The interaction mechanism between crop and soil microbial communities is a key issue in both agriculture and soil ecology. However, how soil microbial communities respond to crop planting and ultimately affect crop health still remain unclear. In this research, we explored how soil microbial communities shifted during tobacco cultivation under different rotation systems (control, maize rotation, lily rotation and turnip rotation). Our analyses showed that soil microbial communities had a general response pattern to tobacco planting, as the abundances of Proteobacteria and Planctomycetes increased while Acidobacteria and Verrucomicrobia decreased during tobacco cultivation, no matter which rotation system was adopted. Notably, tobacco decreased the diversity and co-occurrence of soil microorganisms, but maize rotation might suppress tobacco bacterial wilt by alleviating the decrease in biodiversity and co-occurrence. Molecular ecological network analysis indicated that there was stronger competition between potential disease suppressive (e.g., Acidobacteria) and inducible bacteria (e.g., Chloroflexi) in maize rotation systems. Both soil properties (e.g., pH, Ca content) and microbial communities of tobacco mature period depended on their counterparts of fallow period, and all these factors shaped tobacco disease comprehensively. Both soil microbial communities of fallow stage and tobacco selection shaped the communities of tobacco mature stage. And effective rotation crop (maize) could decrease the incidence of tobacco bacterial wilt by alleviating the decrease in diversity and co-occurrences of microbial populations. This study would deepen our understanding about succession mechanism of soil microbial communities during crop cultivation and their relationship with crop health.

It is important to ensure the nutritional quality and safe production of rice. Here, plot experiments were used to analyze the effects of three soil amendments—10 t ha⁻¹ of biochar (BC), 1.5 t ha⁻¹ of lime (LM), and 2.25 t ha⁻¹ of silicon–calcium fertilizer (SC)—on the soil characteristics, rice yield and quality of double-cropping rice grown in mildly cadmium-polluted paddy fields. Compared with the control treatment (CK), the BC and SC treatments significantly improved rice processing, appearance and nutritional quality, but reduced cooking quality. All three soil amendments significantly reduced cadmium (Cd) content in brown rice. Soil amendments could significantly increase soil pH and reduce soil available Cd content. The application of the BC and SC treatments increased the content of each nutrient index in the soil (SOM, NN, AP, AK). Correlation analysis showed that the improvement in rice processing, appearance, and nutritional quality was mainly affected by the comprehensive effects of soil SOM, NN, AP and AK; the hygiene quality was mainly affected by soil pH and available Cd. In terms of benefit analysis combined with cost, the SC treatment had the highest benefit effect. Taken together, in mildly cadmium-polluted paddy fields, the application of silicon–calcium fertilizer improved the soil quality, thereby increased the yield and quality of rice, and had the best effect on increasing income.

Cadmium (Cd) contamination in rice is a potential health hazard when ingested through the food chain worldwide. Reducing the Cd content in rice through agronomic measures is an effective way to reduce the risk of Cd contamination to human health. In order to clarify the correlation between temperature and light conditions and Cd accumulation (Cd-A) and Cd content of brown rice (CdBR) during the field growth period (FGP) of rice, consequently provide a theoretical basis for the selection of sowing date (SD) for “Low-Cd-Rice” production, field experiment with different SDs was carried out by using two rice varieties with different Cd accumulation characteristics (Luliangyou 996, V1, a high Cd accumulation variety; Zhuliangyou 819, V2, a low Cd accumulation variety). The results showed that the temperature and light factors such as mean soil temperature (ST), mean air temperature (AT), soil accumulation temperature (SAT), air accumulation temperature (AAT), ultraviolet radiation accumulation (UR), photosynthetic radiation accumulation (PR), light intensity accumulation (I) and sunshine hours accumulation (SH) varied to different degrees under different SDs; The difference in CdBR in two varieties could be up to 2.82 and 8.48 times respectively among SDs, with the CdBR of S4 and S5 of V2 being lower than the national standard of 0.2 mg/kg. The relative expression of OsIRT1 in the root system was significantly positively correlated with ST, SAT, AT, AAT, and SH, while OsNramp5, OsNramp1 , and OsHMA3 showed significant negative correlations with ST, SAT, AT, AAT, and SH in relative expression in the root system; OsIRT1 expressed in the roots of V1 was significantly negatively correlated with CdBR, while OsHMA3 expression was significantly positively correlated with CdBR; OsLCD, OsNramp1 , and OsHMA3 expression in the roots of V2 were significantly positively correlated with Cd-A and CdBR, while OsIRT1 in the roots of V2 and OsLCT1 in the leaves were significantly negatively correlated with Cd-A; The expression of OsNramp5 in roots was significantly negatively correlated with Cd-A and CdBR in both V1 and V2. Bias correlation analysis showed that ST, SAT, AT, and AAT were significantly negatively correlated with both Cd-A and CdBR; SH was significantly negatively correlated with CdBR in V1. Summarily, the temperature and light conditions during the FGP of rice and their regulation of the expression levels of related genes could be changed by sowing selection, so as to achieve safe production of rice under Cd-contaminated fields.