摘要:

Nel ciclo dello sviluppo dell'archegonio diPinus pineasi possono schematicamente distinguere tre periodi per quanto riguarda lo stato della membrana che circonda la cellula centrale.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796114

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796115

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

A developmental study of ovule formation inDendrobiumXJ. Thomas is reported. The ovulary at anthesis is rudimentary and consists of only a placental ridge. Upon pollination the placental ridge undergoes proliferation and ultimately produces embryo sacs. Normally the ovulary requires 6½ to 7 months from the time of pollination to mature. Of the total time, 35–40 days or 1/6 of the period is required for cellular proliferation on the placental ridge and another 1/6 for the formation of embryo sacs. The early developmental stages within the ovulary are subdivided into phases —quiescent, proliferative, nucellar, archesporialandmeiotic.Relative volume changes which occur within the developing cell (nucleo-cytoplasmic ratio) and within the developing ovule during the established phases are also presented.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796116

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

L'Autore ha esaminato eariologicamente parecchi lotti di piante di Scilla autumnalis (Liliaceae) raccolti nei pressi di Gerusalemme e di Tel-Aviv. Tali piante risultarono regolarmente diploidi (2n= 14) ad eccezione di una sola pianta (proveniente da Gerusalemme) che si rivelò provvista del corredo regolare più 6–8 B-cromosomi, eucromatici, con centromero subterminale, e quindi con cariotipo 2n= 14 + 6–8 B.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796117

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

Comparison of yield performance of the dwarf orange and green coconuts of the West coast of India, their off-type progenies, tail ‘female’ × dwarf ‘male’ hybrids and West Coast Talls grown in the Central Coconut Research Station, Kasaragod showed that the off-type progenies of the orange dwarf are very economic yielders. Though they have been considered by earlier workers to be products of out-cross of the dwarfs with tall ‘males’, controlled crosses conducted in this Station show that ca. 50% of the progenies of dwarf orange ‘female’ × tall ‘male’ and ca. 75% of those of dwarf green ‘female’ × tall ‘male’ crosses turn out to be of the purely dwarfish type. Irrespective of the colour characters of the tall pollen parents used, the off-type progenies of the orange dwarfs showed reddish petiole colour; those of the green dwarf were mostly green. Under controlled selfing of the orange dwarf, seedlings resembling the natural off-type progenies were obtained in the same frequency as under open pollination. They, however, revealed slight inbreeding depression. The results of selfing suggest that dwarf coconuts are not homozygous to the extent now conceived and that the off-type progenies of dwarfs might be heterozygous segregates, perhaps with imposed hybridity. The appearance of pure dwarfs in dwarf × tall crosses in more or less the same proportion as in natural progenies of dwarfs is intriguing and inexplicable and an answer to this can possibly be had only by a better understanding of the genetics of the character of dwarfness in coconuts.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796118

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

Talee radicate delle varietà di garofano « Cardinal Sim » ed « Elia rosso », ambedue a fiore semidoppio, furono irradiate con 7.500 e 10.000 r di raggi gamma da60Co. In R1, in aggiunta a modificazioni fisiologiche, si osservarono vari tipi di mutazione, che si propagarono in vR2e vR3. Furono osservate mutazioni per i seguenti caratteri:1)Colore del fiore.In « Cardinal Sim » fu osservata una sola pianta con la mutazione « bianco »; in « Elia » si osservarono mutazioni « Opale rosa », » Pesca », bianco con stria rossa centrale nel petalo e rosso variegato di bianco. La massima parte delle mutazioni apparvero in una condizione chimerica nelle branche.2)Numero dei petali.Oltre a fiori semplici (5 petali e antere di aspetto normale) in tre piante R1, si ottennero numerosi casi con un numero di petali minore del controllo in ambedue le varietà; in « Cardinal Sim » si ebbero anche poche piante mostranti fiori con un aumentato numero di petali (numeri alti e numeri bassi di petali poterono essere mantenuti per propagazione vegetativa). Questi dati suggeriscono che il carattere « numero di petali » nel nostro materiale sia controllato da un sistema poligenico. In « Elia », fiori con un ridotto numero di petali (media 17 ca. invece del 34 ca. del controllo), erano spesso caratterizzati da un calice lungo e stretto. Non si sa se si tratta di un effetto pleiotropico o di una seconda mutazione contemporaneamente occorsa.3)Deficienze clorofilliane.Settori a deficienze clorofilliane (giallo soffuso di verde, albino) osservate in R1dettero per propagazione vegetativa piante interamente mutate incapaci di sopravvivere.4)Cerosità.Furono osservati settori con assenza di cera (« waxless »).

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796119

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

1.A cytotaxonomic study of the family. Apocynaceae representing 24 genera and comprising of 48 species and varieties has been made. Thirty of these plants representing 11 genera have been karyologically investigated for the first time. In the remaining 18 plants where some cytological informations were available, karyotypic analyses of the mitotic chromosomes have been reported for the first time in 5 and meiotic study in 2 of them. Up-to-date informations available in 87 species and varieties from the works of different authors have been tabulated.2.The chromosome numbers in different genera of this family reported earlier and observed during the present investigation has revealed the presence of the following basic numbers: 8, 9, 10, 11, 12, 16 (8), 18 (9) and 23. About 76 per cent of the plants have the basic chromosome numbers of ten and eleven; 11.9 per cent show nine or multiple thereof; 5.9 per cent show twenty-three; 3.0 per cent show eight or multiple thereof and 3.0 per cent show twelve as their basic chromosome numbers.3.The subfamily Plumieroideae comprises genera with a wide variation in chromosome numbers which range from 2n = 16 to 2n = 92. In the other sub family Echitoideae most of the plants have 2n= 20 and 22 chromosomes, and a couple of them 2n= 24.4.New polyploid series have been detected in 3 out of the 24 genera studied, where 3 series were reported earlier. The frequency of polyploid species and varieties is about 12.5 per cent in Apocynaceae, estimated from 48 species and varieties of this project and 10.5 per cent when all the previous reports were taken into consideration. All the polyploid species and varieties are confined to the subfamily Plumieroideae.5.The chromosomes are small ranging from 0.7 μ, to 4.8 μ in length and the plants of the subfamily Echitoideae have, in general, smaller chromosomes having none longer than 3.4 μ.6.The chromosomes have mostly median to submedian and in a few cases subterminal primary constrictions. Considerable variation exists in the karyotype within varieties and between species. Chromosomes with secondary constrictions could be detected in most of the plants varying from 2 to 8 in number.7.On the basis of this cytotaxonomic study, it is evident that the plants of the two subfamilies — Plumieroideae and Echitoideae of SCHUMANN are natural groups conspicuously differing in several characters. The following conclusions have been drawn: The genusAllamandais quite distinct for its fewer and larger chromosomes.Vinca roseaL. on the basis of its morphological and cytological characteristics should be transferred fromVincaLinn, toLochneraReich, and calledLochnera rosea(L.) Reich. The subtribe Alstoniinae is a heterogeneous group as it has plants with different habits and chromosome numbers. It is desirable to separateLochnera, VincaandAmsoniainto a new subtribe. The status ofPlumeriain this subtribe needs a thorough reinvestigation. The position of the genusThevetiawith 2n= 20 chromosomes, syncarpous pistil and funnel-shaped corolla in the subtribe Cerberineae is ambiguous. The tribe Echitideae may be conveniently divided into the two sub-tribes — all the woody climbers in one and the plants with shrubby habits viz.StrophanthusandNeriumin another. It also seems reasonable to transfer the genusVallarisfrom the tribe Parsonsieae to the tribe Echitideae and be placed in the new subtribe with the woody climbers.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796120

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

Viene esaminata l'infrastruttura dei plastidi presenti nel tessuto corticale del fusto delle plantule diCuscuta australisappena germinate (di colore giallastro) ed a circa sei giorni dalla germinazione (di colore verde-pallido).

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796121

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

1.Diploid species ofDichanthiumare genetically isolated from each other.2.Diploid races of the more commonly tetraploid speciesD. aristatum, D. annulatumandD. caricosumcould be crossed with tetraploidD. annulatum.3.Hybrids were also produced between the strictly diploid speciesD. panchganienseand tetraploidD. annulatum.4.Chromosome homology appeared to be absent between the basic genomes ofD. annulatumandD. panchganiense, while some degree of homology seemed to exist between the genomes of tetraploidD. annulatumand the diploid races ofD. aristatumandD. caricosum.5.Morphological data indicated that the Indian diploid speciesD. panchganienseandD. maccanniiare closely related. Similarly the Australian diploidsD. humilius, D. sericeum, D. setosumandD. superciliatumform a morphologically related group.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796122

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor

摘要:

Proseguendo le ricerche sull'ibridazione fraTriturus helveticuseT. vulgarisabbiamo ottenuto una seconda generazione reincrociando alcune femmineT. helveticus/vulgariscon maschi T.vulgaris meridionalis; soprattutto la ♂F1-n. 4 è risultata feconda in tre annate successive ed ha deposto numerose uova che si sono sviluppate. La grande maggioranza degli embrioni e delle larve nati da questa femmina ha presentato però una serie di anomalie, quali asciti, microcefalia, ipomorfosi branchiale, mancanza di uno o di entrambi i bilanceri, circolazione difettosa o arresto totale del circolo sanguigno, edema. Tali anomalie sono in tutto simili a quelle che caratterizzano la cosiddetta « sindrome iperdiploide », la quale è confermata anche da reperti cito-istologici. Malgrado la forte mortalità embrionale conseguente a tali anomalie, si sono ottenuti alcuni R1adulti di ambo i sessi, di cui vengono descritte le caratteristiche fenotipiche salienti.

ISSN:0008-7114    

DOI:10.1080/00087114.1964.10796123

出版商:Taylor & Francis    

年代:1964

数据来源: Taylor