Biochar has been studied as a potential substitute for phosphate fertilizer, and it is produced through biomass pyrolysis at temperatures between 400°C to 700°C. Different organic feedstocks such as waste wood, chicken manure, or leaves can be used to create biochar-based fertilizers. However, past research shows that plants' responses to biochar vary, with some growing better, some showing no fertilization effects, and others being adversely affected by the biochar fertilizer.
Researchers from the Joseph Gottlieb Kölreuter Institute for Plant Sciences and the Institute for Technical Chemistry conducted a study using tomato seedlings to investigate the impact of different biochar biomass sources on their symbiosis with arbuscular mycorrhizal fungi (AM fungi) in the soil. In the initial experiment, they compared biochar derived from wheat straw and chicken manure. The chicken manure biochar contained nine times more phosphate, a crucial molecule for plant growth, and as expected, tomato seedlings fertilized with chicken manure biochar exhibited rapid and robust growth due to the abundantly available phosphate.
Symbiosis Between AM fungi And Tomato Plants Investigated Researchers
In a second experiment, researchers investigated the symbiosis between tomato plants and arbuscular mycorrhizal fungi (AM fungi), which have been living in the roots of 80% of land plants for over 400 million years. AM fungi colonize the plant roots, absorbing phosphate from the soil and transferring it to the plant in exchange for sugar and lipids. The researchers observed that chicken manure-based phosphate-rich biochar hindered this symbiosis, leading to a limited molecular exchange between the plant and fungi. On the other hand, wheat straw-based biochar promoted an active symbiotic relationship, making the plants more compatible with other microorganisms and providing better protection against pathogens. The complex molecular response of the plants to the biochar was unexpected.
Unraveling Plant Responses: Gene Expression Analysis Offers Insight into Phosphate Efficiency and Fertilizer Reduction
The team employed gene expression analysis to validate these findings. Although this method is intricate and costly, it allows them to observe the plant's genetic activity and identify specific markers that are activated or suppressed. Further experiments will be necessary to gain a deeper understanding of how plants respond. Professor Requena emphasizes that once they decipher this response, they can potentially engineer plants to require less phosphate and, consequently, reduce their reliance on mineral fertilizers in the future.
