In order to study the changes of cassava yield, quality, photosynthetic performance and soil enzyme activities under cassava intercropping mode of muskmelon, and to provide theoretical basis for improving the cultivation technology of cassava intercropping muskmelon in Changsha, cassava (Nanzhi 199) and muskmelon (Xiangtian thin crisp) were used as the experimental materials, cassava monoculture (CK) was used as the control, and three planting densities (T₁, T₂, T₃, plant spacing of 0.5, 0.7, 0.9 m) of muskmelon in cassava intercropping were used as treatments. Compared with monoculture cassava, the number of tuber per plant, dry matter percentage and starch content of cassava were not significantly changed under intercropping treatment, but the yield per plant, economic yield, soluble protein and vitamin C content of cassava increased under intercropping treatment. The effects of each treatment on cassava yield and quality were in the order of T₂>T₃>T₁>CK. The photosynthetic capacity of cassava leaves in intercropping mode significantly increased, and the net photosynthetic rate (P_n) of cassava leaves in root tuber formation and expansion stage was significantly higher than that of monoculture treatment. The P_n of cassava leaves under T₂ treatment was significantly higher than that under other treatments, and the intercropping treatment had significantly higher intercellular CO₂ concentration (C_i), stomatal conductance (G_s) and transpiration rate (T_r) than those under monoculture treatment. With the growth of cassava plants, the activity of sucrase in soil showed a trend of decreasing first and then increasing, urease showed a trend of increasing first and then decreasing, while acid phosphatase and catalase showed a trend of decreasing gradually. The activity of sucrase, acid phosphatase and catalase in soil was significantly promoted by intercropping at different stages, but had little effect on urease activity. The activity of sucrase, acid phosphatase and catalase in soil of T₂ treatment was significantly higher than those of monoculture treatment at the expansion and maturity stages of cassava roots. In conclusion: Compared with cassava monoculture, cassava intercropping model improved cassava photosynthetic performance and soil fertility level, so as to improve the economic yield and quality of cassava. The optimal cultivation model with two rows of cassava intercropping and one row of melon with a distance of 0.7 m was suitable for the cassava intercropping model in Changsha.

The object of this study was to investigate the growth, photosynthesis and carbohydrate of 'Shatangju' mandarin grafted on various rootstocks. The tree vigor, net photosynthesis (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), leaf chlorophyll, carbohydrates of 'Shatangju' mandarin budded on Ichang papeda (Citrus ichangensis Swingle), Trifoliate orange [P. trifoliate (L.) Raf.], 'Shatangju' mandarin (C. reticulata Blanco cv. Shatangju), Fragrant orange (C. junos Sieb.ex Tanaka), Rough lemon (C. jambhiri Lush) were evaluated. The scion height, trunk cross-section area (TCSA), leaf area and shoot length of 'Shatangju' on Fragrant orange and Rough lemon were significantly bigger than that on the Ichang papeda. The lowest affinity was found with Ichang papeda, which showed the highest rootstock/scion ratio (2.08). Total leaf chlorophyll content range from 0.85 mg/g FW to 1.40 mg/g FW, significantly higher leaf chlorophyll content was found in trees grafted on Rough lemon and Trifoliate orange than other grafting combinations. Trees on Fragrant orange had the highest net photosynthesis (P_n), transpiration rate (T_r), stomatal conductance (G_s), while Ichang papeda induced the lowest photosynthesis rates. As the production of CO₂ photosynthesis, high photosynthesis efficiency led to higher carbohydrate (total soluble sugar, sucrose, reduced sugar content) in 'Shangtangju' leaves budded onto Fragrant orange and Rough lemon rootstocks compared to trees on the Ichang papeda. The data confirmed that the low affinity of Ichang papeda rootstock and 'Shatangju' mandarin scion combination caused the lower photosynthesis efficiency and tree vegetative growth. The Fragrant orange rootstock could be a suitable candidate for the 'Shangtangju' mandarin production in citriculture.

The purpose of the study is to ascertain the molecular mechanism of the albino mutation of Aristaloe aristata, screen related functional genes, and provide basis for the breeding. The Illumina HiSeq sequencing platform was used to carry out transcriptome high-throughput sequencing for normal leaf color seedlings WT, albino mutant ls and qj. The sequencing results were annotated and analyzed. A total of 67.72 Gb clean data was obtained. A total of 122 665 unigene annotation results were obtained from functional annotation. For the analysis of Unigenes expression, a total of 914 differentially expressed genes (DEGs) in ls were screened out, among them, 453 genes were up-regulated and 461 down-regulated. There were 1851 differentially expressed genes (DEGs) screened in qj, of which up- and down-regulated genes were 868 and 983, respectively. According to a comparative analysis of GO functional enrichment and KEGG metabolic pathway, it was found that in the two mutant strains, there were many DEGs enriched in pigment accumulation, cell wall organization or biogenesis, cell wall, cell periphery, hydrolase activity of hydrolyzing o-glycosyl compounds, hydrolase activity acting on glycosyl bonds, and biosynthesis pathway of secondary metabolism, while the DEGs related to photosynthesis were not significantly enriched. In the pathway related to photosynthesis, the expression of porA and cab13 were significantly down-regulated in mutant ls, and porA and moda were significantly down-regulated in mutant qj. The results of real-time reverse transcriptase PCR (qRT-PCR) confirmed the consistency of the relative expression trend and the transcriptome data of these genes. The expression of the key gene, porA, which was down-regulated in both mutants, was assumed to be a key factor in the formation of albino seedlings of A. aristate since it was found to affect the enzymatic reaction of protochlorophyllin ester to chlorophyllin ester and thereby affecting the chlorophyll synthesis of the two mutants. Our study explored the transcriptome information of albinism mutation of A. aristate, screened the key genes with significant expression differences, and would provide an important theoretical basis for further exploring the molecular mechanism of albinism mutation of A. aristate.

An early-maturing, high-yield, high-starch, wide-adaptability cassava cultivar was bred in Guangxi for fresh consumption or further processing. A newly bred F₁ progeny of crossing between the high-yield, XX048 as the female parent and the high-starch NZ199 as the male parent was generated by artificial pollination and induction through prediction of graft breeding. After seedling selection, single row and a series of primary, intermediate, and advanced tests as well as regional and production trials, Guire No. 13 (GR13) was selected. As showed in the several years trial, GR13 delivered an average tuber yield of 47.06 t/hm², starch content was 32.0%, which was 22.93% and 21.48, 3.74 and 5.30 percentage point higher than that of NZ199 and SC205; Dry matters content of 45.2%, which was 4.7 and 7.5 percentage point higher than that of NZ199 and SC205, and HCN content was 25.7 mg/kg, lower than that of NZ199 and SC205; a rich content of nutrients (based on FW), such as 0.73% on crude fiber, 42.87 mg/hg on vitamin C, 0.75 g/hg on protein, 3% on total sugar, 1.1% on soluble sugar. The early-maturing (over 27.0% on starch content after planted 180 days), high and stable yield GR13 with wide-adaptability was resistent to drought, cold and mites, and its leaves did not fall off easily. It could be adequately cultivated in current cassava-producing areas in Guangxi, Jiangxi, and Yunnan provinces for either fresh consumption, further processing, or as a raw material for manufacturing starch products.

Mangifera indica Linn. is a tropical and subtropical evergreen tree fruit, sweet fruit, rich nutrition, meat smooth and juicy, which is rich "tropical fruit king" reputation. In order to speed up the molecular identification of mango cultivars (lines), five mango cultivars (Red Ivory Mango, Jinhuang Mango, Red Mango No. 6, Red Jade Mango, Nan Doc Mai No. 4 Mango) with different phenotypic characteristics were selected from 19 test materials to screen SSR marker primers. The primers with better polymorphism were obtained by PAGE electrophoresis. Then, the primers were labeled with 5'-end modification with HEX and FAM fluorescent labels. The size of the amplified fragments were detected by capillary electrophoresis, and the polymorphic sites of each pair of primers were coded by numbers and letters. Finally, DNA fingerprint and DNA molecular ID card of mango were constructed by capillary electrophoresis. The results show that nine pairs of primers with good polymorphism were screened from the developed SSR primers from 115 pair primers through PCR amplification and PAGE electrophoresis. The primers were named M9, M15, M35, M40, M53, M59, M101, M102, and M103. After capillary electrophoresis detection and data analysis, bar code DNA molecular identification and quick response code DNA molecular identification of the mango cultivars (lines) were obtained combined with "number+letter" processing. For example, the fingerprint code of Jinhuang Mango is 9EE9F8933, the fingerprint code of Qianshan Mango No. 2 is H6F7564IC, and the fingerprint code of Qianshan Mango No. 4 is 3DGE47279. Finally, with the fingerprint code and basic information of 19 materials as the carrier, barcode DNA molecular ID and two-dimensional code DNA molecular ID were generated by online barcode generation program and two-dimensional code generation program. This study laid a foundation for standardizing the construction of molecular identification database of DNA of mango, and could provide data reference for mango genetics and breeding and excellent gene excavating.

Podocarpus macrophyllus is a common garden ornamental and greening tree species in southern China, with high economic and medicinal value. To study the physiological response of nitrogen addition under different phosphorus environments to P. macrophyllus seedlings, two-year-old P. macrophyllus seedlings were used as the material, two soil phosphorus conditions including low additional phosphorous (0.26 g/plant), high phosphorus addition (1.08 g/plant), three nitrogen addition levels including low nitrogen addition (0.53 g/plant), medium nitrogen addition (1.06 g/plant) and high nitrogen addition (2.12 g/plant) were set up and analyzed the differences of physiological characteristics, chlorophyll content, gas exchange parameters and leaf nutrient content of P. macrophyllus seedlings in each treatment group. Nitrogen addition increased the activity of POD, and high concentration nitrogen fertilizer decreased the activity of SOD. The application of nitrogen fertilizer in a low phosphorus environment increased soluble sugars and soluble proteins, decreased MDA and Pro. Soluble protein and soluble sugar accumulation decreased in high nitrogen and phosphorus environment, but MDA and Pro increased. The chlorophyll content of P. macrophyllus seedlings was the highest under medium concentration nitrogen treatment. The addition of nitrogen in low phosphorus environment increased the P_n, T_r and G_s of P. macrophyllus seedlings, while C_i (intercellular CO₂ concentration) of P. macrophyllus seedlings decreased. The P_n, T_r and G_s were the highest and C_i was the lowest in the medium nitrogen treatment group in high phosphorus environment. P_n, T_r and G_s decreased, and the C_i increased in the high nitrogen concentration and high phosphorus environment. The same change trend of P_n and T_r and correlation analysis showed that P_n of P. macrophyllus seedlings was mainly limited by stoma factors. Nitrogen addition promoted the increase of leaf nitrogen content in low phosphorus environment, but decreased the leaf nitrogen content in high phosphorus environment. Nitrogen addition limited the accumulation of phosphorus in the leaves of P. macrophyllus seedlings, but the increase of soil phosphorus content promoted the accumulation of phosphorus content in leaves. The increase of phosphorus fertilizer concentration increased the enzyme activity of P. macrophyllus seedlings under different nitrogen treatments. The increase of nitrogen fertilizer concentration decreased the content of MDA and Pro, and the content of soluble sugar and soluble protein increased in the low nitrogen and high nitrogen treatment groups. The increase of phosphorus fertilizer concentration increased the content of MDA and Pro, and the content of soluble sugar and soluble protein decreased in the high nitrogen treatment groups. Increasing the concentration of phosphate fertilizer promoted the chlorophyll content and photosynthetic efficiency of low and medium nitrogen treatment groups, while increasing the concentration of phosphate fertilizer decreased the chlorophyll and photosynthetic efficiency.

At present, the safety of natural rubber resources in China is becoming increasingly prominent. It is of great theoretical and practical significance to carry out dynamic monitoring of natural rubber production. Based on the long-panel data set, the spatial distribution characteristics, and evolution of natural rubber in China from 1995 to 2020 were studied by using production scale index, production concentration index, production gravity analysis method, efficiency advantage index, scale advantage index and aggregated advantage index in this paper. The results showed that the distribution of natural rubber production in China gradually concentrated to Yunnan and Hainan from 1995 to 2020, and the production concentration index of Yunnan and Hainan reached 97.87% in 2020. Yunnan surpassed Hainan to become the most comparative advantage rubber planting area in China, and Hainan belonged to the comparative advantage area. At the same time, the spatial center of gravity moved to the northwest obviously, and the comparative disadvantages of Guangdong, Guangxi and Fujian were more prominent. In the future, the spatial statistical analysis method based on multi-factor and multi-scale would become an important development direction of the research on the spatiotemporal evolution and prediction of natural rubber production distribution.

Streptomyces catenulae XG40 is a biocontrol strain with antagonism to pathogens of pomelo black spot. In this study, the whole-genome sequence of S. catenulae XG40 was completed by the third generation sequencing platform PacBio Sequel. Three contigs were obtained, including one chromosomal DNA and two plasmid DNA. The total length of the genome sequencing was 9 772 324 bp with 70.58% GC content, and 8074 protein-coding genes were predicted which were accounted for 96.41% of all genes. Forty-six putative secondary metabolite biosynthetic gene clusters were found in the genome using the online antiSMASH software, among twenty-four PKS and NRPS, which were accounted for 52.17% of all gene clusters. Seven putative gene clusters showed 100% similarities to known gene clusters: desferrioxamin B, pristinol, neoantimyci, 2-methylisoborneol, nigericin, ectoine, geosmin gene clusters. Four putative gene clusters showed more than 80% similarities to known gene clusters: miharamycin A/B, SW-163C/E/F/G/UK-63598, gilvocarcin V, coelibactin. Clusters analysis showed that S.catenulae XG40 had certain ability of the biosynthesis of nigericin and gilvocarcin V with antibacterial activity. The analysis of synteny indicated that genome insertion, deletion, rearrangement and translocation happened among the genomes of S. catenulae XG40, S. rhizosphaericus DSM 41760, S. malaysiensis DSM 14702, melanosporofaciens DSM 40318 and S. himastatinicus ATCC 53653. This research would provide a theoretical basis for further discovering biocontrol potential of XG40 and the secondary metabolites for agricultural biological control.

Cymbidium sinensis is a typical fragrant orchid variety with high economic and ornamental value. HS-SPME/GC-MS was used to analyze the volatile components of different flower organs in C. sinensis. Seven categories and 54 volatile components were detected, mainly composed of 21 aldehydes, 12 alcohols, 10 ketones, 5 benzenes, 2 furans, 2 acids and 2 terpenoids. There were 48 compounds presented in four different flower organs, including petals, sepals, labellums, and pistil columns, including 19 aldehydes, 10 alcohols, 9 ketones, 5 benzenes, 2 terpenoids, 2 furans and caproic acid. There were three components in petals, sepals and pistil columns, only two components were detected in sepals, and Acrolein was only detected in pistil columns. The results showed that there were significant differences in the volatile matter and content in different floral organs of flowers. A total of 49 volatile substances were detected in sepals, with the highest content reaching 99 106.15 μg/L, accounting for 35.88% of the total volatile organic compounds. Among which the highest content was cyclopentyl formaldehyde, which had the camphor flavor of mint. 51 volatile compounds were detected in the petals, with a substance content of 56 571.48 μg/L, accounting for 20.48% of the total volatile organic compounds, with the highest content being 1-penten-3-ol, which had a fruity aroma. A total of 48 volatile substances were detected in the labellum flap, with the lowest substance content of 41 645.32 μg/L, the proportion of total volatile organic compounds was 15.08%, among which the highest content of volatile substance was cyclopentyl formaldehyde. A total of 51 volatile compounds were detected in the pistil column, with a content of 78 868.68 μg/L, accounting for 28.56% of the total volatile organic compounds, with the highest content being hexanal, which presented a fresh oil, green grass, and apple aroma. Through principal component analysis, it was found that among the four flower organs, there was little difference between the lip and petal, while the pistil column had a greater difference from other organs, and the sepals also had a greater difference from other organs. Glutaraldehyde, hexanal, E-2-pentenal, E-2-hexenal, cyclopentyl formaldehyde, E-2-heptaneal, 1-penten-3-ol, E-2-penten-1-ol were the main volatile components released by floral organs. During the peak flowering period, the sepals of the flowers were the main floral organs that released volatile components, and there were significant differences in the content of floral aroma components among different floral organs.

In order to understand the C, N and P eco-chemometric characteristics of different tree age groups, the coffee from the Manxieba Xiaoaozi Nanpingzhen a Coffee Estate in Pu'er Simao District was studied in four tree age groups: 1 a, 7 a, 10 a and 20 a, the C, N, and P levels in coffee leaves and soil were determined, as well as the chemometric ratio between them. The N and P content of coffee leaves was proportional to the age of the tree, gradually increasing with the age of the tree, inversely proportional to the C content, gradually decreasing with the age of the tree. The differences in N and P content of coffee reached significant levels (P<0.05), and the chemometric ratios C∶N and C∶P decreased with tree age, among which C∶P was significantly different in different tree ages (P<0.01). Leaf N∶P threshold analysis found that the leaf N∶P ratio was less than 14 in all four tree age segments, indicating that the growth of coffee was mainly limited by N elements. There was significant variability (P<0.05) in SOC content between tree age groups, with 7 a coffee having the highest C, N and P content. The mean values of C, N and P content were slightly higher for 0-10 cm soils than for 10-30 cm soils and 9.79 for 0-10 cm soils than 6.87 for 10-30 cm soils. The range of C∶P variation for coffee was 11.51-46.80 for 0-10 cm soils and 4.53-20.82 for 10-30 cm soils, with large inter-soil variations. The range of N∶P variation was 1.00-5.12 and 0.81-2.08 for different soil layers, respectively. The correlation showed that N∶P and P elements were significantly correlated and P element was the main cause of C∶N variation. From the correlation analysis, coffee leaf C was significantly negatively correlated with N, P (P<0.05), leaf N was extremely significantly positively correlated with C∶N, C∶P (P<0.01) and leaf P was extremely significantly negatively correlated with C∶P (P<0.01). The SOC and TN of different soil layers were positively correlated (P<0.05), and the C, N, and P of the blade were not correlated with the TOC, TN, and TP of the soil, and the ratio of measurements was rarely correlated. It can be seen from the above that the SOC, TN and TP of coffee soil were relatively low, the soil was mainly limited by N nutrients. In addition, the absorption of N and P by coffee leaves had a synergistic effect, and there was a broad quantitative coupling relationship between coffee leaves and soil elements.