1,658 research outputs found
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Ethylene and 1-methylcyclopropene differentially regulate gene expression during onion sprout suppression.
No full textOnion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions,
however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-
methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown
how ethylene and 1-MCP elicit the same response. In this study, onions were
treated with 10 μL L(-1) ethylene or 1 μL L(-1) 1-MCP individually or in
combination for 24 h at 20°C before or after curing (6 weeks) at 20°C or 28°C
and then stored at 1°C. Following curing, a subset of these same onions was
stored separately under continuous air or ethylene (10 μL L(-1)) at 1°C. Onions
treated with ethylene and 1-MCP in combination after curing for 24 h had reduced
sprout growth as compared with the control 25 weeks after harvest. Sprout growth
following storage beyond 25 weeks was only reduced through continuous ethylene
treatment. This observation was supported by a higher proportion of down-
regulated genes characterized as being involved in photosynthesis, measured
using a newly developed onion microarray. Physiological and biochemical data
suggested that ethylene was being perceived in the presence of 1-MCP, since
sprout growth was reduced in onions treated with 1-MCP and ethylene applied in
combination but not when applied individually. A cluster of probes representing
transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or
in the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down-
regulated a probe tentatively annotated as an ethylene receptor as well as
ethylene-insensitive 3, suggesting that both treatments down-regulate the
perception and signaling events of
The effect of cultural and environmental factors on potato seed tuber morphology and subsequent sprout and stem development
No full textSeed crops of the variety Estima were grown in each of 2 years using two planting dates, two harvest dates, two plant densities and two irrigation regimes to produce seed tubers which had experienced different cultural and environmental conditions. The effects of these treatments on tuber characteristics, sprout production and stem development in the ware crop were then determined in subsequent experiments using storage regimes of 3 and 10 °C. Time of planting the seed crop affected numbers of eyes, sprouts and above ground stems in the subsequent ware crop because environmental conditions around the time of tuber initiation appeared to alter tuber shape. Cooler, wetter conditions in the 7 days after tuber initiation were associated with tubers which were longer, heavier and had more eyes, sprouts and above ground stems. In contrast, the time of harvesting the seed crop did not affect tuber shape or numbers of above ground stems and there was no interaction with tuber size. The density of the seed crop had no effect on any character measured and irrigation well after tuber initiation did not affect tuber shape, numbers of sprouts or numbers of stems. Seed production treatments, which resulted in earlier dormancy break, were associated with tubers that produced more sprouts and above ground stems, in contrast to the conventional understanding of apical dominance. Storage at 3 °C gave fewer sprouts, a lower proportion of eyes with sprouts and fewer stems than storage at 10 °C. The major effects on stem production appear to result from environmental conditions at the time of tuber initiation of the seed crop and sprouting temperature
Onion gene expression in response to ethylene and 1-MCP
No full textOnion is regarded as a non-climacteric vegetable. In onions, however,
ethylene can suppress sprouting while the ethylene binding inhibitor, 1-MCP (1-
methylcyclopropene) can also suppress sprout growth yet, it is unknown how ethylene
and 1-MCP elicit the same response. In this study, onions were treated with 10 μL L-1
ethylene or 1 μL L-1 1-MCP individually or in combination for 24 h at 20°C before or
after curing (six weeks) at 20 or 28°C then stored at 1°C. Following curing, a subset
of these same onions was stored separately under continuous air or ethylene (10 μL L-
1) at 1°C
Onions treated with ethylene and 1-MCP in combination after curing for 24 h
had reduced sprout growth as compared with the control 25 weeks after harvest.
Sprout growth following storage beyond 25 weeks was only reduced through
continuous ethylene treatment. This observation was supported by a higher proportion
of down-regulated genes characterised as being involved in photosynthesis measured
using a newly developed onion microarray. Physiological and biochemical data
suggested that ethylene was being perceived in the presence of 1-MCP since sprout
growth was reduced in onions treated with 1-MCP and ethylene applied in
combination but not when applied individually. A cluster of probes representing
transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or in
the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down52
regulated a probe tentatively annotated as an ethylene receptor as well as EIN3,
suggesting that both treatments down-regulate the perception and signalling events of
ethylene
Understanding the mechanisms behind onion bulb dormancy in relation to the potential for improved onion storage
No full textOnion (Allium cepa L.) is the most economically important Allium crop. Onion
cultivars adapted for growth in temperate regions require long days for bulb initiation, so the summer crop is stored over-winter. Deterioration in store is largely due to resumption of growth. Extended storage of onions is currently dependent on the synthetic sprout
suppressant maleic hydrazide, whose future use is uncertain due to pressure to reduce
residues in foods.
Abscisic acid (ABA) has previously been linked with dormancy in a relative of
onion (A. wakegi). Bulb ABA concentration in three onion cultivars (viz. Renate, Ailsa
Craig and SS1) with contrasting storage lives declined exponentially during controlled atmosphere (CA – 3% CO2, 5% O2; 2°C) storage at the same rate in each cultivar.
Sprouting occurred at a minimal ABA concentration (ca. 50-120 ng g-1 DW). It was
proposed that extended periods of high concentrations of ABA may delay sprouting.
An ABA analogue (PBI-365) and exogenous ABA, were applied as preharvest foliar sprays (cvs. Renate, Carlos, Dinaro, Hysam, Red Baron and SS1), or as postharvest bulb soaks (cv. Hysam) with the aim of increasing endogenous ABA concentration and, thereby, extending the storage period. Endogenous bulb ABA concentration was not affected. Bulb ABA concentration again decreased during storage at a range of temperatures (4, 12 and 20°C) and sprouting occurred at minimal ABA concentration (ca. 75-150 ng g-1 DW). After the onset of sprouting, ABA concentration increased again, probably due to synthesis by the sprout. The concentration of certain carbohydrates has
been linked with storage potential. No straightforward relationship between ABA and
non-structural carbohydrate (NSC; fructose, glucose, sucrose and fructans) metabolism
could be determined. It was therefore postulated that ABA is more likely to play a role in mediating cell elongation rather than cell division, or that minimal ABA concentration could be a trigger for remobilisation of carbohydrates.
Controlled atmosphere (CA) is used to extend storage life of onions; however, shelf-life can be compromised. The effects of the transition between CA (3 % CO2, 5 %
O2; 2°C) and air storage on ABA concentration, quality characteristics, respiration rate(RR) and NSCs in three onion cultivars (viz. Renate, Carlos and SS1) were investigated. The RR of the short storing cultivar, SS1, was greatest by ca. 0.5-fold. The RR increased on removal from CA storage, with no accompanying decrease in carbohydrate
concentration, indicating that the increased RR may have been a transient stress response.
Storage of onions cv. SS1 for three weeks in air, followed by three weeks CA was as
effective in suppressing sprout growth as six weeks continuous CA storage. Bulb ABA
concentration decreased significantly between the time of harvest and after curing.
Therefore the current practice of curing onions for extended periods at high temperatures could be reducing bulb ABA concentration, and therefore storage life.
The literature concerning the role of ethylene in onion storage is limited and
conflicting. The effect of 1-methylcyclopropene (1-MCP; an ethylene perception inhibitor) on sprout growth in onions cv. SS1 stored at a range of temperatures (4, 12 and 20°C) was investigated, along with quality characteristics, NSCs and ABA. Sprout
growth was reduced in onions treated with 1-MCP and stored at 4 or 12°C, but not at
20°C. Approximately 2-fold greater concentrations of sucrose, glucose and fructose were maintained in 1-MCP-treated bulbs stored at 12°C as compared with untreated bulbs. It appeared that 1-MCP reduced carbohydrate metabolism.
Both ethylene and ABA are highly likely to impact significantly on onion storage
life. The results are discussed in relation to the potential to influence storage life by
changes in horticultural practices, including the recommendation to re-evaluate the curing and drying protocol, and to investigate the possibility of delaying the start of CA storage
The effects of ethylene on sweetpotato storage
No full textSweetpotato (Ipomoea batatas (L.) Lam.) is an important food security crop in many parts
of the developing world. Despite its economic value and growing contribution to nutrition
and health in tropical and sub-tropical countries, sweetpotato has a short postharvest life.
Inhibition of sprout growth to permit long-term storage and marketing of the roots is a
major challenge in the sweetpotato industry. To date, no technically and economically
satisfactory method is available to extend the tropical storage of sweetpotato. Previous
studies have demonstrated the efficacy of both exogenous ethylene and the ethylene
perception inhibitor 1-methylcyclopropene (1-MCP) in suppressing sprout growth in
other root crops such as potato and onion, which display differential endodormancy. It
has been proposed, through studies by others, that ethylene and 1-MCP may also enhance
sweetpotato storage. In the present study, the physiological and biochemical effects of
exogenously applied ethylene and 1-MCP were further investigated. Cont/d
Storage of potatoes : effects of ethylene and 1-MCP on potato tuber quality and biochemistry
No full textPotatoes are widely consumed in UK and many other countries. There is a continuous
demand for potatoes all year around both from consumers and retailers such that several
postharvest technologies are being used to meet this demand. Sprouting is the main
phenomenon affecting both the quality and marketability of potatoes during long term
storage. Several sprout suppressants are widely used (e.g. maleic hydrazide and
chloropropham, but there are concerns over their toxicity such that alternatives have
been sought. Continuous exposure of potato tubers to ethylene (usually 10 µL L-
1
)
during storage was approved by the Chemicals Regulation Directorate since 2003. Even
though potatoes have been regarded as non climacteric, this study aimed to examine the
effect of different ethylene regimes in combination with or without
1-methylcyclopropene on physiological, biochemical and mechanical characteristics of
a selection of important UK cultivars. In 2008-2009, ten potato cultivars were examined
for their response to four different ethylene regimes during storage. Storage time and
ethylene treatments had a cultivar specific effect on all the measured parameters
(sprouting, sugars, texture). Ethylene applied after first indication of sprouting was as
effective at sprout inhibition as when applied continuously for certain potato cultivars;
therefore this could be considered as a more environmentally and economical
alternative for sprouting inhibition. In addition, sugar accumulation was retarded when
tubers were subjected to ethylene at the first indication of sprouting compared to those
treated with continuous ethylene. In 2009-2010, four potato cultivars were studied and
the effect of 1-MCP either before or after ethylene treatment on sprouting, respiration
rate, endogenous ethylene production and texture was investigated. 1-MCP is believed
to interact with ethylene receptors and therefore prevent or retard ethylene dependent
responses. 1-MCP seemed to effectively block ethylene binding sites when applied
before storage of tubers in ethylene resulting in less tuber sugar accumulation. In 2010-
2011, the effect and timings of 1-MCP and ethylene treatments on sprouting, tuber
respiration, endogenous ethylene production and sugars on two potato cultivars was
studied. 1-MCP effectively suppressed the action of ethylene in terms of the increase in
the respiration rate or ethylene production and sugar accumulation. Selected potato
samples were also analysed quantitavely for an array of phytohormone using a newly
developed UPLC QToF MS method. This method had the advantage of quantifying
simultaneously a significant number of plant growth regulators that are present in potato
(ABA and its metabolites, cytokinins and gibberellins)
Sprout Garden Community Agriculture Internship
No full textThis summer, I worked with the Sprout Garden and Farm here at Connecticut College. Sprout is a community garden that began as a few simple beds near Earth House in 2004, and has since grown into a farm about the size of an acre. It is almost completely student run and provides food for not only the Connecticut College community, but also the greater New London area. Working with the food sovereignty organization, F.R.E.S.H. New London, we provide hundreds of pounds of fresh food to the community. Sprout Garden is not only an organization dedicated to teaching students about the process of tending to and harvesting plants, but also one that promotes food justice in a place severely lacking in fresh, nutritious, and affordable food. Additionally, Sprout takes great care in making the space welcoming for any visitors
Bulletin: Number 399: The Spindling-Sprout Disease of Potatoes
No full text16 pages, 1 article*The Spindling-Sprout Disease of Potatoes* (Stewart, F. C.; Sirrine, F. A.) 14 page
Effect of seed size on sprout growth of potato
No full textDissertation (MSc (Agric): Agronomy)--University of Pretoria, 2006.The effects of seed size on sprout growth of potato seed pieces were investigated in controlled temperature conditions. The objectives were to quantify the effects of seed size, plant growth regulators (gibberellin and paclobutrasol) and calcium availability on sprout length, sprout and root dry mass, as well as the fraction of seed reserves utilised for sprout development. The interactive effect between seed size and temperature was also investigated Sprout length did not differ among seed pieces ranging from 1 to 8g in mass. For larger seed pieces sprout length, dry mass and dry mass per unit length, and the root dry mass increased with increasing seed size, reaching a maximum at a seed mass of 24g after 40 days. The smaller the initial seed piece the larger was the fraction of assimilates utilised for sprout growth. Sprout length and dry mass as well as assimilate mobilisation for growth, were promoted by dipping seed pieces in gibberellin solutions, with the greatest effect obtained with 30 ppm GA, the highest concentration used in the experiment. Paclobutrasol showed inhibiting effects on all growth parameters except for sprout thickness. The root dry mass did not differ among treatments. Sprout growth was enhanced by calcium availability, with the greatest effect obtained with exogenous supply of calcium at 10 mmol/I as CaS04. A similar effect was noticed when complete nutrient solution was supplied. CaC03 was less effective than CaS04. Calcium availability to sprout tips affected sprout growth only when the roots were deprived of nutrients. Sprout length of the two seed pieces (3 and 5g in mass) was similarly affected by temperature over time, with the sprouts at the low temperature initially shorter, but reaching the same lengths as those at the high temperature after 30 and 40 days. Sprout dry mass and thickness of 3 and 5g seed pieces were similarly affected by temperature, with higher dry mass and greater thickening at 16°C than at 26°C. Exposure to low temperature (16°C) was associated with the transfer of a large fraction of seed reserves to the sprouts.Plant Production and Soil Scienceunrestricte
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Essential Oils as Sprout Suppressants in Potato Storage
No full textAs the fourth most important staple crop, potato (Solanum tuberosum) plays an important role in global food security. Year-round demand necessitates the preservation of potato quality for many months including the suppression of potato sprouting during storage to minimize economic losses and food waste. Stricter regulations on allowable sprout suppressant chemicals have increased interest and investigation into alternative products with sprout suppressant properties. The objectives of this thesis were to evaluate the potential of 54 essential oils (EOs) as sprout suppressants in potato tubers and minitubers stored at room temperature and identify the most promising whole EOs and EO blends for further testing. The studies were carried out using cv. Ranger Russet, Terra Rosa, or Austrian Crescent potato tubers or cv. Bannock minitubers and were presented as (i) whole EO studies and (ii) EO blend study. Responses included longest sprout length, number of germinated eyes, and percent tuber weight loss. The whole EO studies examined the effect of 51 EOs on sprouting in cv. Terra Rosa and Ranger Russet potato tubers and cv. Bannock minitubers across 90 days of room-temperature storage. Cymbopogon citratus EO was observed to completely inhibit sprouting in Ranger Russet tubers over the entire 90-day storage period. Artemisisa herba-alba EO significantly suppressed both sprout length and number in Ranger Russet and Terra Rosa tubers and Bannock minitubers over the 90-day storage period. Myrtus communis, Melaleuca quinquenervia, Cistus ladanifer, Ocimum basilicum, Ormenis mixta, and Salvia sclarea EOs reduced sprout length for varying storage durations in Ranger Russet tubers. Similarly, Cinnamomum zeylanicum (bark) and Laurus nobilis EOs reduced sprout number. The EOs of Mentha spicata, Carum carvi, Prunus armeniaca, Cymbopogon flexuosus, Thymus vulgaris, Thymus capitatus, Coriandrum sativum (leaves and seeds), and menthol crystals significantly reduced both sprout length and number in Ranger Russet tubers and Bannock minitubers. For Terra Rosa tubers, EOs of C. carvi, C. flexuosus, T. vulgaris, C. sativum (seeds), and menthol crystals significantly reduced both sprout length and number. None of the EOs were associated with differences in percentage of tuber weight lost. The EO blend study evaluated three additional whole EOs and blends of these three EOs as sprout suppressants in cv. Austrian Crescent tubers stored at room temperature for 90 days. Thymus zygis and Melaleuca ericifolia EOs significantly suppressed both sprout length and number when used alone over the entire storage period. Interactions between T. zygis and Artemisia dracunculus EOs affected sprout length whereas interactions between M. ericifolia and A. dracunculus EOs affected sprout number. However, the optimum blend to minimize both sprout length and number ranged between 90.91% - 94.95% T. zygis EO and 5.05 – 9.09% A. dracunculus EO depending on desired storage length
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