Effect of Moisture Content on seed preservation - Best Cold Storage In India | Cold Storage For Vegetables (2024)
Seed Storage is an essential step towards conserving plant genetic resources for the long term. Proper seed storage and maintenance retains its genetic integrity. Since very early days, several techniques were implemented to preserve seed viability in wild and domesticated resources. However, factors such as temperature, seed nature, relative humidity, moisture content, and so forth, led to a decline in seed longevity during storage. Seed moisture content is one of the mains reasons that affect the above case.
What should be the optimal seed moisture? Moisture content in seeds greatly depends on factors like length and type of storage structure and packaging material. Up to 10% moisture is satisfactory for cereals stored in ordinary storage conditions for 12-18 months. For seed storage in sealed containers, they should be dried up to 5-8% depending upon the species.
What leads to excessive seed moisture? When seeds do not get dried before storage, the high moisture content remains in them, leading to fungal growth and reduction in viability. However, sources say that seed moisture content below 4% may also lead to extreme desiccation or hard seediness in some crops.
Depending on the storage conditions and species, seeds can enhance their lifetime from a few years to centuries. Generally, seed storage takes place in cool and dry conditions. However, they tend to survive longer when stored in a wet and warm environment. The life of a seed mostly revolves around its moisture content. Therefore, it is necessary to dry seeds to safe moisture content.
How moisture content in seeds affect their preservation? Low moisture plays a major role in affecting seed preservation than low temperatures. Seed germination capacity mainly depends on the duration, preservation methods, long term storage, and drying. Factors like a slight increase in moisture content and temperature may promote fungal growth and insect development in seeds. This further leads to the decline of seed germination capacity and the eventual death of seeds.
How can we retain seed viability? For every 1% increase in seed moisture or ~5°C (10°F) temperature, the viability period decreases by half. To prevent that, they should be dried well and stored in controlled environments. Proper storage conditions effectively retain substantial viability in seeds over a considerable storage period. Dark places are the best for optimal seed storage. Although sunlight supports and stimulates the seed germination process, darkness helps keep the pre-germination processes in the seed at a low level.
Generally if the seed moisture content increases storage life decreases. If seeds are kept at high moisture content the losses could be very rapid due to mould growth very low moisture content below 4% may also damage seeds due to extreme desiccation or cause hard seededness in some crops.
The storage in sealed containers during upto 4-8% moisture content depending upon the particular kind of seed may be necessary. Desiccant like silicagel can maintain the moisture content in equilibrium with the Relative Humidity of 45%.
The principal factors determining the storage life of seeds are storage temperature and seed moisture content. For each rise of one percent in moisture content and for each rise of 5°C in temperature, the storage life of seed is halved (Harrington, 1973). Temperature is an important factor in affecting seed viability.
The seed moisture content is the most vital parameter which influence the seed quality and storage life of the seed. Viability decrease more rapidly at high moisture content because of mould growth, heating damage, ageing and increased insect image.
The ideal storage temperature for seeds is 35-40°F with a relative humidity of less than 40%. Most refrigerators hold a temperature of about 40°F but have high relative humidity. Seeds stored in a refrigerator should be kept in containers that have a good seal to keep the humidity levels low.
The moisture content of the samples decreases with temperature, so that the most and least moisture content on dry basis, i.e. 2.721 and 1.148, belong to the sample dried at 60°C and 90°C, respectively.
The results also show that increasing time and temperature leads to a decrease in the moisture content of the samples, but it increases the value of rehydration and the shrinkage of samples.
A PRODUCT stored at too high a moisture content will deteriorate. It is therefore desirable to determine the moisture content of a product at different times, e.g. at harvest, during storage, and also on buying or selling where the risk of adulteration with water may be present if price differentials are in operation.
The health of our crops relies upon an adequate supply of moisture and soil nutrients, among other things. As moisture availability declines, the normal function and growth of plants are disrupted, and crop yields are reduced. And, as our climate changes, moisture availability is becoming more variable.
If there is a lack of oxygen supply from excess moisture, the plant growth is aggravated because the root cannot absorb nutrients and moisture (Hsiao and Jackson 1999). And this lack of moisture, a water stress, could cause abscission of leaves and reduction in leaf area and seed production (An et al. 2008).
Achieving good conditions for a safe storage requires limiting the grain temperature and maximum moisture content at grain reception. The recommended moisture content for grain storage depends on the grain type but shouldn't be higher than 14%.
... Drying can be used for reducing the moisture content of 80-95% in fresh fruits and vegetables (Santos et al. 2022;Prosapio and Norton, 2018;Waghmare, 2021). In order to safe storage, final moisture content of the fruits and vegetables should be reduced to less than 20% and 10 % respectively (Afolabi, 2014) .
In another definition, It has been defined as amount of water that can be removed without changing the chemical structure of grain. The amount of water in dry foodgrains varies from about 0.05kg/kg to 0.30kg/kg.
The two most significant factors that affect seed quality in storage are temperature and relative humidity. Seeds need to be stored in conditions that carefully balance temperature and humidity to maintain seed quality and reduce seed deterioration.
Mason jars and other glass containers are great options for seed storage so long as they are sealable. Ziplock bags, freezer bags and other plastic containers are also great options.
Increasing moisture content leads to reduced compression strength. Increasing moisture content also leads to paper swelling, whilst drying makes it shrink. As an example, between 0 and 90% RH, dimensions can change by 0.8% in the MD and 1.6% in the CD.
The proportion of water vapour in the air is called its humidity. The moisture-holding capacity of the air depends on its temperature. Higher the temperature, higher is the holding capacity. Hence, the Humidity is high in the Summer season.
The common rule of thumb is that the moisture holding capacity of saturated air doubles for every 20°F increase in temperature. Fifty degree air holds 0.0077 lb H2O/lb dry air which is slightly more than double the moisture holding capacity at 30°F, 0.0035 lb H2O/lb dry air.
Altered Ecosystem Structure: As temperatures increase and soil moisture changes, plant and vegetative zones are shifting in response. Trees are forced to migrate to higher elevations to find cooler, more suitable climates for their survival.
For example, raw cucumbers are over 96% water and melons are 92-94% water, while green lima beans con- tain approximately67% water and ripe avocados contain 65%.
If dried foods pick up moisture from the storage area, molds and bacteria can grow. This can lead to spoilage and illness. Moisture can also lead to the breakdown of some packaging materials (paper degradation and metal rusting). In areas of high environmental humidity a dehumidifier may be needed.
The moisture percentage present in food should be between 18% to 25% during food storage. The preservation methods like drying and freezing can prevent the moisture in the food.
A PRODUCT stored at too high a moisture content will deteriorate. It is therefore desirable to determine the moisture content of a product at different times, e.g. at harvest, during storage, and also on buying or selling where the risk of adulteration with water may be present if price differentials are in operation.
An acceptable level of indoor humidity is generally 30 to 50%, which prevents the growth of microorganisms, such as mold. Excess moisture promotes mold, mildew, fungi, bacterial growth, and possibly viruses. Contaminants can degrade the indoor air quality and cause health problems.
Generally speaking, for drywall, a safe moisture content (%MC) would be less than 1% MC. Anything above 1% MC in drywall would indicate a level of moisture that could compromise the integrity of the gypsum board. Exterior walls may use a variety of materials, from wooden siding, to vinyl, aluminum, brick, and stone.
Before storing the grains, they are properly dried under the sun to reduce the moisture in them. If freshly harvested grains are stored without drying, they may get spoilt or attacked by organisms, losing their germination capacity.
The maximum moisture content for warm-season storage is 13% to 14% for corn, 11% percent for soybeans, 13.5% for wheat, 12% for barley, and 8% for oil sunflowers. Mold growth will occur at summer temperatures if the grain exceeds the recommended moisture content.
Moisture in grain will gradually reduce germination ability of the seed during storage. Active respiration of the grain during storage will deplete the nutrition reserves that the seed uses to germinate or sprout. Molds and diseases can also reduce the ability of the seed to germinate.
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