Potato (Solanum tuberosum L.) yield response to simulated hail damage

Yield loss in potato damaged by hail is mainly caused by reduced leaf area and plant stand. A 2-year field experiment was conducted to investigate the effect of simulated hail damage on potato yield. The treatments were six levels of defoliation (control, 20, 40, 60, 80 and 100%) and five defoliation times (2, 5, 8, 11 and 14 weeks after emergence). The experiment was set up in a randomized block design with four replications, and the treatments were arranged as a factorial. From the perspective of yield loss, the most important time of defoliation, for mild and intense defoliation, respectively, were 8–11 and 5–11 weeks after emergence. The period between 5 and 8 weeks includes the stages of tuber initiation and tuber growth; the stages most sensitive to removal of aerial parts. Regardless of defoliation intensity, the production of small potatoes mostly occurred when defoliation occurred at 2 and 5 weeks. Plants were able to recover from any level of defoliation if it occurred at an early stage. In summary, yield reduction was little influenced by intensity of defoliation, but the timing of defoliation was evidently the most important factor.     

Effect of Xanthan Gum and CMC on the Structure and Texture of Corn Flour Pellets Expanded by Microwave Heating

Third‐generation snacks obtained by microwave expansion of glassy cereal pellets are often hard and nonuniform and need to be improved to become acceptable to the consumer. Gums such as carboxymethyl cellulose (CMC) and xanthan gum (XG) have the ability to improve the volume, structure, and texture of expanded cereal products, due to their effects on moisture retention and rheological properties. This study investigates the effect of 1% addition of CMC and XG on the structural and mechanical properties of samples obtained by microwave expansion of glassy corn pellets. Unexpanded, glassy pellets were obtained by extrusion and subsequent equilibration at a_w = 0.53 at room temperature. The equilibrated pellets were expanded by microwave heating. The addition of gums significantly improved the shape, structural and textural uniformity of the microwave‐expanded samples. These effects were attributed to the contribution of gums to the rheology and moisture sorption capacity of the matrix. It is our hypothesis that the extended hydrocolloid macromolecules interpenetrated the polymeric starch matrix and created a fine network of “holes” distributed relatively uniformly in the matrix, which served as additional nucleation sites for expansion. The conclusions of this study can be used in the design of high‐quality, fat‐free, third‐generation snacks.     

黑龙江省马铃薯气候生产力特征及区划

利用黑龙江省81个气象站1975-2004年30 a的逐日气象资料及相应插值的网格同期逐日气象资料,采用WOFOST作物生长模型,模拟并分析了马铃薯气候生产力的空间分布特征,同时分析了各地气候生产力影响因素及分布特征;利用气候生产力的距平百分率、变异系数及与气候生产力密切相关的有关生育期的4个气候因子(平均气温、气温日较差、日平均日照时数、降水量),采用动态聚类分析方法,将黑龙江省马铃薯可能种植区初步划分为9类气候栽培区,为充分利用当地气候资源发展马铃薯生产提供参考。     

SSR标记的彩色马铃薯遗传多样性分析及指纹图谱构建

彩色马铃薯(指块茎的皮或肉为红、蓝、紫、橙色等)近年来日益为育种工作者所关注,很多彩色马铃薯品种(系)从形态学上难以鉴定是否为同一基因型,给育种工作带来诸多不便。本研究利用SSR标记对50份彩色马铃薯(Solanum tuberosumL.)材料进行了遗传多样性分析及指纹图谱构建。研究筛选出56对马铃薯SSR引物,对50份材料的基因组DNA进行PCR扩增,共检测出236个等位位点,其中多态性位点230个,多态性比率达97.46%。分析显示,基因型间遗传相似性系数在0.50~1.00之间。UPGMA聚类分析表明,在相似系数0.63处可将全部材料分为3大类。利用5对核心引物构建了50份供试材料的指纹图谱,并证明其属于44个基因型的,为彩色马铃薯资源鉴定和利用提供了依据。     

Preparation of High‐Quality Protein‐Based Extruded Pellets Expanded by Microwave Oven

The aim of this work was to study the effects of extrusion barrel temperature (75–140°C) and feed moisture (16–30%) on the production of third‐generation snacks expanded by microwave heating. A blend of potato starch (50%), quality protein maize (QPM) (35%), and soybean meal (SM) (15%) was used in the preparation of the snacks. A laboratory single extruder with a 1.5 × 20.0 × 100 mm die‐nozzle and a central composite routable experimental design were used. Expansion index (EI) and bulk density (BD) were measured in expanded pellets, viscosity at 83°C (V₈₃), thermal properties, and relative crystallinity were measured in extruded pellets. EI increased and BD decreased when the barrel temperature was increased, while the feed moisture effect was not significant. V₈₃ increased when feed moisture increased. Extrusion modified the crystalline structures of the pellets and the X‐ray data suggests the formation of new structures, probably due to the development of amylose‐lipid complexes. The maximum expansion of pellets was found at barrel temperatures of 123–140°C, and feed moisture of 24.5–30%. It is possible to obtain a functional third‐generation snack with good expansion characteristics using a microwave oven, and this snack has health benefits due to the addition of QPM and SM.     

Systematic Measurement Methods for the Determination of the SPAD Values of Maize (Zea mays L.) Canopy and Potato (Solanum tuberosum L.)

Based on Soil Plant Analysis Development (SPAD) values, nitrogen (N) deficiency, nutrient need, and the effect of fertilizer treatments on crop conditions can be quickly estimated, but the method of SPAD measurement significantly affects the accuracy of estimation. In field experiments near Debrecen, Hungary, we measured the reliability and accuracy of SPAD measurements in maize and potato populations using a Minolta SPAD-502 meter (Minolta, Tokyo, Japan). The aim of our study was to determine which SPAD measurement methods are capable of detecting small differences in the SPAD values. During the examination of maize ear leaves, we determined the distribution of SPAD values along the leaf blade and then identified single- and multipoint measurement methods. By comparing the results of the measurement methods we established that the single-point-based measurements are less suitable for the determination of the average SPAD value of the leaf blade than the multipoint-based measurements. Also, we showed that the increase in the number of measurement points does not influence the accuracy of the measurement in the case of systematic measurement methods based on the distribution of SPAD values. Thus we recommend five-point measurements to obtain the average SPAD values of the ear leaves: the tip of the leaf blade and at one quarter and one half of the leaf blade from the base on both the right and left sides. From the measurements conducted in potato, we showed that the SPAD values change at every foliar level and that the measurements carried out on the middle foliar level provide the closest correlation with the average SPAD values of the leaf canopy. Based on these results, we recommend making measurements at different foliar levels or on the middle foliar level to determine the average SPAD value of the potato leaf canopy.     

RNA干涉对马铃薯内源酸性转化酶活性的影响

酸性转化酶是植物体内降解蔗糖为还原糖（葡萄糖、果糖）的关键酶,而还原糖在马铃薯（Solanum tuberosum L.）低温贮藏中的快速积累是影响油炸加工品质的重要因素。为了实现对马铃薯块茎低温糖化的品质改良,本研究利用所克隆的酸性转化酶基因构建了RNA干涉载体,并转化马铃薯品种N2。经PCR、Northern鉴定,酸性转化酶基因的干涉片段已经成功导入马铃薯植株中。对干涉转基因株系的试管苗和试管薯的酸性转化酶活性进行测定,结果显示,植株的酸性转化酶的活性平均下降69.8%（Ni-1除外）,最大降幅为78%（Ni-4）,而试管薯的酶活性最大降幅为68%。与反义RNA的表现较好的转基因株系进行比较,RNA干涉对酶活的调节作用与之相当。研究结果表明,RNA干涉对马铃薯内源酸性转化酶活性的调节作用显著,这种转录表达的调控技术对马铃薯低温糖化改良具有良好的应用前景。     

Simulating the development of field grown potato (Solanum tuberosum L.)

The simulation of developmental stages is an important part of many crop simulation models because photoassimilates partitioning to different organs varies with plant developmental stage. Developmental models can also help in pest control and fertilizer application programs, in breeding strategies, and in crop harvest programming. There are several models for simulating potato (Solanum tuberosum L.) development. These models have assumptions that are open to criticism, such as the thermal time approach to describe the effect of temperature on potato development, they assume a constant set of cardinal temperatures throughout the crop cycle and they do not take into account the effect of photoperiod on potato development. These assumptions have disadvantages, because they are not completely realistic from a biological viewpoint. The Wang and Engel (WE) model [Wang, E., Engel, T., 1998. Simulation of phenological development of wheat crops. Agric. Syst. 58, 1–24.] seems appropriate to overcome the disadvantages of current potato models, but it has been used to simulate development in annual crops where the reproductive organs are above ground, not in potato. The objective of this study was to adapt the WE model to simulate development of field grown potato. A series of field experiments was carried out at Santa Maria, Rio Grande do Sul State, Brazil, with 15 planting dates: nine in the year of 2003 and six in the year of 2004. The WE model was superior to the thermal time approach for predicting the date of major developmental stages (tuber initiation, beginning of plant senescence, and harvest), with an average root mean square error (RMSE) of 10.4 days, which corresponds to a 28–45% decrease in the RMSE compared with the thermal time methods. Model predictions with the WE model were better for earlier (tuber initiation, RMSE = 3.7 days) than for later developmental stages (harvest, RMSE = 14.0 days).     

马铃薯田线虫病害发生及防治

近些年马铃薯土传病害发生严重,除了真菌、细菌等病原物引起的病害外,线虫病成为威胁马铃薯生产的又一大病害.危害马铃薯的植物寄生线虫主要有马铃薯腐烂茎线虫(Ditylenchus destructor)、鳞球茎线虫(Ditylenchus dipsaci)、马铃薯孢囊线虫(马铃薯白线虫(Globodera rostochi...     

Glycoalkaloid development during greening of fresh market potatoes (Solanum tuberosum L.)

Chlorophyll and glycoalkaloid synthesis in potato (Solanum tuberosum L.) tubers occur in direct response to light. The two processes are concurrent, but independent. Color photographic indices to subjectively grade fresh market potatoes for the extent of greening were developed under lighting conditions consistent with those of retail markets. Total glycoalkaloid (TGA) and chlorophyll accumulation for four cultivars were determined over the respective greening scales, thus calibrating the scales for TGA content. On average, TGA concentrations in complete longitudinal sections of tubers (flesh samples) were highest in Dark Red Norland followed by Russet Norkotah, Yukon Gold, and White Rose. TGA concentrations of flesh samples of White Rose and Yukon Gold tubers were somewhat variable and did not increase in direct proportion to greening level and chlorophyll content, particularly at higher levels of greening. TGA concentrations in Dark Red Norland and Russet Norkotah tubers were highly correlated (P < or = 0.001) with greening level and chlorophyll concentrations. When averaged over greening levels, skin samples contained 3.4- to 6.8-fold higher concentrations of TGAs than flesh samples, depending on the cultivar. The TGA concentration in periderm samples ranged from 37 to 160 mg/100 g of dry wt. Regardless of greening level, concentrations of TGAs in the flesh samples (including attached periderm) remained within limits presumed safe for human consumption. Discrimination of greened tubers on the basis of perceived glycoalkaloid toxicity is likely unfounded for the cultivars and greening levels studied.     

Light and temperature modulated expolinear growth model for potato (Solanum tuberosum L.)

Expolinear growth equations are robust and simple models for the early and middle stages of crop growth. Those proposed by Greenwood and by Monteith were compared for potato (Solanum tuberosum L.) crop biomass in well-managed fields in the Central Wisconsin Sand Plain, and the Monteith equation found preferable. A time-derivative form of the Monteith equation was coupled to daily solar radiation and air temperature. Solar radiation was linked to daily maximum absolute growth through light use efficiency, and daily maximum relative growth rate was made a function of temperature by assuming a doubling of biological processes with every 10 °C increase (Q₁₀=2). The modified model predicted dynamic dry matter accumulation variation from year to year, and showed improved prediction of potato growth until senescence.     

Effect of selenate supplementation on glycoalkaloid content of potato (Solanum tuberosum L.)

Potatoes (Solanum tuberosum L.) supplemented with increasing amounts of sodium selenate were analyzed for glycoalkaloid (GA) content. GAs were extracted with 5% acetic acid from freeze-dried tubers of two potato cultivars, Satu and Sini, harvested 10 weeks after planting as immature. The GAs alpha-solanine and alpha-chaconine were quantified by reverse-phase high-performance liquid chromatography (RP-HPLC) with diode array detection. Two independent experiments were performed. In the first experiment, the total GA concentration +/- standard error of the tubers ranged between 105 +/- 9 and 124 +/- 10 mg kg(-1) fresh weight in Satu and between 194 +/- 26 and 228 +/- 10 mg kg(-1) fresh weight in Sini. The ratio of alpha-solanine to alpha-chaconine was 0.2 in Satu and 0.5-0.6 in Sini. In the second experiment, the total GA concentration +/- standard error was 75 +/- 4 to 96 +/- 11 mg kg(-1) fresh weight, and the ratio of alpha-solanine to alpha-chaconine was 0.3-0.4 in Satu. A high sodium selenate supplementation (0.9 mg of Se kg(-1) quartz sand) slightly decreased the GA content in Satu, but this decrease was not statistically significant. Furthermore, at this addition level the Se concentration increased to a very high level of 20 microg g(-1) dry weight, which cannot be recommended for human consumption. In both experiments, the Se concentration in tubers increased with increasing sodium selenate application levels. Our results show that acceptable application levels of selenate did not have an effect on the GA concentration in immature potato tubers.     

Different pre-sprouting methods for early tuber harvest in potato (Solanum tuberosum L.)

Abstract

Earlier harvest of potatoes (Solanum tuberosum L.) can be achieved by different treatments of the seed tubers. This can be important, for example, in areas with a short growing season and in organic farming. In a pot experiment, different pre-sprouting methods were evaluated for four cultivars. The experiment consisted of (a) untreated seed tubers stored at 4 °C until planting, (b) traditional pre-sprouted tubers (P) and (c) pre-sprouted tubers with stimulation of adventitious root formation (PR). Pre-sprouted seed tubers have earlier and faster tuber formation, but often lower yield than non pre-sprouted tubers if there is no restriction of the growing season. The PR method developed here, where tubers were sprayed with water to stimulate adventitious root formation and give faster development and tuber initiation than conventional pre-sprouting, can be of value when the growing season is restricted or if early harvest is important. Initial emergence of the pre-sprouted potatoes was monitored in two pot experiments. Emergence was faster for the pre-sprouted treatments compared with the control, but there were no significant differences between the two pre-sprouting methods. At harvest, the pre-sprouted treatments gave higher yield than the control for all growing periods, methods and cultivars, although the differences were not significant for every combination. The cultivars Matilda, Cicero, Ovatio and Superb seemed to respond more positively in terms of yield to PR treatments than cv. Ditta. The new method for stimulating adventitious root formation developed here will substantially help growers to achieve earlier harvests.     

Umami compounds are a determinant of the flavor of potato (Solanum tuberosum L.)

Vegetable flavor is an important factor in consumer choice but a trait that is difficult to assess quantitatively. The purpose of this study was to assess the levels of the major umami compounds in boiled potato tubers, in cultivars previously assessed for sensory quality. The free levels of the major umami amino acids, glutamate and aspartate, and the 5'-nucleotides, GMP and AMP, were measured in potato samples during the cooking process. Tubers were sampled at several time points during the growing season. The levels of both glutamate and 5'-nucleotides were significantly higher in mature tubers of two Solanum phureja cultivars compared with two Solanum tuberosum cultivars. The equivalent umami concentration was calculated for five cultivars, and there were strong positive correlations with flavor attributes and acceptability scores from a trained evaluation panel, suggesting that umami is an important component of potato flavor.     

Solanidine hydrolytic extraction and separation from the potato (Solanum tuberosum L.) vines by using solid-liquid-liquid systems

Solanidine is a steroidal aglycon of potato (Solanum tuberosum L.) glycoalkaloids and a very important precursor for the synthesis of hormones and some pharmacologically active compounds. Glycoalkaloids are hydrolyzed by mineral acid, yielding solanidine. This paper deals with the kinetics of solanidine hydrolytic extraction in different solid-liquid-liquid systems. The dried and milled potato (S. tuberosum L.) vines were used as a source of glycoalkaloids and as the solid phase. The solutions of hydrochloric acid in 2 and 10% (w/v) aqueous acetic acid, in 50% (volume) aqueous methanol, and in 50% (volume) aqueous ethanol were first liquid phase, and the medium for glycoalkaloid extraction from potato vines and their hydrolysis to solanidine. The chloroform, trichloroethylene, or carbon tetrachloride were the second, organic, liquid phase and the medium for solanidine extraction. This procedure combines three different processes: extraction of glycoalkaloids from potato vines, their hydrolysis to solanidine, and the extraction of solanidine, in a single step. The term hydrolytic extraction of solanidine was used for these processes. The purpose of the paper was to choose an optimal solid-liquid-liquid system for solanidine extraction and to define the procedure for its isolation from the organic liquid phase. The best degree of solanidine hydrolytic extraction (DHE) of more than 98% was achieved when 10% (w/v) hydrochloric acid in 50% (volume) methanol were the first liquid phase and chloroform was the second liquid phase, after 90 min. The yield of solanidine (q(S)) under these conditions is calculated to be 0.24 g/100 g of potato vines. Approximately 78% of the maximal possible yield of solanidine was isolated from chlorofom liquid phase. The IR and MS spectra of isolated solanidine were recorded.     

Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients

Potato tubers were evaluated as a source of antioxidants and minerals for the human diet. A genetically diverse sample of Solanum tuberosum L. cultivars native to the Andes of South America was obtained from a collection of nearly 1000 genotypes using microsatellite markers. This size-manageable collection of 74 landraces, representing at best the genetic diversity among potato germplasm, was analyzed for iron, zinc, calcium, total phenolic, total carotenoid, and total vitamin C contents. The hydrophilic antioxidant capacity of each genotype was also measured using the oxygen radical absorbance capacity (ORAC) assay. The iron content ranged from 29.87 to 157.96 microg g-1 of dry weight (DW), the zinc content from 12.6 to 28.83 microg g-1 of DW, and the calcium content from 271.09 to 1092.93 microg g-1 of DW. Total phenolic content varied between 1.12 and 12.37 mg of gallic acid equiv g-1 of DW, total carotenoid content between 2.83 and 36.21 microg g-1 of DW, and total vitamin C content between 217.70 and 689.47 microg g-1 of DW. The range of hydrophilic ORAC values was 28.25-250.67 micromol of Trolox equiv g-1 of DW. The hydrophilic antioxidant capacity and the total phenolic content were highly and positively correlated (r = 0.91). A strong relationship between iron and calcium contents was also found (r = 0.67). Principal component analysis on the studied nutritional contents of the core collection revealed that most potato genotypes were balanced in terms of antioxidant and mineral contents, but some of them could be distinguished by their high level in distinct micronutrients. Correlations between the micronutrient contents observed in the sample and the genetic distances assessed by microsatellites were weakly significant. However, this study demonstrated the wide variability of health-promoting micronutrient levels within the native potato germplasm as well as the significant contribution that distinct potato tubers may impart to the intake in dietary antioxidants, zinc, and iron.     

Isolation and partial characterization of thermostable isoperoxidases from potato (Solanum tuberosum L.) tuber sprouts

Peroxidases (POD; EC 1.11.1.7) can cross-link cell wall polymers and may have an impact on the final textural quality of potato tubers. Because heat treatments are important during processing, the thermal properties of isoPODs from soluble and ionically and covalently bound fractions were studied from both potato tubers and sprouts. For both tissues, the ionically bound fraction was the most thermostable; approximately 20% of POD activity remained after a heat treatment of 10 min at 90 degrees C (for sprouts). The temperature profile of the ionically bound sprout fraction appeared to be nonlinear and suggested the presence of a very thermostable POD, which still showed activity after a heat treatment at 100 degrees C. Visualization by using isoelectric focusing confirmed the occurrence of a thermostable isoPOD with an IEP of 9.5, which displayed regeneration of activity after heat inactivation. This cationic POD was further purified by chromatography techniques, and by SDS-PAGE its molecular mass was estimated at 38 kDa.     

Boron stress,oxidative damage and antioxidant protection in potato cultivars (Solanum tuberosum L.)

Six potato cultivars grown in Turkey in boron-prone areas and differing in their tolerance towards high boron were studied to reveal whether boron causes oxidative stress. To assess stress level, chlorophyll fluorescence and growth parameters were measured. Oxidative damage was assessed as malondialdehyde level, and antioxidant protection was evaluated as ascorbate (AA), dehydroascorbate, reduced glutathione (GSH) and oxidized glutathione amounts and superoxide dismutase, catalase, ascorbate peroxidase (APX) and glutathione reductase (GR) activities. High boron stress affected photosynthesis negatively in a threshold-dependent manner and inhibited growth. No pronounced changes in oxidation of lipids occurred in any cultivar. Activation of APX suggested the involvement of an ascorbic acid–reduced glutathione cycle in the protection against oxidative stress caused by high boron. Efficient work of this antioxidant system was probably hindered by boron complexation with NAD(P)⁺/NAD(P)H and resulted in the inhibition of GR and a decrease in AA and GSH. Hence, oxidative stress associated with high boron is a secondary component of boron toxicity which arises from metabolic changes caused by boron interference with major metabolites. Potato cultivars tolerate excess boron stress well and show damage only in very high boron concentrations. The potato cvs best suited for high boron soils/breeding purposes are cvs Van Gogh and Agria.

Abbreviations: AA: ascorbic acid; APX: ascorbate peroxidase; CAT: catalase; DHA: dehydroascorbic acid; DHAR: dehydroascorbate reductase; DTNB: 5; 5′-dithiobis-2-nitrobenzoic acid; DTT: dithiotreitol; F_v/F_m: photosynthetic efficiency at the dark-adapted state; GR: glutathione reductase; GSH: reduced glutathione; GSSG: oxidized glutathione; MDA: malondialdehyde; ROS: reactive oxygen species; SOD: superoxide dismutase; TCA: trichloroacetic acid     

Wounding stress increases the phenolic content and antioxidant capacity of purple-flesh potatoes (Solanum tuberosum L.)

Several abiotic stresses, including ethylene, methyl jasmonate, temperature, light, and wounding, were tested for their ability to induce accumulation of phenolic compounds and antioxidant capacity in purple-flesh potatoes (cv. All Blue). Results indicated that temperature, ethylene, methyl jasmonate, and light treatments did not significantly affect the accumulation of phenolic compounds compared to control samples. Only tubers with low initial anthocyanin levels treated with methyl jasmonate showed approximately 60% anthocyanin accumulation. Wounding induced the accumulation of phenolics compounds and an increase of PAL-activity in sliced tissue compared to the control. Total phenolics increased approximately 60% with a parallel 85% increase in antioxidant capacity. These results show that selection of appropriate abiotic stresses can enhance the nutritional and functional value of potatoes.     

Influence of storage upon light-induced chlorogenic acid accumulation in potato tubers (Solanum tuberosum L.)

The influence of 2 weeks and 3 months of dark storage upon light-induced chlorogenic acid accumulation within tuber tissue of four potato cultivars and upon 5-, 4-, and 3-caffeoylquinic acid concentrations within cv. King Edward was determined. Storage period significantly affected (P < 0.05) the magnitude of the light-induced chlorogenic acid response with accumulation rates 3-4 times higher in tubers exposed to light after 2 weeks compared with those placed under light after 3 months. Comparison of chlorogenic acid concentrations in controls after 2 and 3 months of dark storage indicated that tuber chlorogenic concentrations decline during prolonged cold store at 5 degrees C. Rates of accumulation in response to light were cultivar-dependent with cv. Fianna the most light-sensitive and cv. Maris Piper relatively light-insensitive. In virtually all cases exposure to sodium and fluorescent light promoted higher rates of accumulation than did exposure to high-pressure mercury light sources. Chlorogenic acid values steadily increased over 15 days of illumination with, in the majority of cases, no indication of cessation. Light exposure increased 5-, 4-, and 3-caffeoylquinic acid accumulation rates in cv. King Edward. Irrespective of storage period and light source, ratios of 5-:4-:3-caffeoylquinic acid were ca. 85:15:0 at day 0 and 52:42:6 by day 15.