Integrating by-products from bioenergy technology to improve the morpho-physiological growth and yield of soybean under acidic soil.

Soil acidity may negatively affect plant growth. By-products (bottom ash (BA), biochar (BC), and biogas slurry (BS)) from bioenergy technology may change the physio-chemical properties of acidic soils and affect the plant growth parameters. The current research work was carried out to determine the impact of different bioenergy by-products to enhance soybean growth and production by alleviating the effects of acidic soil. A total of eight treatments of different bioenergy amendments (BA, BC, and BS) and their combined applications were used as follows; T1 (control), T2 (only biogas slurry); T3 (only bottom ash); T4 (only biochar); T5 (biogas slurry + bottom ash); T6 (biogas slurry + biochar); T7 (bottom ash + biochar); T8 (biochar + bottom ash + biogas slurry). Our results depicted that, the synergistic use of amendment mainly, T8 treatment (BC + BA + BS) was found most effective, which significantly prompted the dry biomass and photosynthetic rate by 42.58% and 13.25% over the T6 treatment respectively. Furthermore, the chlorophyll pigments, photochemical activities, and root growth of soybean plants enhanced significantly under T5 and T8 treatments as compared to the control. Finally, amendments significantly increased the yield in T8 treatment by increasing the pod's number, grain number, 100-grain weight and grain yield by 119.6%, 75%, 24.9%, and 83.7% as compared to T1. Conclusively, amendments are very effective in the reclamation of acidic soil and enhance the post-harvest soil pH at T8 treatment by 41.49% in comparison to T1 treatment. The organic amendments might neutralize the soil pH and change the acidic nature of the soil, which would modify the root growth of soybean and increase the photosynthetic and photochemical activities, resulting in increased soybean growth and yield.

Effects of contrasting shade treatments on the carbon production and antioxidant activities of soybean plants.

In China, maize-soybean relay-intercropping system follow the two main planting-patterns: (i) traditional relay-intercropping; maize-soybean equal row planting, where soybean experience severe maize shading on both sides of plants, and (ii) modern relay-intercropping; narrow-wide row planting, in this new planting pattern only one side of soybean leaves suffer from maize shading. Therefore, in this study, changes in morphological traits, cytochrome content, photosynthetic characteristics, carbon status, and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated at 30 days after treatment (DAT) in shade-tolerant soybean variety Nandou-12 subjected to three different types of shading conditions; normal light (NL, all trifoliate-leaves of soybean plants were under normal light); unilateral shade (US, all right-side trifoliate-leaves of soybean plants from top to bottom were under shade while all the left-side of trifoliate-leaves from top to bottom were in normal light); bilateral shade (BS, all trifoliate-leaves of soybean plants were under complete shade). Compared with BS, US conditions decreased plant height and increased stem diameter, leaf area, and biomass at 30 DAT. Biomass distribution rates to stem, petiole and leaves, and photosynthetic characteristics were markedly improved by the US at all sampling stages, which proved to be a better growing condition than BS with respect to shade tolerance. The enhanced net photosynthesis and transpiration rates in the left-side leaves (LS) of soybean plants in US, when compared with the LS in BS, allowed them to produce higher total soluble sugar (by 70%) and total soluble protein (by 17%) at 30 DAT which reduce the adverse effects of shading at right-side leaves (RS) of the soybean plants. Similarly, soybean leaves under US accumulated higher proline content in US than the leaves of BS plants. Soybean leaves grown in shading conditions (LS and RS of BS and RS of US) developed antioxidative defence-mechanisms, including the accelerated activities of SOD, POD, APX, and CAT. Comparatively, soybean leaves in US displayed lower activity levels of the antioxidative enzymes than the leaves of BS plants, showing that soybean plants experienced less shade stress in US as compared with BS treatment. Overall, these results indicate that the association of improved photosynthetic characteristics, sugar and protein accumulation and optimum antioxidative defences could be an effective approach for growing soybean in intercropping environments.