Interaction of Microbial Consortium and Auxin to Enhance the Iron Uptake and Yield of Potato

Abstract

Globally, nutrition is an important factor to reduce the risk of prevailing diseases. Micronutrient deficiency affects more than 800 million people in the world due to the consumption of poor-quality food. The concept of green revolution although improve the yield, however, the quality of food was not considered. The agricultural sector has been responsible for feeding an ever-increasing population. For the betterment of human health, enrichment of micronutrient contents is vigorously required. Food fortification is the most common approach to mitigate micronutrient deficiencies. Biofortification of crop plants with desirable nutrients is an economical and well-accepted approach. The use of plant growth-promoting rhizobacteria is a promising, cost-effective, and sound option to mitigate micronutrient malnutrition. Microorganism helps in the mobilization of nutrients through different direct and indirect mechanisms, ultimately reducing the need of chemical fertilizers. However, information on the use of rhizobacteria along with plant growth regulator is quite limited to improve the iron content in crop plants. The current study involves sampling, isolation, screening, and microbial characterization of Fe-solubilizing and siderophore producing rhizobacteria and L-tryptophan for improving iron availability, potato growth, yield, physiological activities, and tuber characteristics. For this, several Fe solubilizing bacteria were isolated from potato rhizosphere from different pronounced areas of Punjab. The respective isolates were further tested for siderophore production, ACC deaminase, IAA, Catalase, Chitinase, Exopolysaccharides and P-solubilization. Later, the 11 best performing isolates were checked for their growth promotion potential in a growth chamber. Based on growth promotion, 3 isolates were selected and further tested for consortium development. Two isolates were found capable of consortium development through Venn streak and Line assay. Finally, two isolates alone, as consortium and in combination with L-tryptophan in the presence of different levels of iron were tested for potato growth promotion under pot and field conditions. The inoculation of bacterial isolates and plant growth regulators significantly improved the agronomic and physiological attributes of potato. However, the maximum response was observed through inoculation with microbial consortium and L-tryptophan. Potato tuber iron and phosphorous were significantly improved through the interactive effect of microbial consortium and auxin as compared with uninoculated control. Photosynthesis rate, transpiration rate, water use efficiency and tuber quality characteristics like starch content and moisture percentage were also improved significantly through inoculation with microbial consortium and auxin. The interactive approach of Fe-solubilizing siderophore producing bacteria and plant growth regulator (L-tryptophan) is an economical, cost effective, sound, novel, and environmentally friendly approach for improving growth, development, physiological attributes, and most importantly nutritional status of potato plant, which can help in combating micronutrient malnutrition especially in developing countries where poor people cannot afford to buy costly supplements.