scholarly journals Morphological Studies on the Regularity of Shoot Development in Rice Plants. VI. The regular relationship between leaf primordia developments in the main shoot and primary tiller buds.

1996 ◽  
Vol 65 (4) ◽  
pp. 618-625 ◽  
Author(s):  
Katsuya MATSUBA
Keyword(s):  
Shoot Development ◽  
Leaf Primordia ◽  
Main Shoot ◽  
Rice Plants ◽  
Morphological Studies ◽  
Primary Tiller

scholarly journals Growth and development of shoot apex in barley I. Morphology and histology of shoot apex in vegetative phase

2014 ◽  
Vol 49 (1-2) ◽  
pp. 21-31
Author(s):  
Zygmunt Hejnowicz ◽  
Wiesław Włoch
Keyword(s):  
Shoot Apex ◽  
Growth And Development ◽  
Apical Part ◽  
Leaf Primordia ◽  
Main Shoot ◽  
Vegetative Phase ◽  
Tunica Layer ◽  
Bulge Formation

The vegetative phase of development of the main shoot apex lasts over 5 plastochrons after germination. The endosperm has a sufficient store of nutrition for this period. At the beginning of this phase the apex has a one-layer tunica. The cells of the latter divide above the level of bulge formation for leaf primordia, exclusively anticlinally, although somewhat lower within the leaf bulge periclinal divisions may occur. The cells immediately under the first tunica layer in the apical part grow tangentially to the surface. These cells divide only anticlinally forming gradually the second tunica layer. In the course of the entire phase the shape of the meristeanatic caulis from the tip to the 4th frustum remains unchanged.

Phenological variation among Israeli populations of Cicer judaicum Boiss.

2005 ◽  
Vol 56 (11) ◽  
pp. 1219 ◽  
Author(s):  
Roi Ben-David ◽  
Shahal Abbo
Keyword(s):  
Flowering Time ◽  
Variance Components ◽  
Differential Response ◽  
Shoot Development ◽  
Population Variance ◽  
Main Shoot

To obtain knowledge about the phenological adaptation of wild Cicer, we studied Israeli populations of Cicer judaicum and quantified the flowering time and morphological vernalisation response. Vernalisation treatment led to a similar advance in flowering time in Israeli C. judaicum and in Turkish C. reticulatum. The two wild taxa, however, showed differential response in main shoot development following the vernalisation treatment. Between- and within-population variance components of the measured traits were estimated. Phenological variation between populations exceeded the variation between accessions within populations. We suggest that increasing the number of sampling sites at the expense of more intensive collection within sites is likely to optimise collection strategy for this species.

scholarly journals Experimental investigations of the shoot apex of Dryopteris aristata Druce

1947 ◽  
Vol 232 (589) ◽  
pp. 343-384 ◽  
Keyword(s):  
Shoot Apex ◽  
Apical Meristem ◽  
Vascular Tissue ◽  
Normal Development ◽  
Vascular System ◽  
Leaf Primordia ◽  
Terminal Region ◽  
Main Shoot ◽  
Marked Contrast ◽  
Medullary Parenchyma

A method whereby the apical meristem of the fern Dryopteris aristata Druce can be partially isolated from the adjacent lateral organs and tissues is described. This procedure has been adopted as a means of investigating growth and morphogenesis at the shoot apex. The technique involves the severance of the incipient vascular tissue which originates immediately below the apical meristem; the isolated meristem is thus seated on a plug of growing medullary parenchyma. Leaf primordia can be similarly isolated. Meristems treated in this way are capable of growth. They develop into short vasculated shoots bearing leaves. The nutrients sustaining this growth must reach the apical meristem from below by diffusing through medullary parenchyma at the base of the isolated terminal region. Above the parenchymatous region a solenostelic vascular system is present in the new axis; this is in marked contrast to the dictyostelic configuration of the parental shoot below. On the further growth of the isolated meristem leaves are produced and the stele becomes dictyostelic. The new leaves, of which as many as fourteen have been observed after 11 weeks’ growth, show the normal phyllotactic arrangement, and this is continuous with that of the main shoot below. The procedure adopted has the effect of removing the physiological dominance of the apical meristem relative to the main shoot; thus numerous large buds develop on the lateral segments of the parental shoot but none on the isolated terminal region. The growth of isolated leaf primordia is very limited. The vascular system develops as a solenostele, foliar gaps are not formed in the region of confluence with the shoot stele, axillary buds are developed, and the leaf apex becomes directed outwards. These several features are in marked contrast to the normal development. The isolated lateral segments are also capable of further growth. The experimental procedure adopted involves the severance of the vascular tissues at various levels. An account is given of new and hitherto unrecorded morphological developments observed in these segments. Interesting features include the formation of large solenostelic buds, the solenostelic development of isolated meristeles, medullation of meristeles and the induction of a polycyclic stelar condition, in one instance by a process of cambium-like activity. These are all in marked contrast to the normal development of the intact shoot. The data which have been obtained are discussed with special reference to the path of translocation of nutrients to the terminal meristem and to leaf primordia, morphogenetic processes at the shoot apex, the factors influencing the differentiation of the vascular system, and theories of shoot formation and constitution. The results of these experiments give no support to phytonic theories but emphasize the difference in potentiality for development between shoot and leaf primordia. In this connexion the factors which determine the shape and system of segmentation of the apical initials of shoot and leaf are seen to require further investigation. The hypotheses that lateral buds are inhibited by substances proceeding from the apical meristem, that the initial differentiation of vascular tissue can be attributed to the basipetal diffusion of a substance or substances from the actively growing apical meristem, and that under conditions of tensile stress incipient vascular tissue undergoes a parenchymatous development, are supported by the data of these experiments. The observations afford a clear indication of the diversity of the morphogenetic activity in the growing region. Nutritional, mechanical and other factors are seen to be important in influencing the distribution of tissues during development. The view entertained by comparative morphologists that the vascular system in ferns is of a highly conservative nature and therefore of great value in phyletic studies is to some extent opposed by the data of these experiments. But notwithstanding the several unusual vascular configurations produced as a result of the experimental treatment, there is eventually a return to the typical vascular arrangements of the normal shoot. There is thus a need for harmonizing the data of the causal and phyletic aspects. The more thoroughly the operation of morphogenetic factors extrinsic to the specific hereditary substance is understood, the more critical will be the selection of criteria of comparison for phyletic purposes.

Cytological and histological changes induced by cold temperature in the young shoots of Marquillo × Kenya Farmer wheat dwarf 1

1972 ◽  
Vol 50 (3) ◽  
pp. 403-408 ◽  
Author(s):  
J. D. Mahon ◽  
D. T. Canvin
Keyword(s):  
Apical Meristem ◽  
Leaf Primordia ◽  
Vascular Bundles ◽  
Vascular Differentiation ◽  
Main Shoot ◽  
Histological Changes ◽  
Whole Plant ◽  
Meristematic Activity ◽  
Extensive Cell ◽  
Extent Of Damage

The growth of Marquillo × Kenya Farmer 1 heat plants has been shown to be irreversibly terminated if they are exposed to a 16° temperature when 10 days old and it has been proposed that this low temperature sensitivity proceeds through a rapid inactivation of the shoot apical meristem. Histological and microautoradiographic techniques were used to study the effects of 16° treatment on the morphology and meristematic activity of the young shoots of both Marquillo × Kenya Farmer 1 and normal Marquillo plants.Within 12 h of the beginning of 16° treatment, damaged cells were visible in the young developing leaf and stem tissues and such cells became numerous after longer periods at 16°. The cells most rapidly destroyed were those surrounding the vascular bundles in both leaf primordia and stem tissues and the extent of damage in a tissue was closely related to the stage of vascular differentiation in the adjacent bundles.Cell division in the apical meristem of the main shoot was inhibited even more rapidly. The proportion of cells dividing and the incorporation of 3H-thymidine into the nuclei of meristem cells decreased rapidly at 16° and the reversibility of these effects was similar to that of the whole plant effects.It is suggested that the cessation of growth in Mql × KF 1 exposed to 16° is due to the lack of cell division and that the permanence of this effect is due to the extensive cell destruction that occurs in the meristematic regions.

Morphology and Photoperiodic Responses of Yellow Nutsedge

Weed Science ◽  
1971 ◽  
Vol 19 (3) ◽  
pp. 210-219 ◽  
Author(s):  
L. L. Jansen
Keyword(s):  
Apical Meristem ◽  
Higher Order ◽  
Shoot Development ◽  
Leaf Primordia ◽  
Cyperus Esculentus ◽  
Stages Of Development ◽  
Vegetative Development ◽  
Yellow Nutsedge ◽  
Photoperiodic Responses ◽  
Basal Bulb

Young vegetative clones of yellow nutsedge (Cyperus esculentusL.) were propagated by subdivision of older clones and then grown 6 months under photoperiods of 8 to 24 hr. Early stages of development of basal bulbs, tubers, and flowering structures were characterized in terms of apical meristem activity and differentiation of various foliar appendages: cladophylls, prophylls, leaf primordia, foliar tube development, and involucral leaves. Ramification of the axial stem system was interpreted as a repeating phylogenetic sequence:viz., undifferentiated axial meristem (from basal bulb) å primitive stem (rhizome) å advanced stem (new basal bulb). New photosynthetic leaves differentiated every 4.5 to 5 days, and each exhibited a sigmoid pattern of growth for 24 to 40 days. As photoperiods increased from 14 to 24 hr, certain active vegetative processes—total peripheral shoot development, rhizome proliferation, and rate of higher order shooting—were progressively promoted. The rate of differentiation of indeterminate rhizome tips into basal bulbs (new shoots) was maximum at 16 hr and into tubers at 8 to 12 hr. Delayed tuberization, however, occurred even at the longest photoperiod. Flowering occurred only at photoperiods of 12 and 14 hr. Active vegetative processes were competitive with tuberization, and flowering was competitive with both active and dormant vegetative development.

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