Potato viruses in China

Potato (Solanum tuberosum L.) is globally the fourth largest staple crop after rice, wheat and maize. China is the largest potato producer worldwide, accounting for 26.3% and 22.2% of the global total area and yield, respectively. Viral diseases have been a limiting factor for sustainable production of potato in China. This article provides update and comprehensive information on the most important viruses, their effect on yield and their control in China. Meristem culture is currently the most widely used technique for production of virus-free potato plants and these plants are used as nuclear stock for the production of certified seed tubers. Although a significant increase in tuber yield has been achieved using certified seed potatoes, lack of application of a national seed potato production scheme has hindered progress. Conventional breeding using virus-resistant cultivars introduced from other countries as parents has already led to the production of Chinese cultivars. Use of virus-resistant wild Solanum species and genetic transformation techniques will provide new virus-resistant varieties in the future to further enhance control of potato viruses in China.     

Field evaluation of yield effects on the U.S.A. heirloom sweetpotato cultivars infected by Sweet potato leaf curl virus

The incidence of Sweet potato leaf curl virus (SPLCV), a Begomovirus, on sweetpotato, Ipomoea batatas (L.) Lam. (Convolvulaceae), in South Carolina, U.S.A. has increased rapidly in recent years. This is likely due to the use of infected propagating materials and the increasing population of its vector, the sweetpotato whitefly, Bemisia tabaci (Gennadius). In this study, we demonstrated in field experiments that SPLCV infection reduced the yields of most heirloom sweetpotato lines relative to the yields of non-infected plants. Real-time polymerase chain reaction (PCR) technology specific to several common sweetpotato viruses was used to determine the virus infection status in 69 selected accessions of heirloom sweetpotato lines. Meristem tip culture technology was used to regenerate virus-free plants from these materials. To ensure the virus-free status, each mericlone was evaluated using real-time PCR and graft bio-indexing on the indicator species, Ipomoea setosa Ker Gawl. Mericlones of 27 cultivars were found to be free of the viruses. The 27 cultivars were included in a field test to determine the effect of SPLCV infection on yield. Yields of virus-free plants of the cultivars ranged from 10 to 80% greater than the yields of SPLCV-infected plants. However, the yield differences between virus-free and infected plants were diminished in the second year of the field experiment due to a rapid re-infection by SPLCV. These results demonstrate the importance of using certified, virus-tested seed roots or cuttings. The rapid re-infection of the virus-tested sweetpotato plants with SPLCV observed in these studies suggests that management of the whitefly population should be a critical element in control of this important virus.     

Disease eradication and propagation of the initial seed potato material in Estonia

Summary The EVIKA Research Centre has developed a disease eradication system for the initial material of seed potato, which consists of 1. Selection of the initial material for eradication, plant thermotherapy, meristem tip cultivation and testing for viruses; 2. Re-eradication (thermotherapy of test-tube plants, cultivation of meristem tips, testing for viruses, testing of varietal quality and yield of disease-free meristem clones, and the selection of meristem clones with best varietal characteristics; 3. Renewing of the initial material (all processes as above, but the initial material is selected from the seed potatoes grown for at least 3 years in the field). Field trials were conducted after the second cycle of eradiaction to determine whether the plantlets were true-to-type and to assess the yield, disease resistance and tuber dry matter. Recently we have also started in vitro testing of meristem plants resistance to late blight, hoping that this approach will improve the selection efficiency. Propagation and growing of the seed tubers consists of 3 main steps: 1. Plantlet propagation in vitro; 2. Greenhouse propagation in plastic rolls; and 3. Planting the first generation tubers in the field. Under our conditions it is the cheapest, simplest and most effective way. Multiplication of the meristem-derived plants is done by shoot tip cuttings in a greenhouse in plastic rolls with peat as the growing medium. The first generation of seed tubers is grown in the field. In our trials plant productivity was affected by the method of multiplication, growing conditions and genotype. The highest yield per hectare was obtained with plants multiplied in plastic rolls. The in vitro plants had more tubers per plant than plants multiplied in plastic rolls. In seed production fields the productivity of plants was more influenced by following our instructions than by multiplication and growing methods. The number of tubers per plant obtained with over 0.5 million plants was 6.5–9.0. In the second generation of seed tubers, grown under equal density, the greater-sized tubers gave more tubers with lower weight than the smaller-sized tubers. Cutting tubers had no effect on the plant development and tuberization.     

西南山区马铃薯病虫害状况分析

西南山区由于其立体气候的多样性而使马铃薯发生多种病虫害,造成产量的不稳定性。通过一系列的问卷调查和大田观察取样以及实验室病理检测,结果说明晚疫病、病毒病和青枯病是本地区最重要的病害。晚疫病常年造成１０％～３０％的产量损失,且每隔数年有一次大流行而造成更大的产量损失。种薯因病毒和其它病菌感染而不同程度地影响到产量的发挥。青枯病的发病规律较为复杂且较难预测控制。这几种病害的发生程度与作物生长季节、海拔、种薯年龄、品种、农艺措施等等密切相关。现有品种间发现有抗晚疫病和青枯病的差异。土样根系样中发现有各种寄生性线虫存在,但其危害性特别是与青枯病的关系有待进一步研究明确。２８星瓢虫是本地区危害最重的害虫。本文还列举讨论了各种病虫害防治措施。     

Combined effects of potato viruses X and S on yield of Netted Gem and White rose potatoes

Eradicating potato viruses X and S from Netted Gem (Russet Burbank) and White Rose potatoes increased their yielding potential by 11 to 38% in British Columbia, Oregon and California but there was no yield increase in Washington. The virus-free plants produced 10 to 32% more tubers than infected ones.     

The potato genetic resources held in trust by the International Potato Center (CIP) in Peru

Summary Potatoes account for about half of the world's annual output of all roots and tubers, and since the early 1960s, the increase in area planted in developing countries has been higher than for any other major food crop. Annual world production currently totals 274 million tons on 18 million hectares, with China and India accounting for 22 percent of this total. In less than a generation, most of the world's potatoes will be harvested in Asia. Africa, or Latin America, where the potato is becoming an increasingly important source of food and its cultivation provides rural employment and income for the growing population. The rapid emergence of processing facilities for the fast food industry, and the indirect influence of improved rice and wheat irrigation systems have also contributed to the expansion of potato production in Asia. The demand is strongest for processing quality potatoes that supply the fast food chains in large urban concentrations where processed potato products fetch top prices. Such increasing demand is putting strong pressure on national and international breeding institutions to produce high quality processing varieties well adapted to the wide array of agro-ecological conditions, in South East Asia in particular. The lack of adequate seed systems in this region is the single most important impediment to the expansion of the cultivation of the crop. Unfavourable agro-ecological conditions interfere with the production of high quality seed in most Asian potato growing areas, and the availability of high quality seed of the right quantity at the right time remains the most consequential bottleneck to efficient potato production. The seed issue is also the principal problem of potato cultivation in the traditional potato growing areas of Central and Eastern Europe. A review of “the development of integrated systems for large scale propagation of elite plants using in vitro techniques” with specific focus on “potato seed production by tissue culture” is therefore very timely. It provides a platform for analysis and discussion of solutions for some of the most common seed problems facing the potato industry in many parts of the word. All efforts to improve the potato crop and to solve the associated seed problems begin with the right choice and use of the available genetic resources. Resistance to certain pests and diseases has a direct bearing on the success of a seed program. Multiple virus resistance, in particular, would ensure a halt to seed degeneration caused by an accumulation of viruses and thus greatly prolong the ability of seed producers and ware potato growing farmers to grow their crops at great economic benefit. This paper will therefore deal with the current status of the World Potato Collection held in trust by the International Potato Center (CIP) in Peru by presenting up-to-date information on its classification, phytosanitary status and availability of the genetic material and its evaluation data to the breeders worldwide.     

Effect of the ring rot pathogen and latent potato viruses on ring rot symptoms and yield of potatoes

The ring rot bacterium,Corynebacterium sepedonicum (Spieck. and Kotth.) Skapt. and Burkh., and latent potato viruses (potato virus S and potato virus X) were investigated for their effect on ring rot symptom development on potato plants in the greenhouse and on symptom development and yield of potatoes in the field. Both virus-free (VF) and virus-infected (VI) Red Pontiac stem cuttings root-inoculated with ring rot bacteria in the greenhouse developed typical (T) ring rot symptoms, and symptom severity did not differ between VF and VI plants. In a field study, both VF and VI Russet Burbank seed pieces knife-inoculated with ring rot bacteria produced plants with atypical (A) and T ring rot symptoms as well as a combination of both types. The data suggest that more A than T symptoms develop on VI plants and more T than A symptoms develop on VF plants. Combined infection with the ring rot pathogen and the latent potato viruses resulted in greater yield losses of total and marketable Russet Burbank tubers than infection with the bacterial or viral pathogens alone.     

马铃薯二年制脱毒种薯体系建设及其关键技术改良

马铃薯脱毒种薯生产和利用是马铃薯生产的重要环节,传统的脱毒种薯生产体系因繁殖周期长,病毒再侵染风险高,使种薯质量很难保证。本研究以品种脱毒和试管薯生产为基础,以微型薯生产和标准种薯生产为扩繁环节,建成了二年制种薯生产体系。该体系将种薯生产在田间多年繁殖改进为只需一年繁殖,从而降低了病毒再侵染机率,保证了脱毒种薯质量。     

辽宁省马铃薯繁育体系建设研究报告

建立健全良种繁育体系,是推广应用脱毒薯的必要条件。3年来,本溪所已完成高山地区3级繁育体系的研究;大连所建立了春繁夏播2年4级的繁育体系;蚕业所建立了冷藏夏播3级繁育体系;建平示范场建立了高海拔3级繁育体系。以上4种体系各具特色,为推广脱毒薯提供了可行的模式。     

四川省马铃薯种薯体系现状、问题和对策

受立体气候条件影响,四川省不同地区一年四季均有马铃薯种植和收获。自2006年来全省马铃薯年种植面积已达到60万hm2以上,2009年达到了73.3万hm2。全省需要种薯量达到了近150万t,其中来自农民自留种的比例约为70%,外购种薯约占30%。虽然各级部门正想方设法改进种薯体系,但存在着优质种薯供应量不足、三代种薯体系尚未建立、质量控制体系尚未健全和种薯质量较差等问题,造成全省马铃薯产量长期徘徊在每公顷16.5~17.9 t之间。通过建立省级基础脱毒种苗供应中心、建立三代种薯体系、增加各级种薯生产能力、改进种薯贮藏条件、提高自留种薯质量和规范种薯繁供体系,将迅速提高全省种薯质量,促进马铃薯产业健康发展。     

Innovative propagation methods in seed tuber multiplication programmes

Summary The production of large volumes of vitroplantlets and greenhouse tubers for increasing the rate of multiplication at the start of seed programmes provides the opportunity of reducing the total number of field generations grown before the seed moves into commerce. This implementation is especially useful for countries where high quality potato seed tubers cannot be produced because there are no vector-free production areas. This review covers the following steps: a) laboratory production of microplantlets and microtubers; b) minituber production in the glasshouse; c) storage and dormancy of micro- and minitubers; d) field performance of micro- and minitubers compared with conventional seed tubers; e) incorporation of the mentioned propagules in seed production systems. Many optimized protocols are already available for propagating plantlets, inducing microtubers and obtaining minitubers in the glasshouse at all periods of the year. Advanced molecular approaches techniques (RFLP and RAPD) to detect genetic variation in the progeny of these propagules have been described. Investigations carried out in this field have shown genetic stability, with the propagules usually reproducing plants true-to-type and tubers without deviants. By contrast, variations were demonstrated in DNA extracted from old suspension cell culture. Field trials assessed a lower yield potential crops from in vitro propagules compared with conventional seed tubers., mainly due to slow early crop development and the failure of plants caused by early stress after emergence. This may cause problems when the growing season is short because of the necessity for planting late to avoid night frosts and the mandatory haulm killing dates, common in many seed producing areas. Strategies for improving the field performance of micro- and minitubers are discussed. The most promising crop husbandry techniques appear to be: a) using tubers of a suitable physiological age, properly presprouted and encapsulated; b) optimizing the time application of fertilizer and irrigation, and c) using floating films. Outside the classical seed tuber areas of Northern Europe where the length of the growing period for pre-basic seed is usually not more than 80 days, the growing season is long enough to obtain reasonable yields even from micro- and minitubers.     

Impact of transgenic viral resistance on seed potato certification

It was nearly 100 years ago that the decline in quality and yield observed in potato crops was attributed to the accumulation of pathogens in seed tubers saved from one field generation to the next. As a direct result of this realization, seed potato certification programs have been initiated throughout the world. While these programs have different administrative structures and employ various methodologies, they are all dedicated to the primary goal of producing a sufficient volume of high quality seed tubers as free from disease causing organisms as possible. Viral diseases are especially problematic because they have serious economic affects and their physical and biological properties make them difficult to control. Until recently, certification programs have relied on methodologies including the use of virus-free material obtained from tissue culture, strict adherence to practices that minimize the mechanical and insect spread of virus, physical inspection of seed increase plots to identify and minimize the number of virus-infected plants, and the increase of seed materials for only a limited number of years to insure that any infected materials are “flushed out” of the system. Approximately 10 years ago, it was first observed that virus resistance can be obtained by using transformation techniques to insert viral genes into the genome of plants. Subsequently, researchers in private and public laboratories have shown that potato plants produced in this way are highly resistant or immune to several viral diseases. The effect that the deployment of these materials may have on the seed potato certification process is the subject of this paper.     

马铃薯脱毒原原种微型化生产和微型薯应用

马铃薯脱毒原原种微型化生产的技术关键在于控制植株个体生长;而其首要条件是种苗基础和营养水平.利用普通日光温室,在瓶苗假植或使用已有的微型薯育苗的基础上,采取砂床剪枝扦插和高密度少肥栽培生产微型薯,比移栽瓶苗或直播微型薯的办法更好.即在剪枝扦插后40天收获,平均获得单薯重1～5克的微型薯个数占总数的(76.0～91.6%,最高达100%.单薯重1克以上的4个规格1～3克、大于3克、大于5克、大于10克)微型薯直播亩产达1806～2194公斤,接近或超过大薯切块直播(1962公斤/亩),但4个规格微型薯的含量不呈规律性差异.单薯重小于1克的微型薯育苗移栽亩产达2299公斤,略高于大规格微型薯直播产量.但考虑其利用价值,将单薯重小于1克的微型薯作为脱毒原原种微型化生产的基础种苗使用更合适.     

The effect of water stress on the yielding capacity of potato crops and subsequent performance of seed tubers

Summary The effect of water stress on yielding capacity of potatoes was studied in 3 years using four different levels of soil water potential (0.7, 1.9, 3.4 and 7.8 atm.) in experiments in specially adapted structures that excluded uncontrolled water supply. Seed tubers from these crops were planted in the following years to investigate effects of water stress on their subsequent performance. Limited soil moisture availability decreased yield and the number and size of tubers. The growing period was shortened by 1–4 weeks and dormancy period by 2–8 weeks. In the following year, seed produced under conditions of moisture stress gave plants with 20% fewer stems. 24–33% less yield, 18–22% fewer tubers and 19–22% fewer large tubers than plants from seed produced under abundant water supply. It is concluded that the yield potential of seed tubers can be improved by careful attention to the availability of soil moisture during their production.     

河北省一季作区马铃薯病虫害发生及综合防控

河北省一季作区马铃薯主要病虫害有晚疫病、早疫病、黑痣病和二十八星瓢虫,此外,病毒引起的品种退化比较普遍,造成不同程度的损失。本文根据河北省一季作区马铃薯病虫害发生特点总结出一套综合防控技术体系,包括将马铃薯与玉米、大白菜等非茄科作物轮作3年减轻黑痣病危害;采用脱毒薯克服病毒引起的品种退化问题;种薯和(或)土壤消毒控制黑痣病和晚疫病;待马铃薯生长至封垄后,遇到适宜晚疫病发生的天气,喷施1～3次保护性杀菌剂预防晚疫病和早疫病;一旦监测到晚疫病中心病株后即拔除并装入塑料袋带出田外,并交替喷施有治疗效果、能兼治早疫病且作用机制不同的内吸性杀菌剂及混剂;田间出现马铃薯二十八星瓢虫成虫,在杀菌剂中混入高效氯氰菊酯或高效氯氟氰菊酯等高效杀虫剂防虫;马铃薯成熟前1～2周将地上部分割掉并运出田外后收获块茎。     

马铃薯脱毒种薯的快速繁殖技术

马铃薯退化现象是由于感染一种或多种过滤性病毒引起的,它是影响高产稳产的主要因素。病毒不仅赖于植物体内部生存,并且参加和改变植物体内许多代谢途径的生理活动。当被不同病毒侵染的马铃薯出现各式各样症状,就是病毒在植物体内部干扰机体代谢作用的结果,所以只有从内部清除病毒,获得脱毒健康种薯,才是治本的办法。     

我国花生生产发展现状与潜力分析

我国花生生产与消费近十年来持续增长,2018年总产量和花生油产量分别达到创纪录的1733万吨和294万吨,在国内油料作物中花生的总产量、总产值、单产水平、单位面积产油量、单位面积种植效益、国际竞争力等方面存在诸多比较优势。本文除全面总结全国花生生产与利用进展外,还概述了花生对食物安全的保障作用、科技创新对花生产业发展的支撑作用,讨论了花生生产存在的问题和发展潜力,并对未来花生产业发展目标和主要对策提出了若干建议。     

我国马铃薯病毒的种类及脱毒种薯生产过程中病毒的检测

对近年来我国各马铃薯产区病毒发生情况进行分析,详细列出马铃薯主产区病毒病种类及各主要马铃薯病毒的分布情况。分析表明,我国很多马铃薯产区尚缺少全面、系统的马铃薯病毒调查。同时比较了我国各地区马铃薯脱毒种薯生产过程中对病毒的检测规程,并分析了马铃薯A病毒(PVA)的检疫风险。     

The quality of seed tubers multiplied in the Golan Heights for the spring season in Israel

Summary Seed tubers grown in the northern mountain region — the Golan Heights — were as productive as imported seed tubers. In cvs. Blanka and Désirée, both the locally grown and the imported seed tubers were similar when yield components and tuber fresh weight are considered. In Up-to-Date, the locally grown seeds produced higher yields of marketable tubers (over 60 g/tuber) than those imported. Désirée seed tubers grown for two generations in the Golan Heights did not differ significantly in their productivity as compared with common Golan seeds and with imported ones. Seed tubers harvested from plots which were protected by means of white coarse nets and weekly sprays with insecticides, were virtually virus-free and were used for growing commercial seeds in the Golan. The use of this method for seed multiplication is suggested. Contribution from the Agricultural Research Organization. The Volcani Center, Bet Dagan, Israel. No 137-E, 1981 Series.     

Effect of seed tuber and seed piece size on growth and incidence of hollow heart in Norgold Russet potatoes

Small seed pieces decreased yield and number of tubers. Both seed tuber and seed piece size affected the percentage of tubers with hollow heart. Hollow heart increased from 14 to 22% as the seed tuber size increased from 57 to 228 g and decreased from 27 to 19% as the seed piece size increased from 28 to 57 g. The least hollow heart (11%) occurred in tubers of plants grown from 57 g whole seed pieces and the most (26%) in tubers of plants grown from 228 g seed tubers cut into 28 g seed pieces. Hollow heart was positively correlated with the mean tuber size and negatively correlated with the number of mainstems per hill, total yield, and total number of tubers.