Dendrobium sinense is a tropical plant endemic to Hainan Island with great ornamental and medicinal values. However, unascertained reference genes restrict the quantitative analysis of gene expression in the species. In this study, using our previous transcriptome data of D. sinense, the 164 candidate genes were identified with low variance (CV≤0.2) and moderate expressions (TPM between 10-300). By GO clustering, 24 candidate genes were selected from different functional groups to avoid the effect of co-expression on further stability analysis. In order to avoid the false positive of genomic DNA that may remain in the template during RT-qPCR amplification, primers across introns were designed in this study, and amplification primers that met the requirements of 15 candidate reference genes were screened by electrophoresis. To ensure the specificity of RT-qPCR amplification, LightCycler 96 was used for melting curve analysis. According to the RT-qPCR data of 15 candidate genes, four tools were used to evaluate the expression stability. The results of multiple algorithm analysis showed that CLP1 & SEC23, SEC23 & CPY71, CLP1 & SEC23 and RNG1L & PECT were the best reference genes under drought stress. After comprehensive sorting, SEC23 and CLP1 were selected as the most stable reference genes under drought stress. In different tissues of D.sinense, ADF11 & IBR5, PRP19 & CLP1, ADF11 & CLP1, ACBP2 & IBR5 were identified as the best reference genes, respectively. After comprehensive analysis, ADF11 and ACBP2 were identified as the most stable reference genes in different tissues. Combined with the above drought stress and different tissue analysis data, IBR5 and CPY71 were finally determined as stable reference genes under comprehensive conditions. The validation of internal reference genes showed that compared with the traditional Actin internal reference, the internal reference genes screened in this study could obtain more accurate RT-qPCR calibration results, indicating that the generated internal reference genes had extremely high stability. In summary, this study provides ideas for identifying stable reference genes using transcriptome data. For the first time, stable reference genes were identified in the whole genome of D.sinense, which laid a foundation for further study of gene expression and function.

Starch branching enzyme (SBE) play a key role in amylopectin biosynthesis and directly influence the content and structure of starch. Taro is a major tuber crop, widely cultivated in tropical and subtropical regions of the world. At present, there are few studies on SBE in taro, and the number, molecular structural characteristics and expression patterns of SBE genes in taro are not clear. In this study, a comprehensive analysis of taro SBE genes was conducted for the first time, and three SBE genes (CeSBE1, CeSBE2 and CeSBE3) were identified. The amino acid numbers of CeSBE1, CeSBE2 and CeSBE3 proteins was 828, 845 and 598, respectively, with molecular mass of 92 956.71 Da, 95 625.13 Da and 69 169.16 Da, and isoelectric point of 5.22, 5.41 and 7.36, respectively. Phylogenetic analysis showed that the three CeSBE proteins were divided into three different subgroups. Gene structure analysis showed that the number of CeSBE1, CeSBE2 and CeSBE3 exons was 16, 22 and 10, respectively. Conservative structural domain analysis showed that both CeSBE1 and CeSBE2 proteins had α-amylase_C and α-amylase structural domains and 7 motifs, while CeSBE3 protein had α-amylase and CBM_48 structural domains and 3 motifs. Analysis of cis-acting elements in the promoter region of CeSBE gene showed that a total of 55 cis-acting elements were predicted, 29 of which were functionally annotated, involving elements related to light response, hormone response, plant growth and development, and environmental stress. The three CeSBE genes were expressed in all tissues, with CeSBE2 being significantly expressed in corms and leaves (P<0.05). At different developmental stages of the corm, CeSBE2 had high expression at all developmental stages, showing a trend of increasing and then decreasing expression, with peak expression at 120 d of corm development. The increase in total starch and amylopectin content at different developmental stages of the corm was consistent with the trend of CeSBE2 expression, suggesting that CeSBE2 may be a key gene for amylopectin biosynthesis in taro. The study would enhance the understanding of CeSBE gene family members and provide the basis for genetic improvement of yield, quality and nutritional traits in taro.

Breadfruit is considered as the most potential food crop to solve tropical famine with high economic value. Breadfruit was introduced from several countries, and there are no research on the systematic taxonomic and genetic diversity analysis about it. The objective of this study was to specify the genetic distance and relationship among breadfruit and its closest wild relatives. For genetic diversity analysis, 33 pairs of SSR primers with clear amplified bands, high polymorphism and good stability were selected from 75 pairs of SSR primers. PCR amplification was performed, and the products were detected by 8% denaturing polyacrylamide gel. Genetic diversity correlation analysis was performed by NTSYS software. The results showed that the polymorphism ratio of amplified bands of the 33 SSR markers was 94.57%. 199 number of polymorphic sites were detected, with an average of 6.030 per marker. The PIC values of the SSR markers ranged from 0.623 to 0.940, with an average of 0.865. The genetic similarity coefficients among the breadfruit resources ranged from 0.517 to 0.951, with an average genetic similarity coefficient of 0.685. Furthermore, germplasm ZZP possessed the greatest variation among individuals, with an average genetic similarity coefficient of 0.626. Germplasm XYS1-3 possessed the least variation among individuals, with an average genetic similarity coefficient of 0.723. At the genetic similarity coefficient of 0.713, the 30 breadfruit resources were clustered into five groups, with XBL and breadnut type I (ZZP, LX, STH, HJ5) which used for landscaping clustered into one group, breadfruit SLLK, XYS2, XYS3, XYS5, XYS6 and YN clustered into one group, breadnut type Ⅱ SLM2, YDNXY1, G1 and G2 clustered into one group, breadnut type Ⅱ W1, W3, SMY, 8-4, 8-3, 5-5 and 5-6 clustered into one group. The three-dimensional diagram could better distinguish XBL and breadnut type I ZZP, LX, STH, HJ5 from the breadfruit and breadnut type Ⅱ resource with edible value. Based on the cluster analysis, we speculated that XYS2, XYS3, XYS5 and XYS6 might be introduced from Vietnam, XYS1-3, YBG and XYS1 might be introduced from Indonesia. Furthermore, FJ was regarded as a breadfruit germplasm. The present study reported the genetic diversity of breadfruit resources in China firstly, and elucidated the genetic relationship among breadfruit resources. In addition, the results could provide theoretical basis for variety breeding and identification of breadfruit complex.

The study of the leaf anatomical structure of macadamia germplasm resources and its drought resistance was aimed to provide theoretical basis for macadamia seed breeding, introduction and cultivation. 11 leaf anatomical parameters of 20 macadamia germplasm resources were analyzed and compared using paraffin section technique. The drought resistance of different germplasm resources was comprehensively evaluated by the principal component analysis, membership function method and systematic clustering method. The results showed that macadamia leaves were typical leaves with different faces, and there were significant differences among the anatomical structure indexes of different germplasm resources (P<0.01). Principal component analysis showed that the order of the eleven indexes reflecting the drought resistance of macadamia was thickness of palisade parenchyma thickness>leaf thickness>cell tense ratio>palisade/spongy tissue>sponge ratio>upper cuticle thickness>lower epidermis thickness>upper epidermis thickness>lower cuticle thickness>midrib thickness>spongy parenchyma thickness. According to the membership function method and the weight of each index, the order of drought resistance of the 20 macadamia germplasm resources was as follows: No. 1>No. 19>No. 5>No. 10>No. 14>No. 11>No. 16>No. 7>No. 2>No. 20>No. 8>No. 13>No. 18>No. 15>No. 9>No. 3>No. 6>No. 4>No. 17>No. 12. After "Z-score" standardization, the 20 germplasm resources were classified into 3 groups at 15 genetic distances. No. 1, No. 5, No. 10, No. 11, No. 14, No. 16 and No. 19 had thicker leaves, developed palisade tissue, higher palisade/spongy tissue and cell tense ratio than other germplasms, and had higher water retention and photosynthetic capacity, so they were high drought-resistant groups. The leaves, epidermis and cuticle of No. 3, No. 4, No. 6, No. 9, No. 12, No. 15 and No. 17 were thin, and the leaves were relatively loose, showing low drought resistance, so they were low drought resistance groups. The drought resistance of other germplasms was in the middle.

Based on specimen diagnostics and literature studies, six new records of Angiosperm in Guizhou Province were reported, namely Lepidium didymum L. (Brassicaceae), Lactuca serriola L. (Asteraceae), Dactylicapnos lichiangensis (Fedde) Hand.-Mazz. (Papaveraceae), Dinetus duclouxii (Gagnep. & Courch.) Staples (Convolvulaceae), Zingiber atrorubens Gagnep. (Zingiberaceae), Carex phyllocephala T. Koyama (Cyperaceae). Main morphological identification characteristics, distribution descriptions, voucher specimens and photographs were provided for all species, and the systematic position changes of some species were also discussed. The voucher specimens were deposited in the Herbarium of the Natural Museum of Guizhou University (GACP).

Leaf anatomy, plant growth traits and leaf ecological stoichiometry were analyzed in 8 pineapple cultivars (Gold diamond, Red skin, Red fragrant, Hand torn, Gold, Bali, Watermelon, and Mango) in a common garden in Jiangmen, Guangdong, China. The purpose was to explore the differentiation of functional traits between different pineapple cultivars, and the relationships between leaf ecological stoichiometry and plant growth as well as the plant nutrient limitation. The results showed that leaf stomatal density was the highest in the middle of leaves in most pineapple cultivars, and leaf thickness increased from the upper position to the lower position. There were significant differences in stomatal density, guard cell length, leaf thickness and anatomical proportion in different leaf positions within the same cultivar or in the same leaf position between different pineapple cultivars. Different pineapple cultivars differed in the leaf C, N, P and K content. Pineapple plants required large amount of K, as leaf K content was much higher than N and P content. Leaf N and P content in pineapples were lower than those in grassland plants in China. The leaf content of N and P of pineapple was higher than that of the plants in grasslands and in farmland ecosystems in China, while the leaf content of C, C∶N and C∶P were higher than those of the plants in grasslands and in farmland ecosystems in China, indicating that pineapple plant is reducing the dependence on nutrients through special leaf morphological or histological structure, agreement with the "Demand reduction strategy". Moreover, leaf C content, C∶P and N∶P were significantly negatively correlated with total leaf biomass, which was consistent with the growth rate hypothesis. Ranging from 6.40 to 19.07 across all pineapple cultivars, leaf N∶P values indicated that plant growth of Golden and Mango pineapples were limited by P; Golden diamond, Red skin, Hand torn and Watermelon pineapples were restricted by N, while Red fragrant and Bali pineapples were co-limited by N and P. This study twould provides a theoretical foundation for the cultivar selection and the agricultural management of pineapples.

To study the physiological characteristics of high light efficiency in cassava cultivar Ku50, W14, a wild type, wild relatives of A4047 and cultivated species of Ku50 were used as the materials to investigate the character of photosynthetic physiology during different varieties of cassava by measuring the photosynthetic pigment content on functional leaves, net photosynthetic rate (including the photosynthetic rate curve under different light intensity and photosynthetic daily variation) and chlorophyll fluorescence parameters (including mainly the actual photosynthetic efficiency of PSⅡ-Y(Ⅱ), and non-photochemical quenching-NPQ). The result showed that the content of various photosynthetic pigments in Ku50 was significantly higher than that in W14, but no significant difference with that in A4047, suggesting that Ku50 and A4047 may have higher photosynthetic carbon fixation capacity. The net photosynthetic rate of Ku50 was slightly higher than that of A4047 and much higher than that of W14 on the photosynthetic daily variation and Ku50 and A4047 had no obvious midday photoinhibition phenomenon while W14 had, suggesting that Ku50 and A4047 may have higher light conversion efficiency and stronger resistance to high light. The photosynthetic rate curve under different light intensity showed that three varieties of cassava all did not arrive the light saturation point up to the maximum light intensity of 2500 μmol/(m²·s), and the net photosynthetic rate also showed Ku50>A4047>W14. Among them, Ku50 was about 40 μmol/(m²·s), A4047 was about 34 μmol/(m²·s), but W14 was only about 15 μmol/(m²·s). This result was consistent with photosynthetic daily variation and also suggested that Ku50 had stronger resistance to high light and higher light energy conversion efficiency. In addition, the chlorophyll fluorescence parameters were measured to analyze the absorption, distribution and utilization of light energy in different varieties cassava. The result showed that under high light the Y(II) of Ku50 was significantly higher than that of W14, but slightly higher than that of A4047 which had no significant difference (P>0.05). And the NPQ of Ku50 was significantly lower than those of W14 and A4047, indicating that the light energy dissipated into heat on Ku50 was lower than those of W14 and A4047, which in turn proved that the light energy conversion efficiency of Ku50 was higher than those of W14 and A4047, and which was consistent with the results of photosynthetic pigments content and net photosynthetic rate. In conclusion, this research proved that high light efficiency in cassava cultivar Ku50 was induced by high light, and had higher tolerance and utilization rate to high light than wild type of W14 and wild relatives of A4047.

Trichoderma spp. is an important biocontrol microorganism in the fungal disease prevention and control of green agriculture. Which is widely developed as Trichoderma agent for biological control, biofertilizer and soil amendment. The development of traditional Trichoderma fungicide is limited to the screening of Trichoderma strains and the optimization of fermentation conditions. Therefore, it is necessary to explore a new application mode of Trichoderma. Due to intolerance to storage and high costs of transportation and development, coconut water is often directly discarded as waste in the production of coconut industry. In this study, coconut water was compounded with Trichoderma spores and medium elements as water-soluble fertilizers to explore the effects on seed germination and seedling physiological indexes of cucumber. The results showed that adding medium element to coconut water and adjusting pH to 7 had the best effect on the production of Trichoderma spore, and the sporulation reached 2.32×10⁷ CFU/mL. The treatment group A of water-soluble fertilizer compounded with medium element in Trichoderma spp. and coconut water and treatment group B of water-soluble fertilizer compounded with Trichoderma spp. and coconut water significantly promoted the germination of cucumber seeds, and the germination rates of cucumber seeds was 94.44%and 87.50%, respectively, compared with sterile water (CK), which increased by 28.30% and 18.87%, respectively. Pot experiment showed that the plant height and root length of treatment group A was 24.01 cm and 27.76 cm, respectively, which was 48.03% and 47.27% higher than those of CK, which significantly promoted the growth of cucumber seedlings. At the same time, the fresh weight and dry weight of stem and root of cucumber seedlings in treatment group A were also significantly higher than those of CK. Further, we determined the content of total chlorophyll, reducing sugar and soluble protein, the activity of peroxidase (POD) and catalase (CAT) of cucumber seedlings in treatment group A, compared with CK, which increased by 97.46%, 66.32%, 58.85%, 32.67%, and 40.31%, respectively; and the content of malondialdehyde (MDA) was significantly decreased, which was 79.96% lower than that of CK. In summary, the treatment group of water-soluble fertilizer compounded with medium element in Trichoderma spp. and coconut water could significantly promote cucumber seed germination and seedling growth, improve the contents of total chlorophyll, reducing sugar, soluble protein, POD and CAT activity, decrease MDA content of seedlings, and enhance the ability of cucumber to resist stress.

The harvested Newhall navel orange fruits are easy to quality deterioration and spoilage, which seriously affecting the commodity value and shelf-life. Kadozan, a novel commercial liquid chitosan formulation, can be conveniently used for fresh produce postharvest treatment by diluting Kadozan to the required concentration with water. The influences of Kadozan with dilution of 1∶800 (V_Kadozan∶V_{Kadozan+water}) on the storage quality and storability of Newhall navel orange fruit were investigated. Postharvest Newhall navel oranges were immersed with distilled water (the control) and chitosan for 5 min, respectively, and then stored at (18±1)℃ and 80% relative humidity. During the storage, the samples were taken every 30 days to determine the rate of commercially acceptable fruit, the percentage of weight loss, respiration rate, fruit appearance color characteristics, the contents of chlorophyll and carotenoid in pericarp, and the contents of pulp nutrients. Compared with the control fruits, during storage, chitosan (Kadozan) treatment could reduce fruit weight loss, fruit respiration rate, retain higher rate of commercial acceptable fruit, higher contents of pericarp chlorophyll and carotenoid, higher values of pericarp L^*, b^* and h°, but lower values of pericarp a^* and citrus color index (CCI). In addition, Kadozan treatment could maintain higher contents of soluble solids (TSS), titratable acid (TA), soluble total sugar, sucrose, vitamin C, carotenoids, flavonoids and total phenol in the pulp of Newhall navel orange during storage. When stored for 120 d, the rate of commercially acceptable fruit and the percentage of weight loss in Kadozan-treated oranges was 95.56% and 4.39%, respectively. From the above data, it is concluded that the treatment of chitosan (Kadozan) can improve the storability and maintain the better quality of postharvest Newhall navel orange fruit, indicating the dilution of 1:800 (V_Kadozan∶ V_{Kadozan+Water}) could be a safe and facile approach to maintain the quality and extend the shelf life of Newhall navel orange after harvest.

Potato is the fourth largest food crop in the world, but little research has been done on this crop about rice husk mulching and copper (Cu). Rice husk is a by-product of rice processing and has great potential to reduce environmental pollution. Plastic film mulching gives us a non-negligible problem of environmental pollution, and even crop yields will be affected. Compared with black film, it has the advantages of wide source, lower cost and no need for recycling, which can basically be used locally. Previous studies have shown that the photosynthetic pigment content, photosynthetic rate, nutrient content, plant height, stem thickness, tuber number, above ground dry weight and yield of potato plants were enhanced by both Cu solution dip treatment and foliar spray of Cu. In this experiment, the accumulation and distribution of Cu in potato plants under different mulching patterns were investigated by using potato "Favorita" as the material and three mulching patterns: bare ground (CK), rice husk (6 000 kg/hm²) mulching (DK) and black film mulching (HM) for winter cultivation in the field. The results showed that the accumulation of Cu in stems and leaves showed a trend of increasing and then decreasing under different mulching patterns, while the accumulation in tubers and whole plants showed a trend of gradually increasing. The accumulation of Cu in stems and leaves ranged from 13.45%~17.70% and 82.30%~86.55% of the whole plant 10 d after full seedling emergence to 2.99%~3.53% and 8.40%~10.56% 58 d after full seedling emergence, respectively. The accumulation of tubers increased from 26.76%~29.60% 22 d after full seedling emergence to 85.91%~88.68% 58 d after full seedling emergence. The Cu accumulation of plants under DK treatment was generally higher than that of LD and HM treatments in the whole growth period. The Cu accumulation of plants under DK treatment was 38.01%, 80.92%, 40.24%, 72.45% more than that of CK treatment in stem, leaf, tuber and whole plant respectively, and 92.21%, 47.22%, 48.12%, 45.16% higher than than that of the HM treatment, respectively. The accumulation of Cu in potato plants 10 d after full seedling emergence was positively correlated with the accumulation of Cu at the later stage, and the accumulation of Cu in stems and leaves was also positively correlated with the yield until 58 d after full seedling emergence. The difference in accumulation by site is due to the fact that in the early growth period, when potato plant is still in the seedling stage, stems and leaves are the sites of Cu accumulation. As the plant grows, tubers are gradually formed. About 31 days after full seedling emergence, the growth of stems and leaves gradually slow down, while the tubers are in the growth phase. At this time, the accumulation center shifts to the tuber, from stems and leaves, which shows that the accumulation of stem and leaves gradually decreases, while the accumulation of tuber continues to increase. The reasons for the higher accumulation of DK than CK and HM may be as follows. First, rice husk, on the other hand, can not only act as a thermal insulation layer to isolate strong external heat, but also improve soil water storage efficiency, increase soil water content, and have significant effects in reducing soil temperature. Second, rice husk can increase soil organic carbon content after being degraded as exogenous organic matter, and the study found that the soil available Cu content was significantly and positively correlated with soil organic carbon content. The experiment showed that under the test conditions, the accumulation of Cu by potato plants could be effectively increased under rice husk mulching at 6000 kg/hm² level.