Inheritance of tuber greening under light exposure in diploid potatoes

Low tendency to tuber greening under light exposure is a desirable trait for marketing and processing potatoes. Knowledge of the genetic basis of this trait is limited. During two consecutive years tuber greening after 2-week light exposure was evaluated on 17 unselected diploid potato families obtained between parents with varying tuber-greening tendencies. Parents of these families and standard cultivars were evaluated at the same time. External and depth of tuber greening were examined after tubers were exposed to 2 weeks of light in the greenhouse followed by storage at 10 C, 4 C, and after reconditioning at 18 C. Families, storage conditions, and years significantly influenced tuber greening. Distribution of greening indicated it would be possible to select individuals with very low tuber-greening tendency. Generally, external tuber greening was more intense than depth of greening. External tuber greening increased during storage while depth of tuber greening decreased. A significant maternal effect on external tuber greening was found in one of the three sets of reciprocal crosses after storage at 4 C. Both general and specific combining abilities were important in the inheritance of tuber greening. The correlations between external and depth of tuber greening in most families were significant and relatively high. The results indicated that genotypes with low tendency to tuber greening can be selected in diploid families.     

Effect of Packaging Material on Shelf Life and Quality of Ware Potato Tubers Stored at Ambient Tropical Temperatures

The effect of seven packaging materials (transparent perforated and non-perforated high-density polyethylene (HDPE) bags, black perforated and non-perforated low-density polyethylene (LDPE) bags, nylon gunny sacks, khaki bags and net bags) on post-harvest quality of tubers from three potato cultivars was evaluated. Data were collected on time and percentage of sprouting, weight loss rates and percentage tubers with greening and rotting. Packaging significantly reduced weight loss and rate of tuber greening but increased the rate of sprouting and decay incidences. Non-perforated PE bags were the most effective in reducing weight losses, recording losses of 0.7 to 0.9% after 32 days in storage while unpackaged tubers had weight losses of 11 to 12%. Tuber rotting was highest (60 to 66% of the tubers) in non-perforated PE bags. Greening was faster in non-packaged tubers recording 55 to 100% after 2 weeks in storage and showed high cultivar differences, but did not occur in black bags, whether perforated or non-perforated. Sprouting was complete by week 3 in all tubers packaged in non-perforated HDPE bags irrespective of cultivar. Although the non-perforated HDPE bag packaging prevented weight loss, its positive effect was counteracted by the high incidence of rotting and sprouting. Amongst the different materials evaluated, perforated low-density black PE bags were the best method for ware potato packaging due to low sprouting, reduced weight loss, low rate of tuber greening and reduced rate of tuber decay compared to other packaging materials. The study also indicated that the interaction between cultivars, packaging and storage period also affected shelf life of ware potatoes under ambient tropical conditions.     

氮素形态与马铃薯品质的关系

在田间条件下研究了不同形态氮素对马铃薯块茎硝酸盐含量、淀粉、蛋白质及还原糖含量的影响。结果表明,马铃薯块茎内硝酸盐含量从块茎形成期到成熟收获期是逐渐降低的。使用铵态氮肥并加硝化抑制剂双氰胺可以显著地抑制马铃薯块茎硝酸盐的积累;与硝酸盐含量变化相似,从块茎形成期到收获期蛋白质含量也逐渐降低,不同氮素形态处理对马铃薯块茎内蛋白质含量的影响无显著差异;铵态氮添加双氰胺处理可降低块茎还原糖含量。虽然马铃薯被认为是喜硝作物,但本研究表明,不同氮素形态处理不仅没有造成马铃薯产量的显著差异,而且块茎内淀粉含量也无显著差异。     

The genetic basis for tuber greening in 24-chromosome potatoes

Greening of potato (Solarium tuberosum L.) tubers is often a problem in retail markets. An experiment was performed to study the mode of inheritance of tuber greening in 24-chromosome potatoes. Tuber greening was determined to be quantitatively inherited. Genetic and environmental variance components were calculated. Tuber greening inheritance is due to additive and epistatic effects. Epistatic effects accounted for 59% of the genetic variance. No dominance or maternal effects were observed. Narrow sense heritability was 0.27 and broad sense heritability was 0.66 after location, block, and genotype by environment interactions were removed. Broad sense heritability for tuber greening is large enough to permit effective selection against tuber greening in potato breeding programs when epistasis can be fixed.     

Relationship Between Tuber Storage Proteins and Tuber Powdery Scab Resistance in Potato

The potato genotypes (Solanum tuberosum L.) with russet tuber skin are generally resistant to powdery scab (Spongospora subterranea f.sp. subterranea or Sss). Lipoxygenase (LOX; EC 1.13.11.12) and patatin are two key storage proteins that are known to offer resistance to several diseases and insects. The objective of this study was to find out the relationship of these proteins in stored tubers with potato tuber powdery scab resistance, especially in russet skinned potatoes. An evaluation of potato germplasm with different tuber characteristics in a greenhouse environment over several years (2006–’11) suggests that russet skinned tuber genotypes (Mesa Russet, Centennial Russet and Russet Nugget) with negligible tuber disease severity index (DSI) and 100 % marketability were resistant to powdery scab. Higher physiological levels of LOX protein (on a dry weight basis) were negatively correlated with tuber DSI and positively correlated with tuber russet skin. Tuber total protein and patatin-lipase levels did not have a significant relationship with tuber powdery scab resistance. The proposed role of LOX protein in suberin- and/or non-suberin-mediated mechanisms of powdery scab resistance in russet skinned tubers are discussed here. The physiological levels of LOX protein can be considered as a useful marker for powdery scab resistance in potato breeding programs.     

The Impact of Retail Light Source on Greening of Russet Burbank Potato Tubers

The use of accent lighting in retail stores has focused illumination on potatoes for greater consumer awareness. Unfortunately, this directed light on displayed potatoes may impact the rate or level of tuber greening. The objective of this study was to evaluate the influence of various retail accent light sources on greening and quality of illuminated tubers. Two separate experiments exposed ‘Russet Burbank’ potato tubers to fiber optic, ceramic metal halide, fluorescent, fluorescent with filter lighting (experiment 1) and fiber optic, halogen, and fluorescent lighting (experiment 2). In each experiment, tubers were exposed to a consistent light intensity (1390 lx in experiment 1 and 1300 lx in experiment 2) in addition to a dark control. Tubers were illuminated for 22 h per day at an ambient room temperature of 22 C. Six randomly selected tubers were evaluated for level of greening, chlorophyll concentration, and weight loss at day 0, 2, 4, 7, and 9. Total glycoalkaloid content was analyzed at days 0 and 9. In experiment 1, the fiber optic and fluorescent illuminated tubers showed significantly lower chlorophyll content compared to the ceramic metal halide light source. There was no significant difference in chlorophyll level or greening rating between the fluorescent light source and fluorescent with filter. In experiment 2, the fiber optic illuminated tubers had lower chlorophyll content and less visual greening compared to the halogen illuminated tubers. Total glycoalkaloids were not significantly impacted by light source. The use of fiber optic lighting or a combination of fiber optic lighting with standard fluorescent lighting would retard the progression of greening in the retail store yet potentially highlight the commodity for consumer eye-appeal.     

Seed Potato Performance after Storage in Light at Elevated Temperatures

In regions with short growth seasons, it is of great importance to use potato (Solanum tuberosum L.) seed tubers with a high growth vigour and a short growth cycle. Such qualities may be obtained by treatments advancing the physiological age of the seed tubers. In this study, we have exposed tubers from four cultivars to various combinations of temperature and light conditions (green-sprouting) for 3–7 months in controlled climate. Subsequent sprout quality, seed tuber health and performance were studied in laboratory, greenhouse and field trials. Satisfactory short, sturdy and leafy sprouts were produced even after 7 months storage at 15 °C under light exposure. An assay of black scurf (Rhizoctonia solani) on the tuber skin showed that light exposure significantly reduced the occurrence compared with dark-stored tubers, while the average effect of storage temperatures was insignificant. In general, green-sprouting advanced emergence and plant growth by 1–2 weeks, and showed early tuber initiation and growth, compared to untreated material. Yields, 107 days after planting in the field trial, did not deviate significantly from untreated tubers. However, plant development at harvest was in accordance with general responses to physiological ageing of potato seed tubers, i.e. still tall and immature plants from untreated tubers, and short and mature plants from aged tubers. Results demonstrated the possibility of successful long-term storage of potato seed tubers in light at elevated temperatures and a potential for earlier harvests and higher early yields from such treatments.     

Carbon Disulphide (CS<Subscript>2</Subscript>) Promotes Sprouting and Affects the Metabolism of Harvested Minitubers Grown from True Potato Seed

Chemical agents may be used to overcome dormancy in potato tubers so as to permit early planting. In this paper, the effect of carbon disulphide on sprouting and related metabolic processes in potato tubers grown from true potato seed (TPS) was investigated. Carbon disulphide was applied to potato tubers derived from TPS, at a rate of 20 ml m^?3 container volume for 72 h. It accelerated tuber sprouting and increased tuber weight loss. It also caused an increase in the respiration rate, as well as ethylene emission from the tubers during the first 6 days after treatment. The respiration rate of carbon disulphide-treated tubers remained at a higher level than that of untreated controls for 35 days after treatment. In addition, carbon disulphide increased the concentrations of the soluble sugars sucrose and fructose, but not glucose, in the tuber tissues (buds, parenchyma). These findings suggest that carbon disulphide releases potato minitubers from dormancy and that dormancy breakage is associated with changes in tuber metabolism prior to the visible sprouting.     

马铃薯不同种收期块茎作种的生物效应

用春种夏收和夏播秋收块茎作种,比春种秋收块茎作种的L_1代植株叶面积指数高、衰老晚、光合效率高,田间病株率减少56％,Y病毒带毒株率减少50％和97.5％,块茎增产6.9％和18.2％。夏播秋收块茎作种,表现了更高的优势。     

Electrolyte leakage of aging potato tubers and its relationship with sprouting capacity

Summary With advancing physiological age of potato tubers an increase in electrolyte leakage from tuber tissue was observed for various seed lots. This increase was most marked after tubers exhibited sprout growth and corresponded with a decline in tuber water content. Leakage increased minimally with storage time when sprouting was prevented or limited by either dormancy, low storage temperature, or frequent desprouting. Sprouting capacity of tubers increased to a maximum and then declined with storage time. This decline coincided with the increase in electrolyte leakage, suggesting that membrane integrity was one determinant in vigour of seed potato tubers. The pattern of electrolytes leaking from tuber tissue could be described by a function composed of a saturable and a linear component, suggesting two different sources contributing to the leakage. The saturable component, expected to reflect membrane integrity, was most responsive to aging treatments. H/LA Paper No. 93-13. Department of Horticulture and Landscape Architecture, Project No. 1984. College of Agriculture and Home Economics Research Center, Washington State University. This work was supported in part by grant funding from the Washington State Potato Commission.     

Effects of Foliar and Tuber Sprout Suppressants on Storage of Ware Potatoes under Tropical Conditions

Potato (Solanum tuberosum L.) is an important source of dietary carbohydrate and cash income generation for farmers in the tropical highlands of Kenya. The feasibility for cold storage at the farm level is limited due to the high costs of maintaining such a facility and there is limited data on the long-term post-harvest storage and quality of tubers of tropical-adapted cultivars. Application of sprout suppressants to control premature sprouting of ware potato is an attractive proposition. The objectives of this study were to evaluate the efficacy of pre-harvest foliar applications of paclobutrazol (PBZ) and ethephon for sprout suppression on ware potato tubers in storage. Post-harvest spray applications of Isopropyl N-(3-chlorophenyl carbamate) chloropropham (CIPC) and 1,4-dimethylnaphthalene (DMN) on tubers as fog was also evaluated. Potato cultivars had varying levels of tuber dormancy. The tubers were stored at ambient temperature (23 C) and evaluated weekly for 24 weeks for percent of tubers sprouting, length of longest sprouts, tuber weight loss and assessed for dormancy for 24 weeks. Paclobutrazol prolonged tuber dormancy by 21–31 days and reduced tuber weight loss. Ethephon treatment had no effect on dormancy and tuber weight loss. Potato tubers treated with CIPC had greater sprout control than the other treatments in storage. Tuber response to DMN treatment varied among the three potato cultivars evaluated. The findings from this study imply that PBZ is effective in prolonging potato tuber dormancy for short-term basis at 23 C, while CIPC applied on tubers was effective for long term storage. Optimization of post-harvest potato storage can improve food security in the highland tropics.     

Auswirkungen des wiederholten mechanischen Entkeimens auf den Substanzverlust und die Qualität von Kartoffelknollen

The influence of a continued mechanical desprouting of potato tubers on weight loss and tuber quality was investigated in comparison with tuber irradiation (Cs 137), IPC/CIPC powder application, and the untreated control. Mechanical desprouting of tubers resulted in minimum weight loss, but it caused increased sugar content, rotting and internal sprouting. To give consumers an alternative for the conventional sprout prevention methods, tubers of varieties with a natural deep dormancy, and potato storage in low temperature should be preferred.     

马铃薯磷素的吸收、积累和分配规律

磷元素在马铃薯植株体内的流动性较大,磷营养水平与块茎膨大密切相关,块茎是磷素的最终贮存库。在块茎增长初期,叶片、地上茎和块茎中的磷素浓度均为一生中的最高值,此时是马铃薯对磷需求最多的时期,块茎形成后,则大量的磷(P2O5)向块茎转移。马铃薯对磷素(P2O5)吸收速率较低。在整个生育期内吸收速率呈单峰曲线变化,峰值出现在块茎增长期。     

A comparison of variability in storage behaviour of seed tubers from true potato seed and clonal tubers

Summary The tuber-to-tuber variability in storage behaviour of seed tubers from true potato seed was compared with that in clonal seed tubers after storage in the dark, in diffused light, or in diffused light with a single desprouting. The variability was estimated by calculating standard deviations of length, number and weight of sprouts, and tuber weight loss. After dark storage, the variability of these variables was greater in seed tubers from true potato seed than in clonal seed tubers. After storage in diffused light with a single desprouting, the variability of number, length and weight of sprouts of seed tubers from true seed was not statistically different from that observed in clonal seed tubers. All storage treatments resulted in a greater variability of tuber weight loss in seed tubers from true potato seed than in clonal tubers.     

Physiological Age Research during the Second Half of the Twentieth Century

As in other crops, yield and quality in the potato is determined by the genotype × environment interaction; limited by seed, crop, and storage management; and reduced by weeds, pests, and diseases. Within the limiting factors, seed tuber quality is crucial, both in low- and high-input crops. If poor seed tubers are used in low-input crops, only low yields can be expected. If poor seed tubers are used in high-input crops, the crops will not take proper advantage of other inputs, such as water, fertilizers, and pesticides applied. At present, physical aspects, such as shape and presence of wounds, seed tuber size, health, and physiological age, are the main components of seed quality, impacting seed vigour. Physiological age is defined as the physiological status of a seed tuber at any time, determined by genotype, chronological age, and environmental conditions from tuber initiation until new plant emergence. This minireview summarizes the physiological age assessment methods and the effects of crop and storage environment and management on physiological age and future crop performance. Possible tactics to reverse physiological age effects are also discussed. More research is still needed to develop a reliable and predictable indicator or index which can relate physiological age to yielding potential.     

Non-wound-induced suberization of tuber parenchyma cells: A physiological response to the wilt disease pathogenVerticillium dahliae

Verticillium spp. wilt pathogens enter the root and eventually penetrate xylem vessels of the plant where they can spread into the vascular tissue of the potato tuber. Infected tuber vessel elements often become discolored creating a serious internal tuber quality defect that prevents sale of raw product to its primary market. Despite the costly losses and disease issues created by these infections, the physiological responses to colonization of tuber vessel elements are poorly described, and a model system to study these responses in the laboratory has not been developed. The objectives of this research were to develop such a model system by determining if tuber vessel elements could be infiltrated withVerticillium spp. in a laboratory setting and if a detectable physiological response could be elicited and identified. Results demonstrated that tuber vessel elements in the model system could be infiltrated and that infiltration ofVerticillium dahliae Kleb. conidia into these vessel elements induced a suberization response on the walls of neighboring parenchyma cells. However, the walls of the infiltrated tuber vessel elements did not suberize. A similar suberization response was found in tubers that had been naturally infected byVerticillium dahliae in the field. The suberization response was histochemically determined by assessing the accumulation of suberin poly(aliphatics) and poly(phenolics). This process of internal suberization of tuber parenchyma cells occurred without induction by a wound signal. Consequently, the suberization signal was derived by introduction of the plant-pathogen into the tuber vessel elements. This simple model system provides a versatile tool to investigate the physiological responses of potato tuber to colonization of vessel elements. This is believed to be the first report for such a physiological response toVerticillium spp. in potato tuber.     

Overexpression of a Maize SPS Gene Improves Yield Characters of Potato under Field Conditions

Abstract

We analyzed the yield characters of field-grown transgenic potato plants (Solanum tuberosum) carrying a maize gene for sucrose-phosphate synthase (SPS), the key enzyme in sucrose synthesis. The SPS activity in the leaves of transgenic plants (line Ag1203) was 2 times that of the control (cv. May Queen). There was no difference in the photosynthetic CO₂ uptake rates between Ag1203 and May Queen plants, and the leaf starch content of Ag1203 was lower. These observations indicate that the introduction of a foreign SPS gene improved the supply of photosynthate from source (leaves) to sink (tubers). Additionally, leaf senescence of the transgenic potato plants was delayed relative to that of May Queen. The average tuber weight and total yield of Ag1203 plants were at least 20% higher, and the tuber sucrose content, which is related to eating quality, was also higher. Increased translocation of photosynthate and longer period of photosynthetic activity in the leaves may have increased the yield of Ag1203. These results suggest that introduction of the SPS gene improved the yield characters and quality of potato tubers under field conditions.     

The distributions of tuber sizes in droughted and irrigated crops of potato. II. Relation between size and weight of tubers and the variability of tuber-size distributions

Summary Tubers from six cultivars of potato grown in irrigated and droughted conditions were examined to show whether observed differences in grade distributions were simple consequences of differences in yield or were the results of changes in tuber shape or in the relative variability (Rv=σ/μ) of the distributions. Differences in tuber shape, indicated by the relations between tuber size (mm) and weight, were statistically significant but were insufficient to cause measurable changes in the grade distributions. There was a range of values of Rv but drought had no statistically significant effect on Rv and may only affect it by influencing the numbers of tubers set. The main effect of drought on the distribution of tuber sizes was through its effect on total yield and hence on mean tuber size. Yield and number of tubers define a unique tuber-size distribution regardless of the soil moisture stress experienced by the crop.     

湖南冬闲田马铃薯氮吸收分配规律研究

试验采用“3414”设计方案,分析冬闲田马铃薯在不同肥料水平下氮肥吸收分配规律。结果表明：马铃薯地上部全氮含量在全生育期间其动态变化呈现为苗期低,块茎形成期高,而在块茎成熟期缓陧下降的趋势,且在整个生育期内,氮素浓度的变化表现为地上部〉块茎;块茎中氮的含量均在块茎形成期最高,块茎成熟期下降。     

Screening tuber-bearingSolanum (potato) germplasm for efficient accumulation of tuber calcium

Resistance to several pathological and physiological tuber defects has been correlated with calcium level in the peel. In this study, a representative sample of potato species (including cultivated), was grown in the greenhouse. Plants were watered with low and high calcium solutions, and the resulting tubers analyzed. Thus, potato germplasm was screened for ability to accumulate tuber calcium when a control level of calcium is available, and ability to respond when higher levels are supplied. Some wild species significantly exceeded cultivated materials in one or both of these measures. Such species may provide a resource for breeding varieties which are more efficient calcium accumulators.