小麦植株内糖类的昼夜变化

1.田间条件下灌浆期的小麦,叶子、叶鞘、及节间里的含糖量有着昼夜的变化,其中主要是蔗糖含量的变化。在日间下午3—6时含糖量最高,而晚上含糖量降低。2.小麦叶子、叶鞘及节间含糖量的变化受到环境因素的影响。这里主要是光线及植物社会的影响。3.在阴天只有单行植株第1叶和第2叶里的蔗糖有显著的昼夜变化;叶子、叶鞘变化很小,还维持了原来的水平。中行植株的叶子、叶鞘及节间的含糖量一般是降低的。4.在晴天,不问单行植株、中行植株,叶子、叶鞘和节间的含糖量都有昼夜的变化。但含糖量变化的进程在单行植株和中行植株之间有着很明显的差异。单行植株的含糖水/平高于中行植株。它们之间差异的幅度,越是在下部的器官越是显著。单行植株叶子、叶鞘的蔗糖最高含量在下午6时到达,而中行植株叶子、叶鞘里的蔗糖最高含量早在下午3时就达到了。这种差异的形成由于中行植株被左右边行的植株所荫蔽,在光线条件上处于不利的状态。在阴天中行植株的光线条件更差,以至阻碍了光合作用的进行。5.小麦在灌浆期,叶、叶鞘、节间糖的分布是这样的:叶子里的糖浓度小于叶鞘,叶鞘里的糖浓度小于节间的。但当阳光充足的时候,叶子里的浓度有时高于叶鞘中的浓度。此外第2节间的糖浓度高于第1节...     

OBSERVATIONS ON SYNAPTONEMAL COMPLEXES IN PREMEIOTIC INTERPHASE OF WHEAT

Synaptonemal complexes (SCs) were found in stage 3, premeiotic (S phase) pollen mother cell (PMC) nuclei of wheat which were labeled with ³H-thymidine. Three nucleoli are present in PMC nuclei at the beginning of stage 3, premeiotic interphase (S3). During S3, nucleoli move toward the nuclear envelope and fuse to form one nucleolus near the end of the stage. PMC nuclei labeled with ³H-thymidine were serially sectioned to show that more than one nucleolus was present and that SCs were also present in these DNA synthetic nuclei. Entire S3 PMC nuclei were serially sectioned to show the presence of SCs and all three nucleoli. Entire leptotene nuclei were also serially sectioned and segments of SCs were found. It is concluded that the association of homologous chromosomes in S3 of wheat is an early step in SC formation which proceeds through leptotene and is completed in zygotene and pachytene. Thus there is evidence that the continuum of chromosome pairing in wheat starts much earlier than was once thought.     

小麦离体花药中花粉核无丝分裂的电子显微镜观察

用电子显微镜观察到,在离体培养的小麦花药中,花粉细胞在脱分化分裂时,除了进行有丝分裂之外,还存在着两种类型的无丝分裂——劈裂(cleavage)和碎裂(fragmentation)。它们都是通过核膜的内陷实现的。认为劈裂式无丝分裂导致游离核花粉的形成,碎裂式无丝分裂导致微核花粉的形成,两者都可引起亚倍体和非整倍体植株的产生。     

麦双尾蚜发生数量与小麦播种期的关系

新疆伊犁和塔城冬、春麦田的麦双尾蚜Diuraphis noxia (Mordvilko) 有虫株率和百株蚜量,与小麦播种时间密切相关。在小麦正常播种期内,冬小麦晚播可以显著减少麦双尾蚜数量,每晚播种10天,第二年麦双尾蚜有虫株率可以下降40%～70%;春小麦每晚播种10天,麦双尾蚜有虫株率增加30%～88%。     

各种昆虫耐饥力的观察

昆虫耐饥力的强弱,为昆虫的生物学特性之一。对於这个问题,以前还没有人作过系统性的观察。1950—1951两年,我们在这方面,曾经化了一些时间,并已初步得出一些结果,现在把它整理出来,以供大家讨论。     

EFFECTS OF GIBBERELLIN ON GAMMA-IRRADIATED WHEAT

Haber , Alan H., and Helen J. Luippold . (Oak Ridge National Laboratory,² Oak Ridge, Tenn.) Effects of gibberellin on gamma-irradiated wheat. American Jour. Bot. 47(2): 140—144. Illus. 1960.–After receiving large doses of gamma rays, wheat grains can germinate and grow into small seedlings, either in water or in a solution of gibberellic acid, without undergoing any mitosis. Gibberellic acid stimulates growth of plants from grain given twice the dose that abolishes all detectable mitotic activity. Therefore, it must stimulate growth of these irradiated plants by cell expansion alone. Growth stimulation in shoots from such irradiated grain was reflected in increased dry matter content and other responses characteristic of gibberellin treatment. Comparison of the shoot height-dose curves for plants grown in water and those in gibberellin suggest that cell division per se does not contribute greatly to the gibberellin stimulation of growth in unirradiated young wheat seedlings. The effect of gibberellic acid on plants from grain irradiated sufficiently to prevent subsequent mitotic activity was on the total extent of growth, not only on the rate. The general ineffectiveness of gibberellin on mature tissues can not be attributed to the cells having reached the maximum size that they were potentially capable of attaining, but must be caused by a physiological incapacity of the cells to respond to gibberellin treatment. These results are discussed in connection with recent reports that stimulation of growth by gibberellin can be attributed solely to an increase in cell number.     

OBSERVATIONS ON THE CONTROL OF MITE INFESTATIONS IN STORED WHEAT BY CHEYLETUS SPP. (ACARINA, CHEYLETIDAE)

An account is given of the control of the grain mite Acarus siro L. (= Tyroglyphus farinae L.) by the predatory mite Cheyletus sp. in imported wheat stored in bags or in bulk. After 12–18 months of storage Cheyletus sp. had developed in 75% of the parcels of wheat and in 67% of these it became dominant over other mites. This usually occurred in late summer for bagged wheat. Control of A. siro by Cheyletus sp. compared favourably with that achieved by fumigation with methyl bromide and on occasion was superior. Both development and dominance of Cheyletus sp. were adversely affected by earlier fumigation but there was some evidence that spraying wheat with γ-BHC favoured the development of this species and, in some circumstances, its dominance. Dominance by Cheyletus sp. in bulk grain often occurred in the winter months when the surface moisture content of the wheat was at its highest.
The development of Cheyletus eruditus Schr. is described in a bulk grain store where dense populations of A. siro and Glycyphagus destructor Schr. were eliminated by the predator. The numbers of C. eruditus in wheat tended to increase faster when the surface layers were disturbed than when the grain was undisturbed. Nevertheless, dominance over the other mites tended to occur first in undisturbed grain.     

江豚鳍肢骨骼形态特征的观察

江豚Neophocaena phocaenoides鳍肢的基本结构与海洋豚类相同,但又有其特殊性。为完善江豚鳍肢骨骼形态特征的研究,本文通过运用原位解剖、制作透明鳍肢骨骼以及X光拍照的方法,对威海海域四头江豚的鳍肢骨骼进行了较全面、较系统地观察和测量,对每一块骨骼的名称、位置、形状、大小做了详细描述,并分析了没有中央腕骨和腕骨1的原因,这些在以往的研究中还未见报道。标本具有不同的年龄和性别,采集的时间和地点也不同,因此,本结果带有一定的普遍性。与以往研究鳍肢骨骼的方法相比,制作透明鳍肢骨骼具有直观、完整、清晰、美观、准确、易于观察等特点,辅以X光照片观察得出与以往研究的结果有很大差别,如国内外学者原来记述腕骨的形态为5块相连成一平坦的椭圆形盘状;指式总结为:Ⅰ2-3,Ⅱ5-9,Ⅲ5-8,Ⅳ3-4,Ⅴ2-3。而作者记述为在整体上,腕骨与包围它们自身的软骨共同连成一平坦的不规则多角形;指式为:Ⅰ0-1,Ⅱ6,Ⅲ5,Ⅳ2,Ⅴ0(掌骨不计)。据分析,造成这些差异的主要原因之一是研究方法的不同。       

麦蚜在不同抗级小麦上刺吸行为的比较

应用EPG(E1ectrical Penetration Graph)技术记录了麦长管蚜Sitobion avenae F.及禾谷缢管蚜Rhopalosiphum padi L.在不同抗性级别的小麦品种(红芒红、小白冬麦、kok1679和L₁)上的取食行为。结果表明,麦蚜在参试品种上刺吸的各种特征波型基本相同,但其出现时间、重复出现的次数及历期长短存在差异,其中自开始记录至第一次出现E₁：波的时间及E₂。波历期比率可做为参试品种是否抗蚜的主要生理性指标。依据主要波型统计参数用聚类分析方法对参试品种抗蚜性进行分类,其结果与室内生命表参数研究及田间鉴定结果基本一致。本文还对EPG在抗性因子定位、抗蚜鉴定中作用及EPG记录的影响因素略作讨论。