Fragrant rosewood (Dalbergia odorifera T.C. Chen) is a highly-valued species suffering from vulnerability due to over-development for wood and medicine. In this study, Fragrant rosewood seedlings were cultured with chitosan oligosaccharide (CO) addition at rates of 0 and 1/800 (v/v) under artificial lightings by 200-W high-pressure sodium (HPS) lamps and 280-W light-emitting diode (LED) panels for a 15 h daily photoperiod and a natural illumination as the control. The LEDs were designed to emit lights in 85% of red (600–700 nm), 15% of green(500–600 nm), and 5% of blue (400–500 nm). The height of artificial lightings was elevated every five to seven days to keep the mean photosynthetic photon flux density (PPFD) of 72–73 µmol m⁻² s⁻¹ of artificial lighting at shoot-tips. Seedlings under LED lighting with CO addition had the greatest diameter growth and leaf biomass, as well as the highest nutrient utilization and evaluated quality, while those under HPS lighting had a higher stem sugar concentration but unchanged shoot growth and biomass compared to the control. In conclusion, we recommend Fragrant rosewood seedlings to be cultured with CO addition under LED lighting to efficiently promote synthetic quality and nutrient utilization.

The scientific management of salinized agricultural lands and the use of undeveloped saline lands to ensure food security have become one of the most urgent tasks nowadays. Biochar contains rich carbon (C) and functional groups, and processes high alkalinity, porosity, and specific surface area (SSA). Thus, it has been widely used as an effective organic conditioner in acidic or neutral soils to improve their fertility. However, so far, the impacts of biochar application on properities of saline soils and the underlying mechanisms remain unveiled. Therefore, in this study, we focus on the investigation of the impacts of biochar on the physical, chemical, and biological properties of saline soils. We found that biochar could: (1) decrease soil bulk density (BD), increase soil porosity, promote the formation of soil aggregation and enhance the leaching of soil salts; (2) increase the cation exchange capacity (CEC) of soil, decrease the salinity of soil through ion exchange and adsorption; (3) directly act as the nutrient supplements, indirectly adsorb water and nutrients or improve nutrient availability (e.g., soil organic carbon (SOC) turnover and sequestration, nutrient cycling); and (4) improve the structure and functioning of the soil microbial community and therefore indirectly impact the C, nitrogen (N) and phosphorus (P) cycling in soil systems. However, these impacts heavily depend on the properties, the concentration of the biochar added to the soil, and the type and location of the soil. In fact, some studies have shown that the addition of biochar in soil could even increase the salinity of saline soils. Another issue is the lack of long-term and large-scale field experiments regarding the impact of biochar addition on properties of saline soils. Therefore, future studies should focus on long-term field experiments with the combination of traditional soil analytical methods and mordern molecular techniques (e.g., high-throughput sequencing, macro-genomics, and metabolomics) to comprehensively reveal the response mechanism of physicochemical properties and microbial characteristics of saline soils to exogenous biochar. Our study can provide a scientific foundation for the practical agricultural production and ecological management of biochar.

Background: Mangroves possess substantial ecological, social, and economic functions in tropical and subtropical coastal wetlands. Kandelia obovata is the most cold-resistance species among mangrove plants, with a widespread distribution in China that ranges from Sanya (18° 12′ N) to Wenzhou (28° 20′ N). Here, we explored the temporal variations in physiological status and transcriptome profiling of K. obovata under natural frost conditions at ~ 32^oN, as well as the positive role of exogenous abscisic acid (ABA) in cold resistance. Results: The soluble sugar (SS) and proline (Pro) functioned under freezing stress, of which SS was more important for K. obovata. Consistently, up-regulated DEGs responding to low temperature were significantly annotated to glycometabolism, such as starch and sucrose metabolism and amino sugar and nucleotide sugar metabolism. Notably, the top 2 pathways of KEGG enrichment were phenylpropanoid biosynthesis and flavonoid biosynthesis. For the antioxidant system, POD in conjunction with CAT removed hydrogen peroxide, and CAT appeared to be more important. The up-regulated DEGs responding to low temperature and ABA were also found to be enriched in arginine and proline metabolism, starch and sucrose metabolism, and peroxisome. Moreover, ABA triggered the expression of P5CS and P5CR, but inhibited the ProDH expression, which might contribute to Pro accumulation. Interestingly, there was no significant change in malondialdehyde (MDA) content during the cold event (P > 0.05), suggesting foliar application of ABA effectively alleviated the adverse effects of freezing stress on K. obovata by activating the antioxidant enzyme activity and increasing osmolytes accumulation, such as Pro, and the outcome was proportional to ABA concentration. Conclusions: This study deepened our understanding of the physiological characters and molecular mechanisms underlying the response of K. obovata to natural frost conditions and exogenous ABA at the field level, which could provide a sound theoretical foundation for expanding mangroves plantations in higher latitudes, as well as the development coastal landscape.

Forest fires are a major natural calamity that inflict substantial harm on forest resources and the socio-economic landscape. The eastern region of China is particularly susceptible to frequent forest fires, characterized by high population density and vibrant economic activities. Precise forecasting in this area is essential for devising effective prevention strategies. This research utilizes a blend of kernel density analysis, autocorrelation analysis, and the standard deviation ellipse method, augmented by geographic information systems (GISs) and deep-learning techniques, to develop an accurate prediction system for forest-fire occurrences. The deep-learning model incorporates data on meteorological conditions, topography, vegetation, infrastructure, and socio-cultural factors to produce monthly forecasts and assessments. This approach enables the identification of spatial patterns and temporal trends in fire occurrences, enhancing both the precision and breadth of the predictions. The results show that global and local autocorrelation analyses reveal high-incidence areas mainly concentrated in Guangdong, Fujian, and Zhejiang provinces, with cities like Jiangmen exhibiting distinct concentration characteristics and a varied spatial distribution of fire occurrences. Kernel density analysis further pinpoints high-density fire zones primarily in Meizhou, Qingyuan, and Jiangmen in Guangdong Province, and Dongfang City in Hainan Province. Standard deviation ellipse and centroid shift analysis indicate a significant northward shift in the fire-occurrence centroid over the past 20 years, with an expanding spatial distribution range, decreasing flattening, and relatively stable fire-occurrence direction. The model performs effectively on the validation set, achieving an accuracy of 80.6%, an F1 score of 81.6%, and an AUC of 88.2%, demonstrating its practical applicability. Moreover, monthly fire zoning analysis reveals that high-incidence areas in spring and winter are mainly concentrated in Guangdong, Fujian, Zhejiang, and Hainan, while autumn shows widespread medium-incidence areas, and summer presents lower fire occurrences in most regions. These findings illustrate the influence of seasonal climate variations on fire occurrences and highlight the necessity for enhanced fire monitoring and prevention measures tailored to different seasons.

Green bamboo (Dendrocalamopsis oldhami) represents a crucial Asian grass with medical and edible value. However, the unpalatable flavor of emerging D. oldhami bamboo shoots has reduced consumer preference. The distinct flavor of bamboo shoots could potentially be attributed to the accumulation of differential metabolites linked to variations in bamboo shoots maturation, leading to a characteristic taste. In this study, to explore the molecular mechanisms underlying the formation of the flavor characteristics in bamboo shoots, we performed a joint transcriptomic and metabolomic analysis on the principal flavor components of D. oldhami (L) and D. oldhami ‘Hualvzhu’ (HL) bamboo shoots harvested at two developmental stages, unemerged and after emerging from the soil. Physiological analysis showed that HL presented a higher water content, lower lignin content, lower flavonoids content, a lower bitterness scoring value, and a higher sucrose content compared to L. LC-MS/MS analysis identified 23,064 primary-level differential metabolites from four comparison groups, and the differential accumulation patterns of ascorbic acid and sucrose were found to cause flavor differences. GO and KEGG enrichment analysis of the transcriptomic data demonstrated that ‘Biosynthesis of secondary metabolites’ and ‘Starch and sucrose metabolism’ were the major enrichment pathways. The expression levels of GLDH, L-galDH1, and GME1 were positively correlated with ascorbic acid accumulation, whereas those of SPS1, SPP1, and SPP2 were positively correlated with sucrose accumulation. Additionally, transcription factors like AP2/ERF, NAC, and GRAS were potentially involved in the biosynthesis of ascorbic acid and sucrose. Overall, our findings firstly uncovered the flavor formation mechanism of D. oldhami bamboo shoots, offering a theoretical basis for industrial growth.

Valuable trees are frequently taken from their original habitat and introduced to a different location in the pursuit of better economic development. Global climate change imposes a higher probability of warm spells during chilly seasons; these may increase the threat posed by frost to newly introduced, valuable species. In this study, Dalbergia odorifera was cultured as a valuable tree species that was introduced from an original provenance in Sanya (1° N) to the northern mountains in Pingxiang (22° N), Guangzhou (23° N), Zhangpu (24° N), Xianyou (25° N), and up to the northernmost limit in Wenzhou (28° N). Seedlings of these six provenances were tested in a field study conducted in Wenzhou (control) to examine their resistance to local frost stress and to detect the driving forces related to meteorological factors in the winter–spring period of 2015–2016. The leaves sampled over seven days exhibited the typical characteristics of frost impairment. The daily maximum temperature delivered warm spells, increasing by ~7 °C. The daily minimum temperature (−4.3 to −2.0 °C) did not reach freezing point until the early spring of 2016. The controlled seedlings showed lower malondialdehyde content than those from the southern locations, and no mortality occurred. Invisible frost stress was caused by low nitrogen utilization during the earlier stages during warm spells, as well as damage to membrane integrity during the later stage when the minimum temperature suddenly declined. A warm spell was found to impose a negative driving force five days before a sudden chill, which led to frost having an impact on superoxide accumulation and electrical leakage. We conclude that the D. odorifera seedlings that dwell effectively in Wenzhou obtained stronger resistance to local frost stress than those from the southern locations. Low cell membrane integrity and high electrical leakage in leaf cells accounted for the frost damage.