Physiological droughtis the plant's inability to absorb water, even though the water is in the soil. The most commoncauses of physiological droughtare low temperatures (plants cannot absorb water from frozen ground) and excessive soil salinity. See how to recognizesymptoms of physiological drought , when this phenomenon occurs most often, and how to prevent physiological drought and help dry plants.
Pendulous rhododendron leaves. The effect of physiological drought
Fig. shutterstock.com
Symptoms of physiological drought
Plants suffering from water shortageare usually turgorless, have few leaves, yield poorly, wilt and die. Oxidative stress also results in yellowing, browning, drying and premature leaf fall. Characteristicsymptoms of physiological droughtare leaves in evergreen rhododendrons hanging down and curling into a roll (along the main nerve) or browning of conifers in early spring.
When does physiological drought occur?
Physiological drought occurs most often in 3 periods:
- In the early spring , when the soil is chilled (it may still be frozen) and the weather conditions have already started to favor transpiration (water evaporation from plant tissues). As a result of transpiration, the plant loses water and cannot replenish it from the frozen ground.
- During snowless winters , when dry winds and strong sunlight dry the plants. At the same time, plants cannot replenish water from dry or frozen soil.
- In autumnif there is not enough rainfall. In such a situation, plants are not able to accumulate water before winter.
Evergreen plants are most vulnerable to physiological drought due to low temperatures and freezing winds replenish water due to soil freezing.
The bark litter prevents the soil from drying out and freezing
Fig. shutterstock.com
Causes of physiological drought
The most common are3 causes of physiological drought :
- Too much soil salinitycaused, among others, by improper fertilization (too high doses of mineral fertilizers) or the use of s alt to maintain communication routes in winter.
- Dry, frozen soil and drying, cold windswith no snow cover. Frosty, snowless, and sunny winters and early spring are dangerous, when the sun is quite strong and the ground is dry or cold. Such conditions are especially dangerous for evergreen and coniferous plants, where the water transpiration from the green surface takes place all year round, and because the ground is frozen, they are not able to replenish its deficiencies.
- Soil hypoxia , occurring most often when the soil is too firm, loamy, with a low humus content.
The agrotextile cover protects against drying, frosty wind
Fig. shutterstock.com
How to prevent drought
To protect plants against the effects of physiological drought:
- Mulch the soil to reduce water evaporation from the substrate.A thick layer of mulchalso reduces the risk of soil freezing near the plant roots,
- Shade the plantswith non-woven agrotextiles or shading nets to protect them from winter sun, especially during snow-free, cold winters,
- Use moderate fertilization in accordance with the needs of plants, avoiding the use of excessive doses of mineral fertilizers. Instead of highly concentrated artificial mineral fertilizers, it is worth usingnatural fertilizers, such as e.g. bas alt flour. Minerals from rock flour are released very slowly, which effectively protects us against over-fertilization and soil salinity,
- Limit the use of road s altto winter maintenance of driveways, roads and paths adjacent to the garden. Instead of the popular sodium chloride, it is better to use magnesium chloride that is safe for soil and plants,
- Maintain the proper soil structuree.g. through appropriate organic fertilization,
- Plant plants inpositions sheltered from the wind ,
- Plant highly frost-resistant plantsand not very sensitive to soil salinity.
If our garden is exposed tostrong blasts of frosty, drying windduring the winter, it is a very good idea to use protective screens made of agrotextile. The screens are placed around the plants most susceptible to dryness. In this way, we protect plants against the wind, but at the same time we do not expose them to overheating, which sometimes occurs under a too thick layer of agrotextile.Instead of covering the plants as a whole, only a screen is set up to protect them from the side(e.g. from the side from which the wind blows). Therefore, it is an ideal solution for plants that are sufficiently frost-resistant but sensitive to physiological drought.
Hydrogels and TerraCott are helpful in preventing physiological drought . These are preparations that are mixed with the soil before planting the plants.The hydrogel contained in these preparations absorbs water from the soil and gives it back to plants at times when water is scarce. This reduces water consumption for watering and allows the plants to survive longer between waterings.
How to save plants affected by physiological drought
Plants suffering as a result of physiological droughtfirst of all it is worth watering abundantly. If a physiological drought affects evergreen plants suffering during snowless and frosty winters, watering should be done as soon as the thaw comes. Also in the case of soil salinity, watering may be helpful as it will flush the excess mineral s alts into the lower soil layers.
Plants affected by physiological droughtcan also be supported by using the growth stimulator SuperPlon K. This agent is used as a spray. The treatment restores vigor to plants and improves the circulation of juices in their tissues.It is perfect after frosts and for saving dry and wilted plants. It is such an energy boost for weakened plants.
In the case ofplants affected by physiological drought in winter , the rescue spraying with Superplon K is performed in spring, at the beginning of the growing season. This will stimulate the plants to start growing.
MSc Eng. Anna Błaszczak
