羊草和大针茅群落的暗呼吸强度与环境条件关系的初步探讨

草原群落的干物质产量,是由光合作用和呼吸作用所决定。呼吸作用对于干物质的生产是必不可少的一环,因为任何物质的形成都需要能量,而这种能量正是由呼吸作用所提供的。#br#草原群落的生长、呼吸和光合受到光照、温度、水分和土肥等环境因子的影响。在适宜的气候条件下,生长、呼吸和光合有着严格的偶联关系,并能使群落的生长效率保持比较高的水平,然而在异常的气候条件下,如高温、干旱、低湿等,会增加群落的无效呼吸,使光合产物过量的消耗,导致偶联关系的破坏,光合效率下降,终致造成植物的死亡。#br#本文就羊草和大针茅草原群落的暗呼吸强度与环境条件的关系进行探讨,视其对草原群落光合生产效率的影响,从而为人工促进天然草原生产力的提高,提供依据。     

灌水施肥对羊草(Aneurolepidium chinense)草原群落光合速率的影响

对天然羊草群落进行灌水和施肥后,测定了它们(灌水、灌水加施肥和对照)的群落光合速率。结果如下:1.在灌水、施肥加灌水处理后23天测定,处理群落的叶层高度分别比对照高8%和9%;群落LAI分别比对照高68.97%和99.93%;群落生物量分别比对照高41%和65.69%;群落日净光合量分别是对照的2.48倍和3.76倍;最大光合量分别是对照的2.82倍和3.12倍。2.灌水施肥处理后,羊草群落光合速率日变化的类型与对照基本一致,属于双峰型。唯独灌水加施肥群落(处理后3天)是单峰型,没有中午降低现象。看出较好的水肥条件能改变群落的日变化类型。3.在温湿度条件较差时或随着处理时间的推移,处理的效果越显著。第一阶段测定时,灌水、灌水加施肥处理的群落日净光合量分别是对照的1.26和1.17倍。第二阶段测定时,分别是对照的1.40和1.84倍。第三阶段测定时,分别是对照的2.48和3.76倍。     

Relationship Between Ethylene Release,Membrane Permeability and Activity of Polyphenol Oxidase Changes of Duck (Pears Pyrus bretschnideri Rehder) During Low Temperature Storage

Duck pear (Pyrus bretschneideri Rehder) tends to develop browning core after 55 to 60 days storage at low temperature (0℃). Following physiological changes of the duck pear during storage at different temperature were investigated: (1) As compared with 20℃, ethylene release is obviously decreased and its peak is retarded for 15 days at 0℃. Levels of internal ethylene are variant at different individuals harvested at same time. Concentrations of internal ethylene are in accord with ethylene release. The higher internal ethylene is, the easier the pear core becomes brown. (2) At 0℃, activity of polyphenol oxidase in the core increases with ethylene release enhancement. After ethylene peak passes, its activity is lower than before. (3) The electric conductivity of cores is higher at 0℃ than at 20℃. During post climacteric period, the electric conductivity increases irreversibly, then browning core occurs. From above results, it is concluded that interactions between two factors induce the browrang core of the duck pears at low temperature. One is chilling injury caused by low temperature, another is ethylene function. They stimulate the activity of polyphenol oxidase and enhance the membrane permeability.     

叶表皮细胞结构在国产狗尾草属(Setaria Beauv.)分组水平上的应用

本文对狗尾草属国产15种进行叶表皮细胞结构的显微观察,作为狗尾草属内分组特征之一。研究结果是:1.进一步证实叶表皮脉间细胞的形态是禾本科属下分类的好特征,2.国产种类叶表皮细胞形态为六个类群,基本上符合外部形态所分成的六个组,其中个别种类出现的分化现象,也正好说明其彼此的演化关系。     

中国盾脸姬蜂亚科一新种及一新记录(膜翅目：姬蜂科)

中国盾脸姬蜂亚科一新种及一新记录（膜翅目：姬蜂科）盛茂领章英（林业部森林病虫害防治总站沈阳１１００３４）１９９５－０４－２０收稿,１９９６－０１－１７收修改稿·９２·黄脸姬蜂属ＣｈｏｒｉｎａｅｕｓＨｏｌｍｇｒｅｎ,１８５６和突唇姬蜂属Ｉｓｃｈｙｒｏｃ...     

The Physiological Effects of Ethrel on Seedlings of Second Season Rice

Spray of ethrel (1000 ppm)to seedlings of double-cropping second season rice at 5-leaf stage can control plant height and root length, and consequently makes seedlings strong and tough. The ABA content and ethylene released by young seedling were significantly higher than the control. However, there were some changes: cell elongation inhibited, leaf area decreased, and leaf color became dark green, photosynthetic rate increased, translocation of photosynthetate in leaf sheath enhanced, leaf emergence was rapid. The growth of root system and root vigor were though temporarily inhibited, but slightly increased after transplantation. All these are beneficial to seedling quality, the plant growth and development after transplantation, which subsequently bring about positive effects on stimulating early heading and on increasing rice yield.     

Approach to Physiological Functions of Ethrel in the Ripening of Cotton Boll

Both leaf and boll of cotton can absorb ethrel and the acceptor releases ethylene rapidly. Ethrel absorbed by leaves can release ethylene in bolls, whereas that absorbed by bolls cannot release ethylene in leaves. Bolls treated with ethrel has two peaks in ethylene releasing. The first peak appears about two days after treatment, and the second appears before the splitting of boll. The control has only one peak in ethylene releasing which appears eight days later than the second peak of the bolls treated with ethrel. This coincides with the fact that ethrel enables bolls to split seven to ten days earlier. The releasing of ethylene by cotton bolls is closely related to temperature, and is accelerated with increasing temperature no matter cotton bolls are treated with ethrel or not.     

链格孢菌原生质体的制备与限制性内切酶介导整合(REMI)转化的致病性诱变

以链格孢菌Alternariaalternata菌株NEW为供试菌株,研究了菌龄、酶系统、酶解时间、酶解温度及稳渗剂对链格孢菌原生质体制备的影响。结果表明,制备链格孢菌原生质体比较适宜的条件为PD液体培养基培养20h,以0.7mol/LNaCl为稳渗剂、1%LysingEnzyme、1%Drislase和1%Snailase3种酶溶液混合使用,30℃酶解3h。对原生质体进行了限制性内切酶介导整合(REMI)转化,筛选到了链格孢菌弱致病突变株NEW001,为致病相关基因的标记和克隆打下了基础。     

补体攻膜复合体致肾小球脏层上皮细胞粘附性改变研究

为探讨膜性肾病中补体攻膜复合体(MAC)介导蛋白尿机制,本研究制作了MAC致肾小球脏层上皮细胞(GVEC)亚溶破模型。通过对细胞局部粘附及相关蛋白的观察发现,MAC亚溶破致伤GVEC后,其粘附性发生改变。其机理与ECM分泌失调、膜硫酸化物质及整合素减少、细胞骨架重排有关。这些改变导致体内GVEC脱附,足突退缩融合,从而参与膜性肾病的蛋白尿产生。