bluuebunny/crossref_metadata_2025 huggingface dataset:
Root Development and Profile Characteristics of Bermudagrass and Zoysiagrass
Authors: Fuentealba Maria P. , Zhang Jing , Kenworthy Kevin E. , Erickson John E. , Kruse Jason , Trenholm Laurie E.
Published: February 2019

Irrigation for commercial and residential turf is becoming limiting, and water scarcity is one of the long-term challenges facing the turfgrass industry. Potential root development and profile characteristics of turfgrass provide important information regarding their drought resistance mechanisms and developing drought-resistant cultivars. The objective of this study was to determine the potential root development and root profile characteristics of two bermudagrass species and two zoysiagrass species using experimental lines and commercial cultivars. The species evaluated in the study were: African bermudagrass (Cynodon transvaalensis Burtt-Davy), common bermudagrass (CB) [Cynodon dactylon (L.) Pers. var. dactylon], Zoysia japonica (ZJ) (Steud), and Zoysia matrella (ZM) L. Plants were grown outdoors in clear acrylic tubes encased in poly vinyl chloride (PVC) sleeves. The experimental design was randomized complete block design with four replications. Rates of root depth development (RRDD) during the first 30 days were obtained. Root length density (RLD) in four different horizons (0–30, 30–60, 60–90, and 90–120 cm) was determined 60 days after planting. Specific root length (SRL, m·g−1) was also calculated dividing total root length by total root dry weight (RDW). The root depth in four turfgrass species increased linearly during the first 30 days after planting. Common bermudagrass (CB) had high RRDD and uniform RLD in different horizons, while ZM accumulated the majority of its roots in the upper 30 cm. Z. matrella had higher RLD than CB in the upper 30 cm. African bermudagrass had higher SRL than CB. There was limited variation within the two African bermudagrass genotypes studied except at the lowest horizon (90–120 cm). Two genotypes in CB and ZJ, respectively, including ‘UF182’ (ZJ), which consistently ranked in the top statistical group for RRDD, and RLD for every horizon, and ‘UFCD347’ (CB) demonstrated greater RLDs in the lower horizons in comparison with the commercial cultivars.
Genetic Variability and Heritability Estimates of Nutritional Composition in the Leaves of Selected Cowpea Genotypes [Vigna unguiculata (L.) Walp.]
Authors: Gerrano Abe Shegro , Adebola Patrick Olusanmi , Jansen van Rensburg Willem Sternberg , Venter Sonja Louise
Published: February 2019

Cowpea is indigenous to the African continent and is grown for its leaves and grain in different countries of the world. The objective of this study was to determine the variability and heritability of mineral and crude protein contents in the leaves of selected cowpea genotypes grown in South Africa. The trials consisted of twenty five cowpea genotypes evaluated for two cropping seasons. The combined mean values showed wide genetic variation in the mineral elements evaluated. The mean values of calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varied from 2.23 to 3.69 mg·kg−1; 6.96 to 14.15 mg·kg−1; 311.30 to 1049.95 mg·kg−1; 1.13 to 1.74 mg·kg−1; 0.36 to 0.70 mg·kg−1; 130.08 to 186.42 mg·kg−1; 126.62 to 307.87 mg·kg−1; 0.27 to 0.39 mg·kg−1; and 27.76 to 43.55 mg·kg−1, respectively. The total protein content varied from 21.39% to 33.45%. The correlation analysis revealed significant degree of association between and among mineral elements and total protein content. Biometrical analysis revealed that the phenotypic variances were higher than the genotypic variances. High values of heritability estimates were also recorded for most of the evaluated traits. The principal component analysis (PCA) showed that the first three principal components contributed 71.93% of total variation among the genotypes. The study revealed that there is an ample genetic variability that can be exploited for use in breeding for nutritional quality in cowpea leaves.
Effects of Silicon in the Nutrient Solution for Three Horticultural Plant Families on the Vegetative Growth, Cuticle, and Protection Against Botrytis cinerea
Authors: Pozo Judith , Urrestarazu Miguel , Morales Isidro , Sánchez Jessica , Santos Milagrosa , Dianez Fernando , Álvaro Juan E.
Published: February 2019

The silicon (Si) percentage in the dry matter of plants is between 0.1% and 10%, and even though its role in the metabolism of plants is not absolutely clear, Si’s positive effects on plant nutrition and plant protection against both biotic and abiotic stress are well documented. However, Si is not considered to be an essential element, so it is not always present in nutrient solutions. In this paper, an experiment was carried out in the University of Almeria’s greenhouse with hydroponic lettuce, tomato, pepper, melon, and cucumber plants. A standard nutrient solution was used as a control sample and was fertigated with Si. During the four-true-leaf seedling stage, various plant growth parameters were measured, including the dry weight and the wet weight as well as the foliar surface and the cuticle thickness of both the leaf and the stem. Additionally, in the lettuce, tomato, and pepper plants, the effect of the use of Si in the nutrient solution on the protection against the pathogen Botrytis cinerea was determined by measuring the penetration of the pathogen through the cuticle and the extension of the fungal infection by using leaf discs. The results suggest that all of the studied parameters, and both the cuticle thickness and the epidermis thickness, were increased by more than 10% on average for all of the plants. In the lettuce, tomato, and pepper plants, a beneficial effect against B. cinerea was observed when the nutrient solution containing Si was used.
Impact of Kaolin Particle Film and Synthetic Insecticide Applications on Whitefly Populations Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) and Physiological Attributes in Bean (Phaseolus vulgaris) Crop
Authors: Núñez-López Diana Carolina , Ramírez-Godoy Augusto , Restrepo-Díaz Hermann
Published: February 2019

The bean crop is of great importance for human consumption as a source of protein. One of the most limiting insect pests of this crop in Colombia is the whitefly, Trialeurodes vaporariorum (Westwood). Currently, various nonchemical pest control alternatives for cleaner production are being sought. This study aimed to determine the influence of kaolin on the development of populations of whitefly in greenhouses, and its effect on the physiological characteristics of the bean crop [Phaseolus vulgaris (L.)]. This work was conducted in the greenhouses of the Universidad Nacional de Colombia, in Bogotá. Three experiments were carried out and four treatments were evaluated: 1) control (without any insecticide), 2) synthetic chemical insecticides, and foliar applications of kaolin at 3) 2.5%, and 4) 5% (W/V). Generally, the results showed a high percentage of efficacy (≈91%) on whitefly control in plants treated with 5% kaolin, compared with the plants not treated with insecticides in the three different experiments. In addition, foliar applications of kaolin decreased transpiration by 40% and enhanced by 43% the contents of leaf chlorophyll without affecting bean yield. In conclusion, the use of kaolin particle can be considered as an alternative tool in a program of agricultural management on the bean crop since it can control a high percentage of whitefly and it may help the plant physiology, especially under conditions of abiotic stress such as drought stress.
Spray and Drench Treatments of Paclobutrazol Influence Growth of Dissotis and Tibouchina
Authors: Hawkins Susan M. , Ruter John M. , Robacker Carol D.
Published: February 2019

Dissotis rotundifolia (Sm.) Triana and Tibouchina fothergillae ×pilosa are members of the Melastomataceae family with high ornamental potential. The growth habits of these species are not ideal for nursery production or shipping. D. rotundifolia grows rapidly and needs frequent pruning. T. fothergillae ×pilosa has an open growth habit and could benefit from a more compact form. The effect of the plant growth regulator (PGR) paclobutrazol on D. rotundifolia and T. fothergillae ×pilosa was assessed to determine whether it could produce plants with a more compact growth habit. Paclobutrazol was applied as a drench and a spray. Drench application was more effective in reducing the growth of both species. Spray application was effective in reducing the growth of D. rotundifolia but was not effective on T. fothergillae ×pilosa. Neither drench nor spray application delayed or reduced flowering in D. rotundifolia. T. fothergillae ×pilosa did not flower during the study. For both D. rotundifolia and T. fothergillae ×pilosa, neither drench nor spray application had an effect on root dry weight. Low-to-medium dosages were effective at controlling plant growth in D. rotundifolia and T. fothergillae ×pilosa without adverse effects on plants. Drench treatments have more persistent effects on plant growth than spray treatments.
Foliar Application of 24-Epibrassinolide Improved Salt Stress Tolerance of Perennial Ryegrass
Authors: Sun Shanshan , An Mengying , Han Liebao , Yin Shuxia
Published: February 2019

Perennial ryegrass (Lolium perenne L.) is a widely used turfgrass. In this study, the effect of exogenously applied 24-epibrassinolide (EBR) on salt stress tolerance of perennial ryegrass was investigated. The results indicated that pretreatment with four concentrations of EBR (0, 0.1, 10, 1000 nM) improved salt tolerance of perennial ryegrass. Exogenous EBR treatment decreased electrolyte leakage (EL), malondialdehyde (MDA), and H2O2 contents and enhanced the leaf relative water content (RWC), proline, soluble sugar, and soluble protein content under salt stress condition. Meanwhile, EBR reduced the accumulation of Na+ and increased K+, Ca2+, and Mg2+ contents in leaves after salt treatment. Moreover, EBR pretreatment also increased superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) activity, as well as ascorbic acid (AsA) and glutathione contents. These results suggested that EBR improved salt tolerance by enhancing osmotic adjustment and antioxidant defense systems in perennial ryegrass.
Differences in Sucrose Metabolism in Peach Fruit Stored at Chilling Stress versus Nonchilling Stress Temperatures
Authors: Yu Fang , Ni Zhiming , Shao Xingfeng , Yu Lina , Liu Hongxing , Xu Feng , Wang Hongfei
Published: February 2019

To explore differences in sucrose metabolism between peach fruit subjected to chilling stress (5 °C) and nonchilling stress (10 °C), sucrose concentration as well as the activities and gene expression levels for enzymes associated with sucrose metabolism were compared. Fruits stored at 5 °C accumulated higher concentrations of H2O2 and developed severe chilling injury (CI) compared with fruit kept at 10 °C. Activities and gene expression levels for enzymes related to sucrose metabolism, such as acid invertase (AI), neutral invertase (NI), sucrose synthase (SS), and sucrose phosphate synthase (SPS) were higher in fruit stored at 5 °C than at 10 °C throughout or late in storage. A sharp increase in net sucrose cleavage activity dramatically decreased sucrose concentration and increased reducing sugars at 5 °C. The sucrose concentration at 10 °C increased over the first 21 days and then declined slightly, and was higher than in fruit at 5 °C throughout storage. The increase in net sucrose cleavage activity at 5 °C is contrary to the expectation that biochemical reactions ordinarily proceed more rapidly with increasing temperature. We conclude that chilling stress stimulates the activities and transcription levels of enzymes involved in sucrose metabolism, resulting in increased sucrose cleavage.
Closing the Loop: Use of Biochar Produced from Tomato Crop Green waste as a Substrate for Soilless, Hydroponic Tomato Production
Authors: Dunlop Samuel J. , Arbestain Marta Camps , Bishop Peter A. , Wargent Jason J.
Published: February 2019

Greenhouse tomato (Lycopersicum esculentum Mill.) producers are urged to reduce their environmental footprint. Here, the suitability of biochar produced from tomato crop green waste as a substrate for soilless, hydroponic tomato production was evaluated. Substrates containing different combinations of biochar (BC) and pine (Pinus radiata D. Don) sawdust (SD) were produced (BC0-SD100, BC25-SD75, BC50-SD50, BC75-SD25, and BC100-SD0) and characterized. The effect of these substrates on tomato growth, yield, and fruit quality was studied. Most of the measured properties of substrates containing biochar were suited to use as a soilless substrate. The electrical conductivity (EC) of substrates containing biochar was initially high (>4.6 mS·cm−1), but was easily reduced to <0.5 mS·cm−1 by rinsing with water before use. The pH of substrates containing biochar was higher than is considered acceptable for tomato production (7.5–9.3) but did not significantly (P < 0.05) affect any plant growth, yield, and fruit quality indicators measured compared with those of plants grown in pine sawdust. The results support the concept of creating a closed loop system whereby biochar produced from tomato crop green waste is used as a substrate for soilless, hydroponic tomato production, providing a sustainable means to support the growth of high-value food crops.
Lack of Correspondence between Experimentally Determined Values of Vitamin E in Carrot (Daucus carota L.) and Those Reported in the USDA National Nutrient Database
Authors: Luby Claire H. , Vernon Rachael , Maeda Hiroshi A. , Goldman Irwin L.
Published: February 2019

Vitamin E compounds, known collectively as tocochromanols, are essential nutrients found in plant tissues. These compounds are present in fruits and vegetables at lower levels than in nuts and oils. However, since fruits and vegetables are frequently consumed in the diet, they represent important contributions to vitamin E intake. Knowledge of nutrient levels in fruits and vegetables is important in making dietary recommendations and in planning menus. The U.S. Department of Agriculture (USDA) National Nutrient Database (NNB) reports levels of vitamin E in carrot of 6.6 µg·g−1 on a fresh weight basis and similar levels of vitamin E for food products containing carrots, such as baby food and carrot juice. We collected data on four tocochromanol compounds using reverse-phase high-performance liquid chromatography (HPLC) with fluorescence detection on both fresh carrots and on commercially available food products containing carrots. Our data revealed that levels of vitamin E in fresh carrot and food products containing carrot were in the range of 0.007–0.12 µg·g−1 converted to a fresh weight basis. These levels were consistent with several published research studies for carrot, lower than several other published studies, and significantly lower than values reported in the NNB. Data from our studies show actual vitamin E values for this vegetable may be significantly lower than levels published in the NNB, but large discrepancies exist in the published reports for measurement of tocochromanol levels for this vegetable. Dietary guidance based on vitamin E values for carrot reported in the NNB could lead to inaccurate nutrient recommendations and should be clarified and standardized.
Effect of Pepper Types on Obtaining Spontaneous Doubled Haploid Plants via Anther Culture
Authors: Keleş Davut , Pınar Hasan , Ata Atilla , Taşkın Hatıra , Yıldız Serhat , Büyükalaca Saadet
Published: February 2019

The most successful technique used to obtain haploid plant in pepper is anther culture. The chromosome content of haploid plants can be doubled spontaneously or using colchicine. In this study, we compared the rate of spontaneous doubled haploidy of different pepper types. Seven charleston, six bell, eight capia, and seven green pepper genotypes were used as plant material. Murashige and Skoog (MS) nutrient medium with 4 mg·L−1 naphthaleneacetic acid (NAA), 0.5 mg·L−1 6-benzylaminopurine (BAP), 0.25% activated charcoal, 30 g·L−1 sucrose, and 15 mg·L−1 silver nitrate (AgNO3) was used. Ploidy levels of plants obtained through anther culture were detected using both flow cytometry and simple sequence repeats (SSR) markers. The results showed that different spontaneous doubled haploidy rates were obtained from different pepper types. The highest rate was observed in bell pepper type with 53.4% (mean of six genotypes) of haploid plants undergoing spontaneous chromosome doubling. This was followed by charleston and capia types with 31.9% and 30.4% doubling, respectively. Green pepper type gave the lowest spontaneous doubled haploidy rate with 22.2% doubling. The results obtained from this study will be useful both for future work on haploidy in pepper and for breeding programs.
Physiological and Antioxidant Parameters in Two Lycoris Species as Influenced by Water Deficit Stress
Authors: Xu Sheng , Jiang Mingmin , Fu Jiangyan , Liang Lijian , Xia Bing , Wang Ren
Published: February 2019

From a field experiment, the changes in morphophysiological characters and antioxidant enzyme activities were studied in two Lycoris species (Lycoris radiata and Lycoris aurea) subjected to 16 days of water deficit stress. With the increase of water deficit stress processing time, leaf relative water content (RWC), membrane stability index (MSI), net photosynthesis (Pn), stomatal conductance (gS), transpiration rate (E), and chlorophyll (Chl) content decreased in both studied species. The water use efficiency (WUE) showed an opposite tendency between the two species under water deficit stress, where WUE of L. aurea decreased moderately and WUE of L. aurea increased somehow. Intercellular CO2 concentration (Ci) in L. aurea and L. radiata decreased in respond to water deficit stress at early stages of stress treatment, then increased throughout the rest of the stress period, and reached levels higher than those in well-watered plants at the end of the treatment. In addition, there was a significant increment in soluble sugar content and proline accumulation under water deficit stress in both species, and L. radiata showed a much more accumulation. The activity of superoxide dismutase (SOD), guaiacol peroxidase (POD), and ascorbate peroxidase (APX) increased in both plants subjected to water deficit stress while declined as the stress time increased. In L. aurea, catalase (CAT) showed a sustained increment, but it responded later and after a transient increase declined again in L. radiata under water deficit stress. In conclusion, L. radiata was more tolerant to water deficit stress than L. aurea as evidenced by its relatively higher water status, higher levels of proline, soluble sugar and pigments, and stronger photoprotection. Moreover, relatively higher antioxidant enzyme activities and lower levels of thiobarbituric acid reactive substances (TBARS) in L. radiata were also associated with its better protection against water deficit stress-induced oxidative damage.
Micronutrient Availability from Steel Slag Amendment in Peatmoss Substrates
Authors: Altland James E. , Krause Charles , Locke James C. , Zellner Wendy L.
Published: February 2019

The objective of this research was to determine the suitability of a steel slag product for supplying micronutrients to container-grown floriculture crops. Geranium (Pelargonium ×hortorum L.H. Bailey ‘Maverick Red’) and tomato (Solanum lycopersicon L. ‘Megabite’) were grown in 11.4-cm containers with a substrate composed of 85 peatmoss : 15 perlite (v/v). A group of containers referred to as the commercial control (C-control) were amended with 4.8 kg·m−3 dolomitic lime and fertilized with a commercial complete fertilizer providing macro and micronutrients (Jack’s 20N–4.4P–16.6K–0.15Mg–0.02B–0.01Cu–0.1Fe–0.05Mn–0.01Mo–0.05Zn) at a concentration of 100 mg·L−1 nitrogen (N). Another group of containers, referred to as the micronutrient control (M-control), were amended with a commercial granular micronutrient package at 0.9 kg·m−3 and dolomitic lime at 4.8 kg·m−3. The M-controls were fertilized with 7.1 mm N (100 mg·L−1 N) with ammonium nitrate and 2 mm potassium phosphate. A final group of containers were amended with 1.2, 2.4, or 4.8 kg·m−3 of steel slag and fertilized with 3.6 mm ammonium nitrate and 2 mm potassium phosphate. Both control groups resulted in vigorous and saleable plants by the conclusion of the experiment. In both crops, chlorophyll levels, root ratings, and shoot dry mass were lower in all steel slag–amended plants compared with either control groups. In geranium, foliar nutrient concentrations suggest Cu and Zn were limiting whereas B and Zn were limiting in tomato. Based on the results of this research, steel slag does not provide sufficient micronutrients, most notably B, Cu, and Zn, to be the sole source of micronutrient fertilization in container-grown crops.
Development of Sequence-characterized Amplified Region Markers for the Identification of Grapevine Cultivars
Authors: Cho Kang Hee , Noh Jung Ho , Park Seo Jun , Kim Se Hee , Kim Dae-Hyun , Chun Jae An
Published: February 2019

Grapevine cultivars have traditionally been identified based on the morphological characteristics, but the identification of closely related cultivars has been difficult because of their similar pedigree backgrounds. In this study, we developed DNA markers for genetic fingerprinting in 37 grapevine cultivars, including 20 cultivars bred in Korea. A total of 180 randomly amplified polymorphic DNA (RAPD) markers were obtained using 30 different primers. The number of polymorphic bands ranged from three (OPG-08 and OPU-19) to nine (OPV-01 and UBC116), with an average of six. RAPD markers were used in cluster analysis performed with the unweighted pair-group method of arithmetic averages (UPGMA). The average similarity value was 0.69 and the dendrogram clustered the 37 grapevine cultivars into five clusters. The relationships among the grapevine cultivars were consistent with the known pedigrees of the cultivars. The 50 RAPD fragments selected were sequenced for the development of sequence-characterized amplified region (SCAR) markers. As a result, 16 of 50 fragments were successfully converted into SCAR markers. A single polymorphic band, the same size as the RAPD fragments or smaller, was amplified depending on the primer combinations in the 14 SCAR markers, and codominant polymorphisms were detected using the SCAR markers G119_412 and GB17_732. Among these markers, combination of 11 SCAR markers, GG05_281, G116_319, G146_365, G119_412, GW04_463, G169_515, G116_539, GV04_618, GV01_678, GG05_689, and GB17_732, provided sufficient polymorphisms to distinguish the grapevine cultivars investigated in this study. These newly developed markers could be a fast and reliable tool for identifying grapevine cultivars.
Effects of Pre- and Postharvest Calcium Treatments on Shelf Life and Postharvest Quality of Broccoli Microgreens
Authors: Kou Liping , Yang Tianbao , Liu Xianjin , Luo Yaguang
Published: February 2019

We reported previously that the preharvest treatment of broccoli microgreens with 10 mmol·L−1 calcium chloride (CaCl2) increased the yield and postharvest quality. The objective of this study was to investigate whether other calcium forms have the similar effect, in particular, after postharvest dip in calcium solution. Our results are as follows: 1) Preharvest spray without postharvest dip: Both 20 mmol·L−1 calcium lactate (Ca lactate) and calcium amino acid (Ca AA) chelate significantly improved broccoli microgreens quality and inhibited microbial populations as compared with the water-only control during storage at 5 °C for 21 days. However, they were less effective than 10 mmol·L−1 CaCl2. 2) Postharvest dip without preharvest spray: The microgreens sprayed with water-only control were dipped in 0, 25, 50, or 100 mmol·L−1 Ca lactate solution containing 100 μL·L−1 chlorine immediately after harvest. During storage at 5 °C for 14 days, 50 mmol·L−1 Ca lactate dip showed the highest overall quality and lowest tissue electrolyte leakage. 3) Preharvest spray and postharvest dip: Combined preharvest 10 mmol·L−1 CaCl2 spray and postharvest 50 mmol·L−1 Ca lactate dip resulted in better postharvest quality than individual pre- or postharvest calcium treatments. However, the preharvest 10 mmol·L−1 CaCl2 spray without postharvest dip displayed a best overall visual quality and longest storage life. Our data indicate that pre- and postharvest calcium treatments have positive effect on maintaining the microgreens quality and extending shelf life. However, current postharvest dip/spinning/drying method profoundly reduces the shelf life due to mechanical damages. Technologies to optimize microgreens wash are needed to provide ready-to-eat product. Alternatively, the wash step can be avoided when the microgreens are grown under controlled settings.
Grafting with an Interspecific Hybrid Squash Rootstock Accelerated Fruit Development and Impaired Fruit Quality of Galia Melon
Authors: Guan Wenjing , Zhao Xin , Huber Donald J.
Published: February 2019

Interspecific hybrid squash (Cucurbita maxima × Cucurbita moschata) is a well-known cucurbit rootstock for controlling soilborne diseases and improving abiotic stress tolerance. However, reduced fruit quality has been reported on certain melon (Cucumis melo) cultivars when grafted with squash rootstocks. In this study, a field experiment was designed to explore fruit development and quality attributes of galia melon ‘Arava’ by grafting with hybrid squash rootstock ‘Strong Tosa’. Grafted plants with ‘Strong Tosa’ showed delayed anthesis of female flowers by ≈8–9 days, but harvest dates were unaffected compared with non- and self-grafted ‘Arava’ plants. Early and total yields were not significantly different between grafted and nongrafted plants. Grafted plants with ‘Strong Tosa’ rootstock exhibited accelerated fruit development and greater vegetative growth. During the harvest period, ≈27% of grafted plants with ‘Strong Tosa’ wilted, which was determined as nonpathogenic. Grafting with ‘Strong Tosa’ rootstock resulted in reduced fruit total soluble solids (TSS) and consumer rated sensory properties.
A Vast Array of Beauty: The Accomplishments of the Father of American Ornamental Breeding, Luther Burbank
Authors: Anderson Neil O. , Olsen Richard T.
Published: February 2019

Luther Burbank (1849–1926) was a prolific ornamental plant breeder, who worked with 91 genera of ornamentals, from Abutilon to Zinnia, and released nearly 1000 cultivars to the industry. His innovative work included both herbaceous and woody plant materials as well as ornamental vegetables such as corn, tomatoes, and spineless cacti. His most popular ornamental release, the shasta daisy hybrids—first released in 1901, is still on the global market. This article focuses on Luther Burbank’s breeding techniques with ornamental plants and how both the germplasms that he developed and his methodologies used permeate modern flower breeding. Genera with the highest number of cultivars bred and released by Burbank include Amaryllis, Hippeastrum, and Crinum followed by Lilium, Hemerocallis, Watsonia, Papaver, Gladiolus, Dahlia, and Rosa. With Lilium, he pioneered breeding the North American native lily species, particularly those from the Pacific coastal region, producing the eponymous Lilium ×burbankii. Burbank’s breeding enterprise was designed to be self-sustaining based on profits from selling the entire product line of a new cultivar or crop only to wholesale firms, who then held exclusives for propagation and selling, although financial hardships necessitated selling retail occasionally. Entire lots of selected seedlings were sold to the highest bidder with Burbank setting the price in his annual catalogs such as the Burbank Hybrid Lilies lot for U.S. $250,000 or some of the “very handsome, hardy ones” for U.S. $250 to U.S. $10,000 each. Other flower cultivars also commanded high prices such as seedling Giant Amaryllis that sold for U.S. $1.55/bulb in 1909. Cacti were another area of emphasis (he released more than 63 cultivars) from the spineless fruiting and forage types (Opuntia ficus-indica, O. tuna, O. vulgaris) to flowering ornamentals such as O. basilaris, Cereus chilensis, and Echinopsis mulleri. Interest in cacti during 1909–15 rivaled the Dutch Tulip mania with exorbitant fees for a single “slab” of a cultivar, speculative investments, controversy with noted cacti specialists (particularly David Griffiths), and lawsuits by The Burbank Company. Although most cultivars have been lost, Burbank’s reputation as the Father of American Ornamental Breeding remains admirable from critics and devotees alike.
21st Century Approach to Improving Burbank’s ‘Stoneless’ Plum
Authors: Callahan Ann , Dardick Chris , Tosetti Roberta , Lalli Donna , Scorza Ralph
Published: February 2019

The theme running through many of Luther Burbank’s breeding programs was to make plants more tailored to human uses. Mr. Burbank thought that the stone in plum fruits was unessential to a tree that was propagated vegetatively, so he chose stoneless plums as a breeding goal. He made two releases, ‘Miracle’ in 1903 and his final and almost perfect ‘Conquest’ in 1916, which he considered one of his best accomplishments in plum breeding. ‘Conquest’ had only a grain of stone and flavor and size comparable to the best French types of the time but was not commercially successful. In view of the current desire for convenience food such as seedless fruit (citrus, grapes, watermelon) and advanced knowledge of genetics and breeding technologies, we have taken up where Mr. Burbank left off in the production of a better than “almost perfect” stoneless plum. We began by locating what were most likely remnants from Mr. Burbank’s breeding program and we are now using 21st century technology to achieve a completely stoneless, high-quality plum fruit. These technologies include molecular markers, genetic engineering, and accelerated breeding cycles (FasTrack). Initial experiments had characterized the stoneless trait as a decrease in the number of endocarp cells that form the stone. We defined the time critical to the formation of endocarp by analyzing gene expression of a number of transcription factors involved with determining endocarp cells. We identified genes that were expressed differently during this period between normal stone cultivars and one of the stoneless cultivars. In addition, we targeted genes for genetic engineering to reduce the lignification in endocarp and to reduce or convert endocarp cells to non-lignifying cells. A system, FasTrack, using a flowering gene from poplar, has been incorporated to reduce the juvenility period and eliminate the seasonal aspect of fruiting to see the results of the breeding as well as the genetic engineering approach much faster. The combination of these approaches is now in place to attempt to improve on Mr. Burbank’s stoneless plum.
Effects of Living Mulch and Fertilizer on the Performance of Broccoli in Plasticulture
Authors: Warren Nicholas D. , Smith Richard G. , Sideman Rebecca G.
Published: February 2019

Living mulch systems allow cover crops to be grown during periods of cash crop production, thereby extending the duration of cover crop growth and associated beneficial agroecosystem services. However, living mulches may also result in agroecosystem disservices such as reduced cash crop yields if the living mulch competes with the crop for limiting resources. We examined whether the effects of an Italian ryegrass [Lolium multiflorum (Lam.) Husnot]–white clover (Trifolium repens L., cv. New Zealand) living mulch on broccoli (Brassica oleracea L. var. italica) yield and yield components were dependent on fertilizer rate in field experiments conducted in Durham, NH, in 2011 (Expt. 1) and 2012 (Expt. 2). Drip-irrigated broccoli was grown under a range of organic fertilizer application rates in beds covered with plastic, with and without a living mulch growing in the uncovered, interbed space. Broccoli yields were similar in the living mulch and bare soil controls under the highest rates of fertilizer application in Expt. 1. In Expt. 2, living mulch reduced broccoli yields from 28% to 63%, depending on fertilizer rate. Differences in leaf SPAD values suggest that yield reductions were attributable, in part, to competition for nitrogen; however, other factors likely played a role in determining living mulch effects. Despite yield reductions, the living mulch reduced the prevalence of hollow stem in broccoli in Expt. 1. Organic fertilizer may have inconsistent effects on broccoli yields in living mulch systems.
Liquid Corn and Fish Fertilizers Are Good Options for Fertigation in Blackberry Cultivars Grown in an Organic Production System
Authors: Fernandez-Salvador Javier , Strik Bernadine C. , Bryla David R.
Published: February 2019

The impact of organic fertilizer source on the growth, fruit quality, and yield of blackberry (Rubus L. subgenus Rubus Watson) cultivars (Marion and Black Diamond) grown in a machine-harvested, organic production system for the processed market was evaluated from 2011 to 2013. The planting was established in Spring 2010 using approved practices for organic production and was certified in 2012. Plants were irrigated using a dripline under a woven polyethylene groundcover (weed mat) installed for weed management. Two sources of liquid fertilizer were evaluated: 1) a corn steep liquor and fish waste digestion blend (“corn”; 2.5N–1.1P–1.2K); and 2) a fish solubles and molasses blend (“fish”; 4N–0P–1.7K). Fertilizers were applied by fertigation through the drip system at rates of 56 kg·ha−1 nitrogen (N) per year in 2011–12 and 90 kg·ha−1 N in 2013. The impact of fertigation on drip system performance was evaluated with two maintenance options, “flushing” and “no flushing” of the driplines. Total yield differed among years, whereas fruit soluble solids concentration and firmness as well as floricane biomass at pruning showed a year × cultivar interaction. ‘Black Diamond’ had greater total yield and average fruit weight than ‘Marion’, but produced a greater proportion unmarketable fruit. There was no effect of fertilizer source on yield, fruit quality, primocane length, or primocanes/plant in any year with the exception of fruit weight, which was greater with corn than with fish. ‘Marion’ had a greater floricane biomass when fertilized with fish than with corn. Soil nutrients were within the recommended range, except for boron (B), which was below recommended levels. Only soil nitrate-N was affected by fertilizer source, which was greater in ‘Marion’ than in ‘Black Diamond’ when fertilized with fish. Primocane leaf tissue nutrient concentrations were within recommended levels for all nutrients, except for calcium (Ca) and B, which were below recommended standards in both cultivars. Primocane leaf potassium (K) and zinc (Zn) concentrations were greater with fish than with corn. There was no fertilizer source or maintenance effect on emitter flow rate of the drip system in either year. However, flow rates decreased an average of 4.5% in the first year and 19% in the second year. Overall, there were no differences between the fertilizers on plant growth, yield, or fruit quality, and both fertilizers were suitable for planting establishment.
Trailing Blackberry Genotypes Differ in Yield and Postharvest Fruit Quality during Establishment in an Organic Production System
Authors: Fernandez-Salvador Javier , Strik Bernadine C. , Zhao Yanyun , Finn Chad E.
Published: February 2019

Four blackberry (Rubus L. subgenus Rubus Watson) cultivars (‘Obsidian’, ‘Black Diamond’, ‘Metolius’, ‘Onyx’) and two advanced selections (ORUS 1939-4 and ORUS 2635-1) were evaluated during the establishment years of an organic production system for fresh market. The planting was established in Spring 2010 using approved practices for organic production and was certified organic in 2012, the first fruiting year. Plants were irrigated using a dripline under a woven polyethylene groundcover (weed mat) installed for weed management. Liquid fertilizers injected through the drip system were used at rates of 56 kg·ha−1 total nitrogen (N) in 2011–12 and 90 kg·ha−1 total N in 2013. Genotypes differed in the level of nutrients measured in primocane leaves. Tissue phosphorus (P), potassium (K), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) concentrations were within the recommended standards, but tissue calcium (Ca), magnesium (Mg), and boron (B) were deficient in some or all genotypes. Although two cultivars and both advanced selections responded well in terms of plant growth and yield to the organic production system used, yields in ‘Onyx’ and ‘Metolius’ were considered low for commercial production. In contrast, the higher yielding ‘Obsidian’ and ORUS-2635-1 appeared to be the best suited for organic fresh market production as a result of larger fruit size, greater fruit firmness, higher sugar-to-acid ratios, lower post-harvest percent moisture loss in ORUS-2635-1, and the longest number of marketable storage days at 5 °C in ‘Obsidian’.
Evaluation of Annual Bedding Plants for Resistance to White Mold
Authors: Grabowski Michelle A. , Malvick Dean K.
Published: February 2019

White mold, caused by the necrotrophic fungus Sclerotinia sclerotiorum (Lib.) de Bary, causes stem rot, crown rot, wilt, and death of many common herbaceous ornamental plants. Relatively little research has been done on management of white mold and resistance to this disease in ornamental crops. Plant varieties from four genera of widely available annual bedding plants with no reported history of white mold susceptibility were evaluated for potential resistance to S. sclerotiorum. All plants were inoculated with three isolates of S. sclerotiorum and evaluated for disease severity in a controlled environment and under field conditions. Portulaca grandiflora Hook. ‘Sundial Scarlet’, P. grandiflora ‘Sundial White’, Pentas lanceolata Forssk. ‘Graffiti Pink’, and Scaevola aemula R. Br. ‘Whirlwind White’ were highly susceptible to white mold in the controlled environment but had significantly lower disease incidence and severity than Zinnia elegans ×angustifolia ‘Profusion White’, the susceptible control, under field conditions. Impatiens hawkeri W. Bull. ‘Sonic Red’, I. hawkeri ‘Sonic Amethyst’, I. hawkeri ‘Sonic White’, I. walleriana Hook. f. ‘Blitz 3000 Red’, I. walleriana ‘Blitz 3000 White’, and I. walleriana ‘Blitz 3000 Rose’ displayed abscission of diseased plant tissue as an unusual resistance response. Plants from all four genera that were evaluated became infected with S. sclerotiorum to a lesser extent than susceptible controls under field conditions and could be used as part of an integrated disease management program for white mold in ornamental plantings.
Glyphosate Tolerance of Two Perennial Ryegrass Cultivars from Fall Applications and at Seedling Growth Stages
Authors: Baldwin Christian M. , Blythe Eugene K. , Brede A. Douglas , Mayer Jami J. , Golembiewski R.
Published: February 2019

The use of glyphosate-tolerant perennial ryegrass (Lolium perenne L.) (PRG) cultivars JS501 and Replay provides turfgrass managers a unique option for annual bluegrass (Poa annua L.) (ABG) control. Both cultivars can tolerate a maximum glyphosate rate of 0.81 kg·ha−1 acid equivalent (a.e.) after establishment under optimal growing temperatures (16 to 24 °C). However, tolerance to applications made immediately after germination and during low air temperatures has received limited investigation. Therefore, objectives of this research were to determine the seedling tolerance and low-temperature response after a fall season glyphosate application to both cultivars. Field trials were conducted in Idaho and Oregon. For the fall application response trial in Idaho, glyphosate was applied at 0, 0.15, 0.29, 0.58, 1.16, 1.74, 2.32, and 3.48 kg·ha−1 a.e. In Oregon, glyphosate was applied at 0, 0.15, 0.29, 0.44, 0.58, 1.16, and 3.48 kg·ha−1 a.e. At both sites, applications were made between late September and early October. To determine seedling tolerance, both cultivars were sprayed with glyphosate at the one-leaf stage (LS), two LS, three LS, or four LS at rates of 0, 0.15, 0.29, and 0.58 kg·ha−1 a.e. Across all trials, ratings included PRG color, cover, and injury. At both trial locations, regression analysis revealed a rate of ≈0.27 kg·ha−1 a.e. was required to cause 20% leaf firing in the fall application response trial. In the seedling tolerance trial, glyphosate applied at 0.58 kg·ha−1 a.e. at the one LS, two LS, and three LS had color ratings 8.0 or greater; however, color ratings dropped to 4.6 when an application was made at the four LS. Based on the environmental conditions of each trial, results suggest glyphosate applications greater than 0.27 kg·ha−1 a.e. as minimum air temperatures approach 0 °C should be avoided. Also, applications should be avoided at the three to four LS if the application rate is greater than 0.29 kg·ha−1 a.e.
Spur Fruit Set Is Negatively Related with Current-year Spur Leaf Area in Almond
Authors: Tombesi Sergio , Lampinen Bruce D. , Metcalf Samuel , DeJong Theodore M.
Published: February 2019

Almond spurs are known to be the primary bearing unit in almond tree and are subject to alternate bearing. Fruits are a strong sink in bearing spurs and can influence spur leaf growth. At the same time the percent of flowers that set fruit on a spur (spur relative fruit set) could be influenced by the competition among multiple flowers/fruits borne on the same spur as well as by limited leaf area on the same spur. The aim of the present work was to investigate the relationship between current-year spur leaf area and spur absolute and relative fruit set. Approximately 2400 spurs were tagged and followed over 6 years and data concerning spur leaf area, number of flowers per spur, and number of fruits per spur were collected. Spur leaf area was reduced in fruiting spurs in comparison with non-fruiting spurs according to the number of fruits borne by each spur. This phenomenon contributes to spur alternate bearing because spur flowering and survival in the next year are a function of the leaf area in the current year. Relative fruit set in almond appears to be negatively associated with current-year spur leaf area. Competition among fruits on the same spur did not appear to influence spur relative fruit set.
Susceptibility to Xylella fastidiosa in a First-generation Hybrid from a non-traditional Peach–Almond Cross
Authors: Rogers Elizabeth E. , Ledbetter Craig A.
Published: February 2019

To facilitate development of Prunus L. rootstocks with desirable agronomic traits, domesticated peach (Prunus persica) and almond (P. dulcis) were crossed with wild almond relatives. This work reports that a hybrid from a P. webbii × P. persica cv. Harrow Blood cross is susceptible to almond leaf scorch disease (ALSD). ALSD is caused by the fastidious, xylem-limited bacterium Xylella fastidiosa. The P. webbii × ‘Harrow Blood’ hybrid, along with its parents, was inoculated with two ALSD-inducing strains (X. fastidiosa subsp. fastidiosa strain M23 and subsp. multiplex strain Dixon). Both X. fastidiosa strains grew to high titer in the susceptible P. webbii parent and in the interspecific hybrid; defoliation was also observed. As expected, ‘Harrow Blood’ did not exhibit defoliation symptoms or support growth of X. fastidiosa. This result contrasts with earlier work demonstrating that a P. persica × P. dulcis hybrid is not a suitable host for X. fastidiosa subsp. fastidiosa M23. It appears that the genetic basis of resistance/susceptibility differs between a P. persica × P. dulcis cross and the P. webbii × P. persica cross reported here. Understanding the degree of susceptibility to X. fastidiosa in complex hybrids of subgenus Amygdalus should be an important part of rootstock development.
Physiological, Morphological, and Energy-use Efficiency Comparisons of LED and HPS Supplemental Lighting for Cucumber Transplant Production
Authors: Hernández Ricardo , Kubota Chieri
Published: February 2019

To increase the available photosynthetic photon flux (PPF) for plant growth, greenhouse growers sometimes use electric lighting to supplement solar light. The conventional lighting technology used to increase PPF in the greenhouse is high-pressure sodium lamps (HPS). A potential alternative to HPS is high-intensity light-emitting diodes (LEDs). The objective of this study is to compare supplemental LED lighting with supplemental HPS lighting in terms of plant growth and morphology as well as discuss the energy use efficiencies of the fixtures. There were three light treatments: 1) blue LED (peak wavelength 443 nm); 2) red LED (peak wavelength 633 nm); and 3) HPS, to provide 3.7 ± 0.2 mol·m−2·d−1 (background solar radiation of 6.3 ± 0.9 mol·m−2·d−1). Cucumber (Cucumis sativus) plants at the transplanting stage (26 to 37 days) under HPS had 28% greater dry mass than did plants under the LED treatments. This can be attributed to the higher leaf temperature under the HPS treatment. No differences were observed in growth parameters (dry mass, fresh weight, or number of leaves) between the blue and red LED treatments. Plants under the blue LED treatment had greater net photosynthetic rate and stomatal conductance (gS) than those under the red LED and HPS treatments. Plants under the blue LED and HPS treatments had 46% and 61% greater hypocotyl length than those under the red LED, respectively. The fixture PPF efficiencies used in the experiment were 1.9, 1.7, and 1.64 μmol·J−1 for the blue LED, red LED, and HPS treatments, respectively; however, the fixture growing efficiency (g·kWh−1) of HPS was 6% and 17% greater than the blue LED and red LED treatment, respectively. In summary, supplemental red LED produced desirable plant compactness and HPS had greater fixture growing efficiency than LEDs.
Influence of Temperature, Low Nutrient Supply, and Soil Composition on Germination and the Growth of Sea Kale (Crambe maritima L.)
Authors: Christensen Jonas , Lauridsen Uffe Bjerre , Andreasen Christian , Lütken Henrik
Published: February 2019

Sea kale (Crambe maritima L.) is a wild edible plant with forgotten and undiscovered potential as a field vegetable. Its natural habitat is gravel beaches in northern Europe and the Black Sea. Three experiments were conducted to find the effect of temperature on seed germination and to determine plant growth response to organic fertilizer and soil types. Germination rates were estimated at three temperatures. Plant growth responses were conducted with application of two fertilizer concentrations [15 and 30 kg plant-available nitrogen (PAN)/ha] and by using four distinct soil types. Seeds sown at 20 and 15 °C reached a significantly greater germination rate after 32 days (48.0% and 40.4%, respectively) than seeds sown at 10 °C (16.6%). The number of days when 50% of the seeds that germinated during the experiment had germinated (T50) were 12.0, 11.8, and 16.8 days for 20, 15, and 10 °C, respectively. Application of 15 or 30 kg·ha−1 PAN did not result in any significant differences in plant size or biomass within 2 months of growth in sandy loam, but substantial plant heterogeneity was observed. Soil composition had a significant effect (P ≤ 0.05) on plant biomass. Plants grown in fine or loamy sand had the greatest growth and biomass. Sea kale seems to have a potential to become a field vegetable, because it grows well on other soil types than gravel. However, domestication processes of the species are required to obtain homogenous plants for future propagation.