Physiological disorders

What is it and why is it a problem?

Bolting is the formation of a flowering stem (scape) with an inflorescence in the first year of vegetation instead of forming a full-fledged bulb. For the gardener, this means that instead of a large, juicy bulb, the plant spends its resources on flowering and seed production. Such bulbs become coarse, with a thick neck, store poorly, and are practically unsuitable for long-term use. This is one of the most common problems when growing onions from sets.

Why do onions bolt?

Bolting is not a disease but a natural physiological process triggered in plants that have reached a certain age and size under the influence of low positive temperatures. This process is called vernalization (Rabinowitch, 1985; Brewster, 2008). In nature, it is necessary for the biennial plant to flower and produce seeds in its second year. However, if the sets or pickling onions have undergone vernalization before planting, the plant "decides" that its first year is already over and begins to flower immediately after rooting.

Key conditions for triggering bolting:

1. Bulb size. The critical factor for bolting is not so much the age but the neck diameter (growth point). It is generally accepted that plants with a neck diameter exceeding 6–7 mm or bulbs larger than 15–20 mm are capable of perceiving vernalization (Brewster, 2008; Rubatzky & Yamaguchi, 1997). This is why large sets are much more prone to bolting than small ones.

2. Temperature and duration of exposure. Vernalization occurs most actively at temperatures between 5°C and 15°C for 1–2 months (Rubatzky & Yamaguchi, 1997). Storing sets at such temperatures or planting them in soil that is too cold (early spring) is a direct path to mass bolting.

3. Humidity. High humidity during storage at vernalizing temperatures enhances the effect.

Interestingly, for some varieties and hybrids, bolting can be triggered not only by storage but also by field conditions: if cold weather (below +10°C) persists for a long time after planting, the vernalization process can complete in the soil (Brewster & Salter, 1980).

How to prevent bolting?

Preventing bolting is a complex task that begins when the sets are placed in storage.

What to do if scapes have already appeared?

If scapes do appear, they must be removed as early as possible, at the very beginning of growth, by breaking or cutting them off at the base. This will redirect nutrients to bulb formation, although the yield will still be lower and storage quality poorer. Removing scapes at the "bubble" (swelling) stage is most effective.

Summary

Bolting is a reaction to vernalization of large bulbs during storage or planting in cold conditions. To avoid the problem, control the size of the planting material, adhere to temperature regimes during storage, plant onions in warm soil, and prefer resistant varieties.

What is it and why is it bad?

Thick neck is a condition where, by harvest time, the bulb does not form a tight, well-closed neck, and the false stem remains thick, juicy, and elastic. The leaves do not lodge, or do not lodge completely, and the bulb does not acquire the characteristic covering scales and size for the variety. Such bulbs store poorly: pathogens easily enter through the open neck, moisture evaporates, and the onion quickly rots or dries out. Additionally, thick-necked onions have reduced marketability and transport worse.

Why doesn't the neck dry out?

The formation of a dry, closed neck is the final stage of bulb maturation when all growth processes cease, and photosynthates from the leaves and neck move into the bulb. If this process is disrupted, the neck remains fleshy. The main reasons are:

1. Excess nitrogen fertilizers during the period of bulb formation and filling. Nitrogen stimulates vegetative growth — the plant continues to produce new leaves rather than accumulate reserves in the bulb. The neck does not thicken properly and remains juicy (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

2. Excessive moisture at the end of the growing season. If it rains or watering continues during the ripening period, the plant does not receive the signal to enter dormancy. Neck cells do not lose turgor, and the drying process does not start (Akhatov et al., 2013).

3. Harvesting too early or too late. With early harvesting (leaves still green, not lodged), the neck does not have time to dry. If harvesting is delayed, secondary root growth and even sprouting are possible, but more often, it is simply over-ripening with cracking, while the neck often remains thick because old leaves do not completely dry off, and new ones begin to grow (Brewster, 2008).

4. Unsuitable variety or region. Short-day varieties grown in long-day conditions may not form a normal bulb and neck. Conversely, long-day varieties in short-day conditions do not enter the dormant stage, and the neck remains "alive" (Rubatzky & Yamaguchi, 1997).

5. Planting density. With sparse planting, the plant has excess nutrients and light, continues to build vegetative mass, and does not finish its vegetation. Too dense planting, conversely, can cause premature lodging, but the neck remains thin — that is not our case. Thick neck is more often associated with sparse planting or uneven emergence (Brewster, 2008).

6. High temperatures combined with humidity — such stress can delay maturation but more often causes other disorders, such as tissue wateriness. However, if heat alternates with coolness and rain, the neck may "linger" (Conn, 2012).

How to prevent thick neck?

Prevention aims to help the plant complete its vegetation on time and enter a dormant state.

What to do if thick-necked onions have already been harvested?

Such onions are unsuitable for long-term storage. It is best to use them first, within 1–2 months, or process them (drying, freezing). If storage is absolutely necessary:

• Drying at 30–35°C with good ventilation for 2–3 weeks may help partially dry the neck but does not guarantee full storage ability (Conn, 2012).
• Store separately from healthy bulbs, at reduced humidity (60–65%) and a temperature of 0...+2°C, regularly sorting and removing rotting specimens.

Summary

Thick neck results from excess nitrogen, moisture, too early or too late harvesting, or an improperly chosen variety. To avoid the problem, control the nutrition and watering regime, choose zoned varieties, and harvest onions at the optimal time, followed by high-quality drying.

What is it and why is it a problem?

Lack of bulb formation is a situation where onions grown from seeds or sets form a powerful clump of green leaves, but the bulb does not set, or grows very small, loose, without the characteristic swelling. The plant seems to "get stuck" in the vegetative phase and does not switch to accumulating reserves in the base. Obviously, you will not get a bulb harvest in this case — only greens, and often coarse ones. For the gardener, this is one of the most frustrating problems: all the effort for a result of "green onions" instead of large heads.

Why doesn't the onion form a bulb?

Bulb formation is based on a reaction to day length — this is a key photoperiodic mechanism. The bulb begins to form only when the day length exceeds a critical threshold specific to the variety. This threshold varies among different varieties. If conditions do not match the variety's genetic program, the bulb does not set (Rubatzky & Yamaguchi, 1997; Brewster, 2008; Rabinowitch & Kamenetsky, 2020).

The main reasons for the lack of bulb formation:

1. Mismatch between the photoperiodic type of the variety and the latitude of cultivation. This is the most common cause.

• Short-day varieties (tropical and subtropical) require 11–13 hours of daylight for bulb formation. In more northern regions, where summer days last 16–18 hours, they flower or do not form a normal bulb at all, going into greens and bolting (Rubatzky & Yamaguchi, 1997).
• Long-day varieties (northern, European) require 14–16 hours of day length or more. In southern regions with short days (less than 13–14 hours), they do not receive the necessary signal and grow leaves without forming heads. Sometimes small, loose "underdeveloped bulbs" are formed (Rubatzky & Yamaguchi, 1997).
• Too early sowing or planting in a short day. If the onion germinates and starts growing actively when the day length has not yet reached the critical length, the plant may spend too many resources on foliage. By the time the day becomes long, there is not enough energy left to form a large bulb, or the process starts with a delay, resulting in a small bulb.
• Insufficient temperature. Even with a suitable photoperiod, low temperatures (below 15°C) can slow down or completely block the response to day length. This is especially noticeable in cool summers. Temperatures in the range of 18–25°C are important for bulb setting (Brewster, 2008; Rabinowitch & Kamenetsky, 2020). At temperatures above 30°C, the process also slows down, but in temperate climates, cold is more often the problem.
• Excess nitrogen and overwatering. As we already mentioned, nitrogen stimulates vegetative growth. If much nitrogen is applied against the background of a suitable day length, the plant may ignore the signal to form a bulb and continue to grow foliage. A thick neck is a consequence of the same imbalance (Brewster, 2008).
• Lack of light (shading). Onions are very light-demanding. In shaded areas, the process of photosynthesis is weaker, and even with a suitable day length, carbohydrate accumulation is insufficient for bulb setting. Shading also changes the ratio of red to far-red light, which can shift the threshold for photoperiodic response (Brewster, 2008; Rabinowitch & Kamenetsky, 2020).
• Plant immaturity. It is believed that to perceive the photoperiodic signal, the plant must reach a certain minimum size (4–5 true leaves, neck diameter ~6 mm). If seedlings are too dense or weak, they may "not hear" the signal to start bulb formation (Rubatzky & Yamaguchi, 1997).

How to ensure bulb formation?

Success is 90% dependent on the correct choice of variety and planting dates for your region. The rest is agricultural practices.

What to do if the bulb does not set?

In the current season, it is almost impossible to fix the situation. You can only try:

• Use such onions as greens — they are still edible, though coarser than special salad varieties.
• If bulbs have started to set but are very small, they can be harvested and used for summer consumption, not expecting winter storage.

For the future — only the right variety and timing!

Summary

The lack of bulb formation is almost always a mistake in choosing a variety based on photoperiod. Short-day varieties do not work in the north, long-day varieties in the south. Secondary causes are cold, excess nitrogen, shading, and dense planting. To grow a full-fledged onion, study the characteristics of the variety and compare them with the day length in your region.

What are they and why are they bad?

Double and multiple-centered bulbs are bulbs where, instead of one central growth point, two or more separate bulbs are formed, fused at the base, or one bulb with several primordia. In the first case, a cross-section shows several separate bulbs sitting on a common base. In the second case, there is one bulb but with several internal primordia, noticeable in a transverse section: instead of one ring, there are two or more centers.

For the gardener, this is a serious problem: such bulbs store poorly, often have irregular shapes, are difficult to peel and slice, sprout faster, and rot. Single-centered bulbs with a clear concentric structure are valued in the market and for processing. Multiple-centeredness is a serious defect that reduces marketability and yield (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

Why do bulbs become double or multiple-centered?

The disorder is based on the uncontrolled awakening and development of lateral buds on the base of the mother bulb. Normally, when a bulb forms, only one central growth point develops, and lateral buds are suppressed. If this suppression weakens, several buds simultaneously develop into separate bulbs or primordia.

Main triggering factors:

1. Genetic predisposition. Some varieties and hybrids are initially prone to multiple-centeredness. Modern F1 hybrids are generally bred for single-centeredness, but there are exceptions (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

2. Growing from sets. Bulbs from sets have a greater tendency to form multiple primordia. This is because the set initially has more leaf primordia, and under favorable conditions, they can reorganize into bulbs (Rubatzky & Yamaguchi, 1997).

3. High temperature during bulb formation. When the day is long enough, and the air and soil temperatures are elevated (above 25–28°C), it can trigger the division of the central meristem and the awakening of lateral buds. This phenomenon is more common in hot climates (Brewster, 2008; Rabinowitch & Kamenetsky, 2020).

4. Sharp fluctuations in humidity. Uneven watering combined with high temperatures can destabilize the plant's hormonal balance and contribute to multi-primordium development. This is especially critical from the start of bulb setting to its filling (Rubatzky & Yamaguchi, 1997).

5. Planting depth. Too shallow planting of sets accelerates the awakening of lateral buds, increasing the risk of multiple-centeredness. Deep planting, conversely, reduces this risk (Chipman & Thorpe, 1977, cited in Rabinowitch & Kamenetsky, 2020).

6. Excessive nitrogen nutrition. As in other cases, excess nitrogen during bulb setting enhances vegetative processes and can stimulate the development of additional growth points (Brewster, 2008).

7. Damage to the central bud (e.g., by frost, hail, insects). If the central growth point is damaged, lateral buds "get out of control" and begin to develop, leading to the formation of several bulbs in one nest (Conn, 2012).

How to prevent the appearance of double and multiple-centered bulbs?

Most measures aim to minimize stress and maintain stable conditions during bulb setting and filling.

What to do if multi-primordium bulbs are noticeable in the garden?

Unfortunately, this cannot be corrected in the current season. Such bulbs can be used:

• Primarily for summer consumption.
• For processing — pickling, drying, freezing.
• They are unsuitable for storage: their shelf life is drastically reduced; they often produce dormant buds that sprout in storage.

When selecting sets for planting, try to choose smaller, rounded ones without obvious signs of multiple growth points (sometimes they are visible to the naked eye — the set may be slightly flattened or have two apical buds).

Summary

Double and multiple-centered bulbs result from the failure to suppress lateral buds. The main causes are genetics, using sets, overheating, uneven watering, excess nitrogen, and damage to the central bud. Prevention involves choosing the right varieties, deep planting, stable watering, and proper nutrition. For long-term storage and processing, choose single-centered varieties and grow onions from seeds.

Next — Section 5. Splitting (Cracking) of Bulbs.

What is it and why is it bad?

Splitting of bulbs is the appearance of longitudinal or transverse cracks on the outer dry and fleshy scales, often penetrating deep into the bulb down to the base. Cracks can be superficial or deep, splitting the bulb into segments. For the gardener, this means not only a loss of marketable appearance but also a serious reduction in storage ability — pathogens easily enter through the cracks, the bulb loses moisture faster, and dries out. Cracked bulbs are unsuitable for long-term storage and are often rejected during sorting (Rubatzky & Yamaguchi, 1997; Conn, 2012).

Why do bulbs crack?

Cracking is a purely physiological disorder associated with sharp fluctuations in growing conditions, especially moisture and temperature. The bulb grows unevenly: internal tissues grow faster than external ones, or one part of the bulb grows faster than another, leading to internal tension and tissue rupture.

Main reasons:

1. Uneven moisture — the most common cause. A sharp transition from drought to abundant watering or rain causes a rapid growth of inner scales, while the outer, already dried and less elastic scales cannot stretch and crack. It is especially dangerous if, during the bulb-filling period, heavy rains follow a long drought (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

2. Sharp temperature changes. Alternation of very hot and cool weather disrupts normal tissue growth. With sharp warming, bulb growth accelerates, and with cooling, it slows down. These fluctuations create tension in the tissues and provoke cracking (Conn, 2012).

3. Uneven planting density. In sparse areas, where bulbs grow freely, they gain size faster but less evenly, increasing the risk of cracking. In dense areas, bulbs are smaller and crack less often, but this reduces the overall yield (Rubatzky & Yamaguchi, 1997).

4. Excess nitrogen and rapid growth. Nitrogen stimulates intensive tissue growth but makes them looser and less elastic. With sudden changes in conditions, such tissues rupture more easily (Brewster, 2008).

5. Genetic predisposition. Some varieties are more prone to cracking. For example, short-day varieties with large, flat bulbs crack more often than dense, round long-day varieties (Rubatzky & Yamaguchi, 1997).

6. Overripening of bulbs. If onions are left in the ground after full maturity and then the soil is suddenly moistened, the bulb may start secondary root and leaf growth, often accompanied by cracking (Brewster, 2008).

7. Root damage during cultivation or lifting. If the root system is damaged at the end of the growing season, water supply is disrupted. Then, with the resumption of watering or rain, an imbalance in tissue growth occurs — cracks are almost inevitable (Akhatov et al., 2013).

How to prevent bulb cracking?

Prevention is aimed at creating the most stable growth conditions and carefully completing the growing season.

What to do with cracked bulbs?

Such bulbs cannot be stored for long periods. They should be:

• Used for food first — within 1–2 weeks after harvest.
• Processed — frozen, dried, pickled.
• Definitely rejected during storage — even one cracked bulb can become a source of rot that spreads to neighboring ones.
• If cracks are superficial and dry, you can try using the onion for short-term storage in a cool, dry place, but sorting regularly.

Summary

Cracking results from uneven bulb growth due to fluctuations in moisture, temperature, or nutrition. The main prevention is stable watering without sharp transitions from drought to waterlogging, timely harvesting, choosing resistant varieties, and avoiding excess nitrogen. Cracked bulbs do not store well — use or process them first.

What is it and why is it bad?

Sunscald is damage to onion tissues by direct sunlight, accompanied by overheating and cell death. It appears as discolored, watery, then browning and drying areas on bulbs or on seedlings at the soil surface. For the gardener, this is a problem that occurs mainly in two stages: on young plants and, more often, on ripening bulbs during harvest and drying. Damaged tissues become entry points for bacterial and fungal infections, bulbs lose their marketable appearance, and their storage ability drops sharply. Also, sunscald is often confused with other diseases, leading to incorrect actions (Conn, 2012; Rubatzky & Yamaguchi, 1997; Akhatov et al., 2013).

Why does sunscald occur?

It is based on thermal damage when tissue temperature rises to a critical level (above 45–50°C). Onions are especially vulnerable when their covering scales are not yet dry or when they are abruptly pulled from moist soil and exposed to direct sunlight.

Main reasons:

1. Drying bulbs in the sun after harvest. This is the most common cause of sunscald for gardeners. If pulled onions are left on the bed in direct sunlight, especially in hot weather, the outer scales overheat, lose moisture unevenly, and the tissues die. Bulbs with wet, immature necks are particularly affected (Conn, 2012; Rubatzky & Yamaguchi, 1997).

2. Overheating of young seedlings at the soil surface. In hot weather, dark soil in the sun can heat up to 60–65°C at a depth of 1–2 cm. Young, tender seedlings in the root neck zone receive heatstroke, the tissue softens and dies, and the plant lodges and dies. This often happens when sowing onion seeds in hot periods, when seedlings emerge in the hottest part of the day (Conn, 2012; Rubatzky & Yamaguchi, 1997).

3. Insufficient hardening of bulbs before drying. If bulbs are dug from moist soil and immediately placed in the sun, active metabolism is still occurring in them, and overheating is deadly. They need time to adapt (Conn, 2012).

4. Damage to covering scales. If the outer scales are damaged, the inner, more succulent tissues are unprotected from the sun and overheat faster, worsening the situation (Akhatov et al., 2013).

5. Variety characteristics. Varieties with thin, delicate covering scales are more susceptible to sunscald than thick-skinned varieties with yellow or red husks (Rubatzky & Yamaguchi, 1997).

How to prevent sunscald?

Prevention involves proper organization of drying and protecting seedlings from overheating.

What to do if sunscald has already occurred?

Damaged bulbs:

• Immediately use for food or processing. They are not suitable for long-term storage.
• With light damage, you can try storing them separately from healthy ones, but in a cool, dry place, and use them first.
• If sunscald is accompanied by watery areas — such bulbs will start to rot, and they must be removed to prevent infection from spreading to healthy onions.

Never place sunburned onions in a common storage pile — they will become a source of bacterial and fungal rots (Conn, 2012; Akhatov et al., 2013).

Summary

Sunscald results from overheating of bulbs or seedlings under direct sunlight. The main prevention is proper drying (in the shade, protected by leaves, without sudden changes in moisture and temperature). Damaged onions do not store; use or process them immediately. For seedlings, use mulching or shading on hot days. Remember: onions like the sun for growth, but not for drying after harvest!

What is it and why is it bad?

Internal sprouting is the premature development of a green sprout inside the bulb, while externally the bulb may look perfectly healthy with dry, tight scales. The gardener often discovers the problem only when cutting the bulb: a bright green or yellow-green sprout is found inside, sometimes already with roots. Such bulbs have a bitter taste, their tissues become soft and loose, they quickly lose moisture, and become inedible. This is one of the most insidious storage problems because the onion looks normal externally, but an irreversible process is already underway inside (Rubatzky & Yamaguchi, 1997; Brewster, 2008; Conn, 2012).

Why do bulbs sprout internally?

The phenomenon is based on a violation of the natural dormancy state of the bulb. Normally, after maturation, the onion enters a period of physiological dormancy lasting from 4 to 8–9 weeks depending on the variety. During this time, the apical bud does not grow, even if conditions for growth are favorable. When dormancy ends, if temperature and humidity promote growth, sprouting begins. Internal sprouting is a situation where the bud awakens prematurely or proceeds secretly, without immediately breaking through the outer dry scales.

Main causes of premature or hidden sprouting:

1. Violation of the temperature regime during storage. This is the main cause. Storage in the 5–15°C range sharply shortens the dormancy period and stimulates bud awakening. Storage at 10–12°C is especially dangerous, as sprouting occurs at maximum speed. Storage at 0...+2°C or above +20°C, conversely, suppresses sprouting (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

2. High air humidity during storage. Relative humidity above 75–80% combined with "dangerous" temperatures accelerates bud awakening and encourages the sprout to grow before the outer scales are completely dry (Brewster, 2008; Conn, 2012).

3. Delayed harvesting. If bulbs remain in the ground after full maturity, the dormancy period may be shortened before harvest. Especially if rain has fallen after lodging and new roots have started to grow — such bulbs may already have an internal sprout formed by the time of harvest (Rubatzky & Yamaguchi, 1997).

4. Incomplete maturation. Bulbs that have not undergone a full ripening stage have a weakened dormancy period. Their apical buds "did not fall asleep completely" and are ready to start growing at the slightest change in conditions (Brewster, 2008).

5. Genetic predisposition. Short-day varieties with low dry matter content generally have a shorter dormancy period and tend to sprout early. Long-day, high-dry-matter varieties store better (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

6. Damage during harvest or storage. Any injury to the neck or base can disrupt the mechanisms restraining bud awakening and trigger premature sprouting (Conn, 2012).

7. Too warm and moist pre-harvest summer. In some regions, if the summer is very warm, onion maturation occurs faster, and the dormancy period may end earlier than expected. This is especially true for varieties sensitive to heat (Rabinowitch & Kamenetsky, 2020).

How to prevent internal sprouting?

Prevention begins at harvest and continues throughout the storage period.

What to do if onions start sprouting?

If internal sprouting has already begun, stopping it is practically impossible, but losses can be minimized:

• Use sprouted bulbs first. They have already lost some nutrients and become bitter but can be used in cooking.
• If the sprout is still small, you can try removing the central part and using the remaining fleshy scales.
• To temporarily slow growth, you can lower the temperature to 0...+1°C or raise it to +30...+35°C (but this is difficult in amateur conditions).
• Do not store sprouted bulbs together with healthy ones — they will accelerate the sprouting of neighbors.

Summary

Internal sprouting is the premature awakening of the apical bud, caused by improper temperature storage regimes, high humidity, delayed harvesting, or incomplete maturation. Prevention involves proper cooling or warming during storage, maintaining low humidity, choosing storage-resistant varieties, and timely harvesting with thorough drying. Sprouted onions do not store long — use them first.

What is it and why is it bad?

Tissue wateriness is a physiological disorder where the inner fleshy scales of the bulb lose their normal density and become watery, semi-transparent, and glassy in appearance. On a cut, such a scale resembles tissue that has "cooked" or become damp: it is grayish-yellowish, flabby, often with a watery tint. The outer dry scales may look perfectly normal, without signs of rot or damage. The problem is usually discovered 3–4 months into storage when the onions are already stored, and it may not be visible externally. Watery scales quickly soften, become a breeding ground for bacteria and fungi, and the bulb rots completely. This is one of the most insidious storage disorders as it is invisible in the early stages and leads to mass losses (Conn, 2012; Brewster, 2008; Rubatzky & Yamaguchi, 1997).

Why do tissues become watery?

Wateriness results from a metabolic disorder and damage to cell membranes in the fleshy scales. This occurs due to unfavorable conditions during harvest, drying, and the initial stage of storage. Unlike bacterial rot, there is no pathogen here — it is a purely physiological tissue breakdown, later complicated by secondary microflora.

Main reasons:

1. Overheating of bulbs during drying or storage. This is the most common cause. If, after harvest, onions are dried at too high a temperature (above 35–40°C) or left in the sun, the internal tissues overheat, membrane structure is disrupted, and scales become watery. This is especially dangerous if overheating occurs while the bulbs are still wet and have not undergone primary drying (Conn, 2012; Rubatzky & Yamaguchi, 1997).

2. High humidity and insufficient ventilation in storage. If in the first weeks of storage, humidity exceeds 80% and ventilation is poor, the concentration of CO₂ and moisture increases inside the pile or bag. This damages cell membranes, and tissues become watery (Brewster, 2008; Conn, 2012).

3. Sharp temperature fluctuations in storage. Temperature fluctuations, especially a transition from higher to lower temperatures at high humidity, can cause condensation on the surface and inside the bulbs, disrupting tissue integrity (Conn, 2012).

4. Damage during harvest. Even minor mechanical injuries can trigger tissue degradation. Damaged cells regulate water balance poorly and soften faster (Rubatzky & Yamaguchi, 1997).

5. Insufficient drying before storage. If bulbs are harvested wet, with an undried neck, and immediately placed in storage, respiration processes are intense, releasing heat and moisture, creating ideal conditions for wateriness (Conn, 2012).

6. Genetic predisposition. Some varieties, especially those with low dry matter content and thin scales, are more prone to this disorder (Brewster, 2008).

7. Long-term storage at temperatures above 0°C. When stored in warm conditions, metabolic processes accelerate, cells age, and wateriness can develop even at the correct humidity (Rubatzky & Yamaguchi, 1997).

How to prevent tissue wateriness?

Prevention is aimed at controlling temperature and humidity at all stages — from harvest to storage.

What to do if wateriness is detected?

Unfortunately, there is no reversing this process — damaged tissues do not recover. The task is to minimize losses:

• Immediately sort the onions. Remove all bulbs with watery scales. Even if wateriness has affected only one or two scales, the bulb will quickly rot.
• Affected onions should be used for processing or food in the coming days.
• Check the storage conditions of the remaining onions: if necessary, lower the temperature, increase ventilation, and reduce humidity.
• If wateriness is widespread, the onions were likely harvested immature or overheated — in this case, it is best to sell or process the entire crop.

Summary

Tissue wateriness is a physiological damage caused by overheating, sharp fluctuations in humidity and temperature, poor ventilation, and mechanical injuries. It manifests as glassy, watery scales that rot quickly. Prevention: proper drying, optimal storage conditions, careful harvesting. Detected damaged onions should be immediately removed and used first. Storage ability directly depends on how precisely you maintain the "temperature-humidity regime" at all stages.

What is storage ability and why is it important?

Storage ability is the capacity of onions to maintain their consumer qualities over a long period after harvest. For the gardener, this is essentially the main criterion for successful onion cultivation, as the primary goal is to provide the family with high-quality onions for the entire winter and spring until the new harvest. Loss of storage ability means that the onions begin to spoil, sprout, rot, dry out, or lose flavor within a few weeks or months of storage, rendering all efforts useless.

Storage ability is not an independent property; it is determined by a complex of factors we have discussed in previous sections: bolting, thick neck, multiple-centeredness, cracking, internal sprouting, tissue wateriness — all these disorders directly reduce the onion's ability to store. Additionally, other equally important conditions influence storage ability, which we will now summarize (Rubatzky & Yamaguchi, 1997; Brewster, 2008).

Why do onions lose storage ability? Main reasons

All causes of storage ability loss can be grouped into several categories:

It is important to understand: storage ability is built in the garden, not in the storage facility. If the onion is grown incorrectly, no storage conditions can save it. Conversely, properly grown and matured onions can last until the new harvest even in less than ideal conditions (Rubatzky & Yamaguchi, 1997).

How to improve storage ability? A comprehensive strategy

Improving storage ability is a complex of measures that starts with variety selection and ends with controlling conditions in storage. Here are the main steps.

What to do if storage ability is already reduced?

If you notice that onions are starting to spoil or sprout actively, act quickly:

1. Sort the entire stock, remove all suspicious bulbs.

2. Lower the temperature (if possible) to 0...+1°C to slow respiration and sprouting.

3. Increase ventilation and, if necessary, reduce humidity.

4. Plan the use of remaining onions: first consume those with the slightest signs of disorder.

5. As a last resort, if losses are high, process the onions.

Summary

Storage ability is an integral indicator of onion health. It depends on the variety, growing conditions, harvesting, drying, and storage. To store onions for a long time, choose storage-resistant varieties, provide proper nutrition and watering, harvest at the optimal time, dry correctly, and create stable conditions in storage. Regular monitoring and timely sorting will help minimize losses. Remember: storage ability is created in the garden, not in the cellar — attention to detail at all stages will give you a guaranteed supply of high-quality onions for the whole winter.