Łangowski et al., (2022) Plant Physiology and Biochemistry, 179 (49-57)
Investigation of the direct effect of a precision Ascophyllum nodosum biostimulant on nitrogen use efficiency in wheat seedlings
https://www.sciencedirect.com/science/article/pii/S0981942822001206
Summary
Wheat plays a critical role in global food security, providing approximately 30% of the calories consumed by the world’s population. However, to ensure its rapid and robust growth during the early stages, wheat requires a substantial amount of fertilizer application. Our scientific researchers have been dedicated to gaining a deeper understanding of the mechanisms behind our biostimulant, PSI®362, with a specific focus on its effects in agronomic applications on wheat. In their investigations, they have carefully examined the influence of various factors, such as the dosage of PSI®362, the timing of its application, and how it interacts with different levels of nitrogen (N) supplementation. The primary objectives of their studies have been to assess the impact of these variables on the growth dynamics of wheat seedling biomass, the uptake of nitrate, the production of N assimilation products, and the differential expression of genes associated with nutrient use efficiency (NUE). By examining these aspects, we aim to provide valuable insights into optimizing the use of PSI®362 in agricultural practices.
In the following assays, wheat seedlings were cultivated in the absence of a soil microbiome. The concentration-dependent assay aimed to evaluate the potency of PSI®362 at three different doses (5mg, 10mg, and 50mg).
The results revealed a positive correlation between the dose of PSI®362 and the increase in shoot (5.7%, 11.7%, 33.6%), root (18.6%, 36.3%, 142.2%), and overall plant (10.7%, 17.7%, 66%) biomass. Additionally, the concentration-dependent assay demonstrated that PSI®362 supplementation led to an observable increase in plant nitrate levels. The lowest dose (5mg) effectively enhanced plant nitrate by 31.7%, while higher concentrations (10mg and 50mg) resulted in greater improvements of 48.9% and 89.9% respectively.
Furthermore, the combined application of high and low doses of PSI®362 resulted in a notable increase in the accumulation of soluble proteins and photosynthetic pigments. These findings strongly indicate that PSI®362 induces nitrogen uptake in a concentration-dependent manner, highlighting its potential as an effective biostimulant for wheat crops.
In the subsequent assay, wheat seedlings were cultivated under varying nitrogen (N) conditions, specifically in reduced N media (1/10xMS) compared to standard N media (1xMS). Remarkably, the combination of reduced N media and the application of the biostimulant resulted in significant increases in plant biomass (63.9%), shoot biomass (32.1%), and root biomass (132.6%) compared to the control group.
Notably, PSI®362 exhibited a stimulating effect on N uptake, even in the presence of reduced N media. This indicates that PSI®362 has the potential to enhance the plant’s ability to assimilate and utilize nitrogen efficiently, even under nutrient-limited conditions. These findings underscore the promising role of PSI®362 as a valuable tool in optimizing plant growth and productivity, particularly in environments with reduced nitrogen availability.
Continuing with the study, we examined the impact of the biostimulant on the time-dependent response of seedlings to PSI®362 over a period of 9 days. The results revealed a gradual and consistent increase in both total biomass and nutrient use efficiency (NUE) compared to their respective control groups. Specifically, the total biomass exhibited an incremental growth of 21.7% at day 3, 44.3% at day 6, and 39.3% at day 9 in comparison to the controls.
Furthermore, it was observed that the presence of PSI®362 coincided with a quicker decline in nitrate levels within the growth media, which correlated with an enhanced biomass accumulation in the treated plants. These findings suggest that PSI®362 not only promotes plant growth over time but also influences the nitrogen dynamics by accelerating nitrate utilization.
PSI®362 exerts a significant influence on the expression of genes associated with nitrogen (N) uptake, transport, and assimilation processes. The intricate process of N assimilation involves multiple steps that transform N compounds into essential amino acids and proteins, facilitated by a series of activated enzymes. PSI®362 demonstrates its effectiveness at each stage of the N uptake, transport, and assimilation processes, influencing multiple points within the pathway. Importantly, PSI®362 has shown to dysregulate nitrate-related genes and subsequently increase in nitrate assimilation products, contributing to an enhanced nitrate uptake capacity. This effect is achieved through the activity of protein transporters located in the plasma membrane of existing roots. By modulating gene expression and facilitating nitrate uptake, PSI®362 plays a crucial role in optimizing the plant’s ability to acquire and utilize nitrogen efficiently.
When compared to other commercially available biostimulants derived from Ascophyllum nodosum, PSI®362 exhibited superior effects on various agronomic parameters. Notably, PSI®362 demonstrated greater accumulation of nitrate, a higher increase in shoot and root tissue, and overall increase in plant biomass, compared to the competitor. Moreover, the application of PSI®362 resulted in an increase of approximately 10-15% in the levels of soluble proteins and photosynthetic pigments compared to the other biostimulants.
In summary, PSI®362 has consistently demonstrated positive effects on various aspects of plant growth and nutrient utilization in wheat seedlings. It has been observed to significantly increase plant biomass, promote nitrate accumulation, and influence the regulation of genes associated with nitrogen use efficiency (NUE). These findings strongly support PSI®362 efficacy as a biostimulant that enhances NUE in wheat seedlings. The proven mode of action (MOA) underlying these effects further confirms the suitability of PSI®362 as a valuable biostimulant for optimizing nutrient utilization and improving crop performance.
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