Interactive Effects of Mycorrhization and Fertilization on Growth,Nutrition, and Water Relations of Sweet Birch

Abstract

Pisolithus tinctorius(Pers.) Coker & Couch was evaluated as an ectomycorrhizal associate of sweet birch (Betula lentaL.). Sand culture and mine soil growth media were employed, and three fertilization treatments were imposed by application of differing Hoagland's nutrient solution #2 concentrations. The high fertilization treatment suppressed mycorrhizal formation by P. tinctoriusin both growth media, while the medium rather than the low treatment induced the most extensive colonization by this mycobiont. Seedlings with induced P. tinctoriusmycorrhization exhibited enhanced above— and below-ground growth according to shoot dimensions and dry weight and root weight and length. However, these responses were frequently absent with high fertilization, especially in the mine soil. Inoculated seedlings had higher foliar N, P, and K concentrations overall but lower Ca, Mg, and S concentrations than uninoculated seedlings. Those with P. tinctoriusalso had lower concentrations of several potentially phytotoxic trace elements, specifically Zn, B, Mo, and Al. Furthermore, xylem pressure and soil water potentials measured during a simulated drought episode indicated that water uptake was enhanced by these mycorrhizae. Again, however, the above physiological responses were often compromised by high fertilization. Collectively, these results indicate that P. tinctoriusis a viable mycobiont for the inoculation of sweet birch, and when substrate fertility is not excessive, can avail this host of physiological benefits that result in substantial growth enhancement.     

熊蜂对油茶授粉结实的影响初探

油茶为异花授粉植物,其产量与传粉昆虫关系密切,但油茶昆虫授粉问题一直未能得到有效解决,而熊蜂在温室大棚作物授粉方面具有效益高、品质好等优点.本文以普通油茶为研究对象,通过引进熊蜂对其进行授粉试验,分析熊蜂对油茶授粉结实的影响,以期为油茶的引蜂授粉研究和应用提供参考.试验结果表明,熊蜂的不同投放方式对油茶的座果结实有很大影响,熊蜂的自由式授粉、限制性授粉和自然昆虫授粉的座果率分别为36.78%、0.22%和18.23%,自由式授粉能显著提高油茶产量,而高饱和密度的限制性熊蜂释放方式反而会有减产作用;另外通过熊蜂授粉试验发现油茶不同亲本间的组配授粉结实率差异很大.因此在合理控制的情况下熊蜂能有效提升油茶产量.     

5种设施常用农药对欧洲熊蜂的毒力及残毒测定

为了合理保护和利用欧洲熊蜂,测定了5种设施常用药剂对欧洲熊蜂的毒力及残毒毒性,结果表明:噻虫嗪对欧洲熊蜂的半致死量LD50值为0.061μg/蜂,为高毒;氯虫苯甲酰胺对其半致死量LD50值为8.507μg/蜂,为中毒;藜芦碱、印楝素和苯醚甲环锉对其半致死量LD50值分别为69.936μg/蜂、109.141μg/蜂和336.094μg/蜂,均为低毒,其中苯醚甲环锉的毒性最低。残毒试验结果表明:天然植物源农药藜芦碱、印楝素对熊蜂没有残留毒性;杀菌剂苯醚甲环锉对其有轻微毒性;杀虫剂噻虫嗪、氯虫苯甲酰胺对其毒害比较明显,其中噻虫嗪在喷药5d后仍有轻微毒性。     

Compatibility of traditional and novel acaricides with bumblebees (Bombus terrestris): a first laboratory assessment of toxicity and sublethal effects

BACKGROUND: This project assessed the potential hazards of different classical and novel acaricides against an important non‐target and beneficial insect for the pollination of wild flowers and cultivated crops, the bumblebee Bombus terrestris (L). Twenty‐three acaricides used commercially in the control of phytophagous mites (Acari) were tested in greenhouses and/or the open field. Side effects included acute mortality and also sublethal effects on nest reproduction. The different compounds were administered in the laboratory via three different worst‐case field scenario routes of exposure: dermal contact and orally via the drinking of treated sugar water and via treated pollen. The compounds were tested at their respective maximum field recommended concentration (MFRC), and, when strong lethal effects were observed, a dose–response assay with a dilution series of the MFRC was undertaken to calculate LC₅₀ values. RESULTS: From the different acaricide classes, several chemistries caused high levels of acute toxicity in bumblebee workers, especially bifenthrin and abamectin which resulted in 100% mortality by contact. In addition, several acaricides tested were found to have a detrimental effect on drone production. For oral exposures via treated sugar water, the dose–response assay showed the LC₅₀ values for abamectin, bifenazate, bifenthrin and etoxazole to be 1/15 MFRC (1.17 mg AI L^?1), 1/10 MFRC (9.6 mg AI L^?1), 1/83 MFRC (0.36 mg AI L^?1) and 1/13 MFRC (4.4 mg AI L^?1) respectively, indicating that their use should be carefully evaluated. CONCLUSION: Overall, the results suggest that most of the acaricides tested are compatible with bumblebees, with the exceptions of abamectin, bifenazate, bifenthrin and etoxazole. However, the risks also depended on the type of treatment. As a result, the sugar water treatment seems to present the worst‐case situation of exposure, indicating that this approach is suitable for determining the hazards of pesticides against bumblebees. Finally, it is suggested that future tier testing under more field‐related conditions is required for a final decision of their risks. Copyright © 2010 Society of Chemical Industry     

地熊蜂为重庆温室茄子授粉的效果研究

为了有效利用熊蜂授粉,在重庆地区开展了熊蜂为温室茄子授粉效果的研究。结果表明,与自然授粉（CK）相比,熊蜂授粉组的茄子坐果率提高了46.30%,畸形果率下降了70%,单果质量增加了37.45%,株产量增加了68.28%,VC含量增加了22.69%,总糖含量降低了7.27%。应用地熊蜂为重庆地区温室茄子授粉,不仅可以促进坐果率,提高产量,而且还可以改善果实品质。     

蒺藜总黄酮和总皂苷提取工艺的优化

以中药蒺藜的总黄酮和总皂苷含量为筛选指标,分别对索氏提取法、微波辅助提取法、超声波提取法设计正交试验,比较3种方法对蒺藜有效成分的提取效率.每种提取方法均分别得到总黄酮、总皂苷的优化方案以及兼顾两者含量的整合方案,最后进行得率比较,优选最佳提取工艺.结果发现微波法对总皂苷的提取得率最高,对总黄酮的提取效率也达到了最高得率的76.3%,单次提取即可同时达到2种物质的最优化,是可以同时兼顾2种物质提取率的较好方法.其最佳提取条件为70%乙醇,液料比为30,静置20 min后提取50 min.该方法简便、提取效率高,可用于蒺藜原料的质量监测与控制.     

Indirect effects of earthworms on microbial assimilation of labile carbon

Interactions between earthworms and microorganisms can be important in regulating the rate of soil carbon turnover and maintaining soil fertility in agroecosystems. Despite the significance of earthworms in nutrient cycling in agroecosystems, the indirect influence of earthworms on C assimilation by microorganisms has not been adequately quantified. We assessed microbial assimilation of ¹³C-labeled acetate in earthworm (Lumbricus terrestris) middens and surrounding soil collected from maize agroecosystems. Incorporation of ¹³C into microbial lipids was used as an indicator of microbial growth rates. Earthworm middens had significantly lower concentrations of microbial phospholipid phosphates and lower natural abundance δ¹³C than the surrounding soil. After incubation with ¹³C-labeled acetate, microbial communities in earthworm middens had greater ¹³C/¹²C ratios of microbial lipids than microbial communities from surrounding soil. The ¹³C enrichment per unit of microbial phospholipid was much greater in middens than in surrounding soil indicating that: (i) microbial lipid synthesis was significantly higher in the earthworm middens; (ii) microbial assimilation efficiency for ¹³C-labeled acetate was greater in midden soil; or (iii) assimilation of ¹³C-labeled acetate relative to other C sources was proportionately greater in middens than in the surrounding soil. Our results suggest that there were functional differences between microbial communities in earthworm middens and surrounding soil, probably due to a combination of physical, chemical, and biological changes in the midden microenvironment. The resulting differences in microbial communities or activity increased microbial growth rates and assimilation of readily available C substrates in middens relative to surrounding soil.     

熊蜂为温室番茄授粉的效果研究

为了有效利用熊蜂授粉,在重庆地区开展了熊蜂为温室番茄授粉效果的研究。结果表明：与对照组相比,熊蜂授粉组的番茄坐果率提高了35.94%,畸形果率下降了65.78%,单果重量增加了22.31%,株产量增加了29.88%,Vc含量增加了13.32%。     

Bombus terrestris as pollinator‐and‐vector to suppress Botrytis cinerea in greenhouse strawberry

BACKGROUND: Bombus terrestris L. bumblebees are widely used as commercial pollinators, but they might also be of help in the battle against economically important crop diseases. This alternative control strategy is referred to as pollinator‐and‐vector technology. The present study was designed to investigate the capacity of B. terrestris to fulfil this role in greenhouse strawberry flowers, which were manually inoculated with a major plant pathogen, the grey mould Botrytis cinerea Pers.: Fr. A model microbiological control agent (MCA) product Prestop‐Mix was loaded in a newly developed two‐way bumblebee dispenser, and, in addition, the use of the diluent Maizena‐Plus (corn starch) was tested. RESULTS: Importantly, loading of the MCA caused no adverse effects on bumblebee workers, with no loss of survival or impairment of flight activity of the workers during the 4 week flowering period. Secondly, vectoring of Prestop‐Mix by bumblebees resulted in a higher crop production, as 71% of the flowers developed into healthy red strawberries at picking (preharvest yield) as compared with 54% in the controls. In addition, these strawberries were better protected, as 79% of the picked berries remained free of B. cinerea after a 2 day incubation (post‐harvest yield), while this percentage was only 43% in the control. Overall, the total yield (preharvest × post‐harvest) was 2–2.5 times higher than the total yield in the controls (24%) in plants exposed to bumblebees vectoring Prestop‐Mix. Thirdly, the addition of the diluent Maizena‐Plus to Prestop‐Mix at 1:1 (w/w) resulted in a similar yield to that of Prestop‐Mix used alone, and in no negative effects on the bumblebees, flowers and berries. CONCLUSIONS: This greenhouse study provides strong evidence that B. terrestris bumblebees can vector a MCA to reduce B. cinerea incidence in greenhouse strawberries, resulting in higher yields. Similar yields obtained in the treatments with Prestop‐Mix and Prestop‐Mix + Maizena‐Plus suggest an equally efficient dissemination of the biocontrol agent into the flowers with only half the initial concentration of Prestop‐Mix, which illustrates the importance of the diluent. Copyright © 2011 Society of Chemical Industry     

蒺藜生长发育动态研究

采用人工栽培方法,对蒺藜生长发育规律进行了研究。结果表明:不同发育时期蒺藜各条茎的生长量均严格受到萌发次序的制约,二者之间存在直线或二次函数关系。茎生长最快时期为7月25日至8月10日,日生长量为7.141 cm/d。单株叶片数累积高峰出现在8月10日;全株生物量累积表现为“慢—快—慢”增长。整个生育期内共发生2次生长中心的转移,可作为生产上水肥调控的重要依据。