Modelling nematode population growth and damage

Recent results on the population dynamics and damage relationships of root-knot nematode (RKN, Meloidogyne incognita) and of potato cyst nematode (PCN, Globodera pallida) are modelled, and a computer-based programme is used to explore different strategies for PCN control. Damage by RKN was shown to be density dependent, to increase with increasing duration of plant growth, and to be much greater for good than poor hosts. PCN populations both increase and decline more slowly than those of RKN, and modelling suggested that, when non-hosts are grown, differences in decline rates will have an accumulative effect on the effectiveness of rotation. Similarly, differences in nematicide effectiveness will have a major effect on post-harvest PCN populations, and nematicides were shown to be most effective when PCN populations are small. Host resistance is a key component of integrated management of nematodes and, because gene flow in soil is limited, it can be durable.     

Potato production and incidence ofVerticillium dahliae following rotation to nonhost crops and soil fumigation in the state of Washington

For three years, potato yields, tuber quality, and incidence ofVerticillium dahliae were measured in field plots previously cropped for one year to the following nonhosts: sudan grass, green peas followed by sudan grass (same year), spring wheat, spring wheat followed by sudan grass (same year), sweet corn and field corn. One year rotation to nonhosts did not reduce the population ofV. dahliae propagules in the soil and in only one of the three years wereV. dahliae propagule numbers in potato stems significantly reduced in plots following nonhost crops, compared with plots following potatoes. Verticillium wilt symptoms in potatoes were not reduced by one year rotation to any of these crops and only in one year in three was yield significantly increased. In two of three years, percent U.S. No. 1 tubers was increased following one-year rotation with green peas plus sudan grass, and in one of the two years, specific gravity was increased by rotation. Rotational cropping to nonhosts for two years between potatoes significantly reduced preplant soil populations ofV. dahliae propagules in the soil and in potato stems the following fall. However, soil populations in these two year rotational plots the spring following potato were not reduced compared to plots previously cropped to potatoes two consecutive years. Cropping to nonhosts for two years had no consistent effect on incidence of Verticillium wilt in subsequent potato crops. Two years’ rotation to nonhosts increased plant height and yield compared to continuous cropping to potato but not percent U.S. No. 1 tubers. The various nonhost crops all had about the same non-significant effect on yield. In two out of three years’ trials, fumigation significantly reduced both the incidence of Verticillium wilt and number ofV. dahliae propagules in stems in plots compared to plots non-fumigated. In only one trial, fumigation significantly increased tuber yields and percent U.S. No. 1 tubers.     

Lesion nematode suppression with the butte potato and relationships to verticillium wilt

Field studies conducted over a 5 yr period to compare the effect of continuous cropping of several potato clones (Butte, Russet Burbank, Targhee, A66107-51, and A68113-4) showed Butte to be highly resistant toPratylenchus neglectus while being highly susceptible toVerticillium dahliae. This was further evidenced during the 6th yr when Russet Burbank was cropped over all plot-locations. Populations ofP. neglectus were shown to be significantly less (0.05 P) in both soil and roots when Russet Burbank was grown over sites previously cropped with the Butte potato than over site-locations cropped by either Russet Burbank, Targhee, A66107–51, or A68113–4. Additional field and greenhouse studies corroborated the high degree of resistance of Butte toPratylenchus spp. In addition toP. neglectus resistance, a greenhouse investigation also showed resistance to P. penetrans. A field study designed to compare the effects of Butte with nematicides showed that Butte reducedP. neglectus populations in both soil and roots when compared with Russet Burbank. This degree of reduction was equivalent to the effects of either of two systemic nematicides (aldicarb and isofenphos) at 3.4 to 4.0 kg a.i./ha, respectively. Results demonstrate biological control with the Butte potato clone forP. neglectus suppression. Although populations ofP. neglectus were reduced by either nematicides or Butte, wilt severity was higher with Butte than Russet Burbank. Results showed wilt suppression andP. neglectus reduction with treatments of either nematicide, while having no significant effect on the colonization of potato stems byV. dahliae.     

Continuation of cropping sequence studies on coarse textured soils in southeastern Idaho

A potato cropping rotation study was initiated on coarse textured soils in 1969 to compare annual cropping to potatoes with potato-grain rotations. At the completion of the 1975 season, those treatments annually cropped to potatoes had been planted to potatoes for seven consecutive years. After this period of time, total yields were reduced by 14% or 55 cwt/acre (6 T/ha) when compared to yields from potato-grain rotation treatments. Soil fumigation with 30 gpa (285 1/ha) of soil fumigant (Shell D-D) resulted in no beneficial effects on tuber yield or quality.     

Response of two sweet potato cultivars to weed interference

Field experiments were conducted at the U.S. Vegetable Laboratory, Charleston, SC, U.S.A in 2000, 2001, and 2004 to assess the effect of different durations of weed interference on two sweet potato cultivars with different shoot growth habits. The cultivars were Beauregard, which has a spreading growth habit that is typical of U.S. sweet potato cultivars and Carolina Bunch, with an erect growth habit. Weed interference treatments included control plots that were maintained weed free throughout the growing season and plots that were maintained weed free for 0, 10, 20, and 30 days after transplanting. In general, Carolina Bunch was more tolerant of weed interference than was Beauregard. In two of three years Carolina Bunch storage root yields were higher than Beauregard yields in plots that received no weeding; whereas, yields of the two cultivars in weed free plots were not different. Weed interference affected shoot growth to a greater extent than it affected storage root production. At the end of the growing season, Carolina Bunch shoot biomass was greater than Beauregard shoot biomass in plots receiving no weeding and in plots that were maintained weed free for 10 days in all three years. Shoot biomasses of the two cultivars were not different in weed-free plots. Weed shoot biomasses were greater in Beauregard plots than in Carolina Bunch plots in several instances. These results demonstrate that sweet potato cultivars with a vigorous, erect shoot growth habit (with shorter stems, greater branching, and a denser and taller canopy early in the growing season) may be less susceptible to weed interference than cultivars with spreading shoot growth. This study also confirmed previous observations that sweet potato productivity is not greatly affected by moderate weed interference; thus, it may not require intense weed management to produce high yields.     

Effects of Baking and Boiling on the Nutritional and Antioxidant Properties of Sweet Potato [<Emphasis Type="Italic">Ipomoea batatas</Emphasis> (L.) Lam.] Cultivars

The effects of baking and boiling on the nutritional and antioxidant properties of three sweet potato cultivars (Beniazuma, Koganesengan, Kotobuki) cultivated in Turkey were investigated. The samples were analyzed for proximate composition, total phenolic content, ascorbic acid, β-carotene, antiradical activity, and free sugars. The dry matter, protein, and starch contents of the sweet potatoes were significantly changed by the treatments while the ash and crude fiber contents did not differ as significantly. The β-carotene contents of baked and boiled sweet potatoes were lower than those of fresh sweet potatoes; however, the total phenolic and ascorbic acid contents of the baked and boiled sweet potatoes were higher than those of the fresh samples. Generally, the antiradical activity of the sweet potatoes increased with the treatments. Sucrose, glucose, and fructose were quantified as free sugars in all fresh sweet potatoes; however, maltose was determined in the treated samples. In terms of the analyzed parameters, there were no explicit differences among the sweet potato cultivars.     

重迎茬大豆对土壤有机—无机复合胶体及土壤结构的影响

重、迎茬大豆对黑土和暗棕壤的影响为；有机质，重组有机质，复合有机质及复合度均为重，迎茬低于正茬，石灰性黑钙土则相反；复合体中不同结合态腐殖质及Ｅ４／Ｅ６变化不尽相同；水稳性团聚体在三种土壤中重，迎茬呈下降趋势，重迎茬对土壤结构有损伤。     

Stability of Carotenoids, Total Phenolics and In Vitro Antioxidant Capacity in the Thermal Processing of Orange-Fleshed Sweet Potato (Ipomoea batatas Lam.) Cultivars Grown in Brazil

Intervention strategies regarding the biofortification of orange-fleshed sweet potato, which is a rich source of carotenoids for combating vitamin A deficiency, are being developed in Brazil. This study was conducted to evaluate the concentrations of individual carotenoids, total phenolic compounds and antioxidant capacity in the roots of four biofortified sweet potato cultivars that were raw or processed by four common heat treatments. HPLC, Folin-Ciocalteu, DPPH and ABTS assays were used. All cultivars showed high levels of carotenoids in raw roots, predominantly all-trans-β-carotene (79.1-128.5?mg.100?g(-1) DW), suggesting a high estimated vitamin A activity. The CNPH 1194 cultivar reported carotenoids values highest than those of other cultivars (p?相似文献   

侵染湖南甘薯种质资源的曲叶病毒和杆状病毒的检测及其亲缘关系分析

采用PCR技术对2015—2016年从湖南省多个市县采集的180份甘薯种质资源进行两种DNA病毒（sweet potato leaf curl virus,SPLCV和sweet potato badnavirus,SPBV）检测,并以PCR扩增产物序列为基础,对这两种病毒的亲缘关系进行分析。结果表明：（1）180份甘薯种质资源中,22份检测出SPLCV,占总数的12.2%;32份检测出SPBV,占总数的17.8%;8份同时检出SPLCV和SPBV这两种病毒,占总数的3.9%。（2）检出SPLCV的市县有长沙、永州、怀化、邵阳、郴州、常德、娄底、益阳、岳阳和株洲;检出SPBV的市县有长沙、永州、怀化、衡阳和邵阳;检出两病毒复合侵染的市县有怀化、长沙、永州和邵阳。（3）基于病毒全基因组序列分析显示,全球已报道的36个SPLCV分离物可分为3组,本研究获得的12个湖南分离物可分别归于3个组中,其中6个归于组Ⅰ,1个归于组Ⅱ,5个归于组Ⅲ,表明湖南SPLCV具有高度多样性。（4）基于病毒运动蛋白和外壳蛋白编码基因部分序列分析显示,全球已报道的36个SPBV分离物可分为4组,绝大部分分离物属于组Ⅰ,我国1个安徽分离物单独成组（组Ⅱ）,我国2个山东分离物和1个海南分离物构成1个组（组Ⅲ）,本研究获得的2个湖南分离物其中1个归于组Ⅰ,而另1个与已报道各分离物的核苷酸序列均存在显著差异,相似性仅为74.92%,单独成组（组Ⅳ）,表明我国SPBV具有高度的变异性,存在多个变异类型。本研究结果可为湖南地区这两种病毒病防控提供依据。     

4种蔗糖分解酶在甘薯块根品质形成中的作用

本研究以2个在可溶性糖和淀粉含量上存在显著差异的鲜食型甘薯品种为材料,对其块根中的可溶性糖（蔗糖、葡萄糖和果糖）和淀粉含量以及4种蔗糖分解酶的活性进行测定与相关性分析,以明确调控甘薯块根中可溶性糖和淀粉含量的关键蔗糖分解酶种类。结果表明：（1）明确甘薯块根中活性最高的蔗糖分解酶为蔗糖合成酶（Sus）,其次为细胞质转化酶（CIN）和液泡转化酶（VIN）,细胞壁转化酶（CWIN）的活性最低。（2）本研究表明,除了已报道的VIN外,CIN活性也和己糖含量之间呈显著正相关,高己糖含量的甘薯品种块根中具有更高的VIN和CIN活性;（3）甘薯块根中Sus活性和淀粉含量之间呈极显著正相关,高淀粉甘薯品种具有更高的Sus活性;（4）CWIN活性非常低,其在块根发育中的具体作用有待进一步深入研究。总之,蔗糖分解酶对甘薯品质有重要影响,其中Sus是调控甘薯块根淀粉含量的关键酶类,而CIN和VIN是调控块根中己糖含量的关键酶类。     

菜、稻、薯三熟三高产高效栽培模式

采用菜、优质稻、甘薯水旱轮作种植模式,通过合理轮作,合理安排,科学管理,不仅提高了农田复种指数,保证粮食安全,而且获得三熟三高产、高效的经济效益。     

遮阴对淀粉型甘薯生长发育及生理特性的影响

为探究淀粉型甘薯对光照强度的响应,采用人工遮阴的方法,研究不同遮阴程度[0(CK),30%,70%]对甘薯地上部性状、产量、淀粉含量及生理特性的影响。结果表明,随遮阴程度的加重,甘薯叶片变大,节间距加大,叶柄和茎蔓伸长,茎粗变细,产量和淀粉产出率减少;叶片的叶绿素含量增加,叶绿素a/b值降低,SOD活性减小,POD活性、CAT活性、MDA含量和脯氨酸含量增加;与自然光照相比,轻度遮阴(遮阴30%)对淀粉型甘薯桂经薯2号生长发育影响较小,而重度遮阴(遮阴70%)造成弱光胁迫,地上部徒长,组织抗性降低,物质积累不足,影响了甘薯的产量和品质形成。因此,在间套种种植模式中,采用合理的田间配置才能实现高产高效。     

采后脱落酸处理促进甘薯块根愈伤木栓组织的形成

本研究以‘北京1号’甘薯为试验材料,人工模拟机械损伤后采用不同浓度（25、50、100、200 mg/L）脱落酸（ABA）进行愈伤处理,研究采后ABA处理对甘薯块根的愈伤作用。结果表明:采后ABA处理能有效促进甘薯伤口处愈伤木栓组织的形成,其中以100 mg/L ABA愈伤3 d效果最佳。采后ABA处理能有效提高甘薯愈伤组织苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）和多酚氧化酶（PPO）活性,提升总酚、类黄酮含量,减少甘薯重量损失。相关性分析表明,ABA处理甘薯木质素含量与总酚、类黄酮含量之间呈极显著相关（P<0.01）,PAL酶活力与POD和PPO酶活力呈极显著相关（P<0.01）。综上所述,采后ABA处理可通过激发甘薯损伤部位组织的苯丙烷代谢、提高愈伤防御酶活性及次生代谢产物的合成,达到促进甘薯块根愈伤形成的目的。     

Integrated assessment of cropping systems in the Eastern Indo-Gangetic plain

Both intensification and diversification of cropping systems may allow improving the productivity and sustainability of agricultural production in the Indo-Gangetic Plain (IGP), but the choices to be made require integrated assessment of various cropping systems. A field experiment was conducted from 1999 to 2002 on a sandy clay loam (Inceptisol) to evaluate nine predominant cropping systems in West Bengal, India. Productivity, energy use efficiency, and nutrient uptake generally increased with increasing cropping intensity. Positive residual effects of potato and jute on yield and energy output of subsequently grown crops were observed as well as maintenance or improvement of soil properties such as soil organic matter, available P, and available K. The P balance was positive for most systems, except for jute-containing systems. However, negative K balances occurred due to almost complete removal of crop biomass in all systems, suggesting that recommended rates of applied K fertilizer were to low for sustaining soil K supply over the longer term. Cropping systems containing potato had the highest levels of yield, net return, benefit to cost ratio and energy productivity, but energy use efficiency was reduced due to higher energy consumption in these systems. Jute–wheat and jute–rapeseed–rice systems showed high energy use efficiency along with moderate cost and return. Based on economic considerations alone, jute–potato–rice, rice–potato–rice and rice–potato–sesame can be recommended as cropping systems for resource-rich growers in the eastern part of the IGP. Systems such as jute–wheat, rice–wheat and jute–rapeseed–rice appear to be most suitable for small and marginal farmers that cannot afford the large production costs associated with crops such as potato.     

甘薯茎尖脱毒及快繁技术研究

以辽薯20等品种为试材,对辽宁省4个主栽甘薯品种的茎尖脱毒和脱毒苗快繁技术进行研究。结果表明,甘薯茎尖采用体积分数为0.05的NaClO溶液消毒10 min,采用高温（33～35℃）预培养植株2～5 mm茎尖作为外植体进行脱毒,可提高成苗率和脱毒效果。切取0.2～0.3 mm长的茎尖分生组织,在附加6-BA1.0mg/L＋NAA0.24 mg/L的MS培养基中,4个品种的茎尖培养成苗率平均为78.5%,成苗期45～60 d,加入IAA（0.02～0.05 mg/L）的MS培养基对甘薯无毒苗的快速繁殖更有利。     

甘薯生产技术规程

本规程规定了甘薯生产的产地环境、育苗、田间管理、病虫害防治、收获与贮存,适用于广州地区甘薯生产。     

索引

综述菜用型甘薯的营养成分和保健功能、育种研究进展和栽培研究现状,指出菜用甘薯作为蔬菜用与其他蔬菜相比,具有可种植区域广、可种植时间长、效益高、市场潜力大等优势。针对我国目前菜用甘薯产业化、商品化等方面存在的一些主要问题,提出相应的发展对策。     

干热变性紫薯淀粉成膜工艺优化

紫薯中直链淀粉含量较高,具有较好的成膜性。以干热变性紫薯淀粉为基质,探究变性淀粉添加量、甘油添加量和海藻酸钠添加量对干热变性紫薯淀粉成膜特性的影响,通过响应面分析法确定干热变性紫薯淀粉最佳成膜工艺参数。结果表明:当变性淀粉添加量为3.99%,甘油添加量为1.52%,海藻酸钠添加量为0.60%时,干热变性紫薯淀粉膜的性能最优。研究成果将为干热变性紫薯淀粉可食用膜的工业化生产提供理论指导。     

辽宁省马铃薯高效复种栽培技术

经过多年试验示范,针对辽宁省气候特点,总结出马铃薯高效复种栽培模式,筛选出各主产区的适宜品种和相应种植密度,为辽宁省马铃薯科学种植提供依据。马铃薯的三膜覆盖极早熟栽培技术比较适合葫芦岛地区和大连地区应用,下茬复种小西瓜等经济效益较高的作物。马铃薯双膜覆盖栽培技术可克服前期低温的不利影响,缓解晚霜冻害,比常规地膜覆盖提前收获15 d以上,其鲜薯价格高,效益可观,为下茬复种粮食和油料作物高产创造条件,比较适合在辽西和辽南的大部分地区应用。马铃薯单膜覆盖栽培技术适用于辽宁大部分地区,下茬可复种蔬菜、粘(甜)玉米等作物。     

UV-C处理对甘薯贮藏品质的影响

以海南桥头产区的“高系14”甘薯为材料,分别进行10、20、30 min的UV-C照射处理,统计甘薯贮藏60 d内的腐烂率、失重率和发芽率,并同时记录5种生理指标的变化,以探讨UV-C处理对甘薯贮藏品质的影响。结果表明：UV-C处理显著降低了甘薯贮藏期间的腐烂率,但同时促进了发芽,而对失重率无显著影响。生理指标方面,30 min的UV-C照射提高了可溶性蛋白的积累,减少可溶性固形物的损耗,并促进了POD、SOD和CAT的总体酶活性。综合来说,UV-C处理若要应用于甘薯贮藏保鲜,还需辅助使用其他的抑芽手段。