Shade netting is one of the simplest methods to shield plants from excessive heat, especially for vegetable crops. The damages caused by excessive heat have become an increasingly significant issue in agriculture due to the evident climate changes happening on our planet. Rising temperatures and prolonged periods of drought are apparent to everyone.
In this article, we explain the conditions and damages that excessive and prolonged summer heat can cause to crops. We’ll also explore techniques to defend against such heat using specific agronomic methods and the use of suitable shading net.
The Problem of Excessive Heat
Cornfield suffering from intense heat
Shade netting is the solution to one of the most pressing issues in agriculture, intense heat. The ambient temperature is a critical factor for proper plant growth, and for vegetable crops, it significantly influences productivity.
Each plant species has an optimal growth temperature in its DNA. Temperatures below or above this range cause stress or even halt growth.
We’ve previously discussed plant freezing stress. This is generally caused by exposing crops to temperatures below their freezing point. With heat stress, the opposite occurs. In essence, exposing the plant to temperatures above its maximum growth temperature for an extended period causes varying degrees of stress. This stress is often coupled with water stress, meaning reduced water availability. Naturally, this issue is particularly pronounced during the summer months, such as July and August.
Temperature Ranges
Most plants can survive within a temperature range of 0 to 40 °C. Tropical and subtropical species are exceptions, withstanding temperatures approaching 50 °C.
Regardless of survival capacity, the ideal growth range is between 22 and 30°C, especially during vegetative and flowering stages. Stress conditions start occurring beyond this range. Up to 30 °C, the plant’s photosynthetic efficiency increases proportionally, but it decreases dramatically as heat increases.
Ambient temperature has a significant impact on the fluidity of cellular membranes. These plant components normally exhibit a liquid-crystalline phase that enables the movement of membrane proteins within the phospholipid bilayer. This facilitates regular ion and molecule exchange across cells.
Elevated temperatures increase membrane lipid fluidity, leading to loss of physiological functions in plant cells.
With high temperatures, the usual photosynthesis mechanism can’t replenish carbon used as a substrate for respiration. This leads to reduced carbohydrate reserves and loss of sugar content in fruits and vegetables.
In nature, plants employ defense mechanisms to overcome thermal stress. The plant can activate special metabolic pathways, decreasing the synthesis of regular proteins while rapidly increasing specific proteins known as heat shock proteins (HSP). These help plant cells endure heat stress.
Problems arise when this stress persists over an extended period. Unfortunately, this has become increasingly common in recent years and causes severe damage.
Common Heat-Related Damages
Pepper scalding
After understanding the conditions that lead to thermal stress, let’s delve into the most common damages to plants.
Firstly, there’s the wilting of plant vegetative organs, which can degenerate into irreversible withering.
Another typical damage caused by thermal stress is leaf curling.
Necrosis can begin to appear on leaf margins, along with yellowing. If the heat is intense, the yellowing can escalate into actual scorching, leading to leaf desiccation.
Even more concerning are damages to fruits, primarily resulting in sunburn on the most exposed parts.
Vegetable crops most sensitive to this kind of damage are undoubtedly peppers and tomatoes.
The damage appears as scorching on the fruit, rendering it unsuitable for sale.
Even some fruit trees are affected, as their skin is delicate. Apple, pear, and peach trees are at risk. In addition to scorching, these fruits can experience pulp vitrification.
Plant Protection with Shade Netting
Shade netting
The simplest method for protecting plants from excessive heat in home gardening is using shade netting.
These classic nets have sufficiently wide mesh sizes to allow air circulation while shading the area. They protect plants from sunburn and other heat-related damages. The shading effect from these nets also reduces air temperature, further safeguarding the field.
This method is easily applicable to home gardens and balcony or terrace gardens as it’s easier to find support structures to position the shading net. It’s important to leave the protected area open on the sides and focus on covering the top.
These nets also provide protection against adverse weather conditions like hail and heavy rain. Often, shade netting is referred to as anti-hail netting, addressing yet another atmospheric phenomenon that threatens our crops.
Given the increasingly unstable summer weather, using such nets has become necessary. This prevents issues like lodging and leaf damage. Shade nets are readily available on the market, such as available here.
Other Agronomic Remedies
Natural mulching on a pepper field
There are other useful agronomic techniques to shield plants from summer heat, which can complement shade netting. One significant approach is using natural mulching. By enhancing soil freshness, it limits water evaporation, ensuring greater soil moisture.
Another agronomic remedy involves proper irrigation management. If you’re fortunate to have a drip irrigation system, strategically regulate water supply during the hottest periods. Start by irrigating in the cooler hours, preferably early morning. Avoid excessive watering to compensate for shortages. Maintaining a consistent regime prevents dangerous waterlogging that can lead to other physiopathies.
Finally, another agronomic technique to protect against heat is hilling. We’ve discussed this operation when talking about winter crops like fennel and cauliflower. Hilling keeps the plant base cooler and encourages the growth of lateral roots, beneficial during high-temperature periods.
