The priority of management factors for reducing the yield gap of summer maize in the north of Huang-Huai-Hai region,China

Understanding yield potential, yield gap and the priority of management factors for reducing the yield gap in current intensive maize production is essential for meeting future food demand with the limited resources. In this study, we conducted field experiments using different planting modes, which were basic productivity(CK), farmer practice(FP), high yield and high efficiency(HH), and super high yield(SH), to estimate the yield gap. Different factorial experiments(fertilizer, planting density, hybrids, and irrigation) were also conducted to evaluate the priority of individual management factors for reducing the yield gap between the different planting modes. We found significant differences between the maize yields of different planting modes. The treatments of CK, FP, HH, and SH achieved 54.26, 58.76, 65.77, and 71.99% of the yield potential, respectively. The yield gaps between three pairs: CK and FP, FP and HH, and HH and SH, were 0.76, 1.23 and 0.85 t ha~(–1), respectively. By further analyzing the priority of management factors for reducing the yield gap between FP and HH, as well as HH and SH, we found that the priorities of the management factors(contribution rates) were plant density(13.29%)fertilizer(11.95%)hybrids(8.19%)irrigation(4%) for FP to HH, and hybrids(8.94%)plant density(4.84%)fertilizer(1.91%) for HH to SH. Therefore, increasing the planting density of FP was the key factor for decreasing the yield gap between FP and HH, while choosing hybrids with density and lodging tolerance was the key factor for decreasing the yield gap between HH and SH.     

中国畜牧业生产波动的特征及路径识别

基于1978—2016年畜禽产品年度产量数据,采用HP滤波技术和非线性MS-AR模型,分析中国畜牧业生产波动的特征,从畜牧业生产区制转换的视角剖析畜牧业生产波动的具体路径,探讨影响畜牧业生产波动和路径转换的原因。结果表明:从生产波动变化趋势上看,猪肉生产增长高峰期出现最早,其次是牛肉、羊肉、禽肉和禽蛋生产,牛奶生产增长高峰期出现时间最晚;从生产波动比较上看,猪肉生产波动幅度最小,其他畜牧产业生产波动幅度相对较大,各畜牧产业生产波动趋势存在差异,但近年来总体趋于收敛。通过模型识别将畜牧业生产划分为低速、中速和快速增长3个区制,低速和中速增长区制下各畜禽业产品产量平均增长率在3%和5%左右,而快速增长区制下平均增长率在10%以上;猪肉生产倾向于保持中速增长,牛肉、羊肉和牛奶生产容易出现低中速增长往复徘徊的现象,禽肉和禽蛋生产在各区制下均较为稳定且区制变迁较为平稳;改革开放以来,除牛奶产业以外,其他畜牧产业生产基本在低速或中速增长区制时间最长。基于此,提出针对不同畜禽产业在不同发展阶段相机制定不同调控政策,推动畜禽产业规模化养殖和产业化经营水平,提高畜禽产业抗冲击能力等建议。     

贵州柳杉云毛虫发生特点与防治

为了有效控制柳杉云毛虫Hoenimnema roesleri Lajonquière在贵州的发生、危害及蔓延,对柳杉云毛虫的生物学习性进行了初步调查,对其形态进行了描述,对其防治效果进行了后续观察,总结提出了化学、人工、营林相配套的综合防治技术措施。     

甘蓝型油菜耐低温生长生理生化响应机制

为提高甘蓝型油菜耐寒育种过程中的筛选效率，研究甘蓝型油菜耐低温机理，以8个不同抗寒性的甘蓝型油菜为材料，对低温条件下各材料的生物量、叶绿素、脯氨酸和相对电导率进行测定，发现在室外平均气温2.75℃时，抗性材料的生物量、叶绿素和脯氨酸的累积量都显著高于敏感材料，相对电导率没有显著差异；当平均气温7.52℃回升至12.39℃，抗性材料和敏感材料生物量的累积量无显著差异；在恒定低温10℃/4℃处理下抗性材料和敏感材料在处理前3周生物量均持续累积，但从第4周开始敏感材料新叶出现白斑，生物量减少，抗性材料老叶出现白斑，生物量维持不变。结果表明，耐低温材料在低温条件下叶绿素含量受到的影响较小，脯氨酸的积累量持续上升，具有较强的快速适应能力，在低温下具有显著的持续生长优势。     

新型国产白油佐剂与进口Marcol-52白油佐剂配制疫苗的比较试验

The Newcastle disease inactivated vaccines were prepared with oil adjuvants respectively from domestic and import.The experiments were done in order to compare the new domestic oil and Marcol-52 according to a series of testing indexes. The results showed that the quality of the new domestic oil was better than Marcol-52, except the absorptive quality.     

多不饱和脂肪酸的生物学功能及其在动物生产中的应用

多不饱和脂肪酸(PUFA)是一种重要的营养物质,是细胞膜磷脂的重要组成成分,在生物系统中具有广泛的生物学功能,能够调节机体的脂类代谢、免疫,具有抗癌、预防和治疗心血管疾病、促进机体生长发育以及调控基因的表达等功能。本文就多不饱和脂肪酸的来源及生物学功能进行阐述,并浅谈了多不饱和脂肪酸在动物生产中的应用现状及前景。