木兰科植物的嫁接繁殖

本文对38种木兰科植物的嫁接繁殖进行了试验,全部嫁接成功,平均成活率为44．0％。不同属的木兰科植物之间有较大的亲和力,多数种可进行属间嫁接。嫁接时间和砧木选择是影响木兰科植物嫁接成活率的主要因素,嫁接方法对成活率也有一定的影响。木兰科植物的嫁接苗比实生苗具有更强的适应性和速生性。     

漳州水仙在武汉水培开花规律试验初报

通过试验表明,漳州水仙在武汉水培时:(一)在本试验期内的自然气温下,40桩规格的商品鳞茎从水培至始花,最多需时83天,最少47天。水培开始早的需时较长,开始晚的需时较短。(二)开花期的长短,与花期内气温平均值明显相关。平均值升高,花期缩短。(三)在本试验所述的条件下,供春节观赏的水仙,应在节前60—70天开始水培。过早,始花期延长,管理费事。过迟,不能适时开花,而且花期将因气温升高而缩短。(四)40桩规格的商品鳞茎,每个平均有花3.2葶,24.8朵。质量较好,而价格较低,适合子一般群众消费。     

罗汉果嫁接繁殖研究

采用1—3年生青皮砧木,用镶枝接、嵌合接、劈接和腹接法嫁接,成活率为67.86～81.82％,以镶枝接最好。用长滩、拉江和青皮接穗嫁接,成活率为60—80％,以拉江接穗最好。嫁接苗早期结果,接后90天80—88％的植株结果并保持原品种优良类型。     

几种楝科植物种核油对褐稻虱的拒食作用试验

某些楝科种核油对褐稻虱具有特殊的作用,它与常规的化学杀虫剂不同,并不直接杀死害虫,而是引起褐稻虱对使用种核油的水稻产生拒食或避忌,对褐稻虱重要天敌蜘蛛类并不伤害。     

试管苗嫩枝顶端嫁接技术的研究

根据植物顶端生长优势的原理,在猕猴桃(Actinidia chinensis)胚乳培养中,将愈伤组织上分化的芽,切割下来作接穗,利用简单装置,进行“嫩枝顶端嫁接”,嫁接成活率高达90%左右,并至少提前1—2年开花、结果。利用嫩枝顶端嫁接技术,不仅提高了试管苗的成活率,而且在简化培养程序、缩短培养周期、降低培养成本上都有明显的效果。     

THE STRUCTURE OF GRANA IN FLOWERING PLANTS

A model of granum structure, consisting of multiple helical frets wound around each cylindrical granum, is proposed as a representation of granum structure for flowering plants in general. This model was originally formulated for grana in the mesophyll plastids of Zea mays and was subsequently extended to grana of Phaseolus vulgaris by additional studies. The model is now shown to be applicable also to grana in the plastids of Cannabis sativa, Elodea canadensis, Nicotiana rustica, Pisum sativum, and Spinacia oleracea. This sample of seven angiosperms includes genera commonly studied by other workers in their ultrastructural investigations of plastid structure.     

大豆开花后光周期反应的研究

利用中国大豆主要生态区的生育期不同的代表品种研究了大豆（Ｇｌｙｃｉｎｅ ｍ ａｘ （Ｌ．）Ｍｅｒｒ．）开花后对光照长度的反应． 结果表明,不同成熟期的大豆品种开花后普遍存在着对光照长度的反应．这种反应属于典型的光周期现象,而不是由温度的替代作用、光合时间的改变或前期短日后效应引起的．开花后光周期反应不仅存在于大豆的花荚期,而且存在于鼓粒期．研究认为∶大豆开花结实对光周期的需求是一个连续过程;光周期对大豆生育期的调控作用存在于出苗至成熟的全过程;光周期诱导开花和促进成熟的作用有一定的共同性;光周期诱导效果具有持效性和可逆性     

银杏嫁接试验

本文报道银杏(Ginhgo biloba Z)小苗(一、二年生)嫁接试验结果。单芽切接、腹切接不仅成活率高且操作简便、工效高,是小苗嫁接值得推广的嫁接方法;嫁接时期应以秋接为主、春接为辅,秋季嫁接时闯长达二个半月,成活率高而稳定、生长期较长;砧木和接穗的年龄对成活率无大影响,建议用多年生(3—5年)接穗嫁接,以利提早结实;一年生双砧嫁接,是快速育苗的重要手段之一。     

THE REGULATION OF ALTERNATION OF GENERATION IN FLOWERING PLANTS

The developmental changes involved in the alternation of generation represent the major gene-switching events in the life history of plants. While a large number of genes are common to both sporophyte and gametophyte, many thousand sequences are specifically expressed in each generation; indeed, certain key constituents (e.g. tubulin) are encoded by different genes in each generation, indicating that sporophyte and gametophyte are responding to different evolutionary pressures. Evidence is accumulating that major gene-switching events in plants, such as flowering, are regulated by complex control systems which ensures that development occurs only in the correct groups of cells at the appropriate time. A similar, or more sophisticated system might thus be expected to regulate alternation of generation. It is not possible to manipulate alternation of generation in a similar fashion to flowering, but study of apparent aberrations of development occurring in nature and in vitro suggests that alternation only occurs in cells which have become competent to receive particular developmental stimuli. Further, in certain cases, competent cells may be switched either into sporophytic or gametophytic developmental pathways depending upon the nature of the stimulus. Acquisition of competence seems to involve isolation of cells from the symplast, some cytoplasmic dedifferentiation, and perhaps cell cycle arrest or transition. The stimuli in vivo appear metabolic in nature, although embryogenesis may be activated by specific classes of glycoproteins. Interestingly, examination of agamospermic systems suggests that fertilization of the egg per se is not the signal which activates sporophytic development. Once competent cells have received the stimulus they start to develop, with no delay in a ‘determined’ state. Sporophytic and gametophytic development in vivo and in vitro both start with an asymmetric division, except for the female gametophyte which may arise via a range of developmental pathways, depending on the species.     

EXPERIMENTS ON THE COLONIZATION OF POTATO PLANTS BY APTEROUS AND BY ALATE APHIDS IN RELATION TO THE SPREAD OF VIRUS DISEASES

Batches of potato plants in pots were placed in the field for limited periods among plants infected with potato virus Y and leaf roll virus. Some of the potted plants were surrounded by sticky boards which prevented apterous aphids from reaching them. Almost as many plants within the boards as without became infected, indicating that most of the spread of virus was by winged aphids.
Apterae were probably responsible for spreading the viruses throughout a hill after one or more stems were infected. They may carry infection to neighbouring plants, but most of these will have been infected already by alatae.
The number of plants contracting infection was unaffected by watering.