Integrative effects of different mulching practices and Azospirillum brasilense on wheat growth, physiology, and soil health under drought stress

Azospirillum brasilense, a plant growth-promoting rhizobacterium that plays a vital role in sustainable wheat production by enhancing nutrient uptake, improving stress tolerance, and reducing reliance on chemical fertilizers. This study aimed to investigate the integrative effects of Azospirillum brasilense inoculation and different mulching practices on the growth, physiology, and soil health of wheat (Triticum aestivum L.) under drought stress, particularly during the critical booting stage. The primary research question focused on identifying whether these combined treatments could mitigate drought-induced damage and enhance plant performance. The experimental was consisted of 9 treatments, including T0 (control: no mulch, no drought, no soil microbes), T1 (drought stress at the booting stage (DB)), T2 (DB + A. brasilense), T3 (DB + wheat straw mulch), T4 (DB + rice husk mulch), T5 (DB + plastic mulch), T6 (DB + A. brasilense + wheat straw mulch), T7 (DB + A. brasilense + rice husk mulch), and T8 (DB + A. brasilense + plastic mulch) with randomized complete block design having three replications. Various growth, yield, physiological, and soil nutrient parameters were assessed. Data analysis included ANOVA, cluster heatmap, and principal component analysis (PCA) to evaluate treatment impacts. Drought stress significantly reduced plant height (34.24%), 1000-grain weight (49.05%), and photosynthetic pigments. However, treatments combining A. brasilense with organic mulches (T6: wheat straw and T7: rice husk) substantially improved plant biomass, photosynthetic rate (up to 24.67%), stomatal conductance (7.54%), and soil nutrient uptake. T6 showed the highest increase in chlorophyll a (118.74%) and grain weight (78.78%) compared to drought alone. PCA and heatmap analyses revealed strong clustering of treatments, highlighting T6 as the most effective strategy. The combination of A. brasilense and organic mulching (especially wheat straw) effectively mitigated drought stress in wheat by enhancing physiological resilience, nutrient uptake, and soil health. The demonstrated benefits suggest that incorporating bio-inoculants with locally available mulching materials can be scaled up as a practical intervention for climate-smart agriculture.