Root exudates are one of the important sources of plant autotoxic substances. Studies have shown that phthalic acid is a well known allelopathic autotoxic substance, and it is also one of the substances with higher content in rubber tree root exudates. In order to explore whether phthalic acid has an autotoxic effect on rubber tree, the effects of different concentrations (0.05, 0.50, 1.00, 2.00 mmol/L) of phthalic acid solutions on the seed germination and seedling growth of rubber tree RRIM600 were investigated. Phthalic acid delayed the initial germination time of rubber tree seeds, and reduced the germination rate, germination speed and uniformity of seeds germination. Compared with the control, the germination rate, germination index, germination speed, and uniformity of seeds germination of 2.00 mmol/L phthalic acid trestment decreased by 23.60%, 42.75%, 37.18%, 58.69%. All concentrations of phthalic acid treatment inhibited the growth of shoot length, diameter of shoot base, root diameter, and reduced the seedling biomass accumulation. In the concentration range of 0.05-2.00 mmol/L, the shoot length, diameter of shoot base, root diameter, shoot weight and root weight reduced by 12.91% to 40.70%, 20.05% to 21.59%, 7.89% to 34.13%, 16.18% to 26.47%, 20.00% to 36.00%. The content of soluble sugar, proline and malondialdehyde (MDA) increased gradually with the increase of phthalic acid concentration, along with the degree of cell membrane lipid peroxidation gradually increased. The pigment content and catalase (CAT) activity of rubber tree seedlings increased first and then decreased with the increase of phthalic acid treatment concentration, while peroxidase (POD) and superoxide dismutase (SOD) activities decreased with the increase of phthalic acid treatment concentration. 0.05 mmol/L phthalic acid promoted the accumulation of chlorophyll b in seedlings, decreased the content of chlorophyll a, increased the activity of CAT, reduced POD and SOD activity. When the concentration reached 0.50 mmol, the content of chlorophyll a, total amount of chlorophyll, and carotenoid accumulated to the maximum, and decreased the activities of POD and SOD, at 2.00 mmol/L, the activities of POD and SOD continued to decrease. In conclusion, phthalic acid delayed the initial germination time of rubber tree RRIM600 seeds, decreased the seed germination rate and germination rate, led to the disorder of the physiological function of rubber tree seedlings, and inhibited the growth and development. The results could provide basic data support for the evaluation of the autotoxicity of phthalic acid on rubber trees.

Ardisia gigantifolia Stapf is native to Hekou county, Yunnan province, with few wild individuals, and is listed as a critically endangered species. It has important protection value and good prospect of garden development and application. The stem segments of aseptic seedlings of A. gigantifolia were used as the explants to establish a propagation in vitro. The results showed that the optimal medium for callus induction was WPM+0.50 mg/L TDZ+0.10 mg/L NAA, and the induction rate of callus was 96.67%. The optional medium for callus proliferation was WPM+0.50 mg/L TDZ and the multiplication coefficient was 4.42. The optimal medium for callus differentiation was WPM+2.00 mg/L 6-BA+0.20 mg/L NAA, and the induction rate reached 100%. The optional medium for adventitious bud proliferation culture was WPM+4.00 mg/L 6-BA, the multiplication coefficient was 3.90, and the cluster buds grew well. The optional rooting medium was WPM+10% coconut water+0.20 mg/L NAA, the rooting rate reached 100%, the root system developed well and the test-tube plantlets grew vigorously. Plantlets were transplanted into the mixture substrate with the volume ratio of perlite and peat soil of 1∶3, the survival rate was 96.67% after 60 days and plants grew well. This study can provide technical support for the large-scale seedling production of A. gigantifolia, as well as theoretical basis and technical support for the protection, seedling breeding, and molecular biology research of this species.

In order to explore the growth and branching genetic variation of Casuarina equisetifolia half-sib families at seedling stage, the annual seedlings of 40 half-sib C. equisetifolia families were used as the materials. Genetic analysis was carried out on seven traits: seedling height, ground diameter, dry weight, root shoot ratio, number of lateral branches, angle of lateral branch, and length of lateral branch. At the same time, cluster analysis and multi-trait comprehensive evaluation method were used to select excellent families. The results showed that the growth and branching traits of C. equisetifolia half-sib families at seedling stage varied widely, and the differences of the seven traits among families reached extremely significant level. The family heritability of the growth and branching traits ranged from 0.36 to 0.83, which were controlled by moderate or strong inheritance. Four excellent families, 3-265, 5-373, 1-266 and 2-343, were selected at a 10% selection rate. The real gains of seedling height, ground diameter, dry weight, number of lateral branches and length of lateral branches of the selected families was 21.14%, 19.10%, 41.83%, 19.97% and 18.88%, respectively. The genetic gains were 17.55%, 15.66%, 29.70%, 15.57% and 15.10%, respectively. The effect of selection work was remarkable. C. equisetifolia seedlings have great breeding potential among families. The excellent families selected in this study not only enrich the excellent germplasm resources of C. equisetifolia, but provide better germplasm materials for the subsequent genetic improvement and forest construction of C. equisetifolia.

A field experiment was conducted to investigate the effects of different fertilization and irrigation rates on plant growth, nutrient uptake, yield and fruit quality of MD-2 pineapple. The goal was to deal with the seasonal drought in the main producing areas of pineapple, and determine the appropriate rates of fertilization and irrigation for high-yield and high-quality pineapple variety growth, which can increase the yield and efficiency. MD-2 pineapple was subjected to a field plot experiment with eight treatments: (1) CK (no fertilization and no irrigation), (2) F₁W₀ (no irrigation with conventional fertilization), (3) F₁W₁ (fertigation with 50%-60% of field capacity), (4) F₂W₁ (25% reduction in fertilizer application with 50%-60% of field capacity), (5) F₃W₁ (50% reduction in fertilizer application with 50%-60% of field capacity), (6) F₁W₂ (fertigation with 30%-40% of field capacity), (7) F₂W₂ (the amount of fertilizer was reduced by 25%, 30%-40% of field capacity), and (8) F₃W₂ (the amount of fertilizer was reduced by 50%, 30%-40% of field capacity). The results showed that the total number of leaves, root, stem, leaf, stalk, fruit and plant dry biomass accumulations, and plant N, P, K accumulations of MD-2 pineapple of F₁W₁ treatment were significantly higher than those of CK. Compared with F₁W₀, F₁W₁ treatment significantly increased the plant height, stem height, stem diameter, D leaf length, D leaf width, peduncle diameter, and stem, leaf, peduncle, fruit and plant dry biomass accumulations, and N and K accumulations of plant. The transverse diameter, vertical diameter, fruit weight and fruit yield of MD-2 pineapple of F₁W₁ treatment were significantly higher than those of CK and F₁W₀. And the fruit yield of F₁W₁ was 117.46% higher than CK and 99.40% higher than F₁W₀, while there was no difference between F₁W₀ and CK. The fertilizer contribution rate and agricultural efficiency of each fertigation treatment were significantly higher than those of F₁W₀. The contents of vitamin C and titratable acid of F₁W₀ were the highest, but the sugar-acid ratio was the lowest. Under the same irrigation level, there were no significant differences in growth, dry biomass accumulation and fruit quality of MD-2 pineapple among different fertilization levels. The yield of F₁W₁ treatment was the highest, which had no significant difference with that of F₃W₁ treatment. The irrigation water productivity of F₃W₁ treatment was equivalent to that of all treatments with low irrigation level. Under the same fertilization level, the soluble sugar content and sugar-acid ratio of treatments with high irrigation rate were significantly higher than those of treatments with low irrigation rate. Considering the growth situation, yield and quality of MD-2 pineapple, irrigation water productivity and fertilizer contribution rate, F₃W₁ treatment was the optimal combination of fertilization and irrigation, which was beneficial to realize high yield, quality and efficiency of MD-2 pineapple.

A technique system for detecting the genome size of Camellia oleifera by flow cytometry was established to analyze the genome size genetic diversity between the superior lines of C. osmantha var. Yilu and C. vietnamensis var. Hongu 23, and to provide reference for selection of special germplasm and analysis of ploidy difference, based on the key links such as the type of dissociated liquid, the plant of internal reference, the tissue organ of the test material, evaluation indexes such as the nuclear dissociation, the degradation of secondary metabolites, the stability of the cell peak, the clear degree of the main peak, the separation degree of the main and miscellaneous peak, the easy degree of sampling, the difference of the genome size of the internal participating samples, the accuracy of genome size determination and the coefficient of variation. The method was used to determine the genome size of the superior lines of C. osmantha and C. vietnamensis. The disintegrating effect of WPB and mG^b was better among common dissociative fluids WPB, Tris-MgCl₂, OTTO, mG^b. Pean and corn were the favorable internal plants, and young leaf or root tip were the favorable experimental materials. The genome size of the superior lines of C. osmantha was from 5.12 to 9.31 Gb, with an average value of 7.60 Gb, the genome size distribution of the superior lines No. 1, No. 37 and No. 45 was extreme, and it was speculated that there were ploidy differences or interspecific hybridization between the parents. The genome size of superior lines of C. vietnamensis varied from 9.17 to 9.85 Gb, the mean value was 9.47 Gb. There was significant difference in genome size between the superior lines of C. osmantha and C. vietnamensis.

Chili pepper (Capsicum annuum) is an important vegetable and condiment, but the current cropping pattern makes its continuous cropping obstacles increasingly prominent. Most studies show that reasonable rotation is an effective method and means to solve the continuous cropping obstacles of chili pepper. Industrial hemp (Cannabis sativa) is an ideal rotation plant, but the effect of industrial hemp rotation on alleviating the continuous cropping obstacle of chili pepper is not clear. In order to explore the effect of industrial hemp-chili pepper rotation on the growth and physiology of chili pepper, this study took the industrial hemp variety Yunma 1 and two local chili pepper varieties Taiyanghong and Yangjiaola as the materials in the agronomic experiment greenhouse of Yunnan University from 2018 to 2019. Pot experiments were carried out on chili pepper continuous cropping and industrial hemp-chili pepper rotation, respectively. The morphological growth and physiological and biochemical indexes of chili pepper after industrial hemp rotation were comparatively analyzed, and the effect of industrial hemp rotation on the growth and physiology of chili pepper in the later season was preliminarily explored. The results showed that the main physiological and biochemical indexes of chili pepper in the rotation group and the continuous cropping group had the same trend. However, compared with the chili pepper continuous cropping, the chlorophyll content of the two chili pepper varieties increased to a certain extent at 40, 50, 60 and 100 days after seedling thinning, while the activities of antioxidant enzymes (SOD and POD) and root activity also increased correspondingly, especially in the harvest period (100 days after seedling thinning) in the industrial hemp-chili pepper rotation. After the industrial hemp rotation, the net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i) and transpiration rate (T_r) of the leaves of the two pepper varieties were significantly increased at 40, 50 and 60 days after seedling thinning, resulting in a significant increase in plant height, stem diameter, shoot dry weight and root shoot ratio at harvest stage. Compared with the chili pepper continuous cropping, the plant height of Yangjiaola and Taiyanghong increased by 20.65% and 16.85%, the stem diameter increased by 16.32% and 19.94%, the aboveground dry weight increased by 15.39% and 27.50%, and the root shoot ratio increased by 33.26% and 25.47% in the industrial hemp-chili pepper rotation, respectively. In conclusion, the industrial hemp rotation enhanced the physiological activity of late season chili pepper and better maintained the normal growth and development of chili pepper. The results have a guiding significance for the selection of reasonable planting mode of chili pepper in the future.

Paris polyphylla var. alba, a medicinal plant of Melanthiaceae, is classed as the national second-grade protected species of China. With the increasing demand for raw materials of Rhizoma paridis, the wild resources of P. polyphylla var. alba have been seriously damaged. In order to protect the genetic resources and clarify the systematic positon of this species, Illumina Hiseq X Ten platform was used to sequence the chloroplast (cp) genome. The structural characteristics of the complete cp genome sequence and phylogenetic relationship of P. polyphylla var. alba in Paris were analyzed. The results showed that the cp genome was 163 944 bp in length with a typical quadripartite structure with a large single-copy (LSC) region of 84 179 bp, a small single-copy (SSC) region of 12 967 bp, and a pair of 33 399 bp inverted repeats (IRs). The genome contained 134 genes, including 88 protein-coding genes (PCGs), 38 tRNA genes and 8 rRNA genes. A total of 645 long repeats and 97 simple sequence repeats (SSRs) loci were detected in the complete cp genome, in which forward and palindromic repeats were the mainly long repeat types, and most of SSRs had A/T base preference. Phylogenetic analysis based on the complete cp genomes showed that Paris formed a monophyletic group, and could be further divided into five major clades corresponding to five sections, respectively. The varieties of P. polyphylla are located in Sect. Euthyra, but are not clustered a monophyletic group, and P. polyphylla var. alba is closely related to P. mairei. This study would provide a scientific basis for studying the phylogeny, species identification and resource conservation of Paris.

In order to understand the flora characteristics of wild seed plants in Mashan county, Guangxi, the wild seed plant resources were investigated. The results showed that there were 1504 species of wild seed plants in Mashan county, Guangxi, belonging to 170 families and 740 genera. Angiosperms were dominant and gymnosperms were relatively scarce. From the perspective of family and genus composition, monospecific families and oligospecies were the main body, while the genera and species of seed plants were concentrated in medium and large families, small genera and monospecific genera. The plant distribution area was rich in types, with obvious tropical nature and certain temperate components, showing a transitional nature from tropical to subtropical. Compared with neighboring areas, Mashan county has richer plant diversity, and its flora is the closest to Binyang county, Guangxi. In general, Mashan county is rich in plant diversity, with prominent tropical components, rich in life and mainly herbaceous plants, with ancient and young flora coexisting, and the unique phenomenon is prominent, reflecting the characteristics of the flora of the Beibu Gulf as a whole.

Pitaya has both edible and medicinal value, the major fruit in tropical and subtropical regions of China. But it is susceptible to diseases during storage. Pitaya soft rot disease is a common major disease in storage. To clarify the pathogen of pitaya soft rot, the antagonist activity and inhibition effect of antagonistic actinomycetes against pathogen, pitaya with soft rot characteristics were used to isolate pathogens by tissue separation, purification and identification. The pathogenicity of pathogen was determined by inoculated without injuries and fruit acupuncture inoculation. 26 Streptomyces spp. as the antagonist strains were tested. The inhibitory effects of cell-free filtrate on mycelial growth of the pathogen were studied by agar block method and growth rate methods. Control effect of LWL1827 cell-free filtrate spraying of different concentration and PPO, POD and PAL activity of concentration 1∶10 were carried out. ZYW18 was the pathogenic fungus according to the pathogenicity test, which was identified as Fusarium verticillioides based on morphological characteristics and molecular identification. LWL1827 could significantly inhibit the mycelia growth of ZYW18, the radius of inhibition zone was (18.32±2.13)mm, and the colony extension was inhibited significantly, the inhibitary rates of sterile fermentation filtrates with different concentrations of 1∶5、1∶10、1∶50 was 91.23%±3.11%, 87.21%±3.22%, 80.22%±2.03%, respectively. LWL1827 cell-free filtrate (1∶10) significantly improved the activity of PPO, POD and PAL, even 2-3 times higher than that of the control. Meanwhile, LWL1827 could reduce disease index and improve its control effect. Conclusively, the pathogen that causes pitaya is identified as F. verticillioides. This is the first report of pitaya caused by F. verticillioides. The Streptomyces sp. LWL1827 has significant antagonistic effect, and the antagonistic strain LWL1827 has potential value in biological control against pitaya soft sot.

Five different light filter bags including red, green, blue, white and double kraft bag were selected to study the effects of different color filter bags on the sunburn incidence and fruit quality of pomegranate. The sunburn index of pomegranate fruit decreased from 62.42% to 100%, comparing to non-bagged fruits. Principal component analysis showed that bagging mainly affected four quality indicators of pomegranate fruit, including titratable acid, soluble solids content, soluble sugar and seed hardness. The content of soluble sugar increased by 26.72% in the red bag, the seed hardness decreased by 35.58%, and the SSC and titratable acidity did not change significantly. The content of titratable acid, SSC and soluble sugar in the green bag fruit increased by 5.80%, 7.03%, 15.40% respectively, seed hardness decreased by 56.30%. The content of titratable acid, SSC and soluble sugar in the blue bag increased by 11.59%, 9.38%, 23.55%, and the seed hardness decreased by 16.26%. Titratable acid, SSC of fruits and seed hardness in the white bag decreased by 17.39%, 2.89% and 35.63%, respectively. The titratable acid and soluble solids of the fruits in the kraft bag increased by 8.70% and 11.17%, respectively, and the seed hardness decreased by 38.91%. The comprehensive analysis of the sunburn incidence and the internal and external quality of the fruit found that the red bag significantly improved the appearance quality of the fruit, reduced the fruit sunburn index by 91.80%, significantly increased the soluble sugar content, and reduced the seed hardness. Therefore, the red bag is an ideal fruit bag for Hongyushizi.