How Calcium and Nitrogen Affect Strawberry Size and Firmness

Greg Howard
21st July, 2024

How Calcium and Nitrogen Affect Strawberry Size and Firmness

The visual classification of strawberry (Fragaria × ananassa) fruit into four distinct growth stages, from green to over-ripe, provided the developmental framework for analyzing the effects of calcium and nitrogen treatments on the fruit's cellular structure and mechanical strength.

Image adapted from: An et al. / CC BY (Source)

Key Findings

  • The study conducted in Potsdam, Germany, found that strawberries treated with nitrogen had larger cell sizes compared to those treated with calcium
  • Strawberries with larger cell sizes were more susceptible to mechanical damage, leading to higher rates of bruising and decay
  • Incorporating cell size data into simulations improved the accuracy of predicting strawberry tissue compression, which can help reduce food waste
The study conducted by the Leibniz Institute for Agricultural Engineering and Bioeconomy[1] addresses a significant issue in the agricultural sector: the decay of strawberry fruit due to bruising, which leads to substantial food waste. This research aims to understand the mechanical properties of strawberries by examining the effect of cell size distribution on the fruit's susceptibility to damage during compression. Strawberries are known for their delicate texture, which makes them highly perishable[2]. Previous studies have shown that the cell size distribution in strawberries can vary widely, and this variation influences the fruit's mechanical properties. For instance, a study using laser light scattering density (LSD) analysis revealed that the cell size of different strawberry cultivars ranged from 30 to 500 µm, with a frequency peak between 200 and 240 µm[2]. This variation in cell size was correlated with the fruit's mechanical properties, such as failure stress and elastic modulus. In the current study, researchers applied LSD analysis to investigate the effect of cell size distribution percentages on the mechanical properties of strawberries across three growth stages. They also examined the impact of foliar spray applications of calcium (Ca), nitrogen (N), and a combination of both (Ca-N). The growth rate (k) for cell sizes ranging from 300 to 450 µm was found to be higher in strawberries treated with nitrogen compared to those treated with calcium, with values of 0.8 and 0.5, respectively. The study further compared cell sizes and mechanical properties of the fruit tissue, revealing a strong correlation between cell size and fruit mechanics. Based on the cell size data, researchers established discrete element models (DEM) using a simple contact model of Hertz-Mindlin to simulate the compression peak force of strawberry tissue. The comparison between measured compression data and DEM simulation showed a significant reduction in mean square error when LSD percentages of cell size distribution were considered. For example, in the Ca-treated group of over-ripe fruit, the error was reduced from 9.6% to 6.5%. This research builds on earlier findings that identified the role of cell size distribution in influencing the mechanical properties of strawberries[2]. By incorporating cell size data into DEM simulations, the study provides a more accurate representation of fruit tissue compression under various environmental growth conditions. This enhanced simulation accuracy is valuable for several applications, including plant nutrition, the development of robotic harvesters, sorting devices, and the assessment of the shelf life of fresh fruit. Moreover, the study's findings have implications for the nutritional and therapeutic benefits of strawberries. Previous research has highlighted the health benefits of strawberries, which are rich in phytochemicals and vitamins that contribute to their antioxidant capacity and potential to mitigate chronic diseases[3]. However, these bioactive factors can be affected by differences in strawberry cultivars and agricultural practices. Understanding the mechanical properties of strawberries and how they are influenced by cell size distribution and nutrient treatments can help optimize agricultural practices to retain these bioactive compounds. Additionally, the study ties into the broader context of strawberry fruit development and ripening. The plant hormone abscisic acid (ABA) has been suggested to play a role in the ripening of strawberries, with genetic studies identifying the FaPYR1 gene as a positive regulator of this process[4]. By understanding the mechanical properties of strawberries and how they are influenced by cell size distribution, researchers can gain insights into the factors that affect fruit ripening and quality. In conclusion, the study conducted by the Leibniz Institute for Agricultural Engineering and Bioeconomy provides valuable insights into the mechanical properties of strawberries and how they are influenced by cell size distribution and nutrient treatments. By incorporating cell size data into DEM simulations, the research enhances the accuracy of fruit tissue compression models, which has practical applications in agriculture and food science. These findings build on previous research and contribute to a better understanding of the factors that affect strawberry quality and shelf life.

FruitsAgricultureBiochem

References

Main Study

1) Relationship of Cell Size Distribution and Biomechanics of Strawberry Fruit Under Varying Ca and N Supply

Published 20th July, 2024

https://doi.org/10.1007/s11947-024-03491-0

Related Studies

2) Effect of cell size distribution on mechanical properties of strawberry fruit tissue.

https://doi.org/10.1016/j.foodres.2023.112787

3) Strawberry as a functional food: an evidence-based review.

https://doi.org/10.1080/10408398.2011.608174

4) FaPYR1 is involved in strawberry fruit ripening.

https://doi.org/10.1093/jxb/err207


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