Effect of Selenium on Glucosinolate and Isothiocyanate Concentrations in \u3cem\u3eArabidopsis thaliana\u3c/em\u3e and Rapid-Cycling \u3cem\u3eBrassica oleracea\u3c/em\u3e

Brassica vegetables play a unique nutritional and sensory role in human diets around the world. Their characteristic flavors come from the break down products of glucosinolate (GS) compounds, a large group of nitrogen (N) and sulfur (S) containing glucosides. Glucosinolates are hydrolyzed by myrosinase to isothiocyanates (ITCs) which are biologically active. Mounting evidence of this process is of scientific interest due to the potential for high consumption of Brassica vegetables containing several GSs and their respective hydrolysis products that are associated with cancer chemoprevention. Glucosinolates are sulfur-rich hydrophilic, nonvolatile plant secondary metabolites; and. over the past few decades, their importance has increased following discoveries of their hydrolysis products, ITCs, as potential anticarcinogens. The importance of selenium (Se) to human health has increased in recent years due its antioxidant potential and cancer suppression properties. Recent studies have demonstrated that certain Se containing compounds like Se-methyl-Se-Cysteine and Se-methionine are effective chemoprotective agents, reducing the incidence of breast, liver, prostate, and colorectal cancers in model systems. Brassicaa species are able to hyperaccumulate selenium at concentrations of up to 10-15 mg Se·g-1 dry weight in their shoots while growing on naturally-occurring soils containing only 0.2-10 mg Se·kg-1. The non-specific integration of Se into the S assimilation pathway enables the plant to metabolize selenoamino acids, selenocysteine and selenomethionine, into proteins. The process is believed to be the major contributor of Se toxicity in plants. The ability of hyperaccumulators to accrue and tolerate high concentrations of Se is thought to be associated with a distinct metabolic capacity that enables the plants to convert these selenoamino acids into non-protein amino acids

The Effect of Abscisic Acid on Tomato Calcium Partitioning and Fruit Quality

Tomato (Solanum lycopersicum) is a widely employed plant model system for studying fruit metabolism, development and ripening. Various environmental stress factors, such as drought and high relative humidity, can cause calcium (Ca) deficiency and lead to physiological diseases such as blossom-end rot (BER) in tomato fruit. Recent studies demonstrate that abscisic acid (ABA) triggers whole-plant and fruit-specific mechanisms to increase fruit Ca uptake and prevent BER development. The objective of this study was to evaluate the effects of exogenous ABA applications during plant development on tomato carotenoid pigments, soluble sugars, organic acids, aromatic volatiles, carbohydrates, and mineral nutrient content in ripe fruit, and to assess the impacts of ABA applications on BER by evaluating how exogenous ABA will affect the distribution of Ca between the leaves and fruit. There were a series of three experiments that examined two types of tomato plants, micro tomato and a commercial tomato cultivar \u27Mt. Fresh Plus\u27. ABA was exogenously applied to the foliar and/or root tissue. Leaves were harvested and analyzed for chlorophylls, carotenoids, and Ca concentrations. Fruit tissue was harvested at red ripe maturity and analyzed for yield, BER and fruit quality parameter, such as carotenoids, soluble sugars, organic acids and aroma volatiles. The results indicate that applications of ABA treatments to tomato plants decreased the partitioning of Ca into the leaves while increasing concentrations in the fruit tissue. ABA treatments, in combination with the Ca treatment of 180 mg⋅L-1 (milligram per liter), decreased the incidence of BER. Further, ABA treatments decreased BER even in the presents of low Ca in the fertilizer solution. Results indicate that ABA treatments are most effective in the early stages of plant development. This study demonstrated that ABA is a viable treatment to significantly improve tomato fruit quality. Specifically, ABA treatments increased tomato fruit carotenoids and soluble sugar, while decreasing organic acid concentrations. However, ABA treatments had a detrimental effect on aroma volatile concentrations. ABA treatment applications in conjunction with low Ca treatments did not prove to be effective in improving tomato fruit quality. This study demonstrated that foliar spray ABA applications are more effective than root ABA applications

Teaching Educators Basic Fruit Tree Grafting Methods

Hands-on education has proven to be successful in teaching basic grafting methods. MSU Extension developed and conducted eleven statewide workshops teaching Extension Agents and Master Gardeners preferred fruit tree grafting methods. The hands-on workshops provided specialists, agents, and Master Gardeners training on teaching fruit tree grafting classes for clientele. Each workshop consisted of a pre-test, a PowerPoint presentation, a post-test, and a grafting demonstration. Post-test scores showed a significant gain in knowledge over pre-test scores. This training can be replicated/adapted by other organizations to conduct educational outreach

Seed Priming Enhances Seed Germination and Morphological Traits of Lactuca sativa L. under Salt Stress

Seed germination is the stage in which plants are most sensitive to abiotic stress, including salt stress (SS). SS affects plant growth and performance through ion toxicity, decreasing seed germination percentage and increasing the germination time. Several priming treatments were used to enhance germination under SS. The objectives of this study were (1) to identify priming treatments to shorten the emergence period, (2) to evaluate priming treatments against the SS, and (3) to induce synchronized seed germination. Salt-sensitive ‘Burpee Bibb’ lettuce seeds were treated with 0.05% potassium nitrate, 3 mM gibberellic acid, and distilled water. All the primed and non-primed seeds were subjected to 100 mM sodium chloride (NaCl) or 0 mM NaCl (control). The seven-day experiment, arranged in a complete randomized block design with four replications, was conducted in a growth chamber maintained with 16/8 h photoperiod (light/dark), 60% relative humidity, and a day/night temperature of 22/18 °C. The result indicated that hydro-primed (HP) seeds were better synchronized under SS. Similarly, fresh mass (FM) and dry mass (DM) of cotyledon, hypocotyl, and radicle were the highest in HP lettuce regardless of SS. Electrolyte leakage was the lowest in the HP lettuce, while other priming methods under SS increased membrane permeability, leading to osmotic stress and tissue damage. Overall, hydro-priming can be a good priming method for synchronizing germination and increasing FM and DM by creating the least osmotic stress and ion toxicity in lettuce under SS

Waterlogging Causes Early Modification in the Physiological Performance, Carotenoids, Chlorophylls, Proline, and Soluble Sugars of Cucumber Plants

Waterlogging occurs because of poor soil drainage and/or excessive rainfall and is a serious abiotic stress affecting plant growth because of declining oxygen supplied to submerged tissues. Although cucumber (Cucumis sativus L.) is sensitive to waterlogging, its ability to generate adventitious roots facilitates gas diffusion and increases plant survival when oxygen concentrations are low. To understand the physiological responses to waterlogging, a 10-day waterlogging experiment was conducted. The objective of this study was to measure the photosynthetic and key metabolites of cucumber plants under waterlogging conditions for 10 days. Plants were also harvested at the end of 10 days and analyzed for plant height (ht), leaf number and area, fresh mass (FM), dry mass (DM), chlorophyll (Chl), carotenoid (CAR), proline, and soluble sugars. Results indicated that cucumber plants subjected to the 10-day waterlogging stress conditions were stunted, had fewer leaves, and decreased leaf area, FM, and DM. There were differences in physiological performance, Chl, CAR, proline, and soluble sugars. Overall, waterlogging stress decreased net photosynthesis (A), having a negative effect on biomass accumulation. However, these decreases were also dependent on other factors, such as plant size, morphology, and water use efficiency (WUE) that played a role in the overall metabolism of the plant

The Effect of Environment and Nutrients on Hydroponic Lettuce Yield, Quality, and Phytonutrients

A study was conducted with green and red-leaf lettuce cultivars grown in a deep-water culture production system. Plants were seeded in rockwool and germinated under greenhouse conditions at 25/20 °C (day/night) for 21 days before transplanting. The experimental design was a randomized complete block with a 2 × 3 factorial arrangement of cultivar and nutrient treatments that consisted of six replications. Treatments consisted of two lettuce genotypes, (1) green (Winter Density) and (2) red (Rhazes), and three nutrient treatments containing electroconductivity (EC) levels of (1) 1.0; (2) 2.0; and (3) 4.0 mS·cm−1. After 50 days, plants were harvested, processed, and analyzed to determine marketable yield, biomass, plant height, stem diameter, phenolics, and elemental nutrient concentrations. An interaction between growing season and lettuce cultivar was the predominant factor influencing yield, biomass, and quality. Nutrient solution EC treatment significantly affected biomass and water content. EC treatments significantly impacted concentrations of 3-O-glucoside and uptake of phosphorous, potassium, iron, boron, zinc, and molybdenum. Effects of growing season and cultivar on leafy lettuce yield and quality were more pronounced than the effect of nutrient solution EC treatment. Thus, greenhouse production of green and red-leaf lettuce cultivars in the south-eastern United States should be conducted in the spring and fall growing seasons with elevated nutrient solution EC of ≈4.0 mS·cm−1 to maximize yield and quality

Effects of Elevated Temperature and Potassium on Biomass and Quality of Dark Red ‘Lollo Rosso’ Lettuce

Lettuce is an economically important crop for small and medium-sized growers. When grown in adverse environmental conditions, lettuce is vulnerable to a deterioration of yield and quality. Research concerning the impact of elevated potassium (K) levels on leafy vegetables, such as lettuce, is lacking. Therefore, seeds of dark-red ‘Lollo’ lettuce were germinated under greenhouse conditions at 25/20 °C (day/night). Plants were transferred into 11-L containers and placed into growth chambers at 25 and 33 °C. Plants were grown with K treatments of 117.3 (control), 234.6 (2×), 469.2 (4×), and 4) 938.4 (8×) mg·L−1. Increasing K treatments resulted in a negative quadratic response on lettuce dry mass and generated 14% more leaf calcium at 234.6 mg·L−1. An increase in temperature from 25 to 33 °C increased leaf dry matter and biomass by 40% and 43%, respectively. Leaf water content increased by 3% as temperature increased. Plants grown at 33 °C had greater quercetin glycosides compared to plants grown at 25 °C. The results from this study suggest that temperature is a stronger regulatory factor than increasing K in the determination of lettuce yield and quality. Increasing K concentration to 234.6 mg·L−1 results in greater concentrations of leaf minerals without compromising plant yield

Nitrogen Fertigation Rate and Foliar Urea Spray Affect Plant Growth, Nitrogen, and Carbohydrate Compositions of Encore Azalea ‘Chiffon’ Grown in Alternative Containers

The objective of this study was to investigate the plant vegetative growth, flower production, nitrogen (N) concentration, and carbohydrate compositions of Encore® azalea ‘Chiffon’ when fertigated with five N rates—0, 5, 10, 15, and 20 mM N—and grown in two types of containers, a black plastic and a biodegradable container, during one growing season. Foliar urea of 3% was applied to half of the plants in late fall to investigate its effect on plant N and carbohydrate concentrations. The paper biocontainers resulted in superior plant growth, increased plant size, dry weights, root length and surface area compared with the plastic containers with N rates of 10, 15, and 20 mM. The paper biocontainers also increased N uptake and carbohydrate concentrations mainly by increasing plant biomass. High N rates of 10 to 20 mM combined with urea spray and biocontainers generally resulted in the highest plant N concentrations. Foliar urea application in late fall tended to increase plant N concentration but decreased carbohydrates, including starch, glucose, fructose, and sucrose, to varying degrees, likely due to increased N assimilation. Fall foliar urea spray can be effective in improving the N status of azalea plants without affecting plant biomass

Influence of Nitrogen and Sulfur on Biomass Production and Carotenoid and Glucosinolate Concentrations in Watercress (\u3cem\u3eNasturtium officinale\u3c/em\u3e R. Br.)

Watercress (Nasturtium officinale R. Br.) is a perennial herb rich in the secondary metabolites of glucosinolates and carotenoids. 2-Phenethyl isothiocyanate, the predominate isothiocyanate hydrolysis product in watercress, can reduce carcinogen activation through inhibition of phase I enzymes and induction of phase II enzymes. Sulfur (S) and nitrogen (N) have been shown to influence concentrations of both glucosinolates and carotenoids in a variety of vegetable crops. Our research objectives were to determine how several levels of N and S fertility interact to affect watercress plant tissue biomass production, tissue C/N ratios, concentrations of plant pigments, and glucosinolate concentrations. Watercress was grown using nutrient solution culture under a three by three factorial arrangement, with three S (8, 16, and 32 mg/L) and three N (6, 56, and 106 mg/L) fertility concentrations. Watercress shoot tissue biomass, tissue %N, and tissue C/N ratios were influenced by N but were unaffected by changes in S concentrations or by the interaction of N × S. Tissue pigment concentrations of β-carotene, lutein, 5,6-epoxylutein, neoxanthin, zeaxanthin, and the chlorophyll pigments responded to changes in N treatment concentrations but were unaffected by S concentrations or through N × S interactions. Watercress tissue concentrations of aromatic, indole, and total glucosinolate concentrations responded to changes in N treatments; whereas aliphatic, aromatic, and total glucosinolates responded to changes in S treatment concentrations. Individual glucosinolates of glucobrassicin, 4-methoxyglucobrassicin, and gluconasturriin responded to N fertility treatments, while gluconapin, glucobrassicin, and gluconasturiin responded to changes in S fertility concentrations. Increases in carotenoid and glucosinolate concentrations through fertility management would be expected to influence the nutritional value of watercress in human diets

Morphological and Physiological Response of Different Lettuce Genotypes to Salt Stress

Salt stress (SS) refers to excessive soluble salt concentrations in the plant root zone. SS also causes cellular water deficits, ion toxicity, and oxidative stress in plants, all of which can cause growth inhibition, molecular damage, and even plant mortality. Lettuce (Lactuca sativa L.) has a threshold electrical conductivity of 1.3–2.0 dS/m. Thus, this research focused on physiological, morphological, and biochemical attributes in multiple lettuce genotypes under SS compared to plants grown under control conditions. The experiment was arranged in a randomized complete block design with four replications. One month after planting, the salt treatment was applied at the rate of 100 millimoles (mM). The 0 mM salt in water treatment was considered the control. A significant effect of SS on different morphological and physiological traits was observed in one-month-old lettuce plants. PI 212099, Buttercrunch-1, and PI 171676 were highly salt-tolerant. Genotypes with high salt tolerance usually had poor growth potential under control conditions. This suggests that the morphological and physiological response of 38 lettuce cultivars towards SS is genotype dependent. Identifying SS’s physiological, morphological, and biochemical attributes in lettuce may help plant-breeders develop salt-tolerant lettuce genotypes