Kimberly A. Williams

Expression of an Arabidopsis Ca2+/H+ antiporter CAX1 variant in petunia enhances cadmium tolerance and accumulation.

Phytoremediation is a cost-effective and minimally invasive technology to cleanse soils contaminated with heavy metals. However, few plant species are suitable for phytoremediation of metals such as cadmium (Cd). Genetic engineering offers a powerful tool to generate plants that can hyperaccumulate Cd. An Arabidopsis CAX1 mutant (CAXcd), which confers enhanced Cd transport in yeast, was ectopically expressed in petunia to evaluate whether the CAXcd expression would enhance Cd tolerance and accumulation in planta. The CAXcd-expressing petunia plants showed significantly greater Cd tolerance and accumulation than the controls. After being treated with either 50 or 100μM CdCl(2) for 6 weeks, the CAXcd-expressing plants showed more vigorous growth compared with controls, and the transgenic plants accumulated significantly more Cd (up to 2.5-fold) than controls. Moreover, the accumulation of Cd did not affect the development and morphology of the CAXcd-expressing petunia plants until the flowering and ultimately the maturing of seeds. Therefore, petunia has the potential to serve as a model species for developing herbaceous, ornamental plants for phytoremediation.

Slow release versus water soluble Fertilization affects nutrient leaching and growth of potted chrysanthemum

Abstract In two experiments, ‘Charm’ and ‘Delano’ chrysanthemum [Dendranthema x grandiflorum (Ramat.) Kitamura] were grown in a peat‐based root medium using standard greenhouse cultural practices. Fertilization treatments included (1) alternate liquid fertilization (ALF): water‐soluble formulation of 15N‐4.3P‐24.9K (15–10–30) at 536 mgL‐1 N alternated with tap water irrigation; (2) Constant Liquid Fertilization (CLF): 15N‐4.3P‐24.9K(15–10–30)at268 mgL‐1 Napplied at each irrigation; (3) slow release resin‐coated fertilizer (SRR): slow release formulation of 12N‐4.3P‐14.1K(12–10–17); and (4) slow release tablets (SRT): slow release formulation of 14N‐1.7P‐4.9K (14–4–6). Irrigation volume and timing of application were arbitrary for all plants in the first experiment, but they were determined gravimetrically for each treatment in the second experiment. Irrigation volumes exceeded container capacity by 20 to 30% (leaching fractions of 0.2 to 0.3). Leachate had lower electrical conductivity and higher pH with ...

Interactions of Light Intensity, Insecticide Concentration, and Time on the Efficacy of Systemic Insecticides in Suppressing Populations of the Sweetpotato Whitefly (Hemiptera: Aleyrodidae) and the Citrus Mealybug (Hemiptera: Pseudococcidae)

ABSTRACT The impact of light intensity on the uptake and persistence of the systemic neonicotinoid insecticides, imidacloprid and dinotefuran, were evaluated in poinsettia (Euphorbia pulcherrima Willd.) and yellow sage (Lantana camara L.). Insecticide residues were measured in leaves sampled from the treated plants at four time intervals after treatment to determine the relationship between insecticide concentration and efficacy against two insect pests: sweetpotato whitefly, Bemisia tabaci Gennadius, and the citrus mealybug, Planococcus citri Risso. The insecticides were evaluated at their respective label rate and at the comparable label rate of the other insecticide under two different light environments: ambient and shade. The uptake of dinotefuran into yellow sage was more rapid at both treatment rates than both rates of imidacloprid, resulting in higher percent mortality of whitefly nymphs (89.8–100) compared with imidacloprid (14.1–89.2) across all 4 wk. Additionally, plants that received both rates of dinotefuran had fewer whitefly pupae (<1.0) at week 4 compared with imidacloprid-treated plants (23.7–25.3). The uptake of dinotefuran into poinsettia plants was also more rapid and resulted in quicker and higher percent mortality of whitefly nymphs (89.5–99.6) compared with imidacloprid (14.1–89.2) across all 4 wk. However, despite efficient uptake, the efficacy of both systemic insecticides was less for citrus mealybug where percent mortality values were <50% among all the treatments across the 4 wk. The use of the two systemic insecticides evaluated in regards to pest management in horticultural cropping systems is discussed.

Use of Precharged Zeolite to Provide Aluminum During Blue Hydrangea Production

Abstract Aluminum (Al) drenches are repeatedly applied during blue hydrangea (Hydrangea macrophylla Thunb.) production because Al is required for blue sepal coloration, but soilless root media do not retain Al. The ability of clinoptilolitic zeolite to retain and release Al, and its evaluation as the sole source of Al during blue hydrangea production, was evaluated in laboratory and greenhouse experiments. Adsorption and desorption isotherms indicated that Al is adsorbed and released by this zeolite. Clinoptilolite was precharged with Al and combined at 10–40% with a peat and perlite mix to evaluate its use as a sole source of Al during the production of mini‐pot blue hydrangea “Kuhnert.” Root medium Al, pH, and electrical conductivity (EC) were measured during production. Sepal color and growth measurements, and foliar and sepal analyses were conducted at the end of the production cycle. Aluminum from zeolite was released rapidly during the vegetative stage of production. Dry mass of plants grown with 10 and 20% zeolite was similar to the commercial control. Blue sepals were produced in the 10–40% zeolite treatments, however, growth was significantly reduced from the 30 and 40% zeolite treatments. Aluminum‐charged zeolite up to 20% of the root medium may be used as a sole source of Al during forcing and may simplify blue hydrangea production; however, its use affects phosphorus (P), potassium (K), pH, and EC management.

Nitrogen nutrition, but not potassium, affects powdery mildew development in Hiemalis begonia

Abstract For obligate parasites like Erysiphe cichoracearum, manipulation of nitrogen (N) and potassium (K) nutrition may provide an alternative control method for powdery mildew in greenhouse crops. Subsequently, Hiemalis begonias “Hilda” and “Renaissance” were grown in separate experiments with a factorial combination of three N (30, 120, 240 mg L−1) and three K (30, 120, 240 mg L−1) rates applied at each irrigation. One‐half the plants in each treatment were inoculated with E. cichoracearum, while the remaining plants were sprayed regularly with the fungicide triadimefon to prevent disease development. Plant growth and powdery mildew incidence in both cultivars were significantly influenced by N fertilization and pathogen inoculation, but relatively unaffected by K fertility. Shoot dry mass in both cultivars increased with increasing N rate up to 120 mg N/L, but decreased from pathogen inoculation. This latter response increased in magnitude with increasing N rate in “Hilda”, but not in “Renaissance”. Pathogen inoculation increased powdery mildew disease severity (PMDS) in both cultivars. Nitrogen fertilization had a positive effect on PMDS, primarily at the later production stages. Total disease epidemic for the entire production time‐course, however, was not affected by N fertilization. Plant N content was positively correlated with PMDS and AUDPC (area under the disease progress curve), although most correlations were generally low. The results suggest that N fertilization at 120 mg N/L could help limit powdery mildew incidence without compromising begonia growth and quality. The data also show that at the traditional rates used today, little if any disease control benefit would be realized from K fertilization.

Light Quality Effects on Intumescence (Oedema) on Plant Leaves

Intumescence is a physiological disorder that is characterized by abnormal outgrowths of epidermal and/or palisade parenchyma cells on the leaf, petiole or stem surfaces of affected plants. Intumescences are a different disorder than oedema based on anatomy of affected cells and causal agents. This disorder is most often observed on crops produced in controlled environments and has been reported on a wide range of plant species, including ornamental sweet potato (Ipomoea batatas), cuphea (Cuphea spp.) and solanaceous crops of tomato (Solanum lycopersicum) and potato (Solanum tuberosum). When susceptible crops are grown under ultraviolet-deficient environments, such as light-emitting diode (LED) sole-source lighting that supplies only red wavelengths, intumescences are most severe. However, the incidence of the disorder can be diminished or prevented if crops are grown in environments providing ample blue or ultraviolet wavelengths of light. End-of-day far-red lighting has also shown some promise in mitigating the disorder.

Relationship between High School Student Participation in State-level Future Farmers of America Career Development Events and Matriculation at the Host University: A Case Study in Horticulture at Kansas State University

In recent years, many horticulture departments around the United States have been concerned with recruiting and retaining an adequate number of students. One potential recruitment opportunity is the horticulture Future Farmers of America (FFA) Career Development Events (CDEs). For the time period of 1999 to 2012 (14 years), 1462 students participated in the annual state-level horticulture contests, comprising floriculture and nursery/landscape CDEs, held at Kansas State University (KSU). Using the rosters from these two CDEs, we referenced the university’s student information database to determine whether the high school students who participated as FFA horticulture CDE contestants ultimately matriculated to KSU. Fifty-two percent of former FFA horticulture CDE participants were accepted to KSU and 32% matriculated. Of these, 58% enrolled in the College of Agriculture and 19% majored in horticulture. Therefore, 3.5% of total horticulture CDE participants majored in horticulture at KSU. Students who participated in more than one horticulture CDE over time were more likely to major in horticulture at KSU compared with students who competed only once. Thirty-nine percent of students who participated in both horticulture CDEs pursued a baccalaureate program in horticulture. These two student characteristics could be used as indicator data points to target recruitment of future horticulture students. Data about the high school programs that generated contest participants were also summarized. Exceling in the CDE contests was not an indicator CDE participants would pursue a baccalaureate degree in horticulture. These analyses suggest FFA CDEs have some potential to optimize student recruitment efforts.

Evapotranspiration from Spider and Jade Plants Can Improve Relative Humidity in an Interior Environment

Citation: Kerschen, E., Garten, C., Williams, K., & Derby, M. (2016). Evapotranspiration from Spider and Jade Plants Can Improve Relative Humidity in an Interior Environment. HortTechnology, 26(6), 803-810. doi: 10.21273/HORTTECH03473-16