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The objective of the study was to evaluate role of zeolite and Enterobacter sp. MN17 on Cd uptake, growth, physiological and biochemical responses of Brassica napus on Cd-contaminated soil. A sandy clay loam soil in plastic pots was spiked with Cd (0 and 80 mg kg-1) and amended with zeolite (0 and 10 g kg-1). Seeds of B. napus were inoculated with Enterobacter sp. MN17. Both inoculated and non-inoculated seeds of B. napus were sown and plants were harvested after 60 days of growth and data were collected. Although sole application of zeolite and seed inoculation reverted adverse effects of Cd in B. napus plants, the combined use resulted in even higher growth and physiological responses compared to control plants. The combined use under Cd stress increased plant height, root length, dry biomass of shoot and root up to 32%, 57%, 42% and 64%, respectively compared to control. The different physiological attributes (photosynthetic rate, chlorophyll content, transpiration rate, stomatal conductance) of B. napus were improved from 6% to 137%. Moreover, combined use of zeolite and seed inoculation on Cd-contaminated soil reduced the stress to plants as antioxidant activities decreased up to 25–64%, however enzyme activities were still higher than plants grown on normal soil. Root and shoot analysis of B. napus for Cd content depicted that zeolite and bacterium decreased Cd uptake from soil. It is concluded that combined use of zeolite and strain MN17 reduces Cd uptake from soil and improves physiological and biochemical responses of B. napus which is helpful to alleviate Cd toxicity to plants.

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There is no alternative to phosphorus (P) in agriculture as it is second most important plant nutrient after nitrogen. Mineral P fertilizers are derived from rock phosphate (RP) which is finite, non-renewable and geographically restricted to a few countries, thus its shortage likely affects agriculture in near future as the world population is growing at a greater pace. This could increase P inputs in agriculture in order to meet rising food demands which may result in the depletion of RP reserves. Furthermore, P losses from farmlands in case of mineral P fertilizers also demands the sustainable use of P not only because of its finite resources but also the environmental concerns associated with P fertilization such as eutrophication. The present study was designed to formulate biochar-based P fertilizer that would help in the sustainable use of P fertilizer. Biochar(s) were prepared using wheat straw at 350–400 °C pyrolytic temperature followed by enrichment with Di-ammonium phosphate (DAP) taking into account all possible combination of DAP to biochar on the w/w basis (0:100, 25:75, 50:50, 75:25 and 100:0). Enrichment was carried out using two different methods i.e., phosphorus enriched biochar (PEB1) by hot method and cold method (PEB2). An incubation experiment was performed to assess the impact of each biochar on selected properties of soil. The treatments were organized in factorial arrangement under complete randomized design (CRD) with three replications. Both the amendments were applied at rate of 1% of dry soil on a w/w basis. A significant increase in soil extractable P and total nitrogen (N) was recorded for the ratio 50:50 as compared to control as well of rest of treatments. Similarly, high organic contents were found for both PEB1 and PEB2 at the ratio 50:50. An incubation experiment was followed by pot trial using 50:50 for both PEB1 and PEB2 and split doses of recommended P were applied (0%, 25%, 50% and 100%) with a control under CRD with three replications using chickpea as test crop. Both PEB1 and PEB2 with 50% P have significantly improved crop growth, yield, nodulation, and plant physiological and chemical parameters as compared to a recommended dose of P alone. The result may imply that the integration of P-enriched biochar and chemical fertilizer could be an effective approach to improve chickpea production and soil properties.