长链非编码RNA POT1-AS1在宫颈癌顺铂耐药中的作用研究

背景同步放化疗是晚期宫颈癌(cervical cancer,CC)的治疗方法,顺铂(cisplatin,CDDP)是目前临床化疗使用的主要药物之一,CDDP耐药的发生严重制约了其临床应用,因此针对CDDP耐药发生机制的研究对CC的治疗至关重要。目的探索长链非编码RNA(long non-coding RNA,lncRNA)POT1-AS1在宫颈癌CDDP耐药中的作用。方法基于TCGA数据库,分析POT1-AS1在CC组织及正常组织中的表达情况,并分析POT1-AS1的表达量与预后的关系。采用CCK-8实验评估CDDP处理后的耐药细胞系和亲本细胞系、siPOT1-AS1组和siNC组的活力并测定相应的半抑制浓度(the half maximal inhibitory concentration,IC50)。实时荧光定量PCR(quantitative real-time PCR,qPCR)检测POT1-AS1在耐药细胞系及相应亲本细胞系中的表达以及POT1-AS1表达与CDDP作用时间的相关性。克隆形成实验检测POT1-AS1对CDDP耐药细胞增殖情况的影响。PI/DAPI双染荧光用于评估POT1-AS1与CDDP诱导的细胞死亡的相关性。结果POT1-AS1在CC肿瘤组织中高表达,并与不良预后相关。耐药细胞系的细胞活力及IC50值显著高于亲本细胞系(P<0.001),POT1-AS1沉默组的细胞活力及IC50值显著低于阴性对照(negative control,NC)组(P<0.001),差异均有统计学意义。POT1-AS1在耐药细胞系中的表达显著高于亲本细胞系(P<0.001),且随着CDDP给药时间的延长而增加。沉默POT1-AS1后可显著抑制耐药细胞的增殖能力(P<0.01)。与NC组相比,POT1-AS1沉默组的CC耐药细胞死亡率显著增加(P<0.01),尤其是在加入CDDP作用后(P<0.01)。结论POT1-AS1与宫颈癌CDDP耐药密切相关,并通过抑制CDDP诱导的细胞死亡发挥促癌作用。

基于改进POT模型的混凝土浇筑仓温度双控指标拟定

基于小概率法或最大熵法拟定浇筑仓温度双控指标时对样本数据的极端值保留程度欠缺,而现有文献关于温度双控指标拟定所选取的典型龄期没有明确的物理意义。为避免混凝土浇筑仓温度超过容许最高温度,结合某混凝土坝在高温季节浇筑仓实测温度,采用POT模型拟定了混凝土浇筑仓在绝热温升半熟龄期下的温度双控指标。为了提高结果可靠性,选用基于3σ准则改进的阈值确定方法,并提出了一种改进的POT模型条件概率确定方法。工程实例分析表明:采用改进POT模型与典型小概率法拟定的温度双控指标较为接近,但由于POT模型重点考虑了极端条件下的浇筑仓温度,对极端事件概率下的估计更为准确,由此求出的温度双控指标更合理。此外,选取混凝土浇筑仓在绝热温升半熟龄期作为拟定温度双控指标的典型龄期更利于工程推广。

Study on a Bowl-based Mechanism for Transplanting Potted Strawberry Seedlings

To improve the efficiency of fetching and transplanting seedlings for the mechanization of strawberry planting,an integrated transplanting mechanism was designed with protruding,fetching and planting performance to achieve rapid fetching and pushing bowl movements.According to the working principle of the slewing mechanism,a kinematics model and the optimization goal were established,respectively.Based on visual auxiliary analysis software,optimal parameters were obtained.A three-dimensional model was established to obtain a simulation trajectory by means of a virtual simulation design analysis.Three-dimensional printing technology was used to manufacture the test prototype,and the actual working trajectories of the test prototype were extracted using high-speed photography technology,which verified the consistency of the actual trajectory with the theoretical and simulated trajectories.A prototype transplanting experiment was performed with the success rate of seedling extraction of 91.2%and excellent planting rate of 82.8%,which met the requirements for integrated strawberry harvesting,planting and transplanting.The experimental results verified the correctness and feasibility of the design of integrated transplanting mechanism.

极值BMM模型与POT模型对面板堆石坝安全监控指标拟定的比较研究

研究极值理论中极值BMM模型和POT模型在大坝安全监控指标拟定上的运用,通过引用经济学上的分位数和极端风险(VaR)值的概念,根据对应公式计算出相应数值进行量化比较分析。研究结果表明,极值BMM模型和POT模型在高置信水平下均能反映出数据的极端风险状况;在99%置信水平下两模型VaR值均大于在95%置信水平下的VaR值;在99%置信水平下极值BMM模型计算出的VaR值比POT模型下的VaR值更大,且接近于拟定指标,表明极值BMM模型下VaR值更能反映出数据的极值状态;在指标拟定方面,极值BMM模型较为适合拟定数据范围内的警戒指标,而POT模型指标拟定结果是超越样本数据本身,具有一定的预测性,适合拟定为样本数据的预测指标。

Evaluation of Four Varieties of Sweetpotato (Ipomeoa Batatas (L.) Lam) under Different Sources of Planting Material for Field Performance and Viral Load

Sweetpotato is an important crop for food security in many developing countries which is cultivated using vine cuttings. Studies have revealed that there are at least fifteen well characterized viruses known to infect sweetpotato of which 10 are economically important that contribute to yield reduction. Planting materials use by farmers are often infected by one or more of these viruses. The aim of this study was to evaluate three different sources of planting materials of different health status for their field performance and virus presence. The sources of planting materials were in vitro generated platelets, symptomless Field materials and Farmer’s materials. Four sweetpotato varieties Apomuden, Bohye, Ligri and Dadanyuie were selected from each source of planting material. The trial was laid in a split plot design with the sources of planting material allocated to main plots and the varieties to sub-plots. The plantlets of the four varieties were planted at Botanga Irrigation Scheme in Northern region of Ghana. Viral symptom scores were taken twice, score 1 being the average from 4 - 7 weeks after planting (WAP) and score 2 being the average from 8 - 11 WAP. Nitrocellulose Membranes Enzyme Linked Immunosorbent Assay (NCM-ELISA) kits were employed for the detection of sweetpotato viruses on the field. The source of planting materials significantly influenced (P In vitro generated material showed the least symptoms of virus followed by Field materials. Apomuden and Bohye varieties recorded the highest virus score in the first and second virus symptom observational score respectively. NCM-ELISA revealed that the viruses SPFMV, SPMMV, SPMSV, SPCFV, SPCSV, and CMV were significantly present among the different sources of planting materials. In vitro, Field and Farmer materials recorded NCM-ELISA score of 0.225, 1.075 and 1.500 respectively. Apomuden variety recorded the highest virus score in the assay. Vine and root yield was higher among the in vitro generated material. Farmers should use laboratory cleaned material however, in the absence of such material they should select field material showing no symptom of virus.

Influence of Planting Date on the Incidence and Severity of Leaf Spot Disease in Telfairia occidentalis Hook f.

Telfairia occidentalis Hook f. is attacked by a destructive fungal pathogen Epicoccum sorghinum which causes leaf spot disease in the field. In Came-roon, this critically important seed and leaf vegetable is predominantly culti-vated under natural environmental conditions. An experiment was conducted in 2019 and 2020 during the long and short rainy seasons in Santchou to de-termine the influence of planting dates between seasons on the incidence and severity of leaf spot disease. The design used was a 2 by 4 factorial random-ized complete block design with three replications and four sowing dates. Data for disease incidence and severity documented fortnightly, were submitted to analysis of variance using SPSS version 23, and the means were separated by Duncan’s multiple range test (DMRT) at a 95% confidence interval. Statistical analysis revealed that the long rainy season registered a significantly (p p < 0.05) disease incidences and severities to other planting dates investi-gated. We established that the first three planting dates in the long rainy season could be a management practice to reduce disease prevalence.

The unimodal latitudinal pattern of K,Ca and Mg concentration and its potential drivers in forest foliage in eastern China

Potassium(K),calcium(Ca),and magnesium(Mg)are essential elements with important physiological functions in plants.Previous studies showed that leaf K,Ca,and Mg concentrations generally increase with increasing latitudes.However,recent meta-analyses suggested the possibility of a unimodal pattern in the concentrations of these elements along latitudinal gradients.The authenticity of this unimodal latitudinal pattern,however,requires validation through large-scale field experimental data,and exploration of the underlying mechanisms if the pattern is confirmed.Here,we collected leaves of common species of woody plants from 19 montane forests in the north-south transect of eastern China,including 322 species from 160 genera,67 families;and then determined leaf K,Ca,and Mg concentrations to explore their latitudinal patterns and driving mechanisms.Our results support unimodal latitudinal patterns for all three elements in woody plants across eastern China,with peak values at latitude 36.5±1.0°N.The shift of plant-functional-type compositions from evergreen broadleaves to deciduous broadleaves and to conifers along this latitudinal span was the key factor contributing to these patterns.Climatic factors,mainly temperature,and to a lesser extent solar radiation and precipitation,were the main environmental drivers.These factors,by altering the composition of plant communities and regulating plant physiological activities,influence the latitudinal patterns of plant nutrient concentrations.Our findings also suggest that high leaf K,Ca,and Mg concentrations may represent an adaptive strategy for plants to withstand water stress,which might be used to predict plant nutrient responses to climate changes at large scales,and broaden the understanding of biogeochemical cycling of K,Ca,and Mg.

Tomato detection method using domain adaptive learning for dense planting environments

This study aimed to address the challenge of accurately and reliably detecting tomatoes in dense planting environments,a critical prerequisite for the automation implementation of robotic harvesting.However,the heavy reliance on extensive manually annotated datasets for training deep learning models still poses significant limitations to their application in real-world agricultural production environments.To overcome these limitations,we employed domain adaptive learning approach combined with the YOLOv5 model to develop a novel tomato detection model called as TDA-YOLO(tomato detection domain adaptation).We designated the normal illumination scenes in dense planting environments as the source domain and utilized various other illumination scenes as the target domain.To construct bridge mechanism between source and target domains,neural preset for color style transfer is introduced to generate a pseudo-dataset,which served to deal with domain discrepancy.Furthermore,this study combines the semi-supervised learning method to enable the model to extract domain-invariant features more fully,and uses knowledge distillation to improve the model's ability to adapt to the target domain.Additionally,for purpose of promoting inference speed and low computational demand,the lightweight FasterNet network was integrated into the YOLOv5's C3 module,creating a modified C3_Faster module.The experimental results demonstrated that the proposed TDA-YOLO model significantly outperformed original YOLOv5s model,achieving a mAP(mean average precision)of 96.80%for tomato detection across diverse scenarios in dense planting environments,increasing by 7.19 percentage points;Compared with the latest YOLOv8 and YOLOv9,it is also 2.17 and 1.19 percentage points higher,respectively.The model's average detection time per image was an impressive 15 milliseconds,with a FLOPs(floating point operations per second)count of 13.8 G.After acceleration processing,the detection accuracy of the TDA-YOLO model on the Jetson Xavier NX development board is 90.95%,the mAP value is 91.35%,and the detection time of each image is 21 ms,which can still meet the requirements of real-time detection of tomatoes in dense planting environment.The experimental results show that the proposed TDA-YOLO model can accurately and quickly detect tomatoes in dense planting environment,and at the same time avoid the use of a large number of annotated data,which provides technical support for the development of automatic harvesting systems for tomatoes and other fruits.

Fungi Associated with Sand and Plants from Marine Coastlines: Potential Relevance for Human Health

The fungal community associated with beach sand and plants located along marine coasts are an under-studied area of research despite its potential relevance to human health. In this study, we isolated and identified the cultivable mycobiota associated with sand and plants collected along the coast of Gran Canaria (Spain) using culture-dependent and -independent methods. Clinically relevant species belonging to Cryptococcus spp. and related genera such as Naganishia and Papilotrema were isolated and identified from shoreline plants. Moreover, Candida tropicalis was isolated from beach sand, and Aspergillus fumigatus and Aspergillus terreus strains were associated with both types of samples (i.e., plants and beach sand). We conclude that beach sand and shoreline plants are potential reservoirs of fungi of high clinical interest. We recommend including beach sand and plants from the environment when assessing the quality of marine coastal systems. Our results open a framework for studying the natural marine environment and its role in the epidemiology of infectious diseases in order to more accurately manage public health.

A perspective review on the biosynthesis of plant-based secondary metabolites and their application as potent drugs

Many phytochemicals and their derived metabolites produced by plants are extensively employed in commercial goods,pharmaceutical products as well as in the environmental and medicalfields.However,these secondary metabolites obtained from plants are in low amounts,and it is difficult to synthesize them at the industrial level.Despite these challenges,they may be utilized for a variety of medicinal products that are either available in the market or are being researched and tested.Secondary metabolites are complex compounds that exhibit chirality.Further,under controlled conditions with elicitors,desired secondary metabolites may be produced from plant cell cultures.This review emphasizes the various aspects of secondary metabolites including their types,synthesis,and applications as medicinal products.The article aims to promote the use of plant secondary metabolites in the management and treatment of various diseases.

Sorghum Productivity and Its Farming Feasibility in Dryland Agriculture:Genotypic and Planting Distance Insights

Sorghum(Sorghum bicolor L.Moench)is an essential food crop for more than 750 million people in tropical and sub-tropical dry climates of Africa,India,and Latin America.The domestic sorghum market in Indonesia is still limited to the eastern region(East Nusa Tenggara,West Nusa Tenggara,Java,and South Sulawesi).Therefore,it is crucial to carry out sorghum research on drylands.This research aimed to investigate the effect of sorghum genotype and planting distance and their interaction toward growth and sorghum’s productivity in the Gunungkidul dryland,Yogyakarta,Indonesia.In addition,the farm business analysis,including the feasibility of sorghum farming,was also examined.The research used a randomized complete block design(RCBD),arranged in a 5×4 factorial with 3 replicates.The first treatment consisted of 5 varieties(2 high-yielding varieties(Bioguma 1 and Kawali)and 3 local sorghum varieties(Plonco,Ketan Merah,and Hitam Wareng)).The second treatment consisted of 4 levels of planting distance,namely 50×20 cm,60×20 cm,70×15 cm,and 70×20×20 cm.Analysis of variance was used to analyze the data,where Duncan’s multiple range test(DMRT)was used post hoc.Plant height,panicle height,panicle width,panicle weight,stover weight,grains weight/plot,and productivity were significantly affected by sorghum varieties(p<0.05).However,there was no significant effect from the planting distance treatment and no interaction between planting distance and varietal treatments.Ketan Merah had the highest height,panicle length,and panicle width,while Bioguma 1 had the highest stover weight,panicle weight,grain weight/plot,and productivity.There was a significant linear regression equation,i.e.,productivity=0.0054–0.0003 panicle height+0.4163 grains weight/plot.Our findings on farm business analysis suggested that four out of five tested sorghum varieties were feasible to grow,except for the Ketan Merah variety.The most economically profitable sorghum variety to grow in Gunungkidul dryland was Bioguma 1.

Physiological and Biochemical Responses of Perennial Ryegrass Mixed Planting with Legumes under Heavy Metal Pollution

In artificially controlled pot experiments,perennial ryegrass was mixed with other leguminous plants(white clo-ver and alfalfa)and treated with lead,zinc and cadmium(337 mg·kg^(-1),648 mg·kg^(-1),and 9 mg·kg^(-1),respectively)to simulate compound pollution conditions.The results showed that the concentrations of heavy metals,trans-port factors,and bioconcentration factors in mixed planting of ryegrass decreased compared with those in mono-culture.Regardless of whether heavy metal pollution was introduced,mixed planting increased the aboveground and underground biomasses of ryegrass.The different mixed planting treatments had no significant impact on the chlorophyll concentration of ryegrass.The mowing time,mixed planting treatment,and heavy metal treatment had impacts on antioxidant and osmotic adjustment substances,and there were some interactions.The mixed planting treatment did not significantly affect glutathione concentration,cysteine concentration,or nonprotein thiol.Mixed planting generally increased the nitrogen and phosphorus concentrations of ryegrass while reducing the stoichiometric ratio of carbon,nitrogen,and phosphorus.These results suggest that the mixed planting of ryegrass with legumes promotes the growth of ryegrass in the presence of high concentrations of heavy metal pollution.However,it does not enhance the ability of ryegrass to remediate heavy metal pollution in the soil.

Characterization of blueberry exosome-like nanoparticles and miRNAs with potential cross-kingdom human gene targets

Edible plant derived exosome-like nanoparticles(ELNs)have been shown to have multiple nutraceutical functions.However,the diversity of plant materials makes the plant derived ELN study challenging.More efforts are still needed to explore the feasible isolation methods of edible plant derived ELNs and the possible roles of food-derived ELNs in improving human health.In this study,a size exclusion chromatography based method was compared with the traditional ultracentrifugation method to isolate blueberry derived ELNs(B-ELNs),and the miRNA profile of B-ELNs was analyzed by high-throughput sequencing.A total of 36 miRNAs were found to be enriched in B-ELNs compared with berry tissue,and their potential cross-kingdom human gene targets were further predicted.Results showed that size exclusion chromatography was effective for B-ELN isolation.The most abundant miRNAs in B-ELNs mainly belonged to the miR166 family and miR396 family.Target gene prediction indicated that B-ELNs could potentially regulate pathways related to the human digestive system,immune system and infectious diseases.

Potential role and therapeutic implications of glutathione peroxidase 4 in the treatment of Alzheimer's disease

Alzheimer's disease is an age-related neurodegenerative disorder with a complex and incompletely understood pathogenesis. Despite extensive research, a cure for Alzheimer's disease has not yet been found. Oxidative stress mediates excessive oxidative responses, and its involvement in Alzheimer's disease pathogenesis as a primary or secondary pathological event is widely accepted. As a member of the selenium-containing antioxidant enzyme family, glutathione peroxidase 4 reduces esterified phospholipid hydroperoxides to maintain cellular redox homeostasis. With the discovery of ferroptosis, the central role of glutathione peroxidase 4 in anti-lipid peroxidation in several diseases, including Alzheimer's disease, has received widespread attention. Increasing evidence suggests that glutathione peroxidase 4 expression is inhibited in the Alzheimer's disease brain, resulting in oxidative stress, inflammation, ferroptosis, and apoptosis, which are closely associated with pathological damage in Alzheimer's disease. Several therapeutic approaches, such as small molecule drugs, natural plant products, and non-pharmacological treatments, ameliorate pathological damage and cognitive function in Alzheimer's disease by promoting glutathione peroxidase 4 expression and enhancing glutathione peroxidase 4 activity. Therefore, glutathione peroxidase 4 upregulation may be a promising strategy for the treatment of Alzheimer's disease. This review provides an overview of the gene structure, biological functions, and regulatory mechanisms of glutathione peroxidase 4, a discussion on the important role of glutathione peroxidase 4 in pathological events closely related to Alzheimer's disease, and a summary of the advances in small-molecule drugs, natural plant products, and non-pharmacological therapies targeting glutathione peroxidase 4 for the treatment of Alzheimer's disease. Most prior studies on this subject used animal models, and relevant clinical studies are lacking. Future clinical trials are required to validate the therapeutic effects of strategies targeting glutathione peroxidase 4 in the treatment of Alzheimer's disease.

Dry Breeding and Dry Planting Techniques for Indica Hybrid Rice in Karst Mountain Areas of Gejiu City

Based on the arable land situation in Gejiu City,upland dry planting of indica hybrid rice is being expanded in Karst mountain areas with a rainfall of over 1400 mm and an altitude of 1100-1600 m to develop grain production.This paper gives a specific description of hybrid rice upland dry seedling technology,upland transplanting technology,fertilization technology,field management,weed prevention and control technology,and disease and pest control.

Potential efficacy and mechanism of medicinal plants on chronic kidney disease-associated vascular calcification:a review

Vascular calcification is a crucial risk factor that affects the incidence and mortality of cardiovascular disease in chronic kidney disease patients.Modern medicine relies on calcium-phosphorus binding agents,calcium mimetics,active vitamin D,and hemodialysis to prevent and treat vascular calcification,however,their efficacy is unsatisfactory and adverse reactions often occur.Medical plant therapy can act as an integrative regulator in patients with chronic kidney disease-associated vascular calcification,which can significantly improve patients’symptoms,but its specific mechanism has not been fully elucidated yet.In this paper,we reviewed the domestic and international theoretical studies on the pathogenesis mechanism of chronic kidney disease-associated vascular calcification in recent years,summarized eight active ingredients of medicinal plants as well as four compound formulas for improving chronic kidney disease-associated vascular calcification,and explored the mechanism of action of herbal medicine,which will provide a new strategy for promoting the prevention and treatment of vascular calcification.

Effects of Planting Density on Yield and Sourcesink Characteristics of Sweet Potato[Ipomoea batatas(L.) Lam]

[Objective] The aim was to resolve the issue of sparsely planting （37 500-40 500 plants/hm2） of sweet potato in hilly areas. [Method] The starch-oriented Jishu No.21 and raw-eating oriented Jishu No.22 were studied to explore effects of planting density on yield and sink and source characteristics of sweet potato. [IRe- suit] Leaf area index of Jishu No.21 and Jishu No.22 were increasing upon planting density. Leaf area index of the same planting density showed a single-peak curve. Specifically, leaf area index grew fast during the 40th-80th d after planting, and reached the peak on the 80th d after planting, followed by decreasing. What＇s more, ventilation and sunshine transmission both declined upon planting density, as well as the number of leaf, the number of branch, the length of vine, dry and fresh weights of stem and leaf. When planting density exceeded 75 000 plants/hm2, the yield of sweet potato dropped dramatically. Besides, the optimal planting density tended to be volatile upon cultivars. For example, the range of 45 000-60 000 plants/hm2 is the optimal planting density of Jishu No.21 and the range of 60 000-75 000 plants/hm2 is the optimal planting density of Jishu No.22. [Conclusion] It can be concluded that rational planting densities would well coordinate sweet potato growth of ground parts and underground parts to get a high yield by providing a rational group structure. Considering the optimal planting density differs upon cultivars, it is necessary to take genotype, environment, soil fertility and planting density into consideration in determining planting density.

Construction of Efficient Multiple Planting Patterns of Potato for Tridimensional Climate in Subtropical Region of China

[Objective] The aim was to make full use of light-heat resources to expand the potato planting area on the base of ensuring the production of main grain crops and the limited arable land. [Methods] Through catch crops, multiple cropping and intercropping, new multiple planting patterns of potato with efficiency are constructed, for the purpose of increasing yield and benefit of potato. [Result] In irrigated plain and hill area, three new planting patterns such as autumn potato/rope-rice,winter potato-rice-autumn potato, and autumn（winter） potato-rice were constructed.In dry land of plain and hill area, three new planting patterns such as spring（winter）potato/maize/sweet potato, spring（winter） potato/maize-autumn potato, and wheat ＋ winter potato/maize/sweet potato were constructed. In plateau mountainous area, spring potato/maize was constructed. [Conclusion] With use of new planting patterns, the cropping index of new patterns was 200%-300%, while the accumulated temperature utilization was 68.9%-93.4%, light energy utilization was 0.98%-1.59% and straw utilization was 50%-100%. To compared with traditional planting patterns, the yield increased by 2.6%-93%, and benefit increased by 15.8%-284.3%. Furthermore,multiple planting patterns of potato have become main planting patterns in increasing yield and income in Sichuan.

Research on Potted-Tray Grown Rice Seedling Transplanting by Machine

[Objective] In order to cultivate seedlings that are adaptable to farming system and transplanter, the technology for transplanting potted-tray grown rice seedlings with machine was introduced and studied. [Method] The transplanter-spe-cific seedlings were cultivated with potted-tray, bowl-shaped blanket tray and soft plastic flat plate respectively. The seeding rate and 20-50-day-old seedling height were investigated for the 3 sowing patterns. After the transplanting, the missing transplanting rate, upright seedling rate, seedling injury rate and green-returning pe-riod were investigated. [Result] Nursing seedlings with potted-tray had the advan-tages of saving seeds, high sowing precision, high seedling rate and high seedling rate. The 20-40-day-old seedlings had relatively high leaf age, seedling height and root number. However, 40 d after the transplanting, the growth of seedlings was slowed. The quality difference was smal est among the 20-day-old seedlings that were nursed with 3 different patterns, but since then the quality advantage of pot-ted-tray grown seedlings had been more and more prominent. There was smal dif-ference in quality among the 30-day-old seedlings. However, for the seedlings that were older than 40 d, the transplanting quality of potted-tray grown seedlings was higher than that of bowl-shaped blanket tray grown seedlings and soft plastic flat plate grown seedlings. In addition, the green-returning period of the potted-tray grown seedlings was significantly shortened. [Conclusion] Compared to the bowl-shaped blanket tray grown seedlings and soft plastic flat plate grown seedlings, the potted-tray grown seedlings were more suitable to transplant by machine in the wheat-rice double cropping areas of Chengdu Plain.

Suitable Date of Seeding, Planting Density and Water Use Efficiency for Propagation of Stock Seed Potato in Mountainous Region of Southwest Sichuan

[Objective] The experiment was conducted to study suitable date of seed- ing and density of spring potato at the stock breeding base in Ebian County at an elevation of 1 200 to 1 500 m. [Methods] Virus-free Potato ＂Chuanyu 13＂ was used as material to study the effects of date of seeding and density on growing period, germination rate, yield and water use efficiency of spring potato in the field. [Result] With the postponement of date of seeding, the days from sowing to germination shortened, while the germination rate, the number of tubers per plant, the number of middle and small tubers in a group, yield and water use efficiency all increased. Planting density had no effects on the days from sowing to germination and the ger- mination rate, while the number of tubers per ptant, the number of middle and small tubers in a group, yield and water use efficiency increased significantly along with the increasing planting density. [Conclusion] At an elevation of 1 200 m to 1 250 m in Ebian County, the suitable date of seeding for potato was from February 9 to March 1, and the suitable planting density was 12×10^4 plants per hm^2, however, in the optimum planting density has not been found so that it needs further research,