Transport of cadmium from soil to grain in cereal crops: A review

Due to rapid urbanization and industrialization, many soils for crop production are contaminated by cadmium(Cd), a heavy metal highly toxic to many organisms. Cereal crops such as rice, wheat, maize, and barley are the primary dietary source of Cd for humans, and reducing Cd transfer from soil to their grains is therefore an important issue for food safety. During the last decade, great progress has been made in elucidating the molecular mechanisms of Cd transport, particularly in rice. Inter-and intraspecific variations in Cd accumulation have been observed in cereal crops. Transporters for Cd have been identified in rice and other cereal crops using genotypic differences in Cd accumulation and mutant approaches. These transporters belong to different transporter families and are involved in the uptake, vacuolar sequestration, root-to-shoot translocation, and distribution of Cd. Attempts have been made to reduce Cd accumulation in grains by manipulating these transporters through overexpression or knockout of the transporter genes, as well as through marker-assisted selection breeding based on genotypic differences in Cd accumulation in the grains. In this review, we describe recent progress on molecular mechanisms of Cd accumulation in cereal crops and compare different molecular strategies for minimizing Cd accumulation in grains.     

基于PID直流电机驱动的移动式采摘机器人设计

为了提高移动式采摘机器人的控制效率和移动精度,将直流电机驱动电路引入到采摘机器人移动控制系统的设计中,并采用PID算法对移动速度进行调节,从而避免采摘机器人在移动过程中产生较大的速度波动,提高其作业时的平稳性。为了验证PID算法在采摘机器人移动控制系统上使用的可行性,模拟葡萄采摘机器人的作业环境,对采摘机器人移动过程的速度控制进行了仿真模拟,结果表明:达到速度预定目标时,PID算法比常规算法具有更快的响应速度,调节过程也更加平稳。     

Flavonoid content and radical scavenging activity in fruits of Chinese dwarf cherry (<Emphasis Type="Italic">Cerasus humilis</Emphasis>) genotypes

The Chinese dwarf cherry (Cerasus humilis (Bge.) Sok.) is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the “Chinese Pharmacopeia” and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content (TFC), composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to 72.8 mg/g RE·FW (RE: rutin equivalent, FW: fresh weight) while fruit flesh TFC ranged from 4.3 to 16.9 mg/g RE·FW. An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1 (PA-B1), proanthocyanidin B2 (PA-B2), phloretin 2′-O-glucoside (PG), and phloretin 2′,4′-O-diglucoside (PDG). Principal component analysis showed that PG, PA-B1, and PA-B2 had large, positive factor loading values in the first principal component for each genotype. Increased scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’, ‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.     

诱导始期、温度和历期对松毛虫赤眼蜂滞育诱导及解除滞育的影响

为实现赤眼蜂滞育技术在工厂化生产中的应用,在实验室条件下测定了诱导始期(卵期,幼虫前期、中期、后期,预蛹初期)、温度(8、10、12和14℃)及诱导历期(10、20、30和40 d)对松毛虫赤眼蜂Trichogramma dendrolimi滞育诱导的作用,并对其解除滞育的条件进行了探索。结果表明:松毛虫赤眼蜂从卵期到预蛹初期均可被诱导滞育,以幼虫中期诱导效果最佳。12℃为诱导松毛虫赤眼蜂滞育的最适温度,12℃下诱导滞育20 d,松毛虫赤眼蜂即可进入稳定的滞育状态,滞育率达97.4%。赤眼蜂滞育后,需经过一段时间的低温后才能完成滞育发育。滞育松毛虫赤眼蜂在3℃条件下储藏70 d,解除滞育率达95.9%,3℃条件下经历各储存时间的滞育解除率均高于0℃。     

含水量和容重对旱地耕层土壤热导率的影响及预测

土壤热导率是研究地表能量平衡和土壤水热运移过程中的一个基础参数。受土壤耕作、干湿交替和根系生长等过程的影响,耕层土壤的含水率和结构呈现较强的变异特征,而目前缺乏关于定量分析耕层土壤热导率变异特征的研究。该研究利用田间定位试验,采用热脉冲技术测定了含水率和容重变化条件下耕层土壤热导率的变异特征,并利用传递函数模型对耕层土壤热导率进行了预测。结果表明:含水率和容重是影响耕层土壤热导率变异的主要因子,而耕作强度和干湿交替是这种变异的关键驱动力;与翻耕和旋耕处理相比,免耕处理提高了土壤容重和含水率,从而增大了土壤热导率;在干湿交替作用下,翻耕后土壤容重逐步增加,耕层热导率也呈现上升趋势,波动幅度与含水率的变化相关。基于含水率、容重和质地信息,土壤热导率传递函数模型可以给出可靠的田间土壤热导率估计值,其均方根误差和平均偏差分别为0.09和-0.01 W/(m·K);考虑耕层土壤容重的动态信息,可以提高该模型预测土壤热导率的准确性。     

Straw mulching with fertilizer nitrogen: An approach for improving crop yield,soil nutrients and enzyme activities

Field experiments were conducted to study soil properties, soil enzymes activities, water use efficiency (WUE) and crop productivity after six years of soya bean straw mulching in the semi‐arid conditions of China. The experiment included four treatments: CK (Control), N (240 kg N ha^‐1), H (soya bean straw mulching at half rate 700 kg ha^‐1 with 240 kg N ha^‐1) and F (soya bean straw mulching at full rate 1,400 kg ha^‐1 with 240 kg N ha^‐1). Soil organic carbon (SOC), soil labile organic carbon (LOC), soil available N (AN), available P (AP) and enzyme activities were analysed after wheat harvesting in 2016 and 2017. Results show that straw amounts had positive effects on the soil fertility indices being higher for treatment F. The SOC, LOC, AN, AP and enzyme activities (i.e. saccharase, urease and alkaline phosphatase) were in the order of F > H > N > CK. High wheat grain yield and WUE were observed for F treatment. A total of six years mulching along with 240 kg ha^‐1 nitrogen fertilizer application is sufficient for wheat yield stability and improving soil properties except urease activities in the semi‐arid condition of China. However, the straw mulching amount should be further studied with minimum nitrogen fertilizer for an environment‐friendly and effective approach for improving the soil biological properties with adequate crop production on a sustainable basis in the semi‐arid region of China.     

16份四川小麦生产品种在甘肃陇南抗条锈性表现

小麦条锈病我国小麦生产上的最主要的病害,种植抗病品种是防治该病最经济有效环保的措施。2014—2017年,先后对16份四川省小麦生产品种在甘肃陇南不同生态区的甘谷试验站和汪川良种场两地进行自然诱发鉴定,评价其抗病性。结果发现,所有供试品种均表现感病,川农10号等5份材料具有慢条锈性。     

苦荞粒形相关性状的遗传分析

利用籽粒大小差异较大的2个苦荞品种的杂交后代开展了与产量具有密切关系的粒形相关性状的遗传规律及其性状间的相关性分析。结果表明,F₂和F₃群体的粒长、粒宽、长宽比和千粒重表现值范围都超过亲本的表现值,并且粒长、粒宽和长宽比的变异系数均小于10%,千粒重的变异系数大于10%。另外,粒长、粒宽、长宽比和千粒重的加性方差均大于显性方差,广义遗传率在F₂和F₃代中分别为0.77~0.82和0.82~0.85,固定遗传率都达到0.80以上。粒形性状间的相关性分析结果表明,粒长、粒宽和千粒重相互间都存在极显著的正相关,粒宽和千粒重,粒长和长宽比的遗传相关系数较大。以上结果表明,具有较高遗传率的粒形相关性状可以在后代早期进行选择,但由于这些性状是数量性状而且受多个基因的控制,因此建议继续繁殖后代到基因型稳定,同时考虑性状间的相关性选拔最为有效。     

331份四川小麦品种(系)在甘肃陇南抗条锈性表现及利用价值

2014年-2017年度先后对331份四川省小麦生产品种(系)在温室进行苗期人工接种条锈菌混合菌鉴定和甘谷试验站大田成株期分别接种CYR32、CYR33、CYR34、G22-14、中4-1和混合菌鉴定,同时在甘谷试验站和汪川良种场两地进行自然诱发鉴定。结果发现:在人工接种条件下,苗期、成株期表现抗病的分别有‘XK201465’等36份和‘XK20132’等72份材料,分别占10.88%和21.75%;有‘XK62483’等11份材料全生育期表现抗病,占3.32%;两地三年自然诱发鉴定发现,仅有‘XK20132’等5份材料在两地均表现抗病,有‘川农17’等30份材料具有慢条锈性。对供鉴材料在甘肃陇南的利用前景进行了分析。     

Predicting the potential geographic distribution of Bactrocera bryoniae and Bactrocera neohumeralis(Diptera: Tephritidae) in China using MaxEnt ecological niche modeling

Bactrocera bryoniae and Bactrocera neohumeralis are highly destructive and major biosecurity/quarantine pests of fruit and vegetable in the tropical and subtropical regions in the South Pacific and Australia. Although these pests have not established in China, precautions must be taken due to their highly destructive nature. Thus, we predicted the potential geographic distribution of B. bryoniae and B. neohumeralis across the world and in particular China by ecological niche modeling of the Maximum Entropy(Max Ent) model with the occurrence records of these two species. Bactrocera bryoniae and B. neohumeralis exhibit similar potential geographic distribution ranges across the world and in China, and each species was predicted to be able to distribute to over 20% of the globe. Globally, the potential geographic distribution ranges for these two fruit fly species included southern Asia, the central and the southeast coast of Africa, southern North America, northern and central South America, and Australia. While within China, most of the southern Yangtze River area was found suitable for these species. Notably, southern China was considered to have the highest risk of B. bryoniae and B. neohumeralis invasions. Our study identifies the regions at high risk for potential establishment of B. bryoniae and B. neohumeralis in the world and in particular China, and informs the development of inspection and biosecurity/quarantine measures to prevent and control their invasions.