Calcium & Environmental Stresses: Heat

Hot weather is hard on people – when we get too hot, we get uncomfortable, we are not as productive, and in severe cases, can suffer significantly. Plants, just like humans, suffer when it is too hot. Heat stress impacts several key processes in plants leading to reduced crop yield and quality.

Just like humans, plants have mechanisms to deal with heat stress. Calcium plays a critical role in many of the mechanisms that plants use to deal with heat stress. 

heat stress diagram.PNG

Research on tomatoes shows that Ca helps protect tomato plants from heat stress. Heat stress damages plants by what is called “oxidative stress” which is due to the production of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and the oxide ion (O2-). These ROS compounds damage plant membranes, proteins, and RNA and DNA. Calcium application to tomatoes reduces the formation of these two key ROS species and reduces the damage from heat stress.

heat stress graph H2O and Ca.PNG

Severe heat stress can lead to plant injury and even death. This figure below shows the benefit of supplying supplemental calcium to young Brassica seedlings when the seedlings are subjected to 104°F heat stress. Almost all the seedlings that did not receive supplemental Ca died while almost all the seedling that received supplemental Ca survived.

heat stress graph seedling survival.PNG

Humans sweat and the evaporation of water from skin cools us. Thus, our body temperature is 98°F when the air temperature on a hot day may be 108°F. In a similar manner, plant leaves transpire and the evaporation of water cools the leaf. Leaves that are transpiring water are usually several degrees cooler than the air around them. Calcium, along with potassium, regulates the opening and closing of the guard cells around the stomates in leaves. Plants that lack sufficient Ca lose the ability to regulate the stomates and plants can become overheated, leading to injury and death.

In addition to the direct beneficial effects of calcium on heat stress, calcium also plays a key role as part of the messenger system in plant by signaling the heat stress and triggering plant responses to heat stress.


Potato is a cool-season crop that is grown in areas where the summer temperatures often exceed 100°F. Research in controlled environment chambers clearly shows the benefit of Increasing the concentration of soluble calcium in the nutrient solution.

stomates illustration.PNG


Benefits of YaraLiva® Calcium Nitrate

How do you ensure that your crops have all the calcium they need to manage heat stress? YaraLiva Calcium Nitrate is the ideal choice to provide your crop with calcium.

Fertilizers like YaraLiva CAN-17 or CN-9 have typically been used early in the spring to provide crops with readily available nitrate-N when soil and air temperatures are cool. However, the soluble calcium in YaraLiva CAN-17 and CN-9 also plays a key role in helping crops overcome environmental stresses such as heat, water, salinity, and sodicity. YaraLiva products are part of a season-long fertilizer program that supports optimal yield and quality.



YaraTera® NITRAKAL™ MAX1 provides a balanced supply of nitrate-nitrogen, potassium, and calcium. YaraTera Nitrakal Max is ideal for applications by fertigation during peak demands in the weeks of heat stress to support stomatal function.


Total Nitrogen (N) 9.0%

       - Nitrate N (NO3) 6.8%

       - Ammoniacal N (NH4) 2.2%

Soluble Potash (K2O) 7.0%

Calcium (Ca) 9.5%


Patricia Dingus
Patricia Dingus
Regional Sales Manager

Central Coastal California

Eddie Muro
Eddie Muro
Sales Agronomist

Central Coastal California

sebastian korob
Sebastian Korob
Regional Market Development Manager
david morgan
David Morgan
YaraVita Specialist

South Central Valley, California