Virus transmission by aphids in potato crops

This paper reviews the contribution of vector activity and plant age to virus spread in potato crops. Determining which aphid species are vectors is particularly important for timing haulm destruction to minimize tuber infection by potato virus Y (PVY). Alate aphids of more than 30 species transmit PVY, and aphids such asRhopalosiphum padi, that migrate in large numbers before flights of the more efficient vector,Myzus persicae, appear to be important vectors. Differences in methodology, aphid biotypes and virus strains prevent direct comparisons between estimates of vector efficiencies obtained for aphids in different countries in north western Europe. M. persicae is also the most efficient vector of potato leafroll virus (PLRV), but some clones ofMacrosiphum euphorbiae transmit PLRV efficiently toNicotiana clevelandii and potato test plants. The removal of infected plants early in the season prevents the spread of PLRV in cool regions with limited vector activity. The proportion of aphids acquiring PLRV from infected potato plants decreases with plant age, and healthy potato plants are more resistant to infection later in the season. Severe symptoms of secondary leafroll developed on progeny plants of cv. Maris Piper derived from mother plants inoculated with PLRV in June or July of the previous year. Progeny plants derived from mother plants inoculated in August showed only mild symptoms, but the concentration of PLRV in these plants was as high as that in the plants with severe symptoms.     

假蒟提取物对感染柔嫩艾美耳球虫鸡血液指标的影响

本试验旨在研究假蒟提取物对感染柔嫩艾美耳球虫鸡血液指标的影响。270只1日龄海南文昌公鸡,随机分为6个组,每组3个重复,每重复15只,T1、T2和T3组为对照组(依次分为不感染不给药组、感染不给药组、感染给药组);T4、T5和T6组为假蒟添加组,分别在基础日粮中添加200、400、600mg/kg假蒟提取物粉剂。15日龄时,每组随机抽取30只鸡,除T1组灌服生理盐水外,其他各组鸡均经口接种柔嫩艾美耳球虫卵囊悬液,分别于接种前1d,接种后3、6、9d清晨采血测定其血液指标。结果表明,与感染球虫不给药的T2组相比,假蒟组(T4、T5、T6)可以显著降低感染球虫鸡粪便中球虫卵囊值(P0.05)。假蒟组在感染球虫后第6天,与T1组比,RBC、HGB、HCT、Ca2+、Na+、Cl-、TP、ALB、GLB、TG、CHOL、T4等指标呈下降趋势;但在感染球虫后第9天,TP、GLB含量均显著高于T1组(P0.05);在感染球虫后第6天,假蒟组与对照组相比,ALT、AST浓度水平均显著降低(P0.05)。结果提示,假蒟提取物能提高感染球虫后鸡机体免疫机能,降低肝脏损伤,降低鸡感染球虫后粪便卵囊值,具有一定的抗球虫效果。     

Biological activity of the essential oil from the leaves of Piper sarmentosum Roxb. (Piperaceae) and its chemical constituents on Brontispa longissima (Gestro) (Coleoptera: Hispidae)

The results showed that the essential oil from Piper sarmentosum has strong antifeedant and toxicity effects on Brontispa longissima. The best antifeedant and contact toxicity effects were observed in the 1st-2nd instar larvae. The essential oil also displayed a notable fumigation effect on the eggs and pupae of B. longissima. It took the control-treated insects 43.34 d to complete one generation, while the insects treated with 2000 mg/L essential oil needed 73.58 d. The essential oil was analyzed by gas chromatography/mass spectrometry and 41 components were identified. Myristicin (65.22%) and trans-caryophyllene (13.89%) were the major components. Myristicin exhibited strong antifeedant and contact toxicity effects on both the 3rd instar larvae and the imagoes of B. longissima, when it showed a significant fumigation effect on the eggs and pupae of B. longissima. Another P. sarmentosum essential oil and myristicin all showed a strong inhibiting effect on the growth and development of B. longissima along with the activity of AChE, CarE, GSTs and Na⁺, K⁺-ATPase in B. longissima larvae.     

Nutrient stocks of short-term fallows on a high base status soil in the humid tropics of Papua New Guinea

In order to understand nutrient dynamics in tropical farming systems with fallows, it is necessary to assess changes in nutrient stocks in plants, litter and soils. Nutrient stocks (soil, above ground biomass, litter) were assessed of one-year old fallows with Piper aduncum, Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea. The experiment was conducted on a high base status soil (Typic Eutropepts), and in Papua New Guinea such soils are intensively used for agriculture. Soil samples were taken prior to fallow establisment and after one year when the fallows were slashed and above ground biomass and nutrients measured. The above ground and litter biomass of piper was 13.7 Mg dry matter ha^-1, compared to 23.3 Mg ha^-1 of gliricidia and 14.9 Mg ha^-1 of imperata. Gliricidia produced almost 7 Mg ha^-1 wood. Total above ground biomass returned to the soil when the fallows were slashed was the same for piper and gliricidia (8 Mg ha^-1). Gliricidia accumulated the largest amounts of all major nutrients except for K, which was highest in the above ground piper biomass. Imperata biomass contained the lowest amount of nutrients. The largest stocks of C, N, Ca and Mg were found in the soil, whereas the majority of P was found in the above ground biomass and litter. Almost half of the total K stock of piper and gliricidia was in the biomass. During the fallow period, soil organic C significantly increased under gliricidia fallow whereas no net changes occurred in piper and imperata fallows. The study has shown large differences in biomass and nutrient stocks between the two woody fallows (piper, gliricidia) and between the woody fallows and the non-woody fallow (imperata). Short-term woody fallows are to be preferred above grass (imperata) fallows in the humid lowlands of Papua New Guinea because of higher nutrient stocks.     

穗条年龄、粗度与插穗切口处理对细叶青蒌藤扦插繁殖的影响

[目的]探索穗条年龄、粗度与插穗切口处理对细叶青蒌藤扦插繁殖的影响。[方法]在福建沙县进行细叶青蒌藤扦插试验,研究穗条年龄、粗度与插穗切口处理对细叶青蒌藤扦插繁殖的影响。[结果]穗条年龄、粗度与切口位置与方法对细叶青蒌藤扦插繁殖的成苗率及新梢长度均有着极显著性差异性影响（P〈0．01）。1～2年的穗条的成苗率与梢长显著优于3～4年穗条的扦插繁殖效果（P〈0．05）;3～4年穗条的成苗率与梢长显著优于5年以上穗条的扦插繁殖效果（P〈0．05）。大于0．20cm粗度穗条扦插繁殖的成苗率与新梢长度显著优于小于0．20cm粗度穗条（P〈0．05）。节下1．5～2．5cm的插穗切口位置效果优于2．5～3．5cm的,单削斜口处理效果优于平剪处理。切口位置因素效应均大于切口处理因素,双因素的交互作用不显著（P〉0．05）。[结论]该试验进行了细叶青蒌藤扦插繁殖的穗条年龄、粗度、切口处理方面的研究,发现在节下1．5～2．5cm进行单削斜口的穗条处理结合效果最好。     

模拟胃液条件下假蒟叶提取物抑制亚硝化反应的研究

[目的]研究不同溶剂的假蒟叶提取物对亚硝化反应的影响。[方法]在模拟胃液条件下,测定假蒟叶提取物亚硝酸盐清除率及亚硝胺合成阻断率。[结果]不同溶剂的假蒟提取物均有一定的抑制亚硝化反应作用,其中乙酸乙酯提取物的抑制作用最强,且其对亚硝酸盐的清除率及对亚硝胺合成的阻断率在一定的浓度范围内随其浓度的增加而增加,对亚硝酸盐清除能力较强,其IC50值为0.425mg/ml,对亚硝胺合成阻断的能力相对较低,其IC50值为4.064 mg/ml。[结论]假蒟叶提取物具有较好的亚硝化反应抑制活性且主要通过清除底物亚硝酸盐来实现。     

胡椒脱粒去皮机的设计

胡椒(Piper nigrum)的脱粒和去皮在生产白胡椒的时候需要消耗较大的人力,为了解决这个问题,设计了一种胡椒脱粒去皮机.胡椒脱粒去皮机以电动机作为动力机构,以带传动及轴传动方式进行动力的传输.设计的胡椒脱粒去皮机将胡椒的脱粒、去皮集为一体,工作效率能达到15 kg/h,可以提高白胡椒的制作效率,降低农民的劳动强度.     

Analysis of genetic diversity in Piper nigrum L. using RAPD markers

RAPD analysis was conducted in 22 cultivars of P. nigrum(black pepper) from South India and one accession each of P. longum and P. colubrinum. Twenty-four primers generated 372 RAPD markers of which 367 were polymorphic. Jaccard's similarity between pairs of accessions ranged between 0.11 and 0.66 with a mean of 0.38. Among P. nigrum cultivars, the similarity ranged between 0.20 and 0.66 and the mean was 0.42. The existence of wide genetic diversity as revealed in the present study is supported by earlier reports of extensive inter- and intrapopulation morphological variability in pepper cultivars from South India. UPGMA dendrogram and PCO plot revealed P. colubrinum to be most distant of the three species. Genetic proximity among P. nigrum cultivars could be related to their phenotypic similarities or geographical distribution. Greater divergence was observed among landraces than among advanced cultivars. Landraces grown in southern parts of coastal India and those grown in more northern parts were grouped in separate clusters of the dendrogram.     

Modeling the Potential Geographic Distribution of Black Pepper（Piper nigrum）in Asia Using GIS Tools

Known as the "king of spices",black pepper (Piper nigrum),a perennial crop of the tropics,is economically the most important and the most widely used spice crop in the world.To understand its suitable ...     

Augmented growth of long pepper in response to arbuscular mycorrhizal inoculation

Arbuscular mycorrhizal (AM) technology is a soil-based fertilization practice for sustainable crop productivity. We evaluated six indigenous Arbuscular mycorrhizal fungi (AMF) strains for their symbiotic response with Piper longum (long pepper), a non-timber forest product holding promise as a commercial crop for its medicinal fruits and roots. Piper saplings were raised in a 10 cm thick sand and soil mix inoculated with various AMF. Under field conditions, plants inoculated with AMF demonstrated better survival (≥80%) than non mycorrhizal plants (58%). Almost all the studied AMF strains increased the plant growth, biomass and nutrient content (N and P) over the uninoculated control. Mycorrhizal inoculation with four AMF species, viz: Glomus fasciculatum, G. clarum, G. etunicatum and G. versiforme greatly enhanced long pepper growth both in the nursery and field conditions.