Stinging nettle (Urtica dioica) is a specialty crop with economic potential. Apart from being harvested and consumed as a leafy vegetable, stinging nettle has well-documented applications in alternative medicine and industry. However, research on stinging nettle mineral nutrition is insufficient and the current study is part of efforts to establish agronomic guidelines for managed cultivation. Greenhouse experiments were conducted over two seasons (summer and fall) to evaluate stinging nettle growth and dry matter partitioning in response to variations in the supply of nitrogen (N), and N in combination with potassium (K). In the first experiment, seedlings were transplanted into potted media amended with N applied at rates equivalent to 0, 15, 30, 45, 60, and 75 g·m−2, while Expt. 2 consisted of N (15, 45, and 75 g·m−2 equivalent) and K (4, 8, and 12 g·m−2 equivalent) applied in factorial combinations. In Expt. 1, stinging nettle growth was positively correlated with N supply up to 60 g·m−2 during the reproductive phase (summer) and 75 g·m−2 during the vegetative phase (fall), while there was a slight decline in growth and dry matter yield at the highest level of K (12 g·m−2) at all N levels in Expt. 2. In both experiments, growth and dry matter accumulation was higher in the fall than in summer, and high N accounted for significantly more vegetative growth with a concomitant increase in aboveground biomass. Our results suggest that K should be applied at a rate below the growth-limiting threshold of 12 g·m−2. In this study, N strongly stimulated aboveground growth suggesting it is the most important element in stinging nettle nutrition.
Laban K. Rutto, Myong-Sook Ansari and Michael Brandt
Guo-Liang Jiang, Laban K. Rutto and Shuxin Ren
Edamame is a vegetable or specialty soybean (Glycine max (L.) Merr.) with high nutrition and market value. The market demand for edamame has significantly increased in the United States since its health and nutritional benefits became recognized. However, there are a limited number of domestically developed or improved edamame cultivars in the United States, and the knowledge of edamame is very limited. In this study, 86 breeding lines and cultivars of maturity group (MG) V and VI developed in the United States were evaluated in replicated field trials for edamame yield and agronomic traits in Virginia in 2015 and 2016. The results indicated that there were significant differences among the genotypes and between years in all the traits investigated (plant height, fresh biomass, pod yield, pod ratio, fresh seed yield, seed ratio, and 100-seed weights), but the yearly differences for dried 100-seed weight and dried-to-fresh ratio of seeds were insignificant. Genotype-by-year interaction effects were not significant in most cases. Estimates of the broad sense heritability varied with traits, from 23% to 88%. Coefficients of phenotypic and genotypic correlation were mostly low, but fresh pod and seed yields were highly correlated. Fresh biomass exhibited a positive phenotypic correlation with pod and seed yields, but the genotypic correlation coefficients were not significant. Twelve breeding lines were preliminarily identified to have greater edamame yield and desired traits. The information generated in this study will be helpful for edamame breeding and commercial production.