Sugar Beet Storage Research Articles

Improving the Storage of Sugar Beet by Polymeric Coverage Containing Phase Change Material

The aim of this experiment was to study the sugar and weight losses and non-sugar impurities of sugar beet during the storage by coverage containing phase change material (PCM). The combination of six coverage types and two storage intervals of 20 and 40 days was arranged in a greenhouse with temperature ranging from 8.5 to 24.5 °C and relative humidity between 47 and 80 %, and paraffin was used as PCM. The polyethylene coverages containing 0, 7 and 14 % paraffin with and without lamination were utilized. The results showed that during the course of 40 days, weight and sugar losses of sugar beet in samples without coverage were 10 and 6.5 times higher than the sample with coverage containing 14 % paraffin (P < 0.05). After 40 days of storage, the amount of K, Na and non-protein nitrogen increased 56, 50 and 65 %, respectively, in sugar beets without coverage as compared to sugar beets covered with 7 % paraffin containing film, laminated film containing 14 % paraffin and 7 % paraffin containing film, respectively (P < 0.05). The lowest degree days between covered samples was found in sugar beets were placed inside of coverage containing 14 % paraffin which was significant (P < 0.05). This shows that the technical quality of sugar beet depends on the rate at which dehydration, sugar loss and non-sugar impurities are minimized. Based on this, covering of sugar beet with polymeric film containing paraffin can be recommended.

Taxonomic analysis of the microbial community in stored sugar beets using high-throughput sequencing of different marker genes.

Post-harvest colonization of sugar beets accompanied by rot development is a serious problem due to sugar losses and negative impact on processing quality. Studies on the microbial community associated with rot development and factors shaping their structure are missing. Therefore, high-throughput sequencing was applied to describe the influence of environment, plant genotype and storage temperature (8°C and 20°C) on three different communities in stored sugar beets, namely fungi (internal transcribed spacers 1 and 2), Fusarium spp. (elongation factor-1α gene fragment) and oomycetes (internal transcribed spacers 1). The composition of the fungal community changed during storage mostly influenced by the storage temperature followed by a weak environmental effect. Botrytis cinerea was the prevalent species at 8°C whereas members of the fungal genera Fusarium and Penicillium became dominant at 20°C. This shift was independent of the plant genotype. Species richness within the genus Fusarium also increased during storage at both temperatures whereas the oomycetes community did not change. Moreover, oomycetes species were absent after storage at 20°C. The results of the present study clearly show that rot development during sugar beet storage is associated with pathogens well known as causal agents of post-harvest diseases in many other crops.

Influence of Harvest Timing, Fungicides, and Beet necrotic yellow vein virus on Sugar Beet Storage

Root rots in sugar beet storage can lead to multimillion dollar losses because of reduced sucrose recovery. Thus, studies were conducted to establish additional fungicide treatments for sugar beet storage and a greater understanding of the fungi involved in the sugar beet storage rot complex in Idaho. A water control treatment and three fungicides (Mertect [product at 0.065 ml/kg of roots; 42.3% thiabendazole {vol/vol}], Propulse [product at 0.049 ml/kg of roots; 17.4% fluopyram and 17.4% prothioconazole {vol/vol}], and Stadium [product at 0.13 ml/kg of roots; 12.51% azoxystrobin, 12.51% fludioxonil, and 9.76% difenoconozole {vol/vol}]) were investigated for the ability to control fungal rots of sugar beet roots held up to 148 days in storage during the 2012 and 2013 storage seasons. At the end of September into October, roots were harvested weekly for 5 weeks from each of two sugar beet fields in Idaho, treated with the appropriate fungicide, and placed on top of a commercial indoor sugar beet storage pile until early February. Differences (P < 0.0001 to 0.0150) among fungicide treatments were evident. Propulse- and Stadium-treated roots had 84 to 100% less fungal growth versus the control roots, whereas fungal growth on Mertect-treated roots was not different from the control roots in 7 of 12 comparisons for roots harvested each of the first 3 weeks in both years of this study. The Propulse- and Stadium-treated roots also reduced (P < 0.0001 to 0.0146; based on weeks 1, 3, and 4 in 2012 and weeks 1, 3, 4, and 5 in 2013) sucrose loss by 14 to 46% versus the control roots, whereas roots treated with Mertect did not change sucrose loss compared with the control roots in 7 of 10 evaluations. The predominant fungi isolated from symptomatic roots were an Athelia-like sp., Botrytis cinerea, Penicillium spp., and Phoma betae. If Propulse and Stadium are labeled for use on sugar beet in storage, these fungicides should be considered for root rot control in commercial sugar beet storage and on roots held for vernalization for seed production of this biennial plant species.

Effects of free air CO2 enrichment on root growth of barley, sugar beet and wheat grown in a rotation under different nitrogen supply

Elevated atmospheric CO2 concentrations [CO2] are known to change plant growth by stimulation of C3 photosynthesis and by reduction of transpiration of both C3 and C4 crops. In comparison to the information on above ground plant responses only limited knowledge exists on the response of root growth of arable crops to elevated [CO2] which is particularly true for temperate crop species under real field conditions. A free air CO2 enrichment (FACE) study (550ppm at daylight hours) was carried out in a crop rotation of winter barley, sugar beet and winter wheat repeated twice in the course of six years on a sandy loam soil at Braunschweig, Northern Germany. Winter barley and sugar beet were included for the first time in a FACE study. A possible interaction with restricted nitrogen (N) supply was studied by fertilizing the CO2 treatment plots with adequate and 50% of adequate N supply. Fine root samples were taken in the plough layer and below at 3–4 sampling dates during the vegetation period and root dry matter (excluding sugar beet storage root), shoot root ratio, root length density, specific root length and root tissue composition (CN ratio) were determined. Main effects of elevated [CO2] on the investigated variables were slightly significant. Significant CO2 effects were observed in interaction with the sampling date. In most cases elevated [CO2] increased root dry matter early in the vegetation period with a maximum growth stimulation of up to 54% as compared to ambient [CO2]. Concomitantly, root length densities were increased in both winter wheat and sugar beet. For winter barley also a significant decrease in root dry weight and significant increase of shoot root ratio was detected at final harvest while such an effect was not significant for sugar beet. Specific root length as an indicator of root morphology was mainly influenced by crop species. As a result, there was no consistent overall effect of elevated [CO2] on biomass partitioning in this study as changes in shoot root ratio only occurred at specific sampling dates indicating a similar stimulation of roots and above-ground biomass due to elevated [CO2]. Nitrogen supply did not alter the effect of elevated [CO2] on any of the root variables apart from CN ratios. A significant increase of root CN ratios in wheat and sugar beet was observed under elevated [CO2], but this effect was much smaller than the effect of N supply.

Postharvest salicylic acid treatment reduces storage rots in water-stressed but not unstressed sugarbeet roots

Exogenous application of salicylic acid (SA) reduces storage rots in a number of postharvest crops. SA's ability to protect sugarbeet (Beta vulgaris L.) taproots from common storage rot pathogens, however, is unknown. To determine the potential of SA to reduce storage losses caused by three common causal organisms of sugarbeet storage rot, freshly harvested roots were treated with 0.01, 0.1, 1.0 or 10mM SA, inoculated with Botrytis cinerea, Penicillium claviforme, or Phoma betae, and evaluated for the severity of rot symptoms after incubation at 20°C and 90% relative humidity. Roots were obtained from plants that received sufficient water or were water-stressed prior to harvest. Roots from water-stressed plants were included since water-stress increases sugarbeet root susceptibility to storage rot and SA mitigates drought effects in other plant species. SA at concentrations of 0.01–10mM had no effect on the severity of storage rot caused by B. cinerea, P. claviforme, or P. betae in roots from plants that received sufficient water prior to harvest. However, SA at these same concentrations reduced the severity of rot symptoms for all three pathogens in roots from plants that were water stressed before harvest. For water-stressed roots, all concentrations of SA produced statistically equivalent reductions in the weight of rotted tissue for each pathogen, and on average, SA reduced rot severity due to B. cinerea, P. claviforme, and P. betae by 54, 45, and 58%, respectively. SA reduced rot from all three pathogens by reducing lesion size, but did not affect the incidence of infection. The ability of SA to reduce rot severity in water-stressed roots, but not in roots that received sufficient water before harvest suggests that SA alleviated the negative impact of water stress but did not directly protect sugarbeet roots against storage rots.

Jasmonic acid does not increase oxidative defense mechanisms or common defense-related enzymes in postharvest sugarbeet roots

Jasmonic acid (JA) treatment significantly reduces rot due to several sugarbeet (Beta vulgaris L.) storage pathogens. However, the mechanisms by which JA protects postharvest sugarbeet roots from disease are unknown. In other plant species and organs, alterations in antioxidant defense mechanisms and elevations in common pathogenesis-related defense enzymes have been implicated in jasmonate-induced disease resistance. To investigate whether these mechanisms are involved in JA-induced disease resistance in stored sugarbeet roots, the activities of several reactive oxygen species (ROS)-scavenging and pathogenesis-related defense enzymes and the total concentration of antioxidant compounds were determined in harvested sugarbeet roots in the 60 d following treatment with JA. ROS-scavenging and pathogenesis-related defense enzymes and the concentration of antioxidant compounds were largely unaffected by JA as JA-treated roots exhibited small declines in superoxide dismutase (SOD) and chitinase activities, and were generally unaltered in ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), β-1,3-glucanase (β-Gluc), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities or antioxidant compounds concentration. The lack of increase in enzyme activities or metabolites related to defense against oxidative stress or pathogens suggests that JA-induced disease resistance in postharvest sugarbeet roots does not arise from a direct increase in any of the ROS-scavenging and defense-related enzymes examined, or the concentration of total antioxidant compounds. However, ROS-scavenging enzymes and pathogenesis-related defense enzymes were affected by storage duration with POD, SOD, β-Gluc, chitinase, and PPO activities elevated and APX and CAT activities reduced in roots stored for 10 d or more. Storage-related changes in activities of ROS-scavenging enzymes and defense-related enzymes provide further evidence that these enzymes are uninvolved in sugarbeet root disease resistance during storage since many of these enzymes increased in activity after prolonged storage when disease resistance generally declines.

Sugar beet (Beta vulgaris L.) storage quality in large outdoor piles is impacted by pile management but not by nitrogen fertilizer or cultivar

Van Eerd, L. L., Congreves, K. A. and Zandstra, J. W. 2012. Sugar beet (Beta vulgarisL.) storage quality in large outdoor piles is impacted by pile management but not by nitrogen fertilizer or cultivar. Can. J. Plant Sci. 92: 129–139. Even though storage results in lower sucrose recovery from sugar beets, physical constraints dictate that a significant proportion of the sugar beet crop can be stored up to 120 d before processing. From 2006 to 2010, N fertilization (0–220 kg N ha–1), sugar beet cultivar, and pile management method were independently evaluated to determine their effects on sugar beet storability in large outdoor piles. At harvest, five representative sugar beet samples from the N and cultivar field trials were placed in a large outdoor storage pile. Sugar beet quality assessments were taken at harvest and three times over the storage season. On the last retrieval date only, sugar beet samples were retrieved from piles managed via the length- vs. end-removal method. Although there were differences among N treatments and cultivars in sugar beet quality at harvest, there were no storage date by N treatment or storage date by cultivar interactions for any parameters measured indicating that N fertilization or cultivar did not influence the ability to maintain sugar beet quality in large outdoor piles. The length-removal method of pile management had better quality sugar beets compared with the standard end-removal method. Hence, sugar beet producers do not need to modify production practices to optimize storability, but sugar beet processors can improve sucrose recovery by removing sugar beets lengthwise along both sides of large piles as opposed to the standard end-removal method.

Postharvest jasmonic acid treatment of sugarbeet roots reduces rot due to Botrytis cinerea, Penicillium claviforme, and Phoma betae

Although jasmonic acid (JA) and JA derivatives are known to activate plant defense mechanisms and provide protection against postharvest fungal diseases for several horticultural crops, JA's ability to protect sugarbeet ( Beta vulgaris L.) roots against common causal organisms of storage rot is unknown. To determine the potential of JA to reduce rot due to three common sugarbeet storage pathogens, harvested roots were treated with JA concentrations of 0.01, 0.1, 1, 10, or 100 μM, inoculated with Botrytis cinerea, Penicillium claviforme, or Phoma betae, and evaluated for the severity of rot symptoms after incubation at 20 °C and 90% relative humidity. JA concentrations of 0.01–100 μM significantly reduced rot due to all three pathogens. All concentrations of JA provided statistically equivalent control against B. cinerea and P. betae, and reduced the amount of rotted tissue due to these pathogens by an average of 51 and 71%, respectively. Against P. claviforme, JA concentrations of 0.01–10 μM were equally effective and reduced rot by an average of 44%, while an increase in JA concentration to 100 μM reduced rot by 65%. Against all three pathogens, JA treatment did not affect the incidence of infection, but reduced rot by reducing the progression of disease symptoms in root storage tissue.

Considerations of the technological quality assessment of sugarbeet

No real improvement in the technological quality of beet has been recorded over the last 15 years in Northern Italy. Among the possible explanations for the quality stagnation is that the traditional formulae cannot correctly differentiate between sugarbeet varieties which produce thick juice of very high purity. This seems to be connected with the role of potassium. The use of a standard purification procedure gives reliable and accurate data which is immediately comparable with the factory data. Research projects on medium/long term storage are currently being performed by Co.Pro.B., Italy, in cooperation with Syngenta and Beta. Up to now the results have shown that storage of sugarbeet in autumn time in northern Italy is possible provided that suitable varieties and proper handling of the roots are employed. Results obtained in the storage trials are reported. Correlations have been found between quality parameters (purity, color and lime salts) of the purified juice with the glucose content of the raw juice. An interesting correlation is reported between purified juice purity and raw juice purity.

Sugar Beet as an Energy Crop

The combination of volatility in the oil market and finite oil resources and the effect on global climate change from the addition of CO2 to the atmosphere as a result of burning fossil fuels has increased the interest in sustainable energy generation from renewable biofuels. Most 1st generation biofuels in current production are liquid with bioethanol the product of fermentation. Sugar beet provides an abundance of sucrose, which is easily fermented by many microbes and on a per hectare basis; sugar beet is one of the most efficient sources of ethanol, however storage of harvested roots is problematic. Most studies have indicated sustainable biofuels have reduced greenhouse gas emissions (GHG) when compared to petroleum based fuels. Bioethanol from sugar beet reduces GHG comparably or superiorly to maize or sugarcane. There also are other biofuels from fermentation, including biomethanol, biobutanol ETBE, biomethane, and biohydrogen, many of which are more energy dense than ethanol. Storage of sugar beet is a problem that could be solved by ensilage and anaerobic digestion producing a biogas, which could yield more energy per hectare than bioethanol. As the global economy moves away from fossil fuels, sugar beet will play an increasing role in the adoption of more sustainable energy generation.

Ethylene production and ethylene effects on respiration rate of postharvest sugarbeet roots

Ethylene elevates respiration, is induced by wounding, and contributes to wound-induced respiration in most postharvest plant products. Ethylene production and its effects on respiration rate, however, have not been determined during storage of sugarbeet ( Beta vulgaris L.) root, even though any elevation in respiration due to ethylene would increase storage losses and reduce postharvest quality. To determine the effect of ethylene on sugarbeet root storage respiration rate, sugarbeet root ethylene production was quantified, and the effects of exogenous ethylene, an ethylene biosynthesis inhibitor, and ethylene response inhibitors on root respiration rate were determined using uninjured, severely injured, and conventionally harvested roots. Ethylene production was low (0.045–0.047 pmol kg −1 s −1) in uninjured and conventionally harvested and piled roots. Consequently, ethylene concentrations in commercial piles 0–67 d after piling were low, ranging from <0.001 to 0.054 μL L −1. Exogenous ethylene at concentrations of 0.020–14 μL L −1 increased root respiration. The increase in respiration rate, however, was transient at ethylene concentrations ≤0.11 μL L −1 suggesting that any ethylene effects on respiration rate in commercial piles would be short term. Severe injury induced ethylene production an average of 3.7-fold and increased respiration rate 3–4 d after injury. Wound-induced ethylene production, however, was not directly responsible for wound-induced respiration since elimination of wound-induced ethylene production by the ethylene synthesis inhibitor aminoethoxyvinylglycine had no effect on wound-induced respiration. The ethylene response inhibitors 1-methylcyclopropene (1-MCP) and silver thiosulfate reduced wound-induced respiration 3–4 d after injury when applied after wounding. A portion of the increase in respiration due to wounding, therefore, required ethylene perception. However, when applied prior to wounding, 1-MCP elevated wound-induced respiration 3–4 d after injury, suggesting that blockage of ethylene receptors prior to injury was ineffective at eliminating ethylene perception after wounding, possibly due to the synthesis of new receptors after the injury. Moreover, 1-MCP effects on root respiration rate occurred only when roots were severely injured; 1-MCP had no effect on respiration rate of uninjured or conventionally harvested roots. Postharvest sugarbeet roots, therefore, produce ethylene, increase ethylene production in response to wounding, and respond to exogenous ethylene with an increase in respiration rate, but ethylene production and ethylene effects on root respiration rate are likely to be small under commercial storage conditions and of limited economic significance.

Carbohydrate remobilization from storage root to leaves after a stress release in sugar beet (Beta vulgaris L.): experimental and modelling approaches

SUMMARYCarbohydrate remobilization from the sugar beet storage root to support leaf regrowth after release from water stress was demonstrated by experimental and modelling approaches. Experimental trials were carried out in northern France in 1994 and 1995 and in southern France in 2005, in conditions that involved a succession of soil moisture stresses and re-hydrations. Drought stress slowed leaf growth and the subsequent release of stress resulted in regrowth. A second trial showed that after total defoliation, sugar beet was able to produce new leaves. It was assumed that this leaf renewal, observed at drought stress release or after defoliation, relied on the possibility of remobilizing carbohydrates from storage roots to above-ground organs. This assumption was tested through a heuristic modelling approach, involving the STICS crop model and its existing sub-model on remobilization. The relevance of these formalizations for sugar beet was tested on the experimental data to validate the plant behaviour concerning remobilization. The model succeeded in reproducing leaf area index (LAI) dynamic trends and particularly leaf re-growth after drought stress release or defoliation, despite an over-estimation of the drought stress effect involving an inaccurate simulation of the changes in LAI. Nevertheless, the model's ability to forecast accurately above-ground and storage root dry weight, as well as trends in LAI dynamics, showed that the assumptions made about remobilization were able to explain sugar beet behaviour.

Changes in the processing quality of sugar beet (Beta vulgaris L.) during long‐term storage under controlled conditions

SummaryLong‐term storage of sugar beet is an option to extend the processing campaign of the sugar factories in Europe. In the present study, changes in the processing quality of sugar beet were quantified during 110 days of storage at 7 and 20 °C. During storage, the concentration of sucrose decreased whereas K, Na, amino N, betaine, invert sugar and raffinose accumulated in the beets, i.e. quality was impaired markedly. At 7 °C, the changes in sucrose concentration were relatively small but the formation of invert sugar and raffinose caused considerable losses in beet quality. Thus, long‐term storage at low temperature is appropriate to prolong the campaign but processing costs will increase. Quality assessment with two formulae showed that measurements of K, Na and amino N are insufficient to evaluate stored sugar beets for recoverable sugar. Due to its increase in storage, the concentration of invert sugar should also be taken into account.

Postharvest Storage Losses Associated with Rhizomania in Sugar Beet.

During storage of sugar beet, respiration and rots consume sucrose and produce invert sugar. Diseases that occur in the field can affect the magnitude of these losses. This research examines the storage of roots with rhizomania (caused by Beet necrotic yellow vein virus) and the effectiveness of rhizomania-resistant hybrids in reducing postharvest losses. Roots of susceptible hybrids from sites with rhizomania had respiration rates 30 days after harvest (DAH) that ranged from 0.68 to 2.79 mg of CO2 kg-1 h-1 higher than roots of the resistant hybrids. This difference ranged from 2.60 to 13.88 mg of CO2 kg-1 h-1 120 DAH. Roots of resistant hybrids from sites with rhizomania had 18 kg more sucrose per ton than roots from susceptible hybrids 30 DAH, with this difference increasing to 55 kg Mg-1 120 DAH. The invert sugar concentration of susceptible hybrids from sites with rhizomania ranged from 8.38 to 287 g per 100 g of sucrose higher than that for resistant hybrids 120 DAH. In contrast, differences between susceptible and resistant hybrids in respiration rate, sucrose loss, and invert sugar concentration in the absence of rhizomania were relatively small. Storage losses due to rhizomania can be minimized by planting resistant hybrids and processing roots from fields with rhizomania soon after harvest.

Proline content of sugar beet storage roots: Response to water deficit and nitrogen fertilization at field conditions

Drought stress is one of the major factors causing profit loss of the sugar beet crop. The accumulation of proline, an indicator of water stress, has been reported in response to osmotic and salt stress in sugar beet leaves, but there is little information about its levels in storage roots. Proline in storage roots is potentially useful as indicator of situations that lead to decreased yield and quality of the root, such as drought stress and excess nitrogen. This study has been focused towards proline quantification in storage roots from field trials concerning irrigation, sugar beet variety and nitrogen fertilization. Water deficit is the main factor leading to proline accumulation in sugar beet roots. Excess N supply also increases proline levels, partially by increasing leaf area index (LAI) and exacerbating drought stress. The two varieties studied (Claudia and Ramona) had different responses to water shortage and to nitrogen. Maximum proline levels were measured in Claudia roots subjected to a combination of water shortage and excess N. A positive and significant correlation was found between proline and glucose levels in sugar beet roots, pointing to a relationship between stress responses, carbohydrate catabolism, and proline and glucose accumulation. This proposal was supported by the effect of treatments with di-1- p-menthene (anti-transpirant) and with DMDP (2,5-dihydroxymethyl-3,4-dihydroxypyrrolidina, a glycosidase inhibitor), which lead to decreased level of proline in non-irrigated Claudia sugar beet roots.

Fate of Fall-Applied Nitrogen Fertilizer for Sugarbeet

Because of cost concerns and more efficacious use of time, labor, and equipment, the majority of N fertilizer for sugarbeet (Beta vulgaris L.) production in the Red River Valley is applied in the fall. Field 15N-balance studies were conducted to determine the fate of fall-applied, 15N-labeled fertilizers in sugarbeet-production systems. In the first experiment, 55% of the urea-N applied at a rate of 84 kg N ha−1 to a Northcote silty clay was in sugarbeet tops and storage roots, 43% remained in the soil to a depth of 180 cm, and only 2% was unaccounted for. In a follow-up experiment, in which appreciable leaching of NO3, Br, and to a lesser extent urea-N occurred in the spring as a result of melting snow and rain, recoveries of urea-N and KNO3-N (applied at a rate of 112 kg N ha−1) to a Glyndon sandy loam were 58 and 67%, respectively, by the deep-rooting sugarbeet plants. Residual fertilizer N remaining in the soil was 37% for urea-N and 31% for KNO3-N. Unaccounted-for-N was only 5% for urea-N and 2% for KNO3-N. Fall application of urea and anhydrous NH3, but not NH4NO3, and delaying application as close as possible to soil freeze-up are recommended for sugarbeet production in the Red River Valley. When appreciable precipitation occurs between fall application of N fertilizer and sugarbeet planting in the spring, application of starter N fertilizer is also recommended.

Impact of temperature, length of storage and postharvest disease on sucrose catabolism in sugarbeet

Abstract Sucrose catabolism during postharvest storage of sugarbeet (Beta vulgaris L.) root has been the subject of several studies; yet, no consensus exists about the contribution of the major sucrolytic activities to postharvest sucrose loss. Because differences in storage temperature, length of storage, and the presence of storage pathogens may have contributed to the discrepant results from earlier studies, the impact of these three factors on sugarbeet root postharvest sucrose catabolism was determined. Sucrolytic activities and soluble carbohydrate concentrations were measured in roots exhibiting no pathological symptoms during storage at 6, 12, and 21 °C and in roots exhibiting severe rotting symptoms due to infection by Penicillium spp. and Botrytis cinerea during storage at 6 °C. Sucrose synthase was the predominant sucrolytic activity throughout storage, regardless of storage temperature, length of storage, or pathogenesis, and accounted for more than 90% of the total soluble sucrolytic activity present in roots. In disease-free roots, no significant change in sucrose synthase activity, soluble acid invertase activity, or insoluble acid invertase activity occurred in roots stored at 6 or 12 °C, although an increase in sucrose synthase activity was observed in roots stored at 21 °C. Alkaline invertase activity was impacted by the length of storage and exhibited a transient decline in activity at all storage temperatures. Glucose and fructose concentrations generally increased as a function of time in storage at 6, 12, and 21 °C. In roots with severe rot, insoluble acid invertase activity declined, sucrose synthase and alkaline invertase activities were unchanged, and soluble acid invertase increased seven-fold. The increase in soluble acid invertase activity was primarily due to the presence of fungal acid invertase isoforms. These results indicate that sugarbeet sucrolytic activities change little during storage, regardless of storage temperature, length of storage, and pathogenesis, and suggest that sucrose synthase, as the predominant sucrolytic activity in stored roots, is central to postharvest sucrose catabolism in sugarbeet roots.

Characterization of a Mak subgroup Cdc2-like protein kinase from sugar beet (Beta vulgaris L.).

The Mak-type Cdc2-like protein kinases are, a relatively uncharacterized group of proteins. Bvcrk2 encodes a plant Mak-type kinase. Its highest levels of expression occur in the secondary meristems of developing sugar beet storage organs, suggesting a role, in planta, in the regulation of cell division or early cell differentiation.

Radial and axial water transport in the sugar beet storage root

To evaluate the contribution of transcellular, apoplastic and symplastic pathways to water movements, horizontal (axial pathway) and vertical (radial pathway) sugar beet root (Beta vulgaris L.) slices were studied. Volume flows (J v ) were measured under hydrostatic and/or osmotic gradients, using a computer-based data-acquisition system. When tissues were tested under hydrostatic gradients (0.3 MPa m -1 ) a much more important permeability was observed in the axial pathway, as compared with the radial one. Negative pressure gradients (tensions) were as effective as positive ones in inducing a net water movement. After the establishment of a concentration gradient in the radial pathway (obtained by adding 300 M m -3 mannitol to the employed solution) an osmotic flux, sensitive to HgCl 2 , was observed. The inhibitory effect of mercurial compounds was reversed by β-mercaptoethanol while [ 14 C] mannitol unidirectional fluxes were not affected by mercurial agents. In the axial pathway, the presence of a mannitol gradient did not develop a sustained osmotic flux. After an initial J v in the expected direction, the J v reversed and moved in the opposite way. It is concluded that, in the sugar beet root, water channels play a significant role in water transfers in the radial pathway. On the other side, water and solutes are transported by a hydrostatic gradient in the xylem vessels. In general, these results extend and adapt to a storage root the 'composite transport model' first proposed by Steudle et al.

Radial and axial water transport in the sugar beet storage root

Radial and axial water transport in the sugar beet storage root