Container production of Serianthes nelsonii Merr. plants for out-planting within the endemic range is a major component of the plan to recover the critically endangered tree species. We exploited the ability to prune roots with copper or with strategically placed air holes in container walls to determine if root quantity or quality would increase in comparison to traditional container design. Following 23 days of growth after transplanting, new root length and root dry weight did not differ among the container types. However, most roots from the control and copper-treated containers developed from the bottom of the root system, and direction of root growth was primarily geotropic. In contrast, the air-pruning containers produced plants with plagiotropic root growth near the soil surface. Root growth was positioned with 58% in the top two-thirds of a rhizotron window for the air-pruning, 29% for the copper-pruning, and 16% for the control containers. Our results indicate that direction but not length or dry weight of post-transplant root growth was changed by use of air-pruning containers. For a critically endangered tree like Serianthes nelsonii, the improved root morphology afforded by containers that use air-pruning of roots in the nursery may improve tree stability following transplanting.
Phytotoxicity of Se(IV), Se(VI), Cu and Zn to Sinapis alba L. seedlings was expressed by inhibition of selected physiological processes (root and shoot growth, fresh and dry biomass production, water content) and correlated with their bioaccumulation. Roots growth was inhibited more than that of shoots and only Se(IV) reduced also shoots growth (IC50= 25.8 mg L-1). Se(VI) decreased more roots (IC50= 23.6 mg L-1) than shoots growth (IC50= 461.4 mg L-1). Phytotoxicity to roots growth increased as follows: Zn < Se(VI)≅Cu < Se(IV). All metals, except Cu, decreased more roots and shoots fresh mass than that of dry mass. Water content was for all (semi)metals more depressed in shoots, however, for Zn any significant changes in roots WC were confirmed. In any case transportation index Ti overreached value 1 and that indicate metals storage in the roots; however, for control the opposite results were obtained. While the highest bioaccumulation factor (BAF) was determined for Cu in both roots (1.016) and shoots (0.271) the lowest values for this parameter were confirmed for Se(VI) in the roots (0.061) and for Se(IV) in the shoots (0.010). While in the control Cu, Se and Zn content was higher in the shoots, treatment with these metals increased their accumulation mainly in the roots. Statistically negative correlation was confirmed among Se(IV), Se(VI) and Cu accumulation in the roots and water content in the roots, and among Se(IV) and Cu accumulation in the roots and water content in the shoots.
A simple method for evaluating wheat (Triticum aestivum L.) root system characteristics at an early growth stage is needed. We used a hydrogel polymer medium to visualize the growth characteristics of seminal roots. The method is straightforward, and the medium is inexpensive and can easily be adjusted to better visualize the rooting characteristics. We found that: a) the optimum preparation conditions involve the addition of distilled water at about 98°C to the hydrogel, which leads to low root penetration resistance and enough oxygen to avoid hypoxic damage; b) 97.8% of seeds germinated and the roots of all plants that germinated penetrated the hydrogel medium. c) the hydrogel medium is well suited for observing the first opposite seminal (adventitious) roots in wheat plants, making it possible to discriminate differences in growth angles among cultivars. This strategy can be used to identify deep-rooting cultivars. This method could be used for evaluation of genetic resources.