Failure of systemic insecticide-nematicides to affect total glycoalkaloid content of harvested potato tubers in northern Florida

Tubers of Sebago, Pungo, and Wauseon cultivar potatoes were analyzed for total glycoalkaloid (TGA) content following treatment with systemic insecticide-nematicides in two experiments. The treatments were at plant applications of aldicarb, carbofuran, and phenamiphos, each applied at 3.4 kg ai/ha in-the-row; oxamyl, and ethoprop at 4.5 kg ai/ha in-the-row; and fensulfothion applied at 2.2 kg ai/ha in-the-row; and three 1.1 kg ai/ha overall foliar applications of oxamyl both alone and in combination with an at plant application of carbofuran at 4.5 kg ai/ha in-therow. None of the nematicide treatments significantly affected TGA content of potato tubers at harvest. Similarly, there were no significant differences in tuber TGA levels between the cultivars Pungo and Sebago in one experiment. In the other experiment Pungo and Wauseon tubers had significantly lower levels of TGA than Sebago. There were no cultivar X nematicide treatment interactions observed in either experiment.     

A comparison and modification of methods of total glycoalkaloid analysis

Total glycoalkaloid (TGA) content of potato tissues was determined using six methods of extraction. Blending 50 g tuber tissue for 8 minutes in a Waring Blendor with a 100 ml of 5% trichloroacetic acid (TCAA) in 75% methanol resulted in 99% extraction of TGA in relation to the soxhlet method of extraction. Extraction with 5% TCAA in 75% methanol reduced the analysis variation (standard error) by about one-half. TGA extraction with 5% TCAA and determination of TGA concentration with antimony trichloride can be completed in about 1/30 of the time required for the standard soxhlet method, thereby allowing for TGA analysis of a greater number of samples. The results indicate that extreme care should be taken in sample preparation and interpretation of the TGA level of potato tubers because of the wide variation of the TGA concentration present within a potato tuber.     

Ascorbic acid and glycoalkaloid content of Atlantic and Superior potato tubers as affected by supplemental irrigation and soil amendments

Atlantic and Superior potato (Solanum tuberosum L.) tubers were collected at harvest from two field experiments in Maine during 1993 and 1994. Tubers were analyzed for ascorbic acid (ASC) and total glycoalkaloid (TGA) concentration within one month of harvest and after 4 to 5 months of storage at 10 C. ASC concentration was significantly higher in Superior than Atlantic at harvest and after storage. TGA concentration was consistently higher in Atlantic than Superior. Irrigation tended to slightly reduce ASC and increase α-solanine concentrations when applied too late in the season for yield benefits. Storage decreased tuber ASC content, but no specific pattern was observed for TGA changes. Soil amendment programs using compost and manure (22 Mg ha^?1 potato compost + 45 Mg ha^?1 manure) did not dramatically affect tuber ASC or TGA concentrations. ASC content of the tubers declined dramatically in storage, but no consistent pattern was found for tuber TGA changes. We conclude that genotype, growing environment, and storage time play much stronger roles in determining tuber ASC and TGA levels than do irrigation and soil management programs. We observed a negative relationship between the average tuber size of the assayed samples and ASC concentration in fall samplings; however, this relationship was not observed from storage. Average tuber size and TGA content generally displayed a negative relationship.     

Effect of potato seed tuber glycoalkaloid content on subsequent infection byRhizoctonia solani

Since glycoalkaloids have been shown to have fungitoxic properties, it is important to know what impact this might have on potato plant breeding programs which select for low levels of total glycoalkaloids (TGA) in the tuber. Potato clones with TGA levels ranging between 1.6 and 32.8 mg/100 g fresh tissue were planted in two trials to evaluate the relationship between seed tuber TGA and incidence ofRhizoctonia solani infection in the developing plant. An inoculation procedure was followed in the greenhouse and field to establish uniform infection of potato seedlings. Plants were examined for lesion development on stems and stolons and assigned disease ratings. In the field, yield of malformed tubers was recorded and included in the overall disease ratings. The results reported herein indicate that TGA levels in the seed tuber are unrelated to the severity ofR. solani infection in the seedling.     

The joint action of nitrogen and nematicides onPratylenchus penetrans and potato yield

The joint action of nitrogen fertilizer and nematicides onPratylenchus penetrons and yield was investigated using three potato varieties (Superior, Onaway and Russet Burbank), three rates of nitrogen (84, 168 and 336 kg/ha), five edaphic pesticides (disulfoton, aldicarb, 1,3-D + MIC, carbofuran and thiofanox), and an insecticide spray to minimize the role of foliar feeding insects In 1977, disulfoton, aldicarb, and disulfoton plus 1,3-D + MIC significantly increased the yield of Superior at all nitrogen rates. The yield increases ranged from 37–56% for Superior, 15–35% for Onaway and 13–27% for Russet Burbank. Nitrogen had no detectable influence on yield. Population densities ofP. penetrans were significantly reduced by disulfoton plus 1,3-D + MIC and by aldicarb. Superior was most susceptible toP. penetrans, Onaway intermediate, and Russet Burbank moderately tolerant. Neither the potato variety or nitrogen significantly influenced the population densities ofP. penetrans In 1978 aldicarb, 1,3-D + MIC and thiofanox significantly increased yields of Superior at all nitrogen rates. Nitrogen also significantly increased yields, but only where aldicarb and 1,3-D + MIC were applied. Total yield was increased 12–14% and 17–23% by 1,3-D + MIC and aldicarb at 168 and 336 kg N/ha, respectively. Aldicarb, 1,3-D + MIC, and thiofanox appeared to increase tuber set, while nitrogen increased tuber size. Although all of the nematicides provided some control ofP. penetrans, aldicarb had the highest degree of efficacy and gave excellent season-long control     

Effects of drip irrigation regimes on potato tuber yield and quality under plastic mulch in arid Northwestern China

Field experiments were conducted to study the effects of drip irrigation regimes on potato (Solanum tuberosum L.) growth, tuber yield and quality, and water use efficiency (WUE) when grown under plastic mulch in an arid area of Northwestern China in 2008, 2009 and 2010. The 2008 experiment consisted of a drip irrigation check without plastic mulch and four different drip irrigation frequency treatments with plastic mulch: once every day, once every 2 days, once every 4 days, and once every 8 days. In 2009 and 2010 the drip check treatment without mulch was irrigated at −25 kPa soil matric potential (SMP) during three potato development stages and four different SMP drip irrigation strategies were compared during the potato development stages (using plastic mulch): S1 (−25 kPa SMP during the three development stages), S2 (−25 kPa SMP during tuber initiation and bulking and −35 kPa SMP during maturation), S3 (−25 kPa SMP during tuber initiation and maturation and −35 kPa SMP during bulking), S4 (−35 kPa SMP during the three development stages). Plastic mulch negatively affected tuber yield, WUE, and tuber quality. In the presence of plastic mulch, tuber yield, specific gravity, starch content, and vitamin C content seemed to be enhanced as the irrigation frequency increased, although the differences were not statistically significant. Irrigation frequency did not affect WUE for potato grown under plastic mulch. Analysis of plant height, tuber yield and WUE showed that a drip irrigation threshold of −35 kPa SMP led to obvious water stress for potato growth in this arid area. Under plastic mulch in 2010, S2 was the optimum drip irrigation regime because of the significantly higher yield than S3 and S4, the highest WUE and significantly firmer tubers than any of the other irrigation regimes tested.     

Effect of Harvest Date on PI2, Total Protein, TGA Content and Tuber Performance in Potato

Proteinase inhibitor 2 (PI2), isolated from potatoes is associated with the release of cholecystokinin (CCK), a satiety factor in humans. PI2 is the active ingredient of Slendesta® Potato Extract. The effect of harvest date on the levels of proteinase inhibitor 2 (PI2), total protein content and total glycoalkaloids (TGA) was studied in two potato (Solanum tuberosum L.) clonal lines. In addition, tuber specific gravity, tuber yield, and tuber size distribution were measured in response to harvest date. The two potato clonal lines designated as KI-PSt0018 and KI-PSt0034 were planted in a randomized complete block design with four replicates. Tubers were harvested at four different dates during the growing season; 4 weeks and 2 weeks to vine-kill; at vine-kill; and 2 weeks post vine-kill. Sample tubers from these four harvest dates and from 2 months of storage, post vine-kill stage were analyzed for PI2, total protein and TGA. Harvesting at different dates had a significant influence on most of the traits studied in both clonal lines. The two clonal lines responded differently to different harvest dates for all traits except PI2 and specific gravity. PI2 levels increased with maturity with the highest levels observed at full maturity in both clonal lines. The protein levels did not show any specific trend in either clonal line. TGA levels increased gradually in small increments with maturity in KI-PSt0018 but did not have a clear pattern in KI-PSt0034. Tuber yield and size increased with maturity of the crop in both clonal lines. Higher tuber yields were seen during final vine-kill and 2 weeks post vine-kill compared to the earlier stages of harvest in both clonal lines. Tuber specific gravity declined when tubers were left in the ground for 14 to 21 days after vine-kill in both clonal lines. This study indicated harvest of potato prior to vine-kill is not beneficial for the extraction of PI2 for use as functional food or dietary supplement ingredient.     

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.     

Sequential Path Analysis of Yield Components in Potato

In order to determine proper selection criteria for tuber yield in potato clones obtained from true potato seed (TPS) and to evaluate relationships between tuber yield and its components, an investigation was conducted using the five check cultivars Agria, Marfona, Draga, Agata, and Arinda, and 120 potato clones obtained from TPS. The study was conducted in an augmented randomized complete block design with three replications. Yield and its components were recorded. Correlation coefficient analysis showed that tuber yield had significant positive associations with number of tubers per plant, average weight per tuber (tuber size), plant height, diameter of main stem, and number of main and secondary stems per plant, whereas its correlation with tuber dry-matter concentration was significantly negative. Number of tubers per plant, tuber size, and plant height had significant standardized partial regression coefficients with very small tolerance and large variance inflation factor (VIF) values. These were considered as the first-order variables in sequential path analysis.     

不同施氮量对马铃薯的影响

本试验在固定Ｐ、Ｋ肥下，研究有无农家肥［Ｆ１（１５００ｋｇ／亩），Ｆ０（０ｋｇ／亩）］下不同施Ｎ量（０，２．５，５．０，７．５ｋｇ／亩）对马铃薯（品种疫不加）生长发育、矿物质营养吸收及产量品质的影响。结果表明：随施Ｎ量增加，叶面积、茎叶生长量、净同化率及块茎膨大速率也增加，Ｎ７．５处理明显优于Ｎ２．５及Ｎ０处理。施Ｎ增加了Ｎ的吸收，特别是Ｎ７．５处理，对Ｐ、Ｋ的影响不大，同时，也增加了Ｎ、Ｐ、Ｋ的转运率。有农家肥时增强了上述作用。最高产量施Ｎ为７．５ｋｇ／亩。Ｎ７．５Ｆ０处理鲜产为１６０４．９８ｋｇ／亩，Ｎ７．５Ｆ１处理为１６１３ｋｇ／亩。Ｆ０时Ｎ肥的产量效应方程为Ｙ＝１２９０．１４＋７４．３Ｘ，Ｆ１时效应方程为Ｙ＝２６１９．８７０＋７６．２３４Ｘ－２．４０Ｘ２（Ｘ从０→７．５ｋｇ／亩）。且随施Ｎ增加，淀粉含量有下降趋势，而淀粉产量逐渐增加，Ｎ５．０Ｆ１处理的淀粉产量为１７８．５１ｋｇ／亩。     

硼钼营养对马铃薯鲜薯产量及活性氧代谢的影响

研究了硼 (B)、钼 (Mo)营养 8种处理对马铃薯鲜薯产量和活性氧代谢的影响。结果证明 :B、Mo营养与马铃薯鲜薯产量及活性氧代谢有密切的关系 ,B、Mo营养具有明显的互作效应 ,当B浓度相同时 ,随着Mo浓度的提高 ,CAT活性与ASA含量也随之提高 ;当Mo浓度相同时 ,随着B浓度的提高 ,CAT活性与ASA含量也随之提高。适宜的B、Mo配施可提高SOD、POD、NR的活性 ,降低MDA含量与自动氧化速率 ,抑制膜脂过氧化作用 ,提高鲜薯产量。马铃薯鲜薯的生产能力与细胞保护酶 (SOD、POD、NR、CAT)活性呈极显著的正相关 ,与MDA含量呈显著的负相关     

Evaluation of potato varieties and selections for resistance to bacterial soft rot

Potato varieties and selections were evaluated for resistance to bacterial soft rot caused byErwinia carotovora subsp. carotovora and Erwinia carotovora subsp. atroseptica in mist chamber. A randomized complete block design with a single treatment and 3 replications was used in this study. Potato lines were inoculated with bacterial suspension (10 tubers / line) using the puncture inoculation method and incubated for 4 days in a mist chamber at 21 C and 100 % relative humidity in the dark. Although there were differences in incidence of soft rot and in amount of weight reduction, most of the potato lines were susceptible to tuber soft rot. Mean incidence (%) of soft rot ranged from 10 to 100%. Mean reduction of tuber weight (%) ranged from 0.13 to 16.43 %. Among the varieties and selections tested, AF 522-5 was the most resistant to tuber weight loss, while AF 1424-7 was most susceptible. There were also significant differences between years, and a variety by year interaction. Testing over a period of years is recommended. A significant correlation coefficient of soft rot incidence (%) and reduction of tuber weight (%) was obtained (r=0.65; P=0.05), indicating that incidence was a fair measure of soft rot potential. However, the greater variability in results for incidence make weight loss a better measure of soft rot reaction. There was a significant difference among varieties in the reduction of tuber weight when potato lines were inoculated either 1 month or 2 months after harvest, but the interaction of time by year prohibits a conclusion as to which time gives a better test reaction. Late maturing varieties had slightly less weight loss than earlier maturing varieties.     

Influence of chemical seed and soil treatments onVerticillium-induced yield reduction and tuber defects

Experiments were conducted in 1969 and 1970 to determine the influence of chemical treatments of seed pieces and soil on the development ofVerticillium wilt as measured by tuber yield increases and reduction in severity of tuber defects. The influence of storage onVerticillium-induced tuber defects was evaluated. Seed treatment chemicals tested included zinc ion maneb, maneb, maneb-chloroneb, Polyram, benomyl, and thiabendazole. Soil treatment chemicals included O-Diethyl (O-methyl-sulfinyl) phenyl phosphoro-thioate, disulfoton, phorate, carbofuran, aldicarb, ethyl 4 (methyl- thio)-m-tolyl isopropyl phosphor amidate, benomyl, and thiabendazole. Inoculated seed pieces and artificially infested plot areas were used the first year while the second year natural inoculum from a previous crop was the source of infection. Kennebec and Katahdin cultivars were tested in 1969 and Kennebec alone in 1970. Verticillium-induced yield reductions and tuber defects were more severe in all respects with Kennebec than with Katahdin. With Katahdin the only significant evidence of infection was stem end discoloration. Seed treatments, with the exception of benomyl or thiabendazole, which were erratically phytotoxic, resulted in consistent yield increases and reduction in pink eye severity. In 1969 seed treatment reduced stem end browning in Kennebec. Soil treatment with disulfoton, carbofuran, and aldicarb, both alone and in combination with seed treatments resulted in consistent yield increases with Kennebec. The seed piece and soil treatment combinations tested in 1970 appeared to have an additive effect on yield increase from combination treatments equivalent to the gain from soil treatment alone plus seed treatment alone. The nematicide soil treatment materials did not influence yield. Tuber stem-end browning and pink eye defects in Kennebec did not increase in severity over a five month storage period.     

Change in Some Glycoalkaloids of Potato under Different Storage Regimes

The potato (Solanum tuberosum L.) is an important food crop worldwide. Potato tubers can be stored to provide continuity of supply between production seasons, but it is important that they be stored under appropriate conditions as incorrect storage will result in deterioration in end user quality and may increase glycoalkaloid levels. We have investigated the effects of types of household storage on potato glycoalkaloid content (total glycoalkaloids [TGA]; α-solanine; α-chaconine) in Turkey. Tubers of potato cultivars (cvs.) Agria and Bettina were stored under four types of storage conditions (indirect sunlight for 10 h per day and dark storage for the remaining 14 h per day; storage under continuous fluorescent light; storage in constant darkness; storage in the dark in a refrigerator) for 56 days. Samples of tubers were taken at the beginning of the storage period and after 14, 28 and 56 days of storage for tuber glycoalkaloid measurement. Tubers stored in the three light environments showed an increase in glycoalkaloid levels; however, none of the cv. Agria tubers reached the critical level of 200 mg/kg tuber. On day 56 the TGA level of cv. Bettina tubers stored under fluorescent light reached 234.31 mg/kg.     

The effectiveness of using a minituber crop for selection of agronomic characters in potato breeding programmes

Summary Performance of 20 potato genotypes was studied for seven agronomic characters in crops raised from minitubers and normal seed tubers. Correlation coefficients were computed between minituber crop and normal seed crop in order to study the selection efficiency at minituber crop level. The performance of normal seed crop was significantly better than the minituber crop for various characters including tuber yield and its components. Correlation coefficients between minituber and normal seed crop were significant for various characters except number of stems and number of tubers. Highest correlation coefficient (r=0.86) was for tuber yield followed by average tuber weight (r=0.67) and number of nodes (r=0.63). The results suggest that selection for tuber yield can be practised at the minituber crop level in potato breeding programmes     

The influence of glycoalkaloids,chlorogenic acid and sugars on the susceptibility of potato tubers to wireworm

Summary Field experiments with four potato cultivars showed that there were significant differences in susceptibility to attack by wireworm,Agriotes obscurus. The two most susceptible cultivars had the lowest total glycoalkaloid (TGA) contents. Laboratory experiments with wireworms feeding on tuber slices demonstrated that regions characterized by a low sugar and a high glycoalkaloid concentration were avoided as feeding sites. Bio-assays with glycoalkaloids also showed that paper discs treated with a mixture of solanine and chaconine were avoided by wireworms. According to a forward stepwise regression analysis based on data from four cultivars and six regions of the tuber. TGA was the key factor in predicting larval feeding, accounting for 65% of the total variation. Differences in reducing sugar levels (fructose + glucose) explained an additional 13% of the variation. Differences in chlorogenic acid and sucrose levels added very little to the accuracy of the prediction.     

Metalaxyl and other fungicides for control ofPhytophthora infestans on potato in northwest Washington State

In northwest Washington State, fungicidal control of late blight caused byPhytophthora infestons was evaluated for three years. During 1977, a high rainfall year with supplemental sprinkler irrigations, all metalaxyl and chlorothalonil treatments reduced tuber rot at harvest, but only metalaxyl extended control of tuber rot after 4 months’ storage. During 1978, a high rainfall year, one application of metalaxyl sprayed over or dusted on potato seed pieces at planting or applied five times to foliage at 2 or 4 wk intervals gave excellent blight control equal to that with chlorothalonil applied to foliage every 2 wk. In 1979, a low rainfall year,P. infestons did not kill plants in untreated plots until October. Five applications of metalaxyl sprayed every 2 wk on foliage did not control foliage blight. However, metalaxyl reduced foliage blight when dusted on cut potato seed pieces. Mancozeb sprayed every 2 wk also gave excellent control. The possibility that metalaxyl applied to foliage is effective in late blight control only when washed into the soil by rainfall or irrigation for uptake by roots is discussed. Yields and percent U.S. No. 1 grade tubers were not significantly affected by any treatment in these 3-year trials.     

腐殖酸氮磷钾复合肥对马铃薯产量、商品率及淀粉含量的影响

腐殖酸氮磷钾复合肥单一施用或与尿素配合施用，马铃薯的商品率和淀粉含量均比对照显著或极显著提高．综合考虑，单一施用是最佳处理，在马铃薯生产中，可以推广使用这种肥料．     

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。     

马铃薯高世代无性系铁含量的稳定性及广义遗传力估算

人体中存在多种微量元素,其中铁元素含量最多,且缺铁性贫血已成为公共卫生问题.如果能通过遗传改良提高马铃薯块茎铁含量,将对人类健康大有帮助.试验目的是分析利用国外种质资源杂交选育的高世代马铃薯材料铁含量,评价铁含量的稳定性,并估算铁含量的广义遗传力.2017和2018年,把19份马铃薯高世代材料和2份对照品种('夏坡蒂'...