Interest in native landscape plants to support pollinators has increased. Most native plants sold by nurseries are cultivars, and some consumer and conservation groups question the suitability of native cultivars to support pollinators. In 2017 and 2018, insect pollinator visitation was quantified for six native shrub species and one or more cultivars of each species (Aronia melanocarpa, A. melanocarpa ‘UCONNAM012’ Ground Hog®, A. melanocarpa ‘UCONNAM165’ Low Scape Mound®, Clethra alnifolia, C. alnifolia ‘Hummingbird’, C. alnifolia ‘Ruby Spice’, Dasiphora fruticosa, D. fruticosa ‘Goldfinger’, D. fruticosa ‘Pink Beauty’, Hydrangea arborescens, H. arborescens ‘Annabelle’, Kalmia latifolia, K. latifolia ‘Sarah’, Physocarpus opulifolius, and P. opulifolius ‘Monlo’ Diabolo®). Insects were identified into 12 categories (Apis mellifera, Bombus spp., Andrenidae, Halictidae, Megachilidae, other bees, Lepidoptera, Syrphidae, other flies, wasps, Coleoptera, and other insects). The number of inflorescences and insect visitation was similar for C. alnifolia and its cultivars, and the compact cultivar Hummingbird had the greatest floral density. A. melanocarpa had more total visitors of Andrenidae than both of its compact cultivars because it was larger and produced more inflorescences. Compact Aronia cultivars and the straight species were mostly similar for Andrenidae visitation when compared on a per-inflorescence basis. D. fruticosa had more visitors of Bombus spp. and Megachilidae than both of its cultivars. These insects may have been less attracted to ‘Pink Beauty’ because of its pink flower color and ‘Goldfinger’ because of its wider flowers, which result from it being a tetraploid. H. arborescens ‘Annabelle’ had one-third the number of Bombus spp. visitors as H. arborescens because ‘Annabelle’ produces >50% fewer fertile florets. P. opulifolius ‘Monlo’ attracted more syrphids than P. opulifolius possibly because flowers contrasted more strongly with the reddish purple foliage of ‘Monlo’ than with the green foliage of the straight species. Insect visitation was similar for K. latifolia and K. latifolia ‘Sarah’. Based on this work, we determined that native shrub cultivars are not universally less or more attractive to pollinators and must be evaluated on a case-by-case basis.
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Jacob G. Ricker, Jessica D. Lubell and Mark H. Brand
Seth D. Wannemuehler, James J. Luby, Chengyan Yue, David S. Bedford, R. Karina Gallardo and Vicki A. McCracken
Incorporating DNA-informed breeding techniques can improve selection efficiency for desired traits as compared with conventional breeding methods that do not use DNA-informed techniques. Incorporation of DNA technologies requires additional costs associated with reagents, equipment, and labor. To elucidate the cost-effectiveness of DNA-informed breeding in perennial crops with multiple years per generation, we conducted a cost–benefit analysis examining incorporation of marker-assisted selection (MAS), a type of DNA-informed breeding, applied to an apple breeding program. Annual operational costs for a midwest apple breeding program were used to develop a simulation with inputs including itemized costs and per unit costs for procedures at each breeding program stage. Simulations compared costs of MAS breeding techniques to conventional breeding methods to identify the break-even point (BEP) where cost-savings associated with MAS equals the accrued additional costs. Additional sensitivity analyses were conducted to examine changes in laboratory costs, seedling maintenance costs, and seedling evaluation costs. We found the BEP for this program occurs when MAS results in a removal rate of 13.18%, and changes to other costs (i.e., maintenance costs) result in a smaller percent decrease to the overall program budget. Our findings are useful to perennial crop breeding programs in which managers are considering incorporating DNA-informed breeding techniques.
Satoru Motoki, Tianli Tang, Takumi Taguchi, Ayaka Kato, Hiromi Ikeura and Tomoo Maeda
Asparagus is a popular vegetable rich in healthy functional components. Asparagus spears are known to contain a large amount of rutin, which has been found to possess anti-inflammatory, antitumor, and antibacterial/viral properties, and protodioscin, which is an antitumor substance and present in the bottom parts (8 cm from the cut end). However, the process of its production leaves fern in the aboveground parts and roots in the underground parts as significant amounts of nonusable parts, and this issue should be solved. This study was conducted to examine the distributions of rutin and protodioscin, representative functional components in different parts of asparagus. The results suggested that large amounts of rutin were noted in the cladophylls and storage roots (brown and epidermis), and the protodioscin content was high in the buds, the soil-covered section of the spear, and the rhizome. A significant amount of rutin was detected in the aboveground parts, which is consistent with the results of previous studies, but it was also found in the storage roots. The largest amount of protodioscin was found in the buds, as well as in young fruits and seeds of the aboveground parts. Injury by continuously cropping asparagus may be associated with high rutin content in the storage roots of asparagus.
Xinjing Qu, Hui Wang, Ming Chen, Jiao Liao, Jun Yuan and Genhua Niu
Oil tea (Camellia oleifera) is an important edible oil tree. However, its growth and yield are strongly limited by drought. This study investigated the physiological and metabolic responses of two common oil tea cultivars, Huajin and Changlin53, to moderate and severe drought stress. Based on the photosynthetic and physiological indices, ‘Changlin53’ may be more tolerant to drought than ‘Huajin’. A total of 41 key metabolites induced by drought stress, including 12 amino acids, 12 organic acids, 10 carbohydrates, 3 fatty acids, and 4 phenols, have been identified by liquid chromatography-mass spectrometry. Under moderate drought stress, the contents of carbohydrates, amino acids, and some organic acids in ‘Changlin53’ were significantly increased; however, under severe drought stress, the contents of soluble sugars were decreased and the synthesis ability of amino acids and organic acids were enhanced. The glutamic acid–mediated proline biosynthesis pathway and salicylic acid synthesis were continuously upregulated in ‘Changlin53’ under moderate and severe drought stress, which could regulate osmotic pressure and maintain intracellular environmental stability. Under moderate drought stress, the contents of monosaccharides, amino acids, and organic acids increased in ‘Huajin’ leaves. Furthermore, the shikimic acid–mediated secondary metabolite synthesis pathway was weakened. More secondary metabolites were used to increase glycolysis and tricarboxylic acid cycle to accelerate energy production and to enhance the glutamic acid–mediated proline biosynthesis pathway, which are necessary to increase osmotic regulation. Under severe drought stress, the contents of carbohydrates, organic acids, and some amino acids were significantly decreased in ‘Huajin’ leaves, indicating serious damage. These results deepened our understanding of the mechanisms involved in oil tea drought tolerance, which will help improve water management of oil tea seedlings.
Alefsi David Sánchez-Reinoso, Gustavo Adolfo Ligarreto-Moreno and Hermann Restrepo-Díaz
Bean crops can be displaced to marginal areas or face abiotic stresses such as water deficit. Physiological responses allow the identification of tolerant genotypes and lead to more precise breeding strategies. The objective of this research was to evaluate the physiological (leaf gas exchange properties, leaf water content, and leaf thickness) and biochemical [proline and malondialdehyde (MDA)] responses of five common bush bean (Phaseolus vulgaris L.) cultivars (ICA-Cerinza, ICA-Bachue, NUA35, Bianca, and Bacatá) under a water shortage period by irrigation suspension (15 days) at two different phenological stages [vegetative: 40–55 days after seed emergence (DAE) or reproductive: (50–65 DAE)]. A completely randomized block design was carried out with a factorial arrangement (the phenological stage as the main factor and the cultivars as the secondary factor) for a total of 10 treatments with four repetitions per treatment. Leaf photosynthesis (P n) showed equal photosynthesis values in control plants of all cultivars (≈20 μmol·m−2·s−1). The water deficit period reduced P n close to 55% (≈12 μmol·m−2·s−1) at both, vegetative, or reproductive stage in all cases. Similar results were also observed on leaf thickness, with a reduction of ≈10% in water-stressed plants at either vegetative or reproductive stage in all evaluated cultivars. A higher MDA and proline production were observed in plants affected by a 15-day water deficit period, mainly at the vegetative stage. The obtained results suggest that the vegetative stage presented a more negative impact on the evaluated physiological variables in most of the cultivars used. Cultivar Bachue showed lower gas exchange properties affectation and higher proline content, which may indicate that this cultivar can be tolerant to water deficit stress conditions. This study allows suggesting that proline and MDA estimation are simple, fast, and low-cost techniques to screen cultivars to obtain more precise breeding selection in common bean. Finally, common bean cultivar selection through the use of biochemical markers can be complemented by the estimation of leaf gas exchange parameters at different phenological stages.
Lu Zhang, Robert Howard Beede, Gary Banuelos, Christopher M. Wallis and Louise Ferguson
Springtime flail mowing of row middles for weed control in California pistachio (Pistacia vera L.) orchards blows dust into the leafless canopy if it occurs during bloom. The effect of dust on pistachio pollination and fruit set is unknown. Rachises were bagged prebloom and hand pollinated with pollen and dust mixtures at 1:0, 1:1, 1:4, 1:16, and 0:1 volume/volume ratios on five successive days. The 2016 and 2017 trials demonstrated that the inflorescences treated with a high pollen:dust ratio (0:1, 1:4, and 1:16) had significantly lower split nut rates (commercially less profitable) compared with low dust ratio tests (1:0 and 1:1). Our results also showed that dust damaged both pollen viability and stigma quality, particularly if contaminated with herbicide residues (GlyStar® Plus and Treevix®). Decreased yield was a function of decreased fruit set; increased embryo abortion, parthenocarpy, or both; and a lower split nut percentage. The GA3 content in flowers of both the pollen and dust treatments was significantly higher than that in nonpollinated flowers, suggesting dust stimulated parthenocarpy, resulting in empty nutshells, “blanks” at harvest.
Shengrui Yao, Robert Heyduck and Steven Guldan
Jujube (Ziziphus jujuba Mill.), also called chinese date, cultivars have not been formally trialed in the United States after the 1950s. Currently, there are five to six commercially available jujube cultivars, with ‘Li’ as the dominant one. Both growers and consumers demand a wider range of cultivars to extend the maturation season and for different uses. We tested jujube cultivars at three locations in New Mexico [U.S. Department of Agriculture (USDA) hardiness zones 6a, 7a, and 8a] to assess their adaption and performance. These are early performance results for fresh eating cultivars. Jujubes were precocious; 50% to 95% of trees produced during their planting year, depending on cultivar and location. The average yield per tree for trees in their second to fourth year after planting were 409 g, 4795 g, and 5318 g at Alcalde; and 456 g, 3098 g, and 5926 g at Los Lunas, respectively. The yields varied by cultivar and location. ‘Kongfucui’ (‘KFC’) was the most productive cultivar at Alcalde and Los Lunas in both 2017 and 2018, followed by ‘Daguazao’, ‘Gaga’, ‘Honeyjar’, Maya’, ‘Redland’, and ‘Sugarcane’. ‘GA866’, ‘Alcalde #1’, ‘Zaocuiwang’, and ‘Sandia’ had the lowest yields among the 15 cultivars tested. ‘Alcalde #1’ was the earliest to mature with large fruit, suitable for marginal regions with short growing seasons, whereas ‘Sandia’ had the best fruit quality among all cultivars tested, suitable for commercial growers and home gardeners. ‘Maya’, ‘Gaga’, ‘Honeyjar’, and ‘Russian 2’ were very productive, early-midseason cultivars with small fruit but excellent fruit quality—a perfect fit for the home gardener market. ‘Li’, ‘Daguazao’, ‘Redland’, and ‘Shanxi Li’ were productive with large fruit. Cultivars grew faster and produced higher yields, larger fruit, and higher soluble solids at more southerly locations. This article discusses cultivars’ early performance up to the fourth year after planting. This is the first jujube cultivar trial report in the United States since the 1950s.
Xia Chun-hua and Chen Jian-hua
Anthurium andraeanum Lind. is an economically important potted and fresh-cut flower species. However, reduced anthocyanin content under shaded cultivation impacts the color of the spathe, which has negative implications for the marketability of A. andraeanum. Thus, the present study evaluates the use of oyster shell supplementation to the cultivation medium for improving anthocyanin content. Appropriate calcium (Ca) can improve the activity of phenylalanine ammonia lyase (PAL), and PAL activity is positively correlated with anthocyanin content; nitrogen (N) and phosphorus (P) nutrients are closely related to anthocyanin synthesis. N and P nutrients and Ca can alleviate the color symptoms of A. andraeanum when anthocyanin content decreases under weak light (under 220 μmol·m−2·s−1). Microdissolution of calcium carbonate, the main component of oyster shell, can provide better exogenous Ca and adsorb slow-release N and P. Selecting appropriate oyster shell fragments will be the key to A. andraeanum experimental cultivation under low light conditions. Using regression models and response surface methodology (RSM), the relationships between oyster shell fragments and anthocyanin content are promulgated. The main findings indicated that the Ca released from 286-mg oyster shell fragments at pH 5.5 significantly increased the activity of PAL in the pedicel under weak light within 8 hours. At pH 5.9, 375-mg oyster shell fragments could significantly adsorb N and P nutrients within 4 to 14 hours. In conclusion, 286 to 375 mg oyster shell fragments at pH 5.5 to 5.9 could stabilize slow-release fertilizer source and significantly increase anthocyanin content in A. andraeanum spathe.
Richard P. Marini, James R. Schupp, Tara Auxt Baugher and Robert Crassweller
In three experiments, diameters of apples representing 7% to 30% of the fruit on a tree were measured at ≈60 days after full bloom. Using previously published regression equations, the early-season fruit diameter values were used to estimate apple fruit weight at harvest (FWH). At harvest, all fruit on sample trees were weighed and the distributions of estimated FWH for fruit measured early in the season were compared with distributions of the actual FWH for whole trees. Actual FWH was normally distributed for only one of the three experiments. Although the estimated mean FWH averaged for the 10 trees was within 9% of the actual mean FWH for all three experiments, the distribution of estimated FWH differed significantly from the actual distribution for all three experiments. All fruit were then assigned to appropriate commercial fruit sizes or box counts (number of fruit/19.05 kg). Fruit size tended to peak on the same four box counts for the estimated and actual populations, but the estimated populations had too few fruits in the small- and large-size box counts. Using early-season estimates of FWH, commercial apple growers and packers can predict fairly accurately the percentage of the crop that will fall into the peak box counts, but a more accurate early-season estimate of the fruit size distribution will likely require measuring 50% of the fruit on a tree.
Sharon M. Tusiime, Gail R. Nonnecke, Dorothy M. Masinde and Helen H. Jensen
Tomato cultivars (Heinz 1370, MT 56, and Nuru F1), fungicide application (±), staking (±), and mulching (±) were tested for their effect on yield, disease severity, and gross margin in tomato production in the Kamuli District of Uganda. Treatments were arranged in a randomized complete block design with a factorial and split-plot arrangement in field plots in two growing seasons during 2013. Total and marketable fruit number, marketable fruit weight, gross margin, and disease severity, assessed using the area under disease progress curve, were measured. Disease-resistant and open-pollinated ‘MT 56’ in combination with fungicide application and soil mulch provided the highest marketable fruit number and marketable fruit weight and had a positive gross margin in the first growing season. A combination of ‘MT 56’ and treatments without applying fungicide and soil mulch resulted in the only positive gross margin in season two. Application of fungicides reduced disease severity (early blight, Alternaria solani Sorauer) for all cultivars in season one and for ‘Heinz 1370’ and ‘Nuru F1’ in season two, but did not affect disease severity for ‘MT 56’ in the second season. Using soil mulch reduced the severity of early blight disease, but decreased the gross margin when purchased. Staking did not affect yield, disease severity of plants, and decreased the gross margin. Cultivar MT 56 had the highest gross margin and marketable fruit and least disease severity, and seeds should be made available to small-landholder tomato farmers in Uganda to enhance their sustainable livelihoods.