This study was conducted in a rice-based cropping scheme to investigate the impact of green manuring on soil health, considering soil physicochemical properties and sustainable crop production. A field experiment was started on 2 November 2015 and completed on 15 April 2018 under a rice–berseem (Trifolium alexandrinum) cropping system in calcareous soil. Two green manuring patterns, rice–berseem and rice–wheat–sesbania (rostrata), were compared with a commonly practiced rice–wheat (Oryza sativa-Triticumaestivum) cropping pattern. Green manuring of the berseem crop (last cutting) along with 50, 75, and 100% of the recommended fertilizer doses of nitrogen, phosphorus, and potassium (NPK) were compared with recommended NPK fertilization along with control (no fertilizer). The plant growth parameters of rice, including plant height, tillers per plant at maturity, and yield data, were recorded at harvest. The pre-sowing soil analysis revealed that the experimental soil was low in salts, and the nutrient (NPK) status was very low. The results indicated that green manuring substantially enhanced the grain and straw yield of rice crops. Green manuring combined with 75% of recommended NPK produced the highest grain yield (5.83 t ha⁻¹ in year III) compared to the other treatments. The soil analysis showed that the bulk density was reduced while soil porosity, organic carbon, and N, K, and P contents were significantly improved. From the results of this study, it is recommended that under calcareous soil conditions, the regular use of green manuring can significantly improve crop growth, yield, and physicochemical properties of soil and, therefore, should be adopted by farmers.

Drought is one of the major limitations to agricultural productivity, suppressing plant growth and yield of food crops throughout the world particularly in arid and semiarid regions. Drought-tolerant carbonic anhydrase (CA; EC 4.2.1.1)-containing endophytic bacteria may improve plant growth under stressed conditions. In the present study, effect of drought-tolerant CA-containing endophytic bacteria on growth and physiology of wheat under water-deficit conditions was studied. One hundred and fifty isolates were isolated from wheat plants and screened for their ability to tolerate polyethylene glycol (PEG) 6000-induced water-deficit stress (−0.31 to −3.20 MPa). Fifty isolates exhibiting intrinsic ability to tolerate stress were further screened for CA activity. Ten drought-tolerant isolates with higher CA activity were evaluated for improving wheat growth under water-deficit conditions (−0.04, −1.09, −1.23 MPa). Results showed that PEG-mediated water-deficit stress significantly reduced growth of wheat. However, inoculation with isolates WR2, WS11 and WL19 significantly enhanced seedling growth by improving maximum root length, shoot length, root and shoot dry weight under non-stressed as well as stressed conditions. These isolates were identified by 16S rRNA as Bacillus marisflavi (WR2) Bacillus thuringiensis (WS11) and Bacillus subtilis (WL19). Isolate WL19 also improved chlorophyll content, photosynthetic rate, CA activity and relative water content compared to uninoculated control plants. Overall, our findings suggest that endophytic bacterial isolates WR2, WS11 and WL19 with CA activity can enhance photosynthesis and biomass of wheat seedlings under water-deficit conditions. Abbreviations: CA: Carbonic anhydrase; PEG: Polyethylene glycol; CO₂: Carbon dioxide; HCO^3–: Bicarbonate; TSA: Tryptic Soy Agar; LB: Luria Bertani; A: CO₂ assimilation rate; E: Transpiration rate; g_s: Stomatal conductance; C_i: Substomatal CO₂ concentration; RWC: Relative water content; EL: Electrolyte leakage

Zinc (Zn) biofortification in staple cereal grains is a low-cost and viable option to overcome the Zn deficiency in humans beings in developing countries. Intensive cropping with no/low micronutrient fertilization has resulted in soil Zn deficiency around the globe. Moreover, the Zn use efficiency of soils is usually low owing to its fixation into unavailable forms. Hence, the present study was conducted to investigate the integrated effects of urea coated with bioaugmented Zn on wheat growth, yield, and Zn biofortification. The bioaugmented Zn was prepared by inoculating ZnO with Bacillus sp. AZ6. Three levels (0.5, 1.0, and 1.5%) of ZnO, bioaugmented Zn, and bioaugmented Zn+organic material were coated on urea fertilizer and applied to investigate the performance of the wheat crop. The applied treatments were compared with absolute control and sole application of ZnSO4, and Bacillus sp. AZ6. Results revealed that the application of urea coated with 1.5% bioaugmented Zn significantly increased wheat growth, yield, and Zn biofortification as compared to the sole ZnSO4, and Bacillus sp. AZ6 treatments. The application of urea coated with 1.5% bioaugmented Zn improved the accumulation of Zn in shoots and grains by 83.3% and 144.0%, respectively, compared to absolute control. The increase in grain Zn content was owing to the significant reduction in grain phytic acid (69.9%) and phytate:Zn molar ratios (87.6%) compared to absolute control. Therefore, it was concluded that the application of urea coated with bioactivated ZnO can improve Zn biofortification in wheat grain by reducing phytic acid concentrations, consequently fulfilling human Zn needs through the consumption of such Zn enrich wheat grains.