Decomposition responses of pine (Pinus massoniana) needles with two different nutrient-status to N deposition in a tropical pine plantation in southern China

? The effect of nitrogen (N) deposition on the decomposition of pine (Pinus massoniana) needles in a tropical pine plantation was studied. The pine needles with two different nutrient status (nutrient-rich and nutrient-poor) were used, followed by 3-levels of N treatments (Control: no N addition, Low- N: 5 g N m^?2 y^?1, and Medium-N: 10 g N m^?2 y^?1 experimental inputs), which had been applied for 26 months continuously before this experiment and continued throughout the decomposition measurement.

? The main objective was to test the hypothesis that decomposition of nutrient-rich needles would be more sensitive to cumulative N deposition than the decomposition of nutrient-poor needles.

? Nitrogen addition had negative effect on mass loss, and the release of N and P from decomposing nutrient-rich needles but little or no effect on the decomposition of nutrient-poor needles. In addition, a negative effect in the initial decomposition phase and a positive effect in later decay stages were found on C release. The negative effect was stronger on nutrient-rich needles than on nutrient-poor needles, but the reverse was true for the positive effect.

? Our results suggest that response of litter decomposition to N deposition may vary depending on the nutrient status of the litter.

     

海藻酸钠和壳聚糖对莲藕贮藏效果及品质的影响

在常温（25℃）条件下,采用不同浓度的海藻酸钠（SA）和壳聚糖（CTS）涂膜保鲜剂对莲藕进行处理,对其采后贮藏效果和品质进行研究。结果表明：适宜浓度的SA 和CTS 涂膜处理可以有效的抑制莲藕表皮褐变,减小失重率,显著抑制莲藕VC、可溶性糖含量的降低和细胞膜透性升高。其中1.0%SA 处理在抑制莲藕表皮褐变,减小失重率,抑制可溶性蛋白含量降低及细胞膜透性上升等方面表现最好;1.25% CTS 和1.5% CTS 处理在抑制莲藕VC 和可溶性糖含量降低方面表现较好。     

两系杂交稻新组合Y两优7238的选育及制种关键技术

肇庆市农业科学研究所与中国种子集团有限公司共同选用优质常规水稻品种五山油占和抗稻瘟病恢复系R238进行杂交选育出恢复系R7238,再利用光温敏核不育系Y58S与恢复系R7238选配出两系杂交稻新组合Y两优7238。该组合比对照增产达极显著水平,米质达省标优质三级,中抗稻瘟病和中感白叶枯病,一定程度上解决了杂交水稻组合在高产、抗病和优质三方面相结合的技术难题,于2012年6月通过广东省农作物品种审定。介绍了Y两优7238的选育过程、品种主要特征特性和高产制种关键技术。     

步进式水田中耕除草机的研制与试验

为解决水田的除草问题,增加现有机具的作业功能,该文在步进式插秧机底盘结构的基础上,研制了一种步进式水田中耕除草机。该机由步进式插秧机底盘提供动力,主要由机架、传动系统、仿形及耕深调节机构以及复合式除草部件指辊和刀辊等组成,可实现对杂草的拉拔和埋压。田间试验结果表明:该机配备复合式除草部件、工作速度为0.5m/s、除草深度为50mm时,行间除草率为83.7%,伤苗率为4.1%,可在草量多、杂草高的水田中进行有效除草。     

肇庆地区作物病虫害辅助诊治网络系统的构建与应用

在调查、研究肇庆地区农作物病虫害发生特点、辅助诊断与防治方法的基础上,以软件工程理论、LUBAN模型为基本方法及以ASP SQL SERVER为开发工具,研究构建了肇庆地区作物病虫害辅助诊治网络系统并进行初步运行,结果表明,该系统是一个针对肇庆地区农作物病虫害进行辅助诊治以及相关信息浏览、查询和编辑的网络型农业专家系统,可为肇庆及周边地区的农户提供农作物病虫害远程诊治及信息浏览与查询服务,具有良好的应用前景.     

中国南亚热带三种不同林型下土壤应对酸沉降的响应

Long-term changes in soil pH, the current status of soil acidification, and the response of bulk soil and soil water pH to experimental nitrogen addition under three subtropical forests were investigated in Dinghushan Biosphere Reserve of subtropical China. The results showed that the mineral soil pH at 0-20 cm depth declined significantly from 4.60-4.75 in 1980s to 3.84-4.02 in 2005. Nitrogen addition resulted in the decrease of pH in both bulk soil and soil water collected at 20-cm depth. The rapid decline of soil pH was attributed to long-term high atmospheric acid deposition (nitrogen and sulphur) therein. The forest at earlier succession stage with originally higher soil pH appeared to be more vulnerable to acid deposition than that at later succession stage with originally low soil pH.     

磷添加对南亚热带森林土壤有机碳氮矿化影响的培养实验研究

采用室内培养的方法,分析了磷添加对南亚热带鼎湖山马尾松林（PMF）、针阔叶混交林（PBMF）和季风常绿阔叶林（MEBF）土壤（0～10cm）CO小CH4排放／吸收和有机氮矿化的影响。结果表明：28周的培养,100mg磷添加处理土壤C—CO2累积排放量依次为PMF、PBMF和MEBF对照的82．4％、84．4％和102．8％,2000mg磷处理土壤依次为其对照的107．2％、101．2％和109．1％;100mg磷处理土壤CH4累积排放量依次为其对照的69．9％、102．7％和66．3％,2000mg磷处理土壤依次为其对照的-57．4％、25．3％和22．4％,其中,磷在处理初期较一致的提高土壤CO2和CH4排放,磷对土壤有机碳矿化的影响与森林的土壤状况有关,添加的磷浓度越高,其促进作用越强。1周的培养,100mg磷处理土壤有效氮净矿化量依次比PMF、PBMF和MEBF对照少37．06％、39．60％和28．62％,2000mg磷处理土壤依次比其对照少70．97％、84．14％和187．97％,100mg磷处理土壤硝态氮净矿化量依次比其对照少48．06％、40．45％和28．03％,2000mg磷处理土壤依次比其对照少254．09％、115．32％和238．50％,磷显著的抑制土壤有机氮的矿化和硝化。结果建议,在研究P对土壤有机碳氮矿化过程时应充分考虑土壤对P的吸附作用。     

氮磷钾配施对油麦菜肥料效应及硝酸盐含量的影响

通过对油麦菜(Lactuca sativa L.)进行"3414"测土配方施肥试验,研究了氮、磷、钾配施对油麦菜肥料效应及硝酸盐含量的影响.结果表明,油麦菜氮、磷、钾肥料效应函数为y=25 177.4+282.08 N-0.918 N2-110.76 P-2.649 P2+485.94 K-2.932 K2+1.347 NP-1.641 NK+2.233 PK;N2P2K2配施的产量和收入最高,且硝酸盐含量较低,产量比常规处理增加36.6%,收入比常规处理增加38.8%,硝酸盐含量比常规处理减少39.0%     

鼎湖山地区大气颗粒物中水溶性无机盐粒径分布特征

为研究珠江三角洲大气颗粒物的化学组成特征及其来源,2008年10-11月在中科院华南植物研究所鼎湖山区域大气本底观测站对大气中的颗粒物进行了分级（8级）采样,并对各个粒径段颗粒物中水溶性无机盐进行了分析。结果表明,SO42-、NH4+在小于1.1μm的细粒子中出现浓度峰值;Na+和Cl-在1.1-2.1μm出现浓度峰值;NO3-分别在1.1-2.1和3.3-4.7μm出现两个浓度峰值;K+在0.65-1.1和5.8-9μm两个粒径段出现峰值;而Ca2+和Mg2+的浓度峰值则出现在大于9μm粒径段。     

仔猪先天性震颤的病理组织学诊断

利用病理组织学方法对仔猪先天性震颠病病例进行诊断。病理组织学主要变化为大脑软脑膜血管充血,脑膜下水肿;大脑白质和脊髓部位的有髓神经髓鞘发育不全,横切面可见神经髓鞘相对数量少,疏密、大小不均,形态差别大。其他脏器见继发性细菌感染病变。