Phytoremediation is a potentially suitable technology for taking up large amounts of N and P during plant growth and the removal of plant material, thereby avoiding eutrophication. We compared the capacity of nine different aquatic plant species for removing total P (TP), total N (TN), and NH₄⁺-N from raw domestic sewage wastewater collected from a living area located in Guangzhou city, China, and different concentrations of artificial wastewater. The experiments were performed in two stages, namely screening and modification. In the screening stage, four plant species were identified from the nine grown in raw domestic sewage water for 36 days. In the modification stage, the TN and TP removal ability of different plant combinations were determined in artificial wastewater at different N/P concentrations. After having been grown in monocultures for 46 days, Ipomoea aquatica (90.6% and 8.8%) and Salvinia natans (67.3% and 14.2%) obtained the highest TP removal efficiency in lightly and highly polluted wastewater, respectively. The combination of S. natans and Eleocharis plantagineiformis effectively removed TP and TN from lightly polluted water, suggesting that this combination is suitable for phytoremediation of eutrophic wastewater.

There are different opinions about the relationship of two disjunctively distributed varieties Adiantum reniforme L. var. sinense Y.X.Lin and Adiantum reniforme L. Adiantum reniforme var. sinense is an endangered fern only distributed in a narrowed region of Chongqing city in China, while Adiantum reniforme var. reniforme just distributed in Canary Islands and Madeira off the north-western African coast. To verify the relationship of these two taxa, relative phylogenetic analyses, karyotype analyses, microscopic spore observations and morphological studies were performed in this study. Besides, divergence time between A. reniforme var. sinense and A. reniforme var. reniforme was estimated using GTR model according to a phylogeny tree constructed with the three cpDNA markers atpA, atpB, and rbcL. Phylogenetic results and divergence time analyses--all individuals of A. reniforme var. sinense from 4 different populations (representing all biogeographic distributions) were clustered into one clade and all individuals of A. reniforme var. reniforme from 7 different populations (all biogeographic distributions are included) were clustered into another clade. The divergence between A. reniforme var. reniforme and A. reniforme var. sinense was estimated to be 4.94 (2.26-8.66) Myr. Based on karyotype analyses, A. reniforme var. reniforme was deduced to be hexaploidy with 2n = 180, X = 30, while A. reniforme var. sinense was known as tetraploidy. Microscopic spore observations suggested that surface ornamentation of A. reniforme var. reniforme is psilate, but that of A. reniforme var. sinense is rugate. Leaf blades of A. reniforme var. sinense are membranous and reniform and with several obvious concentric rings, and leaves of A. reniforme var. reniforme are pachyphyllous and coriaceous and are much rounder and similar to palm. Adiantum reniforme var. sinense is an independent species rather than the variety of Adiantum reniforme var. reniforme. As a result, we approve Adiantum nelumboides X. C. Zhang, nom. & stat. nov. as a legal name instead of the former Adiantum reniforme var. sinense. China was determined to be the most probable evolution centre based on the results of phylogenetic analyses, divergence estimation, relative palaeogeography and palaeoclimate materials.

Although eutrophication and biological invasion have caused serious harm to aquatic ecosystems, exotic and even invasive plants have been used extensively in phytoremediation water systems in China. To identify native aquatic plants with excellent water restoration potential, two representative native floating aquatic plants from Guangdong Province, namely Ludwigia adscendens (PL) and Trapa natans (PT), were selected, with Eichhornia crassipes as a control, to study their growth status, adaptability, and nutrient removal potentials in swine manure wastewater. The results demonstrated that the two native plants offered greater advantages than E. crassipes in water restoration. Within 60 days, PL and PT exhibited excellent growth statuses, and their net biomass growth rates were 539.8% and 385.9%, respectively, but the E. crassipes decayed and died with an increasing HRT (hydraulic retention time). The PL and PT could adjust the pH of the wastewater, improve the dissolved oxygen and oxidation-reduction potential, and reduce the electrical conductivity value. The removal rates of NH₄⁺–N, NO₃⁻–N, NO₂⁻–N, total nitrogen, total phosphorus, chemical oxygen demand (COD), and Chl-a in the PL group reached 98.67%, 64.83%, 26.35%, 79.30%, 95.90%, 69.62%, and 92.23%, respectively; those in the PT group reached 99.47%, 95.83%, 85.17%, 83.73%, 88.72%, 75.06%, and 91.55%, respectively. The absorption contribution rates of total nitrogen (TN) and total phosphorus (TP) in the PL group were 40.6% and 43.5%, respectively, while those in the PT group were 36.9% and 34.5%, respectively. The results indicated that L. adscendens and T. natans are both promising aquatic plants for application to the restoration of swine manure wastewater in subtropical areas.

Manglietia crassipes, a critically endangered species narrowly distributed on Mount Dayao in Guangxi, China, is also a species of ornamental interest whose variability has not been explored. Key factors leading to its endangerment have also not been studied. Here, two experiments were conducted to test the effects of different plant growth regulators and different storage conditions on germination characteristics of M. crassipes seeds. Fruit morphology was measured, and germination characteristics of fresh mature seeds were tested in order to assess natural seed vigor. Seeds were soaked in distilled water (control), or gibberellic acid (GA₃), 6-benzylaminopurine (6-BA) or indoleacetic acid (IAA) solutions of different concentrations, for 48 h to determine their effects on seed germination. In addition, the effects of different seed storage conditions (constant 4 °C, −7 °C, −20 °C, or 25 °C for 100 days, wet stratification at 4 °C for 100 days) on seed germination were investigated. Results showed that the abortive rate of the mature fruits was high (28.9%) and fresh natural seeds had a low germination rate (G) and germination index (GI). Seed germination was inhibited with 6-BA at all concentrations, but only at less than 100 m·L⁻¹ IAA; otherwise, IAA slightly promoted seed germination. GA₃ broke seed dormancy and significantly accelerated seed germination by improving G, GI and initial germination time (IGT), especially over 2500 mg·L⁻¹. The viability of seeds declined no matter how they were stored. However, 4 °C wet stratification storage was preferable for seed vigor and germination power. Our results suggest that the high abortive rate of fruits, low germination of the natural seed, seed dormancy and its intolerance to storage, contributed to the endangerment of M. crassipes. GA₃ can break M. crassipes seed dormancy, which can be a benefit for future ornamental breeding and further protection or conservation.

Whole-genome duplications (WGDs) are widespread in plants and frequently coincide with global climatic change events, such as the Cretaceous–Tertiary (KT) extinction event approximately 65 million years ago (mya). Ferns have larger genomes and higher chromosome numbers than seed plants, which likely resulted from multiple rounds of polyploidy. Here, we use diploid and triploid material from a model fern species, Ceratopteris thalictroides, for the detection of WGDs. High-quality RNA-seq data was used to infer the number of synonymous substitutions per synonymous site (Ks) between paralogs; Ks age distribution and absolute dating approach were used to determine the age of WGD events. Evidence of an ancient WGD event with a Ks peak value of approximately 1.2 was obtained for both samples; however, the Ks frequency distributions varied significantly. Importantly, we dated the WGD event at 51–53 mya, which coincides with the Paleocene-Eocene Thermal Maximum (PETM), when the Earth became warmer and wetter than any other period during the Cenozoic. Duplicate genes were preferentially retained for specific functions, such as environment response, further support that the duplicates may have promoted quick adaption to environmental changes and potentially resulted in evolutionary success, especially for pantropical species, such as C. thalictroides, which exhibits higher temperature tolerance.