Investigation of biopolymers for plant seed attachment on substrates in microgravity

Plant cultivation in unusual environments is a relatively new field of research, driven in particular by planned space missions. Besides light, magnetic and gravitational conditions also influence plant growth. Especially the effect of gravity on roots and shoots has been investigated. Such experiments can be conducted using a clinostat to simulate microgravity, which rotates slowly, typically at about 1 rpm, around a horizontal axis [1]. In clinostat experiments, the constant rotation prevents plant growth in open-soil systems. Instead, various substrates can be used, such as foams or textiles. However, placing seeds on these substrates still causes them to fall off during the clinostat’s rotation or to become separated from the substrate in space, respectively. Furthermore, the moisture required for seed germination cannot be maintained well in many textile substrates, which limits the substrate selection.

Various biopolymers, mainly konjac gum and alginate, were used to anchor seeds to a textile substrate, focusing on water retention and seed growth. The environmental conditions (temperature, relative humidity, irrigation and illumination) were varied between different experiments. The growth of three edible plants on different textile substrates, with and without a biopolymer coating, was compared.

The results show that the biopolymers investigated, particularly konjac gum, are well-suited for fixing seeds to textile and other substrates and can thus be used for experiments in simulated microgravity, i.e. on a clinostat, or in space. In addition, especially the konjac gum coating led to germination of all seeds on the second day, followed by samples with alginate coating, while seeds on pure fabrics started germination after approximately 4-5 days. Compared to arugula and radishes, the cress has grown very well, as expected.

[1] Malczyk, M.; Blachowicz, T.; Ehrmann, A. Coupled system of dual-axis clinostat and Helmholtz cage for simulated microgravity experiments. Applied Sciences 2024, 14, 9517.