铺地竹叶片对结球生菜种子发芽及幼苗生长的影响

采用基质盆栽试验,研究了铺地竹(Sasa argenteastriatus E.G.Camus)叶片对结球生菜(Lactucasativa L.var.capitata L.)种子萌发和幼苗生长的影响,结果表明,铺地竹叶片粉末对结球生菜种子的萌发和幼根生长具有一定的抑制作用,随着浓度的增加抑制作用增强,在50～200 g/m2的范围内,幼根抑制率为12.15%～28.91%。在50～100 g/m2的用量下,铺地竹叶片对结球生菜苗长表现为促进生长作用,而在200 g/m2时,则表现为抑制生长作用。施用铺地竹叶片后3 d、6 d、9 d和12 d,结球生菜幼苗的叶绿素含量特别是叶绿素a的含量显著减少,随着基质中叶片粉末浓度的增加,结球生菜叶绿素含量降低,叶绿素a含量高低依次为对照、低浓度处理、中浓度处理、高浓度处理。随着处理后时间的延长,竹叶对结球生菜叶片叶绿素a含量的影响减弱。这个结果进一步验证了自然条件下铺地竹叶片对植物生长的化感效应,说明其具有开发植物源除草剂的潜力,为研究铺地竹叶片中的化感物质提供了佐证。     

丘陵山地水田旱地交错分布区耕地地力评价

在自然条件下,通过比较水田和旱地地块的肥力差异,选择合适的评价模式,以制定合理的耕地利用依据。结合研究区丘陵山地水田和旱地交错的分布特点,依据最小控制斑块面积确定评价单元数,重点分析了水田和旱地在实际耕作中的差异性,并结合操作实践合理分配水田和旱地在评价体系中各指标的权重系数。结果表明,评价单元数的多少对评价结果的影响比较明显,综合研究区耕地地力实际情况和节约计算耗时的实际,建议最小控制斑块面积在临界值(推荐值)的10%为佳;另外通过水旱分开评价和水旱统一评价两种评价模式的比较,发现水旱分开能使评价结果更加贴近实际情形,反映实际耕地地力状况,能够更加有效地指导农业生产实践。     

Cell direct reprogramming：a new technique for treating diabetes

Diabetes is characterized by an absolute or relative deficiency in β-cell mass, which cannot be reversed with existing therapeutic strategies. The restoration of the endogenous islet β-cells can stabilize the level of blood glucose. The islet β-cells can be obtained from the directional differentiation of stem cells, but the process is complex and has the risk of teratomas generation. Cell direct reprogramming, one terminal differentiated cell can transdifferentiate into another kind of terminal differentiated cell, which is other than directional differentiation from stem cells. Direct reprogramming gives rise to the generation of islet β-cells from one terminal differentiated cell, may be preferable for diabetes therapy because of its unique advantage.     

机械化直播油菜的优点及高产栽培技术

针对近年来油菜生产机械化程度低、用工多、成本高、效益低、面积逐年萎缩的情况,通过多年试验与总结,探索与完善了机械化直播油菜的高产栽培技术,实现了省工节本、提高机械化水平的目的,也为大面积油菜生产提供技术参考。     

调环酸钙25%悬浮剂对直播稻抗倒伏和产量性状的影响

为了研究新型植物生长调节剂调环酸钙在直播稻上的应用效果,本研究设计了调环酸钙25%悬浮剂在直播稻武运粳8号上的田间试验,用来了解其对直播稻的抗倒伏性状和产量性状的影响。试验结果表明:在直播稻武运粳8号的分蘖期使用调环酸钙25%悬浮剂12~15g/667m2均能够显著降低水稻的株高,缩短茎基部节间长度,提高水稻的抗倒伏能力,同时也能显著提高水稻产量。     

防洪堤施工中筑堤粗粒土控制干密度的合理性分析

文章对相对密度控制问题进行分析,并提出几点建议。     

深两优5814作烟后稻旱育抛秧高产栽培技术

深两优5814系国家杂交水稻工程技术研究中心深圳清华龙岗研究所用"Y58S"与自选"恢复系丙4114"组配选育的优质、高产、抗病的两系超级杂交水稻新品种,属弱感光型。2009年宁化县引进种植,根据其特征特性并结合宁化县的气候条件,总结深两优5814作烟后稻旱育抛秧高产栽培技术。     

Associations between postpartum diseases and milk yield and changes in body condition between drying off and parturition of dairy cows in Argentina

ABSTRACT

Aims: To assess the change in body condition score (BCS) during the early and late dry periods and its association with postpartum diseases and milk yield in grazing dairy cows from central Argentina.

Methods: BCS assessments during the dry period, and cow health and milk production records up to 90 days in milk (DIM), were collated for cows from 28 farms at monthly visits between 2007 and 2008. Cows were categorised into four groups; those in Group 1 (n=7,067) maintained or gained BCS during the early and late dry periods; Group 2 (n=2,615) maintained or gained BCS during the early dry period and lost BCS during the late dry period; Group 3 (n=1,989) lost BCS during the early dry period and maintained or gained BCS during the late dry period; and Group 4 (n=5,144) lost BCS during the early and late dry periods.

Results: Cows in Group 1 had reduced odds of having retained fetal membranes (RFM), metritis, and clinical mastitis up to 90 DIM than cows in Group 2 (p<0.001), but the odds of disease were similar to cows in Group 3. The odds of having RFM or clinical mastitis tended to be lower in cows in Group 1 than cows in Group 4 (p=0.08). The odds of cows being culled or dying during the first 90 DIM were lower for cows in Group 1 than for those in Groups 2, 3, and 4 (p≤0.05). Mean accumulated milk yield up to 90 DIM was higher in cows in Group 1 than Group 2 and Group 4 (p<0.001), but was similar to that of cows in Group 3 (p=0.28).

Conclusions and clinical relevance: Cows that lost BCS during the late dry period had increased odds of being diagnosed with several postpartum diseases and had decreased milk yield compared to cows that maintained or gained BCS during the entire dry period. Loss of BCS during any stage of the dry period was also associated with increased incidence of culling or death during the first 90 DIM. These results should raise awareness among dairy cattle producers of the importance of properly managing cow body condition during the dry period, especially during the late dry period.     

云南芥菜型油菜资源品质及苗期耐旱性评价

为研究芥菜型油菜的耐旱性，对150份云南芥菜型油菜地方品种的品质及苗期不同干旱程度下植株地上 及地下部进行研究。结果表明，参试芥菜型油菜耐旱性总体表现较好，品质变异丰富，其中油酸、芥酸变异系数大 于1，依据品质性状参试品种大致聚为三类；中度及重度干旱均能显著影响油菜地上部及根系的生长，其中对根系 影响更大；各品质性状与耐旱性相关分析表明，中度干旱条件下，耐旱性与含油量及芥酸、花生烯酸2种极长链脂肪 酸呈显著正相关，与5种长链脂肪酸硬脂酸、棕榈酸、油酸、亚油酸、亚麻酸为显著负相关，而重度干旱条件下均不相 关，同一品种在不同程度干旱下其耐旱性有差别；含油量与极长链脂肪酸呈显著正相关，与长链脂肪酸及蛋白含量 呈显著负相关，极长链脂肪酸与长链脂肪酸间呈极显著负相关。共筛出8个综合耐旱性强的材料。     

不同沟垄覆盖下土壤水热效应对旱作马铃薯生长及产量的影响

针对宁南山区春季降雨少、低温不利于马铃薯出苗,而作物生育中后期高温胁迫限制马铃薯块茎形成导致减产等问题,于2016年设置垄覆地膜沟内覆盖塑料地膜(DM)、玉米秸秆(JG)、生物降解膜(SM)、麻纤维地膜(MM)、液态地膜(YM)及沟不覆盖(BM),以传统平作为对照(CK),研究沟垄覆盖模式对土壤温度、土壤水分、旱作马铃薯生长及块茎产量的影响.结果表明:处理DM,SM,MM和YM马铃薯生育期耕层土壤温度表现出增温效应,而处理JG和BM表现为降温效应,其中处理DM增温效果和处理JG降温效果最佳.处理YM,JG对马铃薯生长前期保水效果较好,分别较CK显著提高13.3%,27.0%,而处理JG,DM对生育中后期的保墒效果较佳,分别较CK显著提高22.4%,13.2%.处理JG可显著促进马铃薯生长,其增产效果最为显著,DM次之,分别较CK增产47.8%,44.8%,其他处理较CK差异不具有统计学意义.可见,在宁南山区实施垄覆地膜沟覆秸秆模式可调控土壤水热环境,对旱作马铃薯生长及增产效果最佳.