bluuebunny/crossref_metadata_2025 huggingface dataset:
Crop Coefficients Specific to Multiple Phenological Stages for Evapotranspiration-based Irrigation Management of Onion and Spinach
Authors: Piccinni Giovanni , Ko Jonghan , Marek Thomas , Leskovar Daniel I.
Published: February 2019

Weighing lysimeters are used to measure crop water use during the growing season. By relating the water use of a specific crop to a well-watered reference crop such as grass, crop coefficients (KC) can be developed to assist in predicting crop needs using meteorological data available from weather stations. This research was conducted to determine growth stage-specific KC and crop water use for onions (Allium cepa L.) and spinach (Spinacia oleracea L.) grown under south Texas conditions. Seven lysimeters, consisting of undisturbed 1.5 × 2.0 × 2.2-m deep soil monoliths, comprise the Texas AgriLife Research–Uvalde lysimeter facility. Six lysimeters, weighing ≈14 Mg, have been placed each in the middle of a 1-ha field beneath a linear low-energy precision application irrigation system. A seventh lysimeter was established to measure reference grass reference evapotranspiration. Daily water use for onion and spinach was measured at 5-min intervals. Crop water requirements, KC determination, and comparison with existing Food and Agricultural Organization (FAO) KC values were determined over a 2-year period for each crop. The KC values determined over the growing seasons varied from 0.2 to 1.3 for onion and 0.2 to 1.5 for spinach with some of the values in agreement with those from FAO. It is assumed that the application of growth stage-specific KC will assist in irrigation management and provide precise water applications for a region of interest.
Lettuce Response to Phosphorus Fertilization with Struvite Recovered from Municipal Wastewater
Authors: González-Ponce Ricardo , López-de-Sá Esther G. , Plaza César
Published: February 2019

Struvite (MgNH4PO4·6H2O) production is widely studied as a way to remove phosphorus (P) from wastewater and generate a potentially marketable P fertilizer, but its effects on crops have yet to be researched more thoroughly. This study was conducted to evaluate struvite recovered by the Spanish Research Council (CSIC) pilot process (STR) as a source of P for lettuce (Lactuca sativa L.) by comparing its effectiveness with that of single superphosphate (SUP), a common P fertilizer derived from phosphate rock. In a greenhouse pot experiment, a P-deficient loamy sand soil was amended with either SUP or STR at P rates of 0, 4, 8, 12, 16, and 20 mg·kg−1. Nitrogen and potassium were uniformly supplied to all treatments. The response of lettuce head fresh weight and P uptake to P rate exhibited statistically significant quadratic relationships for both SUP and STR. With respect to SUP, STR was significantly more effective in increasing lettuce yield and P uptake, probably because of the larger amount of magnesium (Mg) incorporated with this material and a synergistic effect on P uptake. This work supports previous findings based on other test crops in suggesting that STR can be a P source attractive to the fertilizer market with additional agronomic and environmental benefits such as providing available Mg and nitrogen, helping attenuate consumption of phosphate rock, and reducing release of P by discharge of treated wastewaters to surface and groundwater systems.
Phosphate Sorption of Calcined Materials Used as Components of Soilless Root Media Characterized in Laboratory Studies
Authors: Ogutu Rose A. , Williams Kimberly A. , Pierzynski Gary M.
Published: February 2019

Calcined materials may contribute enhanced phosphate (PO4-P) retention to soilless root media used in container production. Properties of nutrient retention vary greatly depending on the parent clay and calcining treatment. This research characterized PO4-P sorption of various calcined clay products, including low and regular volatile material (LVM and RVM) 2:1 attapulgite, montmorillonite, and illite clays at various particle sizes; 1:1 kaolin clays in powder form; and diatomaceous earth. Extractable PO4-P, initial pH, PO4-P sorption isotherms, amount of P sorbed as a function of solution pH at a fixed total concentration, and degree of phosphorus saturation were determined. Initial pH of the clays ranged from 3.7 to 8.7. Sorption isotherms were conducted with initial adsorbate concentrations ranging from 0 to 200 mg·L−1 PO4-P from KH2PO4. The calcined materials varied in their ability to sorb PO4-P and generally yielded L-type isotherms, indicating that the adsorbate had relatively high affinity for the calcined material sample surface at low surface coverage. Some 2:1 calcined clays exhibited substantial PO4-P retention, but 1:1 calcined clays and diatomaceous earth did not. Clays with less moisture (LVM) resulted in greater PO4-P sorption than those calcined at lower temperatures (RVM). Terra Green montmorillonites had higher PO4-P sorption than Terra Green attapulgites. Laboratory results indicated potential for substantive PO4-P retention by several of the calcined clay materials when used in container production. For most materials, PO4-P sorption did not show pronounced pH dependence, which suggests that PO4-P retention is not influenced by pH-dependent charge within the pH range of container production.
Selenization of Basil and Cilantro Through Foliar Applications of Selenate-selenium and Selenite-selenium
Authors: Kopsell Dean A. , Sams Carl E. , Barickman T. Casey , Deyton Dennis E. , Kopsell David E.
Published: February 2019

Selenium (Se) is an essential mammalian micronutrient. Adult humans have a daily requirement of 55 to 70 μg/day Se depending on sex and pregnancy/lactation for females. In addition, recent studies have shown health benefits with dietary Se supplementation of 100 to 200 μg/day Se. However, daily intakes in humans greater than 900 μg Se will result in toxicity called selenosis. Although not essential in plant nutrition, some species can bioaccumulate Se. Brassica and Allium species became prime candidates for Se enrichment because of their ability to accumulate and tolerate high concentrations of Se in edible tissues; however, there is now concern that these species are too efficient at selenization and overconsumption of their selenized tissues could result in selenosis. Herbal crop species are consumed regularly in the diet for their culinary flavor attributes. Basil (Ocimum basilicum L.) and cilantro (Coridandrum sativum L.) are not classified as Se accumulators. Therefore, a study was undertaken to determine the potential to selenize basil and cilantro through foliar Se applications to consistently supplement diets with nutritionally beneficial levels of Se. Plants of each species were grown in both growth chamber and field environments and treated with foliar applications (5 mL per plant) of selenate-Se and selenite-Se at concentrations of 0, 2, 4, 8, 16, and 32 mg·L−1 Se. Crops received three separate foliar applications at ≈5-day intervals beginning 24 to 28 days after planting for the growth chamber plants and 50 days after planning for the field environment. Selenium accumulation in both basil and cilantro leaf tissues increased linearly under both selenate-Se (P ≤ 0.001) and selenite-Se (P ≤ 0.001) foliar treatments in growth chamber and field evaluations. Maximum Se leaf tissue concentrations for basil and cilantro ranged from 13 to 55 μg·g−1 Se dry weight. Selenization of basil and cilantro is possible through foliar Se applications, and Se fortification of herbal crops may provide alternative delivery systems in human diets.
Empirical Models of Potassium Uptake by Dieffenbachia amoena ‘Tropic Snow’ Under Different Nitrogen Sources
Authors: Becker Silvia Jiménez , Plaza Blanca María , Lao María Teresa
Published: February 2019

Nutritional solution composition in fertigation must be designed according to crop needs. These needs are variable and depend on factors like plant growth rate, environmental conditions, and water uptake. The objective of this work is to study the influence of the N-form supply (N-NO3– or N-NH4+) on the potassium uptake and potassium concentration changes on the recycled solution and the development of empirical models that permit the prediction of the potassium nutritional needs of Dieffenbachia amoena, ‘Tropic Snow’. To achieve this, potassium uptake has been correlated to temperature, vapor pressure deficit, global radiation, and leaf area index. The plants were placed in a Buried Solar Greenhouse, the plants being supplied with equal amounts of nitrogen, differing in the percentage of the N-form applied (NO3–:NH4+): Ta (100:0), Tb (50:50), and Tc (0:100). Seasons (winter and summer) generate important differences in the potassium concentration changes in the recycled solution but are not influenced by the nitrogen form. In winter, the potassium concentration remains constant, whereas in summer conditions, there is a higher decrease. This difference in behavior should be considered in the nutritive solution formulation. The nitrogen form applied does not affect potassium uptake. The study also indicates the possibility of predicting the potassium (K) uptake using the proposed models. K uptake can be estimated with a model dependent on the leaf area index, and potassium uptake concentration can be estimated with K uptake through the model and the experimental water uptake.
A Comparison of Techniques for Determining Nitrogen Release from Polymer-coated Urea in the Field
Authors: Wilson Melissa L. , Rosen Carl J. , Moncrief John F.
Published: February 2019

Although laboratory analyses of nitrogen (N) release from polymer-coated urea (PCU) are available for most brands of PCU, data are lacking for release patterns under field conditions. Release rate studies for PCU are often time-consuming and expensive as a result of the need for multiple chemical analyses. We compared the N release using a weight loss method with a direct chemical analysis method for two types of PCU (Agrium PCU, Agrium U.S. Inc.; Kingenta PCU, Shandong Kingenta Ecological Engineering Co., Ltd.). The PCU prills were placed in a mesh bag and N loss from the prills over time was determined indirectly by loss in weight. The N content of the prills was determined by the combustion method to verify the weight method technique. A second study was conducted to determine if the type of mesh bag material affects the percentage of N released. For this study, mesh bags were constructed from two different materials with two different hole sizes and total amount of open area. Overall, regression analysis suggested that the percentage of N released as estimated by the weight method and combustion method was not significantly different over the growing season for two types of PCU. The mesh bags made of the material with smaller holes and less open area resulted in significantly less N release than the material with more open area and larger holes. Overall, these results suggest that the weight method can be reliably used as a substitute for chemical analysis to determine N release characteristics of PCU, but mesh bag materials must be taken into consideration to reduce errors. The best technique to determine N release may be one that does not include a mesh bag; however, until that method is developed, using a larger hole size is recommended.
Open-pollination Provides Sufficient Levels of Cross-pollen in Spanish Monovarietal Olive Orchards
Authors: Pinillos Virginia , Cuevas Julián
Published: February 2019

Most Spanish olive orchards are monovarietal as a result of the farmer's belief that the species does not require cross-pollination. Paradoxically, accumulated evidence from controlled experiments demonstrates that olive is partially self-incompatible and that cross-pollination increases yield and fruit quality in this wind-pollinated crop. With the aim of assessing cross-pollination deficit in large plots of the most widespread olive oil cultivar in Spain, fruit set was compared in two solid orchards of ‘Picual’ in response to self-, open-, and artificial cross-pollination. In both orchards, ‘Picual’ behaved as a self-incompatible cultivar with reduced fruit set under self-pollination (index of self-incompatibility = 0.21). However, cross-pollination rarely increased fruit set in comparison with open-pollination. Bagging experiments demonstrated that open-pollination provided enough cross-pollen to induce high levels of fruit set. The increase in fruit set in response to mechanical application of cross-pollen was limited to the trees directly receiving the pollen flow and only in one orchard. Consistently, airborne pollen concentration after a single terrestrial application significantly fits a decay curve with a short dispersal. In contrast with the limited dispersal of single mechanical applications, open-pollination results suggest that trees from plantations at least 250 to 500 m away are acting as unsuspected pollenizers. This is probably taking place to some extent in most traditional olive districts in Spain, and it explains why farmers have never demanded pollination designs in this crop. Modern homogeneous plantations can, however, change this situation dramatically and give rise to pollination deficits.
Pollen Morphology and Anatomy of Cornelian Cherry (Cornus mas L.) Cultivars
Authors: Mert Cevriye
Published: February 2019

Morphology and ultrastructure of pollen grain were described for six cornelian cherry (Cornus mas L.) cultivars (Degirmendere, Erkenci Degirmendere, İri Bardak, Yuvarlak Bardak, Uzun Memeli, and Bugur) using light microscopy and both scanning and transmission electron microscopy. Pollen grains of cornelian cherry cultivars are trizonocolporate, the germinal furrow extending almost the full length of the grain axis. Pollen grain length for the studied cultivars ranged from 23.63 to 25.13 μm. Two different pollen shapes were observed: oblate spheroidal and prolate spheroidal. Significant changes in various layers of the pollen wall are as follows: the thickness of the intine: 233.1 to 406.4 nm, exine: 510.2 to 842.7 nm, and total wall 851.4 to 1175.8 nm. Percentages of abnormal pollen grains ranged from 3.9% to 27.6% among the cultivars. Abnormal pollen grains were categorized as: 1) shrunken pollen grains of abnormal appearance with little cytoplasm; 2) pollen grains of normal appearance with little or no cytoplasm; and 3) shrunken, abnormal pollen grains of elliptical shape with a colpate-type aperture.
Effects of Type of Explant and Dark Preconditioning on Bud Formation in Habenaria radiata (Thunb.) in Vitro
Authors: Mitsukuri Kazuhiko , Arita Takaya , Johkan Masahumi , Yamasaki Satoshi , Mishiba Kei-ichiro , Oda Masayuki
Published: February 2019

Habenaria radiata is a terrestrial orchid with beautiful bird-shaped petals. The wild H. radiata population has been severely affected by environmental disruption and overexploitation. In micropropagation of H. radiata, although aseptic germination has been studied, tissue culture methods have not yet been established. Shoot apexes and leaf explants from vegetative plants and flower stalks, stolons, and floret explants from reproductive plants were chosen for this study. Explants were cultured on half-strength inorganic salts and full-strength vitamins of Murashige and Skoog (1/2 MS) medium containing 30 g·L−1 sucrose, 8 g·L−1 agar (pH 5.6) supplemented with 4.44 μM N6-benzyladenine, and 0.54 μM α-naphthaleneacetic acid. After 8 weeks of culture, the highest survival rate was obtained with floret explants excised from plants at the reproductive phase. In floret culture, the number of adventitious bud formation per explant was 5.4 per upper floret and 4.0 per lower floret. Dark preconditioning, which inhibited browning and contamination, of explants before shoot apex culture increased survival rates of explants (53%) and bud formation (83%). Consequently, a tissue culture method using florets and shoot apexes as explant material was established for H. radiata.
Horticultural Evaluation of New Citrus latipes Hybrids as Rootstocks for Citrus
Authors: Reforgiato Recupero Giuseppe , Russo Giuseppe , Recupero Santo , Zurru Roberto , Deidda Bruno , Mulas Maurizio
Published: February 2019

In 1968, the CRA-Research Center for Citriculture and Mediterranean Crops (CRA-ACM) started a research program aimed at breeding citrus rootstocks. The monoembryonic species C. latipes (Swing.) Tan. was used as the female parent; trifoliate orange [Poncirus trifoliata (L.) Raf.], sour orange, and volkamer lemon (C. volkameriana Pasq.) were used as male parents. The behavior of some of these hybrids tested with other standard rootstocks in Sicily and Sardinia was evaluated. The cultivars under comparison included ‘Washington’ navel orange and ‘SRA 92’ clementine in Sardinia and ‘Tarocco’ orange in Sicily. Our results showed the dramatic influence of rootstock on plant growth and yield; only minor effects on fruit quality were observed. Among the standard rootstocks tested, Swingle citrumelo provided the highest yield. Some of the tested hybrids (F5 P12, F6 P12, and F6 P13) may improve plant yield, thus maintaining good fruit quality. Encouraging data obtained with these hybrids may justify the use of monoembryonic species of the Papeda subgenus for breeding citrus rootstocks.
Cloning and Characterization of a Self-compatible Sf Haplotype in Almond [Prunus dulcis (Mill.) D.A. Webb. syn. P. amygdalus Batsch] to Resolve Previous Confusion in Its Sf-RNase Sequence
Authors: Hanada Toshio , Fukuta Kyoko , Yamane Hisayo , Esumi Tomoya , Tao Ryutaro , Gradziel Thomas M. , Dandekar Abhaya M. , Fernández i Martí Ángel , Alonso José M. , Socias i Company Rafel
Published: February 2019

Most of the self-compatible (SC) cultivars of almond [Prunus dulcis (Mill.) D.A. Webb. syn. P. amygdalus Batsch] have the Sf haplotype. In this study, we cloned and characterized the S locus region of the Sf haplotype of SC ‘Lauranne’. The relative transcriptional orientation of SFBf and Sf-RNase and the physical distance between them are similar to those of other functional self-incompatible (SI) S haplotypes of Prunus, indicating that the genomic structure of the SC Sf haplotype appears to be intact. Although there is no apparent mutation in the coding sequence of SFBf, the Sf-RNase sequence in this study and previously reported Sf-RNase sequences show discrepancies. First, as opposed to previous indications, the ‘Lauranne’ Sf-RNase sequence encodes a histidine residue in place of a previously reported arginine residue in the conserved C2 region of Prunus S-RNase. Direct sequencing of the polymerase chain reaction products from the Sf-RNase of ‘Tuono’ confirmed that ‘Tuono’ Sf-RNase also encodes the histidine residue. We found another difference in the ‘Lauranne’ Sf-RNase sequence and other reported Sf-RNase sequences. Namely, ‘Lauranne’ Sf-RNase encodes a phenylalanine residue in place of a previously reported leucine residue in the conserved C5 region of Prunus S-RNase. This is also the case for ‘Tuono’ Sf-RNase. Expression analysis of Sf-RNase and SFBf by reverse transcriptase–polymerase chain reaction showed that Sf-RNase transcripts were barely detectable in pistil, whereas SFBf transcripts were accumulated at a similar level to the level that was observed with SFB of other functional SI S haplotypes of almond. We discuss the possible molecular mechanisms of SC observed with the Sf haplotype with special references to the expression of Sf-RNase.
Correlation Between L*a*b* Color Space Values and Carotenoid Content in Pumpkins and Squash (Cucurbita spp.)
Authors: Itle Rachel A. , Kabelka Eileen A.
Published: February 2019

Carotenoids play an important role in human health by acting as sources of provitamin A or as protective antioxidants. Pumpkins and squash (Cucurbita spp.) are excellent dietary sources of carotenoids. The diversity and range of carotenoid types and concentrations within pumpkins and squash provide a means to increase the nutritional value of this crop through plant breeding. Breeding requires reliable estimates of carotenoid types and concentrations to distinguish differences among breeding material. One method used for carotenoid identification and quantification is high-performance liquid chromatography (HPLC). It is a highly sensitive and reproducible method but expensive and time-consuming. In contrast, colorimeters objectively describing visible color are relatively inexpensive and easy to use. The objective of this research was to determine if the carotenoid content within pumpkin and squash measured by HPLC was correlated with colorimeter L*a*b* color space values. Cultigens (cultivars, heirlooms, and PIs) representing white, yellow, and orange flesh color were grown at multiple locations using a randomized complete block design with two replicates at each location. Fruit flesh of each cultigen was evaluated using HPLC and colorimetric analysis. Strong correlations were found between color value a* and total carotenoids (r = 0.91) and color value b* and chroma with lutein (r = 0.87). Regression equations based on these correlations will be useful for estimating carotenoid type and concentrations. These close associations will also assure that breeding for enhanced carotenoid content within pumpkins and squash can be achieved using an easy-to-use and inexpensive method.
In Vitro Induction of Tetraploids in Dieffenbachia × ‘Star Bright M-1’ by Colchicine
Authors: Henny Richard J. , Holm James R. , Chen Jianjun , Scheiber Michelle
Published: February 2019

Colchicine application successfully induced tetraploids from in vitro-cultured diploid Dieffenbachia × ‘Star Bright M-1’. Shoot clumps, each with six to eight small, undifferentiated shoot primordia, were cultured in liquid Murashige and Skoog (MS) medium and treated with colchicine at rates of 0, 250, 500, or 1000 mg·L−1 for 24 h. In vitro survival of shoot clumps significantly decreased as colchicine concentrations increased. Shoot clumps that survived were transferred to colchicine-free MS medium containing 2.0 mg·L−1 N6-isopentenyl) adenine and 0.10 mg·L−1 indole-3-acetic acid. Shoots were harvested during four subsequent subcultures and planted in a soilless substrate in a shaded greenhouse. The number of plants that survived 6 months after ex vitro planting was 690, 204, 59, and 69 for colchicine treatments at 0, 250, 500, and 1000 mg·L−1, respectively. The 332 plants from colchicine treatments along with 90 control plants (selected from 690 in the control treatment) were evaluated morphologically in a shaded greenhouse. Overall plant growth, including crown height, plant canopy, and leaf size, of colchicine-treated plants was significantly less than controls. Based on the growth data, 10, 32, 15, and 16 plants from the 0, 250, 500, and 1000 mg·L−1 colchicine rates, respectively, were selected and analyzed by flow cytometry. Flow cytometry confirmed the presence of 13 tetraploids and 29 mixoploids among the 63 colchicine-treated selections; all 10 plants from the control were diploid. A colchicine rate of 500 mg·L−1 produced a higher percentage of tetraploids (10.2%) than did the 250 (2.9%) or 1000 mg·L−1 (1.4%) rates. Subsequent comparisons showed tetraploids had significantly smaller and thicker leaves, greater specific leaf weights, and longer stomata than diploids. Tetraploids also showed increased net photosynthetic rate, decreased gS, decreased intercellular CO2 concentration, decreased transpiration rate, and increased water use efficiency. Tetraploids appeared robust and their smaller size could make them potentially more durable plants used as living specimens for interior decoration.
Productivity and Characteristics of American Elderberry in Response to Various Pruning Methods
Authors: Thomas Andrew L. , Byers Patrick L. , Ellersieck Mark R.
Published: February 2019

American elderberry [Sambucus canadensis L.; Sambucus nigra ssp. canadensis (L.) Bolli] is being increasingly cultivated in North America for its edible fruit and flowers, yet it remains largely undeveloped as a horticultural crop. Elderberry is a shrub that produces fruit on both new and old wood, thereby offering unique pruning management opportunities and challenges. The objective of this study was to document the response of American elderberry to various pruning methods in terms of flowering, fruit yield, phenology, plant growth, and incidence of disease and arthropod pests and to consider the impact of various pruning methods on horticultural management. Four pruning treatments (annual removal of all shoots, biannual removal of all shoots, annual selective pruning, and no pruning) were studied among three cultivars at two Missouri sites over 5 years. Although significant interactions among experimental effects made interpretation challenging, several trends were evident. Annual selective pruning was an excellent way to manage elderberries with mean yields of 1086 g/plant across all experimental parameters; however, pruning to the ground annually or biannually also resulted in satisfactory yields (855 and 1085 g/plant, respectively) with a fraction of pruning labor involved. Pruning plants to the ground consistently resulted in fewer, but larger, fruiting cymes compared with selectively pruned or unpruned plants, which may be important in terms of harvest efficiency. Pruning treatment generally affected the time of flowering and fruit ripening; plants that flowered only on new stems (after removal of all shoots) ripened fruit 14 to 21 days later than plants that fruited on old wood. Although annually pruned plants generally yielded lower, the plants remained vigorous and productive, and this pruning management technique may have numerous advantages over other pruning methods.
Trellis Tension Monitoring Improves Yield Estimation in Vineyards
Authors: Blom Paul E. , Tarara Julie M.
Published: February 2019

Most yield estimation practices for commercial vineyards are based on longstanding but individually variable industry protocols that rely on hand-sampling fruit on one or a small number of dates during the growing season. Limitations associated with the static nature of yield estimation may be overcome by deployment of trellis tension monitors (TTMs), systems that provide dynamic measurement of changes in the tension of the main trellis support wire. In 10 commercial vineyards from which two commercial juice processors annually collect data to derive yield estimates, TTMs were installed. Processor and TTM data were subjected to three permutations of the basic linear computational approach to estimating yield and their accuracies evaluated given known harvested yield at various spatial scales. On average, TTM data produced more accurate estimates of actual yield than did the computational protocols of the juice processors. There was high vineyard-to-vineyard variability in the accuracy of the estimate under all approaches, even from those permutations designed to match the spatial scale of the data collected for yield estimation with the spatial scale of the actual harvested yield. The processor protocols appear to be more sensitive than the TTM approach to the selection of the antecedent years used for comparison with the current year's data. Trellis tension monitoring may be useful to supplant traditional, labor-intensive yield estimation practices or to supplement longstanding practices with real-time information that can be applied to dynamic revision of static yield estimates.
Growth and Yield of Young ‘Valencia’ Sweet Orange Trees Treated with Insecticides
Authors: Powell Charles A. , Ritenour Mark A. , Bullock Robert C.
Published: February 2019

The trunk diameter of ‘Valencia’ sweet orange trees tested with seven insect control strategies was measured annually for the first 5 years after planting. Yield data (marketable fruit per tree) were collected after the fourth and fifth years. The insect control treatments were Admire (imidacloprid) applied at 12, 6, 3, or 2-month intervals; Temik (aldicarb) applied annually; Meta-Systox-R (oxydemeton-methyl) applied annually; or no insect control. Trunk diameter was significantly increased by Temik treatment at 1 and 2 years after planting. Six annual applications of Admire (at 2-month intervals) significantly increased trunk diameter 2 years after planting. None of the other treatments affected trunk diameters compared with the control. There were no trunk diameter differences among treatments at 3, 4, or 5 years after planting. Both Temik applied annually and Admire applied every other month or every 3 months significantly increased yield.
Manipulation of Light Environment to Produce High-quality Poinsettia Plants
Authors: Mata Diego A. , Botto Javier F.
Published: February 2019

The phytochromes, a family of photoreceptors that maximally absorb red (R) and far-red (FR) light, play an important role in defining the architecture of the plant and consequently its value in the market. In this work, we evaluated the manipulation of light quality as an alternative to the use of plant growth regulators (PGRs) to produce poinsettia plants (Euphorbia pulcherrima Willd. ex Klotzsch) without affecting commercial quality parameters. ‘Freedom Red’ poinsettia plants were cultivated in two light environments characterized by different R/FR ratios in combination with or without one application of PGR. We used a photoselective film that significantly reduced the FR component of the light and a transparent film to obtain high and low R/FR ratios (5.7 and 1.1, respectively). Plants cultivated under a high R/FR ratio were shorter and more compact than those grown under transparent film. Other quality characters like bract and leaf area, dry weight, stem diameter, number of lateral branches, and plant width did not differ significantly between light treatments. Flowering time was slightly delayed in plants grown under a high R/FR ratio compared with those cultivated under the control treatment. Additive effects were detected between light quality and PGR factors indicating that light quality manipulation is an alternative strategy to reduce or to replace the use of PGRs in commercial production systems that usually require several PGR applications.
How Sodium Chloride Concentration in the Nutrient Solution Influences the Mineral Composition of Tomato Leaves and Fruits
Authors: Giuffrida Francesco , Martorana Marianna , Leonardi Cherubino
Published: February 2019

Tomato plants (Solanum lycopersicum L. cv. Durinta) were grown in an open soilless system to evaluate the effects of sodium chloride (NaCl) concentration in the nutrient solution on the ion compositions in plant tissues. The treatments were defined by a factorial combination of five NaCl concentrations and three leaves position/age and two fruits' position. Seedlings were transplanted in perlite and, 7 days after transplanting, five salinity treatments were imposed by adding 7, 21, 37, 49, or 64 mm of NaCl to the nutrient solutions; the final electrical conductivities were: 2.7, 4.5, 6.0, 7.5, and 8.6 dS·m−1, respectively. Increased salinity in the nutrient solution resulted in a reduction in tomato dry matter (from 534 to 375 g per plant) and in a linear increase in sodium (from 0.37% to 1.39%) and chloride (from 1.75% to 5.73%) in the leaves as well as in the fruit tissues (from 0.08% to 0.26% for sodium and from 0.63% to 1.34% for chloride). Leaf under the first cluster showed higher levels of sodium (+54%) and chloride (+32%) than leaf under the fifth cluster and old leaf accumulated more sodium (+15%) and chloride (+25%) than younger ones. The exposure of the tomato plants to increasing salinity resulted in a linear decline in nitrate (from 1.21% to 0.50%), total nitrogen (from 3.31% to 3.03%), sulphate (from 3.71% to 3.12%), and potassium leaves (from 2.76% to 1.51%); the potassium reduction was more evident in younger leaves than in older ones. All macronutrients, except calcium, decreased in the fruit tissues with increasing NaCl concentration in the nutrient solution. However, for phosphate, the reduction of the ion concentration was evident only in the fruit from the fifth cluster (–35%). The position of the fruit on the plant significantly affected the concentration of ion, which was higher for all determined ions in the fruit of the first truss. The levels of Na+ and Cl– found in the plant tissue seem to confirm the hypothesis that the plant dry biomass reduction may also be traced to the toxicity of these ions as a consequence of this high concentration. On the other hand, although generally influenced by antagonism with sodium and chloride, the amount of main macronutrients did not reach deficiency levels that influenced the growth processes, except in the case of potassium.
An Efficient Procedure for Regeneration from Leaf-derived Calluses of Lonicera macranthoides ‘Jincuilei’, an Important Medicinal Plant
Authors: Wang Xiaoming , Chen Jianjun , Li Yongxin , Nie Qiying , Li Junbin
Published: February 2019

‘Jincuilei’ is a mutant selected from Lonicera macranthoides Hand.-Mazz. It produces abundant flowers that never open with a chlorogenic acid (CGA) content up to 6.0%. Propagation through rooting or grafting has only a 30% survival rate. This study was undertaken to establish an efficient protocol for rapidly regenerating this mutant. Leaf explants were inoculated on Gamborg's B5 medium supplemented with different concentrations of 6-benzyladenine (BA) and 2,4-dichlorophenozyacetic acid (2,4-D). The optimal combination for callus induction was 4.4 μm BA with 2.26 μm 2,4-D, which resulted in 86.7% of leaf explants producing calluses in 4 weeks. Calluses produced from this optimal medium were cultured on B5 medium containing different concentrations of kinetin (KT) and α-naphthalene acetic acid (NAA). The best formulation for shoot induction was B5 medium containing 0.9 μm KT and 5.4 μm NAA in which 73.4% of cultured calluses produced shoots in 8 weeks, and shoot numbers ranged from three to six per callus piece (1 cm3). Adventitious shoots were cut and rooted in half-strength Murashige and Skoog medium supplemented with 14.8 μm 3-indolebutyric acid. Roots initiated 10 d after culture, and rooting percentages ranged from 98% to 100%. Plantlets grown in a container substrate in a shaded greenhouse had over a 95% survival rate. During the last 6 years, over four million plantlets were regenerated using this established procedure, and there was no somaclonal variation. Fresh and dry weights of 1000 flowers, CGA contents, and dry flower yields of the regenerated plants were not significantly different from those of the stock ‘Jincuilei’ propagated by cutting, indicating that plants regenerated from this established procedure were stable. This established in vitro culture method has led to rapid commercial production of this medicinal plant on more than 1500 ha of production field.
In Vitro Germination and Dormancy Responses of Hydrangea macrophylla and Hydrangea paniculata Seeds to Ethyl Methane Sulfonate and Cold Treatment
Authors: Greer Stephen Patrick , Rinehart Timothy A.
Published: February 2019

To determine the optimal conditions for mutagenesis of Hydrangea macrophylla (Thunb.) Ser. and Hydrangea paniculata Siebold, cold-treated and untreated seed from representative cultivars were exposed to 0.5%, 2.5%, and 5.0% ethyl methane sulfonate (EMS). Most untreated H. macrophylla seed exposed to 2.5% and 5.0% EMS had substantially lower germination percentages. H. paniculata seed germination percentages did not differ from controls until EMS concentrations reached 5.0%. Cold treatment of H. macrophylla and H. paniculata seed made germination more tolerant to all concentrations of EMS tested and increased germination of most H. macrophylla cultivars when compared with lower dosages. Germination of cold-treated seed from H. paniculata cultivars rose substantially above control levels even at the highest dosages. For the most part, we observed more nondormant seed, or seed available for germination, but less viability with increasing EMS dosage in untreated Hydrangea L. seed versus controls. In contrast, cold-treated seed displayed higher levels of mutagen tolerance and nondormancy versus controls when exposed to these same doses of EMS.
Organic Fertilizers for Greenhouse Tomatoes: Productivity and Substrate Microbiology
Authors: Zhai Zhengli , Ehret David L. , Forge Tom , Helmer Tom , Lin Wei , Dorais Martine , Papadopoulos Athanasios P.
Published: February 2019

Organic fertilizer regimens consisting of combinations of composts (yard waste, swine manure, or spent mushroom substrate) and liquid fertilizers (fish- or plant-based) were evaluated against conventional hydroponic fertilizers in two experiments with greenhouse tomatoes grown in peat-based substrate. Crop yield and fruit quality were evaluated and several assays of substrate microbial activity and community profiles (fluorescein diacetate analysis and EcoLog, values, nematode counts) were conducted. Crops grown in 20% to 40% compost (yard waste or yard waste plus swine manure) plus a continuously applied liquid source of organic potassium (K), calcium (Ca), magnesium (Mg), and sulphate (SO4) could not be sustained more than 1 month before nutrient deficiencies became visible. Supplementation with a nitrogen (N)- and phosphorus (P)-containing plant-based liquid fertilizer at the point when plant deficiencies became apparent subsequently produced yields ≈80% that of the hydroponic control. In a second experiment, the proportion of mushroom or yard waste compost was increased to 50% of the mix, and liquid delivery of K, Ca, Mg and SO4 plus either plant-based or fish-based N- and P-containing liquid feeds was started at the date of transplanting. In this case, organic yields equal to that of the hydroponic control (8.5 kg/plant) were observed in some treatments. The most productive organic treatment was the mushroom compost supplemented with a low concentration of the plant-based liquid fertilizer. In general, organic tomatoes had a lower postharvest decay index (better shelf life) than did the hydroponic controls, possibly as an indirect consequence of overall reduced yield in those treatments. High concentrations of both organic liquid feeds resulted in lower yields as a result of treatment-induced fusarium crown and root rot. In contrast to some previous studies, those treatments showing fusarium crown and root rot also had the highest gross microbial activity. Measures of gross microbial activity and numbers of microbivorous nematodes were higher (average of 37% and 6.7 times, respectively) in compost/organic feed treatments than in the hydroponic control. Community physiological profiles of the bacterial populations, on the other hand, did not differ between organic and hydroponic treatments. Nematode populations were significantly correlated with gross microbial activity in the organic treatments.
Agronomical Response and Water Use Efficiency of Sweet Pepper Plants Grown in Different Greenhouse Substrates
Authors: del Amor Francisco M. , Gómez-López María D.
Published: February 2019

An experiment was carried out to assess the influence of three types of substrate on the growth and yield of sweet pepper (Capsicum annuum L.). Plants were grown during three cycles (2005, 2006, and 2007) in coconut coir dust (CC), urea formaldehyde foam (UF), and rice hull (RH) amended with polyacrylamide gel (water absorber). Growth parameters, dry weight (DW) of vegetative and generative parts, intercepted radiation, water uptake, total fruit yield, and quality parameters were analyzed. Plant height, total leaf fresh weight, and stem diameter were higher in CC and lower for the RH substrate, which also showed lower yields and fruit quality. Accumulated dry matter was modeled according to water uptake and substrate using a linear function. Upper and lower limits in water use efficiency, between 2.5 and 5.7 g DW/L, are linked to the irrigation strategies and crop seasons. Light use efficiency (LUE) under different conditions was also determined to predict plant dry matter and a unique value was obtained for the three substrates (LUE = 0.91 g/MJ). Three different irrigation strategies were proposed for each substrate as a function of intercepted radiation and defining an α coefficient (expressed in mm/m2/MJ) that coupled crop and climate components. These crop characterization and prediction tools could help to optimize plant growth and yield for environmentally friendly substrates.
Establishment and Maintenance During Establishment of Hybrid Bluegrass (P. arachnifera Torr. × P. pratensis L.) in the Transition Zone
Authors: Teuton Travis C. , Sorochan John C. , Main Christopher L. , Mueller Thomas C.
Published: February 2019

The transition zone is one of the hardest places to maintain high-quality turfgrasses, and the overall research objective was to determine best management practices to establish new turf cultivars in this zone. Hybrid bluegrasses (P. arachnifera Torr. × P. pratensis L.) have been bred for heat and drought tolerance and may offer a new alternative to other turfgrasses. The specific cultivars examined in this research were ‘Thermal Blue®’ and ‘Dura Blue®’. Experiments were conducted during 2003, 2004, and 2005 in Knoxville, TN. ‘Thermal Blue’ was seeded at 50, 100, 150, 200, and 250 kg·ha−1 of seed. ‘Thermal Blue's’ ideal seeding rate was between 100 and 150 kg·ha−1 of seed in 2003 and 50 kg·ha−1 in 2004. ‘Thermal Blue’ was also seeded in January, April, July, and September of each year with 100 kg·ha−1 of seed. All seeding dates took ≈11 months to become well established. However, July seeding produced poor turf quality (less than 6) and was the only seeding date deemed unacceptable. ‘Thermal Blue’ and ‘Dura Blue’ were fertilized with ammonium nitrate at 100, 200, and 300 kg N/ha/year and urea formaldehyde at 200 and 300 kg N/ha/year starting in March of each year. These treatments were maintained at 2-, 3.5-, and 5-cm mowing heights. ‘Thermal Blue’ had higher quality evaluations and produced more clippings than ‘Dura Blue’ throughout the year. Higher fertility regimens increased quality evaluations in April but decreased quality evaluations in October. Increasing the mowing height improved turf quality and decreased biomass production for both grasses. A proposed optimum method for establishment included seeding ‘Thermal Blue’ in April at 150 kg·ha−1 and fertilizing with 300 kg·ha−1 of nitrogen and them mowing at 5-cm height. ‘Thermal Blue’ and ‘Dura Blue’ are adapted for the transition zone, but summer heat stress may cause turf quality decrease in the fall.
Expression of a Gene Encoding the Carrot HSP17.7 in Escherichia coli Enhances Cell Viability and Protein Solubility Under Heat Stress
Authors: Kim Hyesoon , Ahn Yeh-Jin
Published: February 2019

DcHSP17.7, a small heat shock protein from carrot (Daucus carota L.), was expressed in Escherichia coli to examine its functional mechanism under heat stress. When transformed cells expressing DcHSP17.7 were exposed to 50 °C for 1 h, the number of viable cells was ≈4-fold higher than that of control. When the amount of soluble proteins was compared, it was more than twofold higher in transformed cells expressing DcHSP17.7 than that in control, suggesting that DcHSP17.7 may function as a molecular chaperone preventing heat-inducible protein degradation. Native-PAGE followed by immunoblot analysis showed that in transformed E. coli, DcHSP17.7 was present in an oligomeric complex, ≈300 kDa in molecular mass, on isopropyl b-D-thiogalactopyranoside treatment. However, the complex rapidly disappeared when bacterial cells were exposed to heat stress. In carrot, DcHSP17.7 was found in the similar-sized complex (≈300 kDa), but only during heat stress (40 °C), suggesting that the functional structure of DcHSP17.7 may be different in transformed E. coli from that in carrot.
Gibberellic Acid Promotes Seed Germination in Penstemon digitalis cv. Husker Red
Authors: Machado de Mello Anderson , Streck Nereu Augusto , Blankenship Erin E. , Paparozzi Ellen T.
Published: February 2019

Penstemon seed often shows an inconsistent or a low germination percentage. Although most select cultivars are propagated by cuttings, for export to other countries, seed is preferred. Three experiments were conducted to determine if soaking seed in gibberellic acid (GA3) would increase seed germination of Penstemon digitalis cv. Husker Red. GA3 concentrations used were 0, 10, 50, 100, 200, and 500 mg·L−1 (first experiment); 0, 500, 1000, and 1500 mg·L−1 (second experiment); and 0, 500, and 1000 mg·L−1 (third experiment). The first and second experiments were conducted in a growth chamber, whereas the third experiment was conducted in both a growth chamber and greenhouse with seeds either covered or not covered by the mix. In all experiments, GA3 increased the percentage and rate of seed germination. The 1000 mg·L−1 GA3 was the best treatment. In the third experiment, percentage and rate of seed germination were the highest for seeds grown inside of the growth chamber, probably as a result of the consistency of temperatures and darkness. In the greenhouse, the percentage of seeds that germinated and the rate of germination were similar whether or not the seeds were covered with mix and whether they received either the 500 or 1000 mg·L−1 GA3 treatment.
Ethidium Bromide-induced Mutations from Inflorescence Cultures of Indiangrass
Authors: Stephens Loren C.
Published: February 2019

Immature inflorescences of a Sorghastrum nutans (L.) Nash selection were cultured on CCm medium with 5 mg·L−1 2,4-dichlorophenoxyacetic acid and 1 mg·L−1 N6-benzyladenine (BA) for 5 weeks. Callused inflorescence cultures were placed on CCm medium with 1 mg·L−1 BA (CCmB1) and 0 or 250 mg·L−1 ethidium bromide (EtBr) for 24 h. Cultures were transferred to CCmB1 without EtBr for shoot regeneration and then to CCm without plant growth regulators for rooting. Rooted shoots were transferred to soil under greenhouse conditions and then to the field. Fifteen putative M1 mutants with atypical phenotypes were detected among 71 EtBr-treated regenerants. Two self-incompatible putative M1 mutants were progeny-tested by using a wild-type Indiangrass seedling as the pollen parent. M1 selection ISU06-35 was a dwarf mutant whose M2 testcross progeny segregated 1:1 tall:dwarf seedlings. M1 selection ISU06-56 was a red-flowered mutant whose M2 testcross progeny segregated 1:1 green-flowered:red-flowered seedlings. These results are consistent with both M1 mutants being dominant nuclear mutations.
Differential Cold Acclimation Ability of Petunia spp.
Authors: Walworth Aaron E. , Warner Ryan M.
Published: February 2019

Freezing tolerance of many plant species increases after exposure to low, nonfreezing temperatures, a process termed cold acclimation. In some species, shortened photoperiods also bring about an increase in freezing tolerance. Within the plant family Solanaceae, species vary widely in cold acclimation ability. The objectives of this work were to examine the effects of low temperature and photoperiod on cold acclimation of Petunia hybrida (Hook.) Vilm. ‘Mitchell’ and to evaluate cold acclimation of several Petunia species by measuring freezing tolerance using an electrolyte leakage assay on leaf tissue discs. Temperature, but not photoperiod, influenced cold acclimation of P. hybrida. Whether grown under long days or short days, nonacclimated plants had an EL50 value (temperature at which 50% of cellular electrolytes are lost) of ≈–2 °C. Plants acclimated by gradual cooling at temperatures of 15 °C, 10 °C, and 3 °C for 7 days each reached an EL50 of ≈–5 °C regardless of photoperiod. Exposure to 3 °C under short days for 1 or 3 weeks resulted in EL50 temperatures of –3.9 and –4.9 °C, respectively. Freezing tolerance of petunia species P. exserta Stehmann, P. integrifolia (Hook.) Schinz & Thell., P. axillaris (Lam.) Britton et al. (USDA accessions 28546 and 28548), and P. hybrida ‘Mitchell’ was similar before cold acclimation, but varied from –5 °C for P. exserta to –8 °C for P. axillaris (accession 28548) after cold acclimation. Our results demonstrate the cold acclimation ability of Petunia spp. and identify wild germplasm sources with potential usefulness for improving freezing tolerance of cultivated petunia.