差巴嘎蒿(Artemisia Halodendron)种子萌发对土壤温度、水分和埋深的响应

差巴嘎蒿(Artemisia halodendron)是科尔沁沙地植被的关键种之一,它在沙地植被的恢复演替过程中扮演着重要角色,也被广泛应用于人工固沙活动中。为了了解差巴嘎蒿对风沙环境的适应特点,试验研究了其种子萌发对土壤温度、水分和埋藏深度的响应模式。结果表明:差巴嘎蒿种子在4月和5月的土壤温度条件下萌发良好,总萌发率可达到96%,在7月的土壤温度条件下萌发较差,总萌发率低于50%;若以试验前3天的总萌发率为准,则5月的萌发率远大于其它两个月。在0MPa、-0.1MPa、-0.2MPa、-0.4MPa、-0.8MPa和-1.6MPa水势下,差蒿种子的总萌发率分别为89%、83%、80%、46%、17%和0%。在0.5cm、1.0cm和2.0cm埋深下,最终出苗率分别为90%、32%和9%,当埋深大于4cm后,种子无法出苗。种子萌发对温度、水势和埋深的这种响应模式总体上不利于差巴嘎蒿实生苗在科尔沁沙丘生境中的存活。     

人参核盘菌菌核的菌丝型萌发特性研究

人参核盘菌菌核在自然环境及人工培养条件下很难产生子囊盘,主要通过菌核进行菌丝型萌发侵染寄主。为明确人参核盘菌菌核的菌丝型萌发特性,对人参核盘菌菌核的萌发历程和影响因素进行了研究。结果表明,人参核盘菌菌核吸水性强,前期吸水速度较快,菌核吸水饱和后,是吸水前菌核平均质量的1.99倍。菌核吸水后3 d开始菌丝型萌发,8 d时菌核的菌丝型萌发率到达97.8%,而未吸水的菌核则不能萌发产生菌丝。菌核在干燥的土壤环境中的菌丝型萌发率极低,土壤湿度越大越利于菌丝型萌发。菌核龄越大所需的菌丝型萌发时间越长。15.0～22.5℃为菌核菌丝型萌发的适宜温度。pH为6.0时,其菌核的菌丝型萌发率最高。     

Germination response of Orobanche seeds subjected to conditioning temperature, water potential and growth regulator treatments

Broomrapes (Orobanche spp.) are parasitic weeds that cause significant losses of crop yield. Experiments were conducted to investigate the seed response to the artificial germination stimulant GR₂₄ in three species of Orobanche subjected to preconditioning under various temperatures, water potentials and with plant growth regulators. The highest germination percentages were observed in Orobanche ramosa, Orobanche aegyptiaca and Orobanche minor seeds conditioned at 18°C for 7 days followed by germination stimulation at 18°C. With the increase of the conditioning period (7, 14, 21 and 28 days), the germination percentage of O. ramosa and O. aegyptiaca progressively decreased. When conditioned at −2 MPa, the germination percentage was lower than at 0 and −1 MPa, especially at 13 and 28°C. Orobanche minor seeds could retain relatively high germination if conditioned at 18, 23 or 28°C, even after significantly extended conditioning periods (up to 84 days). GA₃ (30–100 mg L⁻¹), norflurazon and fluridone (10–100 mg L⁻¹), and brassinolide (0.5–1.0 mg L⁻¹) increased seed germination, while 0.01 mg L⁻¹ uniconazole significantly reduced germination rates of all three Orobanche spp. The promotional effects of GA₃ and norflurazon and the inhibitory effect of uniconazole were evident, even when they were treated for 3 days. Germination of Orobanche seeds was much lower when the unconditioned seeds were directly exposed to GR₂₄ at 10⁻⁶ m . This early GR₂₄-induced inhibition was however alleviated or even eliminated by the inclusion of GA₃ or norflurazon (10–50 mg L⁻¹) in the conditioning medium. On the contrary, the inclusion of uniconazole increased the inhibitory effect of GR₂₄, particularly in the case of O. ramosa.     

冬季灌水对土壤中向日葵菌核的活力及其致病力的影响

为明确内蒙古巴彦淖尔市河滩地向日葵菌核病发生轻的原因,在内蒙古农业大学教学农场模拟了巴彦淖尔市河滩向日葵地块的种植条件即对土壤中的向日葵菌核进行了冬季大水漫灌处理,并在次年春天对冬灌水处理后土壤中菌核的活力、草酸分泌量、多聚半乳糖醛酸酶（polygalacturonase,PG）的活性以及致病力进行了测定。结果表明,灌水处理后土壤中菌核萌发率为46%,比未灌水处理的对照降低了27%;草酸分泌量为50.94 μg/mg,PG活性为14.82 U/mg,均显著低于对照。冬灌水处理后的菌核萌发后在离体叶片上接种病斑大小仅为0.69 cm,显著低于未经冬季灌水处理的1.29 cm。2012和2013年的向日葵植株活体接种试验结果表明,用冬灌水处理后的菌核接种后发病株率分别为10.67%和18.37%,显著低于未经灌水但混有菌核的处理。表明冬季灌水处理能够降低土壤中菌核来年对向日葵的致病力,从而降低向日葵菌核病的发病程度。     

不同水分处理下冬小麦冠层温度、叶片水势和水分利用效率的变化及相关关系

小区栽培冬小麦,设计5种程度的干旱胁迫,利用防雨棚分别控制土壤重量含水量为田间持水量的45%、55%、65%、70%、80%,观测不同水分处理下冬小麦冠层温度、叶片水势和水分利用效率的变化及相关关系。结果显示,随着含水量的增加,各处理的平均和最高冠层温度整体呈下降趋势,叶水势和蒸腾速率呈上升趋势,在小麦抽穗期干旱胁迫最严重处理表现出最大水分利用效率,开花期的水分利用效率较抽穗期整体下降了50.70%;相关分析表明,抽穗期小麦的冠层温度与空气饱和差极显著正相关(P<0.01),开花期的冠层温度和叶水势呈显著负相关(P<0.05),冠层温度和空气饱和差存在着极显著正相关,空气饱和差和蒸腾速率极显著负相关,冠层温度和水分利用效率有着显著的正相关性。综上所述,冠层温度在小麦抽穗和开花期完全可以作为作物水分状况的有效监测指标之一。     

环境条件对灰葡萄孢菌菌核萌发的影响

<正>灰葡萄孢菌(Botrytis cinerea)引起的灰霉病可导致植物幼苗猝倒或花朵和果实腐烂,多在冬春季节发生,是保护地蔬菜、水果和花卉生产或储藏过程中一类重要的病原菌。灰霉菌的初侵染主要由菌核或病残体在适宜温湿度时萌发产生的菌丝或孢子侵染植物,关于灰葡萄孢菌的菌丝、分生孢     

Effects of temperature and water limitation on the germination of Stipagrostis ciliata seeds collected from Sidi Bouzid Governorate in Central Tunisia

Most ecological studies in North Africa reveal a process of continuous degradation of rangeland ecosystems as a result of overgrazing. This degradation appears across the decreasing of perennial grass diversity. Indeed, the majority of steppe ecosystems are characterized by a low density of perennial grass species at present. This study evaluated the effects of temperature and water limitation on the seed germination of Stipagrostis ciliata(Desf.) de Winter, a perennial grass species. The seeds were collected from the Bou Hedma Park, Sidi Bouzid Governorate, Central Tunisia. The thermal time and hydrothermal time models were used to describe the seed germination of S. ciliata under different water potentials and temperatures. The germination response of S. ciliata seeds in darkness was evaluated over a range of temperatures(15°C, 20°C, 25°C, 30°C and 35°C) and across a wide range of osmotic potentials(0.0, –0.2, –0.6, –1.2, –1.6 and –2.0 MPa) of the polyethylene glycol(PEG6000) solutions at each temperature level. Among the tested temperatures, 25°C was found to be the optimal temperature to the germination of S. ciliata seeds. The final germination percentage(75.2%) was obtained with distilled water. The progressive decrease of osmotic potential of the PEG6000 solutions inhibited the seed germination. However, the number of days to first germination was increased with a reduction of osmotic potential. A significant positive relationship was identified between final germination percentage of S. ciliata seeds and osmotic potential of the PEG6000 solutions, with R~2 ranging from 0.5678 to 0.8761. Furthermore, a high degree of congruency between predicted and observed germination time course curves was observed. In general, S. ciliata exhibits a significant adaptation capacity for water limitation and high temperature in arid ecosystems.     

Inoculum potential of Sclerotinia sclerotiorum sclerotia depends on isolate and host plant

The soilborne fungus Sclerotinia sclerotiorum infects many important crop plants. Central to the success of this pathogen is the production of sclerotia, which enables survival in soil and constitutes the primary inoculum. This study aimed to determine how crop plant type and S. sclerotiorum isolate impact sclerotial production and germination and hence inoculum potential. Three S. sclerotiorum isolates (L6, L17, L44) were used to inoculate plants of bean, carrot, lettuce, oilseed rape (OSR) and potato, and the number and weight of sclerotia per plant quantified. Carpogenic germination of sclerotia collected from different hosts was also assessed for L6. Production of sclerotia was dependent on both crop plant type and S. sclerotiorum isolate, with OSR and lettuce supporting the greatest number (42–122) and weight (1.6–3.0 g) of sclerotia per plant. The largest sclerotia were produced on OSR (33–66 mg). The three S. sclerotiorum isolates exhibited a consistent pattern of sclerotial production irrespective of crop type; L6 produced large numbers of small sclerotia while L44 produced smaller numbers of large sclerotia, with L17 intermediate between the two. Germination rate and percentage was greatest for larger sclerotia (4.0–6.7 mm) and also varied between host plants. Combining sclerotial production data and typical field crop densities suggested that infected carrot and OSR could produce the greatest number (3944 m^?2) and weight (73 g m^?2) of S. sclerotiorum sclerotia, respectively, suggesting these crops potentially contribute a greater increase in inoculum. This information, once further validated in field trials, could be used to inform future crop rotation decisions.     

Effect of temperature of production of Botrytis allii conidia on their pathogenicity to harvested white onion bulbs

Botrytis allii colonies incubated at low temperatures have been reported to produce larger conidia that germinate faster and give rise to longer germ-tubes than those grown at room temperature. The present study compared the effect of conidia produced at 20°C and at 0 and –2°C on their pathogenicity to artificially inoculated white onion bulbs, and the effect of conidial concentration (5×10³ and 5×10⁴ conidia/mL) on disease incidence, lesion area, incubation and latent period during storage at 20, 5 and 0°C. At all storage temperatures and periods tested conidia produced at −2°C caused a higher disease incidence and larger areas of rot than those produced at higher temperatures. When the conidial production temperature was raised to 20°C, the duration of incubation on the bulbs inoculated with 5×10⁴ conidia/mL was more than doubled during storage at 0°C, tripled at 5°C, and took 50% longer at 20°C. The incubation period was not significantly affected by conidial concentration at 20°C, and only slightly at 5 and 0°C, but at low temperatures the latent period was longer because of the delay induced in sporulation. These data are consistent with the packers' opinion that cross-infection of spring onions by long-term refrigerated onions in grading lines caused earlier and heavier rotting.     

Effects of temperature,vapour pressure deficit and radiation on infectivity of conidia ofBotrytis cinerea and on susceptibility of gerbera petals

The effect of vapour pressure deficit, temperature and radiation on the postharvest susceptibility of gerbera flowers toB. cinerea, on the water relations of gerbera flowers and on the lesion formation after conidial infection ofB. cinerea was studied. The temperature range in whichB. cinerea could germinate and growin vitro is 5–30 °C. In climate chamber experiments flowers had more lesions ofB. cinerea at temperatures of 20 and 25 °C than at 10 and 15°C. At 15, 20 and 25°C the infectivity ofB. cinerea conidia was negatively affected during a storage-period of 7 days. At a vapour pressure deficit (VPD) of 200 Pa significantly more conidia ofB. cinerea were infective than at 800 Pa. At a VPD of 800 Pa the susceptibility of gerbera flowers forB. cinerea was not significantly different than at 200 Pa. High radiation levels in glasshouses in spring and summer negatively influenced the infectivity of conidia ofB. cinerea on the flower surface, but did not affect the susceptibility of gerbera flowers forB. cinerea. In spring and early summer conidia lost their infectivity at high radiation levels, high temperatures and high levels of VPD. In summer gerbera flowers could be more susceptible toB. cinerea because of high temperatures in glasshouses, but the negative effect of radiation on the conidia ofB. cinerea seemed to overrule the temperature effect. Thus, the numbers of lesions in spring and summer can be low compared with the numbers in other seasons, although the numbers ofB. cinerea colonies on spore traps can be high. The effect of temperature on the susceptibility of gerbera flowers can probably be explained by changes of water status in the petals. At higher temperatures the number of lesions and the turgor (=water potential—osmotic potential) in the petals increased. Temperatures <10°C during lesion formation (RH>95% and VPD<50 Pa) had a temporary negative effect on the number of lesions. After 3 days of incubation the numbers of lesions were about equal (30 lesions/cm²) from 5 to 20°C. At 30°C no lesion formation was observed even after 3 days.     

土壤水势对桃树茎干变化的影响研究

本试验主要研究不同土壤水势条件下桃树茎干的变化规律。试验设置4个处理,分别是-100~-110 kPa(A区),自然条件下作为对照(B区),-10~-20 kPa(C区),-40~-60 kPa(D区)。分析不同月份各个处理桃树茎干日变化之间的差异,结果表明,桃树茎干日生长量在休眠期基本为负值,第一生长期内平均日生长量在20~50μm之间,第二生长期内平均日生长量在30~70μm之间,停长期内平均日生长量出现正负交替。结果同时表明,各处理桃树在整个生长周期内茎干生长量存在显著差异,整个生长周期内生长量由大到小顺序为DCAB。综合分析得出,在桃树整个生长周期内将土壤水势维持在-40~-60 kPa时有利于桃树生长。     

不同耕作措施对冬小麦农田土壤水分和温度的影响

在多年田间定位试验的基础上,研究了内陆河绿洲灌区不同耕作措施对冬小麦农田土壤水分和温度的影响.结果表明,冬小麦返青至成熟,0～150 cm土层深度范围内免耕秸秆覆盖处理土壤平均含水量较免耕和传统耕作处理高0.21%和0.23%,免耕对土壤含水量影响不明显;冬小麦收获后,0～150 cm土层深度范围内土壤含水量平均值的高低顺序为:免耕秸秆覆盖＞免耕＞传统耕作.冬小麦返青至成熟期间,无论晴天还是阴天,0～25 cm土层深度范围内免耕秸秆处理土壤温度均低于免耕和传统耕作处理,免耕秸秆覆盖和免耕处理土壤温度平均值较传统耕作分别低2.8℃和2.6℃,免耕秸秆覆盖处理可以稳定土壤温度.相关分析表明,土壤含水量与土壤温度存在显著负相关关系.     

Assessing potential germination period of weeds with base temperatures and base water potentials

Seed germination partly depends on both base temperature (T_b) and base water potential (Ψ_b), which currently are known only for a small number of species. Laboratory experiments were conducted to estimate these parameters for 14 weed species using the ‘x‐intercept’ method. T_b and Ψ_b (°C and MPa) for the 14 weed species were as follows: Amaranthus retroflexus (8.9 and ?0.95), Ambrosia artemisiifolia (3.6 and ?1.28), Avena fatua (2.2 and ?1.02), Capsella bursa‐pastoris (4.5 and ?0.95), Chenopodium album (5.9 and ?0.80), Echinochloa crus‐galli (6.2 and ?1.19), Geranium dissectum (0.6 and ?3.31), Matricaria perforata (2.0 and ?0.75), Picris echioides (5.2 and ?0.79), Polygonum lapathifolium (5.8 and ?1.55), Senecio vulgaris (2.5 and ?1.23), Setaria pumila (8.6 and ?0.75), Solanum nigrum (11.6 and ?0.89) and Veronica hederifolia (0.2 and ?1.67). The two parameters were used to determine potential germination times during expected non‐dormancy periods for three contrasting climatic years in Dijon, France. The number of potential germination days varied little among the tested climatic years, but substantially among species, ranging from 95 ± 9 days for V. hederifolia to 280 ± 7 days for M. perforata. These results may be of value for development of predictive growth models and understanding times when weed control may be most feasible.     

Seed germination of the invasive species Piper aduncum as influenced by high temperature and water stress

Piper aduncum is a common woody weed throughout the tropics and a successful invader in many areas. As this species most often dominates roadsides and forest margins, and these habitats frequently experience extreme changes in temperature and water availability, it is important to understand how the seeds adapt to these stresses. This study investigated the effect of high temperatures and water stress, continuous, periodic or transient, on P. aduncum seed germination before or after imbibition. It was found that P. aduncum seeds exhibited only intermediate tolerance and did not germinate at temperatures above 35°C or water potentials below ?0.6 MPa. However, this species is well adapted to local conditions, with fruit ripening in the rainy season, seed desiccation tolerance to eRH 8%, rapid germination under wet conditions, higher temperature tolerance than the maximum ground temperature, germination of most seeds after 60 h continuous heat treatment or daily periodic heat treatments up to 5 h at 40°C and insensitivity to 12 h heat treatment at 40°C during the whole germination process. The intermediate tolerance to high temperature and water stress of P. aduncum, in combination with local environmental conditions in Xishuangbanna, makes P. aduncum an intermediate invader in this area.     

采用鼓风机吹落花瓣防治草莓果实灰霉病的研究

灰霉病是草莓生产过程中的主要病害,亟需开发实用的草莓灰霉病绿色防控技术,保障草莓持续健康发展。本研究从第一花序盛花期至果实大量成熟,每周使用鼓风机将发育中果实(花托)上残留的衰老花瓣吹落。在第一、二次吹落花瓣前后分别统计每朵花上花瓣数量,计算每朵花平均花瓣数和花瓣吹落效率。49 d后分别调查花瓣吹落处理区与对照区果实灰霉病发病率。结果显示:草莓盛花期花瓣不易脱落,在盛花期一周后使用鼓风机吹落花瓣的效率较高。连续7次使用鼓风机清理后,对照区果实灰霉病平均发病率(8.27%)显著高于处理区(1.52%)。在草莓第一批果实发育期间使用鼓风机吹落衰老花瓣能显著降低果实灰霉病发病率,该方法对果实灰霉病防效为81.56%。     

辽细辛提取物对灰葡萄孢菌的抑制效果

采用生长速率法和孢子萌发法测定了辽细辛根的不同溶剂(石油醚、氯仿、乙酸乙酯、乙醇)粗提取物和精油对引起黄瓜灰霉病的灰葡萄孢菌菌丝生长和孢子萌发的作用。结果表明,细辛不同溶剂提取物和精油对灰葡萄孢菌的菌丝生长和孢子萌发均有一定的抑制作用,且对孢子萌发的抑制效果好于对其菌丝生长的抑制效果;石油醚提取物和精油的抑菌效果较好,对菌丝生长的EC₅₀分别为177.44 mg/L和159.98 mg/L,对孢子萌发的EC₅₀分别为173.23 mg/L和125.29 mg/L;试验还显示细辛所含的主要抑菌活性成分易被极性小的有机溶剂所提取。     

汉防己甲素对5种植物病原真菌的抑制作用及对灰葡萄孢的作用机制初探

为寻找环境友好型的农药先导化合物,利用菌丝生长速率法研究了粉防己中汉防己甲素对常见植物病原真菌的抑制活性,结果表明,汉防己甲素对5种常见植物病原真菌均有抑制作用,对立枯丝核菌的抑制作用最强,EC₅₀为33.49 mg/L;对串珠镰孢和瓜类黑腐球壳菌的EC₅₀分别为41.71 mg/L和43.97 mg/L,抑制活性优于对照植物源药剂蛇床子素;对灰葡萄孢的抑制活性与蛇床子素相当。接种蓝莓离体叶片的试验结果表明,汉防己甲素对蓝莓灰霉病具有治疗和保护作用且作用效果与对照药剂蛇床子素基本相当;激光共聚焦显微镜检测发现汉防己甲素可降低灰葡萄孢菌丝内钙离子浓度,汉防己甲素分别与CaCl₂及钙通道阻滞剂维拉帕米两者相互作用可降低灰葡萄孢对各药剂的敏感性,表明其作用机制与钙离子及钙离子通道有关。本文首次报道汉防己甲素对5种植物病原真菌的抑制作用及其作用机制,为其进一步的开发应用提供理论基础。     

Effects of temperature,relative humidity and age of conidia on the incidence of spotting on gerbera flowers caused by Botrytis cinerea

In recent years, spotting of ray florets of gerbera flowers has become an important problem. This type of small necrotic lesions may occur before, but especially shortly after harvesting the flowers.Botrytis cinerea was easily isolated from such lesions. Inoculation withB. cinerea only gave typical necrotic lesions, when dry conidia were dusted on the flowers with a short period of high rh after inoculation. At 18–25 °C a high rh for at least 5 hours was necessary. Rotting of ray florets and receptacles byB. cinerea occurred when inoculated flowers were kept wet for a few days. Spots consist of one to several necrotic, usually epidermal cells. A single conidium could give rise to a necrotic lesion after germination. Germination of conidia and lesion formation occurred between 4 and 25 °C; at 30 °C, germination and lesion formation did not occur. Between 18 and 25 °C, many lesions became visible within 1 day after inoculation; at 4 °C it took 2 to 3 days before lesions could be seen. If kept dry, conidia ofB. cinerea remained ungerminated on ray florets of gerbera flowers and could be removed from the ray florets. Within 1 day at high rh, germination occurred and lesions were produced. Conidia ofB. cinerea, stored dry, were able to survive much longer than the lifetime of a gerbera flower. Even after storage at room temperature for up to 14 months, some conidia were able to germinate in vitro and on ray florets and induce the formation of lesions. Addition of gerbera pollen diffusate stimulated germination and lesion formation.     

抗药性链霉菌S89的诱变选育及对灰霉病菌的抑制作用

采用紫外线照射与药物培养基驯化相结合的方法选育抗药性链霉菌,筛选出4株对腐霉利有显著抗性的突变株(US-1,US-2,US-3和US-4)。US-1和US-3对灰葡萄孢菌的抑菌能力显著高于亲本菌株,US-2和US-4的抑菌能力显著低于亲本菌株。颉颃活性最强的US-1菌株与腐霉利的协同作用表明,7份菌液和3份药液混用后,对灰葡萄孢菌的抑菌圈直径为21.97mm,对离体番茄灰霉病的防效高达77.68%,显著高于菌株单独使用的抑菌效果。     

Inhibition of Methionine Biosynthesis in Botrytis cinerea by the Anilinopyrimidine Fungicide Pyrimethanil

When mycelium of Botrytis cinerea was treated with low concentrations of the anilinopyrimidine fungicide pyrimethanil the total amount of free amino acids increased. Qualitative variations were also induced: alanine, glutamine, lysine, glycine, histidine, asparagine, arginine, threonine and moreover, α-aminobutyrate and β-alanine were accumulated; cyst(e)ine, valine, leucine and citrulline were reduced. When mycelium of B. cinerea was incubated with Na₂[³⁵S]O₄, pyrimethanil at 1·5 μM induced a decrease of [³⁵S]methionine and simultaneously an increase of [³⁵S]cystathionine. These data indicate that the anilinopyrimidine fungicide pyrimethanil inhibits the biosynthesis of methionine and suggest that the primary target could be the cystathionine β-lyase. © 1997 SCI.