Matthews, Stella
Ali, Asgar http://orcid.org/0000-0003-0552-7322
Siddiqui, Yasmeen
Supramaniam, Christina Vimala
Article History
Received: 28 November 2021
Accepted: 14 March 2022
First Online: 29 March 2022
Declarations
:
: Most of the well-established commercial products were derived from seaweeds, beneficial microorganisms and humic acids as a stand-alone product. Rarely could find bio-stimulant products comprising of two or three sources. It is well understood that one single source might not have the maximum effect on plant growth, health, quality or yield. The response of the plant to a combination of good bio-stimulant sources need to be investigated further. Therefore, new formulations for bio-stimulant products are a paramount concern as it shall produce more benefit to various crops in terms of enhancement of plant health and productivity under biotic and abiotic stresses as well as replenishment of soil health. Encapsulation of bio-stimulants using biopolymers could improve its shelf-life and reduce the direct impact on its environment. This is another important criterion that needs to look into, where non-toxic and biodegradable biopolymers with bio-stimulant characteristics could be an added advantage in its formulation. Besides, other promising substances such as chitosan nanoparticles, nano-silicon, microalgae and medicinal plant extract that have not been widely explored in the production of bio-stimulants can be addressed in the future. In the past, researchers have not dealt with the method of application in much detail. The bio-stimulant application method would determine its success in terms of its practicality and feasibility. The formulation, time or stage of application and method of application should be cost-effective to make it affordable for farmers. Pros and cons of seed priming, foliar application, soil drenching and hydroponics usage of bio-stimulant need to be detailed out including its formulation, shelf-life, stability, upscaling feasibility, production costing, impact on the plant–soil system and agriculture viability. Since plants have been reported to respond both positively and negatively to bio-stimulant sources, especially nano-silicon, thorough research on the response under field experiments using multiple crops, multi-seasonal experiments and multi-geographical location need to be carried out. Recyclable and safe natural materials also need to be explored further to produce diverse bio-stimulant products. Although nanoparticles derived from organic and natural substances are deemed to be safe, toxicity studies towards plant and soil microbiome are inevitable. The thorough and long-time effect of nanoparticles on soil and plant microbiome, heavy metal accumulation and nutrient levels need to be studied with advanced tools such as genomics, proteomics, metabolomics and ionomics to get an insight into its interrelationships, mechanisms, impact, advantages and disadvantages.The mechanisms of each bio-stimulant component need to be investigated to get a holistic view of the physiological changes caused by bio-stimulant to soil and plant. Most of the studies have been reporting the effect of bio-stimulant at the seedling level. Very little research has been reported on the effect of bio-stimulant on the physiology and biochemistry of mature plants, soil microbial community and soil fertility. The future for the bio-stimulant product for crops is very promising due to its great advantages to boost the health, quality and yield of crops under stresses caused by climate change. Therefore, innovative and diverse bio-stimulant products are crucial for sustainable crop cultivation.No funding was received to assist with the preparation of this manuscript.
: The authors have no relevant financial or non-financial interests to disclose<b>.</b>