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.

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.

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.

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.

Mango is known as the "king of tropical fruits" for its unique flavor and rich nutrition. However, mango is extremely perishable during postharvest ripening, and the decay loss caused by anthracnose is the most serious. Therefore, how to prevent and control mango anthracnose after harvest has become a bottleneck problem restricting the healthy development of mango industry. In this paper, Tainong No.1 mango was used as the experimental material, and the green cinnamon essential oil composite chitosan lotion was used as the treatment means to study its control effect and mechanism on postharvest mango anthracnose, which would provide theoretical basis and practical reference for the development of postharvest mango storage, transportation and preservation industry in China. The results showed that the treatment of 0.5% cinnamon essential oil+0.3% chitosan had the best control effect on mango anthracnose, the treatment of 0.03% cinnamon essential oil could completely inhibit the growth and spore production of mango anthracnose in vitro, and the treatment of 0.01% and 0.02% cinnamon essential oil had obvious destructive effect on mango anthracnose mycelium. The complex treatment significantly inhibited the expansion of mango anthracnose disease spot, increased the content of disease resistance related substances lignin, total phenol (TP) and hydrogen peroxide (H₂O₂), and increased the content of disease resistance related enzymes phenylalanine ammonia lyase (PAL), peroxidase (POD),β-1,3 glucanase (β-1,3-GA) and chitinase (CHI). It can be seen that cinnamon essential oil composite chitosan lotion has a good control effect on mango anthracnose by inhibiting or destroying the growth and spore production of mango anthracnose mycelium, and inducing mango fruit to improve disease resistance. Therefore, the proper concentration of cinnamon essential oil combined with chitosan lotion treatment would provide a new green way to control mango anthracnose after harvest.

Exploring the characteristics of dry-wet climate change and its impacts on crop yield can provide scientific basis for agricultural production planning and meteorological disaster prevention under climate change. Based on the daily ground observation data of meteorological stations in Zhanjiang area from 1960 to 2020 and the statistical data of rice, sugarcane and peanut yields from 1990 to 2020, the aridity index calculated by reference crop evapotranspiration (ET₀) and precipitation were used as drought index to analyze the characteristics of dry-wet climate change, and the impact of dry-wet climate change on crop yield was analyzed. The results showed that the interannual variation of precipitation in Zhanjiang area fluctuated greatly, and the annual average precipitation was 1534.41 mm, showing an insignificant rising trend. The temperature rised significantly at the rate of 0.18 ℃/10 a, and the annual average ET₀ and aridity index was 1242.72 mm/a and 0.87 respectively, showing an insignificant upward trend. According to the annual variation of the dryness index, from January to April and from October to December were the drought prone periods in Zhanjiang. The yield of rice, sugarcane and peanut showed a significant growth trend in the past 31 years, the increase of aridity index in April would reduce the yield of the three crops. The increase of aridity index in May would significantly increase the yield of peanut, but had no significant impact on the yield of the other two crops. The increase of temperature and the decrease of precipitation in June were conducive to the significant increase of rice and peanut yield. Sugarcane yield was not significantly affected by the change of temperature and precipitation, while the increase of dryness index in December significantly increased sugarcane yield. The results are of great significance for Zhanjiang and its surrounding areas agriculture to cope with climate change and improve the crop potential productivity.

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.

Banana (Musa spp.) is one of the most popular fruits in the world and is widely loved for its sweet taste and nutritious value, it is usually eaten after ripened. Bananas are rich in more than 90% resistant starch before they are unripe, and the effective use of resistant starch in green bananas can significantly increase the added value of the banana planting industry. In addition, green bananas are prone to producing a large number of defective fruits during the harvesting process, resulting in a serious waste of starch resources. In order to study the effect of autoclaving treatment on the digestion and structure properties of flour, three different banana cultivars: Dajiao, Fenjiao, and Gongjiao were chosen. By using scanning electron microscopy, dynamic light scattering, rapid paste viscometer, differential scanning calorimetry, Fourier transform near infrared spectroscopy, and X-ray diffraction analysis. To investigate the relationship between the structural changes and digestion properties of the three green banana flours before and after an autoclaving treatment was applied to them. The content of resistant starch in green banana flour decreased from 91.50%-93.33%(RS2 type) to 39.17%-44.63% (RS3 type) after autoclaving treatment. The scanning electron microscope results showed that powder granules were completely pasted and disintegrated, with variable particle size distribution and irregular shape. The amylose starch content increased from 23.3%-28.3% to 32.7%-37.0%, so that the thermal stability and gel enthalpy of green banana flour were significantly decreased (P<0.05) while the peak viscosity and breakdown was increased. The relative crystallinity of the green banana flour decreased from 28.98%-32.56% to 20.66%-22.26% after the autoclaving treatment. Despite this, the B-type crystalline structure was still preserved after the treatment. The new chemical bonds or functional groups were not found after the autoclaving treatment compared with green banana flour, and the short-range order R_1047/1022 was decreased from 1.031-1.166 to 1.016-1.122. The findings revealed that although the content of the resistant starch was reduced after autoclaving treatment, the type of resistant starch was changed from RS2 to RS3. This suggests that the stability of the resistant starch is greatly enhanced after autoclaving treatment. This research could offer a theoretical foundation for the production of heat-stable banana resistant starch, support the development of naturally starch-based materials, and is crucial for resolving the disparity between banana industry production and sales.

Cellulose is one of the main components of plant roots, and plays a key role in lodging resistance. CesA7 is for cellulose synthesis, but its function is unknown in sugarcane. Rice OsCesA7 gene was used as the reference sequence to conduct homology analysis and functional prediction in the genomes of Sacchrum spontaneum, S. hybrid and S. officinarum. Phylogenetic analysis showed that CesA7 in S. hybrid was closer to that in S. officinarum, and grasses were clustered together, but herbs and woody plants could not be separated clearly. The promoter region of the sugarcane CesA7 genes had abundant light-responsive elements and methyl jasmonate element, indicating that the gene may be involved in the photomorphogenesis and the stress resistance response in sugarcane. Interaction prediction of the protein and analysis of the promoter indicated that CesA7 had interaction with MYB transcription factor, suggesting that CesA7 played a role in crop growth and development and stress response. In addition, functional predictions of CesA proteins in rice and sorghum showed involvement in regulating cellulose synthesis and lignin degradation processes. Transcriptomic analysis of roots and leaves of seven representative species of sugarcane at seedling stage revealed that CesA7 expression level in roots was much higher than that in leaves, suggesting that CesA7 might regulate sugarcane root development. The SNP variation of the gene was detected in the germplasm of sugarcane, and the nucleotide diversity was the highest in S. spontaneum. The nucleotide diversity in the exon region was significantly higher than that in the intron region, and the highest diversity was found in the region of exon 4 (about 2000 bp) of the gene. It is speculated that the functional differentiation of different alleles are caused by the balancing selection of this locus. After multiple sequence alignment combined with resequencing data analysis, two potential molecular markers were identified, which could distinguish S. spontaneum and S. officinarum samples. The study would provide theoretical guidance for subsequent research and use of CesA7 gene to improve sugarcane variety.

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.