Role of Microbes in Organic Farming for Sustainable Agro-Ecosystem

Interactive effects of intercropping and mulching under conservation tillage as sustainable agriculture increased cotton productivity

Climate change poses a significant risk to food security. Recent floods in Pakistan could serve as an example. In the current climate change scenario, there is a dire need to develop methods that increase crop productivity and reduce the threat of food insecurity in areas with low crop production. A detailed field experiment was conducted to check the effects of intercropping and straw mulching under conventional tillage (CT) and no tillage (NT) systems on soil health indicators and cotton productivity at the experimental area of Khwaja Fareed University of Engineering and Information Technology (KFUEIT), Rahim Yar Khan, Pakistan. The main plot treatments comprised CT and NT. The subplot treatments were sole cotton (C1), cotton + mung-bean intercropping (C2), cotton + mung-bean + straw mulching (C3) and cotton + straw mulching (C4) under CT, while sole cotton (N1), cotton + mung-bean intercropping (N2), cotton + mung-bean + straw mulching (N3) and cotton + straw mulching (N4) were the NT subplot treatments. Overall, NT increased plant height by 18.4 %, chlorophyll a and b contents by 28.2 and 21.1%, respectively, mean boll weight by 17.9%, and seed yield by 20.9% compared to CT (P < 0.05). The interaction of tillage and mulching increased plant height by 7.0% under CT and 21.8% under NT in comparison with no mulching. Similarly, straw mulching under NT increased chlorophyll a and b contents by 41.9 and 28.5%, respectively, mean boll weight by 26.9%, and cotton seed yield by 23.0% in comparison with no mulching under NT. Intercropping decreased crop yield without straw mulching but increased it under straw mulching. Further, straw mulching increased soil physicochemical properties under NT, which contributed to increasing crop productivity. We concluded that straw mulching under NT might be a promising practice for enhancing cotton yield, productivity, and soil health in low-productivity areas.

Insights on Engineered Microbes in Sustainable Agriculture: Biotechnological Developments and Future Prospects

Background

Enhanced agricultural production is essential for increasing demand of the growing world population. At the same time, to combat the adverse effects caused by conventional agriculture practices to the environment along with the impact on human health and food security, a sustainable and healthy agricultural production needs to be practiced using beneficial microorganisms for enhanced yield. It is quite challenging because these microorganisms have rich biosynthetic repositories to produce biomolecules of interest; however, the intensive research in allied sectors and emerging genetic tools for improved microbial consortia are accepting new approaches that are helpful to farmers and agriculturists to meet the ever-increasing demand of sustainable food production. An important advancement is improved strain development via genetically engineered microbial systems (GEMS) as well as genetically modified microorganisms (GMOs) possessing known and upgraded functional characteristics to promote sustainable agriculture and food security. With the development of novel technologies such as DNA automated synthesis, sequencing and influential computational tools, molecular biology has entered the systems biology and synthetic biology era. More recently, CRISPR/Cas has been engineered to be an important tool in genetic engineering for various applications in the agri sector. The research in sustainable agriculture is progressing tremendously through GMOs/GEMS for their potential use in biofertilizers and as biopesticides.

Conclusion

In this review, we discuss the beneficial effects of engineered microorganisms through integrated sustainable agriculture production practices to improve the soil microbial health in order to increase crop productivity.

Molecular Diversity Analysis of Plant Growth Promoting Rhizobium Isolated from Groundnut and Evaluation of Their Field Efficacy

Rhizobium are nitrogen-fixing bacteria which possess the nif gene that codes for the nitrogenase enzyme involved in the reduction of atmospheric dinitrogen (N₂) to ammonia. Thirty rhizobial strains were identified from ten groundnut plant root nodules collected from semi-arid regions of Rajasthan, India. The isolates were initially identified on the basis of morphological, biochemical, and molecular characteristics. These rhizobium strains were further screened for plant growth promoting activities. Twenty-eight strains were able to produce indole acetic acid, nine strains could solubilize phosphate, and twenty-nine strains exhibited positive results for siderophore and ammonia production. All the bacterial strains were able to efficiently nodulate the groundnut under pot conditions and based on multiple PGP activities six strains were selected for field evaluation. Field experiments confirmed the effectiveness of these selected rhizobium strains resulted in significantly higher nodule number, nodule dry weight, grain yield, and yield components of inoculated plants. Inoculation of the rhizobium strain GN223 followed by GN221 resulted in high yield and field efficiency. Isolation of effective microbial strains is the prerequisite to increase the yield which is evident from the field data of the present study. Hence, these strains might serve as proficient inoculants.

Development of low-cost formulations of plant growth-promoting bacteria to be used as inoculants in beneficial agricultural technologies

Phosphorus is one of the main macronutrients for plant development. Despite its large deposits in soils, it is scarcely available for plants. Phosphate-solubilizing bacteria, belonging to the group of plant growth-promoting rhizobacteria (PGPR), are capable of mobilizing deposits of insoluble phosphates in the soil. The use of PGPR as inoculants provides an environmentally sustainable approach to increase crop production. The effectiveness of inoculants depends on their proper production, formulation and storage in order to ensure the application of the required number of viable microbial cells. In order to develop inexpensive technology, low-cost compounds for biomass production and protection should be used. After the biomass production process, the product should be formulated in a liquid or a solid form, taking into account required storage time, use of protectors/carriers, storage conditions (temperature, humidity, etc.), ease of application and maintenance of beneficial effects on crops. Careful determination of these optimal conditions would ensure a low-cost efficient inoculant that would promote the growth and yield of various crops.