以28份小麦农家种和63份选育品种为供试验材料开展田间试验，研究小麦农家种和选育品种籽粒锌、铁含量差异及对叶面施肥的响应。研究表明，供试小麦品种的平均锌含量为41.8 mg kg^-1（29.0-63.3 mg kg^-1），平均铁含量为39.7 mg kg^-1 （27.9-67.0 mg kg^-1）。小麦农家种的锌和铁含量分别比选育品种高11.0%和4.8%，但小麦农家种的收获指数、单穗粒重、单穗粒数和千粒重均低于选育品种。相关分析表明，籽粒锌、铁含量均与收获指数、单穗粒重和单穗粒数呈显著负相关，而与千粒重相关性较低，据此可推测，农家种籽粒锌、铁含量高于选育品种可能与农家种的收获指数、单穗粒重和单穗粒数较低有关，而与千粒重无关。叶面喷施锌肥，农家种和选育品种的籽粒锌含量均显著增加，农家种的籽粒锌含量增加了12.6 mg kg^-1，约是选育品种的两倍（6.4 mg kg^-1）。叶面喷施铁肥，农家种和选育品种的籽粒铁含量分别增加了3.4 和1.2 mg kg^-1，均没有达到显著水平。可以看出，与小麦选育品种相比，农家种不仅籽粒锌、铁含量较高，且在叶面施锌条件下籽粒锌含量增幅较大，表明我国小麦农家种可作为潜在种质资源用于提高现代选育品种的微量元素含量。

We investigated the soil microbiologic characteristics, and the yield and sustainable production of winter wheat, by conducting a long-term fertilization experiment.  A single application of N, P and K (NPK) fertilizer was taken as the control (CK) and three organic fertilization treatments were used: NPK fertilizer+pig manure (T1), NPK fertilizer+straw return (T2), NPK fertilizer+pig manure+straw return (T3).  The results showed that all three organic fertilization treatments (T1, T2 and T3) significantly increased both soil total N (STN) and soil organic carbon (SOC) from 2008 onwards.  In 2016, the SOC content and soil C/N ratios for T1, T2 and T3 were significantly higher than those for CK.  The three organic fertilization treatments increased soil microbial activity.  In 2016, the activity of urease (sucrase) and the soil respiration rate (SRS) for T1, T2 and T3 were significantly higher than those under CK.  The organic fertilization treatments also increased the content of soil microbial biomass carbon (SMBC) and microbial biomass nitrogen (SMBN), the SMBC/SMBN ratio and the microbial quotient (qMB).  The yield for T1, T2 and T3 was significantly higher than that of CK, respectively.  Over the nine years of the investigation, the average yield increased by 9.9, 13.2 and 17.4% for T1, T2 and T3, respectively, compared to the initial yield for each treatment, whereas the average yield of CK over the same period was reduced by 6.5%.  T1, T2, and T3 lowered the coefficient of variation (CV) of wheat yield and increased the sustainable yield index (SYI).  Wheat grain yield was significantly positively correlated with each of the soil microbial properties (P<0.01).  These results showed that the long-term application of combined organic and chemical fertilizers can stabilize crop yield and make it more sustainable by improving the properties of the soil.

Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals (nHRS), drought tolerance and water use efficiency of winter wheat (Triticum aestivum). The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots (1.06 and 0.94 mmol g-1 s-1, respectively). The soil water content (SWC) at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants (61.1-44.6% field water capacity) than for intact root plants (57.9-46.1% field water capacity). At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield ( PS II), the maximum photochemical efficiency of PS II (Fv/Fm), coefficient of photochemical quenching (qP), and coefficient of non-photochemical quenching (NPQ), in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency (WUE) than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of droughtresistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.