Relation of potato compsition to potato size and blackening tendency

A compositional study was conducted on six potato samples representing various degrees of stem-end blackening. The aim of the study was to determine compositional variation with potato size. The compositional characteristics, of stem-and bud-end tissue of various potato sizes, of the six samples were determined. The larger the potato the greater was the tendency for the stem-end to have the following characteristics: (i) low citric acid content, (ii) high K/citric acid, and (iii) relatively low citric acid/polyphenolic content. It was also shown that differences in stem-end blackening tendency between potato samples, as well as differences in blackening within the same sample could be correlated with these same compositional characteristics.     

Photo-induced changes in the concentrations of individual chlorogenic acid isomers in potato (Solanum tuberosum) tubers and their complexation with ferric ions

Summary Changes in the concentrations of 3-, 4- and 5-caffeoylquinic acids in potato tubers exposed to light have been determined by high-performance liquid chromatography. In the first 24 to 48 hours the observed increases in total chlorogenic acid content was due primarily to an increase in 5-caffeoylquinic acid content but thereafter the rate of accumulation of the other isomers increased gradually. After 24 hours exposure 4-caffeoylquinic acid accounted for 10% of the total chlorogenic acid content of the tubers compared with 33% after 168 hours. The significance of this change in isomeric ratio on the spectral characteristics of potential ferrichlorogenic acid complexes was investigated in vitro. It was concluded that potato quality, as reflected in the development of after-cooking blackening, was dependent on total chlorogenic acid content and was unaffected by the relative concentrations of the individual isomers.     

Comparisons of Inhibitors of Tyrosine Oxidation in the enzymatic blackening of potatoes

Sodium bisulfite, cysteine, dithiothreitol, and sodium diethyldithiocarbamate (Na Dieca) inhibit enzymatic blackening in potatoes by initially inhibiting the oxidation of tyrosine by polyphenol oxidase. Sodium bisulfite and Na Dieca also cause enzyme inactivation. Although cysteine and dithiothreitol inhibit tyrosine oxidation for a period of time, they do not appear to inactivate the enzyme. Dithiothreitol is a much more effective inhibitor of tyrosine oxidation than cysteine. Ascorbic and dihydroxyfumaric acids inhibit enzymatic blackening by reducing the dopaquinone to dopa. When the reducing agents are completely oxidized, blackening can occur.     

Studies on after-cooking blackening in potatoes IV. field experiments

Summary Variations in the concentration of the main biochemical factors responsible for after-cooking blackening in potatoes have been examined in a number of varieties grown on a black fen soil and a clay soil. Highly significant correlations were found between blackening and the ratio of chlorogenic acid/citric acid in the individual varieties. Blackening was usually greater in the fen grown tubers and this was generally associated with the presence of less citric acid and sometimes more clorogenic acid. The annual fluctuation in blackening at a given centre was mainly due to the different amounts of chlorogenic acid and citric acid found in the tubers under the varying climatic conditions.     

马铃薯贮藏还原糖含量与不同因素的相互关系的分析

马铃薯贮藏过程中其还原据含量受温度、体积、时间以及通风量和光照条件的影响。用夏·薛·哈(Somogyi—Shaffer—Hartmarin)三氏法测定了8541至8545、东北白和紫花白7品种(系)的马铃薯还原糖在贮藏期随温度、体积、品种以及不同时期的含量;并对正交试验数据进行了处理,得到了贮藏期还原糖含量受诸多因素影响的变化关系,结果表明,正交试验法是一种行之有效的研究方法。     

华薯和鄂薯系列马铃薯品种晚疫病抗病基因及水平抗性相关基因SNP位点检测

鄂薯和华薯系列马铃薯品种是由湖北恩施中国南方马铃薯研究中心和华中农业大学马铃薯团队选育而成的品种.鄂薯系列马铃薯品种大多为中晚熟品种,适合西南山区种植;华薯系列马铃薯品种多为早熟品种,适于华中低山丘陵和平原地区种植.研究对2个系列品种部分晚疫病抗病基因进行了分子标记检测,同时对几个水平抗性相关基因SNP位点进行了检测....     

Improvement of techniques for potato blackspot evaluation and some errors associated with measurements

Potato blackspot is a sub-epidermal blackening of tissue that results when bruising forces rupture cells of susceptible tubers. Degree of blackspot susceptibility is measured by bruising tubers and assessing the amount of discoloration that develops. Since the rate of color development is influenced by temperature, all testing was done at 21 C. Blackspot intensity was evaluated by visual inspection and by use of a photo reflectometer. A high correlation exists between reflectometer measurements and visual observations. The thickness of the paring slices affected the accuracy of susceptibility inferences. For spots ranging from 10 to 15 mm in diameter a shaving error of ± 1 mm would cause an error of about 5%, whereas on spots 5 mm or less such a shaving error would cause an error of about 20%. Reduction in peel thickness can reduce such errors appreciably. The variability in susceptibility to blackspot varies greatly both within a tuber and among tubers. In these studies 30 bruises in selected tuber locations were adequate to measure treatment differences. About 30 spots, whether obtained by bruising each of 10 tubers 3 times or by bruising 30 tubers once, resulted in about equal blackspot scores. Improvements in a previously described method for bruising and evaluating potato tuber blackspot susceptibility are described.     

马铃薯防御酶系活性与其抗晚疫病的关系

应用比较生理学方法,以6个对晚疫病抗性不同的马铃薯品种为材料,研究无病原菌浸染及病原菌浸染后抗、感病品种的马铃薯叶片中防御酶系活性的变化与其抗晚疫病的关系。结果表明:无病原菌浸染及病原菌浸染后,抗病品种比感病品种有较高的PPO、POD和-β1,3-葡聚糖酶活性。因此认为PPO、POD和-β1,3-葡聚糖酶活性与马铃薯抗晚疫病有关。另外,接种后各指标测定结果均不同程度地高于无病原菌浸染时期,表明病原菌浸染后诱导马铃薯体内与抗晚疫病有关的防御酶活性升高。本研究从防御酶活性变化方面阐明马铃薯抗病的生理基础,为马铃薯抗病生理选种提供理论依据。     

Recent Price Developments in the United States Potato Industry

An analysis of the relationship between potato prices and potato production is important for understanding industry developments. The analysis of the effect of potato production on potato prices was presented in two AJPR articles: Pavlista and Feuz (American Journal of Potato Research 82:339–343, 2005) and Loy et al. (American Journal of Potato Research 85:438–444, 2011). The articles estimated inverse potato demand in the U.S. and Germany, respectively, during the period of 1980–2003. They hypothesized that the potato price response to changes in potato production may be affected by a shift in consumer demand towards increasing consumption of processed potatoes in the U.S. and by socio-economic changes in Germany. This paper extends the existing research by analyzing the recent price developments in the U.S. potato industry. The empirical results indicate that the potato price response to changes in potato production was different during the period of 2005–2010, as compared to the periods of 1993–2004 and 2011–2016, which coincided with the implementation of the potato acreage management program.     

马铃薯氮钾肥适宜施用量研究

为确定闽东南稻稻薯三熟制中马铃薯氮钾肥适宜施用量,在龙海市设置氮钾肥水平试验。结果明确,马铃薯产量与氮钾肥施用量呈抛物线型相关,目标产量2500kg/667m2的氮、钾肥经济施用量分别为16kg/667m2和13.4kg/667m2,氮钾比1∶0.84。     

Influence of pH and bisulfite on the enzymatic blackening reaction in potatoes

The inhibition by bisulfite of the oxidation of tyrosine in the enzymatic blackening reaction was pH dependent. At a pH of 5.0 or lower, bisulfite was a very effective enzyme inhibitor. A pH higher than 5.0 resulted in much less enzyme inhibition. At a pH of 4.0, the pH alone was a very effective enzyme inhibitor while a pH of 5.0 or above did not inhibit tyrosine oxidation very much. Thus, when bisulfite was present at a pH above 5.0, the main factor inhibiting enzymatic blackening was the bisulfite. Below pH 5.0 the inhibition of the polyphenol oxidase by both bisulfite and pH was important. The inactivation of polyphenol oxidase by bisulfite was a function of time and was pH dependent. Rapid inactivation occurred at pH 4.0 while inactivation occurred much more slowly at pH 5.0, 6.0 and 7.0. The residual enzyme activities were higher at pH 5.0 or above than at pH 4.0. Reactivation of the polyphenol oxidase did not occur over a 7 day period.     

应用免疫电镜对几种马铃薯病毒毒源的鉴定研究

首次应用免疫电镜筛选出高纯度、高浓度的马铃薯毒源试管苗,为制作效价高、活性好的抗血清提供良好的抗原.论述了PVX,TMV和PVY 3种毒源在烟草寄主上繁殖时的拮抗关系,从而为马铃薯毒源繁殖和保存提供了科学依据.     

马铃薯块茎还原糖含量与各器官含磷量的关系

以克新 1号和夏坡蒂原种为材料 ,通过田间试验和室内分析测定 ,对生育期间马铃薯块茎还原糖含量的变化与各器官含磷量的关系进行了初步研究。结果表明 :马铃薯块茎中还原糖含量随生育进程逐渐减少 ;品种之间各器官含P量与块茎还原糖含量呈显著负相关 ;增施磷肥可显著提高各器官含磷量 ,从而有利于块茎还原糖含量的降低     

Assessing compensation for insect damage in mixed plantings of resistant and susceptible potatoes

Plant mixtures have been proposed for pesticidal transgenic potatoes as a means to reduce selection intensity favoring resistant insect genotypes. Colorado potato beetle,Leptinotarsa decemlineata (Say), defoliation was simulated in mixed plantings of susceptible and resistant potato “mimics” to evaluate yield compensation. Various mixtures of susceptible and resistant potato were planted at two densities and two locations in eastern North Carolina. Resistant plants were undamaged throughout the season whereas susceptible plants were completely defoliated by hand either during early or late bloom. The ability of non-defoliated plants to compensate for neighboring defoliated plants was investigated through single-plant and smallplot field experiments for 2 years. Yield compensation for defoliated plants by neighboring non-defoliated plants was not evident in our studies. Yield of two potato plants, positioned on either side of a defoliated plant, was not different from yield of two potato plants positioned on either side of a non-defoliated potato plant. Compensation in mixtures of resistant and susceptible potato was not evident using several non-linear regression analyses. A negative linear relationship existed between yield and an increasing percent of susceptible plants in the mixture for all planting densities, at each location, every year.     

Some effects of plant spacing on potato quality

Summary As plant population was increased so the dry matter content of the tubers increased, but delaying harvest had little such effect. Tubers of 2–3 cm (or 2.5–3.0 cm) had a lower dry matter content than tubers of 4.5–5.5 cm size at any one harvest. Increases in dry matter content were associated with increases in the disintegration of the tubers when cooked. The N content of the tubers was influenced by population, and although N content decreased and after-cooking blackening decreased with increasing plant population, after-cooking blackening was better related (inversely) to the K/N ratio of the tubers than to N content. Tubers from the later harvests had higher N, lower K and lower K/N ratio than those of a similar size at the earlier harvests. Published effects of fertilizer application on quality are related to similar effects obtained by varying the plant population.     

Soft-rot resistance combined with other tuber characters in long day-adaptedSolanum phureja

Summary Offspring were produced from a cross between two long-day-adaptedSolanum phureja clones which carried resistance to tuber soft rot (Erwinia carotovora subsp.atroseptica). In tests carried out on the produce of field-grown plants raised from tubers, over fifty per cent of the 173 offspring were found to be highly resistant. Assessments were also carried out of tuber yield, mean tuber weight, tuber number, shape, regularity, flesh colour, texture of the steamed flesh, fry colour, after-cooking blackening, sprout length after storage and overall dormancy. There were statistically significant differences between clones for all characters (P<0.001). Twelve of the clones were selected on the basis of high resistance, yield, tuber weight, regularity of shape and absence of after-cooking blackening. The value of resistant long-day-adapted diploid material for commercial breeding is discussed.     

Enzymatic blackening in potatoes: Influence of pH on dopachrome oxidation

The effects of pH on the nonenzymatic reactions of dopachrome leading to brown to black melanin formation were examined. At pH 5.0, the changes in dopachrome absorbance at 480 nm and formation of melanin were slow. After 7–8 hours the absorbance decreased to approximately one half of the original dopachrome solution. At pH 7.0 the changes were much more rapid. After 17 min the absorbance decreased by 0.15. An equivalent decrease in absorbance at pH 5.0 required almost 4 hours. At pH 7.0 the absorbance at 480 nm decreased to a minimum after 43 min and then increased for 4 hours when the absorbance of the pinkish grey solution was the same as the original orange dopachrome solution. Thus, the pH of any treatment used to inhibit enzymatic blackening is very important in determining the amount of discoloration finally obtained. A pH of 5.0 or lower which would inhibit both the nonenzymatic and enzymatic reactions in the blackening reaction would be most desirable unless flavor or texture problems arise.     

干旱区马铃薯测土配方施肥试验研究

合理施肥是发挥马铃薯生产潜力的重要措施之一,干旱区域其施肥技术尤为重要。通过试验,研究了马铃薯产量与氮、磷、钾最佳施用量之间的关系,建立了马铃薯产量(Y)与氮肥(N)、磷肥(P)、钾肥(K)之间的回归方程,得出安定区马铃薯每公顷最佳施氮量为(N)203.48kg,施磷量(P2O)5908.75kg,施钾量(K2O)217.27kg,此时马铃薯产量预报值为15941.55kg,最佳施肥量比例为1:4.47:1.07。试验结果为干旱区马铃薯测土配方施肥技术提供了理论依据。     

优良荷兰马铃薯品种的鉴定与选育研究

对１９９４年从荷兰ＡＧＲＩＣＯ公司引进的１６个马铃薯品种在不同生态区进行产量、加工品质等综合农艺性状的评价和鉴定,结果表明,荷兰品种在薯块性状方面表现突出,表皮光滑,芽眼极浅,并普遍抗Ｙ病毒。筛选出适合马铃薯薯条加工的品种“阿克瑞亚（ＡＧＲＩＡ）”,该品种薯块具有耐低温变甜的特性,于１９９８年通过了北京市农作物品种审定委员会的认定。另外,亦筛选出高产、鲜食的马铃薯品种红多（ＫＯＮＤＯＲ）,于１９９７年通过河北省张家口市农作物品种审定委员会认定。并对引种与育种的关系和加工品种选育鉴定应注意的问题进行了探讨。     

Behavioral responses of adult potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), to potato germplasm and transmission of Candidatus Liberibacter psyllaurous

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a major pest of potatoes that can cause yield loss by direct feeding on crop plants and by transmitting a bacterial pathogen, Candidatus Liberibacter psyllaurous (a.k.a. Candidatus Liberibacter solanacearum) associated with zebra chip disease of the crop. In recent years, there have been no studies regarding resistance of potato to the potato psyllid or the bacterial pathogen that the psyllid transmits. Thus, the objectives of this study were to determine the effects of potato germplasm on adult potato psyllid behavior and transmission of Ca. L. psyllaurous. A total of twenty-two potato (Solanum tuberosum L.) breeding clones and varieties were examined. Plant genotype significantly affected the occurrence and duration of psyllid probing, the duration of psyllid cleaning, resting and the amount of time psyllids spent off the potato leaflet as well as transmission of Ca. L. psyllaurous. For the potato genotypes in which there were significant decreases in transmission compared to controls, there was often an unclear relationship between the occurrences and duration of behaviors and subsequent bacterial transmission. We discuss the implications of our results for an integrated pest management program for the potato psyllid and Ca. L. psyllaurous control on potatoes.