草地土壤分离能力季节变化特征及其影响因素

土壤分离能力是土壤侵蚀机理模型的重要参数.受土壤性质、植被根系等因素影响,土壤分离能力呈现显著的季节变化.为研究草地土壤分离能力季节变化特征及其影响机制,以建植一年的柳枝稷、无芒雀麦草地及对照裸地为研究对象,以20 d为周期,测定土壤密度、黏结力和根系密度,并采集原状土样进行水槽实验(τ=6.5-23.4Pa),测量土壤分离能力,并运用相关分析、回归分析等方法,研究土壤性质及植被根系对土壤分离能力季节变化的影响.结果显示:柳枝稷和无芒雀麦草地具有类似的季节变化特征,而裸地与二者差异明显.4月中旬至6月下旬,草地土壤分离能力较大,此后土壤分离能力迅速下降;7月中旬直至10月上旬,草地土壤分离能力较低;10月下旬,土壤分离能力小幅回升;裸地土壤分离能力7、8月份较低,其余时间较高.裸地土壤分离能力试验期均值为柳枝稷草地的10.6倍,无芒雀麦草地的23.7倍.草地土壤分离能力的季节变化受根系密度和土壤黏结力的影响,随着根系密度与土壤黏结力增大,土壤分离能力呈指数形式降低,而土壤密度对土壤分离能力季节变化的影响并不显著.试验区内草地土壤分离能力可用水流剪切力、根系密度、根径和土壤黏结力等参数进行模拟(R2=0.636).研究结果可为土壤侵蚀机理模型的推广应用,以及小流域水土保持措施配置等工作提供科学依据.     

Nutrient availability and corn growth in a poultry litter biochar‐amended loam soil in a greenhouse experiment

Nutrient‐rich biochar produced from animal wastes, such as poultry litter, may increase plant growth and nutrient uptake although the role of direct and indirect mechanisms, such as stimulation of the activity of mycorrhizal fungi and plant infection, remains unclear. The effects of poultry litter biochar in combination with fertilizer on mycorrhizal infection, soil nutrient availability and corn (Zea mays L.) growth were investigated by growing corn in a loam soil in a greenhouse with biochar (0, 5 and 10 Mg/ha) and nitrogen (N) and phosphorus (P) fertilizer (0, half and full rates). Biochar did not affect microbial biomass C or N, mycorrhizal infection, or alkaline phosphomonoesterase activities, but acid phosphomonoesterase activities, water‐soluble P, Mehlich‐3 Mg, plant height, aboveground and root biomass, and root diameter were greater with 10 Mg/ha than with no biochar. Root length, volume, root tips and surface area were greatest in the fully fertilized soil receiving 10 Mg/ha biochar compared to all other treatments. The 10 Mg/ha biochar application may have improved plant access to soil nutrients by promoting plant growth and root structural features, rather than by enhancing mycorrhizal infection rates.     

从天葵药材的解剖结构探讨其形态本质

天葵"块根"是由主根及下胚轴共同膨大形成,天葵药材的形态本质应为肉质直根。天葵肉质直根的增粗主要原因是由于木薄壁细胞产生三生形成层,形成大量三生维管束;以及次生韧皮部和次生木质部中薄壁细胞的不断增加。     

hrpZ_(Psta)在转基因大豆中定量表达与疫霉根腐病和灰斑病抗性相关研究

以T5转hrpZPsta基因大豆JN29-705-15和JL30-187为材料,利用实时荧光定量PCR技术(Quantitative Real Time PCR,qRT-PCR)检测了目标基因在转基因大豆不同组织中的表达量,分别利用下胚轴侵染法和叶面喷施法鉴定疫霉根腐病抗性和灰斑病抗性,并分析目的基因表达量与疫霉根腐病和灰斑病抗性的相关性。结果表明:hrpZPsta基因在大豆的叶、茎、根、籽粒中均有表达,二个株系平均相对表达量分别为8.2/6.1、0.9/0.7、6.5/4.6和0.8/0.7;T5转hrpZPsta基因大豆抗疫霉根腐病和灰斑病能力与野生型相比均有所提高,JN29-705-15对疫霉根腐病抗性从感病提高到中抗,而JL30-187从中抗提高到抗病;hrpZPsta基因在叶中的表达量也与抗灰斑病能力呈正相关,与病情级别呈极显著负相关。试验结果初步证明了外源基因hrp ZPsta在大豆植株中的表达量与受体植株对疫霉根腐病和灰斑病抗性存在一定的相关性。     

Root zone temperature alters storage root formation and growth of sweetpotato

Large mounds amended with plant residues are a common cultivation method for sweetpotato (Ipomoea batatas) in the western parts of the Papua New Guinea highlands, with a suggested benefit of elevated root zone temperature (RZT) from decomposition. This study aimed to evaluate whether RZT affects the formation and growth of sweetpotato storage roots. Experiments evaluated the effects of a constant elevated RZT on the Beauregard cultivar and of a short‐term increase in RZT on the Beauregard and Northern Star cultivars. Plants were grown in 18‐L pots divided into a control compartment (constant RZT at 20°C) and a treated compartment (RZT at 30, 40 or 50°C). Constant elevated RZT was maintained until harvest, while short‐term increase in RZT occurred in weeks 2 and 3 only. Constant elevated RZT did not affect the total number of storage roots, but RZT of 30°C and above reduced the dry‐biomass of storage roots. The short‐term increase in RZT did not alter the total number or dry‐biomass of storage roots in Beauregard, while both of these attributes were reduced at RZT of 40°C or above in Northern Star. Elevated RZT inhibited dry‐biomass accumulation of storage root, with a more pronounced impact at constant elevated RZT. These results demonstrate that any benefits of the mound culture on sweetpotato yield production do not arise through the influence of temperature elevation.     

不同用量松土促根剂对冬小麦产量的影响

研究了Agri-Star松土促根剂在冬小麦上的合理用量,为该产品大面积推广提供依据.结果表明,在正常旋耕施肥(配方肥750 kg/hm2+旋耕12 cm,CK2)的基础上,获得最高产量的松土促根剂施用量为18.13 kg/hm2,最佳经济施用量为16.87 kg/hm2,施用松土促根剂13.5 kg/hm2处理较CK2平均增产26.18％.施Agri-Star松土促根剂是小麦生产上值得推广的新技术.     

铲头堆砂白蚁原始繁殖蚁形成的周期

铲头堆砂白蚁Cryptotermes declivis Tsai et Chen是破坏木材及木制品的重要干木白蚁,其有翅成虫通过分飞配对后建立新群体,是其重要繁殖扩散途径。本文对铲头堆砂白蚁原始繁殖蚁形成周期进行了研究。以似桂木Paratocarpus sp.、团花Anthocephalus chinensis(Lam.) Rich. et Walp.和球花豆Parkia sp.作为该种白蚁食料,研究其原始繁殖蚁配对后从新建群体的形成到产生下一代的原始繁殖蚁,完成1个世代生活周期。结果表明,铲头堆砂白蚁在室温下,新建群体的形成、发展、发育至下一代原始繁殖蚁形成的周期约5 a,不同寄主材料对铲头堆砂白蚁生活周期没有显著性影响,但与群体数量多少显著相关。本研究首次明确了铲头堆砂白蚁群体发育成熟的周期,对该害虫的检疫与防控研究具有重要参考价值。     

影响静止中心(QC)细胞分裂的EMS突变体库构建与筛选分析

采用正向遗传学方法,以转基因拟南芥(Arabidopsis)SCRGVG UAS∶∶axr3-1为材料来进行EMS诱变。通过外源施加激素DEX诱导GVG/UAS系统启动axr3-1在静止中心表达,导致静止中心发生分裂。通过构建EMS突变体库,得到2 616份M2代候选突变体家系。对M2代种子进行初筛得到43个候选家系。经过复筛,获得22个具有稳定表型的突变体家系。根据表型相似性将候选家系分为5类,共6组。将候选家系进行组内杂交,根据F1代植株表型是否与亲本相似,获得2对等位突变体。这些突变体将为研究干细胞小生境的调控机制研究提供新材料。     

浅析灌溉对作物根系及产量的影响

结合文献资料,从作物根系的水平分布、垂直分布、硝态氮运移及产量等几个方面,概述了不同灌溉量和灌溉方式对作物的影响,分析了滴灌、渗灌等微灌技术的应用。最后,针对经济林木生产的实际现状,进行了展望：探索一种成本低、简单易操作、便于推广应用的灌溉措施更具有理论和实践意义。     

Effect of the Substrates on the Production of Engrafted Vine Cuttings in Heated Greenhouses

This article highlights the results of a long-term research project on the production of grape stalks engrafted by the desk method. The integrated impact of rootstock varieties, modes of stratification, and different substrates on vegetating vine cuttings, raised in heated greenhouses, and the capacity of their acclimatization after planting was studied. The results of the research show that rootstock variety and modes of stratification influence the output of engrafted vegetating cuttings of vines grown in pots using various substrates. In particular, the engrafted cuttings of variety Rkatsiteli produced on two rootstocks, 5 BB and 101-14, passed stratification (a) in sawdust with local electroheating, (b) on the water with its periodic change, and (c) in the layer of perlite. After preplanting preparations they were planted in pots with six different substrates: (1) soil (control); (2) perlite; (3) sawdust; (4) rice husk + soil + sand (1:1:1); (5) peat + soil + sand (1:1:1); and (6) mold + soil + sand (1:1:1). The cuttings were grown with a covered root system in a heated greenhouse for 35–40 days. Forty-day-old vegetating cuttings, after hardening, were planted into the open ground. Specialties were established during the root and shoot formation on vegetating nursery plant grafts during the rooting period. Optimal substrates for growing engrafted cuttings with a covered root system in heated greenhouses for each rootstock and stratification mode were determined.