This article is the first to conduct prevention and control experiments on rubber tree powdery mildew and anthracnose using a heavy-load plant protection UAV (FBH300T), analyzing the effects of flight heights of 3 m, 5 m, 7 m, and application amount of 60 L/hm², 90 L/hm², 105 L/hm² on the distribution of droplet deposition on the upper and lower leaves of rubber trees. This study found that flight altitude and application amount has a very significant impact on droplet density and droplet coverage. It has been selected that the optimal application parameters for this aircraft model are a flight height of 5 m above the canopy, an application amount of 90 L/hm², and a flight speed of 5 m, this study utilized a new specialized agent 19% Baoyeqing ME, which can simultaneously treat various leaf diseases of rubber trees, as well as efficient agents such as 60% sulfur powder SC, 45% pentazolamide EW, and 50% sulfur triadimefon SC, which were used in conjunction with heavy-load plant protection UAV (FBH300T) to analyze the control effects of each agent on the powdery mildew and anthracnose of rubber trees. The results showed that among the four single agents, the 50% sulfur triadimefon SC had the best control effect on powdery mildew, followed by the 19%Baoyeqing ME; The best control effect on Anthracnose is 19% Baoyeqing ME, followed by 45% pentazole imidamide EW. Under the mixed application of chemical agents, the best control effect against powdery mildew and anthracnose was achieved by mixing 19% Baoyeqing ME and 60% sulfur powder SC at a ratio of 1∶1, followed by mixture of 19% Baoyeqing ME and 50% sulfur triadimefon SC at a ratio of 1∶1. The experimental results can provide a good reference basis for the maturation of UAV flight defense technology and the selection of special flight prevention agents for rubber tree leaf disease.

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.

The problem of soil salinization in my country is becoming more and more serious. Rice is the preferred food crop for the improvement of salinized land, but salt stress is one of the main abiotic stresses that influence the growth and yield of rice. In order to fully understand the effect of salt stress on the rice, 31 varieties (lines) of tropical rice with different salt tolerance were used as experimental materials, and experiments were carried out by hydroponics in seedling stage incubator and potted soil cultivation method in the whole growth period, to study the effects of 0 NaCl (CK), 0.3% NaCl and 0.6% NaCl on the growth, physiological and biochemical characteristics, and yield composition of tropical rice. The result showed that: (1) The seedlings and roots growth of tropical rice were inhibited under salt stress. The seedling height and root number were significantly decreased with the increase of NaCl concentration, the root length in 0.3% NaCl and 0.6% NaCl treatments was significantly lower than CK treatments; and the fresh weight of seedling in 0.6% NaCl treatments was significantly lower than CK and 0.3% NaCl treatments. (2) Chlorophyll accumulation of tropical rice leaves were decreased under salt stress. The contents of chlorophyll a, chlorophyll b and Car in the treatments with 0.3% NaCl and 0.6% NaCl concentrations were significantly lower than CK treatments. The accumulation of proline (Pro), malondialdehyde (MDA) and Na⁺ were increased. The content of Pro and MDA and Na⁺ in the treatments with 0.6% NaCl concentration were significantly higher than treatments with CK and 0.3% NaCl concentration. The accumulation of K⁺were decreased. The K⁺ content in the 0.3% NaCl and 0.6% NaCl concentration treatments was significantly lower than the CK concentration treatments. (3) Under salt stress, the tiller number, panicle number, panicle length, panicle grain number, thousand-kernel weight and yield of per plant were significantly decreased with the increase of NaCl concentration.

GATA transcription factors play an important role in regulating plant response to abiotic stress. In this study, an IbGATA16 gene was cloned from sweet potato and analyzed by bioinformatics. The expression pattern of IbGATA16 gene in sweet potato under drought and salt stress was analyzed. Experimental results show that the full length of IbGATA16 CDS sequence is 420 bp, and it encodes 139 amino acids. The molecular weight of IbGATA16 was 15.39 kDa, isoelectric point was 9.97. The full length of the genome is 582 bp, including 3 exons and 2 introns. IbGATA16 is an unstable hydrophilic lipid-soluble protein., and its subcellular localization predicts that the protein is located in the nucleus. It has the C-X₂-C-X₁₇-C-X₂-C domain and belongs to the typical GATA class of transcription factors. There are many cis-acting elements in the 1382 bp upstream promoter sequence of IbGATA16 gene, such as MYB, ABRE, and GARE-motif. The results of multiple sequence alignment and phylogenetic tree analysis showed that IbGATA16 protein was closely related to ItGATA16. The sequence of the N-terminal zinc finger domain is highly consistent, suggesting a possible similar function. The results of real-time fluorescence quantification showed that IbGATA16 was expressed in root, stem and leaf tissues of sweet potato, and the expression level of IbGATA16 in leaves was significantly higher than that in stem and root tissues. IbGATA16 was significantly induced by drought and salt stress, and after 0, 1, 3, 6, 12 and 24 h of drought and salt stress, the expression of IbGATA16 was significantly higher than that of 0 h. Under drought stress, the expression of IbGATA16 reached its peak at 1 h, and under salt stress, the expression of IbGATA16 reached the maximum at 3 h. IbGATA16 positively responds to drought and salt stress in sweet potato. These results indicated that IbGATA16 gene was involved in the response of sweet potato to drought and salt stress, and the regulation of IbGATA16 gene was different in roots, stems and leaves. This study provides a reference for further research on the biological function of IbGATA16 and its mechanism in response to stress in sweet potato.

Watercore is a kind of physiological disease of pineapple fruit, which causes the intercellular space of pineapple pulp tissue to be filled with cell fluid and appear as water-soaked, which seriously affects the edible value and commercial value of the fruit. Watercore has troubled the development of pineapple industry for many years, but its mechanism is not clear. In order to explore the pathogenesis of watercore in pineapple, this study took the main pineapple cultivar Comte de paris as the material, the paraffin section method was used to observe the process of watercore in pineapple fruit and the different tissue parts of normal and watercore fruit (flower stock, carpel, fruit sequence axis). The results showed that the cell structure of pineapple pulp was closely related to watercore: the cell structure of normal fruit pulp was complete, the cell space was obvious, the vascular bundle was intact, the phloem cells were arranged tightly and neatly, and the xylem ducts were arranged regularly. However, fruit flesh cells in watercore are squeezed and deformed, and the cell wall rupture results in incomplete cell structure, destruction of vascular bundle morphology, extrusion and deformation of phloem, and destruction of xylem ducts to form a cavity. With the deepening of the onset process of watercore, the xylem cavity becomes larger. Through the morphological observation of different tissue parts of normal fruits and fruit with watercore, it was found that the changes of cell structure caused by watercore in different tissue parts were basically the same. There were obvious differences in vascular bundle morphology and structure in different tissue parts. The vascular bundles in the fruit sequence axis and receptacle were in accordance with the typical characteristics of vascular bundles in monocotyledons. The vascular bundles were surrounded by a sheath composed of thick-walled mechanical tissue at the periphery of each vascular bundle. On the other hand, there were more sachmatous cells at both ends of the vascular bundle. The inner part of the vascular bundle sheath contains primary phloem and primary xylem without the middle bundle cambium. The vascular bundle structure of the carpel was atypical, and most of the vascular bundles were not surrounded by vascular sheath. Vascular tissues in the fruit sequence axis were the most developed, followed by receptacle, and vascular tissues in the carpel were the least developed. These results revealed the morphological changes of pineapple watercore during its occurrence and provided reference for further research on the mechanism of watercore.

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.

The study of crop spatial pattern has important theoretical and practical significance, and has become the frontier and hotspot of geography and ecology. This paper systematically summarized the current progress of allocation method, driving force analysis and simulation of crop spatial pattern. And in this paper, a mind map of research work is presented based on the discussion of the deficiencies and the trends in the study of crop spatial pattern. It is showed that the methods of statistical investigation, remote sensing and spatial model have their advantages and disadvantages in the work of crop spatial information allocation. And it is difficult to fully understand the process of crop spatial pattern change only from the perspective of natural driving force or socio-economic driving force in the work of driving force analysis and simulation of crop spatial pattern. It is suggested that the spatial information comprehensive allocation technology based on spatial model, the multi-factor and multi-scale driving force analysis method combining natural and socio-economic factors, and the simulation model coupling geographical model and socio-economic model will be the important development directions in the field of crop spatial pattern research.

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.

MNP (multiple nucleotide polymorphism, MNP) is a new molecular marker technology emerged with the development of molecular marker technology. While genotyping by target sequencing (GBTS) amplifies only one SNP site in one amplicon, MNP can amplify multiple SNP sites simultaneously in one amplicon based on GBTS. This technology has the features of low cost, high detection efficiency, flexible application and wide adaptability, Compared with SNP, MNP has better ability to differentiate varieties. In order to establish a rapid, accurate and efficient method for cassava variety identification and to screen MNP molecular markers suitable for cassava variety identification, this study screened highly polymorphic regions and designed primers in the whole genome range, and finally obtained 623 cassava MNP marker loci in the whole genome range, the cassava MNP markers were evaluated using 28 cassava varieties. The results showed that the MNP marker typing reproducibility was up to 100%. 4.07±1.68 alleles were detected in 28 cassava varieties, with a maximum of 12 alleles. When all cassava varieties were compared one by a one, 99.47%(376/378) of the differences between pairs were greater than 46%, with the proportion ranging from 0.3% to 81.0%, with a mean value of 71.78%. Meanwhile, MNP markers can be used for identification in the breeding process. In conclusion, the cassava MNP molecular markers developed in this study have high reproducibility, polymorphism and variety differentiation ability, and could be widely used for research on germplasm diversity, new variety breeding and variety identification of cassava.

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.