Panel Discussion: Factors in the Success and Failure of Microbial Insecticides

Discussion

Panel Discussion: Factors in the Success and Failure of Microbial Insecticides     

Influence of alginate oligosaccharides on growth, yield and alkaloid production of opium poppy (Papaver somniferum L.)

Opium poppy (Papaver somniferum L.), an important medicinal plant, produces several opiate alkaloids including morphine, thebaine, codeine, papaverine and noscapine. Polysaccharides, such as sodium alginate, have been used in depolymerized form as wonderful promoters of plant growth. The present study has revealed that application of alginate oligosaccharides (AO), obtained from sodium alginate irradiated by Co-60 gamma rays, significantly enhances certain physiological/biochemical parameters as well as the overall growth of opium poppy. The highest dose applied was the most effective in increasing the morphine and codeine contents as well as the overall yield of crude opium per plant.     

Optimizing nitrogen levels combined with gibberellic acid for enhanced yield, photosynthetic attributes, enzyme activities, and artemisinin content of Artemisia annua

Artemisia annua L. is an aromatic-antibacterial herb that destroys malarial parasites, lowers fever, and checks bleeding, and from which the secondary compound of interest is artemisinin. It has become increasingly popular as an effective and safe alternative therapy against malaria, and its derivatives are effective against multidrug resistant Plasmodium falciparum strains. Nitrogen is required by the plants in the largest quantity and is most limiting where biomass production is desired. On the other hand, gibberellic acid plays an important role in flowering, growth, and development and also in other physiological and biochemical processes. The feasibility of foliar GA₃ (75 mg·L⁻¹) alone or with varying levels of soil applied nitrogen (40, 80, and 120 mg·kg⁻¹ soil) was tested on A. annua in the present study. The application of GA₃ proved effective in alleviating the growth, photosynthesis, and enzyme activities of A. annua. However, N levels combined with GA₃ showed better responses, and further improvement in these parameters was observed. Furthermore, the most important task we were interested in was to increase the artemisinin content and its yield on a per plant basis. The N combination (80 mg·kg⁻¹ soil) together with GA₃ augmented the content (21.8% more) and yield (55.8% more); this is true for both the treated plants, which were more than the control.     

Screening of mungbean germplasm against mungbean yellow mosaic India virus and its vector Bemisia tabaci

Yellow mosaic disease (YMD) caused by whitefly (Bemisia tabaci) transmitted mungbean yellow mosaic India virus (MYMIV) is an important constraint of mungbean in Pakistan. One hundred sixty-two mungbean genotypes from eight different geographic regions were evaluated for resistance to MYMIV and its whitefly vector B. tabaci. Resistance levels were assessed by visual scoring of symptoms in the field under natural conditions, in net-house by artificial transmission through whitefly and in greenhouse using graft inoculation for two consecutive years in 2008 and 2009. None of the tested genotypes was found to be disease free, while considerable variation in responses was observed among the genotypes and testing methods. All genotypes were found to be systemically infected in the field. In 2008, 32 genotypes were found to be resistant and 67 were moderately resistant with severity index (SI) values ranging from 1.0 to 1.4 and from 1.5 to 2.4, respectively. In 2009 34 genotypes were found to be resistant and 38 were moderately resistant with the same SI value ranges as in 2008, and the remaining genotypes were moderately susceptible to highly susceptible. However, only 35 genotypes were found to be moderately resistant with SI values of 1.5-2.4 and latent periods (LP) of 17-21 days when evaluated using artificial transmission through whiteflies. Similar results were obtained when these genotypes were evaluated using graft inoculation. Significant differences in adult whitefly densities among tested genotypes were also observed during both years but no correlation between the number of whiteflies and disease severity was observed. The results indicated that these genotypes did not have a high level of resistance against MYMIV, however, they may provide sources of partial resistance which can be exploited in the breeding programmes to develop mungbean genotypes resistant to MYMD or they can be used directly as varieties to manage MYMD after evaluation for acceptable agronomic characteristics, adaptation and stability in various regions.     

Sorption and Desorption Behavior of FTuoroquinolone Antibiotics in an Agricultural Soil

<正>Dear Editor,Fluoroquinolones(e.g.,ciprofloxacin(CIP),enrofloxacin(ENR),and levofloxacin(LEV))are an extensively used family of antibiotics prescribed for various infections;however,they are also increasingly used     

Resistance to Peach-potato Aphid,Myzus persicae Sulzer (Hemiptera: Aphididae) in Potato Cultivars

Previous research suggests that potato cultivars offer little aphid resistance. However, few studies have measured the effects of host cultivar on aphid age dependent life table statistics or related these measures to field performance. In this study, laboratory and field studies assessed four commercial potato cultivars (Anya, Desiree, Pink Fir Apple, Santé) for resistance to Myzuspersicae. Cultivars were found to show considerable differences in resistance. In the laboratory, the intrinsic rate of increase (r_m) and effective fecundity of M. persicae was lowest on cv. Anya and highest on cv. Desiree. Aphids also took longer to develop to adults and were smaller in size on Anya compared with Desiree. Field studies over two seasons found that M. Persicae infestations started earlier on Desiree than on Anya and that the greatest weekly counts were recorded on the former.     

Growth,physiology, and biochemical activities of plant responses with foliar potassium application under drought stress – a review

Drought stress affects plant growth and ultimately yield is reduced. Potassium (K) is an essential macronutrient that is required to increase the growth and yield under drought. K plays an important role in osmotic adjustment, opening and closing of stomata, and enzymes activation. K is the component of plant structure that optimizes many physiological as well biochemical processes and ultimately improves the plant growth and yield. This review mainly covers the following topics: impact of drought on plant growth, physiological and biochemical characteristics, the role of K in plant growth, and physiology under drought stress. K is also responsible for enhancing the growth as well as yield attributes of crops under drought stress conditions by altering the physiological and biochemical process.     

仿鼹鼠足趾排列的旋耕-秸秆粉碎锯齿刀片设计与试验

随着保护性耕作的不断发展,实际作业中对旋耕刀性能要求愈发严格,该文在国标旋耕刀基础上,将正、侧切削刃上设计成锯齿状,然后考察实际作业过程中功耗、受力以及作业质量,检测仿鼹鼠足趾排列的旋耕-秸秆粉碎锯齿刀片的田间作业功耗和作业质量。针对该锯齿刀片和国标旋耕刀片在有秸秆颗粒和无秸秆颗粒下进行仿真分析,对比可知:在有秸秆颗粒下,由于刀具要与秸秆接触并发生挤压和剪切作用,从而导致受力以及扭矩值较大。结合理论分析,利用扭矩传感器对仿生锯齿刀和国标旋耕刀进行田间试验。根据0.5 m×0.5 m地表设置不同质量秸秆,分别为0、0.375和0.75 kg(0%、50%、100%),测定拖拉机输出扭矩以及功耗,并依照国标测试方法测定作业质量。田间试验得到扭矩与仿真变化趋势一致。当地表无秸秆和地表含50%秸秆时,锯齿刀片扭矩分别为404.05和438.33 N·m;国标旋耕刀片上扭矩分别为389.27和443.79 N·m。当地表秸秆质量分数为100%时,锯齿刀和国标旋耕刀片上扭矩分别为557.92和507.34 N·m。耕作后地表秸秆和土壤评价结果显示:不同质量含量秸秆覆盖下,仿生锯齿刀耕作后的秸秆掩埋率、土壤破碎率、长度≤15 cm秸秆比例等方面都优于国标旋耕刀。田间试验和仿真结果都显示当地表覆盖秸秆量为0%和100%时,仿生锯齿刀的扭矩高于国标旋耕刀。虽然仿生锯齿刀只在秸秆覆盖量为50%时扭矩与功耗优于国标旋耕刀,但在3种秸秆覆盖量下仿生锯齿刀的耕后地表质量都明显优于国标旋耕刀。综上考虑,在实际作业中,可适当收集田间秸秆。该研究为实现只应用一种刀片来完成旋耕和秸秆粉碎2种不同作业目标提供了参考。     

The effect of phosphorus addition,soil moisture,and plant type on soil nematode abundance and community composition

Journal of Soils and Sediments - Environmental variables such as soil moisture and phosphorus (P) might influence above- and below-ground biodiversity. In this study, we investigated the rarely...     

PGPRs of plum (Prunus domestica) rhizosphere enhance plant growth and antagonise fungal activity in vitro

Plant growth promoting rhizobacteria (PGPR) promote the plant growth by various direct and indirect mechanisms. The present study was undertaken to isolate and characterise the PGPRs of plum (Prunus domestica) rhizosphere in Pakistan. A total of 95 rhizobacteria were isolated, out of which 40 strains were selected on the basis of morphological, biochemical and Gram staining characteristics. The selected isolates were screened for in vitro plant growth promoting potential and were subsequently evaluated for host plant growth promotion. The selected isolates demonstrated strong lytic enzymatic activities and were able to produce ammonia, siderophore, Hydrogen cyanide along with capability of phosphate solubilisation. Moreover, the results showed a significant growth suppression of pathogenic Fusarium oxysporum and Rhizoctonia solani in an in vitro assay. The plant microbe interaction study was carried out using 11 most efficient rhizobacterial strains inoculated to roots of plum plants. The inoculated PGPRs significantly augmented the leaves number per shoot, shoot diameter, shoot length and plant height. The inoculation also significantly increased the chlorophyll contents of leaves, concentration of micro and macro nutrients compared with control. The current study shows the importance of these selected PGPRs as bio-fertilizer to improve the health and productivity of plum species in Pakistan.