Ameliorative effects of biofertilizers on yield, water use efficiency and quality of bean under drought stress conditions – BMC Plant Biology

Report on Sustainable Irrigation Practices and Biofertilizer Application in Bean Cultivation

Executive Summary: Aligning Agricultural Innovation with Sustainable Development Goals (SDGs)

This report details an investigation into the effects of various irrigation treatments and biofertilizer applications on the yield, quality, and water efficiency of bean cultivation. The findings present a compelling case for adopting innovative agricultural practices to address global challenges, directly contributing to several United Nations Sustainable Development Goals (SDGs). By demonstrating that deficit irrigation combined with biofertilizers can maintain or even increase crop yields while significantly reducing water consumption, this research offers a viable pathway toward achieving SDG 2 (Zero Hunger) through sustainable food production and SDG 6 (Clean Water and Sanitation) by promoting water-use efficiency. Furthermore, the study supports SDG 12 (Responsible Consumption and Production) and SDG 13 (Climate Action) by providing a model for climate-resilient agriculture that lessens the environmental footprint of food systems.

Methodology and Environmental Monitoring

Irrigation Treatments and Water Content Analysis

The study was designed to evaluate the impact of controlled water application on crop performance, a critical factor for sustainable water management under SDG 6. The methodology involved several key components:

1. Evaporation and Evapotranspiration Measurement: Evaporation was monitored using a Class-A pan, with initial readings of 4.60 L increasing to 10.8 L over the study period. The total cumulative evapotranspiration was calculated at 127.40 L, providing a baseline for irrigation requirements.
2. Irrigation Levels: Three primary irrigation levels were established as a percentage of evapotranspiration, directly testing strategies for water conservation.
   • 100% (I₁₀₀): Control group receiving full water volume (15.41 mm per plant).
   • 75% (I₇₅, PRD₇₅): Deficit irrigation group receiving 75% of the water volume (13.43 mm per plant).
   • 50% (I₅₀, PRD₅₀): Severe deficit irrigation group receiving 50% of the water volume (11.45 mm per plant).
3. Soil Moisture Monitoring: Root zone soil water content was continuously monitored. As expected, moisture levels corresponded directly with irrigation amounts (100% > 75% > 50%), confirming that the treatments effectively managed water availability to the plants. This precise monitoring is essential for developing efficient water-yield models that support SDG 12.

Analysis of Results: Contributions to Water Security and Food Production

Water Budget, Crop Water Consumption, and Yield

The analysis of the water budget and crop yield provides critical insights into achieving food security with minimal environmental impact. The application of biofertilizer (BF) emerged as a significant factor in enhancing agricultural sustainability.

• Impact on Yield (SDG 2): Crop yield was directly influenced by irrigation levels, with reduced water leading to lower yields in non-biofertilizer treatments. However, the application of biofertilizers consistently mitigated these effects.
  • The highest first-class and total yields were recorded in the BF-I₁₀₀ treatment.
  • BF-I₁₀₀ yielded 12.78% more in total yield than the control (I₁₀₀).
  • Crucially, the BF-PRD₇₅ treatment (with 25% less water) yielded 2.47% more than the fully irrigated control (I₁₀₀), demonstrating a clear path to producing more food with less water.
  • Treatments with 75% and 50% irrigation, when combined with biofertilizer, produced yields comparable to the 100% irrigation treatment without biofertilizer. This finding is paramount for achieving SDG 2 in water-scarce regions.
• Mechanism of Biofertilizers: The effectiveness of biofertilizers in mitigating drought stress is attributed to the bacteria they contain, which can slow the production of the stress hormone ethylene. This enhances plant growth functions, promoting resilience and aligning with the goals of sustainable agriculture under SDG 15 (Life on Land).

Water-Yield Relationship and Efficiency

Optimizing the relationship between water input and crop output is fundamental to sustainable agriculture. This study quantifies this relationship and highlights methods to improve efficiency, directly supporting SDG 6 and SDG 12.

1. Correlation Analysis: A very high correlation was observed between the amount of irrigation water applied and the resulting crop yield (R² = 0.83 to 1.00). This confirms that water is a primary limiting factor and that efficiency gains are critical.
2. Water Use Efficiency (WUE): This metric measures the crop yield per unit of water consumed by the plant (evapotranspiration).
   • The highest WUE for total yield (13.88 kg m⁻³) was achieved in the BF-PRD₅₀ treatment.
   • This demonstrates that plants treated with biofertilizers under significant water deficit were the most efficient at converting water into biomass, a key strategy for climate adaptation under SDG 13.
3. Irrigation Water Use Efficiency (IWUE): This metric assesses the yield per unit of irrigation water applied, reflecting the overall system’s efficiency.
   • The highest IWUE for total yield (12.78 kg m⁻³) was recorded in the BF-I₅₀ treatment.
   • The lowest IWUE (9.67 kg m⁻³) was in the fully irrigated control group (I₁₀₀).
   • These results underscore that maximizing water application does not maximize efficiency. Promoting water-saving techniques is essential for responsible resource management as outlined in SDG 12.

Impact on Crop Quality and Phenology

Phenological and Morphological Characteristics

Beyond yield, the study assessed various quality parameters, which are vital for nutritional security and market value, contributing to the broader objectives of SDG 2.

• Earliness: Biofertilizer applications promoted earlier harvests, particularly in the BF-I₁₀₀, BF-I₇₅, and BF-PRD₇₅ treatments.
• Pod Characteristics: Parameters such as pod length, seed number, and pod width were highest in treatments with full irrigation and biofertilizer (BF-I₁₀₀). However, biofertilizer applications consistently improved these metrics across all irrigation levels compared to their non-inoculated counterparts.
• Plant Growth: Leaf area, fresh weight, and dry weight were highest in the fully irrigated treatments. The enhancing effect of biofertilizers was observed here as well, indicating improved plant vigor even under stress.

Biochemical and Nutritional Properties

The nutritional quality of the beans was analyzed to understand the effects of the treatments on consumer health benefits.

• Total Soluble Solids (TSS) and Acidity (TA): The highest TSS was found in the BF-I₇₅ treatment, while the highest TA was recorded in the BF-PRD₇₅ and I₁₀₀ treatments.
• Vitamin C: Vitamin C content was highest in the fully irrigated I₁₀₀ treatment, suggesting that severe water stress can impact certain nutritional components.
• Antioxidant Properties: Total phenolic and flavonoid content, as well as antioxidant activity, varied across treatments. Notably, some deficit irrigation treatments (e.g., PRD₇₅) showed high antioxidant power, indicating that moderate stress can sometimes enhance certain beneficial compounds. The application of biofertilizers was shown to reduce oxidative damage caused by drought.

Conclusion: A Pathway to Sustainable and Resilient Agriculture

Key Findings and SDG Implications

This research provides conclusive evidence that integrating biofertilizers with deficit irrigation strategies is a highly effective approach for sustainable agriculture. The key outcomes directly support the achievement of multiple Sustainable Development Goals.

• Enhanced Food Security (SDG 2): The application of biofertilizers led to significant yield increases, with the BF-PRD₇₅ treatment producing higher yields than the fully irrigated control while using 25% less water. This demonstrates a clear method for sustainable intensification.
• Improved Water Efficiency (SDG 6 & SDG 12): Water savings of 25-50% were achieved while maintaining yields comparable to full irrigation. The highest WUE and IWUE values were consistently found in water-saving treatments supplemented with biofertilizers, promoting responsible use of a finite natural resource.
• Climate Resilience (SDG 13): By mitigating the negative impacts of water stress on crop yield and quality, these practices offer a powerful tool for adapting agricultural systems to the challenges of climate change and increasing water scarcity.
• Healthy Ecosystems (SDG 15): The use of microbial biofertilizers supports soil health and reduces reliance on synthetic inputs, contributing to the preservation of terrestrial ecosystems.

Recommendations

Based on these findings, the adoption of biofertilizers in conjunction with deficit irrigation techniques like Partial Root-Drying (PRD) is strongly recommended, particularly in agricultural regions facing water limitations. This integrated approach offers a practical, evidence-based strategy for producing more food with less water, advancing global sustainability objectives.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article on irrigation treatments and biofertilizers for bean cultivation connects to several Sustainable Development Goals (SDGs) by addressing critical issues of food security, water scarcity, and sustainable agricultural practices.

• SDG 2: Zero Hunger

  This goal is central to the article, which focuses on enhancing crop yield and quality. The research explores methods to increase the production of beans, a vital food source, particularly under water-stress conditions. By investigating how to maintain or increase yield (e.g., “BF-I₁₀₀ yielded 12.78% more than I₁₀₀“) with less water, the study directly contributes to sustainable food production systems and ensuring food security.

• SDG 6: Clean Water and Sanitation

  The article’s core theme is water management in agriculture. It extensively discusses deficit irrigation, water consumption, and efficiency. By evaluating techniques that allow for significant water savings (“water savings of 25–50% were achieved with the biofertilizer used”), the research directly addresses the sustainable management of freshwater resources, which is crucial for tackling water scarcity.

• SDG 12: Responsible Consumption and Production

  This goal is addressed through the article’s focus on resource efficiency. The study demonstrates how to produce more food with fewer natural resources, specifically water. The concepts of Water Use Efficiency (WUE) and Irrigation Water Use Efficiency (IWUE) are key metrics used to show how agricultural production can become more sustainable by minimizing resource input while maximizing output.

• SDG 13: Climate Action

  The article explicitly links its research to climate change, stating, “Under current climate change conditions, saving irrigation water is of great importance.” The study presents deficit irrigation and biofertilizer application as adaptive strategies to build resilience in agriculture against climate-related hazards like drought and water scarcity, thereby contributing to climate action.

• SDG 15: Life on Land

  The use of biofertilizers as a key intervention connects to this goal. Biofertilizers can improve soil health and reduce the need for chemical fertilizers, which can degrade land over time. By promoting microbial applications that enhance plant growth and nutrient uptake, the research supports agricultural practices that are less harmful to terrestrial ecosystems and contribute to combating land degradation.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the article’s detailed analysis of agricultural practices, several specific SDG targets can be identified:

1. Target 2.4: Sustainable food production and resilient agricultural practices

   The entire study is an example of implementing resilient agricultural practices. It tests deficit irrigation and biofertilizers to maintain high crop yields under water stress, directly aligning with the goal of ensuring sustainable food production systems that can adapt to climate change and drought.

2. Target 6.4: Substantially increase water-use efficiency across all sectors

   The article is fundamentally about increasing water-use efficiency in agriculture. It meticulously measures and compares Water Use Efficiency (WUE) and Irrigation Water Use Efficiency (IWUE) across different treatments. The conclusion that “The highest WUE… and IWUE… values for first-class and total yield were found in water-saving treatments” directly supports this target.

3. Target 12.2: Achieve the sustainable management and efficient use of natural resources

   The research demonstrates a method for the efficient use of water, a critical natural resource. By showing that “treatments that saved 25% and 50% of water were able to achieve yields comparable to optimized irrigation,” the article provides a clear pathway to more sustainable resource management in agriculture.

4. Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards

   The study’s focus on maintaining crop productivity during water deficit conditions is a direct contribution to strengthening the resilience of agricultural systems. The methods tested are practical adaptations to the increasing threat of drought, a major climate-related hazard.

5. Target 15.3: Combat desertification, restore degraded land and soil

   The promotion of biofertilizers contributes to this target. The article notes that biofertilizers work by enhancing “atmospheric nitrogen fixation, and inorganic phosphate solubilization,” which improves soil fertility and health. This reduces reliance on chemical inputs that can lead to soil degradation and supports more sustainable land management practices, especially in drought-prone areas.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article is rich with quantitative data and specific metrics that can serve as direct indicators for measuring progress towards the identified SDG targets.

• Indicators for Agricultural Productivity and Resilience (Targets 2.4, 13.1)

  • Crop Yield: Measured as first-class, second-class, and total yield in tonnes per hectare (t ha⁻¹). This is a direct measure of agricultural productivity.
  • Yield Response Factor (ky): The article calculates this factor to quantify “the effect of water deficiency on plant yield,” serving as a precise indicator of a crop’s resilience to drought.
  • Crop Quality Parameters: Measurements such as pod length, seed number, total soluble solids (TSS), and vitamin C content serve as indicators of food quality, another aspect of sustainable production.

• Indicators for Water-Use Efficiency (Targets 6.4, 12.2)

  • Water Use Efficiency (WUE): Explicitly calculated and presented in kg m⁻³. This indicator measures the amount of crop yield produced per unit of water consumed by the plant (evapotranspiration).
  • Irrigation Water Use Efficiency (IWUE): Also calculated in kg m⁻³, this indicator measures the crop yield per unit of irrigation water applied, directly reflecting the efficiency of the irrigation system.
  • Amount of Irrigation Water Applied: The study quantifies water use in millimeters (mm) for different treatments (100%, 75%, 50%), providing a clear measure of water savings.

• Indicators for Sustainable Practices (Target 15.3)

  • Application of Biofertilizers: The use of microbial fertilizers (BF) is itself an indicator of a shift towards more sustainable agricultural practices that can enhance soil health and reduce chemical dependency.
  • Plant Growth Metrics: Indicators like leaf area, total chlorophyll content, and fresh/dry weight are used to show the positive effects of biofertilizers on plant health, implying improved soil and nutrient conditions.

4. Summary Table of SDGs, Targets, and Indicators

Source: bmcplantbiol.biomedcentral.com