Factors affecting potassium fixation in seven soils under 15-year long-term fertilization

Potassium （K） fixation by seven soils, including black soil, fluvo-aquic soil, grey desert soil, loess soil, paddy soil, red soil and purple soil, was determined by laboratory simulation under a fifteen-year-period of long-term fertilization. Factors affecting soil K fixation were then discussed by factor analysis and stepwise regression. Magnitude of soil K fixation rate was as follows： the black soil 〉 the purple soil 〉 the loess soil 〉 the fluvo-aquic soil 〉 the paddy soil 〉 the grey desert soil 〉 the red soil. Our results showed that soil K fixation capacity was significantly affected by the clay mineral types in the soils. Potassium fixation capacity of soils, whose 2：1 layer silicates were dominant minerals, was affected by two components extracted by the method of principal component analysis： the first including soil available K, slow available K and K^＋ saturation, and the second including cation exchange capacity （CEC）, soil organic matter （SOM） and 〈0.002 mm clay contents. Potassium fixation rate was mainly affected by K^＋ saturation and CEC with lower added K concentration （from 0.4 to 1.6 g/L）, and by K^＋ saturation and 〈0.002 mm clay content with higher added K concentration （from 2.4 to 4.0 g/L）.     

Roles of MAP kinase signaling pathway in oocyte meiosis

Mitogen-activated protein kinase (MAPK) is a family of Ser/Thr protein kinases expressed widely in eukaryotic cells. MAPK is activated by a cascade of protein kinase phosphorylation and plays pivotal roles in regulating meiosis process in oocytes. As an important physical substrate of MAPK, p90^rsk mediates numerous MAPK functions. MAPK was activated at G2/M transition during meiosis. Its activity reached the peak at MⅠ stage and maintained at this level until the time before the pronuclear formation after fertilization. There is complex interplay between MAPK and MPF in the meiosis regulation. Furthermore, other intracellular signal transducers, such as cAMP, protein kinase C and protein phosphotase, ect., also regulated the activity of MAPK at different stages during meiosis in oocytes. In the present article, the roles of MAPK signaling pathway in oocyte meiosis are reviewed and discussed.     

不同施肥和施药水平对稻虱多索线虫的影响

报道了稻虱多索线虫的发生与稻田的不同施肥和施药水平的关系,并对稻虱多索线虫的发生与寄主的关系进行了较详细的探讨,发现稻虱多索线虫对稻飞虱不同种类及同一种类不同龄期的寄生具有选择作用,同时为保护和有效利用稻虱多索线虫提出了相应对策.     

小麦异源2号、中国春与球茎大麦远缘杂交的受精和早期胚胎发育

用石蜡切片法，对普通小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）异源２ 号、中国春与球茎大麦（Ｈｏｒｄｅｕｍ ｂｕｌｂｏｓｕｍ Ｌ．）远缘杂交受精过程和早期胚胎发育进行了比较观察．实验表明，仅具１对Ｋｒ基因的异源２ 号和具３ 对Ｋｒ基因的中国春与球茎大麦杂交，其受精和胚胎发育存在着明显的差异．为小麦与球茎大麦远缘杂交提供了细胞胚胎学证据．     

不同种公牛精液对牛卵母细胞体外受精效果影响的研究

分别利用不同个体的海伏特、安格斯和荷斯坦种公牛精液进行体外受精，观察了不同品种不同个体种公牛精液的体外受精效果，利用五种海伏特种公牛精液进行体外受精后卵裂率为１７．６％～７４．７％，囊胚发育率为１．０％～３２．６％，不同个体间差异极显（Ｐ〈０．０１）。利用五种安格斯种公牛精液进行体外受精后卵裂率为３４．７％～８５．３％，囊胚发育率为６．２～４０．５％，不同个体间具极显差异（Ｐ〈０．０１）。利用     

亚铵黑液作肥料施于麦田对水环境的影响

为掌握亚铵黑液作肥料施于旱地对浅层地下水的影响．以麦田为研究对象．给出了旱地不同施肥方式黑液对浅层地下水的环境影响结果．     

不同配方施肥对油茶生长发育及其生理特性的影响

施肥是促进植物生长的一种重要措施之一。该试验通过N、P、K三种不同肥料类型、不同配方对三年生油茶幼林进行正交施肥,共9个处理和一个对照,并采用多重比较法,分析了不同处理对油茶生长发育和生理特性的影响。结果表明：不同的配方施肥对油茶的生长发育有一定的促进作用。在9个处理中,分别以Ⅴ、Ⅸ、Ⅲ、Ⅱ4个处理对油茶的地径、树高、冠幅和新梢影响最大。在Ⅵ、Ⅷ处理时,油茶叶片的叶绿素含量和硝酸还原酶活性均存在最大差异。     

施肥对绿洲区苜蓿与无芒雀麦混播草地生产性能的影响

特定施肥水平（N225kg／hm^2、P150kg／hm^2）T,对建植第3年不同比例（5：5、6：4、7：3）混播草地中苜蓿和无芒雀麦的株高、产草量、茎叶比及产草量变异系数进行了研究,结果表明：施肥对7：3混播草地中苜蓿和无芒雀麦株高、产草量促进作用最大。各比例混播草地年产草量施肥组和对照组差异极显著（P〈0．01）。7：3混播草地中,苜蓿和无芒雀麦的茎叶比施肥组均低于对照组,但5：5和6：4混播草地中,施肥组和对照组茎叶比无明显规律。7：3施肥组产草量变异系数最小。7：3建植的混播草地施肥组表现出较高的生产性能,可以获得优质高产的饲草。     

斑马鱼雌核紫外线辐射灭活及延迟受精的研究

雌核灭活是雄核发育的第一个关键步骤,为研究紫外线对斑马鱼卵的雌核灭活效果,将斑马鱼的卵采用干法或置于纯水、Ringer氏溶液和Cortland鱼用生理盐水进行紫外线照射,结果表明,各种方法中均得到畸形鱼苗,并经染色体检查大多为单倍体;四种方法中在Cortland鱼用生理盐水中灭活效果最好,120 mJ·cm-2紫外线可以使雌核完全灭活;干法处理不能达到雌核完全灭活的目的,在纯水中灭活后的卵子受精率较低.而延迟受精的结果也表明,盐度较高的Cortland鱼用生理盐水可以较好的保护卵子,维持较长时间的受精能力,和其它处理方法有明显的差异.