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Allelopathy plays crucial roles in invasive plant viability and agricultural production systems. However, there is no well‐established hands‐on learning activity to teach the concept of allelopathy. Nor is there an activity which allows students to gain knowledge about glucosinolates and their corresponding enzyme, myrosinase, which are present in almost all Brassica crops. Lettuce germination was counted by the students from three different treatments including water treated with Parafilm sealing, horseradish treated with Parafilm sealing, and horseradish treated without Parafilm sealing. Additionally, lettuce root length was measured by students using ImageJ software from each treatment using pictures captured by students' smartphones. Students took an identical quiz as a pre‐laboratory and a post‐laboratory assignment. Their average scores on the pre‐laboratory and post‐laboratory quizzes were 3.14 and 6.56 out of 10, respectively, indicating the lab activity significantly improved students' understanding of allelopathy and glucosinolate‐myrosinase system. In addition, students (n = 76) completed a survey post‐laboratory to assess their self‐efficacy. This simple and cost‐effective laboratory activity improved students' knowledge and skill development as it made learning more inviting, meaningful, and fun. © 2019 International Union of Biochemistry and Molecular Biology, 47(3):333–340, 2019.

In the present study, we assessed the allelopathic effects of various concentrations (0%, 0.1%, 0.2%, and 0.3%) of horseradish root extract (HRE) on onion root. The average growth of onion root tips during the 0% HRE treatment (deionized water treatment) was 0.9 cm/day, which was the highest among the growth rates obtained with all HRE treatments. Moreover, the average growth during 0.3% HRE treatment was 0.1 cm/day. During cell cycle analysis, the mitotic phase fraction of the control (deionized water treatment) cells was 6.5% of all dividing cells, with this percentage being the highest among the values obtained for all treatment groups. In the control group, all cell cycle phases were identified; however, in the 0.1%, 0.2%, and 0.3% treatment groups, telophase was not identified. The ROS accumulation area of the onion root decreased, as the HRE treatment concentration increased. In the control root, the area of dead tissue was 0%; however, in the 0.1% and 0.2% HRE treatment roots, the ratio was 5% and 50%, respectively. These findings indicate that the allelopathic effect of HRE depends on the concentration of HRE applied to the onion root.

Dietary minerals play an important role in human nutrition and proper metabolism. We grew various Brassica crops under field conditions in 2012 and 2013 and analyzed 8 essential minerals from edible tissues of those crops. Among the investigated crops, pak choi (Brassica rapa), mustard greens (B. juncea; B. nigra), and komatsuna (B. rapa) were generally high in most minerals, according to dry weight-based concentrations. The percentage recommended daily intake (RDA) or adequate intake (AI) values, calculated using fresh weight-based concentrations, suggest that Brassica vegetables are a good source of iron, calcium, and manganese, providing > 20% of %RDA/AI depending on crop. Kale (B. oleracea; B. napus) was generally higher in %RDA/AI, in particular for calcium (Ca), phosphorous (P), magnesium (Mg), and manganese (Mn). From the 2-year study, days to harvest, growing degree days, total solar radiation, and total precipitation and evaporation were found to affect the concentration of Ca, P, Ma, and Me. The results of this study provide a direct comparison of the mineral composition of various Brassica crops grown under the same conditions and will help consumers' food choice for better nutritional value.

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