Tuber Maturity Research Articles

The Effect Irrigation Scheduling and Potassium Fertilization on Water Consumption of Potato (Solanum tuberosum L.) Under Modern Irrigation Systems

A field experiment was conducted in Yusufiya sub-district - Mahmudiya township/Baghdad governorate in silty loam texture soil during the spring season of 2020. The experiment included three treatments with three replicates, as the Randomized Complete Block Design (RCBD) was used according to the arrangement of the split design block. The treatments are in the irrigation system, which included surface drip irrigation (T1) and sprinkler irrigation (T2). Secondly, the Irrigation levels including the irrigation using 0.70 Pan Evaporation Fraction PEF (I1), irrigation using 1.00 PEF (I2), and irrigation using 1.30 PEF (I3). Coupled with, Potassium fertilization treatments that include (0.0 kg k ha-1 (K1), 150 kg k ha-1 (K2) and 300 kg k ha-1 (K3)). The results showed that the actual seasonal water consumption reached its peak at irrigation level I1, which reached 390.03 and 256.41 mm for the sprinkler and drip irrigation systems, respectively. However, the actual seasonal water consumption at irrigation level I2 was 373.92 and 255.63, and it was 353.82 and T255.15 mm at irrigation level I3 for the sprinkler and drip irrigation systems, respectively. The lowest values of the crop coefficient at the tuber maturity stage using the sprinkler irrigation system were 0.49, 0.46, and 0.44, and at the vegetative growth stage using the surface drip irrigation system by 0.37, 0.32, and 0.38 for irrigation levels I1, I2, and I3, respectively. Even though the greatest values were in the tuber Initiation and bulking stages, as they reached 0.86, 0.66, and 0.79 using the sprinkler irrigation system, while they reached 0.49, 0.54, and 0.51 using the surface drip irrigation system for I1, I2, and I3 levels, respectively. The highest water productivity for treatment I3K3 was 15.70 and 27.20 kg m-3 of sprinkler and surface drip irrigation systems, respectively. In contrast, the lowest water productivity was 8.73 and 17.72 kg m-3 for treatment I1K1 of sprinkler and surface drip irrigation systems, respectively. Whereas, the highest value of crop water use efficiency was 11.70 and 17.58 kg m-3 for I3K3 treatment of sprinkler and surface drip irrigation systems, respectively. Although, the lowest value of crop water use efficiency was 6.71 and 11.49 kg m-3 for I1K1 treatment of sprinkler and surface drip irrigation systems, respectively. Lastly, the highest yield was 44.87 Mg ha-1 at treatment T1I3K3.

Analysis of Optimum Growth Stages for Winter Crop Separability using Multi-Temporal NDVI Profiles in Vijapur Taluka, Gujarat State

The multi-date Remote sensing satellite data has shown its great potential in agricultural applications. The crop monitoring throughout its growing season requires up-to-date and timely information for better crop growth management. In the present study analysis of growth stages of different winter crops grown in Vijapur Taluka was carried for determining optimum growth period for crop separability using multi-temporal NDVI profiles. The multi-temporal Sentinel-2 multi-spectral data (spatial resolution 10-m) covering study area for the winter crop period from November-2018 to March-2019 was downloaded from https://earthexplorer.usgs.gov/. Ground Truth (GT) data on winter crops grown in different villages of Vijapur Taluka was collected at multiple locations coinciding with different growth stages of winter crops. The spectral behavior of wheat, cotton, potato, fennel and castor crops during active growth stages was studied and it was observed that the spectral response of these crops is quite distinct. The maximum spectral difference was observed in the NIR spectral band as compared to other visible spectral bands of Sentinel-2 multi-spectral data. However, wheat and potato have almost similar spectral response during the month of January when wheat was at flag leaf to flowering stage and potato was at maximum vegetative growth stage. This suggests that, single-date Sentinel-2 multispectral digital data of active vegetative growth stages of these two crops during the month of January is not appropriate and sufficient for unique discrimination of wheat and potato. Therefore, Normalized Difference Vegetation Index (NDVI) profiles of these major winter crops were generated to monitor crop growth stages where maximum spectral differences can be observed. The results of NDVI growth profiles indicated that, during second fortnight of February wheat was grain filling and grain-milk stage and potato was at maximum vegetative stage with tuber maturity and at the same time other crops namely cotton, castor and fennel were at the maturity stages, have quite distinct NDVI values. During this period major winter crops with different growth stages in this study area will have quite distinct spectral behaviour which indicates that the period of second fortnight of February is quite appropriate and unique for discriminating these winter crops using single date satellite data.

Effect of excessive nitrogen on levels of amino acids and sugars, and differential response to post-harvest cold storage in potato (Solanum tuberosum L.) tubers

Nitrogen (N) is an important nutrient for increased potato tuber yield. However, excessive N can decrease tuber quality. Furthermore, the impact of optimal and higher N levels of potato tuber metabolic profile at harvest and cold storage remains unclear. This study aimed to investigate the metabolic profiling of free amino acids and sugars in potato tubers affected by different nitrogen levels (optimal, ON; and excessive, EN) at harvest (AH) and cold storage (CS) (~4 °C, 4 weeks) through untargeted GC–TOF–MS, and targeted UHPLC–QqQ–MS. Carbohydrate content and vacuolar invertase activity (IV) were determined. Principal component analysis of metabolite data indicated a distinct separation between ON and EN treatments at harvest and cold storage. Multivariate data analysis revealed that sucrose, reducing sugars, and free asparagine were the most altered metabolites (VIP > 1 and P < 0.05), which were involved in starch and sucrose metabolism, and alanine, aspartate and glutamate metabolism. At harvest, the absolute contents of various free amino acids including asparagine were higher (by 1.3–1.5 fold) in the EN treatment than ON treatment, and this difference was maintained at 4-week cold storage. Under the EN treatment, tuber maturity was reduced, and sucrose accumulation was increased at harvest, while IV was increased after cold storage, reducing sugar also accumulated. These results highlighted the negative effects of EN on free amino acid and sugars metabolism in the post–harvest tubers and provided useful information for understanding the underpinning physiological mechanisms.

Radiation Interception, Conversion and Partitioning Efficiency in Potato Landraces: How Far Are We from the Optimum?

Crop efficiencies associated with intercepted radiation, conversion into biomass and allocation to edible organs are essential for yield improvement strategies that would enhance genetic properties to maximize carbon gain without increasing crop inputs. The production of 20 potato landraces—never studied before—was analyzed for radiation interception (), conversion () and partitioning () efficiencies. Additionally, other physiological traits related to senescence delay (normalized difference vegetation index (NDVI)), tuberization precocity (), photosynthetic performance and dry tuber yield per plant (TY) were also assessed. Vegetation reflectance was remotely acquired and the efficiencies estimated through a process-based model parameterized by a time-series of airborne imageries. The combination of and , closely associated with an early tuber maturity and a NDVI explained 39% of the variability grouping the most productive genotypes. TY was closely correlated to senescence delay (r = 0.74), indicating the usefulness of remote sensing methods for potato yield diversity characterization. About 89% of TY was explained by the first three principal components, associated mainly to , and , respectively. When comparing potato with other major crops, its is very close to the theoretical maximum. These findings suggest that there is room for improving and to enhance potato production.

Analysis of Tuber Maturity on Levels of Acrylamide in Selected Solanum Tuberosum Products (Chips and Crisps)

Analysis of Tuber Maturity on Levels of Acrylamide in Selected Solanum Tuberosum Products (Chips and Crisps)

DEVELOPMENT AND TESTING OF ARROWROOT (MARANTHA ARUNDINACEA L.) GRINDING MACHINE

An arrowroot grinding machine was developed and evaluated in terms of functional performance and cost effectiveness. The model consists of different component assembly parts such as transmission, rasper, crusher and base frame. It is powered by a 7.5 hp gasoline engine. Its salient features such as: 1) made of locally available food grade materials, 2) portable and 3) can be operated by a single person, give it the edge over other existing machines in attaining effective processing. The model has an overall cost of P65,000.00. The effects of different factors which include the machine speed, tuber size and tuber maturity on the response variables such as power requirement, processing time, machine capacity and efficiency (percent starch recovery) were observed. RSReg and Response Surface Methodology (RSM) were used to determine the effect of the treatment factors and optimum performance of the machine; respectively. Experimental runs using Box and Behnken design with three levelincomplete factorial designs were conducted. Results revealed that change on the levels of treatment factors significantly affect most of the response variables. Data obtained from the response variables mostly fit the linear and quadratic regression models. Results of evaluation revealed that the model is capable of grinding arrowroot tubers with average power consumption of 0.85 kW, processing time of 7.85 minutes, capacity of 46.6 kilograms per hour and efficiency (starch recovery) of 16.6%. Verification tests indicated that the actual values of responses were relatively close to the predicted values. Further, financial analysis showed that the machine was economically feasible for small scale farm arrowroot production with payback period of 0.343 years or 4 months and 3 days, break-even point of around 350 kg per year and benefit cost ratio of 1.96.

The effect of nitrogen fertilization on yield efficiency and quality of tubers potato varieties cultivated in an integrated production system

The aim of the research conducted in the years 2016 – 2018 was to perform the effect of nitrogen on the total yield and quality evaluation of edible and starch potato varieties harvested after tuber maturity, as well as to establish fertilization efficiency indices. The quality of tubers was expressed: yield structure, share of deformations, content of starch and nitrates (V), but the nitrogen utilization efficiency as agronomic efficiency (AE) and fertilizer recovery efficiency (FRE) in tubers. Two experimental factors were researched: nitrogen doses (0, 50,100, 150 kg·ha-1) and varieties (Impresja, Mazur, Otolia, Szyper and Widawa) tested under different weather conditions. The total yield fresh matter between nitrogen doses ranged from 42.8 to 53.7 t·ha-1 and for varieties from 42.1 (var. Szyper) to 54.8 t·ha-1 (var. Impresja). Increasing nitrogen doses caused an increase share in the yield structure big tubers (diameter above 60 mm), nitrates (V) and total nitrogen content and nitrogen uptake with tuber yield, but decrease starch content and nitrogen fertilization efficiency indicators. On the basis of quadratic function parameters, it was shown that the varieties of Impresja, Szyper and Otolia were characterized by greater requirements in relation to the optimal nitrogen dose than the varieties of Mazur and Widawa. More assessed features determined the weather conditions during the growing season than the factors studied: the nitrogen fertilization dose and the variety. In the year with the highest amount of rainfall in relation to the average of many years, the largest decrease was recorded: tuber yield, share of big tubers in the yield structure, nitrogen uptake and agronomic efficiency. Year with the most rainfall was characterized by the highest reduction the yield of tubers, share big tubers in the yield structure, nitrogen uptake and its agronomic efficiency.&#x0D;

Suberin deposition in potato periderm: a novel resistance mechanism against tuber greening.

Light-induced tuber greening is one of the most important quality defects of potato. Although varietal and maturity factors are known to affect greening resistance, physiological mechanisms of resistance are poorly understood. We proposed that physiological and biochemical factors within the tuber periderm provide resistance and hypothesised that resistance is primarily related to suberin content. We investigated differences in the tuber periderm between genotypes and tuber maturities that varied in greening propensity. We examined suberin and light-induced pigment accumulation, and phellem cell development and studied greening propensity in mutant and chemically treated tubers with enhanced suberisation. Resistance to greening was strongly linked to increased suberin in the periderm, which varied with variety and tuber maturity. Furthermore, greening was reduced in mutant and chemically treated tubers with enhanced suberisation. Increases in phellem cell layers and light-induced carotenoids and anthocyanins were identified as secondary resistance factors. Our work represents the first physiological mechanism of varietal and tuber maturity resistance to greening, expanding the known functionality of suberin and providing for the first time a biomarker that will aid producers and breeders in selection and improvement of potato varieties for greening resistance.

Yield, frying quality, plant vigor, and maturity of potato clones

ABSTRACT The objective of this research was to evaluate advanced potato clones for tuber yield, frying quality, plant vigor, and maturity, grown from minituber seeds, and to assess correlations between these traits. Eight advanced potato clones of Embrapa Potato Breeding Program (F11-09-03, F05-11-03, F54-11-06, F141-11-01, C2718-12-09, C2718-24-09, C2743-09-09, and CL308) and three commercial cultivars (Agata, Asterix and BRSIPR Bel) were evaluated. Experiments were carried out in autumn 2017, in Canoinhas-SC and Pelotas-RS. A randomized complete block design with four replicates was used. We used tuber seeds type IV (minibubers). We evaluated plant vigor, maturity, yield and number of marketable tubers, yield and number of total tubers, average tuber weight, specific gravity, and frying color. Individual and joint variance analyses revealed significant differences (p &lt;0.05) among genotypes for all traits at both locations. The GxE (genotype x environment) interaction was significant for all traits. For the two locations together, clones F05-11-03, C2718-12-09, C2718-24-09 and the control cultivar BRSIPR Bel showed higher marketable tuber yields. The first two clones also showed tubers with high average tuber weight. Clone F54-11-06 showed the later maturity at both locations. Regarding the frying quality characteristics, only clone F141-11-01 showed a pattern comparable to that of the control cultivar Asterix. Also, clones with higher plant vigor had higher tuber yield, but late maturity. Frying quality traits were not correlated between them and among other traits.

Linkage analysis and QTL mapping in a tetraploid russet mapping population of potato

BackgroundGenome-wide single nucleotide polymorphism (SNP) markers coupled with allele dosage information has emerged as a powerful tool for studying complex traits in cultivated autotetraploid potato (Solanum tuberosum L., 2n = 4× = 48). To date, this approach has been effectively applied to the identification of quantitative trait loci (QTLs) underlying highly heritable traits such as disease resistance, but largely unexplored for traits with complex patterns of inheritance.ResultsIn this study, an F1 tetraploid russet mapping population (162 individuals) was evaluated for multiple quantitative traits over two years and two locations to identify QTLs associated with tuber sugar concentration, processing quality, vine maturity, and other high-value agronomic traits. We report the linkage maps for the 12 potato chromosomes and the QTL location with corresponding genetic models and candidate SNPs explaining the highest phenotypic variation for tuber quality and maturity related traits. Significant QTLs for tuber glucose concentration and tuber fry color were detected on chromosomes 4, 5, 6, 10, and 11. Collectively, these QTLs explained between 24 and 46% of the total phenotypic variation for tuber glucose and fry color, respectively. The QTL on chromosome 10 was associated with apoplastic invertases, with ‘Premier Russet’ contributing the favorable allele for fry processing quality. On chromosome 5, minor-effect QTLs for tuber glucose concentration and fry color co-localized with various major-effect QTLs, including vine maturity, growth habit, tuber shape, early blight (Altenaria tenuis), and Verticillium wilt (Verticillium spp.).ConclusionsLinkage analysis and QTL mapping in a russet mapping population (A05141) using SNP dosage information successfully identified favorable alleles and candidate SNPs for resistance to the accumulation of tuber reducing sugars. These novel markers have a high potential for the improvement of tuber processing quality. Moreover, the discovery of different genetic models for traits with overlapping QTLs at the maturity locus clearly suggests an independent genetic control.

Crecimiento y contenido de azúcares de tubérculo de papa en cuatro estados de madurez en condiciones de invernadero

The sugar content in the potato tuber determines the optimum harvest time, the type of processing and its handling during storage. The aim of this study was to evaluate the growth and yield of four potato varieties under greenhouse conditions and to determine the soluble sugar content of this tuber at different maturity stages. For this, potatoes (5 ± 1 g) of four varieties were sampled at four maturity stages, from the beginning of tuberization to physiological maturity, in which the soluble sugar content was determined by high-performance liquid chromatography (HPLC). The Alpha variety had the longest growth cycle (1,230 degree days, P ≤ 0.05), while Mondial had the highest yield (380 g, P ≤ 0.05), 75, 31 and 31 % more than Vivaldi, Alpha and Atlantic, respectively, attributed to the highest average tuber weight (61 g, P ≤ 0.05). The highest content of sucrose, glucose and fructose (7.65, 2.22 and 0.37 mg·g-1, respectively) was recorded 21 days after the start of tuberization, quantities that decreased (P ≤ 0.05) during tuber development. Atlantic stands out with the lowest levels (P ≤ 0.05) of sucrose, glucose, fructose and total sugars in the different stages of tuber maturity. Average tuber weight was negatively correlated (P ≤ 0.05) with the contents of sucrose, reducing sugars (glucose and fructose) and total sugars.

Evaluation of Cassava (Manihot Esculenta crantz) Genotype for Yield and Yield Component, Tuber Bulking, Early Maturity in Cross River Basin Flood Plains, Itu, Akwa Ibom State, Nigeria

Field experiments was conducted in 2013 and 2014 at Cross River flood plains , Itu, Akwa Ibom State to assess the yield, yield components, early tuber bulking and maturity among cassava genotype and identify superior ones for the environment. Experiment was conducted at Itu Irrigation Erosion and Flood Control project farm of the Cross River Basin Development Authority Oku Iboku. A land area of 416m² was laid out in a Randomized Complete Block Design (RCBD) and replicated three times. Five cassava genotypes: NR 8082, TMS 01/1168, TMS 01/1412, TME 419 and a local cultivar (obubit okpo) constituted the treatments. Growth parameters studied were: plant height (cm), Number of branches, leaf area (cm), Number of leaf lobes, stem girth (cm) and length of petiole (cm). Also, Number, length (cm), and circumference of tubers and tuber yield per hectare (t/ha) were studied at 4,6,8,10 and 12 months after planting (MAP). Analysis of variance was conducted on all the characters and significant means separated with least significant difference (LSD) at 5% probability level. Plant height (cm), number of branches and leaf area (cm²) at harvest showed significant differences (p

Potato Vine Killing or Desiccation

Proper tuber maturity at harvest is an important factor in producing high-quality fresh-market potatoes. Tuber maturity is generally recognized as an important determinant of storage ability and cooking quality. Maturation can be artificially induced by killing the potato vines prior to harvest. This will benefit tuber appearance, limit tuber size, and improve tuber release from the vine. This revised 4-page fact sheet describes the importance of tuber maturation, potato vine killing timing and available methods, and how to determine when to vine kill and when to harvest after vine kill. Written by Lincoln Zotarelli, Steven Sargent, Peter Dittmar, and Mildred Makani, and published by the Horticultural Sciences Department, January 2016. HS925/HS181: Potato Vine Killing or Desiccation (ufl.edu)

Effect of ventilation strategy on storage quality indicators of processing potatoes with different maturity levels at harvest

Ventilation management and the tuber maturity at harvest are essential factors in maintaining potato quality during long-term storage. The aim of this study was to examine the effect of ventilation strategy on storage quality of potato tubers with three different maturity levels at harvest. Two potato cultivars, Saturna and Asterix, were stored in small-scale experimental stores and large-scale commercial stores. Both storage categories were ventilated by both low continuous air rates (natural ventilation) and intermittent high air rates (forced ventilation). The different maturity levels were obtained by a combination of pre-sprouting strategy, planting date and level of nitrogen fertilization of the seed tubers, where pre-sprouting, early planting date and low amount of nitrogen resulted in the most mature tubers. Storage quality parameters investigated during and after long-term storage (6months in small-scale and 4months in large-scale stores) included weight loss, respiration, dry matter, sucrose, glucose/fructose content and fry colour. In average over three years natural ventilation resulted in higher weight losses in small- and large-scale stores (1.36 and 3.93%), lower content of reducing sugars (glucose+fructose) in large-scale stores (2.35mgg−1) and lighter fry colour than did forced ventilation. Immature potatoes had higher weight losses (4.16%), higher respiration rates (1.68mgCO2kg−1h−1) and lower dry matter content (22.3–22.5%) than more mature potatoes. This study show that both maturity and ventilation strategy affects storage quality of potatoes as measured by weight loss, sugar content and fry colour.

Cloning, 3D modeling and expression analysis of three vacuolar invertase genes from cassava (Manihot Esculenta Crantz).

Vacuolar invertase is one of the key enzymes in sucrose metabolism that irreversibly catalyzes the hydrolysis of sucrose to glucose and fructose in plants. In this research, three vacuolar invertase genes, named MeVINV1-3, and with 653, 660 and 639 amino acids, respectively, were cloned from cassava. The motifs of NDPNG (β-fructosidase motif), RDP and WECVD, which are conserved and essential for catalytic activity in the vacuolar invertase family, were found in MeVINV1 and MeVINV2. Meanwhile, in MeVINV3, instead of NDPNG we found the motif NGPDG, in which the three amino acids GPD are different from those in other vacuolar invertases (DPN) that might result in MeVINV3 being an inactivated protein. The N-terminal leader sequence of MeVINVs contains a signal anchor, which is associated with the sorting of vacuolar invertase to vacuole. The overall predicted 3D structure of the MeVINVs consists of a five bladed β-propeller module at N-terminus domain, and forms a β-sandwich module at the C-terminus domain. The active site of the protein is situated in the β-propeller module. MeVINVs are classified in two subfamilies, α and β groups, in which α group members of MeVINV1 and 2 are highly expressed in reproductive organs and tuber roots (considered as sink organs), while β group members of MeVINV3 are highly expressed in leaves (source organs). All MeVINVs are highly expressed in leaves, while only MeVINV1 and 2 are highly expressed in tubers at cassava tuber maturity stage. Thus, MeVINV1 and 2 play an important role in sucrose unloading and starch accumulation, as well in buffering the pools of sucrose, hexoses and sugar phosphates in leaves, specifically at later stages of plant development.

Partial Study of Yam Tuber (&lt;em&gt;Dioscorea&lt;/em&gt; spp.) Parts during the Growth Period

Growing gradient into longitudinal axis of yam tuber was study through starch properties and nutritional composition of tuber parts (proximal, median and distal) during the tuberization. Two varieties of the complex D. cayenensis-rotundata (kangba and kponan) were used. Clarity, swelling and solubility, flow behavior and syneresis of starch and protein content, alcohol-soluble sugars of the flour were studies. The ash assessed by microanalysis. Starch clarity of tuber parts increased during the growth period. The proximal (56±2.06%) and median (54.5±1.09%) parts exhibited high clarity than the distal (48.2±2.56%) one. At earlier stage of tuberization, the viscosity ratio of tuber parts (var. Kponan) was weak. This indicates the possibility to use it as thickening agent in shearing sauce. Water loss decreased during the growth period for the three tuber parts. It was the same behavior for the swelling power. Concerning the nutritional composition of the flour, amount of protein did not influenced by the degree of tuber maturity. Alcohol-soluble sugars were higher at earlier stage of tuberization than at maturity of the tuber. Mineral content was appreciable at maturity than at beginning of the tuberization. The extent mineral according to their amount was: K, P, Mg and S. Starch properties such as clarity, syneresis and swelling were improved at maturity of the tuber. It was more for the proximal and median parts than the distal one. Yam tuber content a appreciable amount of protein and mineral at maturity.

Effect of Climate on Yam Tuberization in the Guinea Savanna Ecological Zone of Nigeria: The Case Study of Kwara State

The response of yam tuber development to its micro-climate was monitored at the National Centre for Agricultural Mechanization (NCAM) for two yam growing seasons. The micro climate data measured include air temperature, rainfall, number of rain days, relative humidity, soil temperature at intervals of 5cm, 20cm, 30cm and 40cm and soil moisture with depths at 0-15cm, 15-30cm and 30-45cm. Measurement of yam tuber circumference and length were taken on monthly basis from the period of tuber initiation (34 WAP) to period of tuber maturity (50 WAP) using thread and measuring tape. Monthly means of weather elements from research plot was calculated, grouped and summarized using descriptive statistics of mean and percentages. Dependency of yam tuber development on meteorological factors was examined through statistical analysis of correlation and regression. Based on this, the period of tuber development in Kwara State was identified and categorized. The growth in yam tuber responds positively more to rainfall frequency than rainfall amount. Again soil temperature at 5cm depth was identified to be more critical for efficient yam tuberization. Farmers in the study area are advised to improve on the materials used for mulching to increase yam yield.

Phenotypic analysis of tuber yield- and maturity-related traits in white yam (Dioscorea rotundata)

Inadequate yield potential of available varieties and their long growth periods are two of the factors limiting yam ( Dioscorea spp.) production. Identifying yield- and maturity-related traits and breeding for them will enhance production. Ten morphological/physiological traits: time of shoot emergence, time of tuber initiation, plant height, shoot dry weight, time of shoot senescence, tuber fresh weight (tuber yield), tuber number/plant, tuber parenchyma colour, tuber dry matter content and tuber dormancy period were assessed in eight accessions of D. rotundata (white Guinea yam) on the field in 2008 and 2009. Shoot dry weight and plant height were identified as the major tuber yield-related traits. Early field emergence and tuber initiation, short tuber dormancy period and low tuber dry matter content may also be related to tuber yield. High yielding accessions were low in tuber dry matter content. Moreover, early and late maturing accessions could be separated by time of attainment of uniform parenchyma colour within a tuber, length of tuber dormancy period and time of shoot senescence. Accessions were identified that may be used as parents for developing mapping populations for some of the traits assessed in the study. Key words: Dioscorea rotundata , tuber maturity, tuber dormancy, dry matter content, yield related traits, senescence.

Long-Term Cold Storage Suppress the Development of Tuber Necrosis Caused by PVYNTN

The aim of this work was to determine the influence of different storage temperatures and tuber maturity on development of tuber necrosis caused by Potato virus Y NTN . Infected tubers of the cultivar Igor of two different maturity groups and non-infected tubers were randomly distributed into 12 storage regimes. Control treatments were stored at constant temperatures of 4, 13 and 24°C. Tubers in the other nine treatments were stored at 4°C at the beginning of experiment and transferred to 24°C after 1 to 29 weeks after harvest. High storage temperatures enhanced the development of tuber necrosis. Prolongation of low temperature storage delayed the development of necrosis and reduced the number of tubers with necrosis. When tubers were stored at low temperature for 21 weeks or more, no necrosis developed after transfer to high temperature. We could not confirm the effect of maturity on development of necrosis caused by PVYNTN.

Vine-Kill Treatment and Harvest Date have Persistent Effects on Tuber Physiology

The quality of potato (Solanum tuberosum) tubers coming out of storage depends on the state of the tubers going into storage. Experiments determined the effects of vine-kill treatment and harvest date on the post-harvest physiology of potato tubers stored for up to 12 weeks. Potato cultivar Russet Burbank grown in central Wisconsin was harvested in late July when tubers were immature, in late August, and in early September after complete natural senescence of vines. Prior to the first two harvests, vines were either desiccated with diquat dibromide or were untreated. Data were collected at harvest and in storage for skin set, tuber respiration rate, and tuber sucrose, glucose, and fructose contents. Skin set at harvest was increased by use of the desiccant at the early harvest date, but not at the middle harvest date. Early harvest without vine kill resulted in elevated tuber bud-end glucose contents in storage. Early harvest with vine kill treatment resulted in increased rates of respiration in storage that persisted through December. Neither tuber sucrose nor glucose content 6 weeks after harvest was a good predictor of tuber glucose content 12 weeks after harvest. These data demonstrate that vine-kill treatment and tuber maturity at harvest have long-term effects on tuber quality.