To obtain the typical growth pattern of the medicinal plant Pinellia ternata Breit., we investigated the growth of plants grown under constantly controlled environments (air temperature: 25℃, air humidity: 70%RH, day length: 12 h, light intensity: 220 μmol photon m-2 s-1 [PPFD]). The growth pattern was comparable with other plant growth patterns grown under different environmental conditions. Leaf number, leaf area, and corm weight of the plants increased over time, while dry matter content in the corm maintained at approximately 35% during cultivation. Cormlets born on the corm increased linearly during cultivation, and the weight increased significantly after 11 weeks of cultivation. The content of araban, the effective ingredient of the corm, increased linearly until 11 weeks of cultivation, after which, the content appeared to level off. Thus, we obtained the typical growth pattern of the P. ternata, which is useful for evaluating the environmental effects on the plant productivity.
Previous studies have reported that ultrafine bubbles (UFBs) can promote plant growth. However, the optimum application of UFBs has not been sufficiently clarified yet. In this study, we investigated the optimum UFB content index for lettuce cultivation. Content index (CI) was defined as the product of the pass numbers (Pn) and dilution ratio (D) and taken to be indicative of UFB density; where Pn was the number of times water was passed through the UFB generator. UFB treatment comprised three different Pn: 10 passes (P1), 25 passes (P2), and 100 passes (P3). Six UFB treatments were conducted for each Pn in six D treatments as: control, UFB 10%, UFB 30%, UFB 50%, UFB 75%, and UFB 100%. The results confirmed that there was an appropriate level of CI to accelerate the growth of lettuce in a hydroponic solution, that is, a UFB CI of 7.5―30 and 18.75―30 in the nursery and cultivation stages, respectively. However, lettuce growth was significantly smaller on CI of 100. In addition, DPPH and NBT tests were conducted to measure the total antioxidant capacity (TAC) and superoxide radical on lettuce. TAC and superoxide radical accumulation were influenced by the UFB content index.
In this study, we evaluated the impact of cadmium (Cd) supplementation on the growth of the edible cactus Nopalea cochenillifera (L.) Salm-Dyck and investigated its Cd accumulation capability by exposing hydroponically grown cladodes to 0, 1, or 15 ppm Cd for 10 weeks. The fresh weights of the daughter and mother cladodes in the 15 ppm Cd treatment were about 59.8% and 82.3% of those of 0 ppm Cd treatment (control). Cd concentration of daughter cladodes in 1 and 15 ppm Cd treatment were approximately 19 times and 65 times as high as control, and Cd concentration in all plant tissues surpassed the threshold levels of other known Cd hyperaccumulator plants. We also found that the Cd concentration was significantly higher outside than inside the vascular tissue under both the 1 and 15 ppm treatments by about 28 times and 45 times each, indicating that Cd transported from the roots accumulated outside the vascular system. These results suggest that N. cochenillifera has a high Cd tolerance and can store Cd inside plant tissues. In addition to its current role as healthy food and fodder, we believe that this cactus can be a promising candidate for Cd phytoremediation in arid regions.