Many semi-arid ecosystems are simultaneously limited by soil water and nitrogen (N). We conducted a greenhouse experiment to address how N availability impacts drought-resistant traits of Catalpa bungei C. A. Mey at the physiological and molecular level. A factorial design was used, consisting of sufficient-N and deficient-N combined with moderate drought and well-watered conditions. Seedling biomass and major root parameters were significantly suppressed by drought under the deficient-N condition, whereas N application mitigated the inhibiting effects of drought on root growth, particularly that of fine roots with a diameter <0.2 mm. Intrinsic water-use efficiency was promoted by N addition under both water conditions, whereas stable carbon isotope compositions (δ13C) was promoted by N addition only under the well-watered condition. Nitrogen application positively impacted drought adaptive responses including osmotic adjustment and homeostasis of reactive oxygen species, the content of free proline, soluble sugar and superoxide dismutase activity: all were increased upon drought under sufficient-N conditions but not under deficient-N conditions. The extent of abscisic acid (ABA) inducement upon drought was elevated by N application. Furthermore, an N-dependent crosstalk between ABA, jasmonic acid and indole acetic acid at the biosynthesis level contributed to better drought acclimation. Moreover, the transcriptional level of most genes responsible for the ABA signal transduction pathway, and genes encoding the antioxidant enzymes and plasma membrane intrinsic proteins, are elevated upon drought only under sufficient-N addition. These observations confirmed at the molecular level that major adaptive responses to drought are dependent on sufficient N nutrition. Although N uptake was decreased under drought, N-use efficiency and transcription of most genes encoding N metabolism enzymes were elevated, demonstrating that active N metabolism positively contributed drought resistance and growth of C. bungei under sufficient-N conditions.

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Graphene oxide (GO) was modified by 3methacryloxypropyltrimethoxysilane (MPS) to obtain modified graphene oxide (MGO). MGO was dispersed in urushiol-formaldehyde polymer by mechanical mixing and ultrasonic dispersion, and MGO/urushiolformaldehyde polymer (UFP) coatings with different MGO contents were fabricated. The microstructure, physico-mechanical properties, and electrochemical properties of the MGO/UFP composite coatings were investigated. The results indicated that the hardness, adhesion, and corrosion resistance of the MGO/UFP composite coatings were obviously enhanced compared with the pure UFP coatings. The hardness and the adhesion grade of the MGO/UFP composite coatings with 3.5 wt% MGO (GO, 1.5 wt%, and MPS, 2.0 wt%) reached 6H and 2, respectively. Additionally, GO connected with MPS by chemical bond and the well-dispersed MGO in UFP could significantly enhance the anticorrosion performance of the UFP coatings, which could result from bending the diffusion pathway of penetrant species in the UFP coating matrix.

Panax vietnamensis Ha et Grushv. is a precious medicinal species native to the tropical forests of Vietnam. Due to habitat loss and over-harvesting, this species is endangered in Vietnam. To conserve the species, we investigated genetic variability and population structure using nine microsatellites for 148 individuals from seven populations across the current distribution range of P. vietnamensis in Vietnam. We determined a moderate genetic diversity within populations (HO = 0.367, HE = 0.437) and relatively low population differentiation (the Weir and Cockerham index of 0.172 and the Hedrick index of 0.254) and showed significant differentiation (P < 0.05), which suggested fragmented habitats, over-utilization and over-harvesting of P. vietnamensis. Different clustering methods revealed that individuals were grouped into two major clusters, which were associated with gene flow across the geographical range of P. vietnamensis. This study also detected that ginseng populations can have undergone a recent bottleneck. We recommend measures in future P. vietnamensis conservation and breeding programs.

Ca-bentonite (CB) alone and in a mixture with limestone (L), tobacco biochar (TB) and zeolite (Z) on the fixation, geochemical fractions and absorption of Cd and Zn by Chinese cabbage in smelter heavily polluted (S-HP) and smelter low polluted (S-LP) soils were investigated. The results showed that the CB + TB and CB + L + TB treatments significantly immobilized Cd up to 22.0% and 29.7%, respectively, and reduced uptake by Chinese cabbage shoot to 36.0% with CB + Z + L and 61.3% with CB + L in S-HP and S-LP soils compared with the control. The CB + Z + L + TB treatment mobilized Cd up to 4.4% and increased absorption in the shoot by 9.9% in S-HP soil. The greatest immobilization of Zn was 53.2% and 58.2% with the CB + Z + L + TB treatment, which reduced Zn uptake in the plant shoot by 10.0% with CB + L and 58.0% with CB + Z + L + TB in S-HP and S-LP soils. The CB + Z + TB and CB + TB treatments mobilized Zn up to 35.4% and 4.9%, respectively, in both soils. Furthermore, the uptake of Zn in plant shoot was observed by 59.0% and 7.9% with application of CB + Z and CB + TB treatments, respectively, in S-HP and S-LP soils. Overall, our results suggest that Ca-bentonite alone and in mixtures with different amendments can be used to reduce the phyto-extraction of Cd and Zn in Zn-smelter polluted soils.