Meeting the food demands along with nutritional security, without exploiting the natural resources is the biggest challenge that we are facing today. It is necessary to adopt alternative strategies that enhance resource use efficiency, without damaging the environmental quality.
Indian agriculture is facing big challenges in terms of depleting soil organic matter, imbalance in fertilizer use, emerging multi-nutrient deficiencies particularly of secondary and micronutrients, declining nutrient use efficiency, negative soil nutrient balance, etc. As all these problems can be well linked with fertilizer application in soil, the issues becomes more stringent when farmers pay double prices for these energy related inputs, viz., fuel and fertilizers. It’s high time to change our production plans with new energy conservation methods substituting the existing energy intensive and costly production system.
The increasing demand of qualitative and varietal foods by the consumer society demands energy production. Utilisation of that energy in a judicious manner for sustainable management of resources is a big challenge in the future. The depleting resources warrant farming communities to adopt alternative strategies to enhance the input use efficiency as well as the environmental quality.
Adaptability of microbes to thrive in different environments has attracted scientists to introduce microbial intervention in the agricultural processes. Bio-priming has the potential to fulfil many objectives of the modern production system with the use of beneficial microorganisms in an eco-friendly manner.
The technique
Bio-priming is a technique of biological seed treatment combining a variety of physiological and biological aspects related to seed and plant growth promotion together in one process (Fig.1). A controlled seed hydration is carried following beneficial microbial seed inoculation under warm and humid conditions. Microbial coating of seeds is done by taking eligible species of fungi and bacteria such as Trichoderma, Pseudomonas, Bacillus, Rhizobium, Azospirillum, Glomus, Azotobacter, Agrobacterium, etc. During seed imbibition, partial germination is allowed which triggers numerous physiological and biochemical processes (cell repairment, metabolism of reserves, DNA repairment, protein synthesis, ROS detoxification) in seeds, and before the emergence of plumule and radicle, the water treatment is terminated.
Bio-priming is an advanced seed treatment process in this era to empower the plants function effectively in all conditions. The bio-innovative system will work as growth enhancer, disease controller, and quality maintainer along with increased production. The performance of bio-primed seeds is noticed under diverse agroecological systems because of rapid germination, uniform seedling emergence, reduced seed dormancy, improved nutrient uptake, and greater tolerance to environmental stresses (pests and diseases).
Field experiment
Farmers of Indo-Gangetic Plains of Uttar Pradesh are involved in seed bio-priming before sowing for numerous crop species including rice, wheat, maize, and pulses. However, seedling bio-priming is recommended for vegetables (cabbage, cauliflower, or brinjal). A high nutrient requiring crop (N:P2O5:K2O @ 120:60:60kg ha-1), viz., red cabbage was selected for bio-priming. Healthy seedlings were transplanted in 4 × 2 m2 plots at a spacing of 50 cm × 50 cm. Three priming agents (Trichoderma harzianum, Pseudomonas fluorescens, and Bacillus subtilis) singly and in combination were used with 75% recommended dose of fertilizers (NPK). Field experiments were conducted at Vegetable Research Farm, Banaras Hindu University during rabi seasons of 2016 and 2017.
Results
Bio-priming enhanced the nutrient uptake of red cabbage crop both in terms of macronutrient (N, P and K) and micronutrient (Fe, Mn, Zn and Cu). Based on the nutrient content (N, P and K), combined application of T harzianum and P fluorescens resulted in highest N%, whereas combined application of P fluorescens and B subtilis resulted in highest P% and K% (Table 1). Microbial consortium performed better than single species priming. However, dual consortium surpassed triple consortium. Economical yield and energy use efficiency was higher in bio-primed treatments. These might be due to increased microbial activity in soil releasing enzymes, hormones and organic acids. The growth of primed plants was higher than non-primed plants. Rhizospheric interactions due to bio-priming have modulated the root architecture of crop, mobilized nutrients and improved the nutrient use efficiency. Strategic nutrient management has expedited the process of mineral element acquisition by plants from the soil.
Conclusion
Growing concerns among public about thoughtful health hazards (both environment and human) urge the requirement of eco-friendly, economical, and sustainable agriculture. Bio-priming is a simple tool that can be adopted even by small farmers. These sort of interventions besides reducing the level of fertilizer application will also improve the nutrient use efficiency of crops. Also, the use of agrochemicals is uneconomical leading to ecological disruptions. Pre-treatment of seeds with microbial agents has enormous potential in modern times. Selective use of microbes for specific purposes can further yield in high results. Bio-priming must therefore be integrated in to the existing technology of integrated nutrient management to achieve sustainable yields in agriculture.
Deepranjan Sarkar, Sonam Singh, Ardith Sankar, and Amitava Rakshit
Institute of Agricultural Sciences, Banaras Hindu University,
Varanasi-221005, Uttar Pradesh, India
E-mail: deep.gogreen@gmail.com
