Rhynchostylis is an epiphytic orchid belonging to the Orchidaceae family. It possesses high ornamental and economic value. In this study, based on the collection of 10 different germplasm resources from three common species of Rhynchostylis, 21 pairs of SSR polymorphic primers were selected using fluorescent-labeled capillary electrophoresis for allele variation detection. Among them, 13 primer pairs exhibited high polymorphism, resulting in a total of 47 amplified alleles. The average number of observed alleles (N_a) was 2.238, and the average number of effective alleles (N_e) was 1.860. The observed heterozygosity (H_o) of the 21 loci ranged from 0 to 0.778, with a mean of 0.421, while the expected heterozygosity (H_e) ranged from 0.148 to 0.574, with a mean of only 0.340. The Shannon index (I) ranged from 0.096 to 0.987, with a mean of 0.567. The clustering results and PCoA analyses of the 10 germplasm were consistent with the traditional botanical classification, and all the germplasm could be classified into three taxa by species. On this basis, four pairs of core primers were selected to construct a molecular ID for each germplasm. This study lays a foundation for the collection, conservation, identification, development and utilization of the germplasm resources of Rhynchostylis.

This paper reports a new record Orchidaceae genus—Vandopsis Pfitz, and two new record species—V. gigantea (Lindl.) Pfitz and Dendrolirium tomentosum (J. Koenig) in Guangdong province. The detailed morphological description, habitat distribution and color photos are provided. The findings expand the distribution range of those taxons and is of great significance to the flora study.

The sisal zebra disease, caused by fungal pathogen Phytophthora nicotianae Breda, is one of the main diseases in sisal, which seriously affects the development of sisal industry. The pathogenic mechanism is not clear up to now. In order to obtain new anti-zero disease sisal variety, Yuexi 114 and H.11648 were used as the parents to breed new offsprings. Rema No.1 is one of the backcross progenies of Yuexi 114 and H.11648. Morphological traits including leaf shape, leaf color, have/none marginal spine, apical spine type, leaf length, leaf width, thickness of leaf base, length of apical spine, and spine basal width, plant height, inflorescence shape and flower stalk height, number of pedical, flower, fruit and seed characters, number of leaf, fiber ratio were examined. Ploidy level, genome size and resistance to P. nicotianae Breda was determined by an analysis of wall removal and low permeability flame drying method, flow cytometry, and inoculating P. nicotianae Breda in field and lab respectively. Rema No.1 is characterized by the presence of gray green, fleshier and rigid, sword-leaf with wax powder on the leaf surface, 1.2-2.0 cm apical spine, none marginal spine. Leaf length, leaf width and leaf base is about 130 cm, 16 cm, and 3.5 cm, respectively. The leaves rise in a spiral arrangement around the stem. Rema No.1 is also characterized by plant height 1.8-2.5 m, flower stalk 3-7 m, paniculate inflorescence, with 20-32 pedicals, complete flower, yellow flower with 6 petals, oblong capsule, dark brown to almost black upon maturity, lunate black seeds, marginate. leaves 360-400, leaf fiber ratio 3.5%, fiber length 100 cm. The life span is 6-9 years. Rema No1 is tetraploid (2X=4n), chromosome number is between 104-118, the genome size of Rema No. 1 is 2C=11.69 pg. Rema No.1 is high resistant to Phytophthora nicotianae Breda, and would be the main cultures in high incidence area of zero leaf disease in sisal planting region.

A genus, Tolypanthus, and three species: Tolypanthus esquirolii (Lévl.) Lauener, Morus liboensis S. S. Chang and Scutellaria franchetiana Levl. from Fuyuan Shibalianshan Provincial Nature Reserve were reported as newly recorded species to Yunnan province. Voucher specimens for the reported species were preserved in the Herbarium of Kunming Institute of Botany (KUN), Chinese Academy of Sciences.

Both friable embryogenic callus and suspension cells are ideal materials for genetic and cell engineering. However, the induction of friable embryogenic callus of Hevea brasiliensis is low frequency and time-consuming, and its embryogenic competence usually decreases gradually or even completely loses with the increase of subculture times. Therefore, to quickly obtain friable embryogenic callus, establish embryogenic cell suspensions with high efficiency of somatic embryogenesis, and maintain the embryogenic competence as long as possible, are important research contents for genetic and cell engineering of H. brasiliensis. In this study, the immature anthers of H. brasiliensis clone Reken 525 was used as the explants to induce callus and establish embryogenic cell suspensions, and the effects of two long-term subculture methods-solid and liquid on the maintenance of embryogenic competence were compared and analyzed. The results showed that the yellow and compact primary callus tissue induced from anther explants on callus induction medium had a low ability for somatic embryogenesis, and was not suitable for suspension culture due to poor dispersion. After 70-80 d of culture on the medium for embryogenic callus induction, the formation of embryogenic structures and early somatic embryogenesis were observed, and bright yellow small granular friable embryogenic calli grew around them. The type Ⅰ embryogenic suspension cell line established through routine methods possessed typical characteristics of embryogenic cells, and the frequency of somatic embryogenesis was significantly higher than that of embryogenic callus tissue, but proned to callus formation during somatic embryogenesis; the type Ⅱ embryogenic suspension cell line established by screening specific embryogenic tissue and initiating with low density suspension culture was in an orderly embryonic structure observed by microscope, and its frequency of somatic embryogenesis could reach up to 100%. After two years of continuous subculture in liquid culture medium containing 2 mg/L 2,4-D, the cells were obviously aging with lower proliferation coefficient, and the ability for somatic embryogenesis was almost lost. However, the ability for somatic embryogenesis still remained at a high level after two years of continuous subculture on solid culture medium without 2,4-D but supplemented with abscisic acid (0.1 mg/L) and hydrolyzed casein (0.5 g/L). The type Ⅱ embryogenic suspension cell line could provide high-quality, sufficient and relatively stable material sources for genetic transformation and protoplast culture of Hevea brasiliensis in the long term.

The effects of long-term nutrient deficiency on cassava agronomic characters, yield and starch content were studied to provide scientific basis for fertilization of continuous cropping. In this study, experimental materials in 2019 to 2021 (continuous cropping in 28th-30th years) were selected from the time axis of long-term fertilization trials. CK (with NPK), –N (without N), –P (without P), –K (without K) combined with two cassava varieties SC205 and SC124 were selected. The SPAD value, plant height, stem diameter and starch content, yield, starch yield of the fresh storage root (FSR) were measured and evaluate. Compared to CK, –N and –K significantly reduced plant height, and –N, –P and –K significantly reduced stem diameter of cassava. Meanwhile, –K significantly reduced SPAD value of leaves. Test of between-subjects effect showed that, variety or fertilization had significant effects on agronomic characters, but the interaction effect between them was not significant. The starch content of FSR, compared to CK, –N significantly improved in 2021. –K significantly reduced, the three-year average decrease was 14.2%. Compared to CK, –N, –P and –K significantly reduced the yield, starch yield of FSR, storage root number per plant (SRNPP) and weight per storage root (WPSR). The yield of FSR reduced by more than 40.0% under different nutrient deficiency, while the yield effects were insignificantly different among nutrient deficiency treatments. The starch yield of FSR under -K decreased by 53.3%, the decrease was significantly higher than that of –N and –P. The correlation analysis showed that yield, starch yield of FSR were extremely significantly positively correlated with the SRNPP, and significantly positively correlated with the WPSR. –N, –P and –K significantly inhibited cassava growth. N was the primary limiting factor for cassava fresh storage root yield in the early stage of continuous cropping, followed by K, but P effect was not obvious. With the extension of continuous cropping years, the effects of K and P effect gradually became more significant, and N, K became the main limiting factors, then there was no significant difference on the fresh storage root yield effect among N, P and K, there were equally important.

Rubber tree is important in global rubber production. In order to reveal the effects of microelement fertilizer combined with absorption enhancer on the growth of rubber tree seedlings, and lay a foundation for the innovation of microelement fertilizer application technology of rubber tree. In this study, the single application of microelement (W), the combination of absorption enhancer formula 1 and microelement fertilizer (C₁+W), and the combination of absorption enhancer formula 1 and microelement fertilizer (C₂+W) were treated with ultra-pure water as the control to investigate the effects of compound microelement fertilizer application alone or combined with absorption enhancer on the growth, dry matter accumulation, photosynthesis, root development and nitrogen distribution of rubber tree seedlings and their mechanisms. The results showed that micronutrient fertilizer could increase the dry matter accumulation of roots, stems, and leaves in rubber seedlings, thereby increasing the individual fresh weight, dry weight, and dry to fresh ratio. Among them, C₂+W increased the fresh and dry weight of plants by 4.18 and 5.89 times, which is much greater than those of C₁+W and W. The accumulation of dry matter in rubber seedlings by microelements fertilizers was positively correlated with root length, root surface area, and root volume, and with chlorophyll content, transpiration rate, and net photosynthetic rate of rubber seedlings. The root development and photosynthesis were positively correlated with nitrogen accumulation in various organs of crops, soluble protein content, nitrate reductase activity (NR), glutamine synthase activity (GS), and glutamate dehydrogenase activity (GDH) in leaves. Notably, the single application of microelements fertilizer had no significant effect on NR activity, indicating that W had a weak effect on nitrogen assimilation in the reduction of nitric acid to nitrite. Significantly, the single application of microelements fertilizer (W) had no significant effect on NR activity, indicating that microelements fertilizer had a weak effect on nitrogen assimilation in the reduction of nitric acid to nitrite. In summary, microelements fertilizers and absorption enhancer enhance the connection between C assimilation and N metabolism processes in rubber seedlings, promote the growth and development of rubber seedlings. Considering the wide and thick leaves of rubber, tight cells, and thick stratum corneum, subsequent research should continue to screen more suitable absorption enhancer and optimize the combination with microelements.

In order to investigate the effects of intercropping Centrosema pubescens or Grona styracifolia on soil physicochemical properties, microbial community structure and diversity in the litchi orchard, soil samples from 0 to 40 cm depth between litchi tree rows were collected under intercropping with either C. pubescens or G. styracifolia. Physicochemical factors such as soil organic matter, total nitrogen, total phosphorus, total potassium, nitrate nitrogen, ammonium nitrogen, available phosphorus, available potassium and pH were measured. In addition, Illumina NovaSeq sequencing platform was used for 16S amplicon sequencing to analyze the microbial communities in the soil under intercropping with C. pubescens or G. styracifolia in the litchi orchard. The results showed that the nutrient content in the 0-20 cm soil layer was generally higher than that in the 20-40 cm soil layer. In the 0-20 cm soil layer, the C. pubescens intercropping treatment increased soil organic matter by 7.06%, total nitrogen by 8.70%, and ammonium nitrogen by 103.29%, compared to the control. In the intercropping treatment with G. styracifolia, soil ammonium nitrogen increased by 69.41%, nitrate nitrogen increased by 32.48%, available phosphorus increased by 112.78%, and available potassium increased by 9.44%, compared to the control. In the 20-40 cm soil layer, the C. pubescens intercropping treatment increased soil ammonium nitrogen by 114.58%, but decreased available potassium by 48.07%, compared to the control. In the intercropping treatment with G. styracifolia, soil nitrate nitrogen decreased by 15.07%, while available phosphorus increased by 105.43% and available potassium increased by 32.60%, compared to the control. In terms of microbial diversity, the indices in the 0-20 cm soil layer were generally higher than those in the 20-40 cm soil layer. In the 0-20 cm soil layer, the ACE index and Chao1 index in the C. pubescens intercropping treatment were decreased by 7.65% and 7.68%, respectively, compared to the control. In the 20-40 cm soil layer, the ACE index and Chao1 index in the intercropping treatment with G. styracifolia were increased by 6.93% and 6.74%, respectively, compared to the control. In terms of soil microbial community structure, the dominant phyla in all soil samples were Acidobacteria, Chloroflexi, Proteobacteria, Firmicutes, and Actinobacteria, while the dominant genera were Gp2, Gp13, Bryobacter, Candidatus Solibacter and Bathyarchaeia within the Acidobacteria phylum. After intercropping, the relative abundance of Thaumarchaeota, Nitrospirae, Verrucomicrobia, Gp2, Gp13 and Bryobacter increased. Redundancy analysis indicated that pH, total potassium, total phosphorus, and available potassium were the main physicochemical factors affecting soil microbial community structure. In summary, the results of this study would provide a theoretical basis for intercropping with C. pubescens or G. styracifolia in litchi orchards.

As an important component of terrestrial soil carbon reservoirs, the agricultural soil organic carbon pool is greatly influenced by cultivation patterns. Coffee, one of the major economic crops in tropical regions of the world, a minor changes of its cultivation pattern can significantly affect the carbon balance of terrestrial ecosystems. Mulching cultivation is one of the traditional cultivation models for coffee, but its impact on the organic carbon composition of coffee plantation soil is still unclear. Therefore, based on the previous research of our team using coffee peel and leaf litter as substitutes for traditional mulch to cultivate coffee, four mulching treatments were set up in this study: uncovered coffee waste (CK), coffee leaf litter mulch (L), coffee peel mulch (P), and both coffee peel and litter mulch (PL). Soil micro-environment, microbial community diversity and biomass, organic carbon fractions, and other indicators were monitored in the coffee plantation, and the intrinsic relationships between soil micro-environment, microbial community structure, and organic carbon fractions were analyzed to investigate the effects of coffee waste cover on soil components and the key driving factors. The results showed that coffee waste cover did not affect the content of soil organic carbon (SOC), heavy fraction organic carbon (HFOC), and dissolved organic carbon (DOC), while coffee peel and litter mulch significantly increased the content of soil light fraction organic carbon (LFOC) by 13.31% and 14.12%, respectively. Coffee waste mulch did not affect soil micro-environment indicators or microbial diversity. Coffee peel cover significantly increased soil microbial biomass by 14.05%, and increased the relative abundance of Proteobacteria and Firmicutes by 18.60% and 80.77%, respectively, while reducing the abundance of Cyanobacteria by 70.14%, but had little impact on soil fungal community. Coffee litter mulch significantly increased the relative abundance of Proteobacteria and Firmicutes by 14.43% and 57.63%, respectively, while reduced the abundance of Cyanobacteria by 73.43%, and significantly increased the relative abundance of dominant fungi Ascomycota by 14.79%. The reason why coffee waste mulch did not affect the soil organic carbon content is mainly attributable to the insensitivity response of HFOC content to coffee waste mulching. The increase of microbial biomass and the increase relative abundance of Firmicutes are the main reasons to enhance the excitation effect caused by external organic carbon input, thus significantly increasing the content of soil LFOC content. The short-term mulch of coffee waste significantly increased the content of soil LFOC content, which is contribute to improve the soil carbon storage of coffee plantations and optimize the green and low-carbon production mode of coffee.

Aquilaria sinensis (Lour.) Gilg is a resin containing wood in the genus Aquilaria or Gyrinops. Among them, agarwood essential oil (AEO) is the main functional active component of agarwood, which has good neuroprotective effect and is often used to soothe the body and mind, relieve anxiety and depression, and treat insomnia. A large number of studies have shown that the chemical composition of AEO mainly includes chromones, sesquiterpenoids, aromatics, fatty acids and other compounds, among which 2-(2-phenethyl) chromone and sesquiterpenoids are the characteristic components. However, there is no clear standard for AEO classification and quality testing, and the quality of AEO is uneven, which greatly affects the development of agarwood industry. The efficacy of AEO is closely related to its chemical composition. The chemical composition and content of AEO obtained from different raw materials (species, origin, induction methods and time) and different extraction methods (hydro-distillation, supercritical fluid carbon dioxide extraction, solvent extraction) are quite different. Therefore, it will be the direction of future research to establish a sound grading and quality testing standard of AEO, and reveal the internal relationships of the chemical composition of AEO with the raw materials and extraction methods. In addition, due to the increasing demand for agarwood, the wild population of agarwood species has declined rapidly, resulting in the depletion of wild resources. However, with the popularization of artificial cultivation and induction methods, the yield of agarwood has been greatly improved, which provides a research basis for further research on AEO. This article reviews the chemical components of AEO from different sources and their application prospects in neuroprotective effects, and analyzes the problems existing in the current research of AEO.