Foliage Leaf Research Articles

Secondary stress in several edible citrus cultivars caused by heavymetal air pollution

Edible plants can be contaminated by air diffused pollutants. Research on stress caused by pollutants, which involves the biomonitoringof ornamental trees in the city of Palermo, including Citrus fruits,which are of considerable importance in Sicily's agricultural economy andagroindustrial programmes, has been carried out.Morphological observations of ornamental Citrus revealed anevergreen foliage and excellent leaf characteristics, even in environmentalcontexts where other plant species were found to have undergone morpho-anatomical changes.Stress symptoms related to the presence of lead which, supposedly, couldhave been absorbed by the pericarp or by the pulp of the navel orangebrasiliano N.L. 92 and 2 grapefruit cultivars were observed. Fruits, sections of pulp and leaves of brasiliano oranges collected from thefield in Lascari (Palermo, 38° N) of the “Centro di studio per ilmiglioramento genetico degli agrumi” (C.N.R. Palermo) and from theexperimental sites of the Faculty of Agriculture in the Parco d'Orleans inPalermo were compared. Fruits of the cultivars Ruby Red Star and Marshpicked from the field located in the Parco d'Orleans were also objects ofobservation.Lead, iron, manganese and copper were measured by atomic absorptionspectrophotometry and we conclude that, in these particular cultivationconditions, the brasiliano orange would not appear to be a suitable markerspecies and seems to be safe for agro-alimentary use.

Branching Principles Governing the Architecture of Cornus kousa (Cornaceae)

The complex structure of the crown of Cornus kousa, generally five-forked in vegetative branching and two-forked in reproductive branching, is analysed quantitatively and described by two basic branching principles: decussate phyllotaxy and the resetting rule for planes of branching. Most Cornus species have opposite, decussate phyllotaxis. The leaf pair (with axillary buds) defines the branching plane of a node. Because of regular phyllotaxis, the fundamental branching pattern is that every branching plane along an axis is perpendicular to the preceding one. However, the first node of a lateral horizontal shoot always has a horizontal branching plane; we term this the resetting rule. We observed that resetting occurs when the first nodes initiated in the vertical plane are repositioned by a twisting of their first internodes. All later nodes alternate directions, i.e. show usual decussate alternation. Foliage leaf nodes usually produce three-forked branchings. When vegetative winter buds are formed, a foliar node and adjacent scale leaf node produce a five-forked branching. When reproductive winter buds with a terminal inflorescence are formed, the last foliar node and two adjacent scale leaf nodes can produce a variety of branchings but usually produce an equal two-forked branching. To understand better the architecture in C. kousa, we contrast it with C. capitata which does not produce buds with scale leaves and whose vegetative nodes are clearly separated.

A mechanical perspective on foliage leaf form and function

The mechanical behaviour of large foliage leaves in response to static and dynamic mechanical forces is reviewed in the context of a few basic engineering principles and illustrated in terms of species drawn from a variety of vascular plant lineages. When loaded under their own weight or subjected to externally applied forces, petioles simultaneously bend and twist, and thus mechanically operate as cantilevered beams. The stresses that develop in petioles reach their maximum intensities either at their surface or very near their centroid axes, where they are accommodated either by living and hydrostatic tissues (parenchyma and collenchyma) or dead and stiff tissues (sclerenchyma and vascular fibres) depending on the size of the leaf and the species from which it is drawn. Allometric analyses of diverse species indicate size‐dependent variations in petiole length, transverse shape, geometry and stiffness that accord well with those required to maintain a uniform tip‐deflection for leaves with laminae differing in mass. When dynamically loaded, the laminae of many broad‐leaved species fold and curl into streamlined objects, thereby reducing the drag forces that they experience and transmit to their subtending petioles and stems. From a mechanical perspective, the laminae of these species operate as stress‐skin panels that distribute point loads more or less equally over their entire surface. Although comparatively little is known about the mechanical structure and behaviour of foliage leaves, new advances in engineering theory and computer analyses reveal these organs to be far more complex than previously thought. For example, finite‐element analyses of the base of palm leaves reveal that stresses are decreased when these structures are composed of anisotropic as opposed to isotropic materials (tissues).

四季成り性イチゴ「サマーベリー」の一年生苗における花房発生に及ぼす温度と日長の影響

四季成り性イチゴの'サマーベリー'を供試して, 16週間にわたる温度と日長が花房の発生に及ぼす影響を調べた.その結果, 昼温/夜温が20/15℃と25/20℃の場合, 8時間日長でも24時間日長でも処理期間を通して開花花房が認められた.30/25℃の場合, 8時間日長では開花花房が全く認められなくなった.一方, 24時間日長では葉無着生腋花房の発達が著しく促進された.以上の結果, 'サマーベリー'は20/15℃から25/20℃の温度域では花房の発生について量的長日植物の反応を示し, 30/25℃では質的長日植物の反応を示すものと考えられた.

Short-term changes of response indicators of ecosystem status in broadleaved forests in Tuscany (Central Italy).

The status of different response indicators of forest condition were measured and assessed between 1995 and 1997 at 6 Permanent Monitoring Plots (PMPs) in Tuscany (central Italy), where beech, holm oak and Turkey oak are the most frequent tree species. Foliage transparency, leaf damage and crown dieback have changed significantly over the monitoring period. Leaf area, length of the current year shoots, and total leaf area changed as well, but only for Turkey oak. Changes were consistent between and within the plots. Different indices of plant diversity showed marked changes, apparently linked to natural dynamics within individual ecosystems. These rapid and contrasting fluctuations in the various indicators of forest ecosystem make it difficult to derive a synthesis about the general condition of ecosystems and - especially - about the effects of air pollution.

Modeling the effect of physiological responses to green pruning on net biomass production of Eucalyptus nitens.

Green pruning of Eucalyptus nitens (Deane and Maiden) Maiden increases instantaneous rates of light-saturated CO(2) assimilation (A), and changes patterns of total leaf area and foliage distribution. We investigated the importance of such changes on the rate of recovery of growth following pruning. A simple process-based model was developed to estimate daily net biomass production (G(d)) of three-year-old plantation-grown trees over a 20-month period. The trees had been pruned by removal of 0, 50 or 70% of the length of green crown, equivalent to removal of 0, 55 or 88% of leaf area, respectively, when the plantation verged on canopy closure. Total G(d) was reduced by only 20% immediately following the 50%-pruning treatment, as a result of both the high leaf dark respiration and low A in the portion of the crown removed compared to the top of the crown. Pruning at the time of canopy closure preempted a natural and rapid decline in G(d) of the lower crown. Although leaf area index (L) was approximately 6.0 at the time of pruning, high light interception (95%) occurred with an L of 4.0. The 50%-pruning treatment reduced L to 3.5, but the physiological responses to pruning were sufficient to compensate fully for the reduction in intercepted radiation within 110 days of pruning. The 70%-pruning treatment reduced L to 1.9, and reduced G(d) by 77%, reflecting the removal of branches with high A in the mid and upper crown. Physiological responses to the 70%-pruning treatment were insufficient to increase G(d) to the value of unpruned trees during the study. Model sensitivity analysis showed that increases in A following pruning increased G(d) by 20 and 25% in the 50- and 70%-pruned trees, respectively, 20 months after pruning. Changes in leaf area/foliage distribution had a greater effect on G(d) of 50%-pruned trees (47% increase) than did changes in A. However, the reduction in photosynthetic potential associated with the 70%-pruning treatment resulted in only small changes in leaf area/foliage distribution, which consequently had little effect on G(d). The effects of physiological processes occurring within the crown and in response to green pruning on G(d) are discussed with respect to pruning of plantations.

休眠期における四季成り性イチゴの栄養生長と生殖生長を誘導する温度と日長条件

Effects of temperature and photoperiod on vegetative and reproductive growth were investigated in everbearing strawberry (Fragaria×ananassa Duch. cv. 'Summerberry') plants. Runner plants grown in a nursery field until November were transplanted to clay pots, and were grown in growth chambers at a 12-hr day/night setting of 20/15°, 25/20°, and 30/25°C, under either constant light (24-hr, long-day) or an 8-hr (short-day) photoperiod. The treatments were started on December 1. 1. At 30/25°C, the appearance of an inflorescence was inhibited under short-day. By contrast the number of inflorescences was remarkably increased until 10 weeks after the start of the long-day treatment. The production rate of axillary inflorescences which developed from subtended axillary bud without a foliage leaf was increased remarkably under long-day. These results were similar to those of non-dormant plants. 2. At 20/15°C and 25/20°C, more inflorescences were initiated under the long-day than under the short-day treatment. At 20/15°C, the photoperiod was not effective on the development of inflorescences. 3. Under the 8-hr photoperiod, the petioles grew longer at 25/20° and 30/25° than those on plants kept at 20/15°C ; conversely, under the 24-hr photoperiod, the average length of the petioles became shorter at the higher temperatures with time compared to that of plants kept at 20/15°C.

Antidaphne hondurense Kuijt, a Second Mesoamerican Species of Eremolepidaceae

The second continental species ofAntidaphne north of Colombia, A. hondurense Kuijt (Eremolepidaceae), is described and illustrated. The species is monoecious and related to A. andina Kuijt and A. wrightii (Grisebach) Kuijt. Antidaphne hondurense Kuijt, sp. nov. TYPE: Honduras. Comayagua: (San Juanillo), Camino a San Juanillo, 11 km al Suroeste de Siguatepeque, Reserva Biol6gica Cordillera de Montecillos, bosque nublado latifoliado, 14?29'N, 87053'W, 1890 m, sobre Quercus (No. 218), Mej]a Darto 219 (holotype, MO; isotype, LEA). Figures 1-6. Folia elliptica vel ovata, sessiles, apice obtusa. Flores distributione monoica, floribus pistillatis singulis, staminatisque in spicis brevissimi. Inconspicuous, glabrous plants 0.5 m diam., sympodial in habit, branches forking regularly, internodes strongly angular when young, ca. 1 cm long. Leaves to 3 X 2 cm, elliptical to ovate, sessile, fairly thin but leathery, apex rounded, base obtuse to acute, attachment 2 mm wide, from which numerous palmate veins reach far into the blade. Monoecious; flower buds 1 x 1 mm, globular; petals 4, triangular. Male inflorescences apparently originating in the axils of the prophylls associated with the female flower and thus paired, and developing later than the female flower; male flowers with 4 free stamens 0.5 mm long opposite petals and surrounding a central disk, anthers with 4 locules, flowers in a very short (3 mm), squamate, indeterminate spike, 6 per spike, each sunken in small alveolus above a scale-leaf. Female flower in cupulate bract, which is placed between two somewhat naviculate prophylls with lacerate margin and acute tip, the combined structure axillary to, and solitary in the axil of, a foliage leaf; style 0.5 mm long, stout and straight, with flat stigmatic surface. Fruit ca. 8 mm diam., spherical or nearly so, smooth, purple, the small, persistent petals recurved. Antidaphne hondurense represents the second continental species of Eremolepidaceae north of Colombia, the other species, A. viscoidea Poeppig & Endlicher, ranging from Chiapas to Bolivia (Kuijt, 1988). The latter has not, however, so far been collected in Honduras. In fact, A. hondurense is more closely related to A. andina Kuijt from the northern Andes, and possibly to A. wrightii (Grisebach) Kuijt from the Greater Antilles, and forms an interesting geographical connection between the two. All three species, in contrast to A. viscoidea, are monoecious, the former two with one female and several male flowers occupying each leaf axil, at least the female flowers not associated in inflorescences; furthermore, female flowers are 4-partite rather than 2or 3partite, as in A. viscoidea; and male flowers bear petals in species other than A. viscoidea, which is apetalous. Antidaphne hondurense differs from A. andina and A. wrightii in its sympodial habit, leaf shape, and in the much larger, more spherical, and purple fruit. I am assuming that at least the young plants have basal roots, as they do in the other species of Antidaphne. The plant is sympodial-a condition that has frequently evolved in various mistletoe genera, including Eubrachion of Eremolepidaceae (Kuijt, 1988)-but the particular form which this branching pattern takes in A. hondurense seems to be unique at least among mistletoes. As mentioned in the above description, each leaf is normally associated with one female flower, placed in a median position, plus two collateral buds; the latter, in turn, may be flanked by one or two smaller buds. However, the largest pair of collateral buds of the uppermost leaf develop into two more or less symmetrical innovations. Thus a more or less regularly forked plant develops, even though the alternate phyllotaxy of the species would seem to prohibit it. Paratype. HONDURAS. Comayagua: Cerro Azul Me~imbar, 10.5 km E of lago Yojoa, dense hardwood cloud forest with bamboo understory on ridge leading to Cerro Azul peak, 14018'N, 87053'W, 1850 m, Thomas 617 (MO). NovoN 8: 402-404. 1998. This content downloaded from 157.55.39.176 on Sat, 09 Apr 2016 06:46:03 UTC All use subject to http://about.jstor.org/terms Volume 8, Number 4 Kuijt 403 1998 Antidaphne hondurense from Mesoamerica

Aulonemia bogotensis (Poaceae: Bambusoideae), a New Species from the Cordillera Oriental of Colombia

A new species of Aulonemia from the paramos of the Cordillera Oriental, Cundinamarca, Colombia, is described and illustrated. Aulonemia bogotensis is distinguished by its diminutive size, abaxially tomentose foliage leaf blades, and spikelets with muticous lemmas. Two similar Colombian endemics, A. pumila and A. trianae, are compared and contrasted with the new species.

Determination of Abamectin in Some Forest Matrices by Liquid Chromatography with Fluorescence Detection

A liquid chromatographic method was developed and validated for the determination of abamectin B1a residues in some terrestrial (balsam fir and oak foliage, sandy and clay loam soils and leaf litter) and aquatic (stream water and sediment) forest matrices. The processed foliage, soil, litter, and sediment were fortified with abamectin and extracted with ethyl acetate. The fortified steam water was extracted with dichloromethane. Aliquots of crude extracts were cleaned with Florisil® column chromatography and the purified extracts were derivatized using 1-methylimidazole and trifluoroacetic anhydride. The derivatized abamectin was analysed by reverse phase liquid chromatography, with a fluorescence detector set at 232 nm excitation and 461 nm emission wavelengths. A Spherisorb® ODS2, 5μm, 250 × 4 mm column was used. The samples were run isocratically using methanol-water as the mobile phase. Mean recoveries for the analyte ranged from 83.0 to 93.0%, with a coefficient of variation from 6.3 to 12.4%. Limits of detection and limits of quantitation for solid matrices ranged from 0.10 to 0.20 and from 0.30 to 0.60 ng/g, respectively, and for stream water the corresponding values were 0.003 and 0.009 ng/mL. The procedure provides a reliable and sensitive method for determining abamectin B1a residues in forest matrices.

Ｚｅｐｈｙｒａｎｔｈｅｓ ｃａｎｄｉｄａ Ｈｅｒｂ．の生育開花に及ぼす温度の影響

The growth periodicity of Zephyranthes candida grown outdoors and the effect of temperature on the initiation and development of flower buds were investigated.A bulb has a sympodial branching system; each unit of the sympodial branch is com-.posed of 2 foliage leaves with a circular base and 1 foliage leaf with semi-circular base in 1/2 alternate arrangement from the base upwards and terminates in an inflorescence with 1 floret. During the growing period, extending from spring to autumn, repeated sympodial branching results in 3-4 inflorescences.In October, after the flowering season, 2 inflorescence primordia remain in each bulb. The first inflorescence is at carpel initiation stage and the pollen mother cell is at the tetrad stage; the pollen grains mature and become functional between June and August of the following year. Anthesis occurs from July to September.When plants with inflorescences at carpel differention stage were moved to a growth chamber kept at 10°, 15°, 23° or 30 °C, plants transferred to 23 °C chamber developed flower buds most rapidly and reached the pollen formation stage 4 months later and bloomed after 20 days. Plants kept at the other temperature regimes had fewer inflorescences and flowered later.In plants kept continuously at 23 °C from October, the first inflorescence flowered in March of the following year. During the growing period for about 13 months, these plants produced 4.7 flowering inflorescences and initiated 5.1 inflorescences by repeated sympodial branching.In a commercial forcing trial, plants kept at a min. 20 °C from early March flowered in May, 2 months earlier than the natural flowering time.

The Concept of Morphological Polarity and its Implication on the Concept of the Essential Organs and on the Concept of the Organisation Type of the Dicotyledonous Plant

Dicotyledons are polarly organised in several ways. In plant morphology polarity, a principle, allowing comparison of different plant structures has until yet not been studied. A division**.of the plant in shoot and root as polar structures leads to the distinction of four instead of three basic organs: leaf, shoot axis, root axis and root cap together with the root hairs. The flower is a1so polarly organised, its poles are formed by the carpels and the stamens. The foliage leaves are also polarly organised which is reflected by the morphological relationship of foliage leaf, stamen and carpel. The stamen uses the hypophyll*** as base of construction and the carpel uses the epiphyll**** as base of construction. Hypophyll and epiphyll are the two poles of the foliage leaf. Root and shoot, the polar entities of the vegetative plant and stamen and carpel, the polar entities of the generative plant are, morphologically correlated. Stamen and carpel can be understood as a combination of the basic organs of vegetative and generative parts of the plant. The basic organs of the generative plant are pollen grain and embryo sack with their gametophytes. The quantitative comparison of variable proportions is supplemented by a qualitative comparison of polarities. The result is that the organisation type of the Dicotyledons can yet be understood as constituted of morphological related parts. * in german Grundorgane ** in german: Gliederung *** in german: Unterblatt **** in german: Oberblatt 1. INTRODUCTI0N

Localization of benzoxazinones that occur constitutively in wheat seedlings.

Occurrence and localization of novel antimicrobial and antifeeding compounds in wheat, 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), and their glucosides, were examined by staining wheat plants (Triticum aestivum L.) in the juvenile stage of growth by ferric chloride. The methanol extracts of the stained plant tissues gave a characteristic blue color, which was shown by spectroscopic and chromatographic analyses to be exclusively due to benzoxazinones. When ferric chloride was applied to the root in the seedlings, the blue color immediately developed, the staining being strongest at the tip region and becoming lighten towards the basal part. The staining pattern of the radicle in the pre-emerging seed was similar to that in the root, but the coleorhiza was not stained. Little staining was observed in the epidermal layer of the leaf sheath in the shoot but the underlying tissue was stained strongly. The foliage leaf folded in the sheath was also stained, but less intense than the shealth tissue. It is suggested that the DIBOA and DIMBOA are produced within the stained region of the leaf and root. Together with previous findings that the benzoxazinones appear constitutively in wheat during the juvenile stage of growth. their localized occurrence in the tissues exposed to microbial and insect attacks suggests that they act as defense compounds during this vulnerable plant stage.

Transfer of exogenous auxin from the phloem to the polar auxin transport pathway in pea (Pisum sativum L.)

When [1-14C]indol-3yl-acetic acid ([1-14C]IAA) was applied to the upper surface of a mature foliage leaf of garden pea (Pisum sativum L. cv. Alderman), 14C effluxed basipetally but not acropetally from 30-mm-long internode segments excised 4 h after the application of [1-14C]IAA. This basipetal efflux was strongly inhibited by the inclusion of 3.10−6 mol· dm3N-1-naphthylphthalamic acid (NPA) in the efflux buffer. In contrast, when [14C] sucrose was applied to the leaf, the efflux of label from stem segments excised subsequently was neither polar nor sensitive to NPA. The [1-14C]IAA was initially exported from mature leaves in the phloem — transport was rapid and apolar; label was recovered from aphids feeding on the stem; and label was recovered in exudates collected from severed petioles in 20 mM ethylenediaminetetraacetic acid. No 14C was detected in aphids feeding on the stems of plants to which [1-14C]IAA had been applied apically, even though the internode on which they were feeding transported considerable quantities of label. Localised applications of NPA to the stem strongly inhibited the basipetal transport of apically applied [1-14C]IAA, but did not affect transport of [1-14C]IAA in the phloem. These results demonstrate for the first time that IAA exported from leaves in the phloem can be transferred into the extravascular polar auxin transport pathway but that reciprocal transfer probably does not occur. In intact plants, transfer of foliar-applied [1-14C]IAA from the phloem to the polar auxin transport pathway was confined to immature tissues at the shoot apex. In plants in which all tissues above the fed leaf were removed before labelling, a limited transfer of IAA occurred in more mature regions of the stem.

Six New Species of Neurolepis (Poaceae: Bambusoideae: Bambuseae) from Ecuador and Peru

Six new species, Neurolepis asymmetrica, N. fimbriligulata, N. Iaegaardii, N. nana, N. rigida, and N. villosa, are described and illustrated. Two subspecies are recognized within N. fi;mbriligulata: N. fiimbriligulata subsp. peruviana and subsp. ,7imbriligulata. All taxa except for N. f mbriligulata subsp. peruviana are endemic to Ecuador; N. fimbriligulata subsp. peruviana is known only from Peru. These species were all formerly included within a broadly defined N. aristata (Munro) Pilger because of the presence of an awn on glumes I and II. A table comparing the six new taxa in Ecuador and N. aristata is provided. Revision of the high Andean bamboo genus Neurolepis Meissner for the Flora of Ecuador has revealed the existence of six new species, which are here described and illustrated. All six, as well as N. ac74minatissima (Munro) Pilger, N. stuebelii (Pilger) Pilger, and N. weberbaueri Pilger, were previously included within a very broadly circumscribed N. aristata (Munro) Pilger based on the presence of a well-developed awn on glumes I and II (Soderstrom, 1969), but discontinuities in variation and distribution among these six taxa are sufficient to warrant recognition at the species level. Neurolepis acuminatissima, N. stuebelii, and N. weberbaueri are now recognized as species distinct from N. aristata (Clark, unpublished data). A total of 12 described species of Neurolepis, including the six described herein and N. stuebelii and N. weberbaueri, is now known from Ecuador. With the exception of N. fimbriligulata and N. Iaegaardii, the other species are each restricted to one cordillera or the other in Ecuador. Among the new taxa, N. asymmetrica, N. nana, and N. rigida occur in the Eastern Cordillera, whereas N. villosa is found only in the Western Cordillera. Neurolepis fimbriligulata is principally from the Western Cordillera, with one population on the western slope of the Eastern Cordillera, and conversely, N. Iaegaardii is primarily from the Eastern Cordillera, with one population in the Western Cordillera. The lack of vegetative branching of the aerial culms is characteristic of Neurolepis (McClure, 1973; Davidse & Clark, 1996). Rhizome bracts intergrade into culm leaves acropetally along each culm, making it difficult to distinguish between the two. Culm leaves usually exhibit blades, but successive culm leaves each produce a longer blade, which adds to the difficulty of characterizing the culm leaves; therefore descriptions of the culm leaves, usually an important and even diagnostic source of characters in other bamboo genera, are brief. The transition from culm leaves to foliage leaves is usually rather abrupt in Neurolepis. Foliage leaf morphology is very useful in distinguishing among species of Neurolepas. The juncture of the sheath and blade, including the sheath summit, the inner ligule, and the blade base, is critical for species identification, and should always be collected. Because the development of the pseudopetiole is so variable among the species of Neurolepis, the length of the pseudopetiole is excluded from the length of the blade in the descriptions. Terminology to describe the inflorescences follows Troll (1964), Soderstrom and Londono (1988), and Weberling (1992). The synflorescence was measured from the lowermost primary paracladium (or paracladia) to the apex of the main axis (rachis); a measurement for the peduncle is given separately, where data are available. Variation in the development of spikelets, particularly the awns of glumes I and II, is correlated with position in the synflorescence. Spikelets terminating the main axis and the primary and secondary paracladia are often slightly larger and exhibit the greatest awn development, whereas those spikelets terminating tertiary or higher order paracladia are often smaller and show markedly less awn development. Measurements were taken from the most and least developed functional spikelets to provide a full range of variation. Measurements for the descriptions and comparisons in Table 1 were taken from virtually all specimens cited in this paper, including holoand isotypes. When possible, two leaves were measured per specimen, but frequently only one complete leaf was available. Usually two spikelets per flow. . erlng speclmen were measurec . NOVON 6: 335-350. 1996. This content downloaded from 157.55.39.47 on Sun, 17 Jul 2016 05:28:49 UTC All use subject to http://about.jstor.org/terms

PROTOXYLEM MATURATION IN THE SEEDLING LEAF OF WHEAT

Protoxylem (PX) maturation was followed in vascular bundles of the first foliage leaf (L#1) of wheat seedlings, using clearings and sectioned materials to assess development changes. L#1 contained seven to 11 longitudinal bundles. The seven bundles with largest diameters contained PX vessels, but the number of bundles with PX varied with leaf length. Repeated vessel maturation maintained PX continuity as older vessels collapsed due to leaf extension. Thus, the number of PX vessels in each bundle was also a function of leaf length, and the PX content of a bundle was a function of the stage of leaf development and how soon during leaf development the bundle attained mature PX. Distance from the leaf tip to the start point for PX was greater for bundles later to mature. Thus, the pattern of distal start points in mature leaves reflected the progression of PX maturation from the midrib to bundles of lower rank. It is suggested that the involvement of more and more bundles in PX maturation as the leaf ages is a general occurrence in grass leaves, and that assessing how many bundles will have PX requires observations late in leaf development.

Effect of light and gibberellic acid on chromosome endoreduplication in leaf epidermis ofTriticum durum Desf.

The first foliage leaf ofTriticum durum Desf., cvs. Capelli and Creso, was studied for the action of light and gibberellic acid on different aspects of plant growth. Creso is a short-strawed cultivar carrying theRht 1 gene, that influences both plant height and sensitivity to applied gibberellins. In this study, a cytophotometric analysis of chromosome endoreduplication in bulliform cells of the leaf epidermis was undertaken. The bulliform cells are arranged in long rows and comprise 4C, 8C, and 16C cells. The relative percentage of these cells was recorded under different light regimes and in the presence or absence of gibberellic acid (GA3). Our data indicate that light strongly affects the occurrence of chromosome endoreduplication. Although cvs. Cappelli and Creso show the same frequency of endo-reduplicated cells in the dark, all light treatments induce lower endo-polyploidy in cv. Creso whereas, in cv. Cappelli, a reduction in endo-polyploidy is observed when plants are irradiated with blue-lacking lights. This indicates that the action of a blue-light responsive photo-receptor determines high endopolyploidy. With respect to GA3 treatment, cv. Creso is again shown to be insensitive to hormone application, whereas in cv. Cappelli, gibberellic acid influences endopolyploidy level in the dark, causing very high frequencies of 8C cells and relatively high frequencies of 16C cells.

Characteristics of Rooting and Leaf Emergence Rate, Early Growth and Heading Date of Rice Seedlings with Different Plant Age in Leaf Number.

Eleven kinds of rice seedlings with different plant age in leaf unmber in the range 0-7.2 (counting the incomplete leaf as the first leaf), raised under the same condition, were grown in the phytotron-controlled day/night temperature (25/20 or 20/15°C) with natural light to clarify the characteristics of rooting and leaf emergence rate after transplanting, and also the difference of earfy growth and heading date. Both the number of new roots and total new root length at 7 days after transplanting (TP) were higher in the seedlings with more leaves due to the nodal position of emerged new roots. The reverse relation was observed in the leaf emergence rate during that period due to the difference in average leaf blade length. Transplanting injury, indicated by the leaf emergence rate during 3 days after TP, increased in proportion to the number of leaves of the seedling, and was not observed in the youngest seedling without foliage leaf. The number of new roots showed a highly significant negative or positive correlation with leaf emergence rate or leaf elongation rate from the leaf sheath, respectively. Each of the growth parameters at 21 days after TP was superior in proportion to the number of leaves of seedlings, but the difference of each parameter among the seedlings decreased in order of: (1) plant length and age in leaf number, (2) number of tillers and roots, and (3) dry weight over time after TP due to the faster growth rate of seedlings with fewer leaves. Although the number of leaves on the main culm was almost the same among the seedlings (range 15.6-16.5), the dates of flag leaf emergence and heading were delayed proportionally in the seedlings with fewer leaves.

Behavior of organelles and their nucleoids in the shoot apical meristem during leaf development in Arabidopsis thaliana L.

The behavior of organelle nucleoids and cell nuclei was studied in the shoot apical meristem and developing first foliage leaves of Arabidopsis thaliana. Samples were embedded in Technovit 7100 resin, cut into thin sections and stained with 4′-6-diamidino-2-phenylindole to observe DNA. Fluorimetry was performed using a video-intensified microscope photon-counting system. The DNA content of individual mitochondria was more than 1 Mbp in the shoot apical meristem and the young leaf primordium, and decreased to approximately 170 kbp in the mature foliage leaf. In contrast, the DNA content of individual plastids was low in the shoot apical meristem and increased until day 7 after sowing. Application of 5-bromo-2′-deoxyuridine, an analogue of thymidine, was usesd to investigate DNA synthesis in situ. The activities of DNA synthesis in the mitochondria and plastids changed according to the stage of development. Mitochondrial DNA was actively synthesized in the shoot apical meristem and young leaf primordia. This strongly suggests that the amount of mitochondrial DNA per mitochondrion, which has been synthesized in the shoot apical meristem and young leaf primordium, is gradually reduced due to continual divisions of the mitochondria during low levels of mitochondrial DNA synthesis. Synthesis of DNA in the plastid became active in the leaf primordia following DNA synthesis in the mitochondria, and the small plastids were filled with large plastid nucleotids. This enlargement of the plastid nucleoids occurred before the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase and the development of thylakoids.

MARCO- AND MICROMORPHOLOGY OF CRINUM MOOREI VAR. SCHMIDTII, HOOK F. CULTIVATED IN EGYPT. PART 1: ROOT, BULB (fleshy scale leaves) and foliage leaf

MARCO- AND MICROMORPHOLOGY OF CRINUM MOOREI VAR. SCHMIDTII, HOOK F. CULTIVATED IN EGYPT. PART 1: ROOT, BULB (fleshy scale leaves) and foliage leaf