Methods to Minimize the Effect of Ethylene Sprout Inhibitor on Potato Fry Colour

Ethylene is an effective potato (Solanum tuberosum L.) sprout inhibitor, but it often darkens fry colour. Trials were conducted over nine consecutive storage seasons to identify ethylene application methods which would mitigate darkening while retaining adequate sprout inhibition, using cv. Russet Burbank plus cvs Shepody, Asterix and Santana in some years. Tubers were stored for up to 35 weeks in closed chambers with ethylene gas delivered via the ventilation airstream. Exposure to continuous 4 μl l⁻¹ ethylene after suberization and cooling were completed was designated the ethylene check. Alternative ethylene treatments included commencing exposure either before or after suberization was completed; gradually introducing the ethylene either by a concentration gradient of eight steps over 4 or 8 weeks or by increasing the duration of exposure from 6 to 24 h per day in four weekly steps; repeatedly interrupting exposure for several hours per day or for durations of 1 or more days; and warm storage. Selected ethylene treatment combinations were applied in each year, plus untreated controls, chlorpropham-treated (CIPC) checks and ethylene checks. Sprout growth, fry colour, loss of mass and disease incidence were evaluated at regular intervals. In all cultivars and all years, the ethylene check darkened fry colour more than the other treatments. Commencing before suberization ended, gradually introducing the ethylene by either concentration or time gradient and interrupting the exposure all reduced the negative effect of ethylene sprout inhibitor on fry colour. Continuous ethylene treatments inhibited sprout growth as effectively as CIPC, except at 13 °C storage. Interruptions of 18 h and 2 or more days reduced sprout inhibition. Regardless of cultivar variations, an early start using either a concentration or time-increment gradient had the least effect on fry colour while maintaining good sprout inhibition.     

Auxin-induced sprout growth inhibition: Role of endogenous ethylene

The role of endogenous ethylene in auxin-mediated tuber sprout growth inhibition was determined in potato (Solanum tuberosum L. cv. Russet Burbank) minitubers. Treatment of tubers with biologically active auxins resulted in a transient, dose-dependent increase in ethylene production and inhibition of sprout growth. Biologically inactive auxin analogs elicited neither response. Continuous exposure to > 0.001 μL L^-1 exogenous ethylene inhibited sprout growth in a dose-dependent manner with complete inhibition occurring at ethylene concentrations ≥1 μL L^-1. In further studies with the active auxin α-naphthalene acetic acid (NAA), the role of ethylene in auxin-induced sprout growth inhibition was determined using ethylene biosynthesis and action inhibitors. The ethylene biosynthesis inhibitor aminoethoxyvinylglycine reduced NAA-induced ethylene biosynthesis by over 80% but had no effect on sprout growth inhibition. The non-competitive ethylene action inhibitor silver thiosulfate had no effect on NAA-induced sprout growth inhibition. Similarly, both the competitive ethylene action inhibitor 2,5-norbornadiene and the irreversible action inhibitor 1-methylcyclopropene were ineffective in reducing NAA-mediated sprout growth inhibition. Collectively, these results do not support the proposal that, in the case of potato tuber sprouts, auxininduced growth inhibition is mediated by endogenous ethylene action.     

Sprout development and processing quality changes in potato tubers stored under ethylene: 1. Effects of ethylene concentration

Ethylene effectively inhibits sprouting of potatoes (Solanum tuberosum L.) during storage, but it often darkens fry color. The objective of the work described here was to determine if altering the concentration of ethylene applied would reduce the darkening while retaining adequate sprout inhibition. Trials were conducted over three consecutive years (1991–1992, 1992–1993, and 1993–1994). Tubers of cv Russet Burbank (ca 150–300 g) were stored at 9 C for 25 wk in closed chambers in a refrigerated room under continuous exposure to 0.4, 4, 40, or 400 µL L^?1 ethylene gas delivered with the ventilation airstream (ca 0.5 air exchanges per h, for 6 h each day). Untreated control and chlorpropham-treated (CIPC) check tubers were stored under the same conditions but without ethylene supplementation. Sprout number, length, and biomass, fry color, loss of tuber mass, disease, and dry matter content were evaluated at 5-wk intervals. Dose-dependent effects (400>40>4>0.4 µL L^?1) of ethylene on sprout growth and fry color were observed. The 400, 40, and 4 µL L^?1 ethylene treatments inhibited sprout growth as effectively as CIPC, whereas in 0.4 µL L^?1 ethylene sprouting was midway between CIPC and the untreated control. Sprout mass and maximum sprout length in all ethylene treatments were significantly lower (P<0.05) than in the untreated control. Compared with the initial value (57.3 Agtron reflectance units [ARu]), after 5 wk of storage fry color was up to 5 ARu darker in the ethylene treatments, but recovered steadily at the subsequent evaluation dates. At 25 wk of storage the fry color of tubers from the 40 and 4 µL L^?1 ethylene treatments were, however, still darker than tubers stored with CIPC. Inhibition of sprout growth was slightly more effective in the 400 and 40 µL L^?1 ethylene treatments than in 4 µL L^?1, although there were no significant differences (P<0.01) in fry color between these treatments. In comparison with the other ethylene treatments, fry color in 0.4 µL L^?1 ethylene was lighter, but inhibition of sprout growth was significantly (P<0.05) poorer. There were no differences in tuber disease incidence or dry matter content between the treatments. At 25 wk, the untreated tubers had ca 50% greater loss of tuber mass than any other treatment, attributable to their heavy sprouting. Loss of tuber mass in the ethylene treatments was not significantly different (P<0.001) from that in the CIPC treatment.     

Using Ethylene Gas and Chlorpropham Potato Sprout Inhibitors Together

Marketplace preference for lower pesticide residues in foods has led to research to reduce the residue of chlorpropham (isopropyl N-3-chlorophenyl carbamate; CIPC), a postharvest-applied sprout inhibitor which is widely used around the globe to prevent sprouting of stored potatoes (Solanum tuberosum L.). Ethylene gas, an effective, safe and non-toxic sprout inhibitor used in several countries, sometimes has negative effects on the colour of processed potato products when used alone. Trials were conducted over 3 years using cv. Shepody (French fry) and cv. NorValley (potato chips/crisps) to determine whether a combination of these two sprout inhibitors, at reduced dosages, could inhibit sprouting while maintaining good processing colour. CIPC applied at 0, 0.1, 0.25 and 1.0 times the recommended dosage was combined with 4 μll⁻¹ of ethylene gas applied or no ethylene at all (0 ethylene), for 1 day in 4 days, for 1 day in 2 days or continuously, in a factorial design. Sprout inhibition in both cultivars was excellent at all levels of CIPC application except the 0 rate. In both cultivars, sprouting was inhibited by the continuous ethylene treatment. However, all levels of ethylene exposure except the 0 rate negatively affected processing colour in both cultivars. The darkening was dose dependent, whereby the colour was darkest in continuous ethylene and was less affected by the intermittent exposures. In continuous ethylene, the colour was progressively lighter during storage after initial darkening. Shepody tubers appeared to be more sensitive to ethylene than the NorValley tubers. In Shepody only, colour in the ethylene of 1 day in 4 days treatments was progressively darker with increasing time in storage.     

Effects of ethylene and 1-methylcyclopropene on potato tuber sprout control and fry color

The study examined the efficacy of 1-methylcyclopropene (1-MCP), an anti-ethylene compound, as a preventative treatment for ethylene-induced fry color darkening in potato (Solanum tuberosum L.) tubers, without reducing the effectiveness of ethylene as a tuber sprouting control agent. The experiment was conducted for two years with ‘Shepody’ and ‘Russet Burbank.’ Tubers of each cultivar from four separate growers received one of the following treatments: Air (control), Air + 1-MCP (1 (μL.L^-1 for 48 h), isopropyl N (3-chlorophenyl) carbamate (chloropropham; CIPC; 1% a.i. [v/v]); continuous ethylene (4 μL.L^-1) in air; continuous ethylene pre-treated with 1-MCP once; continuous ethylene pre-treated with 1-MCP and repeated monthly; and continuous ethylene pre-treated with 1-MCP and repeated bi-monthly. Treatment started after suberization and cooling to 9 C, and samples were evaluated at 3-wk (year 1) or 4-wk (years 2 and 3) intervals thereafter until April (Shepody) or June (Russet Burbank). Sprout growth (sprout fresh weight per tuber), fry color (Agtron reflectance units), tuber weight loss, incidence of disease infection and internal disorders were evaluated. Weight loss, tuber infection, and the occurrence of disorders were not affected by any of the treatments. Sprout growth was controlled by the continuous ethylene supply in both cultivars, and single or multiple additions of 1-MCP to the ethylene treatment did not affect the ethylene control of sprouting. As expected, ethylene treatment alone enhanced fry color darkening in both cultivars. In Russet Burbank tubers, fry color was not darkened in any of the ethylene + 1-MCP (once, monthly, or bimonthly) treatments. In Shepody, fry color was not darkened in the ethylene + 1-MCP monthly or bimonthly treatments, but started darkening 4 wk after exposure in the single ethylene + 1-MCP treatment. It is concluded that 1-MCP can be used to control fry color darkening induced by ethylene without blocking ethylene control of tuber sprouting. However, the number of 1-MCP applications required may vary with the cultivar, e.g., one application was sufficient in Russet Burbank but not in Shepody.     

Assessment of Dormancy and Sprouting Behavior of CIP Elite and Advanced Clones Under Different Storage Conditions in Uzbekistan

In potato breeding and selection, storability should be regarded as equally important as yield, disease resistance, and quality. A study documenting the dormancy period, sprouting behavior, and weight loss of 17 International Potato Center potato elite and advanced clones was carried out in Tashkent, Uzbekistan, under cellar and cold store conditions, during 2008 and 2009. Ninety tubers of each of 17 clones were allocated to experimental units of 30 tubers each placed in trays and randomized in three replications following a random complete block design. Therefore, there were three replications of 30 seed tubers each per entry. The dormancy period ranged from 77 to 115 days and from 100 to 186 days under cellar and cold storage, respectively. There was a relatively high positive correlation (0.69) for dormancy period between storage systems, indicating that clones demonstrating longer and shorter dormancy periods under one system will also behave similarly under the other system. A negative correlation (−0.53 and −0.88) was found between dormancy period and length of the longest sprout in cellar and cold store, respectively, meaning that clones with shorter dormancy often showed a greater length of their longest sprout. The weight loss percentage per tuber was similar in both storage systems, from 5.0% to 8.0% in the cellar and from 5.0% to 9.8% in the cold store, although for different storage periods (an average of 110 and 166 days under cellar and cold storage conditions, respectively). The study indicated that under cellar conditions, clones with a longer dormancy period and slower rate of sprout growth have less weight loss during storage and therefore better keeping quality.     

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.     

The Combined Effect of CO2 and Ethylene Sprout Inhibitor on the Fry Colour of Stored Potatoes (Solanum tuberosum L.)

Recently, it has been shown that the darkening of potato processing colour attributable to a trace concentration of ethylene gas is more severe when CO₂ is also elevated. In view of the increasing use of ethylene gas for sprout suppression in potato storage facilities, it was considered important to determine whether this effect also occurs at the much higher ethylene concentration used in commercial practice. Sprouting and processing colour of the French fry cultivars Russet Burbank, Shepody and Innovator and the potato crisp cultivar Dakota Pearl were tested during the November to June storage season of two consecutive years. Treatments were 0 or 2 kPa CO₂ and 0 or 10 μL?L^?1 ethylene in a factorial design, plus a chlorpropham check. The 0 CO₂?+?0 ethylene treatment constituted an untreated control. The ethylene exposure was commenced abruptly to maximize its effect on colour. The main effect of ethylene resulted in darker processing colour in all cultivars, whereas darkening attributable to the main effect of CO₂ was observed only in Innovator and Dakota Pearl. The statistical interaction of the CO₂ and ethylene was not significant except in Dakota Pearl Hunter a (redness) scores, although a tendency to darker colour when both gases were present was seen in Russet Burbank and Innovator at all evaluation dates. The results indicate that both gases can affect processing colour when ethylene is used to control sprouting, although considerable variability in the response exists among cultivars. This variability in combination with management of storage conditions such as temperature and CO₂ can be utilized to minimize the impact of these gases on the processing colour of stored potatoes.     

盐胁迫对假臭草种子萌芽特性的影响

假臭草在无盐、低盐(0.75、1.5 g/L)及中度盐(3.0 g/L)胁迫下都可以正常萌发,说明假臭草种子耐盐能力很强,且低盐浓度有利于假臭草生长;高盐(4.5、6.0 g/L)浓度对假臭草种子的萌发有严重的抑制作用。实验表明,高浓度盐分不会对其造成致命伤,但种子萌发和生长变得缓慢;过高的盐浓度导致种子坏死,幼芽死亡,幼根腐烂。研究结果表明,假臭草对盐胁迫具有一定的耐受力和抵抗能力,能够适应一定的盐度环境。假臭草对盐胁迫具有一定的耐受和抵抗能力,能够适应一定的盐度环境,通过实验得知其幼苗生长的适宜盐度为     

A bioassay with excised potato shoot-tips for assessing the effect of growth-inhibiting volatile compounds in the potato

Summary A bioassay technique is described for assessing growth-regulatory activities of volatile compounds in the potato. Excised potato shoot-tips (3 mm) were cultured aseptically in an aqueous medium in the dark at 25°C. After 7–12 days in culture, growth rates were measured by the increase in length of the treated shoot-tips. The addition of low concentrations (1 μmol/l) of gibberellic acid (GA₃) and kinetin to the culture medium enhanced shoot growth. Known sprout suppressants inhibited growth of shoots in the bioassay. Of those tested 1,4-dimethylnaphthalene was found to be the most potent. The effectiveness of these known suppressants of sprout growth of whole potato tubers in inhibiting growth in the bioassay is presented as evidence of the validity of using this bioassay to detect unknown growth inhibitory volatile compounds evolved by stored potatoes.     

Seed characteristics and nutrient composition of selected beans (Phaseolus vulgaris L.) with different ozone tolerance

Ozone sensitivity, nutritional quality, seed characteristics, and growth habit of beans (Phaseolus vulgaris L.) were evaluated in two seperate experiments. In the first experiment the data showed a significant variation among 34 bean accessions for ozone sensitivity following acute exposure of 18-day-old plants to 0.6 µl/l O₃ for 2 hours under environmentally controlled greenhouse conditions. PI-163579, PI-169735, PI-171790, PI-176684, PI-201374, PI-310711, PI-345576, PI-370569, PI-379435, and PI-414831 were identified as tolerant to acute ozone exposures. Protein, oil, starch, sugar, and ash contents in the seed of selected germplasm were determined and no correlation was found between these components and ozone sensitivity. Seed size and growth habit varied considerably among the 34 accessions but were not correlated to ozone sensitivity. In a second experiment, ten accessions, selected from the tolerant ones identified in the first experiment, were subjected to chronic ozone exposure in open-top chambers at 0.04 and 0.08 µl/l concentrations for 7 hours/day 44 days after transplanting. Based on foliar injury and yield reductions, only PI-370569 and PI-414831 were tolerant to prolonged ozone exposure (0.08 µl/l). A significant positive correlation (r=0.83) existed between foliar injury rating from chronic treatments involving 0.04 and 0.08 µl O₃/l and acute exposure (0.6 µl O₃/1/2 hours). The data indicated that acute ozone exposure can be used to initially screen a large number of bean accessions, however, this is an imperfect indicator of ozone sensitivity with chronic exposure.Agricultural Research Station Journal Article Series, No. 191. The use of any trade name varieties and/or vendors does not imply the exclusion of other products or vendors that may also suitable.     

Dormancy and sprout development of some South African potato cultivars during cold storage

Summary Observations were made on dormancy and sprout growth of nine potato cultivars stored at 3–4°C, 7–8°C and 11–12°C, respectively. Tubers of the cultivar Vanderplank had a very long dormant period (232 days at 3–4°C) and showed little sprout growth at 180 days. The cultivar Koos Smit had a very short dormant period (92 days at 3–4°C) and developed considerable sprout growth at the higher temperatures. The reaction of tubers of Up-to-date and BP₁ were approximately the same, and intermediate between those of Vanderplank and Koos Smit.     

Dimethylnaphthalene and diisopropylnaphthalene for potato sprout control in storage: 1. Application methodology and efficacy

Dimethylnaphthalene (DMN) and diisopropylnaphthalene (DIPN) isomers applied as sprout suppressants to stored potatoes (cv. Russet Burbank) were evaluated for effects on sprout length and weight compared to chlorpropham (CIPC). One application of CIPC at 22 mg a.i. kg^-1 of tuber fresh weight (f.w.), and one or two applications of DMN and DIPN at 100, 200, and 300 mg a.i. kg^-1 f.w. were applied as thermal aerosol fogs. Two applications of DIPN at 300 mg a.i. kg^-1 f.w. were as effective as CIPC in suppressing sprout growth during ten months of storage. DMN also suppressed tuber sprout growth but was not as effective as two applications of DIPN or one application of CIPC. One application of DIPN or DMN at 300 mg a.i. kg^-1 f.w. was an effective suppressant of sprout growth on a short-term basis. Whole tuber residue analyses were also conducted. After ten months in storage, DMN and DIPN residue concentrations were equal to or less than those of CIPC.     

Slug damage and control of field slug (Deroceras reticulatum (Müller)) by carvone in stored potatoes

Summary After a wet autumn and harvesting under wet conditions, slugs brought into potato stores via clods and soil adhering to tubers may cause substantial damage by feeding on the tubers. A carvone sprout inhibitor, Talent^?, applied in the potato stores at a dose of 50 ml per tonne potatoes, controlled slugs within a few days. A dose of 25 ml carvone was insufficient. Using a laboratory box test, the slug (Deroceras reticulatum) affected only wounded tubers and, although slime was present on the unwounded potatoes, they were not damaged by slugs.     

A potato bud bioassay for use in assessing activities of endogenous growth substances in the potato

Summary A method is described for assessing the activities of growth substances using excised potato buds. Plugs containing an apical bud were excised and the cut surfaces wrapped in vitafilm. The buds were held for up to thirty days at 20°C without rotting. Daily treatment of buds for 5 days after excision, with either gibberellic acid or an extract of potato sprout promoted breaking of dormancy and growth of sprouts.     

Inhibition of potato sprout growth by carvone enantiomers and their bioconversion in sprouts

Summary The monoterpenes (R)-(−)-carvone and (S)-(+)-carvone inhibited sprout growth in a model system consisting of sprouts growing from potato eye pieces. The sprout tissue was not necrotic after carvone treatment and the inhibition was reversible, since after treatment the sprouts showed regrowth either by continued top growth or by branching. However, the effect of both isomers on sprout growth differed, and (S)-(+)-carvone inhibited the elongation of the sprouts sooner than did (R)-(−)-carvone. This might be explained by a faster uptake of the former, since the concentration of (S)-(+)-carvone and its derivatives was twice as high during the first 4 days compared with (R)-(−)-carvone-treated sprouts. The sprouts were able to reduce (R)-(−)-carvone mainly into neodihydrocarveol, and (S)-(+)-carvone into neoisodihydrocarveol; in addition hydroxylated compounds were also detected. To whom correspondence should be addressed     

稻茬过晚播扬麦25产量形成与氮素积累利用特征

为明确过晚播种(较适播期晚30 d左右)对小麦产量及氮素积累与利用的影响,2018-2020年以长江中下游地区主栽品种扬麦25为供试材料,在11月1日(适期播)和12月1日(过晚播)条件下设置225×104株·hm-2和375×104株·hm-2两种种植密度,分析过晚播和适期播小麦产量、氮素积累与分配和氮素利用效率的差...     

Physiological regulation of potato tuber dormancy

At harvest, potato (Solanum tuberosum L.) tubers are dormant and will not sprout. As the period of postharvest storage is extended, tuber dormancy is broken and sprout growth commences. The loss of tuber dormancy and onset of sprout growth is accompanied by numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous hormones have been proposed to play a significant role in tuber dormancy regulation. The involvement of all major classes of endogenous hormones in tuber dormancy is reviewed. Based on available evidence, it is concluded that both ABA and ethylene are required for dormancy induction, but only ABA is needed to maintain bud dormancy. An increase in cytokinin sensitivity and content appear to be the principal factors leading to the loss of dormancy. Changes in endogenous IAA and GA content appear to be more closely related to the regulation of subsequent sprout growth.     

The effect of controlled atmosphere storage at 4°C on crisp colour and on sprout growth,rotting and weight loss of potato tubers

Summary After three weeks curing at 10°C, potato tubers cv. Record were stored at 4°C under different controlled atmospheres (CA) for six months to study the effect on crisp fry colour, sprout growth and rotting. Combinations of low levels of CO₂ (0.7–1.8%) and low levels of O₂ (2.1–3.9%) gave a significantly lighter crisp colour, low sprout growth and fewer rotted tubers compared with 0.9% CO₂ and 21.0% O₂. Tubers stored in these conditions. showed a significantly higher weight loss and shrinkage after reconditioning. High CO₂: low O₂ combinations during storage completely inhibited sprout growth and caused the darkest crisp colour, but after reconditioning tubers gave the same level of sprouting and crisps as light as the other CA combinations. Furthermore these combinations, especially CO₂ at 10 or 15%, increased the onset of rotting. Also our results showed that at low concentrations of CO₂ (0.7–1.6%), and low O₂ (2–2.4%) there was an increase in tuber rotting.     

Growth Responses of Drought Resistant Rice Cultivars to Soil Compaction under Irrigated and Succeeding Non-irrigated Conditions during the Vegetative Stage

Abstract

We investigated whether drought resistant rice cultivars exhibit higher dry-matter production under wet and dry compacted soil conditions in the vegetative stage and determined the dominant factors governing resistance to soil compaction. Three rice cultivars, a drought-sensitive Nipponbare, and drought-resistant Senshou and Dular, were grown in pots at four soil bulk densities (SBD) ranging from 1300 to 1600 dry soil kg m^?3. Root and shoot dry matter productions was slightly smaller in Nipponbare over the 29 days after sowing under irrigated conditions than in the other cultivars at all SBDs. Senshou and Dular also maintained a higher dry matter production, both in relative and absolute values, than Nipponbare under the condition of withheld irrigation from days 29 — 39 after sowing. The higher stomatal conductance and leaf water potential of these two cultivars were supported by a larger root system which was mostly accompanied by lower top-root ratios in the irrigated and compacted soils. The higher plant growth rate under the non-irrigated condition might have been a result of both the higher water absorption rate and water use efficiency, which in turn were supported by the larger root biomass. We conclude that the ability of rice to rapidly develop a root system in the early vegetative phase under compacted soils facilitates plant production under subsequent soil desiccated conditions.