Response of black wheat to combined organic and bio-fertilizers under field conditions

The experimental design based on Randomized Block Design (RBD) with ten fertilizer treatments, with three replications (30 ploughed plots with average size of 2.5 × 4 (10 m²)) was used to carry out this study (Fig. 2). The line sowing of wheat was carried out 30 kg ac⁻¹ at a distance (R-R) of 35 cm. The wheat seeds were soaked overnight in bio-pesticide (Trichoderma + Pseudomonas) 5 ml/liter of water before sowing to avoid infection with soil-borne pathogens. The fertilizer treatments were applied every 30 days after sowing. No pesticides were used throughout the experiment. Different combinations of organic and bio-fertilizers were used in this study. While Jaivik Khad (organic fertilizer) was used before sowing at the rate of 100 kg/acre as base fertilizers with all treatments, the Patanjali PSB plus, Patanjali Bio-NPK plus, Patanjali Bio Potash Plus (2 ml l⁻¹, 3 ml l⁻¹ and 4 ml l⁻¹ each) were used as bio-fertilizers immediately after sowing and thereafter every 30 days interval. The final prepared solution of each bio-fertilizer was used with a rate of 2 l per plot (Table 1). The analysis of the soil was also done before the start of the field trial (Table 2).

Figure 2.

Field trial on black wheat crop in the field on 60 days after sowing (DAS). (A-B) wheat in primary stage in the experimental field, (C) wheat spikes, (D) kernels of black wheat.

To analyze the impact of various treatments on crop growth, a series of parameters were employed. Three healthy and disease-free plants were randomly selected for each treatment and their replicates (total nine per treatment) with the use of the L sampling technique (excluding border plants) at 60 and 90 days (at 30-day interval) after sowing. The growth parameters including plant height (shoot and root) (cm), shoot and root biomass (g), moisture content (shoot and root), leaf area (counted as length × width, cm²), accumulation of dry matter (g), and the total chlorophyll content were measured at the distinct periods of 60 and 90 days after the sowing. The plant length was expressed as the total length of the shoot and root, while, biomass and moisture content were measured based on fresh and dry weight measurements. The total chlorophyll content was determined using a SPAD meter and the results were expressed as SPAD meter values. The Crop Growth Rate (CGR) in g day⁻¹, Relative Growth Rate (RGR) in g day⁻¹ and Net assimilation rate (NAR) in g m⁻² day⁻¹ were calculated by using the following formulas: Crop Growth Rate CGR=W2−W1/t2−t1 {\rm{Crop}\;\rm{Growth}\;\rm{Rate}}\;\left( {{\bf{CGR}}} \right) = \left( {{{\rm{W}}_2} - {{\rm{W}}_1}} \right)/\left( {{{\rm{t}}_2} - {{\rm{t}}_1}} \right)

• W₁ = initial fresh weight (at time t₁)

• W₂ = final fresh weight (at time t₂)

• t₂ – t₁ = time interval

Relative Growth Rate RGR=lnW2−lnW1/t2−t1 {\rm{Relative}\;\rm{Growth}\;\rm{Rate}}\;\left( {{\bf{RGR}}} \right) = \left( {\ln \left( {{{\rm{W}}_2}} \right) - \ln \left( {{{\rm{W}}_1}} \right)} \right)/\left( {{{\rm{t}}_2} - {{\rm{t}}_1}} \right)

• ln = natural logarithm

• W₁ = dry weight at time t₁

• W₂ = dry weight at time t₂

• t₂ – t₁ = time interval

Net Assimilation Rate NARNAR=W2−W1/t2−t1×lnA2−lnA1/A2−A1 \matrix{{{\rm{Net}}\;{\rm{Assimilation}}\;{\rm{Rate}}\;\left( {{\bf{NAR}}} \right)} \cr {{\rm{NAR}} = \left( {{{\rm{W}}_2} - {{\rm{W}}_1}} \right)/\left( {{{\rm{t}}_2} - {{\rm{t}}_1}} \right) \times \ln \;{{\rm{A}}_2} - \ln \;{{\rm{A}}_1}/{{\rm{A}}_2} - {{\rm{A}}_1}} \cr }

• W₁ and W₂ = total dry weight of plant at time t₁ and t₂ respectively

• A₁ and A₂ = total leaf area at time t₁ and t₂ respectively

• t₂ − t₁ = time interval in days

• ln = natural logarithm

The specific parameters at crop maturity (specifically between 120–135 days of sowing), which include the length of spikes (cm), 100 g seed weight, number of seeds per spike, yield per plot (kg) and total yield per acre (q), were assessed. The grain components like: moisture content, total ash, protein content, gluten content, nitrogen (N), phosphorus (P), copper (Cu), iron (Fe), zinc (Zn), manganese (Mn) and potassium (K) of wheat grains were also assessed during this study. All nutraceutical investigations of seed grains were carried out at the Central Laboratory located at Patanjali Food & Herbal Park Pvt. Ltd., an accredited testing facility endorsed by the National Accreditation Board for Testing and Calibration Laboratories (NABL).

All the data collected were classified and processed in Microsoft Excel and then transferred to R version 4.3.1 (R Core Team, 2022) for further analysis. The normality of distribution and homogeneity of variance were tested before performing the analysis of variance (ANOVA). Multiple comparisons were made using the “agricolae” package (de Felipe, Yaseen, 2020). Pearson correlation was used to assess relationship between fertilizer dosage and wheat yield. Spearman correlation was used to highlight the relationships between variables using the “metan package” (Olivoto, Lúcio, 2020).

The soil of the experimental site was found alkaline with a pH of 7.83 ±0.06, electrical conductivity (0.19 ±0.03 dS m⁻¹), organic carbon (0.23 ±0.00 %w), organic matter (0.70 ±0.01%w), available nitrogen (145.93 ±4.75 kg ha⁻¹), available phosphorous (14.84 ±6.21 kg ha⁻¹), exchangeable potassium (55.18 ±8.46 kg ha⁻¹), zinc (0.81±0.13 ppm), sulfur (4.51 ±0.98 ppm), iron (9.17 ±5.92 ppm), manganese (1.13 ±0.11 ppm), copper (0.69 ±0.12 ppm) (Table 2).

A considerable effect on all fertilizer treatments was observed on all growth parameters of the black wheat crop. However, these effects vary on different growth parameters (Table 3). At the level of doses of applied fertilizers, the PSB plus (3 ml l⁻¹), Patanjali Bio-NPK plus (2 ml l⁻¹), or Patanjali Bio Potash Plus (2 ml l⁻¹) were considered effective, although the efficacy of doses quantities showed variation in growth and yield parameters. In terms of growth parameters, positive effects were exhibited upon applying organic and bio-fertilizers. The results of the present study revealed that the wheat grown under (T2 i.e. NPK (2 ml l⁻¹) has enhancing effects on plant length (shoot + root); whereas, the crop under T3 was higher in shoot and root biomass and number of tillers; high chlorophyll content in T2, T4, T5, T6 and T8 showed enhanced efficacy in leaf area. The synergistic effects of each fertilizer may be responsible for the effectiveness of the combination treatment of bio-fertilizers and Jaivik Khad. The application of Jaivik Khad as an organic fertilizer perhaps proved helpful in supplying macro and micronutrients and enhancing the soil’s ability to hold onto water and nutrients. The application of Jaivik Khad as an organic fertilizer not only enhances the organic matter of the soil but also encourages the growth of beneficial microbes that can break down inorganic phosphate and produce phytohormones, which are known to stimulate plant growth (Bedine et al., 2022; Kouam et al., 2023). Bio-fertilizers consist of beneficial microbes that can fix the nutrients present in the soil and make them available to the crop plants and enhancing the vegetative growth and yield parameters of black wheat crops. Ahmed et al. (2011) studied wheat productivity in newly reclaimed sandy soil in Egypt. They studied the efficacy of applying organic and bio-fertilizers singly or in combination on the growth and yield of black wheat. The study showed that mixed inoculate generally had a greater positive impact than a single inoculum. Similarly, a field experiment was carried out at the agriculture farms of Mansoura University to study the effects of different bio- and organic fertilizers and their combination on hybrid maize growth, yield, and grain quality. Like the present study, similar observations were made in that study. The results recommended combining the organic and bio-fertilizer mixture to enhance growth, yield, and nutrient uptake in maize (Gao et al., 2020).

Like growth, the application of organic- and bio-fertilizers also exhibited considerable effects on the yield of black wheat crops. The enhanced spike length (9.433 ±0.481 cm) and weight of 100 seeds (4.880 ±0.445) collected from spikes were observed under treatment T6 (Jaivik Khad RFD + Patanjali Bio Potash Plus 3 ml l⁻¹), while the maximum number of grains per spike (57.000 ±7.550) were observed in spikes produced by black wheat plants growing under treatment T9 (Jaivik Khad RFD + Patanjali Bio Potash Plus 4 ml l⁻¹). However, the highest total yield per acre (15,85 q) was observed in the black wheat crop growing under treatment T9 (Jaivik Khad RFD + Patanjali Bio Potash Plus 4 ml l⁻¹). Thus, the treatment T9 (Jaivik Khad RFD + Patanjali Bio Potash Plus 4 ml l⁻¹) exerted a good impact on the yield parameters of the wheat crop (Table 4). Two other treatment combinations – T2 (Jaivik Khad and Patanjali Bio-NPK Plus2 ml l⁻¹) and T7 (Jaivik Khad and PSB Plus 4 ml l⁻¹) also exhibited good yield, 15.69 and 15.42 q per acre, respectively (Fig. 3). The analysis of the seed grains of black wheat revealed the presence of a wide range of major and minor constituents which reflects that these seed grains are a rich source of different nutrients, including protein (13.77%), nitrogen (2.20%), phosphorus (5111.59 mg kg⁻¹), copper (4.81 mg kg⁻¹), iron (47.76 mg kg⁻¹), zinc (20.19 mg kg⁻¹), manganese (53.61 mg kg⁻¹) and potassium (4481.12 mg kg⁻¹). An earlier study based on the application of organic manures and bio-fertilizers on growth and yield parameters of cowpea (Vigna unguiculata) revealed a positive response on growth and yield attributes. In comparison to the control, a 46% increase in the yield of cowpea was observed during the study (Yadav et al., 2019). Similar work was also carried out by Singh et al. (2019 a, b) to evaluate the effects of different organic, inorganic and bio-fertilizers on the yield and yield components of wheat. The study concluded that fertilizer treatment combinations like farmyard manure, poultry manure, and Azotobacter in different combinations have significant effects on the yield of wheat along with enhancing growth parameters. In a similar study, the combined application of biofertilizers with organic manures enhanced soil fertility and the bioavailability of major nutrients in the soil and untimely plant growth of the fruits at a desired level. Moreover, bio-fertilizers are now being considered eco-friendly and low-cost agriculture inputs that have wonderful potential to increase the yield of wheat and other food and vegetable crops (Kumar, Urmila, 2018; Karanveer et al., 2024). A recent study by Balkrishna et al. (2024a) also advocated the use of organic fertilizers to enhance the performance of wheat and other crops. Many other studies on millets (Pallavi et al., 2017; Susmitha et al., 2022), vegetable crops (Rajput et al., 2022; Kapoor et al., 2023; Balkrishna et al., 2024b) and other crops (Gao et al., 2020) also justified the use of organic and bio-fertilizers to propose a sustainable and ecological method to enhance agricultural productivity.

Figure 3.

Total yield of black wheat under different treatment conditions.

The Crop Growth Rate (CGR), Relative Growth Rate (RGR) and Net Assimilation Rate (NAR) for wheat plants revealed distinct differences in the growth performance of wheat plants subjected to various fertilizer treatments (Fig. 4). In comparing the treatments, the control (T0), which received no fertilizers, showed the lowest values for CGR (0.5604 g day⁻¹), RGR (0.0708 g day⁻¹), and NAR (0.0154 g m⁻² day⁻¹), confirming the necessity of nutrient supplementation for optimal wheat growth. Among all treatments, T3 (POTASH 2 ml l⁻¹) demonstrated the most significant improvement in all three growth parameters, achieving the highest CGR (0.918 g day⁻¹), RGR (0.0838 g day⁻¹), and NAR (0.0255 g m⁻² day⁻¹). This indicates that T3 not only supported an overall increase in biomass but also enhanced the efficiency of biomass accumulation relative to leaf area and initial plant mass. The superior performance of T3 may be attributed to the role of potassium in promoting enzyme activation, osmoregulation, and efficient photosynthate translocation, all of which are vital during early vegetative growth. The benefit here could be due to the presence of phosphate-solubilizing bacteria (PSB) enhancing phosphorus availability, which is crucial for energy transfer and root development. Similarly, T4 (PSB 3 ml l⁻¹) and T1 (NPK 2 ml l⁻¹) also showed moderate increases in growth parameters, indicating a dose-dependent but limited improvement compared to T2 and T3. Treatments T5, T6, T7, T8, and T9, representing higher doses of NPK, POTASH, and PSB (at 3 and 4 ml l⁻¹), showed marginal or reduced benefits compared to their lower-dose counterparts. For instance, T9 (POTASH 4 ml l⁻¹) recorded a relatively lower CGR (0.7215 g day⁻¹) and NAR (0.0203 g m⁻² day⁻¹) despite a decent RGR (0.081 g day⁻¹), suggesting that increasing fertilizer concentration beyond an optimal point may not further enhance assimilation or biomass gain, and could potentially hinder plant metabolic processes (Fig. 4).

Figure 4.

Crop Growth Rate, Relative Growth Rate and Net Assimilation Rate for black wheat plants subjected to various fertilizer treatments.

Correlation among the parameters showed that treatments with higher CGR and RGR generally corresponded with higher NAR, indicating a positive interaction between biomass production, relative growth, and photosynthetic efficiency. Overall, POTASH 2 ml l⁻¹ (T3) emerged as the most effective treatment, possibly due to its optimal support of both vegetative biomass accumulation and photosynthetic efficiency. This underscores the importance of potassium and appropriate fertilizer dosing in enhancing wheat growth during the initial stages.

The Pearson correlation coefficient analysis between fertilizer dosage and black wheat yield demonstrated clear differences among the nutrient treatments. Phosphate-Solubilizing Bacteria (PSB) showed a very strong positive correlation (r ≈ 0.997), reflecting a consistent dose-dependent increase in yield. The grain yield increased from 2759.000 g at 2 ml l⁻¹ to 2922.333 g at 3 ml l⁻¹, and further to 3048.667 g at 4 ml l⁻¹, indicating that higher PSB concentrations substantially improved productivity. This trend highlights the effectiveness of PSB in enhancing nutrient availability and supporting yield improvement in black wheat. In contrast, NPK bio-fertilizer exhibited a strong negative correlation (r ≈ −0.834), suggesting that higher dosages were not beneficial. Yield was highest at the lowest concentration (3102.333 g at 2 ml l⁻¹), but declined at higher levels (2975.000 g at 3 ml l⁻¹ and 2983.667 g at 4 ml l⁻¹). This finding implies that excessive NPK bio-fertilizer application may lead to nutrient imbalance or reduced efficiency, emphasizing the importance of optimized, rather than increased, NPK use for black wheat cultivation. Potash treatments displayed a moderately strong positive correlation (r ≈ 0.763), with yields of 2779.333 g at 2 ml l⁻¹, 2697.000 g at 3 ml l⁻¹, and a marked improvement at 3132.333 g at 4 ml l⁻¹. Although some variability was observed, the overall trend suggested that higher Potash dosages were favorable for yield enhancement, particularly at the 4 ml l⁻¹ level (Fig. 5).

Figure 5.

Pearson correlation coefficient to depict the effect between fertilizer dosage and yield.