Differences of yield and nitrogen use efficiency under different applications of slow release fertilizer in spring maize

Excessive or insufficient application of fertilizer has raised broader concerns regarding soil and environmental degradation. One-time application of slow release fertilizer (SF) has been widely used to reduce yield gap with potential maize yield and improve nitrogen use efficiency (NUE). A 2-year field experiment (2018–2019) was conducted to evaluate the effects of SF rates from 0 to 405 kg N ha^–1 (named F0, SF225, SF270, SF315, SF360, and SF405) and 405 kg N ha^–1 of common fertilizer (CF405) on the grain yield, biomass and N accumulation, enzymatic activities related with carbon–nitrogen metabolism, NUE and economic analysis. Results indicated that the highest grain yields, NUEs and economic returns were achieved at SF360 in both varieties. The enzymatic activities related with carbon–nitrogen metabolism, pre- and post-silking accumulation of biomass and N increased with increasing SF rate, and they were the highest at SF360 and SF405. The grain yield at SF360 had no significant difference with that at SF405. However, the N partial factor productivity, N agronomic efficiency and N recovery efficiency at SF360 were 9.8, 6.6 and 8.9% higher than that at SF405. The results also indicated that the average grain yields, NUE and economic benefit at SF405 were 5.2, 12.3 and 18.1% higher than that at CF405. In conclusion, decreasing N rate from 405 kg ha^–1 (CF) to 360 kg ha^–1 (SF) could effectively reduce the yield gap between realized and potential maize yields. The N decreased by 11.1%, but the yield, NUE and economic benefit increased by 3.2, 22.2 and 17.5%, which created a simple, efficient and business-friendly system for spring maize production in Jiangsu Province, China.     

茭白冷藏期间蛋白质表达谱的变化

为探讨茭白冷藏期间衰老的分子机理,应用蛋白质组学技术,研究了茭白冷藏期间蛋白质表达谱的变化。结果显示,双向电泳胶上共检测到大约650个蛋白点,其中35个蛋白表达量存在2.0倍以上显著(p0.05)差异,经过串联飞行时间质谱分析,成功鉴定出29个蛋白,根据其功能可分为6类,即代谢(20.7%)、细胞结构(27.6%)、抗胁迫(20.7%)、衰老(6.9%)、蛋白质合成(13.8%)和功能未知蛋白(10.3%);其中:代谢相关蛋白3个上调表达、3个下调表达,细胞结构相关蛋白6个上调表达、2个下调表达,抗胁迫相关蛋白4个上调表达、2个下调表达,衰老相关蛋白2个上调表达,蛋白质合成相关蛋白4个及功能未知蛋白3个均下调表达。这些差异表达蛋白的功能分析表明,茭白采后衰老机理可能涉及物质代谢过程的调整、能量代谢途径的改变、活性氧清除能力的减弱以及细胞结构的解体。     

快慢羽品系贵妃鸡体尺性状及屠宰性能的比较分析

对20周龄的6只快羽贵妃鸡与6只慢羽贵妃鸡的体尺性状与屠宰性能进行比较分析.结果表明,两品系间的体尺性状与屠宰性能均为慢羽鸡大于快羽鸡,且髋宽、半净膛率两品系间差异显著(P<0.05).两品系间的内脏器官的体积大小和骨架结构大小存在一定的规律性,骨架指数与睾丸重慢羽鸡均大于快羽鸡,器官指数则是慢羽鸡小于快羽鸡.     

不同水稳性团聚体测定方法的对比研究

水稳性团聚体是研究土壤肥力、质量及侵蚀强度的重要参考指标.研究目的不同,测定其含量的方法常常也不同.采用非真空快速浸润法、非真空快速滴水浸润法和非真空慢速气溶胶浸润法3种方法测定了黑土、褐土、黄土、红壤、紫色土共5种土壤的水稳性团聚体含量.通过配对样本t检验分析了各种方法的稳定性及不同方法的差异性.分析结果表明,非真空快速浸润法测定的各级团聚体含量和总含量均最小,非真空慢速气溶胶浸润法测定的各级团聚体含量和总含量均最大,非真空快速滴水浸润法则介于两者之间.分析了不同方法对团聚体的破坏机制及其适用范围,指出非真空快速浸润法、非真空快速滴水浸润法和非真空快速气溶胶浸润法对团聚体的破坏性呈减小趋势,它们分别适用于暴雨、中雨和小雨等情况.     

缓慢降温对石榴果实冷害发生及生理变化的影响

对缓慢降温处理后石榴果实在冷害温度下的生理反应进行了研究,旨在为石榴果实采后保鲜提供理论依据.以新疆大籽石榴为试材,研究了0℃低温胁迫及缓慢降温对石榴果实采后生理的影响,结果表明:与0℃的低温相比,缓慢降温处理减缓石榴果皮细胞膜透性的升高以及膜脂质过氧化产物丙二醛的积累,抑制了多酚氧化酶活性的增加及减少了酚类物质的氧化,明显推迟和减轻石榴果实冷害症状的发生,减轻了果皮的褐变,保持果实品质.     

矿物包裹型缓释肥料肥效研究

采用微区试验方法,对小试生产的矿物包裹型缓释复合肥料进行了肥效研究.结果表明,缓释肥料与等养分量的复合肥料相比,黑麦草的干物质累积量显著增加,增幅为6.4;～8.1;,缓释肥料的肥效期明显延长、肥料增产效率明显提高.     

绵羊复合微量元素添加剂缓释技术研究

试验证明,绵羊复合微量元素缓释剂溶解速度均衡,在绵羊体内全部溶解需时180～196天,缓冲容量大,无毒副作用,饲用安全可靠,生物效价高,投饲效果显著,能使幼龄羊体增重提高15.74;～31.25;,体长和胸围生长分别提高12.27;和12.11;,羊毛长度增加10.38;,剪毛量提高8.19;,均达到显著水平(P＜0.05).     

炭基复混肥氮钾缓释特性研究

为探究生物质炭及其用量对肥料养分的缓释效果,利用实验室圆盘造粒机制备了生物质炭用量为10%、20%、30%的炭基复混肥,采用土柱模拟淋溶法研究了炭基复混肥在土壤中氮、钾淋出率。结果表明:添加生物质炭能够减少肥料氮、钾淋出量,且随着生物质炭用量的增加炭基复混肥氮、钾素累积淋出率逐渐减小。当第10次淋溶时,生物质炭用量为10%、20%、30%炭基复混肥的氮素累积淋出率分别较不添加处理减少了6.03%、12.49%、33.72%,钾素累积淋出率较不添加处理分别减少了5.15%、5.29%、13.58%,且添加30%生物质炭处理显著大于其他处理。用一级动力学方程、Elovich方程和抛物线方程对各处理养分释放曲线拟合,结果显示一级动力学方程拟合效果最好,可用于表征氮、钾素累积淋出率与时间的关系。      

The pharmacokinetics of a slow-release theophylline preparation in horses after intravenous and oral administration

The pharmacokinetics of a slow-release theophylline formulation was investigated following intravenous and oral administration at 10 mg/kg in horses. A tricompartmental model was selected to describe the intravenous plasma profile. The elimination half-life (t1/2) was 16.91 ± 0.93 h, the apparent volume of distribution (V _d) was 1.35 ± 0.18 L/kg and the body clearance (Cl_B) was 0.061 ± 0.009 L kg^–1 h. After oral administration the half-life of absorption was 1.24 ± 0.30 h, and the calculated bioavailability was above 100%. Thet1/2 after oral administration was 18.51 ± 1.75 h, only a little longer than that after intravenous administration. The slow release formulation did not exhibit any advantage in prolonging thet1/2 of theophylline in the horse.     

Effect of supplemental dietary slow‐release urea on growth performance and physiological status of dairy heifers

We examined the effect of supplemental dietary slow‐release urea on the growth performance and physiological status of 16 dairy Holstein heifers (10 months of age, 322 ± 10 kg). The heifers were offered a formulated isocaloric and isonitrogenous 70:30 roughage : concentrate ration and were assigned randomly to one of four levels of slow‐release urea supplementation (0% [U₀], 1% [U₁], 1.5% [U_1.5] and 2% [U₂] dry matter [DM]). The total study lasted 95 days, which included a 20 days adaptation period. Dry matter intake (DMI) of U₂ was lower than the intakes of U₀ and U₁ (p < .05), while average daily gains (ADG) of U₁ and U_1.5 were higher than U₀ and U₂ (p < .05). Rumen volatile fatty acids concentration did not differ among the four treatments, while ammonia nitrogen concentration increased with an increase in urea level (p < .05). Serum blood urea nitrogen concentration was lower in U_1.5 than in U₀ and U₂ while serum free fatty acids concentration in U₂ was higher than in the other three treatments (p < .05). We concluded that the addition of urea at a level of 1.5 to 2.0% DM resulted in a reduction in DMI but the addition of 1.0%–1.5% urea resulted in the highest ADG, with no negative effects on rumen fermentation and health status of the calves.