T. Casey Barickman

Selenium Influences Glucosinolate and Isothiocyanates and Increases Sulfur Uptake in Arabidopsis thaliana and Rapid-Cycling Brassica oleracea

This study investigated the impact of Se on glucosinolates (GSs) and isothiocyanates (ITCs). Plants of Arabidopsis thaliana cv. Columbia and a rapid-cycling base population of Brassica oleracea were grown hydroponically under different Se and S concentrations. The objective was to determine the effects of increasing Se and S concentrations on the GSs and ITCs. The results indicate that S and Se concentrations increased in A. thaliana and B. oleracea leaf tissue in response to increasing Se treatments. Aliphatic and total GSs decreased significantly (P ≤ 0.001) from 0.0 to 3.2 mg Se L(-1) in B. oleracea and A. thaliana leaf tissues. Consequently, aliphatic and total ITCs decreased significantly (P ≤ 0.001) from 0.0 to 3.2 mg Se L(-1) in B. oleracea and A. thaliana leaf tissues. Data demonstrate that high levels of anticarcinogenic GSs can be maintained as the Se concentration is increased to 0.8 mg L(-1). Thus, it is feasible to increase Se to beneficial dietary levels without compromising GS concentrations.

RATIO OF CALCIUM TO MAGNESIUM INFLUENCES BIOMASS, ELEMENTAL ACCUMULATIONS, AND PIGMENT CONCENTRATIONS IN KALE

Producers use elemental ratios, such as calcium (Ca): magnesium (Mg), in fertility programs to ensure sufficient nutrient uptake. Kale (Brassica oleracea L. var. acephala D.C.) accumulates high levels of carotenoids which can be beneficial for human health. Objectives were to determine the influence of Ca:Mg fertilization on 1) biomass, 2) essential nutrients, and 3) carotenoids in kale leaf tissues. ‘Redbor’ kale was greenhouse-grown in solution culture. Ca:Mg ratio treatments were 9:1, 6:1, 3:1, 1:3, 1:6, and 1:9. Ca:Mg ratio significantly affected biomass, nutrient accumulation, and carotenoids. Plant biomass decreased linearly (P ≤ 0.001) and β-carotene, lutein, neoxanthin, and antheraxanthin all increased, then decreased quadratically (P ≤ 0.001) as the ratio of Ca:Mg changed from 9:1 to 1:9. Ca:Mg ratio also affected leaf tissue Ca, Mg, potassium (K), sulfur (S), boron (B), manganese (Mn), molybdenum (Mo) and zinc (Zn). Results indicate that producers wishing to maximize elemental uptake and carotenoid content of kale need to consider the ratio of Ca:Mg in their fertility programs.

IMPACT OF SELENIUM FERTILIZATION ON GLUCOSINOLATE CONCENTRATION IN ARABIDOPSIS THALIANA AND RAPID CYCLING BRASSICA OLERACEA

Brassica vegetables are a significant source of glucosinolates (GSs), which are sulfur (S)-containing phytonutrients exhibiting, upon hydrolysis by endogenous myrosinase, antioxidant and anti-carcinogenic activity. Selenium (Se) is an essential micronutrient in mammalian health exhibiting antioxidant activity by inhibiting experimental carcinogenesis in animal models and reducing cancer incidence in human clinical trials. Selenium is readily accumulated in both Brassica species and Arabidopsis thaliana, a model species with similar S-metabolism. The research objectives for this project were to: 1) compare the impact of Se fertilization on GS concentrations between Arabidopsis thaliana and rapid cycling Brassica oleracea; and 2) determine the level of Se fertilization needed to optimize plant tissue Se concentration to maximize potential human health benefits. Both S and Se concentrations increased in A. thaliana and B. oleracea tissues in response to increasing Se treatments. Concentrations of glucoiberin, glucoraphanin, aliphatic, and total GS differed significantly between A. thaliana and B. oleracea. Data demonstrates that anti-carcinogenic GSs can be modified through changes in Se treatment concentrations, yet high levels of anti-carcinogenic GSs can be maintained while increasing Se concentration to 0.8 mg Se L-1. Thus, it is feasible to increase Se to beneficial dietary levels without compromising GS concentrations.

Preemergence Herbicide Effects on Hybrid Bermudagrass Root Architecture and Establishment

Determine the effects of commonly used PRE herbicides on hybrid bermudagrass root architecture and establishment. Introduction Hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) is commonly produced as sod in the southern US and other warm-season climates around the world. Preemergence herbicides are sometimes used to control annual weeds. However, these herbicides may negatively affect hybrid bermudagrass establishment from sprigs and/or sod. Preemergence Herbicide Effects on Hybrid Bermudagrass Root Architecture and Establishment Erick G. Begitschke, James D. McCurdy, Te-Ming (Paul) Tseng, T. Casey Barickman, Barry R. Stewart, Christian M. Baldwin, Michael P. Richard, and Maria Tomaso-Peterson Mississippi State University

Effects of abscisic acid and calcium on tomato fruit aroma volatiles

ABSTRACT Aroma volatiles are derived from precursors, such as amino acids, fatty acids and carotenoids in tomato fruit. Volatiles enhance the main flavor components in the fruit, particularly sugars. Abscisic acid (ABA) is derived from the carotenoid pathway and there may be an indirect connection to this pathway. Therefore, the purpose of this study was to examine the influence of ABA on tomato fruit volatiles. This study identified five flavor volatile compounds that were consistently present in “Mt. Fresh Plus” tomato fruit tissue. They were 2-methyl furan, (E)-2-hexeanl, 1-hexanol, hexenal, and 6-methyl-5-hepten-2-one. ABA treatments did not have an effect on volatile concentrations in “Mt. Fresh Plus” tomato fruit. Majority of the volatiles identified did not differ between the ABA treated plants and the ABA control plants. However, ABA treatments did significantly decrease (E)-2-hexenal. These results indicated that ABA treatments did not have a major effect on the aroma volatile profile of the fruit.

Abscisic acid improves tomato fruit quality by increasing soluble sugar concentrations

ABSTRACT Abscisic acid (ABA) is crucial in fruit maturation and senescence and is considered as the other ripening control factor other than ethylene. Important components in ripening fruit are soluble sugars, which make the fruit sweeter and carotenoids, important flavor compounds in ripened fruit. The purpose of this study was to examine the effects of foliar ABA and calcium (Ca) fertilizer treatments (individually and in combination) on determinate beef-steak greenhouse tomato (Solanum lycopersicum) leaf chlorophylls and carotenoids, fruit carotenoids, and soluble sugar concentrations. Foliar spray treatment of 500 mg L−1 ABA increased zeaxanthin (ZEA) and β-carotene (BC) in tomato leaf tissue. Increases in Ca fertilizer treatments significantly decreased tomato leaf violaxanthin (VIO), but no effect on other carotenoids. The application of 500 mg L−1 ABA foliar spray significantly increased glucose and fructose concentrations in tomato fruit tissue. Foliar application of ABA treatments can increase overall chlorophyll, carotenoid content, and fruit quality.