迟播对冬小麦灌浆后期高温胁迫下旗叶光合能力和产量的影响

为了解迟播对冬小麦灌浆后期高温胁迫下旗叶光合的调控效应,在大田条件下设置2个播期(常规播期10月8日、推迟播期10月22日)和2种灌浆期温度(开放式增温、自然温度),分析了迟播小麦旗叶光合能力的变化及其对灌浆后期高温胁迫的响应。结果表明,灌浆期高温降低了小麦旗叶光合速率、花后干物质生产量、粒重和产量。与常规播期相比,迟播提高了高温胁迫下小麦旗叶叶绿体类囊体膜不饱和脂肪酸指数,保持类囊体膜相对稳定,减轻高温对旗叶光合机构的损伤;增强了旗叶活性氧清除能力,保障能量传输,减少热耗散,提高光化学反应中可利用能量的分配比例,保持较高的光合系统同化力;提高了气孔导度和胞间CO_2浓度,增加光合作用底物供应。总之,迟播小麦的旗叶可在灌浆期高温胁迫下保持较高的光合能力,有利于提高粒重和产量。     

氮素追肥后移对小麦籽粒产量和旗叶光合特性的影响

用4个小麦品种，研究了高产水平下氮素追肥后移对小麦群体结构、籽粒产量和旗叶光合特性的影响，在基肥量相同的情况下，每公顷追施氮素150kg，追肥由越冬至返青期（N1），延迟到返青至拔节期（N2）和拔节至孕穗期增加籽粒产量的作用，其效果N3处理优于N2处理。     

延迟投饵对真鲷,牙鲆仔鱼早期阶段摄食,存活及生长的影响

试验结果表明：（１）２日龄真鲷,牙鲆仔鱼初次摄食,在６￣７日龄和５￣６日龄,不能建立外源性营养的仔鱼分别进入ＰＮＲ期,而卵黄囊均在此前１￣２天已耗尽。混合营养期分别为３￣４天和１￣２天。（２）真鲷和牙鲆仔鱼在不同饥饰饿阶段初次摄食率的变化式型是：开始较低,此后逐步上升,高峰期出现在卵黄囊接近耗尽时,此后开始下降。记录到的最高初次摄食率分别为８６．７％和３５％。（３）牙鲆仔鱼体长的增长率随延迟投饵天     

不同程度火烧迹地兴安落叶松延迟性死亡特征

在2018年汗马国家级自然保护区火烧迹地按不同火烧程度设立9个标准样地(30 m×30 m),以样地内760株延迟性死亡兴安落叶松为全部样本,划分为7个径级,分析不同程度火烧迹地不同径级的兴安落叶松(Larix gmelinii(Rupr.)Kuzen)延迟性死亡特征。将全部样本的80%(610株)作为建模样本,20%(150株)作为检验样本,使用Logistic回归方程对兴安落叶松延迟性死亡率进行预测。结果表明:轻度火烧样地中,兴安落叶松延迟性死亡率随着径级的增加而逐级降低,降低幅度分别为8.5%、28.5%、17.4%,胸径大于20 cm的树木延迟性死亡率为0;在所有延迟性死亡树木中,胸径小于10 cm的树木占76.8%。中度火烧样地中,兴安落叶松延迟性死亡率随径级的增加也逐级降低,但降低幅度没有轻度火烧样地明显,胸径大于25 cm的树木延迟性死亡率为0;在所有延迟性死亡树木中,胸径6~15 cm的树木占86.8%。重度火烧样地中,兴安落叶松延迟性死亡率明显升高,最低为66.7%,最高为100%,胸径为26~35 cm的树木没有发生延迟性死亡。火烧程度与径级对兴安落叶松延迟性死亡的影响均极显著(P<0.01),火烧程度与径级的优势比值分别为3.208和0.725。预测发生延迟性死亡的准确率为71.7%,预测为未发生延迟性死亡的总样本的准确率为60.4%。总样本A_U,C值为0.764,说明预测模型准确率较高,拟合效果良好。     

Fruit quality and nutrient composition of grapevines: a review

Grape quality and its nutrient composition vary depending on agronomical management practices (fertilization, irrigation, weed, and pest control), and agrochemicals treatments (such as kaolin, hormones, and sucrose), viticultural (grape cultivars and varieties, training, pruning, cluster thinning, and trunk girdling), and biotechnological techniques, as well as growth stage and environmental changes (soil, climate, and season). Understanding the mentioned agro-biotechnological techniques assists grape growers and geneticists in breeding grapevines to improve yield, tolerance, quality, and nutraceutical values based on their usage purposes. Thus, this review article focuses on the up-to-date approaches and incentivizes further studies on the unknown mechanisms related to engineering grape flavonoid/phenylpropanoid biosynthetic pathways to improve its health-promoting effects in both grape and human. The engineering/breeding strategies and viticultural practices have been proposed based on the grape usage purposes and environmental conditions.     

The Occurrence of Delayed Stem Senescence in Relation to trans-Zeatin Riboside Level in the Xylem Exudate in Soybeans Grown under Excess-Wet and Drought Soil Conditions

Abstract

Delayed stem senescence (DSS) after pod maturation in soybean (Glycine max) lowers the quality of products in the mechanized harvest. The effects of drought and excess wet soil conditions on the occurrence of DSS were studied with special reference to remobilization of vegetative nitrogen and supply of cytokinin via xylem. Excess wet soil treatment was applied throughout the reproductive period to field-grown soybean in 2003 (Exp.1) and short-term drought stress treatment was applied during the reproductive period to pot-grown soybean plants in 2004 (Exp.2). The degree of DSS at pod maturing was evaluated by the DSS score from “1” for severe DSS to “5” for completely synchronous senescence of pods and vegetative parts. The DSS score in Exp.1 varied from 2.2 to 2.5 and that in Exp.2 from 2.8 to 3.7. Excess wet soil treatment in Exp.1 promoted the occurrence of DSS, while drought stress treatments during the periods of flowering to pod elongation, later seed-filling and seed maturing decreased it. The soybean plants that showed distinct DSS had lower ratios of seed number to vegetative dry weight at seed maturity and a lower rate of nitrogen remobilization from vegetative organs to seeds during the latter half of the reproductive period. The trans-zeatin riboside (t-ZR) level in xylem exudate tended to be higher in soybeans with severer DSS than in those normally matured in both experiments showing increased t-ZR concentration and/or higher exudation rate. These results suggest that DSS can be caused by a wet soil water condition, which lowers pod/seed number and increases vegetative organs mediated by the increased supply of cytokinin through xylem during seed-filling.     

Varietal Difference in the Occurrence of Delayed Stem Senescence and Cytokinin Level in the Xylem Exudate in Soybeans

Abstract

The objectives of this study were to evaluate the varietal difference in the occurrence of delayed stem senescence (DSS) and cytokinin level in the xylem exudate in soybeans and the relationship between the occurrence of DSS and cytokinin level in the xylem exudate. Pot experiments were carried out in the experiment field at Nihon University in 2010, 2012 and 2013. In this experiment, we used 11 soybean varieties, which were cultivated in the Kanto region, Japan. The degree of DSS (DSS score) was positively correlated with the days from sowing to flowering stage (S-R2), and was higher in the varieties with a longer length of S-R2, though the correlation was not significant. Under some conditions, the DSS score was negatively correlated with S-R2. Moreover, the DSS score was positively or negatively correlated with the main stem diameter, total node number, stem dry weight and seed weight depending on the growth parameter or sowing date. Thus, we concluded that the DSS score was not correlated with the growth parameters. On the other hand, the level of cytokinins such as t-ZR and iPA shown by their amount in xylem exudate from a plant at the seed filling stage was negatively correlated with the DSS score. Thus, we consider that one of the reasons for varietal difference in DSS occurrence may be the difference in cytokinin content of stem and leaves after the seed filling stage.     

基于无线传感器网络的葡萄栽培环境监测系统

为了实现对南方地区设施葡萄关键环境参数的监控,降低农艺人员劳动强度,提出一种结合分层结构的WSN网络和Wi-Fi技术的葡萄栽培监测系统.采用CC2530无线发射芯片为核心构造了采集节点,进行了相应的软硬件设计,完成对空气温湿度、土壤温湿度等参数的实时采集.为了解决节点定位的问题,结合葡萄栽培要求,采用了基于虚拟单元格的网络结构,优化了单元格簇头选举机制,结合分层方法完成多跳传输,并采用了自动重传纠错机制.与典型LEACH-C算法相比,改进算法的网络节点死亡率降低约23%.结合多点接入的Wi-Fi技术扩展了系统监控范围,上位机监测系统操作直观,能实时监测葡萄生长过程中参数变化情况,并根据专家经验库自动报警和指示操作.系统运行稳定可靠,能较好地满足种植管理的需要.