一串红种子黏液对其基本性状及萌发的影响

【目的】研究种子黏液对一串红种子基本性状和萌发的影响,为一串红种苗生产提供支持。【方法】以一串红‘奥运圣火’有黏液和无黏液种子为材料,研究了黏液对种子基本物理性状、吸水和失水特性、粘土能力、萌发特性和植株主要观赏性状的影响。【结果】吸水后,一串红有黏液种子的平均长度、宽度、厚度和质量均显著增大,而无黏液种子仅平均长度和宽度显著增大。黏液可以增强一串红种子的粘土能力,粘土后有黏液干种子的平均质量是无黏液干种子的9.3倍。与无黏液种子相比,黏液可以促进一串红种子吸收大量水分,减缓种子水分散失。黏液种子在吸水100min时可以达到饱和状态,吸收的水分是自身质量的6.81倍,在室温条件下经过36h脱水才能达到质量恒定;无黏液种子在吸水60min时可达到饱和状态,吸收的水分是自身质量的0.59倍,经3h脱水即可达到质量恒定。一串红有黏液种子发芽势、发芽率、发芽指数、活力指数、根长、苗长均显著高于无黏液种子,发芽持续时间显著短于无黏液种子。种子黏液对一串红主要观赏性状无显著影响。【结论】黏液对一串红种子萌发特性有明显影响,有利于一串红种子的萌发和成苗。     

水稻根际促生菌的筛选鉴定及促生能力分析

植物根际促生菌（Plant growth-promoting rhizobacteria,PGPR）可分泌植物生长激素,促进土壤养分循环,是生物肥料重要的种质资源。本文从水稻根际土壤分离纯化根际促生菌,进行菌株鉴定,测定其促生能力。经过16S rDNA测序比对,筛选得到解磷菌4株（Bacillus pumilus LZP02,Bacillus aryabhattai LZP08,Staphylococcus epidermidis LZP10,Bacillus ginsengisoli LZP05）,溶磷菌3株（Bacillus megaterium LZP03,Bacillus oryzaecorticis LZP04,Bacillus ginsengisoli LZP07）,解钾菌3株（Bacillus aryabhattai LZP01,Bacillus subtilis LZP06,Bacillus licheniformis LZP09）。养分转化能力测试结果表明,Bacillus aryabhattai LZP01和Bacillus subtilis LZP06解钾能力较好;Bacillus pumilus LZP02和Bacillus huizhouensis LZP05解磷能力较强;Bacillus megaterium LZP03和Bacillusginsengisoli LZP07溶磷能力较好。对养分转化能力较强的菌株进行激素分泌能力测定,结果表明6种菌株均能产生生长素、赤霉素,均具有合成铁载体的能力。综合分析菌株养分转化与激素分泌能力发现,Bacillus megaterium LZP03、Bacillus huizhouensis LZP05和Bacillus subtilis LZP06促生能力较强,具有较强的开发利用潜力。研究成果为水稻微生物肥料的开发与生产提供了理论和技术支持。     

一株溶磷菌对盐地碱蓬修复盐渍土Cd污染的促进效应

为提高盐渍土Cd污染植物修复效率,探讨溶磷菌对盐地碱蓬生长和镉提取效果的影响,采用浸根法收集水培(含2%NaCl)盐地碱蓬的根系分泌物,将其作为唯一碳源培养5株具有Cd活化能力的溶磷菌并依据细菌OD值绘制生长曲线。挑选繁殖速度较快且溶磷和活化Cd能力显著性强(P0.05)的大肠埃希菌(Escherichia)在3个NaCl浓度(0.3、6、12 g·L~(-1))处理下,采用摇瓶实验研究该条件下大肠埃希菌对Ca_3(PO_4)_2和CdCO_3的溶解效应及代谢产物变化。进一步采用Cd平均含量为1.37 mg·kg~(-1)的污灌菜园土,在3个外源NaCl浓度(0、4、8 g·kg~(-1))处理下,利用盆栽实验研究大肠埃希菌对盐地碱蓬修复盐渍土Cd污染的促进效应。结果显示:随盐分增加(0.3、6、12 g·L~(-1)),菌株平均绝对溶磷量(扣除不接菌对照值)分别为80.19、78.79、77.54 mg·L~(-1),平均绝对活化Cd量依次为17.84、17.30、19.73 mg·L~(-1),说明盐分的增加没有阻碍菌株的溶磷功能,且随盐分的增强,可促进Cd的活化。不同盐分下菌株的代谢物组成有明显变化,0.3、6、12 g·L~(-1)盐分处理下菌株分泌的有机酸分别为5、10、13种,分泌的氨基酸分别为4、8、8种。其中缬氨酸的量随盐分增加显著增加(P0.05)。盆栽实验中,4 g·kg~(-1)盐分胁迫下,接菌处理的生物量和根际土壤溶液Cd含量较不接菌对照显著增加(P0.05),Cd总活化量平均增加3.17倍,全量和DTPA提取态Cd富集系数平均提高260%。综上,盐分胁迫下大肠埃希菌可正常生长并促进盐地碱蓬Cd富集。     

超旱生常绿灌木沙冬青的组织培养技术研究

沙冬青是濒危的第三纪孑遗植物,也是中国北方干旱半荒漠地区惟一的常绿阔叶灌木,具有很好的抗逆基因资源。为了探索在不影响沙冬青正常生长的情况下,开展其组织培养技术研究,首先将消毒的沙冬青种子在含有1/2MS固体培养基的培养皿中发芽和培育无菌苗;然后将无菌苗部分侧根附着在培养基表面,发现培养基表面生长的侧根能被诱导形成大量带有根毛的短侧根;相比传统的外植体组织培养技术,主要利用毛状侧根作为幼嫩外植体,结果在CDB1(MS 1.0 mg/L 2,4-D 0.1 mg/L 6-BA,pH 5.8)培养基上能诱导愈伤组织形成,并在CDB6（MS 0.2 mg/L IBA 0.1 mg/L KT 0.5 mg/L GA3,pH 5.8)培养基上能对愈伤组织进行继代与扩繁。与此同时,研究发现沙冬青具有腋芽生长特性,以及沙冬青幼苗在RA(1/2MS 0.5 mg/L IBA,pH 5.8)培养基可以诱导大量不定根的形成。以上研究发现将有利于在保护沙冬青有限种质资源的前提下,开展沙冬青的无性繁殖和组织培养研究,以及沙冬青种质保护与生态应用。     

棉隆与生物有机肥协同防治芹菜根腐病及其对根际土壤微生物数量的影响

本研究测定土壤消毒剂棉隆熏蒸与生物有机肥协同处理芹菜根腐病高发的芹菜地后,对芹菜根腐病的防治效果及根际土壤微生物变化的影响。结果表明,未经过土壤处理的芹菜地栽培60d后,芹菜根腐病发病率为29.03%,经过棉隆和生物菌肥协同处理后,对芹菜根腐病防效高达95.14%。土壤处理后不同时间采样测定发现土壤真菌、细菌的种类和数量显著低于未处理土壤,随着定植时间的延长土壤微生物得到复壮,微生物群落数量和未处理土壤相近。因此,说明棉隆对芹菜根腐病具有显著的防治效果,与生物有机肥协同应用,可以维持土壤微生物结构,对土传病害的可持续控制具有重要的意义。     

2种草本植物根系对崩岗洪积扇土壤分离的影响

为探讨草本植物根系对崩岗洪积扇土壤分离的影响,以宽叶雀稗(Paspalum wettsteinii)和巨菌草(Pennisetumsp.)为研究对象,采用变坡水槽冲刷试验,研究种植草本植物后土壤分离的变化特征及影响因素。结果表明:各土层平均土壤分离速率大小为裸地(69.93g/(s·m2))宽叶雀稗(57.42g/(s·m2))巨菌草(43.28g/(s·m2)),且不同植被土壤分离速率均随着土层的加深呈幂函数增加;根长密度是影响土壤分离最重要的根系指标,宽叶雀稗小区土壤分离速率随各根系参数指标的增大呈对数函数下降,而巨菌草区则表现为幂函数下降,体现了不同植被根系构型对土壤分离效应的差异;2种草地土壤分离速率可以用水流剪切力、土壤抗剪强度和根长密度很好的模拟(NSE≥0.90)。研究结果可为崩岗治理措施的配置提供科学依据。     

Root development of winter wheat in erosion‐affected soils depending on the position in a hummocky ground moraine soil landscape

Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g^?1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity.     

Timely supplemental irrigation changed nitrogen use of wheat by regulating root vertical distribution

Crop nitrogen (N) uptake depends on the root absorption area and the soil N availability which are closely related to the soil water status. With the increasing water shortages in the North China Plain, supplemental irrigation (SI) to winter wheat is a promising technique. To clarify the relationships between water and nitrogen use, four SI regimes in Tritcum aestivum L. cv. Jimai 22 were set up: no‐irrigation after emergence (T1), SI at jointing and anthesis (T2), SI at sowing, jointing and anthesis (T3), and SI at pre‐wintering, jointing and anthesis (T4). The results indicate that T2 had higher root length density (RLD) and root surface area density (RAD) in the 0–20, 60–80, and 80–100 cm soil layers, as well as higher post‐anthesis N uptake from soil by 23–26% in 2012–2013 and 162–177% in 2013–2014, compared to T3 and T4. The grain yield under T2 was lower than T3 but was not significantly different from T4, whereas its water use efficiency (WUE) was higher relative to both T3 and T4. There were no significant differences among T2, T3, and T4 in N use efficiency (NUE). The N uptake after jointing and WUE were positively correlated with the RLD and RAD in the 0–20 cm soil layer. The NUE was positively correlated with the RLD and RAD in the 20–40 cm soil layer. These results indicate that timely SI at jointing and anthesis was dependent on a suitable water supply at sowing, which increased the soil water content in the upper soil layer after jointing and improved the absorption area of the roots in both the deep and surface soil layers; this further improved the post‐anthesis N uptake from the soil and the WUE. This approach can be a valuable way to maintain high grain yields and NUE in winter wheat while using less irrigation and achieving higher WUE in the North China Plain.     

Yield and nitrogen use efficiency of wheat increased with root length and biomass due to nitrogen,phosphorus, and potassium interactions

Balanced applications of nitrogen (N), phosphorus (P), and potassium (K) are known to increase grain yield of wheat but the impact of the interactions among N, P, and K on root growth and nitrogen use efficiency (NUE) have not been proven. The aim of this study was to investigate the effect of balanced applications of N, P, and K on the rooting patterns and NUE of wheat. Two glasshouse experiments were conducted. A rhizobox study was used to assess the impact of interactions among N, P, and K fertilisers on total root length, biomass, specific root length, root length density, N use efficiency (NUE), and N uptake efficiency of the shoots (NUpE_shoot) and N nutrition index. In a separate pot study, plants were grown to maturity to confirm the effect of the observed changes in root growth on NUE, NUpE_grain, and grain/biomass yield. In the rhizobox experiment when plants were supplied with N+P+K, total root biomass increased approximately six‐fold relative to plants grown with N alone or with no fertiliser. Plants exposed to N+P+K had NUpE_shoot and NUE values that were five and ten times higher, respectively, than plants that received just fertiliser N. Plants supplied with N+P or N+P+K had N nutrition indices close to one (N‐adequate), while plants that only received N had an index of 0.62 (N‐deficient). The pot study confirmed that the changes in root length and biomass in plants exposed to N+P+K resulted in significant increases in NUE, NUpE_grain, shoot biomass, and grain yield at maturity. Interactions among fertiliser N, P, and K played a critical role in influencing root biomass and length, which was associated with increases in NUE, NUpE_shoot and NUpE_grain.     

四川豇豆根腐病菌对咪鲜胺敏感基线的建立

为评价四川豇豆根腐病菌对咪鲜胺的抗药性水平,科学使用咪鲜胺可持续防治豇豆根腐病,采用菌丝生长速率法,测定63株四川省豇豆根腐病菌对咪鲜胺的毒力曲线,建立敏感基线,评价其潜在的抗性风险。参试菌株的敏感性频率分布呈连续的单峰曲线,接近正态分布,平均值为EC50 值0.0063±0.0028 mg/L,这个值可用来监测豇豆根腐病原菌种群对咪鲜胺的敏感性变化。参试菌株中,61.9%为敏感菌株,38.1%为低抗药性菌株,没有出现高抗药性和中抗药性菌株。因此,只要加强田间抗药性监测,在四川豇豆生产上咪鲜胺仍可作为防治豇豆根腐病的有效药剂使用。