落桦混交林幼龄期Ⅰ级木分布规律研究     

刘群舫  刘国英  徐士瑞 《河北林果研究》1996,(1)

利用３６块落叶松一样树混交林标准地调查资料，研究其幼龄期林分Ⅰ级木单位面积株数与林分密度之间的关系，结果表明：Ⅰ级木的株数并非随密度的增加而直线递增，而是趋向“二阶常数”分布，且在同一年龄阶段，在较低的密度范围（２３２５～４８００株／ｈｍ２）或较高的密度范围（４８０１～６７５０株／ｈｍ２）．Ⅰ级木的株数变动幅度不太大。  相似文献   

Reproductive biology of the female Japanese mantis shrimp Oratosquilla oratoria (Stomatopoda) in relation to changes in the seasonal pattern of larval occurrence in Tokyo Bay, Japan     

Keita  KODAMA  Takamichi  SHIMIZU  Takashi  YAMAKAWA  Ichiro  AOKI 《Fisheries Science》2004,70(5):734-745

ABSTRACT:   The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length ( BL ) < 8 cm. Fecundity was expressed as a function of BL , ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL . Small female shrimps (<10 cm BL ) spawned around August. Most large female shrimps (≥10 cm BL ) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July.  相似文献   

新疆淡水藻类研究：乌鲁木齐南山八一林场绿藻初报     

王克勤 《干旱区研究》1997,14(4):26-29

本文首镒报道乌鲁木齐南山八一林场山区的绿藻１１属，１２种，其中１０属，１０种为新疆新记录。这些结果是对１９９１年７月采集的２０号标本经鉴定后获得的。  相似文献   

披碱草和野大麦杂种F1与BC1F1代的生物学及农艺特性研究     

李造哲  于卓  马青枝  王俊杰 《中国草地学报》2004,26(5):9-14

对披碱草和野大麦及其杂种F1与BC1F1代的生物学及农艺特性进行了分析比较。结果表明,亲本野大麦生长发育节律较快,较早地开花结实,果后营养期较长,生育期74d,生长天数达206d,具有很强的分蘖能力;披碱草生长发育节律较慢,生育期124d,生长天数193d;杂种F1的生长天数介于双亲之间,生长动态偏向亲本披碱草,分蘖能力介于双亲之间;BC1F1代生长发育节律较F1代提早,不同株系生长天数不同,生长动态偏向轮回亲本野大麦,分蘖能力有较大的变异。杂种F1代表现出较强的杂种优势,BC1F1代产草量较F1代有所降低,不同株系间存在明显的差异。总体上,BC1F1代的生产性能倾向于轮回亲本野大麦。  相似文献   

Effect of Human Menopausal Gonadotropin,17β-estradiol and Epidermal Growth Factor on the Quality of in vitro Maturation Bovine Oocytes     

TANG Shuang  AN Wen-zhong  JIANG Xin-long  LI Xiang-chen 《中国畜牧兽医》2016,43(6):1585-1590

For optimizing in vitro maturation system of bovine oocytes,we firstly examined the influence of four different hormonal regimes(FSH+LH,HMG,FSH+LH+E₂ and HMG+E₂) on oocyte maturation rates.Then we studied the effects of epidermal growth factor (EGF) in the above defined medium on bovine oocyte maturation,in vitro development and quality of parthenogenetic embryos.The cell apoptotic index of parthenogenetic blastocysts was detected by TUNEL.No significant difference was observed in maturation rates in four groups supplemented with different hormones.However,human menopausal gonadotropin (HMG) provided steady maturation results in replicates.Maturation of oocytes was promoted by supplementation with 17β-estradiol (E₂).Combination of HMG and E₂ gave rise to steady and efficient mature results.The presence of EGF at 30 ng/mL concentration significantly increased maturation rate and blastocyst rate and reduced apoptotic cells in parthenogenetic blastocysts.Therefore,the optimal oocyte maturation solution could be supplemented with 0.075 IU/mL HMG,1 μg/mL E₂ and 30 ng/mL EGF.  相似文献   

格木寄生线虫中国新记录种——卡勒萨隐皮孢囊线虫Cryphodera kalesari     

王宏洪  蔡润得  黄少彬  廖金铃 《植物保护》2019,45(5):178-185

在对广东省主要珍贵树种上的线虫进行调查时从格木Erythrophleum fordii上分离到一种隐皮孢囊线虫,经形态特征观察和测量数据分析,将其鉴定为卡勒萨隐皮孢囊线虫Cryphodera kalesari。其诊断特征为:雌虫椭圆形至近球形,头部具有1个唇盘和2～3个唇环,口针长33.6～37.8μm,阴门唇突出,阴门与肛门之间区域凹陷,肛阴距为42～72μm;2龄幼虫头部具1个明显的唇盘和3个唇后环纹,口针长24.8～29.5μm,口针基部球前缘凹陷,侧区3条侧线,尾长圆锥形,长38～53.5μm,尾末端细圆,透明尾长17.1～25.1μm,侧尾腺孔位于肛门后2～5环;雄虫未发现。本研究首次获得了卡勒萨隐皮孢囊线虫的rDNA(LSU D2D3和ITS)序列,为此线虫的鉴定提供了可靠的分子数据。本研究还分析了卡勒萨隐皮孢囊线虫与本属其他种类的系统进化关系。卡勒萨隐皮孢囊线虫为中国的地理新记录种。格木为隐皮孢囊线虫的新寄主。  相似文献   

两系杂交油菜早中熟组合精量直播栽培性状比较研究     

潘典进  罗传贵  杨玲丹  云琴  王军华  龚元春  黄春祥 《现代农业科技》2015,(2):13-14

开展优质核不育两系杂交油菜早中熟新组合比较试验,结果表明:2种熟期类型杂交组合间产量差异明显,中熟组合单位面积产量极显著高于早熟组合,对比分析产量构成因子,主要是平均角粒数多和千粒重重,2种熟期类型组合间株高和一次分枝数差异较小,油菜菌核病感病程度中熟组合相对较轻。因此,油菜生产不可一味选择和使用早熟类型品种或组合,不然将较难获得理想产量和生产效益。  相似文献   

Short‐term releases of CO2 from newly mixed biochar and calcareous soil          下载免费PDF全文

R. Cardelli  M. Becagli  F. Marchini  A. Saviozzi 《Soil Use and Management》2016,32(4):543-545

The work aimed to quantify native organic C mobilized in one calcareous soil in the 21 days after addition of biochar at a range of large to very large applications. The experiment was carried out in unplanted microcosms, and CO₂ flux was used as a measure of net mineralization. A rapid methodological approach, which does not require ¹³C as a tracer, was used to assess any priming effects induced by the biochar. The amount of CO₂‐C mobilized was small relative to the amount of biochar C and proportional to the amount of the biochar added. The additional CO₂‐C was similar to the content of the water‐soluble organic carbon in the biochar added with each application. No interaction with native soil C, that is priming effect, was observed.  相似文献   

浙江乌牛早春茶始摘期及霜冻风险区划   总被引：1，自引：1，他引：0  

兰小建  汪晨  余丽萍 《中国农学通报》2017,33(14):95-99

为了解浙江省乌牛早春茶初始采摘期的时空分布特征和减少遭受春季霜冻的风险,应用1971—2014年浙江省71个常规站日资料和2005—2014年共2094个气象自动区域站小时观测资料,以乌牛早春茶发育热量为始摘期区划指标和乌牛早春茶各级冻害总灾损率为霜冻害区划指标,应用GIS技术,采用距离权重反比法(IDW,Inverse Distance Weighted),得到浙江省乌牛早春茶始摘期区划图和乌牛早春季霜冻风险区划分布图。结果表明:浙江全省乌牛早春茶始摘期在2月上旬—3月上旬,从南到北时间递增,温州沿海地区最早,29°N以南为2月中旬,30°N以北地区最晚。浙江沿海、盆地、低丘陵地区适宜种植乌牛早茶,海拔高的地区遭受春季霜冻风险大,不适宜种植乌牛早茶,区划结果将为茶叶主管部门和农技推广部门指导乌牛早种植的布局调整提供重要参考价值和科学依据。  相似文献   

Juvenility,maturation and rejuvenation in plants: adventitious bud formation as a novel rejuvenation process     

Ola M. Heide 《The Journal of Horticultural Science and Biotechnology》2019,94(1):2-11

  相似文献