Partial Shoot Research Articles

Canopy Architecture and Sun Exposure Influence Berry Cluster-Water Relations in the Grapevine Variety Muscat of Alexandria.

Climate-change-related increases in the frequency and intensity of heatwaves affect viticulture, leading to losses in yield and grape quality. We assessed whether canopy-architecture manipulation mitigates the effects of summer stress in a Mediterranean vineyard. The Vitis vinifera L variety Muscat of Alexandria plants were monitored during 2019-2020. Two canopy shoot-positioning treatments were applied: vertical shoot positioning (VSP) and modulated shoot positioning (MSP). In MSP, the west-side upper foliage was released to promote partial shoot leaning, shading the clusters. Clusters were sampled at pea size (PS), veraison (VER), and full maturation (FM). Measurements included rachis anatomy and hydraulic conductance (Kh) and aquaporins (AQP) and stress-related genes expression in cluster tissues. The results show significant seasonal and interannual differences in Kh and vascular anatomy. At VER, the Kh of the rachis and rachis+pedicel and the xylem diameter decreased but were unaffected by treatments. The phloem-xylem ratio was either increased (2019) or reduced (2020) in MSP compared to VSP. Most AQPs were down-regulated at FM in pedicels and up-regulated at VER in pulp. A potential maturation shift in MSP was observed and confirmed by the up-regulation of several stress-related genes in all tissues. The study pinpoints the role of canopy architecture in berry-water relations and stress response during ripening.

In Vitro Efficiency of Some Fungicides Against Neoscytalı̇dı̇um dı̇mı̇dı̇atum (Penz.) Crous and Slippers Causing Sudden Shoot Dry on Apricot Trees

Turkey is known as a top producer and exporter of apricots, both fresh and dried. More than half of Turkey's apricot production is provided by Malatya province. There are many pests and diseases affecting apricots in addition to climatic factors such as frost and hail. Partial shoot drying and sudden drying in apricot orchards have increased in recent years. In this study, it was aimed to determine the chemical control possibilities of Neoscytalidium dimidiatum (Penz.) Crous &Slippers, which is one of the fungal agents that cause partial branch drying and sudden drying in apricot orchards in Malatya province by in vitro studies. For this purpose, Kale 4-C isolate of N. dimidiatum collected from Malatya in a previous study was used. Mycelial growth of N. dimidiatum Kale 4-C isolate in PDA were observed in 0 (control), 0.01, 0.03, 0.1, 1, 3, 10, 30 ve 100 μg/mL concentrations of Azoxystrobin 250g/L, Trifloxystrobin %50, Tebuconazole %25, Floupyram 200 g/L+Tebuconazole 200 g/L, Cyprodinil+Fludioxonil %37.5+25, %70 Thiophanate-Methyl and 400 g/L Phosphorous acide fungicides applications. As a result of the study, Floupyram 200g/L+Tebuconazole 200g/L ve Cyprodinil+Fludioxonil %37.5+25 fungicides effectively inhibited the mycelial growth of the fungus.

Variability of the Gender Spectrum in Origanum vulgare L. (Lamiaceae, Magnoliopsida)

Origanum vulgare L. is a gynodioecious species, populations of which include hermaphroditic plants with bisexual flowers and female plants with pistillate flowers. This is a holarctic forest–steppe species belonging to herbaceous perennial plants. The variability of the female-to-hermaphrodite ratio in 26 coenopopulations of O. vulgare from different habitats has been studied. The data on eight populations were obtained in the course of the authors’ studies in southern Siberia, while 18 populations from Eastern Europe were analyzed based on the published data of other researchers. For all habitats, the projective cover of the species was determined according to the standard geobotanical methods. The plants studied represented a long-rhizome life form, so a partial shoot or a partial shrub (ramets) was used as a countable unit. The gender structure of coenopopulations was studied by counting generative plants within transects with an area of 10 to 20 m2. For each population, the total number of plants to be counted was at least 90. A significant positive correlation between the projective cover of O. vulgare in a phytocenosis and the percentage of female plants in coenopopulations was revealed (the Pearson correlation coefficient r = 0.86, p = 0.001). The ANOVA analysis showed no significant difference in the percentage of female plants in six different habitats (Femp = 3.36; Fcrit 5.5 = 5.1; p = 0.05). Taking into account the morphological and reproductive features of different genders of O. vulgare, one can suggest that an increase in the projective cover of the species in a phytocoenosis and an increase in the percentage of female plants in the gender spectrum depend on successful seed regeneration in the phytocenosis.

INFLUENCE OF PARTIAL SPUR LEAVES REMOVAL ON FRUITLET SHEDDING, FRUIT QUALITY AND SHOOT GROWTH IN APPLE TREES AS A BASIS FOR MECHANICAL THINNING

Knowledge of the physiology of natural fruitlet shedding is especially important to insure thinning efficiency in apple production. The effect of partial spur leaf removal on shedding, as well as on fruit quality and bourse shoot growth, was investigated. Removing spur leaves increased shedding, while there was no effect of partial leaf removal on mature fruit quality in terms of weight, firmness and sum of sugars, detected by HPLC-RI and resulted in lower contents of citric, fumaric and shikimic acids, detected by HPLC-UV. Growth of bourse shoots was poorer in treatments with leaf removal. To summarize, a decreased number of spur leaves caused more intensive fruitlet abscission and poorer bourse shoot growth but had no negative influence on fruit size. These results show the potential use of decreasing spur leaf area to stimulate more intensive natural shedding to support fruitlet thinning, which could be used in combination with prospective mechanical thinning.

Features of development of the clonal plant Scutellaria scordiifolia Fischer ex Schrank (Lamiaceae) in Siberia

Ontomorphogenesis of individuals of the clonal stoloniferous vegetative annual plant Scutellaria scordiifolia was studied in natural habitats. Ramets are represented by partial dicyclic shoots with an adventious root system. The ontogenesis of S. scordiifolia can be expressed by a sequence of phases of morphogenesis: [a partial shoot – a branched partial shoot] (v–g3) – a system of partial shoots (g2–g3) – a partial shoot (g2–ss). Individuals annually die off completely, regeneration takes place due to formation of tuberous stolons which are formed on the maternal stolon.

Water relations and drought tolerance of young African tamarind (Tamarindus indica L.) trees

Tamarindus indica L. is an important multipurpose tree, indigenous to Africa, now introduced worldwide and known for its drought tolerance. The effects of drought on tamarinds, especially at seedling stage, are hardly investigated. However, this information is important for its conservation and domestication. In a growth chamber experiment we investigated the water relations of African tamarind seedlings under short-term soil drought stress. Initially tamarind seedlings can be considered as drought-tolerant at the expense of internal water storage reserves as they keep on transpiring (sap flow) and growing (diameter fluctuations). They finally spent 20% of their stem and root water storage reserves and experienced stem water potentials near −3MPa. Therefore, they can be classified as anisohydric. Their risk-taking behavior led to a high rate of seedling mortality (50%) because of whole plant hydraulic failure. They were not hydraulically efficient and they possessed low water storage capacity in stem and root (45%) due to high tissue density. When re-irrigated, remaining seedlings recovered slowly as a consequence of non-stomatal limitations and partial shoot dieback. Although tamarind seedlings show traits related to drought tolerance, we suggest that the species contains some water saving mechanisms. Contrasts with the co-occurring water-conserving tree species baobab (Adansonia digitata L.) are also discussed.

Shoot atmospheric contact is of little importance to aeration of deeper portions of the wetland plant Meionectes brownii; submerged organs mainly acquire O2 from the water column or produce it endogenously in underwater photosynthesis

Partial shoot submergence is considered less stressful than complete submergence of plants, as aerial contact allows gas exchange with the atmosphere. In situ microelectrode studies of the wetland plant Meionectes brownii showed that O(2) dynamics in the submerged stems and aquatic roots of partially submerged plants were similar to those of completely submerged plants, with internal O(2) concentrations in both organs dropping to less than 5 kPa by dawn regardless of submergence level. The anatomy at the nodes and the relationship between tissue porosity and rates of O(2) diffusion through stems were studied. Stem internodes contained aerenchyma and had mean gas space area of 17.7% per cross section, whereas nodes had 8.2%, but nodal porosity was highly variable, some nodes had very low porosity or were completely occluded (ca. 23% of nodes sampled). The cumulative effect of these low porosity nodes would have impeded internal O(2) movement down stems. Therefore, regardless of the presence of an aerial connection, the deeper portions of submerged organs sourced most of their O(2) via inwards diffusion from the water column during the night, and endogenous production in underwater photosynthesis during the daytime.

Elusive but not hypothetical: axillary meristems in Wollemia nobilis

The branches of Wollemia nobilis are unbranched; however, it has been noted that new branches can form from the distal end of damaged ones, and branches can grow from axillary structures once a terminal strobilus has fallen. Tomlinson and Huggett (2011, Annals of Botany 107: 909-916) have recently investigated the formation of these reiterative branches and stated in the title of their paper that 'Partial shoot reiteration in Wollemia nobilis (Araucariaceae) does not arise from "axillary meristems"'. They go on to state 'Further research may reveal the presence of these elusive, but still only hypothetical, axillary meristems'. In this Viewpoint, I argue that Tomlinson and Huggett do not refer to previously published information that indicates that axillary meristems are present in Wollemia nobilis branch leaf axils, and that their anatomical methods were probably not optimal for locating and examining these minute structures. Thus, whilst I would agree that the axillary meristems in branch leaf axils of Wollemia nobilis are elusive, I contend that they are not hypothetical.

Lobe-generating centres in the simple leaves of Myriophyllum aquaticum: evidence for KN1-like activity

The mature morphology of most plants can usually be said to consist of three mutually exclusive organs: leaves, stems, and roots. The vast majority of mature morphologies may be easily grouped into one of these mutually exclusive categories. However, during very early stages of development and in many instances from inception, the division between organ categories becomes fuzzy due to the overlap in developmental processes that are shared between the aforementioned mutually exclusive categories. One such overlap has been described at the gene level where KNOXI homologues, transcription factors responsible for maintaining indeterminate cell fate, are expressed in the shoot apical meristem and during early stages of compound leaf development. This study characterizes the occurrence and spatial localization of mRNA of a KNOXI homologue, MaKN1, during the early stages of development in the simple leaves of Myriophyllum aquaticum, an aquatic angiosperm from the family Haloragaceae exhibiting pentamerous whorls of finely lobed leaves. A 300-bp KNOXI fragment was sequenced from M. aquaticum and used in an RNA localization study to determine the temporal and spatial expression of KNOXI during the early stages of leaf lobe development in M. aquaticum. The developmental sequence of leaves of M. aquaticum was also described using scanning electron microscopy. Lobe development of M. aquaticum occurs in two very distinct regions at the leaf base in an alternating fashion reminiscent of a distichous shoot system. It was discovered that MaKN1 expression is localized to both the shoot apical meristem and early stages of leaf primordia development (P1-P7). Initially, MaKN1 is expressed ubiquitously throughout primordia (P1-P3); however, as lobes develop, MaKN1 becomes localized to recently emerged lobe primordia, and disappears as lobes develop basipetally. The pattern of gene expression is indicative of shared developmental processes during early development between shoots, compound leaves, highly lobed simple leaves and unifoliate simple leaves which lack KNOXI expression. These findings are supportive of Arber's less rigid 'partial shoot' theory, which conceptualizes compound leaves as having shoot-like elements.

Leaf development in Aralia elata in relation to the partial-shoot concept

Aralia elata (Miq.) Seem. has large bipinnate leaves in which the rachis bears pairs of leaflets in the distal region and pairs of rachillae bearing leaflets in the proximal region. A supernumerary leaflet is also inserted on the rachis adjacent to each rachilla. The rachilla and supernumerary leaflet could perhaps represent an axillary/axillant relationship, in which case the whole leaf would have a notable similarity to a shoot system, and could lend itself to interpretation as a partial shoot system. The development of the leaf has been examined with this in mind. The supernumerary leaflets arise separately from, and later than the rachillae with which they are associated. It is concluded from this and other evidence, for instance the orientation of the plane of dorsiventrality of leaf components, that the resemblance of the leaf to a shoot system is coincidental. However the leaf can be interpreted along lines suggested by classical morphology as an example of a palmate-pinnate leaf, with the addition of reiteration of the palmate element at each cycle of initiation of supernumerary leaflets.

Responses of nonstructural carbohydrates to shoot removal and soil moisture treatments in Salix nigra

Aboveground disturbances are common in dynamic riparian environments, and Salix nigra is well adapted with a vigorous resprouting response. Soil moisture stresses are also common, and S. nigra is flood tolerant and drought sensitive. The objective of this study was to quantify nonstructural carbohydrate (NSC) reserves in S. nigra following shoot removal and soil moisture treatments. NSC reserves provide energy for regeneration of shoot tissue until new functional leaves are developed. Three soil moisture treatments: well-watered (W), periodic flooding (F) and drought (D); and three shoot removal treatments: no shoots removed (R0), partial shoot removal (R1), and complete shoot removal (R2) were applied. Plants were harvested when new shoot development was observed (day 13). Statistical significance in the 3 × 3-factorial design was determined in two-factor ANOVA at P < 0.05. Both roots and cuttings were important reservoirs for NSC during resprouting response, with decreases in root (31%) and cutting (14%) biomass in R2 compared to R0. Rapid recovery of photosynthetic surface area (from 15 to 37% of R0) was found in R1. A clear pattern of starch mobilization was found in roots in R0, R1 and R2, with lowest root starch concentration in W, F higher than W, and D higher than F. Shoot starch concentration was lower in F and D compared to W in R0, however, in R1 shoot starch was reduced in W compared to F and D, possibly indicating reduced rates of translocation during soil moisture stress. Evidence of osmotic adjustment was found in roots and shoots with higher total ethanol-soluble carbohydrates (TESC) during soil moisture stress in F and D treatments. Total plant NSC pool was greater in F and D treatments compared to W, and progressively reduced from R0 to R1 to R2. Results indicated negative effects of drought, and to a lesser extent periodic flooding on resprouting response in S. nigra, with implications for reduced survival when exposed to combined stresses of aboveground disturbance and soil moisture.

Activities of starch hydrolytic enzymes and starch mobilization in roots of Caragana korshinskii following above-ground partial shoot removal

In many resprouting plants, carbohydrates are stored as starch in roots and will be mobilized to support above-ground tissue regrowth after shoot damage. Our objective was to determine how activities of starch hydrolytic enzymes change damage-induced starch mobilization in Caragana korshinskii roots after above-ground tissue loss. Zero percent (control), 30% (30% RSL), 60% (60% RSL) of main shoot length, and 25% (25% RSN), 50% (50% RSN), and 100% (100% RSN) of main shoot number were removed. Compared with control plants, clipping accelerated the reduction of starch in the roots, increased sucrose flux per flower per hour and nectar production per flower per day in 30% RSL, 60% RSL, 25% RSN, and 50% RSN treatments, and improved vegetative growth in 100% RSN treatment. All treatments had similar total nonstructural carbohydrate (TNC) concentrations in leaves, shoots, and stems with the exception of 100% RSN with higher TNC concentration in shoots. Both α-, and β-amylase activities were enhanced by clipping, the former being more strongly correlated with starch degradation in the roots than the latter. The other two possible starch-breaking enzymes, α-glucosidase, and starch phosphorylase showed no significant differences in the activities between treatments. The results suggest that starch degradation in the roots of C. korshinskii was regulated by α-amylase activity and more mobilized starch was used to support vegetative growth in 100% RSN treatment and support sexual reproduction followed by other clipping treatments.

Population biology of Pogonia japonica in Russia and Japan

Abstract Pogonia japonica (Orchidaceae) is a clonal plant forming numerous adventitious shoots on long perennial roots. Seeds remained dormant for 3 years or more and rarely germinated. Populations consisted of ramets of different ages. Each ramet was a partial shoot growing vertically and monopodially before changing to sympodial growth after the first flowering. Annual growth consisted of two internodes making it easy to determine the shoot age. Three to 12 ramets were connected by a common root system. This might provide rapid development of ramets. In favorable habitats, vigorous ramets started flowering in the second or third year, and flowering lasted for another 3–4 years. In unfavorable habitats, preflowering shoot development took 3–5 years, or it died before or just after the first flowering. Ramets remained alive but senescent for 1–2 years after the last flowering. Disconnection of 2–4‐year‐old shoots was a normal process of vegetative reproduction. Some isolated mature shoots stayed dormant for 1–2 years. Young shoots disconnected within the first year usually died. Vegetative mature shoots predominated in the Russian populations, whereas young ramets were more numerous in the Japanese populations. The proportion of flowering to vegetative shoots averaged 15%, but reached as high as 55% in one Japanese population. Fruiting was high (80%) in Russian populations, but in some Japanese populations it dropped to zero after all fruits were damaged by insects. Differences in plant size and population structure reflected differences in ecological conditions more than geographic difference.

Fruit production of shrub, Caragana korshinskii, following above-ground partial shoot removal: mechanisms underlying compensation

A number of studies have showed that under some conditions plant may partially, fully or overcompensate for tissue loss, however, the mechanisms underlying compensation are not well understood and still need to be researched. We examined the ability of Caragana korshinskii to compensate for fruit production after above-ground partial shoot removal. Fruit production of 30% main shoot length removal (30% RSL) and 25 and 50% main shoot number removal (25% RSN, 50% RSN) resulted in overcompensation and the response of 60% main shoot length removal (60% RSL) was full compensation. Plants’ responses associated with compensation included (1) greater reproduction efficiency (RA); (2) increased fruit set; (3) decreased fruit abortion; (4) increased seed number per pod; and (5) higher individual seed biomass. These responses may have resulted from more nectar production per flower, more sucrose flux per pod and more sucrose flux per seed of clipped plants, which may in turn have resulted from (1) drawing upon more non-structural carbohydrate (TNC) from roots to supply flower bud development and the flush of new foliage; (2) supplying more photosynthetic assimilation to fruit development owing to increases in leaf-level photosynthetic rates. Increases in leaf-level photosynthetic rates may be caused by more nutrient (nitrogen) and water availability per unit area of resource leaves after clipping.

A STUDY ON VEGETATIVE COMPENSATORY GROWTH OF SHRUB, CARAGANA KORSHINSKII, UNDER DIFFERENT CLIPPING TREATMENTS IN DISTURBANCE ENVIRONMENT

Background and Aims After browsing or clipping,Caragana korshinskii can compensate for loss of biomass,which is the foundation for repeated use of resources of this species. However,the pattern of vegetative compensatory growth under different clipping treatments is still poorly understood. Methods In order to test the effects of removal of partial shoot length (RSL) and partial shoot number (RSN) on vegetative growth,we removed 30% (30%RSL),60% (60%RSL) of main shoot length,and 25% (25%RSN),50% (50%RSN),and 100% (100%RSN) of main shoot number. Key Results Clipped shrubs overcompensated for tissue loss,and current year shoot number per shoot,current year shoot length,current year shoot biomass per shoot and current year shoot biomass per shrub were higher than those of the control. The control,30%RSL and 60%RSL shrubs did not resprout after clipping,while 25%RSN,60%RSN and 100%RSN treatments did resprout and the biomass per shrub increased when more shoot biomass were removed. Differences in resprout number per removal shoot,resprout length,individual resprout biomass were not significant between 25%RSN and 50%RSN treatment,but resprout number per removal shoot,resprout length,individual resprout biomass of both were less than those of 100%RSN treatment. Fruit production in clipping treatments was higher or equal to that of the control with the exception of 100%RSN,which grew no fruit. There was a negative relationship between annual shoot biomass and fruit production with the exception of the control,which had less fruit production and the annual shoots almost did not grow. During growth season,biomass of current year vegetative growth increased quickly from current year's shoot growth to fruit ripeness. In the following three months,from fruit ripeness to leaf abscission,however,it increased slowly. Conclusions 100%RSN treatment may be a reasonable mode to prompt shrubs to recover quickly from damage. Plants' responses associated with compensation may include: increased branching or tillering after alteration of the apical dominance,increased availability of water and/or nutrients after the change in the ratio of shoot to root,and remobilization of resources reserved in roots to aboveground organs. Decreased allocation of resources to reproductive growth may be another important mechanism for 100%RSN shrubs to compensate for the loss of organs.

Partial shoot removal increases net CO2 assimilation and alters water relations of Citrus seedlings

Effects of defoliation on partial shoot removal by decapitation on seedling growth, water use and net gas exchange of remaining basal leaves, were examined in Citrus spp. Shoot and root growth rates were manipulated to test for effects of growth demands on net gas exchange. Partially defoliated plants had higher leaf pressure potentials, root conductivities and rates of water use than intact control plants. Shoot regrowth occurred at the expense of root loss. Basal leaves on defoliated plants consistently had higher rates of CO(2) assimilation (A) than leaves on intact plants. Stomatal conductance (g(s)) changed little after defoliation so the higher A of leaves on defoliated plants lowered the ratio of intercellular to ambient CO(2) concentration (C(i)/C(a)) in the mesophyll. In some cases, g(s) increased with A in defoliated plants but C(i)/C(a) was not affected. Stomatal conductance only limited A when intact seedlings were stressed by root confinement in small pots or when leaves were exposed to high vapor pressure deficits during gas exchange measurements. Increased carbon demand for shoot regrowth increased photosynthetic capacity and was more important than stomatal responses in determining A after partial shoot loss.

Expression of shoot features in early leaf development of Murraya paniculata (Rutaceae)

The early development of the pinnately compound leaves in Murraya paniculata was studied using both epi-illumination and scanning electron microscopy as well as semithin plastic sectioning of the same specimens that were illustrated by means of epi-illumination. It is shown that morphological conclusions may be influenced by technical approaches such as the plane of sectioning. If the developing leaves are sectioned in the (median) sagittal plane, they appear to be rather different from stems and shoots. If, however, they are sectioned in the frontal plane, perpendicular to the sagittal plane, they appear more shoot-like in early development. Their apex could be described in terms of a tunica-corpus organization and the leaflet primordia are initiated like leaf primordia on a shoot tip with distichous phyllotaxy sensu lato. Subsequently, due to differential growth, reorientation of the leaflets occurs in one plane. Thus, the planar structure of the pinnate leaf is ontogenetically secondary. From a phylogenetic perspective, at least two conclusions are possible for plants with pinnate leaves such as those of Murraya: (i) if the ancestor of a pinnate taxon had simple leaves, the pinnate condition arose through homeosis, i.e., the expression of shoot features in leaf sites; (ii) if the ancestor of a pinnate taxon did not have simple leaves, the shoot-like early development of the pinnate leaves may indicate a common evolutionary basis of shoots and pinnate leaves in primitive branching systems. Since it is generally thought that the most primitive angiosperms have simple leaves, the homeotic hypothesis appears to be the preferred hypothesis for the origin of compound leaves in flowering plants. Key words: leaf development, comparative morphogenesis, shoot–leaf relationships, partial shoot theory of the leaf, homeosis.

Carbohydrate mobilization following shoot defoliation and decapitation in hybrid poplar.

The effects of shoot defoliation, decapitation, and disbudding on carbon mobilization were investigated in rooted cuttings of Populus maximowiczii x nigra L. 'MN9'. Ten days after complete shoot defoliation or decapitation, the stem starch concentration of treated plants declined to one-half that of intact plants, and there were similar or greater reductions in the concentrations of glucose, fructose, sucrose, galactose, and shikimic acid. Partial shoot defoliation (50%) and complete disbudding had no effect on stem starch concentration, but stem sucrose concentration was reduced in all treatments. Sucrose depletion preceded and may have induced other changes in the carbon status of plants subjected to leaf or shoot removal. Four days after shoot decapitation, the sucrose concentration of roots of treated plants was reduced to 25% of that of intact plants. However, the concentrations of fructose and glucose increased in the roots of treated plants and was followed by the accumulation of shikimic acid, salicyl alcohol, unknown compound A and salicin. The possible role of increased concentrations of root organic solutes in the water relations and regrowth process of decapitated plants is discussed.

Shoot initiation in the leaflet axils of compound leaves from micropropagated shoots of juvenile and mature common ash (Fraxinus excelsiorL.)

Micropropagation of a mature ash tree has been achieved for the first time. The main obstacle encountered was contamination of the initial explants with microorganisms. However, once apparently sterile shoots had been obtained, shoot proliferation was achieved most effectively by culturing nodes on Driver and Kuniyuki walnut medium containing 22.2 μM benzyladenine. After several subcultures, a species of Bacillus appeared with the mature culture line, but it did not affect shoot or root development adversely. With successive subculturing, shoots of the mature ash clone became progressively easier to root. Pinnately compound leaf explants from micropropagated shoots of two seedlings and the mature tree, placed on to Murashige and Skoog-based culture media supplemented with 4.4μM-phenyl-N-1,2,3-thiadiazol-5-ylurea, produced shoot buds. Most buds developed from the rachis at the points of attachment of the leaflets. When transferred to Driver and Kuniyuki walnut medium, buds from one of the seedling lines and from the mature tree, elongated into shoots, and were subsequently transferred to media for micropropagation and rooting. Shoot initiation is discussed in relation to possible occurrence of vestigial meristems in the axils of leaflets and the partial shoot theory of leaf structure.

Shoot Apex Organization, Leaf Development and Behaviour of Vegetative Bud in Adiantum incisum Forsk.

Shoot apex organization, leaf development and the initiation of apical bud from the rachis tip have been studied in A. incisum Forsk. The shoot apex has an apical meristem and a leaf initiates from a group of cells. The maturation of leaf is acropetal. The lenticular apical cell of the leaf looses its entity and gives rise to a group of columnar prismatic cells. From these cells an inverted pyramidal apical cell differentiates during the conversion of leaf tip into a shoot bud. Morphological nature of leaf has also been discussed and partial shoot hypothesis appears to be the best to understand the leaf as morphology and anatomy of compound leaf seems to give more evidence in support of partial shoot hypothesis.