The present study was carried out in 2016–2017 to assess the effect of subsoiling depth on the soil bulk density, stability of soil structure, soil physical properties and summer maize yield based on a field experiment started in 2015. Four tillage depths were studied: conventional tillage 25 cm (CT₂₅); subsoiling tillage 30 cm (ST₃₀); subsoiling tillage 35 cm (ST₃₅) and subsoiling tillage 40 cm (ST₄₀). The results showed that at the 20–50 cm depth ST₃₀, ST₃₅and ST₄₀ decreased the mean soil bulk by 4.59, 7.13 and 8.27%, respectively, and at the 0–40 cm depth reduced soil compactness by 17.62, 23.63 and 36.42%, respectively, as compared to CT₂₅. ST₄₀ reduced soil compactness in the 0–40 cm soil layer under conditions of relative drought (during the maize season growing season of 2016), ST₃₅ and ST₄₀ increased macroaggregates (> 0.25 mm), improved the stability of the aggregate structure (geometric mean diameter and mean weight diameter) (20–40 cm), increased soil water storage capacity at 40–60 cm and increased maize yield by 7.89% and 8.91%, respectively. Considering the improvement of soil properties and crop yield, ST₃₅ was the optimum method to increase maize yield and modulate soil physical properties in the North China Plain.

All over the world, a common problem in the soil is the low content of available zinc (Zn), which is unevenly distributed and difficult to move. However, information on the foraging strategies of roots in response to heterogeneous Zn supply is still very limited. Few studies have analyzed the adaptability of maize inbred lines with different Zn efficiencies to different low Zn stress time lengths in maize. This study analyzed the effects of different time lengths of low Zn stress on various related traits in different inbred lines. In addition, morphological plasticity of roots and the response of Zn-related important gene iron-regulated transporter-like proteins (ZIPs) were studied via simulating the heterogeneity of Zn nutrition in the soil. In this report, when Zn deficiency stress duration was extended (from 14 to 21 days), under Zn-deficient supply (0.5 μM), Zn efficiency (ZE) based on shoot dry weight of Wu312 displayed no significant difference, and ZE for Ye478 was increased by 92.9%. Under longer-term Zn deficiency, shoot, and root dry weights of Ye478 were 6.5 and 2.1-fold higher than those of Wu312, respectively. Uneven Zn supply strongly inhibited the development of some root traits in the -Zn region. Difference in shoot dry weights between Wu312 and Ye478 was larger in T1 (1.97 times) than in T2 (1.53 times). Under heterogeneous condition of Zn supply, both the –Zn region and the +Zn region upregulated the expressions of ZmZIP3, ZmZIP4, ZmZIP5, ZmZIP7, and ZmZIP8 in the roots of two inbred lines. These results indicate that extended time length of low-Zn stress will enlarge the difference of multiple physiological traits, especially biomass, between Zn-sensitive and Zn-tolerant inbred lines. There were significant genotypic differences of root morphology in response to heterogeneous Zn supply. Compared with split-supply with +Zn/+Zn, the difference of above-ground biomass between Zn-sensitive and Zn-tolerant inbred lines under split-supply with –Zn/+Zn was higher. Under the condition of heterogeneous Zn supply, several ZmZIP genes may play important roles in tolerance to low Zn stress, which can provide a basis for further functional characterization.

This study was conducted to investigate the effects of increasing stocking density under suitable environmental conditions on the performance and ileal microbiota of broilers. A total of 108 Arbor Acres male broilers (28 days old) were allocated to a normal stocking density (NSD, normal stocking density; 31 kg/m 2 ) and a maximum allowed stocking density group (MSD, maximum stocking density; 39 kg/m 2 ). All birds were reared at a constant temperature of 21°C. At 42 days of age, bacterial DNA was extracted from ileal content, and the V3–4 hypervariable region of 16S rRNA was amplified. Increasing stocking density had no significant effect on average daily gain, average daily feed intake, and feed conversion ratio ( P >0.05). The alpha and beta diversities of the ileal microbiomes did not differ significantly between the NSD and MSD groups; however, increasing stocking density altered the composition of ileal microbiota. The relative abundance of Lactobacillales, including Lactobacillus, Enterococcus , and Streptococcus , significantly decreased in MSD broilers, compared with NSD broilers. The present results suggest that even under suitable environmental conditions, an increase in stocking density to a level of 39 kg/m 2 may disturb the composition of ileal microbiota in broilers. Further studies are needed to determine the reasons and the potential consequences for animal health and physiology.

No abstract