Changes in concentrations and transcripts of plant hormones in wheat seedling roots in response to Fusarium crown rot

Fusarium crown rot(FCR) is a soilborne disease causing severe yield losses in many wheat-growing areas of the world. Diseased plants show browning and necrosis of roots and stems causing white heads at maturity. Little is known about the molecular processes employed by wheat roots to respond to the disease. We characterized morphological, transcriptional and hormonal changes in wheat seedling roots following challenge with Fusarium pseudograminearum(Fp), the main pathogen of FCR. The pathogen inhibited root development to various extents depending on plants' resistance level. Many genes responsive to FCR infection in wheat roots were enriched in plant hormone pathways. The contents of compounds involved in biosynthesis and metabolism of jasmonic acid, salicylic acid, cytokinin and auxin were drastically changed in roots at five days post-inoculation. Presoaking seeds in methyl jasmonate for 24 h promoted FCR resistance, whereas presoaking with cytokinin 6-benzylaminopurine made plants more susceptible. Overexpression of TaOPR3, a gene involved in jasmonic acid biosynthesis, enhanced plant resistance as well as root and shoot growth during infection.

Root overlap and allocation of above- and belowground growth of European beech in pure and mixed stands of Douglas fir and Norway spruce

Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands.However,mechanisms that may contribute to this effect are rarely studied,even though they are essential to assess the potential of species to cope with climate change.This study examined fine root overlap and the linkage between fine root and stem growth of European beech(Fagus sylvatica)growing in pure and mixed stands with Douglas fir(Pseudotsuga menziesii)or Norway spruce(Picea abies)at two different study sites in northwestern Germany.The study sites represented substantially different soil and climate conditions.At each site,three stands,and at each stand,three pairs of trees were studied.In the pure beech stand,the pairs consisted of two beech trees,while in the mixed stands each pair was composed of a beech tree and a conifer.Between each pair,three evenly spaced soil cores were taken monthly throughout the growing season.In the pure beech stands,microsatellite markers were used to assign the fine roots to individual trees.Changes in stem diameter of beech were quantified and then upscaled to aboveground wood productivity with automatic high-resolution circumference dendrometers.We found that fine root overlap between neighboring trees varied independently of the distance between the paired trees or the stand types(pure versus mixed stands),indicating that there was no territorial competition.Aboveground wood productivity(wood NPP)and fine root productivity(root NPP)showed similar unimodal seasonal patterns,peaking in June.However,this pattern was more distinct for root NPP,and root NPP started earlier and lasted longer than wood NPP.The influence of site conditions on the variation in wood and root NPP of beech was stronger than that of stand type.Wood NPP was,as expected,higher at the richer site than at the poorer site.In contrast,root NPP was higher at the poorer than at the richer site.We concluded that beech can respond to limited resources not only above-but also belowground and that the negative relationship between above-and belowground growth across the study sites suggests an‘optimal partitioning’of growth under stress.

Lateral root elongation in maize is related to auxin synthesis and transportation mediated by N metabolism under a mixed NO_(3)^(–) and NH_(4)^(+) supply

A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are still unclear.Here,maize seedlings were grown hydroponically with three N supplied in three different forms (NO_(3)^(–)only,75/25 NO_(3)^(–)/NH_(4)^(+)and NH_(4)^(+)only).Compared with sole NO_(3)^(–)or NH_(4)^(+),the mixed N supply increased the total root length of maize but did not affect the number of axial roots.The main reason was the increased total lateral root length,while the average lateral root (LR) length in each axle was only slightly increased.In addition,the average LR density of 2nd whorl crown root under mixed N was also increased.Compared with sole nitrate,mixed N could improve the N metabolism of roots (such as the N influx rate,nitrate reductase (NR) and glutamine synthase (GS)enzyme activities and total amino content of the roots).Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation,and whether the NR mediated NO synthesis participates in this process needs further exploration.Meanwhile,an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation,and the changes in the sugar concentration in roots further proved this conclusion.Furthermore,the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation,in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway.This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize,which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.

Root to crown ratio of permanent teeth of people living in Shanghai

The aim of this study is to assess if there is a significant difference between crown to root ratio of male and female permanent teeth in Chinese people in Shanghai.Methods: For this purpose one thousand four hundred (700,male and 700,female) extracted teeth were collected between age 25-35 and the crown length (CL) and root length (RL) of permanent teeth were measured by a precise caliper.Statistical analyses were performed with the SPSS 17 software by Student's t-test method.Results: The mean crown length of permanent teeth of male was found to be larger than that of female except for maxillary central incisor and the mean root length of male was found to be comparatively larger than that of female.Conclusion: There was a significant difference in root to crown ratio (RL/CL) between male maxillary teeth and mandibular teeth and female ones.The RL/CL ratio of male tends to be larger than those of female in Shanghai population.

Segmented taper equations with crown ratio and stand density for Dahurian Larch (Larix gmelinii) in Northeastern China

Segmented taper equation was selected to model stem profile of Dahurian larch （Larix gmelinii Rupr.）. The data were based on stem analysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province, Northeastern China. Two taper equations with crown ratio and stand basal area were derived from the Max and Burkhart’s （1976） taper equation. Three taper equations were evaluated： （1） the original equation, （2） the original equation with crown ratio, and （3） the original equation with basal area. SAS NLIN and SYSNLIN procedures were used to fit taper equations. Fit statistics and cross-validation were used to evaluate the accuracy and precision of these models. Parameter estimates showed that the original equation with inclusion of crown ratio and basal area variables provided significantly different parameter estimates with lower standard errors. Overall fit statistics indicated that the root mean square error （RMSE） for diameter outside and inside bark decreased respectively by 10% and 7% in the original model with crown ratio and by 12% and 7.2% in the original model with basal area. Cross-validation further confirmed that the original equation with inclusion of crown ratio and basal area variables provided more accurate predictions at the lower section （relative heights, 10%） and upper section （relative heights, 50%） for both outside and inside bark diameters.

Does the root to shoot ratio show a hormetic response to stress? An ecological and environmental perspective

Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.

Water Deficit Stress Effects on Corn (<i>Zea mays</i>, L.) Root:Shoot Ratio

A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.

Effects of Free-air CO2 Enrichment on Root Characteristics and C:N Ratio of Rice at the Heading Stage

A hydroponics experiment was conducted to investigate the rice root growth in FACE （free-air carbon dioxide enrichment）. The root biomass, root volume, ratio of root/shoot, number of adventitious roots and root diameter significantly increased under FACE conditions, while the CO2 enrichment decreased the N concentration in rice roots without any change in the C content, leading to an increase in root C：N ratio. Moreover, the elevated CO2 resulted in a remarkable decrease of root activity, expressed as per unit root dry weight, which might be responsible for decreased N concentration in roots.

Crown Ratio and Relative Spacing Relationships for Loblolly Pine Plantations

Two loblolly pine (Pinus taeda L.) culture/density studies were established in 1995-1998 across the Lower Coastal Plain and Upper Coastal Plain/Piedmont regions of the southern USA. Each installation contains 12 plots of loblolly pine planted at six levels of density from 741 to 4448 trees/ha in combination with two levels of cultural intensity, operational and intensive. The data from 37 viable installations were used to evaluate the crown ratio and relative spacing relationship of loblolly pine plantations. The effects of planting density, site quality, and cultural intensity on the relationship were investigated with a nonlinear mixed-effects modeling approach. The crown ratio and relative spacing relationship is exceedingly predictable. When loblolly pine plantation stands reached the average live crown ratio of 0.40, a critical point representing a generally acceptable level of tree vigor, the corresponding relative spacing index ranged from 0.11 to 0.20, mainly depending on initial planting density. The information about the crown ratio and relative spacing relationship would be useful for selecting the best intensity and timing of thinning.

Genetic Diversity of Fusarium solani f. sp. cucurbitae, the Causal Root and Crown Rot of Cucurbits (Melon) by Using Molecular Markers and Control

Detection of F. solani f. sp. cucurbitae causal agent of the crown and root rot disease of melon race 1, race 2 is difficult. It is based only on morphological characteristic. In this study, forty isolates identified as Fusarium solani based on morphological characterization, F. solani was one of the most frequently isolated species. Molecular identification of these isolates by PCR technique using species-specific primer, indicated that thirty-two isolates, amplified product 580 bp (race 1) and two isolate amplified product 580 bp (race 2), while six isolates were not amplified with primer of both races. Production of Trichothecenes (T2-toxen, DON.) by Fusarium solani was conducted on isolates confirmed as belonging in the F. solani by PCR. The results indicated that the presence of Tri5, Tri13 genes is coding the ability of synthesis mycotoxin. In vitro, the results indicated that NPs (AgNPs, MgNPs) and chemical (Phylex) possess the antifungal properties against at various level. Treatment with (AgNPs 150 ppm, MgNPs 2%, 3% ppm) and 3% Phylex resulted in maximum inhabitation of F. solani . In vivo, five characters (height plant, hoot ant root fresh and dry weight) were measured based on the greenhouse, field experimental results. Treatment with (AgNPs, MgNPs) and Phylex had higher measured parameters than positive control.

Differential responses of root growth to nutrition with different ammonium/nitrate ratios involve auxin distribution in two tobacco cultivars

Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to different NH4+/NO3– ratios remains unclear. Two tobacco cultivars(Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO3– nutrition ratio(NH4+/NO3– ratio: 0/100), low NO3– nutrition ratio(NH4+/NO3– ratio: 97/3), and optimal NH4+/NO3– ratio(50/50). We investigated the effects of the different NH4+/NO3– ratios on the formation and elongation of lateral roots(LRs), auxin concentration, DR5::GUS expression, 3 H-labeled indole acetic acid([3 H]IAA) transport, and the expression of six PIN genes in tobacco roots. We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth. The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen(N) accumulation were largely reduced by sole and low NO3– nutrition treatment in NC89, but no difference was observed in Zhongyan 100. In most cases, sole and low NO3– nutrition impaired the elongation and formation of firstorder lateral roots(1° LRs), only in NC89, thus reducing the root growth. IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO3– nutrition media, suggesting that different NH4+/NO3– ratios affect the transport of auxin from leaves to roots. Results were similar following exogenous NAA application to low NO3– nutrition treated seedlings. Based on direct [3 H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO3– nutrition. PIN4 expression levels were markedly decreased in roots of NC89by sole and low NO3– nutrition, while they were unaffected in Zhongyan 100 roots. Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH4+/NO3– ratios via modifying polar transport of auxin.

全瓷冠修复+iRoot SP糊剂根管充填治疗隐裂性牙髓炎患者的临床研究

目的:探究全瓷冠修复联合iRoot SP糊剂根管充填在隐裂性牙髓炎治疗中的应用价值。方法:选取2018年4月—2021年3月厦门大学附属第一医院思明分院收治的78例隐裂性牙髓炎患者,按照治疗方法将其分为常规组和治疗组,患者均予以i Root SP糊剂进行根管充填,常规组39例(患牙46颗)采用烤瓷冠进行牙冠修复,治疗组39例(患牙47颗)采用全瓷冠进行牙冠修复。比较两组治疗效果、疼痛情况、炎症指标水平、牙周情况、咀嚼功能、生活质量。结果:治疗组总有效率为94.87%,高于常规组的79.49%,差异有统计学意义(P<0.05)。术后1周,治疗组视觉模拟评分法(visual analogue scale,VAS)评分优于常规组,差异有统计学意义(P<0.05)。术后1 d两组肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白细胞介素-8(interleukin-8,IL-8)、基质金属蛋白酶-8(matrix metalloproteinase-8,MMP-8)水平升高,但治疗组低于常规组,差异有统计学意义(P<0.05)。两组术后3个月龈沟出血指数(sulcus bleeding index,SBI)、牙龈指数(gingival index,GI)、牙周探诊深度(probing depth,PD)降低,且治疗组低于常规组,差异有统计学意义(P<0.05)。两组术后3个月咀嚼效率、咬合力升高,且治疗组高于常规组,差异有统计学意义(P<0.05)。术后3个月,两组口腔健康影响程度量表(oral health impact profile-14,OHIP-14)评分较术前降低,且治疗组低于常规组,差异有统计学意义(P<0.05)。结论:隐裂性牙髓炎患者iRoot SP糊剂根管充填后采用全瓷冠修复效果显著,能减轻炎症反应,缓解患者疼痛,有助于改善牙周情况,促进咀嚼功能恢复,提高生活质量。

Fusarium pseudograminearum and F.culmorum affect the root system architecture of bread wheat

Yield losses of bread wheat due to crown rot can be more severe when drought conditions occur during the grain-filling period.Root architecture characteristics are important for soil exploration and belowground resource acquisition and are essential for adaptation to water-limited environments.Traits such as root angle,length and density have been strongly associated with acquisition efficiency and contribute to yield stability of the crop.The impact of crown rot pathogens on wheat root architecture is poorly understood.We examined differences in root angle,length and number,as well as dry root weight of the crown rot-susceptible bread wheat cultivar,Livingston inoculated with one of two crown rot pathogens Fusarium culmorum or Fusarium pseudograminearum in a transparent-sided root observation chamber.Significant adverse impacts on plant health and growth were revealed by visual discolouration of the leaf sheaths;fresh and dry shoot weight;leaf area of the oldest and the youngest fully expanded leaf and leaf number.Values of most recorded root system measurements were reduced when inoculated with either F.culmorum or F.pseudograminearum.In contrast,root angle was increased in the presence of F.culmorum but was not significantly changed by F.pseudograminearum.The development of whiteheads and grain losses in bread wheat caused by crown rot have previously been associated with blockages of the vascular systems.The method employed here was able to identify differences in the pathogen impacts on roots,which were not detected using previous systems.This research indicates that in the presence of F.culmorum and F.pseudograminearum infection,not only reductions in the size and biomass of the shoot system but also changes in the length,biomass and architecture of the root system could play an important role in yield loss.

Phytophthora Root and Crown Rot on Fruit Trees in Bulgaria

Phytophthora root and crown rot was found on the fruit trees in Bulgaria for the first time in the period 1998-1999. Monitoring of the disease spread from 2000 to 2007 points out incidence between 2 and 14 per cent, in some orchards and nurseries in the Southern part of Bulgaria. The following Phytophthora species were identified based on morphological and cultural characteristics, and temperature requirements： Phytophthora cactorum, Phytophthora citrophthora, Phytophthora drechsleri, Phytophthora cryptogea, Phytophthora hybrid specie and Pythium. Prevailing specie was P. cactorum. P. cryptogea and P. cactorum were confirmed by application of molecular methods. Nutritional requirements of P. cactorum and P. citrophthora were studied. Most Nitrogen sources stimulated the mycelial growth of P. cactorum to a higher extend, and reduced the colony size ofP. citrophthora. Different Carbon sources were utilized well by P. cactorum, and only saccharose and maltose had a stimulating effect on the mycelial growth of P. citrophthora. MgSO4.7H20 was the preferred sulfur source for both fungi, as L-cysteine and L-methionine only for P. cactorum. Phytophthora infection leads to physiological changes in the.host plant tissues. The tendency traced out is： about disorders in the amino acid metabolism, increase in the total sugars and slight reduction of the cellulose content. The total nitrogen, phosphorus and potassium content are reduced and the calcium and magnesium are increased. Photosynthesis of inoculated plants was suppressed and transpiration was increased.

iRoot SP冷侧压法与热牙胶垂直加压法在C形根管充填治疗牙体牙髓病患者中的应用效果比较

目的:比较iRoot SP冷侧压法与热牙胶垂直加压法在C形根管充填治疗牙体牙髓病患者中的应用效果。方法:选取2021年1月至2021年12月该院收治的60例牙体牙髓病患者进行前瞻性研究,按照随机数字表法将其分为对照组和观察组各30例。两组均进行C形根管充填治疗,对照组采用热牙胶垂直加压法,观察组采用iRoot SP冷侧压法,比较两组充填效果(适填率、充填面积比),随访6个月时临床疗效,治疗前和治疗后1、2、3 d疼痛程度[数字评价量表(NRS)]评分,不良反应发生率,以及随访6个月时复发率。结果:两组适填率、充填面积比、治疗总有效率比较,差异均无统计学意义(P>0.05);治疗后1、2、3 d,观察组NRS评分均低于对照组,差异有统计学意义(P<0.05);观察组不良反应发生率为10.00%(3/30),低于对照组的33.33%(10/30),差异有统计学意义(P<0.05);观察组复发率为3.45%(1/29),低于对照组的28.57%(8/28),差异有统计学意义(P<0.05)。结论:iRoot SP冷侧压法行C形根管充填治疗牙体牙髓病患者,可减轻疼痛程度,减少不良反应,降低复发率,但充填效果和临床疗效与热牙胶垂直加压法相当。

二氧化锆髓腔固位冠修复低牙合龈距磨牙的临床效果

目的 评估二氧化锆髓腔固位冠修复低牙合龈距磨牙的临床效果。方法 对2020年1月—2022年1月就诊的46例(50颗)根管治疗后的低牙合龈距磨牙采用二氧化锆髓腔固位冠修复。分别于修复完成后1、6、12个月复查,对修复体完整性、邻接紧密度、边缘密合情况、基牙情况、牙周状况及修复体松动或脱落情况进行评估。结果 1个月复查,50颗磨牙修复后各项评价指标均达到临床可接受水平。6个月复查,6颗患牙牙龈轻度充血,修复体及基牙牙体无异常。12个月复查,仅2颗患牙修复体邻接关系欠佳;2颗患牙牙龈轻度充血,未发现修复体及基牙牙体问题。结论 对根管治疗后的低牙合龈距磨牙采用二氧化锆髓腔固位冠修复既可保护牙体避免折裂,又可提升黏结效果且兼具美观,临床应用效果良好。

社区人群心内膜下心肌活力率的影响因素研究

背景心血管疾病目前在全球范围仍然有很高的发病率和死亡率。心内膜下心肌活力率(SEVR)是侵入性血流动力学研究中分析左心室和主动脉压力曲线引出的一个指标,是评估心肌灌注的一个有价值的工具,在不同人群的心血管不良事件和死亡率方面也具有潜在的预测价值。无创的测量方法可以估测SEVR,虽然有一定局限性,但仍然是评估心肌灌注和心血管风险的有价值的工具并显示出了巨大的临床应用潜力。目前缺乏大规模流行病学调查研究探索SEVR在心血管疾病一级和二级预防中的实际价值。目的在北京社区人群中使用无创方法估测SEVR,并分析其相关影响因素。方法本文基于队列研究的横断面随访,研究对象来源于北京大学第一医院心血管内科2011年12月—2012年4月在北京市石景山区首钢社区建立的动脉粥样硬化研究队列,招募人群为年龄≥40岁的社区居民。2018年随访时采用无创方法进行脉搏波分析检查,并获得SEVR结果。采用线性回归分析探究SEVR的相关影响因素。结果2018年参加随访的6568例研究对象中,排除因心律不齐等未能完成脉搏波分析检查获得SEVR者,最终入选6382例,97.2%的研究对象有SEVR结果。6382例社区居民中男2130例、女4252例,平均SEVR为(144±22)%。线性回归分析结果显示,在总社区居民中,性别(β=-11.00)、年龄(β=-0.53)、吸烟(β=2.36)、高血压(β=-4.12)、脂代谢紊乱(β=-1.45)、糖尿病(β=-4.36)、服用降压药(β=3.72)、降糖治疗(β=-3.71)是SEVR的独立影响因素(P<0.05)。在男性居民中,年龄(β=-0.67)、高血压(β=-3.20)、脂代谢紊乱(β=-2.73)、糖尿病(β=-3.42)及降糖治疗(β=-5.07)是SEVR的独立影响因素(P<0.05)。在女性居民中,年龄(β=-0.48)、吸烟(β=9.44)、高血压(β=-4.98)、糖尿病(β=-4.95)、服用降压药(β=5.26)及降糖治疗(β=-2.82)是SEVR的独立影响因素(P<0.05)。结论无创的SEVR测定在大规模社区人群的队列研究中应用是可行的。SEVR与性别、年龄、吸烟、高血压、脂代谢紊乱、糖尿病这些传统冠心病危险因素相关,其与药物治疗的关系还需要进一步研究探讨。

不同时期水分胁迫对大豆根系特性及产量的影响

为揭示抗旱基因型大豆根系应答干旱胁迫的响应机制,于2020年在辽宁省沈阳市开展盆栽试验,以抗旱基因型和干旱敏感型大豆为试材,探讨干旱(W1,土壤含水量为田间持水量的50%)、轻度干旱(W2,土壤含水量为田间持水量的60%)、适宜水分(W3,土壤含水量为田间持水量的80%)对大豆根系特性和产量的影响。结果表明:同一时期控水,W1和W2条件下,抗旱品种“辽豆14”的总根长和根表面积优于干旱敏感型品种“辽豆21”。一般情况下,平均根直径为0~0.5 mm的根长比例表现为:“辽豆21”>“辽豆14”,而平均根直径为0.5~1.0 mm的根长比例却表现为:“辽豆14”>“辽豆21”。随着生育进程的推进,大豆地上部鲜重、地上部干重、根干重逐渐累积,鼓粒期达最大值;一般情况下,同一控水时期,随着土壤含水量的增加,同一品种地上部鲜重、根鲜重、地上部干重、根干重值逐渐增加,但抗旱品种“辽豆14”的值一般优于干旱敏感型品种“辽豆21”。随着生育进程的推进,根冠比鲜重和根冠比干重值降低;土壤干旱提高了植株的根冠比。各个时期控水,品种和水分均显著影响了大豆的单株产量,干旱(W1)和轻度干旱(W2)均降低了2品种的单株产量,但抗旱品种“辽豆14”引起产量下降的值更低。干旱胁迫条件下,抗旱基因型大豆在总根长、根表面积、地上部干重、根干重、产量以及平均根直径为0.5~1.0 mm的根长比例方面,表现出优于干旱敏感型品种的优势。

影响‘红满堂’绿枝插条生根因子的研究

[目的]研究扦插基质、插穗部位、生长调节剂及生长调节剂处理时间对‘红满堂’品种绿枝扦插生根效果的影响,筛选绿枝扦插的适宜组合,可为其工厂化育苗提供理论依据和技术支撑。[方法]以‘红满堂’品种当年生绿枝为材料,采用L9(34)正交试验设计,从扦插后3 d开始,每3~4 d观察插穗基部变化,并记录插穗生根状况,在扦插50 d时,调查不同处理水平下插穗的生根率以及不定根数量、不定根均长和最长根长,综合评价生根效果。[结果]影响‘红满堂’品种绿枝扦插生根的主导因子是插穗部位,同一枝条发育充实、木质化程度相对较高的中、下部位插穗的生根率(36.67%、40.67%)显著高于上部插穗(9.33%)。生长调节剂的种类、浓度和处理时间长短是影响扦插繁殖的关键因素,对扦插繁殖的生根率、不定根条数、不定根均长、最长不定根长和生根效果综合评价值均有极显著影响,不同生长调节剂和时间处理‘红满堂’绿枝扦插的生根率、不定根条数、不定根均长、最长不定根长、生根效果综合评价值分别为14.67%~38.00%和23.33%~36.00%、2.40~5.03条和3.40~4.57条、1.93~2.27 cm和1.10~2.93 cm、2.47~3.41 cm和1.66~3.39 cm、43.70%~86.40%和56.00%~81.07%。扦插基质显著影响不定根的生长发育,不同基质的不定根条数、不定根均长、生根效果综合评价值分别为3.37~5.00条、1.34~3.10 cm、58.43%~76.37%。[结论]‘红满堂’品种绿枝扦插属综合生根类型,以愈伤组织生根类型为主。绿枝插穗生根最佳处理组合为:采用当年生绿枝下部做插穗,用生长调节剂IBA(吲哚丁酸)2500 mg·L^(-1)浸蘸插穗基部20 s,扦插于椰糠∶蛭石∶珍珠岩(1∶2∶4)的基质中。根系发育最佳的处理组合为:采用当年生绿枝的中间部位做插穗,用生长调节剂IBA 2500 mg·L^(-1)浸蘸插穗基部5 s,扦插于草炭∶蛭石∶珍珠岩(1∶2∶4)的基质中。

番茄颈腐根腐病病原菌鉴定及抗性品种筛选

番茄颈腐根腐病是设施番茄冬春生产中最严重的病害之一,严重威胁我国设施番茄的安全生产。近年来番茄颈腐根腐病在我国番茄主产区发生日益严重,培育抗病品种是防治该病最经济有效的方法。本试验采集典型症状的发病植株进行病原菌分离纯化,综合运用形态学观察、分子生物学鉴定和致病性测定方法,确定病原菌为尖孢镰刀菌番茄颈腐根腐病专化型(Fusarium oxysporum f.sp.radicis-lycopersici,Forl)。之后利用分离的病原菌通过苗期人工接种鉴定结合抗性基因分子标记方法,对32个番茄商品种进行抗颈腐根腐病鉴定分析,结果显示有18个表现抗病,与分子标记Frl-ZL的鉴定结果一致,可用于番茄抗颈腐根腐病育种或生产。