通过灌溉提高土壤含水量（SWC）是一种潜在、有效的缓解高温胁迫的调控措施。在提高土壤含水量缓解高温影响的过程中，田间条件下基于叶绿素荧光的光合特性响应受到了有限的关注。本研究在华北平原开展了2年田间试验（2019-2020年），以郑单958（ZD958）和先玉335（XY335）为材料，在灌浆期设置三个试验处理（正常生长条件（CK）、大田升温（H）和大田升温+水分调控（HW）），研究田间高温对玉米冠层光合的影响及水分调控效应。与H处理相比，HW处理下冠层温度降低1-3℃，净光合速率（P_n）提高20%。此外，HW处理显著提高了两个品种的实际光合速率（Phi2）、线性电子流（LEF）、可变荧光（F_v）和最大光能转换效率（F_v/F_m）。同时，发现两个品种对叶绿素荧光的响应存在差异。HW处理显著提高了ZD958的类囊体质子电导率（gH⁺）和最大荧光（F_m），提高了XY335的叶绿体ATP合酶质子电导率（vH⁺）和最小荧光（F₀）。结构方程分析进一步表明，土壤水分含量与P_n、LEF和F_v/F_m呈显著正相关。提高土壤水分含量可通过延缓叶片衰老，延长光合作用有效时间，改善Phi2、LEF、F_v和F_v/F_m，提高叶片光合能力。综合本研究结果表明，提高SWC以增强灌浆期叶片光合作用，是玉米生产中适应气候变暖的一项重要技术措施。

Poor soil structure and nutrients, excessive exchangeable Na⁺, high pH as well as low enzyme activities are common in the solonetz, and significantly restrict corn (Zea mays L.) production. Cattle manure application combined with deep tillage is an important management practice that can affect soil physico-chemical properties and enzyme activities as well as corn yield in the solonetz. Field experiments were carried out in a randomized complete block design comprising four treatments: Corn with conventional tillage was used as a control, and corn with manure application combined with deep tillage as well as film mulching and aluminium sulfate were used as the experimental treatments, respectively. The relationship between corn yield and measured soil properties was determined using stepwise regression analysis. Manure application combined with deep tillage management was more effective than conventional tillage for increasing corn yield and for improving soil properties in the solonetz. The highest corn yield was obtained in the treatments with manure application+deep tillage+plastic film mulching (11 472 and 12 228 kg ha^–1), and increased by 38 and 43% comparing with the control treatment (8 343 and 8 552 kg ha^–1) both in the 2013 and 2014 experiments, respectively. Using factor analysis, three factors were obtained, which represented soil fertility status, soil saline-alkaline properties and soil structural properties both in the 2013 and 2014 experiments, respectively. Manure and deep tillage management resulted in two distinct groups of soil properties: (1) soils with manure application combined with deep tillage and (2) soils with conventional tillage. Stepwise regression analysis showed that corn yield was significantly and positively correlated to urease and available P, as well as negatively correlated to pH, electrical conductivity (EC), exchange sodium percentage (ESP), and bulk density (ρ_b). We concluded that ρb was dominant factor for corn yield on the basis of discriminant coefficient. Manure application combined with deep tillage management resulted in an increase in corn yield mainly owing to improved soil structural properties, followed by decreased soil saline-alkaline obstacle as well as increased urease activity and available P. This result is likely that the improvement in soil organic matter (SOM) from manure application greatly and positively contributed to better soil physico-chemical properties and enzyme activities, especially decrease in ρ_b. Suggestion for corn production should be improvement in soil structural properties firstly. This could cause decrease in ρ_b that key factor which limited the corn production in the solonetz.

Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon (SOC) is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon (LOC) concentration, SOC pool and carbon management index (CMI) as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates (0 (N0), 60 (N1), 120 (N2) and 180 kg ha-1 (N3)), three P-fertilization rates (0 (P0), 70 (P1) and 105 kg ha-1 (P2)) and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production (above-ground biomass and roots), bulk density (ρb), available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased ρb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass (aboveground biomass and roots) and SOC as well as LOC in 2010 and 2011 across all soil depth, respectively. The treatment with N at 180 kg ha-1 and P at 105 kg ha-1 was superior to the other treatments. The results from the 2-yr continuous experiments indicated that, in short-term, there were a few accumulation of SOC and LOC concentrations by means of N and P application to S. salsa, whereas in the long run, S. salsa with N and P application was recommended for coastal tidal lands because of its great potential of carbon sequestration, improvements of soil nutrition status and promotion of soil quality.