Browse
You are looking at 101 - 110 of 41,721 items for
Crapemyrtle (Lagerstroemia sp.) is a top-selling deciduous flowering tree in the United States, and its salability is often compromised by cercospora (Cercospora lythracearum Heald & F. A. Wolf) leaf spot. To compare cercospora leaf spot resistance, 32 crapemyrtle cultivars belonging to Lagerstroemia indica, Lagerstroemia fauriei, L. indica × L. fauriei, and L. indica × L. fauriei × Lagerstroemia limii and 12 cultivars or unnamed selections belonging to L. indica, L. indica × L. fauriei, L indica × L. fauriei × L. limii, L. limii, and Lagerstroemia subcostata were planted in field plots in 2004 and 2011, respectively. The experiment was a completely randomized block design with three and four replications in the 2004 and 2011 plantings, respectively. Plants were evaluated for cercospora leaf spot disease severity and defoliation using a scale of 0% to 100% foliage affected from August to October of 2015, 2016, and 2017. Area under the disease progress curve (AUDPC) was calculated for the evaluation period of each year. L. fauriei cultivars Fantasy, Kiowa, Townhouse, and Woodlander’s Chocolate Soldier and L. indica × L. fauriei Apalachee from the 2004 planting, and the L. subcostata and L. limii selections from the 2011 planting had lowest cercospora leaf spot disease severity ratings, AUDPC, and defoliation. L. indica × L. fauriei cultivars Choctaw, Miami, Natchez, Osage, Sarah’s Favorite, Tonto, Tuscarora, and Tuskegee, and L. indica × L. fauriei × L. limii Arapaho were moderately resistant to cercospora leaf spot, whereas cultivars belonging to L. indica and L. indica × L. fauriei × L. limii Cheyenne were highly susceptible to cercospora leaf spot. Results from this research may aid breeders, nursery producers, and landscapers in selecting crapemyrtle species and cultivars with cercospora leaf spot resistance.
Plant reserves play a key role in woody perennial plant winter survival and growth resumption in the spring. In fruit crops, reserves are critical for production in temperate climates when nutrient uptake is minimal and photosynthate production is limited in newly emerged leaves. Fall nitrogen (N) fertilization can be used to increase the availability of plant reserves to support and enhance vegetative growth and fruit production the following growing season. The objective of this study was to test the effect of fall N fertilization on fruit production by evaluating yield components and their relationships to vegetative growth. A split-plot design was established in three ‘HyRed’ cranberry production beds at a farm in central Wisconsin in a 3-year study. Fall N treatments were the main effect and consisted of plots receiving a single application of 0%, 10%, 20%, and 40% of the standard N application (67 kg⋅ha–1) used during the growing season. Summer N fertilization treatments were split in five weekly applications as subplots and consisted of a complete (100%) and a balance (60%, 80%, and 90%) of the standard N application (67 kg⋅ha–1) used during the growing season. Yield was unaffected by either the fall or summer fertilization treatments, but there was an increase in berry weight and a reduction in the number of fruit per unit area using the 40% fall N fertilization treatment. The lower number of fruit per unit area resulted from an increase in the proportion of vegetative uprights—a phenomenon related to an increased length of uprights. Prolonged growth may have affected the flower bud induction window, which occurs in early fall. The fall N fertilization effect of increased vegetative growth may have been the result of an increased availability of N in spring. This result could be advantageous in the establishment of new beds or the recovery of vines that have experienced stress.
Huanglongbing {HLB [Candidatus Liberibacter asiaticus (C Las)]} has been one of the biggest challenges in citrus (Citrus sp.) production in Florida and wherever it is present. HLB-affected trees show significant shoot and root dieback, fruit drop, and reduction in yield. Currently, there is no cure for HLB, and there is no commercial HLB-resistant germplasm. Nonetheless, intensive nutrient management has been promising for citrus growers. The nutrient requirement of HLB-affected trees seems to be greater than that of healthy citrus trees. By understanding the nutrient uptake potential of rootstocks, fertilizer programs can be customized accordingly to enhance the performance of a rootstock in existing groves. Moreover, a reduction in the application of nutrients is possible by planting rootstocks with a high nutrient absorption capacity. Use of rootstocks with good nutrient uptake efficiency can take some burden off the growers who are intensively managing HLB-affected citrus groves. Therefore, the objective of this study was to evaluate and understand the nutrient uptake potential of the citrus rootstocks. To achieve this objective, a 100% hydroponic greenhouse study was conducted with six rootstocks with a range of tolerance to HLB. Several physiological and molecular tools were applied to evaluate the rootstocks for their nutrient uptake potential. A+Volk × O-19 (HLB-tolerant) rootstock had greater nutrient uptake efficiency, whereas US-896 (HLB-susceptible) had lesser nutrient uptake efficiency. Swingle, one of the most popular pre-HLB rootstocks, had poor zinc uptake and the least expression of ZINC TRANSPORTER, suggesting that zinc applications should be emphasized in Swingle plantings. US-896 rootstock expressed the least level of nutrient transporter genes, such as IRON TRANSPORTER. UFR-4 (a good performer under HLB conditions) had a large root biomass, but the uptake efficiency for nutrients was poor, suggesting that the nutrient uptake potential is a complex process that is not solely dependent on root biomass. This study is unique because it is one of the first citrus studies to report nutrient uptake efficiency and the potential of rootstocks. The information presented can be used to improve performance or select better-performing rootstocks under HLB conditions.
Rambutan (Nephelium lappaceum L.) (Sapinadeae) fruit, a nutritional staple in Hawaii, exhibits desiccation and physiological browning soon after harvest, and methods to prolong shelf life may be commercially advantageous. In this study, freshly harvested fruit were treated with pectin coatings with or without trans-cinnamaldehyde (TCIN) and stored at 10 °C or 20 °C (room temperature) to evaluate postharvest quality attributes. Control fruit were treated with deionized water only. To find the best formulation of the coatings, three concentrations of TCIN were incorporated into a pectin solution to get 0.05% TCIN, 0.1% TCIN, and 0.2% TCIN coatings. At 0, 2, 4, and 6 days postharvest, fruit stored at 20 °C were evaluated for weight loss, firmness, pericarp browning, sugar, acid, and taste. The results showed that the 0.1% TCIN coating exhibited significantly lower weight loss than both control and the 0.2% TCIN coating through the entire storage time at 20 °C. The 0.1% TCIN coating–treated fruit were significantly firmer than control after 4 days of storage at 20 °C. The 0.1% TCIN coating also significantly reduced the pericarp browning over the control. Therefore, we selected 0.1% TCIN coating for fruit storage at 10 °C for up to 15 days. At 10 °C, the control fruit showed significantly higher pericarp browning than all TCIN-containing coated fruit. The 0.1% TCIN-treated fruit showed a significantly higher overall quality value than control fruit. The results indicate that the 0.1% TCIN coating may extend the commercial shelf life of rambutans and other perishable fruits. By extending shelf life, this coating can reduce postharvest losses and facilitate expanded fruit exports in Hawaii.
Garlic (Allium sativum L.) is an important plant species because of its nutritional and medical value. One of the important advantages of plant tissue culture is in vitro selection. The tolerance of garlic to some heavy metals under in vitro conditions was studied. In vitro experiments were carried out in Murashige and Skoog (MS) nutrient medium supplemented with different doses of cadmium (Cd), cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), chromium (Cr), and lead (Pb) at 100 µm, 200 µm, 300 µm, 400 µm, and 500 µm. During experiments, plant length, number of leaves, leaf length, root number, and root length parameters were considered. In the findings, there was a decrease in both leaf and root development as doses of heavy metals increased. In addition, it has been found that the decrease in plant development at doses of 400 µm and 500 µm was higher compared with other doses. There was no root formation at high doses of Cd, Co, Ni, and Cu (400 µm and 500 µm). As a recommendation, further research should be conducted under in vivo conditions to evaluate the level of tolerance to heavy metals in garlic.
Soil salinization is an environmental problem globally. Bermudagrass (Cynodon dactylon) has long been used for soil restoration in saline-alkali land. Urbanization and the compound planting pattern combining trees, bushes, and grasses induced shading are becoming one of the most significant environmental constraints on the management of bermudagrass, which directly affects photosynthetic characteristics. Salinity and shade have become the most important environmental constraints on lawn development and implementation. Previous studies have shown that the plant physiological response under combined stress was different from that under single stress. The purpose of this research was to investigate the effects of salinity stress, shade stress, and the combined stress on bermudagrass. Shade nets were used to simulate shade stress to 85% shade. The NaCl concentration gradient for salinity stress was 1.0% for 7 days, 1.5% for 7 days, and 2.0% for 13 days, respectively. The combined stress combines the two approaches mentioned previously. The results showed that the salinity stress significantly inhibited the plant height, leaf relative water content, chlorophyll content, the chlorophyll a fluorescence induction (OJIP) curve and other photosynthetic parameters of bermudagrass while increasing electrolyte leakage when compared with control. Shade stress significantly enhanced the plant height, chlorophyll content, electrolyte leakage, the OJIP curve, and other photosynthetic parameters. Under the combined stress, the plant height and relative water content did not change significantly, but the photosynthetic parameters such as chlorophyll content and the OJIP curve increased. Furthermore, under the combined stress, the photosynthesis-related genes were regulated. Salinity stress inhibited the photosynthetic ability of bermudagrass more than shade stress, while the combined stress exhibited a considerably better photosynthetic ability. These findings provide information for the usage of bermudagrass in salinized shade conditions.
Research has confirmed that there are physical and mental benefits associated with performing horticultural activities, such as being in contact with soil and viewing plants. In addition, due to the rapidly increasing volume of affective neuroscience research, it is now possible to understand emotional processing in the brain through neuroimaging. The present study was conducted to explore subjects’ emotional responses after participating in horticultural activities, with functional magnetic resonance imaging (fMRI) and the Profile of Mood States used for physiological and psychological measurements, respectively. First, the subjects’ baseline brain activation levels were determined before any engagement in horticultural activities. A week later, the subjects participated in a 5-week horticultural activity. fMRI was used to detect physiological changes during the different stages of the activity—namely, preparation and sowing, fertilizing and weeding, and harvesting. The findings show that the functional connectivity of the brain regions was activated, including the emotional prosody network. Hence, this study provides evidence that gardening can stimulate functional connectivity, activation of positive emotions, and mindfulness in the brain. The findings provide a neuroscientific understanding of the types of horticultural activities that increase positive emotions, meditation, creativity, attention, and relaxation and reduce depression.