Cassava is an important food crop in tropical regions, and one of the main breeding goals is to cultivate new lines with high β-carotene, low cyanogenic glucoside and waxy taste. In order to screen promising edible lines from breeding materials, the study developed a MATE-SNAP marker based on a mutation of G→A in the coding region of cyanogenic glucoside transporter gene MATE which resulted to amino acid change and affected its transmembrane structure stability. Combining with the β-carotene PSY2-SNAP and waxy quality GBSSⅠ-SNAP markers, 12 parent lines, carrying 1-2 target alleles, were selected from 50 cassava germplasms, and totally hybridized 10 cross-combinations according to flowering period among different years. Firstly, 134 erect or middle branched candidate lines were screen out through seedling, transplanting and preliminary field trial. Secondly, 13 edible promising lines which aggregated 2-3 target alleles, were chosen by using MATE/PSY2/GBSSⅠ-SNAP markers together. The content of of cyanogenic glucoside in root flesh was determined by spectrophotometry, the value of SC9 was 49.24 μg/g, and those of 13 promising lines were in the range of 38.82-76.51 μg/g; the content of β-carotene in root flesh was determined by acetone colorimetry, the value of SC9 was 184.75 μg/hg, and those of the six yellow-root lines were within the limits of 101.58-154.10 μg/hg; the content of amylopectin in root flesh was determined by dual wavelength spectrophotometry, the values of P13-1 and V7-14, whose alleles were GG that genotyped by GBSSⅠ-SNAP marker, was 82.46% and 83.79%, respectively. Based on this, 5 lines, A5-138, A2-213, P7-6, V4-8 and V4-19, were found to be the potential new edible cassava varieties by taste grading. In conclusion, marker-assisted selection can quickly and accurately screen out the target lines from breeding materials and improve the efficiency of cassava genetic improvement.

To study the differences in the physical and chemical properties of biochar obtained from three legumes at different temperatures, and to determine the appropriate temperature range for legume biochar. Using leguminous plant peanut straw, soybean straw and stylofoam as raw materials, peanut straw biochar (Pe), soybean straw biochar (Be) and stylofoam biochar (St) were prepared at 300 ℃, 500 ℃ and 700 ℃. A Fourier infrared spectrometer was used to qualitatively analyze the functional groups on the surface of the biochar, and the surface morphology of the biochar was observed with a scanning electron microscope, and the physical and chemical properties, such as pH, C and N content, were measured. The results showed that the carbon content of biochar prepared from three kinds of raw materials increased with the increase of pyrolysis temperature at 300 ℃ to 500 ℃, and was basically stable after 500 ℃; the nitrogen content and yield of biochar decreased with the increase of temperature. Among the biomass charcoal prepared from the three materials, Be has the highest carbon content and C/N, and N content and yield are the lowest. The ash content, ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis temperature and different materials are all expressed as Be>St>Pe. Both the pore size and specific surface area of biochar increase with increasing temperature. The three raw materials of biochar form more stable aromatic compounds with increasing temperature, and the structure is mainly C=O and C=C. In this study, the suitable pyrolysis temperature of legume biochar is 500 ℃, and the temperature rises again, which has little effect on the physical and chemical properties of biochar. In summary, the soybean biochar produced by cracking at 500 ℃ is more used in farmland soil improvement, and can also try soil remediation, carbon sequestration and emission reduction applications.

Anoectochilus roburghii is a rare and endangered medicinal orchid with high economic value. High temperature is the primary limiting factor for its extensive production and cultivation. Breeding heat-resistant varieties is one of the most economical and effective measures to resist heat damage caused by high temperature. In this study, we analyzed the genetic diversity of 24 A. roburghii germplasm resources by Start codon targeted polymorphism (SCoT) molecular markers, and evaluated the heat tolerance of 20 samples by multivariate statistical analysis. The results of genetic diversity analysis showed that at the genetic coefficient was 0.602, A. roburghii germplasm could be divided into two groups: I and II, Group I was divided into two subgroups A and B, Anoectochilus formosanus was classifiedd into Group II alone. In subgroup A, except W from Yunnan, all the other resources were collected in the north and west of Fujian. Subgroup B mainly came from Southern Fujian and Guangxi. The cluster diagram showed that the relatives of A. roburghii from the same origin was close, and the presence or absence of reticulated veins was not the basis for the classification. Five physiological parameters were measured in the 20 samples. It was found that the chlorophyll content and SOD activity decreased obviously after heat treatment, and the relative conductance increased obviously, while the malondialdehyde and soluble protein contents of each resource were different after heat treatment. The preliminary evaluation of heat resistance was conducted by the multivariate statistical analysis method, and the results showed that four resources (TL, L1, A20, GZ1) were heat resistant, while five resources (TJ, HX, L, M, A21) were not.

In order to understand the diversity of phenotypic traits in F₁ segregation populations of date palm, this study used 143 F₁ segregation populations of date palms as test materials to analyze the diversity, correlation, principal component and cluster analysis of 17 phenotypic traits, including plant height, crown breadth, stem girth, number of branches and leaf spot incidence. The results showed that there was a high degree of phenotypic variation and rich diversity in F₁ segregation population of date palms. The variation degree of quantitative characters was high, the coefficient of variation ranged from 10.927% to 43.350%, and the coefficient of variation of stem girth was the largest. The coefficients of variation of quality traits ranged from 31.447% to 44.619%, among which the coefficients of variation of tiller leaf color and leaf hardness were 44.619% and 42.571%, respectively. The correlation analysis showed that plant height, crown breadth, stem girth, number of branches, the third branch of long, the thorn area length, the total number of tiller leaves, tiller leaves length, tiller leaves width, tiller leaf thickness and leaf color were positively correlated with each other. The incidence of leaf spot was negatively correlated with the other 16 traits. The principal component analysis showed that the cumulative contribution rate of the six principal components reached 87.51%, of which the characteristic value of the first principal component was 10.0836, and the contribution rate was 59.32%. It is mainly affected by the five indicators of plant height, third branch length, crown breadth, stem girth and branch number. The characteristic value of plant height is the largest, which is 0.2948, which mainly reflects the height and growth trend of date palm. The cluster analysis showed that the 143 F₁ generation dates could be divided into five groups: Group Ⅰ included 33 dates with the smallest crown, the least number of branches, the shortest tiller leaves length, and the highest incidence of leaf spot disease. Group Ⅱ included 39 dates resources with the shortest plant height, the smallest stem girth, the shortest third branch length, and the heaviest incidence of leaf spot disease. Group Ⅲ included 23 dates resources with longer tiller leaves, darker tiller leaves, erect plant type and mild incidence of leaf spot disease. Group Ⅳ included 33 dates resources with excellent phenotypic traits such as large ratio of leaf length to width of tiller leaves, stiffer tiller leaves and the least incidence of leaf spot disease. Group Ⅴ included 14 dates resources with small ratio of tiller leaves length to width ratio and open plant type. The results of this study can provide a theoretical basis for the breeding of superior parental traits in later stage of date palm.

Using compact varieties SC205, GR4 and umbrella varieties SC12, SC15 as the experimental materials, five treatments of 9, 36, 63, 90 leaves remained and no leaves removed were designed to study the differences of chlorophyll fluorescence and fresh tuber root yield to clarify the differences of chlorophyll fluorescence of functional leaves in different growth stages and leaves remained treatments and the effects of leaves number on fresh tuber root yield. The results showed that with the increase of leaves, the fresh tuber root yield increased, and the tuber root number, the fresh weight of stems and leaves and the harvest index increased first and then decreased. The average of tuber root yield per plant of 9, 36, 63, 90 and no leaf removed treatments was 0.94 kg, 2.22 kg, 2.65 kg, 2.91 kg and 3.35 kg, respectively. The maximum fluorescence yield (F_m) and maximum quantum yield (F_v/F_m) of compact varieties were higher than those of umbrella varieties. F_m and F_v/F_m of compact varieties was 0.885 and 0.739, respectively, and those of umbrella varieties was 0.838 and 0.707, respectively. The minimum fluorescence yield (F₀) of compact type was smaller than that of umbrella type, and that for the two plant type varieties was 0.219 and 0.231, respectively. F₀, F_m, F_v/F_m, ETR and Y(Ⅱ) decreased with the progress of leaf removed. With the increase of PAR, ETR increased gradually, and Y(Ⅱ) decreased sharply first and then slowly. The variation trend of chlorophyll fluorescence of cassava varieties with different plant types was the same, but the variation rule of different leaves was different. The ETR and Y(Ⅱ) of cassava functional leaves increased slightly when the number of leaves remained was small.

Edible cassava is an important food crop in the world and a characteristic potato crop in South China. New edible varieties with high β-carotene and excellent comprehensive quality are one of the important directions of cassava breeding. Manihot esculenta Crantz cv. Gui 9 was obtained from immature fruits, using embryo rescue technology, which were harvested from in-bred crossing population using XX048 as the female. The main characters of the variety were erect plant type, tubers distributed horizontally, cylindrical conical in shape, tubers of light brown skin, pink endothelium and orange flesh. The fresh tuber yield was (45.12±7.04) t/hm² and (40.84±3.88)t/hm² respectively in the regional test and production test. The starch content of fresh tuber detected was 26.3%, β-carotene content was 454 μg/100 g, hydrocyanic acid content was 10-20 mg/kg, tatal sugar content was 2.0 g/100 g, dietary fiber and potassium content was 4.43 g/100 g and 553 mg/100 g respectively. Gui 9 is an edible cassava variety in China with the highest β-carotene content in tuber at present, rich in β-carotene, dietary fiber and minerals, fresh taste crisp and sweet, known as "carrot cassava", with unique advantages in color and taste in cooking and making cassava juice. Gui 9 has high yield and strong adaptability with moderately resistance to cinnabar Tetranychus mites, and is suitable for dense planting and mechanical harvesting. It could be popularized in cassava producing areas such as Guangxi, Guangdong, Hainan and Jiangxi provinces. The breeding of Gui 9 would provide variety support for the development of cassava food, and promote the quality improvement, efficiency increase and sustainable development of cassava industry.

Cassava is the sixth-important grain crop in the world and the major cash crop in Southern China. Now cassava related industries play an important role in the local agricultural economy. Various kinds of diseases often happen and cause serious economic losses in the field, which become an important issue. This paper briefly reviewed the progress of cassava disease research, including the slow development stage from the founding of the P. R China to the 1980s, the fast development stage from the 1990s to the 2010s, and the rapid development stage after the 2010s. The latest research progress is the core part of this paper. Currently, there are four categories and eleven kinds of diseases that harm cassava in China. Cassava bacterial blight (CBB) is the most serious disease, and brown leaf spot occures in the largest area. Cassava mosaic disease (CMD) is the worst disease in the world, which has invaded mainland China. Chinese Academy of Tropical Agricultural Sciences and other institutions have launched the research of disease database construction and intelligent monitoring technology. The researcher had estimated the risk of five kinds of dangerous disease to cassava planting industry of China. For CMD and cassava brown streak disease, the research on the resistance evaluation of the main varieties, damage mechanism of virus, and detection methods were studied. As far as CBB, monitoring technology, genome sequencing of pathogen, pathogenic and copper resistant mechanisms, genetic variation of pathogen populations, selection of resistant germplasm and its function mechanism were investigated. The effective bactericide for CBB was screened, the efficient spraying and biological control technology were formed, along with the stem disinfection method was popularized in the field. In term of CMD, the occurrence area, virus identification, key factors for long range diffusion were confirmed in China, and significant advance was achieved in virus damage and propagation mechanism. The advance of monitoring and control technology on another seven kinds of common diseases was also expounded in this paper. With the development of the national economy, there have been new trends in China's cassava planting industry, such as food consumption and scaling planting. The authors further look forward to the number of participating institutions, the speed of scientific research progress, the boosting role of multidisciplinary integration, and new research hotspots will emerge in the future. This article would help relevant practitioners to better understand the current situation and research progress of cassava diseases in China, and also provide a reference for the research and application of monitoring technologies of other crop diseases in tropical areas.

Protein phosphatase 2C (PP2C) plays a key role in the ABA signaling pathway. In order to investigate the response process of the PP2C gene to abiotic stress in cassava, MePP2CAb gene was cloned from Arg7 in cassava using the RT-PCR technique. Bioinformatic analysis, autoactivation activity analysis, promoter activity analysis, and expression pattern analysis of the MePP2CAb gene under different stress and hormone treatments were conducted. The results showed that (1) the total length of the MePP2CAb gene was 1296 bp, encoding 431 amino acid residues. The MePP2CAb protein had a relative molecular weight of 47.08 kDa and a theoretical isoelectric point of 5.5. It exhibited structural domain characteristics of the PP2C family. Protein sequence analysis showed that MePP2CAb was most similar to PP2C sequences of Hevea rubber and Jatropha jatropha, with consistencies of 82.75% and 74.01%, respectively, and a conserved C-terminal. These results indicated that MePP2CAb belongs to the PP2C family. (2) The expression of the MePP2CAb gene was found to be higher in cassava storage roots, stems, and leaves, with the highest expression observed in storage roots. (3) MePP2CAb demonstrated self-activation activity, and its full-length promoter exhibited high activity. (4) The MePP2CAb gene belongs to the core ABA pathway, and promoter sequence analysis showed that it contained ABRE (abscisic acid responsiveness) elements, MeJA response elements, and a drought-induced motif. Under different stress and hormone treatments, low temperature and SA treatment significantly repressed the MePP2CAb gene, while mannitol, NaCl, ABA, and MeJA significantly induced its expression. In addition, the interaction between MePP2CAb and MePYL1 was also observed. These results suggest that MePP2CAb may be responsive to abiotic stress in cassava, although its role as a positive or negative regulatory factor remains unclear. These results provide a clue for further investigation into the role of the MePP2CAb gene in the ABA signaling pathway and the improvement of cassava's adaptation to abiotic stress.

Rubber tree (Hevea brasiliensis) is the only renewable resource among the four major industrial raw materials. The rubber tree anthracnose which infected by the Colletotrichum sp. is one of the most serious foliar disease of rubber production in China. In this study, we investigated the main rubber tree varieties (strains) and monitoring the occurrence and prevalence of anthracnose in Hainan province. It was found that PR107 and RRIM600 had the largest planting area, accounting for 51.06% (102 000 hm²) and 43.39% (86 700 hm²) respectively. The anthracnose of mature rubber plantations and value-added nurseries in Yangjiang Farm was occurred all year round, with the peak period from March to April; Therefore, the rubber tree planted in Hainan province was large, and the variety (strain) was single, so it was easy to break out and spread when the anthracnose was suitable. HCkHNQZ1736 isolated from the leaves of the rubber nursery of Yangjiang Farm in Qiongzhong County, was identified as a new strain of Colletotrichum karstii, which had highly pathogenic to four main varieties of rubber tree, PR107, RRIM600, Reyan 7-33-97 and Dafeng 95. Studied on the results of carbendazim and prochloraz-manganese sensitivity test of HCkHNQZ1736 and MeCkYN1705 showed that the two strains had no resistance to prochloraz-manganese, while the EC₅₀ was 0.0784 μg/mL and 0.0775 μg/mL respectively. However, HCkHNQZ1736 showed high resistance to carbendazim, at this time, the EC₅₀ was 1107.2654 μg/mL, while MeCkYN1705 had only 0.0554 μg/mL.

Cassava (Manihot esculenta Crantz) is the sixth-largest food crop in the world, nearly 700 million people in the world tropical regions take it as the primary food source, and it is also an important raw material for the production of starch, modified starch, fuel ethanol and other chemical products and feed in China. It plays an important role in eradicating hunger, poverty alleviation and rural revitalization in tropical areas. Cassava root is rich in starch, which can provide energy for livestock and poultry growth. Cassava stems and leaves are rich in protein, cellulose and vitamins and other nutrients, thereby becoming a high-quality protein feed resource. Energy value of cassava is similar to that of corn, thus boasting great development potential as the feed. In recent years, it has achieved good results in the breeding of livestock and poultry such as pigs, sheep and chickens. Therefore, it is of great significance of using cassava as energy feed and replacing corn and other raw materials to mitigating competition for food between human beings and livestock and improve the economic benefits of breeding. This article comprehensively analyzed the nutritional value of cassava and the research progress of its feed application, and put forward specific suggestions for further research and utilization to provide reference for the development of cassava feed industry in the future.