Deep tillage reduces the dependence of tobacco (Nicotiana tabacum L.) on arbuscular mycorrhizal fungi and promotes the growth of tobacco in dryland farming.

The traditional shallow tillage method reduces soil quality and affects the efficiency of agricultural production. Using conventional rotary tillage (12 cm) as the control, Yunyan 87 as the test variety, and paddy soil as the test site, we studied the effects of deep tillage (subsoiling 30 cm) on soil nutrients, arbuscular mycorrhizal fungi (AMF), and tobacco (Nicotiana tabacum L.) growth. The results showed that deep tillage increased the content of organic carbon, available phosphorus (AP), and available potassium (AK) in the 20-40 cm soil layer. The AMF community was also affected by deep tillage. Glomus, the dominant genus in both groups, increased significantly in soil after deep tillage. The AMF colonization rate was lower than that of conventional rotary tillage. Deep tillage was beneficial for tobacco growth in the middle and late stages. The root growth and nutrient content of the tobacco plants increased. Deep tillage significantly improved the output value of tobacco plants. Deep tillage is conducive to improving soil fertility, promoting the vigorous growth of roots, reducing the dependence of tobacco on AMF, and promoting the high quality and yield of tobacco in the drylands of Hunan.

pH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances.

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2-8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.