that cuticular chemicals change dramatically during leaf maturation but do not correlate with resistance to scab disease common to certain pecan cultivars.
St. Augustinegrass Rooting following Preemergence Herbicide Application
Authors: McCarty Lambert B. , Porter D. Wayne , Colvin Daniel L. , Shilling Donn G. , Hall David W.
Published: January 2019

Greenhouse studies were conducted at the Univ. of Florida to evaluate the effects of preemergence herbicides on St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] rooting. Metolachlor, atrazine, metolachlor + atrazine, isoxahen, pendimethalin, dithiopyr, and oxadiazon were applied to soil columns followed by placement of St. Augustinegrass sod on the treated soil. Root elongation and biomass were measured following application. Plants treated with dithiopyr and pendimethalin had no measurable root elongation and root biomass was severely (>70%) reduced at the study's conclusion (33 days). Root biomass was unaffected following isoxaben and oxadiazon treatments, but oxadiazon applied at 3.4 kg·ha-1 reduced root length by 50%. Atrazine at 2.2 kg·ha-1 and metolachlor + atrazine at 2.2 + 2.2 kg·ha-1, did not reduce root length in one study, while the remaining atrazine and metolachlor + atrazine treatments reduced cumulative root length and total root biomass 20% to 60%. Metolachlor at 2.2 kg·ha-1 reduced St. Augustinegrass root biomass by >70% in one of two studies. St. Augustinegrass root elongation rate was linear or quadratic in response to all treatments. However, the rate of root elongation was similar to the untreated control for plants treated with isoxaben or oxadiazon. Chemical names used: 6-chloro-N-ethyl-N'-(l-methylethyl)-1,3,5-triazine-2,4-diamine(atrazine);S,S-dimethyl2-(difluoromethyl)-4-(2-methylpropyl)-6-(t∼fluoromethyl)-3,5-pyridinecarbothioate (dithiopyr); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); 2-chloro-N-(2-ethyl- 6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).