Protein-rich crops: Growing soybean in vertical farms

Added on 15 March 2022

Tags

Protein-rich crops: Growing soybean in vertical farms

Not all crops are created equally: some are simply more nutritious than others. What is the best way to grow these crops and how can we make them even more nutritious? The BU Greenhouse Horticulture of Wageningen University & Research investigated the production of protein-rich crops in their Vertical Farm.

Why should we focus on protein-rich crops?

We are starting to shift towards a more sustainable model for protein production and consumption, also known as the "protein transition". There is a growing concern for the environmental footprint and ethics of excessive animal protein production. Hence, there is a growing interest finding alternative, sustainable ways to produce proteins and exploring viable business models. The production of protein-rich crops in controlled environment agriculture is currently still in its infancy and viable business models have not yet been established. Therefore BU Greenhouse Horticulture initiated this experiment as a pilot study.

How do you select which crops to grow?

Protein-rich crops would require a high productivity and nutritious content to be viable across markets and production systems. Candidate crops were identified for their potential protein quality and quantity. These crops included for example Leguminosae and other new and 'forgotten' vegetables. Crops were finally selected for a high harvest index and yield, as well as a compact crop height and growing cycle. Furthermore a high Digestible Indispensable Amino-Acid Score (DIAAS) was taken into account an used as protein quality indicator. It provides an accurate measure of the amounts of amino acids absorbed and the protein's contribution to human amino acid and nitrogen requirements of the human body.

Soybean (Glycine max) was considered the most promising candidate: it features the highest protein content and quality, offers a broad spectrum of interesting products, and has the most available reference data.

Why should we grow soybean in a controlled environment?

Traditionally soybean is cultivated in the field, mainly in Brazil and the United States of America. Controlled environment agriculture (CEA) can improve the production of essential amino-acids in the cultivation of protein-rich crops. Greenhouses and vertical farms are already being used to produce highly nutritious crops with improved functional ingredients (e.g., minerals, vitamins). The production in CEA offers the opportunity to optimise production, improve crop protection, decrease land area used and potentially steer crop physiological mechanisms, provided there is sufficient understanding of crop response to the environment.

How do you steer a protein-rich crop?

There is currently little knowledge on the effect of plant growth conditions on protein quantity and quality. The compounds of crops are typically steered using light intensity, light spectrum, daylength, temperature treatment and nutrition. In order to see whether it is possible to steer protein quantity and quality in soybean, a light treatment (low Red:Blue ratio) and a temperature treatment (low temperature) were compared to a reference treatment. The design of the treatments for two cultivars (Viola and Obelix) was based on literature research. To check the effect of the treatments, the cultivation cycle of the soybean cultivars was closely monitored. The protein content of the beans was measured on four instances, in order to determine the rate of protein content accumulation during early reproductive stage of the pods. The protein quality was also tracked by measuring the amino acid composition of mature seeds.

How could we steer more swiftly and precisely?

Our ability to steer the nutritional quality of the crop is restricted by our ability to measure the plant physiology and specifically the protein content in vivo. The chemical analysis of protein content takes produce, time, money and energy. In this project we worked on a spectral measurement method that can accurately predict the protein content in soybean, based on the spectral characteristics of the pod. Not only does this method circumvent long-term reliance on slow chemical analysis methods, it also circumvents any form of destructive sample preparation by measuring directly on the pod. These measurements are rapid (1-10 seconds) and do not require technical experience. This would make the technique perfect for implementation directly in the production cell without need for harvesting.