Browse

You are looking at 1 - 10 of 29,673 items for

  • Refine by Access: All x
Clear All
Open access

Andrey Vega-Alfaro, Carlos Ramírez-Vargas, Germán Chávez, Fernando Lacayo, Paul C. Bethke, and James Nienhuis

The production of sweet peppers (Capsicum annuum) is often constrained in tropical environments by susceptibility to persistent soil-borne diseases, including bacterial wilt (Ralstonia solanacearum). However, the production of sweet peppers in high tunnels using sterile soilless media irrigated with nutrient solution offers the potential to reduce the incidence of bacterial wilt. An additional strategy for disease management is the use of sweet pepper scions grafted onto rootstocks that are resistant to soil-borne pathogens. Two sweet pepper cultivars grown extensively in the tropics, Nathalie and 4212, were used as scions and grafted onto the habanero pepper cultivar Habanero TEC (Capsicum chinense) and the aji pepper cultivar Baccatum TEC (Capsicum baccatum). Two cultivars related to the two rootstocks were prescreened for susceptibility to two virulent strains of bacterial wilt. Graft combinations were grown in two environments, a high tunnel with automatic nutrient solution irrigation of containers filled with sterile coconut fiber and an open field with known high levels of bacterial wilt inoculum. Self-grafted and nongrafted plants of scions were included as checks. The disease susceptibility screening showed that the area under the disease progress curve was consistently low for ‘Habanero TEC’ and ‘Baccatum TEC’ when inoculated with two virulent strains of bacterial wilt, suggesting that habanero pepper cultivars and, to a lesser degree, aji pepper cultivars may be useful as rootstocks in soils with bacterial wilt inoculum. Significant increases in yield, fruit number, and reduced time to flowering were observed in the high tunnel compared with the open-field environment. Individual fruit weight was reduced in the high tunnel compared with the field. Yield, fruit number, fruit weight, and time to flowering were consistent between scions regardless of rootstock. No differences were observed for yield, fruit number, fruit weight, or time to flowering of self-grafted and nongrafted scion checks. In the high tunnel, yield was higher in scions grafted onto ‘Habanero TEC’ compared with self-grafted and nongrafted checks. In the open field, yield and fruit number were highest on scions grafted onto ‘Habanero TEC’. Regardless of graft treatment, high-tunnel production in tropical environments can result in significant increases in yield and fruit number compared with open-field production. No advantage of grafted plants was observed in the high-tunnel production environment. In contrast, in the open-field environment, grafting sweet pepper scions onto pungent habanero rootstocks resulted in a significant increase in yield, fruit number, and fruit size compared with self-grafted and nongrafted checks. The increase was likely attributable to the resistance of habanero pepper cultivars to soil-borne diseases, including bacterial wilt.

Open access

Samantha R. Nobes, Karen L. Panter, and Randa Jabbour

The objective of this study was to determine best production practices for five different specialty cut flower species at an altitude of 7200 ft. Region-specific information about cut flower production is important because of unique environmental conditions. We grew five specialty cut flower species in two different growing environments: a greenhouse and a high tunnel. Flowers were grown year-round in the greenhouse and during late spring through fall in the high tunnels. We also used pinching as another production method for the potential increase in branching. The goals were to test the effects of species, growing environment, and pinching on the days from sowing to harvest, stem length, number of stems cut per plant, and marketable yield. Experiments were conducted at the University of Wyoming Laramie Research and Extension Center in Laramie, WY, to assess the potential for producing specialty cut flowers for local consumption. The species used in this study included ‘Princess Golden’ pot marigold (Calendula officinalis), ‘Lucinda Mix’ stock (Matthiola incana), ‘Double Mix’ strawflower (Helichrysum bracteatum), ‘Dara’ ornamental carrot (Daucus carota), and ‘Celway Mix’ cockscomb (Celosia argentea). Results showed significant species × environment and season interactions, indicating the importance of species and production practice selections. We successfully sold the cut flowers to the university student farm for community-supported agriculture shares and farm market sales, as well as to a local florist for use in floral arrangements. This study concluded that careful species selection for season and growing environment is essential for the successful integration of these niche cut flowers into current or future greenhouse and high-tunnel production in Wyoming.

Open access

Huihui Zhang, Ping Yu, Min Song, Dalu Li, Qianqian Sheng, Fuliang Cao, and Zunling Zhu

Ginkgo biloba, a relict plant, has been popularized and planted in most areas of China for its leaves, timber, and fruits. In the present study, the dynamic changes in leaf color, leaf pigment content during the color change period, and photosynthetic characteristics in different growth periods were studied to explore the coloring mechanism and adaptability of five late-deciduous superior Beijing G. biloba cultivars (LD1–LD5). The results showed that the leaf color change of each superior cultivar was relatively stable, and the discoloration period of LD3 and LD5 was later than that of others. From September to November, the chlorophyll a, chlorophyll b, and total chlorophyll content in all superior cultivars showed a downward trend, except in LD3, in which the pigment content was slightly higher in October than in September. Except in LD3 and LD4, the ratio of carotene content to total chlorophyll content in other cultivars slightly decreased in October. In May, the photosynthetic capacity of LD5 was stronger than that of other cultivars. The photosynthetic capacity of LD3 was strong in July and October. Our results imply that LD3 and LD5 are suitable for mixed planting with common G. biloba to increase the overall leaf color viewing period. Ginkgo biloba leaves turn yellow in autumn because of both a decrease in the chlorophyll content after leaf senescence and an increase in the Car content during leaf senescence. Although LD5 presented rapid seedling emergence, LD3 grew faster during the vigorous and late growth stages and is thus suitable for agricultural production.

Open access

Haoran Fu, Qingxu Ma, Zhengbo Ma, Yingzhao Hu, Fan Liu, Kaijun Chen, Wankun Pan, Sheng Tang, Xin Zhang, and Lianghuan Wu

Pear (Pyrus spp.) is the third-largest economic crop in China after apples (Malus pumila Mill.) and citrus (Citrus reticulata Blanco), and it is mainly cultivated by smallholders. Currently, the yield of Chinese pear ranks midlevel globally, with only 17.9 t⋅ha−1⋅year−1, which is lower than that of the United States (36.0 t⋅ha−1⋅year−1). However, the factors limiting pear production dominated by smallholders are unclear. We interviewed 75 smallholders about 18 yield-related indicators for pear-typical planting areas. The boundary line model was used to analyze the contribution of internal factors and dominant external factors affecting yield and to simulate strategies for increasing yield through the scenario analysis. The results showed that the average gap between the average and highest attainable yields for smallholders was 10.5 t⋅ha−1⋅year−1 in Luniao County. Among individual yield-limiting factors, chemical fertilizer nitrogen (N) input (13.3%) was the most significant, followed by the soil-available N content (12.0%) and leaf magnesium content (12.0%). Overall, the contribution of all soil factors (42.7%) was the largest compared with the other factor categories. However, the contribution of internal factors could not be ignored and accounted for 25.3% of the total. A scenario analysis showed that comprehensive strategies considering soil, management, and internal factors achieved the largest yield improvement (14%), as did reducing the fertilizer application rate (66%) compared with only using soil or leaf diagnosis methods. Therefore, integrated methods should be considered when developing pear orchard management measures and include soil, management, and internal factors.

Open access

Gunbharpur Singh Gill and Juang Horng Chong

Management of sweetpotato whitefly (Bemisia tabaci), one of the most economically important pests of poinsettia (Euphorbia pulcherrima), relies heavily on neonicotinoid insecticides. Growers are seeking insecticide alternatives to neonicotinoids due to market demands. Although several systemic and translaminar insecticides have been suggested as alternatives to neonicotinoids, no published study has simultaneously compared their efficacies against sweetpotato whiteflies. This study compared the efficacies of 10 systemic and translaminar alternative insecticides with those of two systemic neonicotinoids, when all products were applied as foliar spray (twice at 14 d) or substrate drench (once) against sweetpotato whiteflies on poinsettia plants. Sweetpotato whitefly nymph and adult densities were examined 2 weeks before the first application (pretreatment), and weekly after the application for 8 weeks. Results showed that insecticides varied greatly in their efficacy, particularly against adults, and that spray application provided more effective suppression of nymphs than drench application. Spray and drench applications of imidacloprid and dinotefuran were consistently the most effective against sweetpotato whitefly nymphs and adults. Among the neonicotinoid alternatives, cyantraniliprole was the most effective insecticide in reducing sweetpotato whitefly nymph densities by both spray and drench application methods, with efficacy comparable to those of imidacloprid and dinotefuran. Although less effective than cyantraniliprole, foliar sprays of afidopyropen, chloratraniliprole, cyclaniliprole, flonicamid, flupyradifurone, pyrifluquinazon, spirotetramat, and sulfoxaflor + spinetoram were also effective against nymphs and could serve as partners in an insecticide rotation program.

Open access

Lexie McClymont, Ian Goodwin, Desmond Whitfield, Mark O’Connell, and Susanna Turpin

Vegetative growth, orchard productivity, fruit quality and marketable yield were evaluated for rootstock (D6, BP1 and Quince A), tree density (741–4444 trees/ha), and training system (Open Tatura trellis, two-dimensional vertical and three-dimensional traditional) effects on young trees of the blush pear cultivar ‘ANP-0131’. ‘ANP-0131’ is a vigorous scion and vegetative growth, precocity, and yield were influenced by the selected rootstocks. Tree density and training system treatments exerted a substantial effect on canopy radiation interception while increasing tree density improved yield. Increasing tree density from 2222 (high density) to 4444 (ultra-high density) trees/ha did not improve cumulative yield. Crop load affected fruit size, such that “marketable” yield (yield of fruit weighing between 150 and 260 g) was greatest for trees on D6 rootstock and trained to Open Tatura trellis at high and ultra-high densities.

Open access

Sarah E. Dixon, Jerri L. Henry, Dean S. Volenberg, and Reid J. Smeda

The increasing adoption of dicamba-tolerant soybean (Glycine max) increases the potential exposure of wine grape (Vitis sp.) to dicamba, to which off-target injury may occur via particle drift or vapor drift. In Missouri, at one site in 2017 and at two sites in 2018, research of production vineyards focused on the effects of dicamba on hybrid ‘Vidal blanc’ grapevines. During flowering and early fruit set, bearing grapevines were exposed to low rates of dicamba delivered as a spray solution of 81 or 161 ppm or by vapor from treated soil. Grapevines were highly sensitive to dicamba, and visible symptoms extended throughout the growing season. The severity of dicamba injury (leaf cupping and feathering) was similar at two of three site-years, with greater injury related to particle drift than to vapor drift of dicamba. Early-season injury resulted in dicamba impacting the total soluble solids (TSS) content of grape berries and grape yield. At harvest during two site-years, yield reductions of up to 45% were associated with dicamba exposure at flowering. Across all site-years, no significant effects of dicamba drift were observed in the TSS content of berries during veraison in August, as measured by refractometer. However, the final TSS content of berries at harvest in September was reduced by 12% from dicamba as particle drift. At a minimum detection level of 10 ng⋅mL−1, high-performance liquid chromatography mass spectrometry identified dicamba at levels up to 33 ng⋅mL−1 in grape must over all site-years. Unexpectedly, this was up to 125 d after grapevine exposure despite low levels of visible dicamba symptomology.

Open access

Satoru Motoki, Takumi Taguchi, Ayaka Kato, Katsuhiro Inoue, and Eiji Nishihara

Asparagus is a popular vegetable rich in healthy functional components. However, the process of its production leaves ferns from aboveground parts and roots from underground parts as unusable parts, and this is an issue to be resolved. In our previous studies, large amounts of rutin were noted in the cladophylls and storage roots (brown and epidermis), and the protodioscin content was high in buds, in the soil-covered section of spears, and in rhizomes. This study was conducted to examine the distribution of growth-inhibitory activity and mineral contents in different parts of asparagus. Correlations, including representative functional components (rutin and protodioscin), were examined. The results suggest there are differences in growth-inhibitory activity of different parts of asparagus. The growth-inhibitory activity was strong in the buds, rhizome, and absorptive and storage roots, and weak in the cladophylls and lateral branches. The percent N content of the aboveground part of asparagus was high compared with that in the aboveground part of other crops. Although the percent K content was similar to the mean of the aboveground part of other crops, it was higher than that in general green manure, suggesting the residual stems and leaves of the aboveground part of asparagus are effective green manure. In the aboveground part of asparagus, the rutin content and percent N and K content were higher, whereas growth-inhibitory activity tended to be low, suggesting that when no disease developed in the aboveground part, it can be used as an organic substance.

Open access

Alfonso Guevara, María Nicolás-Almansa, José Enrique Cos, Juan Alfonso Salazar, Domingo López, José Egea, Antonio Carrillo, Manuel Rubio, Federico García, and David Ruiz

Open access

Yen-Cheng Chiang and Pei-Yi Weng

The rapid pace of modern life, as well as chronic work and academic overloading, contribute to our society’s progressively increasing stress levels. Chronic stress can affect both physical and mental well-being. Numerous studies have confirmed that viewing a nature-based video presentation can reduce stress and result in attention recovery. However, the discourse has been primarily focused upon stimulation applied over a single duration, rather than over various durations. Therefore, the present study explored the effect of various viewing durations with regard to forest-related videos on stress reduction and attention recovery. Before the videos’ presentation, the participants’ stress and distraction levels were increased through stimulation. Data on stress, attention, and relaxation were collected through the implementation of the State–Trait Anxiety Inventory and an electroencephalogram instrument. Equal numbers from the 90 participants (i.e., 30) were assigned to watch a short, medium-length, or long video (5, 10, and 20 minutes in duration, respectively). The viewing of 20-minute forest-related videos significantly promoted stress reduction and physiological relaxation. The present findings advance the understanding of the relationship between viewing nature scenes duration and psychophysiological states; thus, they serve as a reference for future research on the natural-dose concept, as well as the development of relevant activities and courses.