Improving Drought Resilience

(Guest Blogger – Jemima McLeod)

Introduction

Drought is one of the most significant stresses facing agriculture; in this blog, we dive into the specific impacts on plants. When soil dries, plants activate a complex series of responses designed to conserve water and survive. However, these responses also reduce photosynthesis, increase oxidative stress and eventually cause tissue damage.

Understanding these processes helps explain how improving soil health and plant nutrition can increase drought resilience.

What Happens to Plants During Drought?

When plants detect dry soil, they produce the stress hormone abscisic acid (ABA). ABA signals the guard cells surrounding the stomata (microscopic pores on the plant leaf) to close, reducing water loss through transpiration.¹ The guard cells  then release stored potassium, which draws the water out of the cell, causing the guard cells to shrink and shut.

This protects the plant from losing more water, but it also restricts the entry of CO₂, limiting photosynthesis.

The plant can continue absorbing light energy even while photosynthesis is restricted, this can lead to the production of reactive oxygen species (ROS), which damage cell membranes, proteins and other cellular structures.²

As drought continues, the plant loses more water than its roots can replace. Cells lose turgor pressure, causing leaves to wilt and leaf temperatures to rise. Nutrient and ion balances can also become disrupted, creating additional stress.

Plants respond by producing osmolytes, sponge-like compounds that help maintain cellular water balance and protect proteins and membranes during dehydration.³

Under severe and prolonged drought, however, the plant increasingly redirects its resources away from growth and towards survival. Metabolic processes become disrupted and cellular damage can eventually become irreversible.

The result is a familiar progression:

wilting → increased leaf temperature → reduced photosynthesis → oxidative stress → cellular damage → plant death.

Building Drought Resilience Through Soil Biology

Improving the soil’s ability to retain and supply water can give plants a significant advantage, this is where biological products and organic amendments become particularly interesting.

Products such as vermicompost and vermiwash contain nutrients, organic matter and bioactive compounds that can influence soil properties and plant metabolism. Research has linked these inputs with improvements in:

• plant growth and yield
• photosynthetic activity
• root development
• enzymatic activity
• nutrient uptake efficiency
• tolerance to environmental stress

Rather than simply supplying nutrients, these products can help create a better environment around the plant roots.

How Vermiculture Products Can Help

Better Water Retention

Organic amendments (like NutriSoil Castings) and biostimulants (like NutriSoil Biological Solution) can improve soil structure and water-holding capacity. This means more water can remain available to the plant between rainfall events, delaying the onset of severe water stress.

Better soil moisture can also support stronger stomatal regulation and reduce the severity of wilting.

Improved Nutrient Availability

Drought can restrict nutrient movement and uptake because nutrients rely heavily on water movement through the soil.

NutriSoil products can provide nutrients such as nitrogen, phosphorus and potassium, while supporting biological processes involved in nutrient cycling.  Potassium is particularly important for drought resilience because it plays a major role in stomatal regulation, water relations and photosynthesis.⁴

Stronger Roots and Photosynthesis

Improved nutrient availability and soil conditions can support root development, allowing plants to explore more soil for available water.

Vermicompost (like NutriSoil Castings ) has also been associated with improved chlorophyll content, photosynthetic activity and antioxidant responses under stress.⁵

This means the plant may be better able to maintain productive functions for longer instead of rapidly switching into survival mode.

Reducing Stress

Independent testing by Microbe Labs Australia found that plants treated with 5 L/ha of NutriSoil Biological Solution produced lower levels of ABA (Abscisic Acid) compared with the control. The reduced ABA indicates that NutriSoil‑treated plants were experiencing less stress than untreated plants.

Proven Results

A trial was conducted on Tomato seedlings with and without Vermiwash (1:10 v/v) at different watering regimes (15, 30, and 45 mL of Hoagland’s nutrient solution) to evaluate the effect of water stress. In comparison with the control seedlings, Vermiwash treatment significantly improved stem thickness, leaf area, and shoot/root both fresh and dry weight of seedlings at 30 °C. At this temperature, Vermiwash-treated seedlings showed a significant increase for all examined physiological parameters (total chlorophyll, total sugars, and proline). Number of leaves, stem thickness, and shoot/root length and fresh weight of Vermiwash -treated tomato seedlings irrigated under a low watering regime were significantly greater than the control.⁵

Why Leaf Temperature Matters

Leaf temperature is an important indicator of plant water stress.

When plants lose water and stomata close, transpiration (which normally cools the leaf) decreases. The leaf can therefore become hotter.

Better soil moisture retention can delay this process, while adequate potassium supports the plant’s ability to regulate stomatal movement.

The result is a plant that can maintain better water status and avoid excessive increases in leaf temperature during drought.

Take-Home Messages

Drought resilience is not simply about giving a plant more water. It is about how effectively the plant can access, retain and use water while protecting its cellular processes.

When drought occurs, plants:

• produce ABA and close their stomata
• lose access to CO₂ and reduce photosynthesis
• risk increased ROS and cellular damage
• lose cell turgor and begin to wilt
• experience nutrient and ion imbalance
• produce osmolytes to protect cells
• eventually redirect resources from growth towards survival

Improving the soil before drought occurs can help plants manage these stresses.

Organic amendments such as NutriSoil Castings  can improve water retention, nutrient availability, root development and biological activity, providing plants with a stronger foundation for drought resilience.

As part of a holistic farming system, using NutriSoil Biological Solution can increase root development and microbial populations, leading to better nutrient cycling, more organic matter, and more diverse production of metabolites responsible for plant stress response.

Drought will always challenge plants. But by improving the soil environment and supporting plant nutrition and biology, we can help plants remain productive and resilient for longer.

Building drought resilience starts in the soil — before the leaves begin to wilt.

References:

1. https://www.ozbreed.com.au/why-is-drought-bad-for-plants/
2. https://www.sciencedirect.com/science/article/abs/pii/S2214786120300164
3. https://www.sciencedirect.com/science/article/abs/pii/S1878818125000234
4. https://www.mdpi.com/3684838
5. https://journals.ashs.org/view/journals/hortsci/49/9/article-p1183.xml
6. https://www.researchgate.net/figure/Long-and-short-term-responses-of-plants-to-drought-stress_fig1_348208107