bluuebunny/crossref_metadata_2025 huggingface dataset:
169 Root Characteristics of Peach Trees with Different Shoot Growth Habits
Authors: Tworkoski T.J. , Scorza R.
Published: February 2019

Peach trees (Prunus persica L.) with diverse shoot growth habits have been developed, but little is known about their root systems. Characterizing shoot and root systems can improve basic understanding of peach tree growth and be important in the development of rootstocks and own-rooted trees. This research determined shoot and root characteristics of four peach tree growth habits (compact, dwarf, pillar, and standard). Seed from four peach growth habits were planted in 128-L containers, grown outside during the 1998 growing season, and then harvested. Compact tree leaf number (1350/tree) was twice, but leaf area (6 cm2/leaf) was half, that of pillar and standard trees. The number of lateral branches in compact trees (34) was nearly three-times more than in pillar and standard trees. The leaf area index (LAI) of pillar trees was greater than compact and standard trees (13 compared with 4 and 3, respectively) due to a narrower crown diameter. Dwarf tree shoots were distinct with few leaves (134 per tree) and a large LAI of 76. Compact trees grew more higher-order lateral roots than pillar and standard trees. More second-order lateral (SOL) roots were produced by compact than standard trees (1.2 vs. 0.8 SOL roots/cm first-order lateral root). Pillar trees had higher shoot-to-root dry weight ratios (2.4) than compact and standard trees (1.7 for both) due to smaller root dry weights. The results indicate fundamental differences in root characteristics among the peach tree growth habits. Compact trees had more higher order lateral roots in roots originating near the root collar (i.e., more fibrous roots), and this correlated with more lateral branches in the canopy. Shoot weights were the same among pillar, compact, and standard trees but root weights were less in pillar trees, resulting in greater shoot-to-root dry weight ratios. These results indicate significant differences in root as well as shoot architecture among growth habits that can affect their use as scion or rootstock varieties.
170 The Effect of Ca: NH4 Ratio on the Growth of Sour Orange Seedlings
Authors: Swietlik Dariusz
Published: February 2019

The purpose of this study was to determine the effect of Ca: NH4 ratio in the rhizosphere of hydroponically grown sour orange seedlings (SO) (Citrus aurantium L.) on the plants' vegetative growth and N uptake. The experiment was prompted by our observation that application of N in the form of NH4 in conjunction with CaCl2 was more efficient in eliminating N deficiency in field-grown grapefruit trees than the same rates of N applied in the form of NH4NO3 without CaCl2. About 40-cm-tall SO were pruned back to the 4th leaf and grown for 6 weeks in nutrient solutions containing 5 mm NH4+ at CaCl2: NH4+ molar ratios of 1.0, 1.3, 1.6, 1.9, 2.2, or 2.5. In an additional treatment, NO3– was used as the sole source of N at CaCl2: NO3– ratio of 1:1. The level of Ca:NH4 ratio had no effect on new leaves number, shoot growth, total and average leaf area, specific leaf weight, as well as leaf, stem, and tap root dry weight. However, lateral root dry weigh decreased at Ca: NH4 ratio of 2.5. No growth differences were found when the plants were supplied with NH4+ vs. NO3– at Ca:N molar ratio of 1:1.
172 Calorimetric Evaluation of Apple Seed Dormancy
Authors: Carvajel-Millan E. , Gardea A.A. , Guerrero-P V. , Goycoolea F. , Rivera C.
Published: February 2019

Apple embryos from moist seeds kept at 4 °C were used for a calorimetric characterization of Red and Golden Delicious apple seed dormancy. Seeds were sampled at 100-h intervals during 1200 h. The metabolic response of such samples was compared to that from chilled Golden Delicious seeds (>1200 h) stored under controlled atmosphere (CA). Isothermal calorimetry at 25 °C, evaluated metabolic activity (q), respiration rate (RCO2), metabolic 65 °C estimated activation energy (Ea) in a 10 to 20 °C range, and respiration coefficients (Q10) from 10 to 50 °C at 10 °C intervals. Data showed a direct relationship between chilling exposure and embryo metabolic responses from both cultivars. Once chilling requirement was satisfied, Red and Golden Delicious seeds presented a significant increase (P ≤ 0.05) in q, 0.94 and 0.98 μW/mg dry weight (dw); RCO2, 9.9 and 7.6 mmol CO2/mg dw; and RSG·ΔHB, 3.6 and 2.5 μW/mg dw, respectively. On the other hand, q/RCO2 did not follow a definite pattern, neither in Red nor Golden Delicious cultivars. Ea decreased 19.2 and 23.4 J/mol per °K per mg dw in Red and Golden Delicious, respectively, as a function of seed chilling. Q10 showed a significant response to temperature, but not to chilling exposure. Golden Delcious seeds from CA showed a significant reduction on q, RCO2, and RSG·ΔHB of 0.28 μW/mg dw, 2.47 mmol CO2/mg dw, and 14 μW/mg dw, respectively. Results show that calorimetry is a sufficiently sensitive, fast, and precise tool to quantify metabolic responses during seed chilling, as evolving energy.
173 Calorimetric Evaluation of Metabolic Intensity of Apple Lateral Buds and Roots during the Transition from Para- to Endodormancy
Authors: Llamas J. , Gardea A.A. , Martinez-Tellez J.J. , Guerrero-P V. , Carvajal-Millan E. , Orozco J.A. , Rascon-Chu A.
Published: February 2019

Potted 1-year-old `Starking Spur' and `Golden Delicious' trees on MM.106 were used to characterize the metabolic changes in lateral buds and rrots during their transition from para- to endodormancy. Sampling period was from 4 Sept. to 25 Nov. 1999 at 10-day intervals. Well-formed lateral buds were collected from the apical section of current growth; while root samples were white rootlets. Isothermal calorimetry at 25 °C was used to evaluated metabolic activity (q), respiration rate (RCO2), metabolic efficiency (q/RCO2), and growth rate (RSG·ΔHB). In both cultivars, q from buds showed significant differences (P ≤ 0.05) among sampling dates; `Starking' rose from 1.8 to 3.7 μW/mg dry weight (dw), while in `Golden' change was from 2.1 to 3.3 μW/mg dw. RCO2, q/RCO2, and RSG·ΔHB showed a pattern similar to q. On each sampling date, cuttings were also forced to break and, in all dates, buds broke after 21 days, demonstrating a paradormant condition. MM.106 root tips q behave differently depending on the variety they were grafted on to. When grafted with `Starking', root tips produced a small, but significant, increase in q (from 9.1 to 15.7 μW/mg dw) as the season progressed. RCO2 and RSG·ΔHB behaved similarly, increasing from 27.6 to 57.6 mmol CO2/mg dw and 3.4 to 8.3 μW/mg dw, respectively. These conditions agreed with a dynamic root growth. A small decrease in q/RCO2 was observed. However, when grafted with `Golden' root tips metabolic responses did not increase; furthermore, q decreased while RCO2, q/RCO2, and RSG·ΔHB did not show a defined pattern. Four complete 2-year-old trees of each variety, kept in 1-m3 containers, were sampled. The relation of root/wood dry matter was estimated, with difference found between varieties.
180 Apogee™ Controls Shoot Growth and Fruit Parameters
Authors: Costa Guglielmo , Bregoli Anna Maria , Sabatini Emidio , Cristina Bomben , Giannina Vizzotto
Published: February 2019

The efficacy of Prohexadione-Ca on vegetative and reproductive parameters was tested for 3 years on three apple cultivars (Golden Delicious, Braeburn, and Fuji) at concentrations ranging from 125 up to 350 ppm. The Prohexadione-ca was applied after shoots reached 5 cm length, for 1 month. In all cases, Prohexadione-Ca reduced shoot growth, showed the tendency to increase fruit size and to enhance return bloom. In addition, it increased leaf coloration and higher chlorophyll content, and it induced higher photosynthetic efficiency than the control. The relationships among shoot reduction, chlorophyll content and photosynthetic efficiency are discussed.
182 Chemical Changes in the Cell Wall Composition of Calcium-infiltrated `Golden Delicious' Apples
Authors: Chardonnet C.O. , Sams C.E. , Conway W.S.
Published: February 2019

`Golden Delicious' apples (Malus ×domestica Borkh.) were pressure-infiltrated after harvest with 0%, 1%, 2%, 3%, or 4% CaCl2 solutions (w/v) and the chemical composition of the cell wall of the cortical tissue 2 to 4 mm under the epidermis was studied. The mineral composition of the control cell wall (0% CaCl2) was not affected by the pressure infiltration process. In addition, no significant change was noticed in cell wall associated protein, uronic acid, total polysaccharides, or non-cellulosic neutral sugar contents except for xylose and rhamnose, which decreased (-25%) and increased (+20%), respectively. When apples were infiltrated with CaCl2, Ca content of the cell wall increased and maximum accumulation was achieved with a 2% CaCl2 solution. Calcium infiltration also induced a two-fold increase in Na, a 27% decrease in P, and a 40% decrease in protein content. These data suggest that chemical changes occurring after Ca infiltration are not related to pressure infiltration alone, but are mainly due to the Ca accumulation in the cell wall after pressure infiltration of CaCl2 solutions. Saturation of the available binding sites for Ca occurred in the cell wall when fruit were infiltrated with 2% CaCl2, as no further significant changes in the cell wall chemical composition was detected in fruits infiltrated with 3% or 4% CaCl2.
184 Lovastatin Inhibits α-Farnesene Biosynthesis and Scald Development in `Delicious' and `Granny Smith' Apples and `d'Anjou' Pears
Authors: Ju Zhiguo , Curry Eric A.
Published: February 2019

Effects of Lovastatin treatment on ethylene production, α-farnesene biosynthesis, and scald development were studied using `Delicious' and `Granny Smith' apples and `d'Anjou' pears stored in air at 0 °C. During 6 months of storage, Lovastatin did not affect internal ethylene concentration, but reduced α-farnesene production in a concentration-dependent manner in both apples and pears. Lovastatin reduced scald at 0.63 mmol·L-1 and inhibited scald completely at 1.25 or 2.50 mmol·L-1 in `Delicious' and `Granny Smith' apples. In `d'Anjou' pears, Lovastatin at concentrations from 0.25 to 1.25 mmol·L-1 inhibited scald completely. After 8 months of storage, the inhibition of scald in both apples and pears by Lovastatin was concentration-dependent, but none of the concentrations eliminated scald. Compared with 11.8 mmol·L-1 diphenylamine (DPA), Lovastatin treatment reduced scald to the same level at 1.25 mmol·L-1 in `d'Anjou' pear and 2.50 mmol·L-1 in `Delicious' and `Granny Smith' apples. Compared to the controls, Lovastatin did not affect fruit color, firmness, soluble solid contents, or titratable acidity during storage in either apple or pear.
189 The Use of Hydrophobic Clay Films as a Barrier to Ice Nucleation in Plants
Authors: Wisniewski Michael , Glenn Michael , Fuller Mick
Published: February 2019

Most plants exhibit the ability to supercool to some extent without freezing. The extent of supercooling, however, is limited by the action of intrinsic and extrinsic ice nucleating agents which initiate ice formation and propagation within a plant at relatively warm subzero temperatures (-1.5 to -3.5 °C). In herbaceous plants, extrinsic ice-nucleating agents (such as ice-nucleation bacteria, dew, and other good nucleating agents) significantly limit the ability to supercool below 0 °C. It is believed that with an absence of these extrinsic nucleating agents that plants could supercool to less than -4 °C. Other evidence indicates that intrinsic nucleating agents may also significantly limit the extent of supercooling. Questions also exist about nucleation in woody plants and especially the new growth (flowers, leaves, and shoots) present in spring. A better understanding of how freezing is initiated in plants has been limited by the inability to determine and visualize the initial site of ice nucleation and pattern of ice propagation. We have used infrared video thermography to study freezing in young tomato (Lycopersicon esculentum) plants and to determine if a hydrophobic barrier on the plant surface could prevent the action of extrinsic nucleating agents such as Ice + bacterial strain (Cit7) of Pseudomonas syringae from initiating freezing within a plant. Tomato plants were grown in a greenhouse in individual pots and used when they were 4 to 6 weeks old. Freezing tests were conducted in a programmable freezing chamber, and freezing was visualized and recorded on videotape using an infrared radiometer. Freezing of the plants was extrinsically induced by the application of droplets (5 μl) of water containing Cit7. To provide a barrier to the action of extrinsic ice-nucleating agents, an emulsion of hydrophobic kaolin was applied to the plant surface before applying an extrinsic nucleating agent. Results indicate that dry, young tomato plants can supercool to as low as -6 °C whereas plants having a single droplet of Cit7 would freeze at -1.5 to -2.5 °C. Applying the hydrophobic barrier blocked the effect of Cit7 and allowed the plants to also supercool to -6 °C, despite the presence of frozen droplets. Experiments under natural freezing conditions are in progress.
191 Use of the Minolta SPAD-502 to Determine Chlorophyll Concentration in Ficus benjamina L. and Populus deltoides Marsh Leaf Tissue
Authors: Loh Felix , Grabosky Jason , Bassuk Nina
Published: February 2019

The Minolta SPAD meter has been used to evaluate chlorophyll concentration in plant material to provide an inexpensive method to collect rapid, nondestructive data. Correlations of SPAD data and chlorophyll concentrations in corn have been very accurate r2 = 0.95), and can be used to monitor plant nutrient status as a function of chlorophyll concentration. There has been evidence that the calibrated accuracy of the SPAD meter is diminished at low and high concentrations of chlorophyll. Our study attempted to build the same type of background information for two tree species for use in evaluating plant response in experimental media experiments. Ficus benjamina L. and Populus deltoides Marsh were grown in containers of varied media. Leaf tissue was measured with a Minolta SPAD-502, and the tissue was then removed and processed with N,N-dimenthylformamide for analysis in a spectrophotometer. The remainder of the leaf sample was analyzed in an ICAP for tissue nutrient levels. Data were analyzed to evaluate the usefulness of the SPAD meter for woody plant leaf tissue evaluation and to develop calibration curves for use in future studies. There was a positive correlation (r2 = 0.943 in Ficus) between SPAD data and combined concentrations of chlorophyll a and b. Accuracy of the SPAD data was diminished when chlorophyll concentrations were low (SPAD <20, chorophyll <450 μg·mL-1) and high (SPAD >45, chorophyll >1350 μg·mL-1)..
197 Effect of STC-4771, An Intermediate of ABA Synthesis, on the Anthocyanin Accumulation in Grapes
Authors: Lee W.S. , Lee J.C. , Hwang Y.S.
Published: February 2019

The coloration of grape berries depends on the anthocyanin synthesis during maturation. The quality of berries is often decreased due to the poor color development when berries are grown under unfavorable environments and/or inadequate internal factors are involved. It has been well-known that the level of ABA at ripening is closely associated with anthocyanin synthesis; thus, the external application of ABA results in the increase of anthocyanin content even in berries grown under favorable conditions. However, the agricultural use of natural ABA is not possible because of high prices. This experiment was conducted to study the potential of STC-4771 as a substitute for ABA. The effect of STC-4771 was studied in `Kyoho', `Pione', and `Delaware' grapes. Chemicals were applied when ≈10% of berries in a cluster were colored. In `Kyoho', anthocyanin synthesis was enhanced at a concentration of 100 mg/L and there was a trend in color enhancement in `Pione', regardless of treatment concentration, between 10 to 40 mg/L. However, no clear effect was found in `Delaware' at 50 to 100 mg/L. In an in vitro experiment, anthocyanin was only increased when an adequate amount of sucrose (0.6 m) was added in the incubation medium under light. Natural ABA effectively increased the anthocyanin content of berry segments even under shading condition through four bagging materials, but no effect was confirmed in STC treatment.
198 Possible Involvement of Polyamines in Floral Stimulus in Springbearing Strawberries
Authors: Zhang X. , Woods F.M. , Ebel R.C. , Himelrick D.G. , Singh N.K. , Mosjidis C.
Published: February 2019

A prevailing hypothesis indicates that a decrease in vegetative growth and cessation in floral initiation in strawberry in response to changes in photoperiod and temperature may correlate with hormonally induced changes. We investigated changes in endogenous free polyamines in crowns, flowers, leaves, and fruit of springbearing strawberries (Fragaria xananassa cvs. Chandler and Earliglow) in response to varying temperatures to induce flowering. Spermidine was the prominent free amine in crowns. No marked changes of putrescine, spermidine, and spermine were observed in crowns during the transition from vegetative to reproductive growth in either cultivar. In contrast, high levels of free polyamines were noted in young developing tissues such as the most recently initiated leaves, flower buds, and green fruit. When the putrescine synthesis inhibitor difluoromethylonithine (DFMO, 1 mm) was exogenously applied, levels of putrescine, spermidine, and spermine were altered in crown tissues in greenhouse experiments. These findings indicate that free polyamines may potentially be associated with the stimulation of new growth in springbearing strawberries under the present experimental conditions evaluated.
199 Training System and Photosynthetic Activity of `Perlette' Vines Grown in the Sonoran Desert
Authors: Orozco J. Antonio , Gardea A.A. , Valenzuela E. , Guerrero-P V. , Carvajal-Millan E.
Published: February 2019

Table grapes grown in the Sonoran Desert of Mexico are mostly an export commodity directed to early season markets. In order to define the effect on canopy management on light use and berry ripening, `Perlette' vines planted along eastwest rows (typical in such a region) were trained under four systems: slanted pergolas (SP), CIAD, lyre (LY), and T-trellis with open canopies (TTOC). They were compared with traditional closed-canopy T-trellis (TT). Variables evaluated were photosynthetic active radiation (PAR), photosynthesis (PH), stomatal resistance (SR), chlorophyll content (CC), and berry total soluble solids (TSS). At harvest, PAR values for LY, SP, CIAD, TTOD, and TT were 2192, 2076, 1900, 885, and 771 μmol·m-2·s-1, respectively. In the same order, PH at veraison was 12.5, 12.7, 11.0, 10.5, and 5.1 μmol CO2/m2 per s, while in recently harvest vines it decreased to 9, 9, 8.1, 5.1, and 3.7 μmol CO2/m2 per s. SR at veraison was 3.4, 2.6, 2.8, 3.9, and 4.2 s/cm, but, after harvest it was 2.5, 3.5, 2.3, .2.9, and 6.8 s/cm. No significant differences in CC were found among treatments. TSS on 27 Apr. reached 14.9, 15.3, 15.7, 14.5, and 12.2 °Brix; on 29 Apr. they increased to 15.9, 15.5, 16.3, 15.1, and 13.1 °Brix. Based on the above, we demonstrated that canopy management and sunlight cropping represent a useful tool to advance table grape ripening, thus allowing an early harvest and therefore access to the high prices typical of early season markets.
202 Elongation of Asparagus Spears Throughout a Spring Harvest
Authors: Krarup Christian , Contreras Samuel
Published: February 2019

Daily and total elongation of spears, plus elongation rates, and the number of days to reach maximum height of spears prior to branching were measured on 5-year-old asparagus plants of cultivars Atlas, Ciprés, Gijnlim, Jersey Giant, JWC1, UC-157 F1, and UC-157 F2. Six measurement periods were carried out every other week during a spring harvest, measuring spears from emergence to maximum height before branching (5 mm of branch above budscale).Daily elongation varied widely through harvest, from less than 1 cm/day when average temperatures were below 10 °C, to more than 14 cm when daily temperatures reached a mean between 16 to 18 °C. Total spear length varied from an average of 50 cm, at the beginning of spring, to an average of 32 cm at the end of spring. Elongation rates varied between and within periods: less than 1cm/day at the beginning of the season to more than 15 cm/day at the end of the season; within a given period lower rates prevail at start of elongation. Days to reach maximum height varied from up to 13 days, at the beginning of the season, to 5 days at the end of the harvesting period. Cultivars showed somewhat similar elongation patterns; however, variations observed could have significant effects on quality and total commercial yield of spears.
203 Influence of Irrigation Levels and Application Moments on Growth and Performance of an Early Sweetpotato Cultivar
Authors: Gilsanz J.C. , Duran M. , Maiques R. , Bascans F. , Garcia C.
Published: February 2019

The objective of this work was to establish the dry-matter production and yield at different irrigation levels and moments of water application. An early cultivar, INIA-Sandu, was transplanted in Nov. 1996. Treatments were a combination of: no irrigation, irrigation at 25 kPa and 75 kPa of soil moisture tension during the first 60, 30 to 90, 60 to 120 days, and during all the cycle after crop establishment. Sequential samples were done throughout the growth cycle. The parameters evaluated were fresh and dry weight of leaves, stems, and roots. At the end of the crop cycle, yield was determined. Irrigation levels and early applications affected weight of leaves, stems, and roots. Yield was greater at early water applications during the growth cycle. Lower soil moisture tensions tend to have greater yields.
204 Scarification and Moisture Effects on Triploid Watermelon Seed Germination
Authors: Grange S. , Leskovar D.I. , Pike L. , Cobb G.
Published: February 2019

Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the U.S. However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of the H2O or H2O2; both nicking and H2O2 increased germination, but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (CV = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seedcoat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
206 Growth, Gas Exchange, and Water Relations of Micropropagated Chile Ancho Pepper (Capsicum annuum L. cv. San Luis) Plantlets during Acclimatization and Post-acclimatization
Authors: Estrada-Luna Andres A. , Davies Fred T. , Egilla Jonathan N.
Published: February 2019

Micropropagated chile ancho pepper (Capsicum annuum L. cv. San Luis) plants were transferred to ex vitro conditions to study plantlet performance and selected physiological changes that occur during acclimatization and post-acclimatization. The physiology of the plantlets was characterized by measuring leaf gas exchange and water status. Plant growth was determined by assessing plant height, leaf number, total leaf area, relative growth rate (RGR), and leaf, root, and stem dry mass. Measurements were taken at 0, 1, 2, 3, 6, 12, and 24 days after transplanting. After initial transplanting ex vitro to liner pots with soilless media, plantlet wilting was observed that correlated with reduced leaf relative water content (RWC). Water stress was partially alleviated by a reduction in stomatal conductance (gs), confirming that the in vitro formed stomata were functional and able to regulate transpiration (E) to minimize desiccation losses. Because of this stomatal control, plantlets had minimal transplant shock, recovered, and survived. Prior to transplanting, micropropagated plantlets showed heterotrophic/mixotrophic characteristics as indicated by low photosynthesis [(A) 4.74 μmol·m2·s-1]. During acclimatization, RWC, gs, E, and A were significantly lower 2 days after transplanting. However, within 6 days after transplanting, plantlets recovered and became autotrophic, attaining high A (16.3 μmol·m-2·s-1), gs, and E. The stabilization and improvement of plantlet water status and gas exchange during acclimatization and post-acclimatization closely correlated with dramatic increases in plantlet growth.
210 Effects of Salt and Water Stress on the Growth and Photosynthesis Rate of Bell Pepper (Capsicum annuum L.)
Authors: Larrinaga-Mayoral J.A. , Troyo-Dieguez E. , Toyota M. , Murillo-Amador B.
Published: February 2019

Salt and water stress affect in a significant way most common horticultural crops in northwest Mexico, where bell pepper, hot pepper, and tomato are the most important vegetable crops. Growth rate (GR) and physiological traits in bell pepper were analyzed under salt and drought stress. Two cultivars of bell pepper, `Hungarian Yellow' (HY) and `Sta. Fe Grande' (SG), were evaluated. GR in both cultivars was decreased by salt and drought stress interaction. Salt concentration in the irrigation water affected the amount of dry matter in the plant tissue. Relative growth ratio (RGR), net assimilation ratio (NAR), leaf area ratio (LAR), and photosynthesis rate (Pn) decreased in a correlated amount to the salt NaCl content in the experiment (0, 80, and 160 mm). Differences in the RGR under salt and drought stress between SG and HY were significant. The observed decrease in RGR was explained by NAR and LAR, where RGR was more affected by NAR than LAR. Similarly, the decrease in NAR was explained by C/F and Pn, indicating that NAR was more affected by Pn than C/F. The difference in observed NAR between both cultivars was understood by difference in C/F. Finally, a high relation of C/F in SG cultivar under salt and drought stress was caused by a physiological use of photosynthetic products, causing a significant decrease in NAR in the cultivar HY. This difference in NAR was found to be the factor that affected RGR in both cultivars.
216 Carbohydrate and Alliin Concentrations in Garlic Produced under Different N Fertilzation and Irrigation Regimes
Authors: Cantwell M. , Hong G. , Voss R. , May D. , Hanson B.
Published: February 2019

Garlic (cv California Late) was produced under four irrigation regimes (110% and 130% evapotranspiration with two water cut-off dates, 10 and 24 May 1999) in combination with three nitrogen fertilization levels (100, 250, and 400 lb total N). Bulbs were manually harvested mid-June, cured 3 weeks shaded at ambient temperatures and the outer whorl of cloves manually peeled. Samples were freeze-dried, and carbohydrate (fructan and free sugars) and alliin (substrate for alliinase activity and indicator of potential pungency) concentrations were determined by HPLC. The percent dry weight was not affected by the irrigation treatment, but was reduced with increased N rate (41.3% to 39.0%). Alliin concentrations varied from 8.3 to 13.8 mg/g DW for 110% and 130% Eto irrigation treatments. Alliin concentrations were not affected by N fertilization (average = 11.5 mg/g DW). Fructan concentrations were affected by N fertilization treatment, with the highest content (802 mg/g DW) associated with the lowest N level, and the lowest (717 mg/g DW) content in samples from the highest N rate. Sucrose concentrations increased with increased N, but glucose and fructose concentrations did not vary with N fertilization. Fructan as percent of total carbohydrate remained constant across irrigation treatments (96.6% + 0.2%) and across N fertilization treatments (96.6% + 0.3%).
222 Energy Balance of Six Common Landscape Surfaces
Authors: Montague Thayne , Kjelgren Roger , Rupp Larry
Published: February 2019

Growth of woody landscape plants is strongly affected by the underlying surface. In urban areas, plants are subjected to energy balance characteristics of a variety of surfaces. This research investigated energy balance properties of six common urban surfaces: Kentucky bluegrass, pine bark mulch, concrete, asphalt, lava rock mulch, and gravel rock mulch. Each summer over a 2-year period incoming global radiation (GW), relative humidity, and air temperature were measured over each surface, and surface reflectivity (AW), surface temperature (TS), soil temperature (TO), and soil heat flux (SF) were measured below each surface. Thermal conductivity (K) and emitted surface longwave radiation (LW) were also calculated. Surface property differences were determined by regression analysis. Incoming global radiation (independent variable) versus TS, TO, SF, LW data (dependent variable) were analyzed. Linear or quadratic curves were selected according to significance of each variable and the coefficient of determination (R2). Surface reflectivity was greatest for concrete and least for lava rock mulch, and K was greatest for asphalt and concrete and least for lava rock and pine bark mulch. Under maximum GW, regression data indicate that SF and TO would be greatest under asphalt and least under lava rock and pine bark mulch. Under similar circumstances, TS and LW would be greatest for pine bark mulch and least for Kentucky bluegrass. This research revealed that more energy was conducted into the soil below asphalt and concrete, and that a greater portion of GW was prevented from entering the soil below pine bark and lava rock mulch than below other surfaces. Due to these effects, and the lack of evaporative cooling, surface temperatures were greater, and more longwave radiation was emitted from, non-vegetative surfaces than from turf.
224 Influece of Early Harvest PGR on the Growth of Five Ornamental Species
Authors: Ruter John M.
Published: February 2019

Decline of certain container-grown ornamental species during the hottest months of summer is a common problem for nurserymen in the southeastern United States. When roots are killed due to high root-zone temperatures and growth ceases, production of plant hormones also decreases. A study was conducted with Early Harvest PGR (Griffin LLC, Valdosta, Ga.), which contains cytokinins, gibberellic acid, and indole butyric acid, to determine if this product would improve the growth of five ornamental species that typically decline during the summer in south Georgia nurseries. The species used were Cotoneaster dammeri Schneid. `Coral Beauty', Cotoneaster salicifolius Franch. `Green Carpet', Spiraea japonica L. `Shirobana', Thuja occidentalis L. `Little Giant', and Weigela florida (Bunge) A. DC. `Minuet'. The treatments (control, 1.5 and 3.0 mL Early Harvest PGR/1125 mL water) were applied every 2 weeks from mid-June until mid-Sept. 1999 as a foliar drench. Treatment of both Cotoneaster species and the Thuja with Early Harvest PGR resulted in little influence on plant growth. While growth indices did not increase, shoot dry mass of Spiraea and Weigela increased 17% and 26%, respectively, when treated with Early Harvest PGR at the medium rate. Plant quality ratings for Spiraea increased when the 1.5-mL rate of Early Harvest PGR was applied. A rate of 3.0 mL of Early Harvest PGR on Spiraea decreased shoot and root dry mass, total biomass, root ratings, and final plant quality. Root ratings and plant quality were highest for Weigela grown with the 1.5-mL Early Harvest PGR treatment. These results indicate that treatment of woody ornamentals with Early Harvest PGR for positive results is both species- and rate-dependent.
228 Considerations for the Nursery Production of the Ornamental Grass Hakonechloa macra `Aureola'
Authors: Harvey Michael P. , Brand Mark H.
Published: February 2019

Studies conducted in 1998 and 1999 analyzed the influence of division size, nutrition, and potting medium pH on the growth rate of Hakonechloa macra `Aureola' in nursery-container production. For each study, divisions were made from container-grown nursery stock in late March, then established in 325-mL pots in a greenhouse prior to being transplanted to 3.7-L nursery containers in late May. Grass plants were grown outdoors, under 30% shade density cloth, with drip irrigation from June through September, and, excluding plants in the nutrition study, received top-dressed 17-6-10 slow-release fertilizer containing micronutrients. To determine the optimum division size for production, divisions of four sizes were made (based on one to two, four to six, eight to 10, or 12 to 15 buds per plant). There was a significant division size effect on bud count, leaf area, plant weight, width, and shoot count only when comparing the two lowest division sizes with the two highest. Treatment effects were insignificant among divisions containing one to two and four to six buds, or between eight to 10 and 12-15 buds. Both the larger two sizes produced marketable plants; therefore, divisions with eight to 10 buds are recommended for a schedule aimed at producing salable Hakonechloa over one growing season. The smallest division class is believed to be the more efficient size when one merely wishes to increase plant stock. In a separate study, a factorial trial testing ppm fertilizer (28, 56, 112, 224, and 448 ppm N) and N-P-K formulation (1-1-1, 2-1-2 and 4-1-4) did not generate significant differences between formulations. Plants were fertigated once a week, and EC levels were monitored bi-weekly from leachate collected in drainage saucers. Plant responses to N rates suggest that electrical conductivity levels be kept around 2.5 mS·cm-1 from a 112 ppm N fertilizer (EC can go as high as 4.0 mS·cm-1 with 224 ppm N). It was evident H. macra `Aureola' prefers acidic soil in production. When lime was not included in the potting mixture (a control treatment equating to a pH of about 4.5), leaf area, bud count, and shoot number doubled relative to the three lime treatments (2, 6, and 16 g lime/L of media, or 3.4, 10.1, and 26.9 lb/yard3).
229 Influence of Diploid Pollinizers on Seedless Watermelon Yield and Quality
Authors: Fiacchino Dena C. , Walters S. Alan
Published: February 2019

Due to the lack of viable pollen produced in seedless (triploid) watermelons, fruit set in seedless watermelons requires a standard seed (diploid) producing cultivar (hereafter referred to as a pollinizer) to be interplanted as a source of pollen. It is recommended that one row of pollinizer be planted for every two rows of seedless watermelon. There is little to no information available to growers comparing the effects of pollinizers on seedless watermelon yield and quality. We conducted a study to evaluate the effectiveness of three seeded pollinizers (`Crimson Sweet', `Fiesta', and `Royal Sweet') on yield and quality of four seedless watermelon hybrids (`Abbott and Cobb 5244', `Crimson Trio', `Millionaire', and `Tri-X 313'). `Royal Sweet' as a pollinizer tended to produce higher yields of small (<3.6 kg) and medium-sized seedless watermelons (3.6-7.3 kg) per acre compared to `Crimson Sweet' and `Fiesta'. `Crimson Sweet' produced a greater number of large (>7.3 kg) seedless watermelons compared to `Fiesta' and `Royal Sweet'. However, the number of marketable melons (>3.6 kg) did not differ among the three pollinizers evaluated. Two quality measurements taken (hollow heart and soluble sugars) were not influenced by the choice of pollinizer.
231 Pollinizer Frequency for Optimum Fruit Production of Triploid Watermelons
Authors: NeSmith D. Scott , Duval John R.
Published: February 2019

During 1998 and 1999, `Genesis' triploid watermelons were grown in large blocks with a single row of the diploid `Ferarri' planted as a pollinizer in the middle. A once-over harvest of triploid watermelons was made each year in harvest lanes 0-, 1.5-, 3.0-, 4.5-, 6.0-, 7.5-, and 9.0-m perpendicular distances from the pollinizer row. Individual fruit were weighed and counted. Data from both years indicated a similar distribution of triploid fruit with respect to distance from the pollinizer row. The greatest number of triploid fruit per unit land area was in the harvest row 3.0 m from the pollinizer row. When distance from the pollinizer row was 6.0 m or greater, triploid fruit numbers diminished substantially. Yield estimations made each year using the fruit density data suggested that a 1 pollinizer: 4 triploid ratio gave the maximum total triploid fruit yield per hectare for 1.5-m row spacings. These results should prove useful in designing field planting strategies that seek to optimize triploid watermelon production.
232 Inverse Day/Night Temperature Influences Yield and Canopy Height of Hydroponically Grown Sweetpotato
Authors: Mortley D.G. , Hill J.H. , Bonsi C.K. , Hill W.A. , Morris C.E.
Published: February 2019

Growth chamber studies were conducted to determine if inverse day/night temperature could control canopy height of sweetpotato without adversely affecting storage root yield. Four 15-cm-long vine cuttings of TU-82-155 sweetpotato were grown in rectangular nutrient film technique hydroponic troughs for 120 days. Two troughs were placed into each of six reach-in growth chambers and subjected to 24/18, 26/20, 28/22, 18/24, 20/26, and 22/28 °C, respectively. Growth chamber conditions included a 12/12-h photoperiod, 70% RH, and photosynthetic photon flux of 1000 μmol·m-2·s-1 at canopy level. Total and edible storage root yields were reduced by 50% among plants grown under cool days/warm nights regimes. Harvest index was similar among treatments except for the low value obtained at 22/28 °C. Canopy height was positively correlated with the change in temperature, and for every 2 °C decrease there was a 3.1 centimeter decrease in canopy height. Inverse day/night temperature effectively controlled canopy height but at the expense of storage root production.
233 Alteration of Flower Development and Fruit Growth in Summer Squash
Authors: Wyatt Jim E.
Published: February 2019

Many summer squash hybrids initiate flowering by first producing one or more pistillate flowers before the development of any staminate flowers. These first pistillate flowers have no pollen source unless an earlier squash planting is nearby. The objectives of this study were to measure the loss in yield incurred by the absence of pollination and to determine if sex expression in squash could be altered by use of gibberellic acid (GA). `Cougar' summer squash was planted in 12 isolated plots on 13 May; four plots had adjacent rows planted on 3 May to provide pollen for the earliest developing pistillate flowers in those plots. On 28 May, 0.146 L·ha-1 of GA (ProGibb 4®) was applied to an adjacent row in four of the plots planted on 13 May. The four control plots received no treatment. At anthesis, pistillate and staminate flowers were counted daily for 10 days. The first six pistillate flowers that bloomed in each plot were identified and measured (length and diameter) on the day of anthesis, and at 4 and 7 days after anthesis. Fruit were harvested five times at 2-day intervals and data are reported on fruit ≤5.7 cm in diameter. GA had no effect on squash flowering habit. At 4 and 7 days after anthesis, fruit were smaller in plots where no pollen source was available. Early yields were higher for the first two harvests in plots where pollinators were present. A small, early planting of squash should be made to provide staminate flowers for normal growth and development of early fruit on the main summer squash crop.
236 Heirloom Tomato Cultivar Evaluation
Authors: Grassbaugh Elaine M. , Bennett Mark A. , Harker Thom , Schmittgen Mark
Published: February 2019

The specialty vegetable market is a rapidly expanding niche in the produce industry. One popular sector of this market is focused on heirloom tomatoes. Heirloom varieties, mostly open-pollinated, are often favored for their taste and unique shapes and colors. Older, traditional varieties have been maintained mostly by home gardeners, seed saver organizations, and government germplasm centers, but are becoming increasingly popular with commercial growers, consumers, and seed companies. Special growing techniques and attention to postharvest handling is also necessary with heirloom tomatoes because most do not have an extended shelf life. For growers willing to develop special harvesting and handling techniques, specialty tomatoes offer colors, shapes, and flavors that are an important part of today's cuisine. Performance of a given cultivar will vary from year to year depending on several factors: planting date, irrigation, disease pressure, staking practices, and climatic conditions during the growing season. Fourteen heirloom tomato cultivars have been researched at Ohio State Univ. (OSU) since 1995. Data collected on yield, fruit characteristics, market outlets, cultural information, special harvesting and handling requirements, and disease pressure for heirloom cultivars will be presented.
238 Seed Size Effects on Brassica Transplant Production
Authors: Nascimento Warley M.
Published: February 2019

The growing of transplants in plug cell trays is the primary method of producing brassica transplants in many countries. Seed quality is an important aspect to achieve success in transplant production. Seed size may affect seed performance, seedling growth and development of brassica transplants. Seeds of cauliflower (`Vitoria de vero') and cabbage (`Unio') from Embrapa Vegetables were used in this study. During seed conditioning, seeds were classified using round screens generating three (>1.5, 1.5-2.0, and 2.0-2.5 mm) and four (>1.5, 1.5-2.0, 2.0-2.5, and < 2.5 mm) seed size categories, for cauliflower and cabbage, respectively. The original seed lot was used as control. Seed weight increased with seed size. Seed germination (laboratory) and seedling emergence (greenhouse) were not affected by seed size. In both species, root and shoot weight, and leaf area, measured 30 days after seeding, in greenhouse conditions, increased with seed size. Also, transplants from larger seed size resulted in a significantly higher root weight, shoot weight, and leaf area relative to the original (control) seeds. The results indicate that, overall, an adequate seed conditioning improve brassica transplant quality.
239 Seed Germination and Seedling Characteristics of Cucurbits as Affected by Dry Heat Treatment and Subsequent Handling
Authors: Bang Hae-Jeen , Hwang Soo-Jung , Ham Hyun-Sook , Lee Jung-Myung
Published: February 2019

Dry heat treatment has been commonly used to inactivate some seed-borne pathogens in vegetable seeds. Virtually all the gourd seeds for watermelon rootstock are being treated with dry heat to inactivate cucumber green mottle mosaic virus (CGMMV, a strain of tobamovirus) and Fusarium. Seeds of five gourd and one squash cultivars were treated with dry heat (35 °C for 24 h + 50 °C for 24 h + 75 °C for 72 h) and, immediately after the dry heat treatment, the seeds (moisture content of 1% or lower) were allowed to absorb atmospheric moisture in a moisture saturated chamber until the seed moisture contents reached 2% to 8%. After the equilibrium obtained, the seeds were sealed in air-tight bags and stored for 1 day or 30 days at 20 °C. The seeds were then sown in cell trays and the emergence and seedling characteristics were evaluated. Dry heat treatment caused significant delay in emergence in all tested cultivars, but had little or no influence on the final emergence rate. Moderate to severe injury was observed in seedlings grown from dry heat-treated seeds in three out of six cultivars tested. However, little or no dry heat phytotoxicity was observed in other cultivars, thus suggesting the marked differences in cultivar susceptibility to dry heat treatment. Rapid humidification before sealing also appeared to reduce the early emergence rate in some cultivars, but had no effect on the final emergence rate in most cultivars. Storage of dry heat-treated seeds in sealed bags for 30 days before sowing was highly effective in minimizing the phytotoxicity symptoms in seedlings as compared to the seedlings grown from the seeds sown immediately after the dry heat treatment. This suggests that the reestablishment of metabolic process required for normal seed germination requires a long period after the dry heat treatment. Other characteristics associated with DH treatment will also be presented.
241 Effect of Scion-Rootstock Combinations on Premature Fruit Drop in Mango
Authors: Predner D. , Cedeno-Maldonado A.
Published: February 2019

Studies were conducted to determine the effect of scion-rootstock combinations on premature fruit drop. Ten-year-old trees of the varieties Parvin and Tommy Atkins grafted on Eldon, Malda, Colombo Kidney, Julie, and Cuban were used. The number of prematurely dropped fruits was counted weekly for 8 consecutive weeks after flowering. A smaller fruit drop index was observed when `Parvin' was grafted on Malda, Julie, and Cuban than when grafted on Colombo Kidney. There was no significant difference in fruit drop index between Eldon and Colombo Kidney. Fruit drop index was greater in `Parvin' than in `Tommy Atkins'.
243 Manipulation of Peach Tree Growth and Development Using Graft-transmissible Agents
Authors: Gibson Philip G. , Reighard Gregory L. , Scott Simon W. , Ouellette David R.
Published: February 2019

Delaying bloom to reduce spring frost risk and reducing labor costs by increasing orchard efficiency are important goals of peach producers. At the Musser Fruit Research Center near Clemson, S.C., `Coronet' peach trees were inoculated with Peach Latent Mosaic Viroid (PLMVd) to induce bloom delay and reduce shoot vigor. Trees were grown in a high-density, Y-trained orchard system to determine the potential benefit of reduced shoot vigor on labor efficiency in summer pruning operations. In Aug. 1997, `Ta Tao 5' buds were grafted onto the scaffolds of 2-year-old `Coronet' peach trees to transmit PLMVd. Transmission was confirmed by dot-blot on N+ nylon membranes using cRNA probes. Bloom was not delayed in the following year, Spring 1998, but bloom was delayed 7 days in Spring 1999. Yields were unaffected in 1998, but the total fruit weight produced on PLMVd-treated trees was significantly less in the 1999 harvest. Individual fruit weight, firmness, and color were improved on the treated trees. Shoot vigor was reduced on the PLMVd treated trees in the summers of 1998 and 1999, resulting in a significant reduction in pruning time and pruning weights. Light penetration was significantly increased in the treated trees when compared to the untreated controls in the summers of 1998 and 1999. Fruiting shoot length and the number of fruit per shoot was unaffected by the PLMVd presence. The trunk cross-sectional area was significantly less on the treated trees when compared to the untreated controls after each year of growth. Autumn defoliation occurred earlier on the treated trees in Fall 1998 and Fall 1999. The manipulation of peach tree growth and development was accomplished using graft transmissible agents as PLMVd induced several beneficial growth and developmental modifications in established peach trees.