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Open access

Fei He, Tatiana Borisova, Kevin Athearn, Robert Hochmuth, and Charles Barrett

State and federal policies in the United States focus on agricultural best management practices (BMP)—such as improving nutrient management—to address water quality issues. BMP development is a challenging process as a new BMP may also affect farm profitability. This article explores the economic feasibility of nitrogen (N) management programs, including nitrogen application rates (N rates), given alternative scenarios for current nitrogen use and producer risk perceptions of carrot production in Florida. In this study, eight alternative N rates are ranked to find the economically optimal BMP. Carrot profitability is determined based on carrot yields per hectare, input costs, and carrot sale prices, using data from a 2-year carrot production experiment. The analysis applied stochastic simulation to account for the uncertain factors by using Simetar Add-In for Excel. We found that 224 kg·ha−1 N fertilizer rate is the most preferred by the producers among the eight rates considered. According to Florida’s agricultural water policy, BMP recommendations should balance water quality improvements and agricultural productivity. We consider the potential reduction of nitrogen fertilizer rate BMP from 224 kg·ha−1 to 168 kg·ha−1 and show that the effect of such reduction depends on producers’ current fertilizer application rates and their risk aversion levels. For example, reducing the N fertilizer rate from 336 kg·ha−1 to 168 kg·ha−1 decreases mean net returns by only 2% ($49/ha). In contrast, reducing the nitrogen fertilizer rate from 224 kg·ha−1 to 168 kg·ha−1 reduces the mean net returns by $151/ha, with an almost 10% reduction in the certainty equivalent of the net returns (for extremely risk-averse producers). Overall, if most producers in the region are very or extremely risk-averse, and if most of them operate close to the optimal level of fertilizer use, then setting the more restrictive BMP of 168 kg·ha−1 N can be perceived as undermining their economic profitability and require significant cost-share incentives to ensure targeted 100% adoption of BMP recommendations.

Open access

Shilun Gao, Yuan Gao, Ying Yang, Liming Jia, and Xuehuang Weng

Nutrient deficiency leads to a high fruit abscission rate and low yields of Sapindus mukorossi Gaertn. (Soapberry), which is one of the most widely cultivated biodiesel feedstock forests in China. Exogenous sucrose can provide a solution to nutrient deficiency and fruit abscission leading to low yields; therefore, it was applied to whole trees at two stages, 20 days before blooming (DBB stage) and before fruit abscission [days before fruit abscission (DBFA) stage]. Six sucrose concentrations, 0%, 1%, 1.5%, 3%, 5%, and 7%, were sprayed three times using a completely randomized block design with five replications and six treatments. 13CO2 labeling experiments were performed after the three sprayings. The results indicated that the 3% treatment had the highest yield, reaching 15.9 kg/tree. During the DBB stage, the 3% treatment significantly increased the inflorescence fructose and glucose contents 1- to 1.2-times and resulted in the highest fruit gibberellic acid, leaf indole acetic acid (IAA), fruit IAA, and fruit zeatin contents; however, it decreased the inflorescence abscisic acid (ABA) from 16 μg/g to 4 μg/g. The 1.5% and 3% treatments significantly increased the carbohydrate content and decreased the fruit ABA content to 30% to 50% of the control level during the DBFA stage. High-concentration sugar treatment (>3%) increased the nitrogen, phosphorus, and potassium contents, which decreased the calcium and magnesium contents. The 13C-dispatching ability of the inflorescence was three-times greater than that of leaves under the high-concentration sugar treatment during the DBB stage. Supplying 1.5% sucrose nearly doubled the allocation capacity during the DBFA stage. The source-sink nutrient migration pathway showed that leaf and fruit sugars were directly correlated with phosphorus. Fruit fructose and glucose contents affected the leaf mineral element contents.

Open access

David P. Leon-Chang, David R. Bryla, Carolyn F. Scagel, and Bernadine C. Strik

Although northern highbush blueberry (Vaccinium corymbosum L.) fields are often fertigated using soluble or liquid fertilizers, recommendations for applying most nutrients to the crop, including K, are based on the use of granular fertilizers. The objective of the present study was to compare fertigation to granular application of K in a mature planting of Duke, a popular early season blueberry cultivar that ripens from June through July in Oregon and Washington. The plants were grown on raised beds and irrigated using two lines of drip tubing per row. Treatments were initiated in 2016 and included no K fertilizer, a single application of granular potassium sulfate (K2SO4) in April, and fertigation once a week from April to August with soluble K2SO4 or liquid potassium thiosulfate (K2S2O3). Each treatment was applied for 2 years at a total rate of 70 kg·ha−1 K per year. The plants were also fertigated with 168 and 224 kg·ha−1 N in 2016 and 2017, respectively, and 30 kg·ha−1 P per year. Although extractable soil K was initially low at the site (144 mg·kg−1), the treatments had no effect on plant dry weight, yield, fruit quality, or the concentration of K in recently expanded leaves. However, during the first year of the study, K fertigation with K2SO4 or K2S2O3 reduced soil pH and increased the concentrations of K+, Ca2+, Mn2+, and SO4 2− in the soil solution under the drip emitters compared with no K or granular K2SO4, whereas granular application of K2SO4 resulted in higher concentrations of K+ between the emitters than any other treatment. Fertigation also affected the concentration of K in the fruit during the first year, although in this case, the concentration was lower with K fertigation than with no K or granular applications of K2SO4. During the second year, fertigation and granular K continued to result in higher concentrations of K+ in soil solution under and between the drip emitters, respectively, but at this point, extractable soil K was higher with each of the K fertilizers than with no K. Consequently, the concentration of K in leaves sampled from entire plants in late September that year was higher with any of the K fertilizers than with no K. Potassium fertilization also altered concentrations of other nutrients in the plants, including Mg, S, B, Cu, and Mn in the leaves; Ca, Mg, and B in the fruit; Mn and Zn in the woody canes; and P, Mg, S, and Mn in the crown. In many cases, concentrations of these nutrients were higher with one or more of the K fertilizers than with no K. Thus, regardless of the application method, K2SO4 and K2S2O3 appear to be good sources for increasing availability of K and other nutrients in the plants and soil. However, the amount of K in the plants was sufficient at the site, and therefore, none of the fertilizers provided a short-term benefit to growth or fruit production in the present study.

Open access

Chuan Shen and Xia Li

Amorphophallus belongs to the family Araceae and contains a high-molecular-weight polysaccharide that was originally extracted from corms called Konjac glucomannan. During the past 10 years, a vast body of research of Amorphophallus konjac has been published. Based on the Web of Science literature database, this work used Co-Occurrence, VOSviewer, and SciMAT bibliometrics analysis software tools to conduct literature analyses and big data mining of Amorphophallus Konjac research from Jan. 2012 to Dec. 2021. Therefore, the present research sorted the development process of this field and analyzed the popular changes in research topics by combing through the visualization of the analysis results to systematically review and forecast the research of Amorphophallus Konjac-related fields. This work discusses current research trends and hotspots and explores and analyzes the content that needs improvement to provide a reference for follow-up research.

Open access

Elizabeth Mitcham, Claire Adkison, Nico Lingga, and Veronique Bikoba

Four cultivars of English walnut (Juglans regia) were evaluated by a trained taste panel after 6 and 12 months of storage. English walnuts were stored at 5, 15, or 25 °C, and at 40%, 60%, or 80% relative humidity within each temperature. Principal component analysis was used to compare taste, texture, and aroma attributes evaluated by the taste panel to objective indicators of English walnut quality including water activity, moisture content, free fatty acids, peroxide value, hexanal content, and kernel color. Temperature was found to significantly impact English walnut oxidation and perceived rancidity, whereas storage at high relative humidity affected English walnut texture and accelerated quality loss. Water activity was more strongly correlated to textural changes than moisture content. The effect of relative humidity was more pronounced at lower temperatures, leading to increased hydrolytic rancidity and free fatty acids. Peroxide value had higher and more significant correlation to sensory attributes related to rancidity than hexanal. Free fatty acids were not correlated to the rancid sensory attribute, but were significantly correlated to bitter. English walnuts stored at 5 °C with 40% or 60% relative humidity were associated with the sweet sensory attribute and L* value (light color). Kernel darkening was associated with bitter and rancid, but a causal relationship is unknown. Sensory quality of English walnuts is complex and requires further study to establish thresholds for chemical indices of English walnut quality loss based on organoleptic perception.

Open access

Abby Pace, Bruce L. Dunn, and Charles Fontanier

An experiment was conducted to quantify luminescence of white cut flower carnations after exposure to blue glow-in-the-dark powder. Powder was applied to the flowers as either dip (3, 6, or 9 g) or spray (3, 6, or 9 g) solutions in 240 mL of water for 4 seconds plus a control. Stem fresh weight, relative stem fresh weight, flower diameter, and overall solution absorption were greatest on day 4. Only the 6-g dip or spray had greater average flower quality ratings than the control, indicating reduced vase life, but there was no difference among powder treatments. Phosphorescence is possible with fluorescent light, but ultraviolet light increased the flower mean brightness an average of 75% across all treatments. No treatment differences were observed for the flower mean brightness with ultraviolet light, except on day 9; however, greater powder rates without ultraviolet light in general resulted in greater brightness.

Open access

Grant L. Thompson, Cynthia L. Haynes, and Samantha A. Lyle

High-resolution scans of plant cuttings were made for a plant identification course to create additional study resources. Stems, flowers, leaves, and other parts with identifiable features were cut and placed on a high-quality flatbed scanner. A framework suspended a black background cloth above the cuttings to create a dark scanning environment, and it was placed far enough away from the scanner glass so as not to appear in the scanned image. Botanical scans can be shared, manipulated, composed, and otherwise provided to students for study materials. Scans are complementary to other common study aids such as pressed herbarium samples or photography.

Open access

Shane R. Evans, Kelly Kopp, Paul G. Johnson, Bryan G. Hopkins, Xin Dai, and Candace Schaible

Recent advances in irrigation technologies have led many states to incentivize homeowners to purchase United States Environmental Protection Agency WaterSense-labeled, smart irrigation controllers. However, previous research of smart controllers has shown that their use may still result in excess water application when compared with controllers manually programmed to replace actual water loss. This study compared kentucky bluegrass (Poa pratensis) irrigation applications using three smart irrigation controllers, a conventional irrigation controller programmed according to Cooperative Extension recommendations, and the average irrigation rate of area homeowners in Utah during 2018 and 2019. Of all the controllers tested, the manually programmed controller applied water at amounts closest to the actual evapotranspiration rates; however, smart controllers applied from 30% to 63% less water than area homeowners, depending on the controller and year of the study. Kentucky bluegrass health and quality indicators—percent green cover and normalized difference vegetation indices—varied between years of the study and were lower than acceptable levels on several occasions in 2019 for three of the four controllers tested. Compared with the results of similar studies, these findings suggest that the effects of smart irrigation controllers on turfgrass health and quality may vary by location and over time.