Maintaining 'Marketable Quality' Even Under Extreme Heat: Fruit Vegetables Achieve 22% Average Yield Increase

AGRI SMILE Co., Ltd. (Headquarters: Chiyoda-ku, Tokyo; President & CEO: Takaya Nakanishi) announces the results of biostimulant validation trials conducted across 106 agricultural cooperatives (JAs), 69 crop varieties, and 1,500 hectares nationwide. Among fruit vegetables—including tomatoes, mini tomatoes, cucumbers, eggplants, and bell peppers—significant improvements were observed, including reduced off-grade produce and stable fruit setting, resulting in an average 22% increase in yield (※2).

With rising temperatures and increasingly unstable weather conditions affecting agricultural production across Japan, these results demonstrate that yield gains and quality improvements are achievable even under extreme heat, contributing to increased farmer incomes and more stable agricultural output.

※1: AGRI SMILE “Initiating Trial Introduction and Efficacy Verification of Biostimulant Materials in Accordance with MAFF Guidelines Across 100 JAs in 32 Prefectures” (July 2025) https://prtimes.jp/main/html/rd/p/000000046.000039438.html

※2: Yield increase rate calculated from the difference in yield between biostimulant-treated plots and control plots in each trial area, with the national average derived from these values.

## Background

According to the Japan Meteorological Agency, the average summer temperature (June–August) in 2025 was the highest since records began, marking the third consecutive year of record-breaking highs following 2023 and 2024. The number of locations recording temperatures above 40°C and the cumulative count of extreme heat days also reached all-time highs, significantly impacting agricultural production nationwide (※3).

Among the most affected crops are fruit vegetables such as tomatoes, mini tomatoes, cucumbers, eggplants, and bell peppers. High temperatures can lead to poor fruit set, flower drop, inadequate fruit enlargement, uneven coloring, and smaller fruit size—all of which directly affect market prices and farmer incomes. Additionally, market value is highly dependent on quality factors such as shape, size, color, and shelf life. Thus, the impact of rising temperatures extends beyond yield loss to include reduced profitability due to increased off-grade produce, price volatility, and challenges to stable supply.

In response, AGRI SMILE has collaborated with JA groups and local agricultural research institutions to scientifically evaluate biostimulant materials as a means to ensure stable production under climate change. In 2025, trials were conducted across 106 JAs, 69 crops, and 1,500 hectares, with cost-effectiveness confirmed in 80% of the 200 evaluated fields (※4).

However, cultivation challenges and desired outcomes vary by crop. For fruit vegetables, maintaining marketable quality under high temperatures—alongside yield stability—is critical to farm profitability. Analysis of nationwide trial data revealed multiple profitability-enhancing outcomes in fruit vegetables, including yield increases, reduced off-grade produce, and improved fruit set stability. Therefore, AGRI SMILE is now releasing findings focused specifically on fruit vegetables.

※3: Japan Meteorological Agency (September 2025) “Characteristics and Causes of the Record-Breaking Heat and July Drought in Summer 2025, and Atmospheric Patterns Behind the Early August Heavy Rainfall” https://www.jma.go.jp/jma/press/2509/05b/kentoukai_bessi20250905.pdf

※4: AGRI SMILE “Using Validation Data from 106 JAs, 69 Crops, and 1,500 Hectares, Cost-Effectiveness of Biostimulant Materials Confirmed in 80% of 200 Evaluated Fields” (December 2025) https://prtimes.jp/main/html/rd/p/000000052.000039438.html

## Fruit Vegetable Trials Overview

The results being released today summarize the outcomes of biostimulant trials conducted in 2025 across 106 JAs, 69 crops, and 1,500 hectares, focusing specifically on fruit vegetables such as tomatoes, mini tomatoes, cucumbers, eggplants, bell peppers, strawberries, watermelons, and melons.

### Nationwide Trial Overview

- Period: April–December 2025
- Regions: 32 prefectures nationwide
- Participating JAs: 106
- Target crops: 69 varieties
- Trial fields: 318 fields (total area: 1,500 hectares)

### Fruit Vegetable Trial Overview (This Release)

- Target crops: 16 varieties
- Trial fields: 70 fields

### Materials Used

The trials utilized two biostimulant products: “Heat Protect,” designed to enhance heat stress tolerance, and “Root Up,” aimed at improving nutrient uptake during the growing season. Both products are evaluated based on scientific data compliant with the Eco-LAB self-regulatory standards, including mechanisms of action and application conditions.

### Key Results

Among fields where yield could be assessed, biostimulant-treated plots showed an average 22% increase in yield compared to control plots.

- Tomato: Improved plant vigor, enhanced fruit enlargement → Average 12% increase (up to 16%)
- Mini Tomato: Improved plant vigor, reduced flower drop → Average 17% increase (up to 20%)
- Cucumber: Improved plant vigor, reduced female flower dieback → Average 29% increase (up to 69%)
- Bell Pepper: Improved plant vigor, reduced blossom-end rot → Average 36% increase (up to 48%)
- Eggplant: Improved plant vigor, reduced flower drop, enhanced fruit set → Average 25% increase (up to 61%)

Additionally, improvements contributing directly to profitability were observed, including reduced off-grade produce, suppression of flower drop and plant fatigue, and stabilized harvest periods due to sustained plant vigor. These results indicate that biostimulants help maintain both higher yields and marketable quality under high temperatures, supporting increased farmer incomes and stable supply chains for distributors, retailers, and the food industry.

This initiative has also been featured in ongoing advertising features in the Nihon Nogyo Shimbun (Japan Agricultural Newspaper). The nationwide trial overview was introduced in the February 4, 2026 edition (※5), and the fruit vegetable trial results were highlighted in the June 16, 2026 edition (※6).

※5: Nihon Nogyo Shimbun (February 2026) “Biostimulants: Protecting Yield and Quality Even in High Heat” https://www.agrinews.co.jp/advertisement/pr/index/133

※6: Nihon Nogyo Shimbun (June 2026) “Biostimulants: Boosting Profitability for Fruit Vegetables Even in Extreme Heat” https://www.agrinews.co.jp/advertisement/pr/index/146

### Voices from the Field

#### Fukushima Prefecture – JA Fukushima Mirai: Cucumber

An 81% reduction in female flower dieback—a major challenge under high temperatures—was confirmed. The biostimulant was used in combination with pesticides, leading to stable fruit set, reduced plant fatigue, and increased yields.

Comment:

“In fields treated with the biostimulant, leaf growth was vigorous, and there were days when yields more than doubled. While one truckload of harvest required 30 ares in the control field, only 15 ares were needed in the biostimulant-treated field.”

#### Kumamoto Prefecture – JA Kumamoto City: Eggplant

Suppression of heat damage and sustained plant vigor were confirmed. Stable growth continued until the end of harvest, enabling prolonged market supply.

Comment:

“In fields where Heat Protect was applied, transplant shock was eliminated at planting, and