Bio stimulants-an Effective Solution for Abiotic Stress and Improved Crop Yield

Due to ongoing climate change, weather and seasons have become increasingly unpredictable, often leading to crop losses. Statistics show that 60% to 80% of crop yield losses are caused by abiotic stress; crop yields are high in good weather years and low in poor weather years. Bio-stimulants can effectively address these abiotic stress issues.

1. Bio-stimulants
Bio-stimulants are a class of substances and/or microorganisms that, when applied to plant leaves or roots, stimulate natural physiological processes within the plant, enhancing nutrient absorption, nutrient utilization efficiency, abiotic stress tolerance, and crop quality.  Their effects are relatively independent of their nutrient content.

Currently, globally recognized plant bio-stimulants fall into four main categories: plant-derived extracts (algae and plant extracts), microbial preparations, proteins, polypeptides, and free amino acids, and humic and fulvic acids. Some organizations also include chitosan and minerals.

These bio-stimulants have three main applications, depending on their specific effects and mechanisms: foliar spray, seed treatment, or soil application.

It's important to note that bio-stimulants are neither plant growth regulators nor pesticides, nor are they fertilizers. They cannot completely replace plant growth regulators, pesticides, or fertilizers; they are something in between:

They are not plant growth regulators, but they can induce the plant to produce endogenous hormones, enhancing its own stress resistance;

They are not fungicides, but they can induce plant resistance to fungal, bacterial, and viral diseases;

They are not fertilizers, but they can significantly improve the absorption and utilization of fertilizers by crops, resulting in higher yields and better quality.

This is the most outstanding characteristic of bio-stimulants.

2. Using Bio-stimulants

Bio-stimulants can address abiotic stress issues that pesticides and fertilizers cannot solve. So, how can they be used correctly and effectively?

We have always emphasized that the application of biological pesticides should focus on prevention, shifting from reactive to proactive use. The same applies to bio-stimulants.  We can divide the use of bio-stimulants into three stages: prevention, proactive treatment, and curative treatment. (1) Before abiotic stress occurs (prevention/sensitization stage): Use biostimulants to enhance crop stress tolerance.
(2) During the occurrence of abiotic stress (reactive/prophylactic treatment stage): Use biostimulants to further enhance crop stress tolerance and improve crop survival rates.
(3) After abiotic stress has occurred (treatment stage): Use biostimulants to improve crop growth and development.

The ultimate goal is to enhance crop nutrient uptake efficiency and stress tolerance by inducing physiological changes in plants or improving the rhizosphere environment, thus strengthening the crops and enabling them to better withstand abiotic stress. This approach also aims to reduce the use of chemical pesticides and minimize pesticide residue risks.


2.1  Before and During Abiotic Stress – Prevention and Response Stages

(1) Seed Treatment

Soaking wheat and corn seeds in a 0.1 mL/L and 1.5 mL/L solution of biostimulant, respectively, resulted in improved germination rate and uniformity compared to the control group.

(2) Pre-emptive Application and Soil Treatment

Drip irrigation with biostimulant was applied to cauliflower 21 days after transplanting. At harvest, the results showed that biostimulant-treated cauliflower had a more developed root system, higher yield, and more uniform growth, with an average yield increase of 1.15 tons per hectare (11% increase), and a return on investment of 16–35 times.

Applying biostimulant at concentrations of 0, 6, 12, and 25 kg/hm² to potatoes during drought stress delayed leaf dehydration and improved tuber number and size; the 25 kg/hm² concentration performed best.

Two months after two applications of biostimulant, banana plants showed significantly better growth compared to the control group.

(3) Foliar Spraying

Potato plants were sprayed with 4.5 L/hm² of biostimulant 5 days before cold stress. The plants experienced over 60 days of cold stress (including 6 frost events, with a minimum temperature of -3.6°C). At harvest, the biostimulant-treated potatoes showed a higher yield, larger tuber size, and more tubers.

Conclusion:  Whether applied through seed treatment, soil application, or foliar spraying, biostimulants can reduce crop damage, accelerate recovery, and minimize yield loss during and before abiotic stress.

2.2  After Abiotic Stress Occurs – Treatment Stage

After hail damage to corn plants growing in saline soil, a foliar application of 3 L/ha of a biostimulant was manually applied.  At harvest, yield was measured: compared to the control, the biostimulant-treated corn had higher yields (23% more ears per plant) and a higher marketable yield.

During a severe drought in Europe, potato plants on farms without irrigation systems suffered from drought stress.  Three foliar applications of 3 L/ha of biostimulant improved plant health, resulting in higher yields at harvest.

These experiments demonstrate that biostimulants can effectively mitigate the impact of abiotic stress on crops. Statistical analysis of extensive data shows that using biostimulants during the preventative stage (before abiotic stress) increases crop yield by 17%, compared to 11% during the stress event and only 8% after the stress event.

Therefore, the conclusion is that using biostimulants before abiotic stress (as a preventative measure) is more effective.  This maximizes the benefits of biostimulants and minimizes the negative impact of abiotic stress on crop yield.

Wheat experiments also confirmed this conclusion. Compared to the control, biostimulant application as a preventative measure increased wheat yield by 12.8%, while application after the stress event only increased yield by 7.3%.