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.

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.

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.

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。

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。

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。

孕晚期血清尿酸及血清尿酸/肌酐水平与不良妊娠结局的关系研究

背景孕期血清尿酸代谢紊乱与不良妊娠结局相关,但目前分析并比较血清尿酸及血清尿酸/肌酐水平在孕期不良妊娠结局中的关系研究较少。目的分析孕妇孕晚期血清尿酸及血清尿酸/肌酐水平与不良妊娠结局的关系。方法选取2015—2022年于南京大学医学院附属鼓楼医院常规产检及生产的单胎活产孕妇743例为研究对象。根据是否发生不良妊娠结局,将孕妇分为正常组344例和不良结局组399例。分别以四分位数将血清尿酸及血清尿酸/肌酐分为3个水平:Q1(血清尿酸<257μmol/L)、Q2(血清尿酸257~359μmol/L)、Q3(血清尿酸>359μmol/L)和q1(血清尿酸/肌酐<5.88)、q2(血清尿酸/肌酐5.88~7.94)、q3(血清尿酸/肌酐>7.94)。根据孕妇中位年龄,将孕妇分为年龄<30岁亚组(341例)及年龄≥30岁亚组(402例)。根据既往孕产次情况,将孕妇分为初产妇亚组(539例)及经产妇亚组(194例)。采用多因素Logistic回归分析探讨血清尿酸及血清尿酸/肌酐水平与不良妊娠结局的关系。结果不良结局组孕妇年龄、BMI、血清尿酸、血清尿酸/肌酐、三酰甘油高于正常组(P<0.05)。校正混杂因素后,血清尿酸、血清尿酸/肌酐对不良妊娠结局影响的多因素Logistic回归分析结果显示,与Q1水平血清尿酸相比,Q3水平时子痫前期(AOR=4.41,95%CI=2.16~8.99)、宫内生长受限(AOR=3.59,95%CI=1.08~11.96)的发生风险增加(P<0.05);与q1水平血清尿酸/肌酐相比,q2、q3水平时子痫前期(AOR=2.33,95%CI=1.13~4.79;AOR=3.56,95%CI=1.68~7.56)的发生风险增加,q3水平时早产(AOR=2.76,95%CI=1.33~5.71)、宫内生长受限(AOR=5.15,95%CI=1.39~19.14)的发生风险增加,而q3水平时巨大儿(AOR=0.43,95%CI=0.19~0.98)、大于胎龄儿(AOR=0.38,95%CI=0.15~0.96)的发生风险降低(P<0.05)。血清尿酸、血清尿酸/肌酐在不同年龄亚组对子痫前期、早产的影响结果显示,与Q1水平血清尿酸相比,Q3水平在两个年龄亚组中子痫前期的发生风险均增加(P<0.05);与q1水平血清尿酸/肌酐相比,q2、q3水平在年龄≥30岁孕妇中子痫前期的发生风险增加(P<0.05)。血清尿酸、血清尿酸/肌酐在不同孕产次亚组对子痫前期、早产的影响结果显示,与Q1水平血清尿酸相比,Q3水平在初产妇中子痫前期的发生风险增加(P<0.05);与q1水平血清尿酸/肌酐相比,q2、q3水平在初产妇中子痫前期的发生风险增加,q3水平在初产妇中早产的发生风险增加(P<0.05)。结论高水平血清尿酸、血清尿酸/肌酐时子痫前期、宫内生长受限的发生风险均增加,其中子痫前期主要发生在年龄≥30岁的孕妇或初产妇中。高水平血清尿酸/肌酐时早产的发生风险增加,主要发生在初产妇中。血清尿酸/肌酐较血清尿酸预测的不良妊娠结局更多。

三次CVC、五次CVC及SmartCrown辊形控制特性对比研究

通过对三次连续变凸度(continuously variable crown,CVC)、五次CVC及SmartCrown三种辊形方程进行推导分析,得出了各自的板形控制特性,提出了各自的辊形设计方法。研究表明:三次CVC只具备二次凸度控制能力,控制特性简单;五次CVC可根据二次及四次凸度控制需要灵活设计,凸度比在窜辊过程中并非恒定;SmartCrown四次凸度控制能力受形状角影响,凸度比恒为负值。

播期推迟对棉花根系生长发育特征及产量的影响

【目的】研究推迟播期对棉花根系生长发育特征和产量的影响,为黄河流域棉区棉花适期播种提供依据。【方法】2022―2023年在河北农业大学威县试验站开展田间试验,设置常规播期(4月15日)和推迟播期(5月1日)2个处理,分析推迟播期对棉花品种冀农大23号的根系分布、根系生长速率、根冠比、干物质积累量和产量等的影响。【结果】与常规播期相比,推迟播期条件下,棉花根系长度和生物量的最大增长速率分别增加2.92~5.35 cm·d^(-1)和0.40~0.76 mg·d^(-1);深层土壤中棉花根系占比提高,其中30~60 cm土层根系长度占比和根系生物量占比分别增加2.99~3.55百分点和3.94~4.42百分点;生育后期棉株地上部干物质积累量和根冠比无明显差异;根系载荷能力显著降低6.43%~17.69%;2022年籽棉产量无显著差异,2023年单位面积铃数和籽棉产量分别显著增加9.72%和7.66%。相关分析表明,0~60 cm土层根长密度、0~60 cm土层根系生物量密度、根系生物量最大增长速率和30~60 cm土层根系长度占比均与籽棉产量极显著正相关。【结论】黄河流域棉区推迟播期(5月1日)可通过提高棉花根系生长速率、深层土壤中根系长度和根系生物量的占比,增强根系吸收功能以保障地上部干物质的积累,促进棉花高产。

不同浓度矮壮素、萘乙酸和烯效唑对大葱苗期生长的影响

为探究不同植物生长调节剂对大葱苗期徒长的控制效果,研究了矮壮素、萘乙酸和烯效唑3种植物生长调节剂对大葱苗期生长的影响。结果表明,喷施3种植物生长调节剂均能显著增加大葱幼苗的根系数量、茎粗、壮苗指数和根冠比;矮壮素和烯效唑处理显著降低株高,萘乙酸处理则增加株高;矮壮素和萘乙酸处理的叶绿素含量增加,干质量增加,而喷施不同浓度烯效唑的叶片和假茎干质量在处理后35 d时分别较对照降低7.56%~31.59%和27.95%~47.33%。综合考虑大葱幼苗的形态指标和干物质分配比例,500 mg·L^(-1)烯效唑处理对大葱幼苗控制徒长的效果最好,壮苗指数和根冠比分别较对照提高111.00%和91.30%。