NO3--N/NH4+-N配比对小白菜生长及硝酸盐含量的影响

利用NO3^--N/NH4^＋-N不同配比的营养液对11个小白菜品种进行水培试验。结果表明,不同的NO3^--N/NH4^＋-N配比对不同品种小白菜生长和的硝酸盐含量有着显著的影响,同一氮源培养下不同的小白菜品种间表现出显著的差异,在5.0∶5.0（B）处理条件下,各品种小白菜表现良好;供试的小白菜品种的硝酸盐积累量随着铵态氮比例的增加而下降,表明适当地配施铵态氮较纯硝态氮营养液培养小白菜能获得较低的硝酸盐积累量,但不影响生长。     

扬州砂壤土对水溶性磷吸附与固定的示踪动力学研究

本研究应用分级提取法测定了水溶性标记磷在水田和旱田条件下的扬州砂壤土中，吸附态磷和固定态磷（包括Ａｌ－Ｐ、Ｆｅ－Ｐ和Ｃａ－Ｐ）含量随时间的变化动态，结果表明：（１）吸附态磷和Ａｌ－Ｐ含量随时间的推移首先迅速上升并在几天内达到高峰，然后逐步下降，而Ｆｅ－Ｐ、Ｏ－Ｐ及Ｃａ－Ｐ则一直处于上升趋势，但上升的幅度随时间的推移而逐步减小。（２）在同一耕作条件下，吸附态Ｐ和Ａｌ－Ｐ含量一般高于Ｆｅ－Ｐ、Ｏ－Ｐ的含量，且Ｃａ－Ｐ的含量很小。本研究还应用对土壤中标记磷的连续提取示踪动力学分析法，定量研究了吸附态标记磷和固定态标记磷在提取剂中的溶解度随时间的变化动态。结果表明，（１）随时间的推移，吸附态和固定态磷的溶解度均逐步下降。（２）在旱田条件下，吸附态标记磷的解吸速度在单位时间内的平均下降幅度大于水田条件，而固定态磷的溶解度在单位时间内的平均下降幅度略低于水田条件     

寡齿新银鱼卵细胞粘丝的亚显微结构

经电镜扫描寡齿新银鱼的第Ⅳ时相，第Ⅴ时相卵母细胞和受卵的卵细胞粘丝，结果表明，卵细胞表面具从受精孔发生的１２根左右粘丝，此粘丝于受精孔处微弱弯曲，经侧部渐向受精孔相对处呈现很强扭曲或互相缠绕。卵细胞粘丝不仅出现在受精卵和第Ⅴ时相卵母细胞表面，而且清晰地出现在第Ⅳ时相卵母细胞的滤泡膜上。     

“此时无声胜有声”──无声语言在体育教学中的运用

“无声语言”就是指人们说的眼神、手势、体态、表情等。在以体育运动为媒体的教学过程中．直观教学占主导地位。教师与学生双方则是一种人与人之间的交往关系,其方式不单有语言的,而且有非语言的,这就是无声语言教学方式。     

封育条件下草地光谱反射特征及地上生物量估测

2005年7月至2006年4月,对云南省马龙县封育草地和过牧草地的光谱反射率、草层高度、覆盖度和地上生物量进行了测定,分析了归一化植被指数(NDVI)及比值植被指数(RVI)与地上生物量之间的相关性。结果表明:过牧草地封育1年之后,其草层高度、覆盖度和地上生物量显著增加,光谱反射特征也相应地发生明显变化。450~850 nm范围内,两种草地不同季相条件下在各波段的光谱反射率差异均达到极显著水平(P<0.01),覆盖度及季节变化对近红外波段的影响明显大于可见光波段。旺盛生长期(7月)和枯黄期(11月),封育草地具有植被反射型特征,而自由放牧草地表现为植被-土壤型;返青期(4月)两种草地均表现为土壤型。过牧草地地上生物量与两种植被指数之间无显著相关性。封育草地地上生物量与NDVI,RVI之间存在显著的(P<0.05)非线性相关,旺盛生长期和返青期NDVI与地上生物量的相关性强于RVI,枯黄期RVI与地上生物量相关性强于NDVI。     

超声波辅助提取茶籽多糖工艺条件的研究

本文利用超声波结合正交试验的方法研究了超声波对茶籽多糖提取条件的影响.结果表明:在试验条件限定的范围内,对浸出率影响顺序为固液比＞温度＞功率＞时间.根据各因素不同水平均值多重比较(SSR)可知,当浸提功率400W、固液比1:40、温度60℃、浸提时间5min的浸提条件最合适.而超声波辅助提取对茶籽多糖清除*OH的能力影响不显著,而对茶籽多糖清除O2.ˉ的能力有较好的增强作用.     

Distribution and migration of Japanese common squid, Todarodes pacificus, in the southwestern part of the East (Japan) Sea

Data on squid catches of Korean and Japan, water temperatures at depth of 100 m, and night-visible images of fishing boats collected in the East (Japan) Sea from 1970 to 1999 were analyzed to examine the distribution and migration of the Japanese common squid, Todarodes pacificus, in the southwestern part of the East (Japan) Sea. The main fishing grounds detected from squid catch in each grid (0.5° latitude × 0.5° longitude) by Korean squid fishery and night-visible images provided by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) were situated in the southwestern part of the East (Japan) Sea. The distribution and migration route was illustrated from squid catch in each grid and DMSP OLS image. In years of high catches, the fishing grounds were situated mainly between Ulleung Island and the eastern coastal waters of Korea, while in years of low catches they were situated between Ulleung Island and the Yamato Bank in the central East (Japan) Sea. The center of fishing activity began moving northward from around the Korea/Tsushima strait to the northern boundary of the Tsushima Warm Current in March, reaching into the Yamato Bank in September, and then returning to the strait by February. The northward and southward migration routes differed; the northward migration route occurred closer to the mainland coast of Korea than the southward migration route did. This work suggests T. pacificus begin their northward migration almost 2 months earlier than previously suggested.     

2008－2018年拉萨市温室蔬菜地时空变化特征

随着居民对蔬菜消费需求的不断提高,拉萨市温室蔬菜地得到快速发展,但对温室蔬菜地格局变化过程仍缺乏清楚的认识。该研究基于2008－2018年11期拉萨市高清遥感影像,结合实地调研,采用重心转移分析、地统计分析等方法,研究了2008－2018年拉萨市温室蔬菜地时空格局变化特征。结果表明：1）2008－2018年,拉萨市温室蔬菜地面积总体呈波动上升趋势,年均增长率为6.93%。研究时段内,温室蔬菜地变化经历了发展、调整、稳定三个阶段,各阶段年均变化率分别为11.08%、-2.13%和0.77%。2）研究时段内,拉萨市城关区和堆龙德庆区温室蔬菜地比例下降56.2%,达孜区和曲水县温室蔬菜地比例上升51.58%,温室蔬菜地分布重心向远离城区的城郊转移,向东南方向迁移了约4 896 m。3）新增温室蔬菜地向高海拔和大坡度区域转移,海拔3 675～3 800 m范围内温室蔬菜地面积比例由22.05%上升到30.41%,坡度6°～10°区域温室蔬菜地面积占比上升5.92%。4）温室蔬菜地新增源于耕地,减少多因为建设用地扩张。蔬菜需求量大和温室蔬菜收益高是温室蔬菜地面积增加的基本动力,区域土地利用调整是温室蔬菜地格局变化的重要推动力。     

基于模糊算法的温室番茄调亏滴灌制度综合评判

该文研究利用改进的模糊综合评判模型在温室滴灌番茄生长、产量、品质和耗水进行综合评判的可行性。于2015和2016年在中国农业科学院新乡综合试验基地的日光温室内,以滴灌番茄为研究对象,参考20 cm标准蒸发皿的累积蒸发量,分别在开花坐果期和成熟采摘期进行充分灌溉、轻度亏缺和中度亏缺,采用改进的模糊综合评判模型,对调亏灌溉制度温室番茄的生长指标、产量指标、耗水指标和品质指标进行综合评价。结果表明:不考虑阶段水分亏缺条件下,番茄的生长指标、产量指标和蒸发蒸腾量指标均随灌水量的增大而增大,品质指标则相反。轻度亏缺对番茄品质指标的影响较小(两者的品质综合评判指数为0.135和0.138,0.125和0.124),采摘期轻度亏缺的生长指标和产量指标的综合评判指数高于花果期轻度亏缺处理,且全生育期蒸发蒸腾量较低;花果期中度亏缺的产量指标和品质指标的综合评判指数与采摘期中度亏缺相近,但前者的总蒸发蒸腾量低于后者。因此,推荐水资源充足地区可采用在成熟采摘期轻度亏缺的灌溉模式,而水资源短缺地区采用在开花坐果期中度亏缺的灌溉模式。研究可为温室调亏滴灌制度的优化提供参考。     

Role of nitrogen supplementation in alleviating drought‐associated growth and metabolic impairments in Phoebe zhennan seedlings

Drought is one of the major environmental stresses altering forest productivity. However, nutrient availability can modulate drought resistance. Phoebe zhennan (gold Phoebe) is a high‐quality timber‐producing but threatened tree species in China, facing serious anthropogenic disturbances and abiotic constraints that restrict its growth and development. However, little attention has been given to designing adaptive strategies for its management by evaluating the possible role of major nutrients, particularly nitrogen (N), on its morphological and physio‐biochemical responses under water stress. To evaluate these responses, a complete randomized design was followed to investigate the effects of two irrigation levels (well‐watered and drought‐stressed conditions) and N fertilization treatments (with and without N). Drought stress significantly affected the growth of seedlings, as indicated by impaired photosynthesis, pigment degradation, disrupted N metabolism, over‐production of reactive oxygen species and enhanced lipid peroxidation. Nitrogen supplementation under drought stress had remarkable positive effects on the growth through physio‐biochemical adjustments as shown by higher level of nitrogenous compounds and up‐regulation of N‐associated metabolic enzymes activities which might be due to N‐mediated improved leaf relative water contents and photosynthetic efficiency. In addition, N application reduced oxidative stress and membrane damage, and maintained a high accumulation of osmolytes. However, in well‐watered seedlings N fertilization significantly improved root biomass and net CO₂ assimilation rate suggesting high N‐use efficiency of the seedlings. These findings reveal that drought significantly affects the growth of P. zhennan, while N fertilization plays a crucial role in alleviating water stress damage by improving its drought tolerance potential at low metabolic costs. Therefore, N fertilization could be considered as an effective strategy for the conservation and management of P. zhennan in the face of future climate change.