Leaf epidermal studies of four species of Chlorophytum Ker- Gawl in Nigeria

Studies of the foliar epidermal morphology in four species of Chlorophytum; C. orchidastrum, C. bichetii, C. stenopetalum and C. macrophyllum revealed the presence of stomata on both sides of the leaves (amphistomatic stomata distribution). In C. orchidastrum, few stomata are present on the adaxial surfaces. Stomata type has no diagnostic importance as all the species studied have tetracytic stomata. Stomata index (<10%) on the adaxial surface in C. orchidastrum easily distinguished the species from others. In C. bichetii and C. macrophyllum stomata index (<50%) was recorded while stomata index (>50%) was recorded for C. stenopetalum on the adaxial surface. Stomata index on the abaxial surface also shows that fewer stomata occur in C. macrophyllum compared with C. stenopetalum. The studies also revealed smooth leaf margin for C. orchidastrum. Papillea out growth were observed on the leaf margin of C. stenopetalum and C. macrophyllum, Papillea projections were however more pronounced in C. bichetii. Leaf epidermal character is hereby indicated as an important tool in delimiting species in the genus Chlorophytum. Keywords: Chlorophytum, stomata, epidermal cells, anatomy, foliar morphology.

Foliar epidermis morphology in Quercus (subgenus Quercus, section Quercus) in Iran

Foliar epidermis morphology inQuercus(subgenusQuercus, sectionQuercus) in IranThe foliar morphology of trichomes, epicuticular waxes and stomata inQuercus cedrorum, Q. infectoriasubsp.boissieri, Q. komarovii, Q. longipes, Q. macranthera, Q. petraeasubsp.ibericaandQ. robursubsp.pedunculiflorawere studied by scanning electron microscopy. The trichomes are mainly present on abaxial leaf surface in most species, but rarely they appear on adaxial surface. Five trichome types are identified as simple uniseriate, bulbous, solitary, fasciculate and stellate. The stomata of all studied species are of the anomocytic type, raised on the epidermis. The stomata rim may or may not be covered with epicuticular. The epicuticular waxes are mostly of the crystalloid type but smooth layer wax is observed inQ. robursubsp.pedunculiflora.Statistical analysis revealed foliar micromorphological features as been diagnostic characters inQuercus.

Effect of salt stress on nutrient concentration, photosynthetic pigments, proline and foliar morphology of Salvinia auriculata Aubl.

AIM: This study aimed to investigate the effects of NaCI and Na2So4 salts on Ca, CI, K, Mg N, P, S and Na content as well as on the content of photosynthetic pigments (chlorophyll-a, chlorophyll-b and carotenoids), proline content and on the foliar morphology of Salvinia auriculata Aubl. METHODS: The plants were collected in Jacu lagoon, located in the North of Rio de Janeiro State, and after a five-day-acclimation period, experiments were performed in the greenhouse with 0, 100, 200 mM concentrations of NaCI and Na2SO4 salts and the usual techniques for light and electron microscopy. RESULTS: After seven days of experiment, a decrease in the content of Ca2+, K+, Mg2+, P, N ions as well as in the content of photosynthetic pigments (chlorophyll-a,b and carotenoids) in Salvinia auriculata under saline treatments was observed. The proline content showed an upward tendency as compared to the control. Under transmission electron microscopy, it was observed that, on the foliar limb, there was a membrane system disorder, mainly of chloroplasts, with higher presence of starch grains of plant cells subjected to salinity. Under scanning electron microscope, the integrity of trichomes and foliar limb cells of Salvinia auriculata subjected to the control treatment as well as the changes caused by salinization on the surface of cells were observed. CONCLUSION: As for all the salinization effects evaluated, it was noticed that the increase in Na2SO4 salt concentration resulted in higher morphological and nutritional alterations in the floating aquatic macrophyte, Salvinia auriculata.

Susceptibility of Basil Cultivars and Breeding Lines to Downy Mildew (Peronospora belbahrii)

Downy mildew, caused by Peronospora belbahrii, is a new disease of basil (Ocimum spp.) in the United States. In 2009, different basil species, cultivars, and advanced breeding lines of sweet basil (30 in total) were evaluated for susceptibility to basil downy mildew in field trials in southern and northern New Jersey. Popular commercial sweet basil cultivars such as Martina, Nufar, and Poppy Joe were among the most susceptible to downy mildew. Symptoms and sporulation of P. belhahrii on Ocimum ×citriodorum and O. americanum cultivars were present but far less than on most O. basilicum cultivars evaluated. The cultivars Spice, Blue Spice, and Blue Spice Fil were the least susceptible to basil downy mildew with no visible symptoms. Similar results were observed in both field trials. This is the first report of potential resistance in Ocimum spp. to basil downy mildew. Observations from this study show that the development of resistant cultivars may be possible. Selection criteria such as foliar morphology, plant architecture as well as the presence of secondary metabolites are being examined as potential traits for developing downy mildew resistant basil cultivars.

Ecological Wood Anatomy of Miconia Sellowiana (Melastomataceae) in three vegetation types of paraná state, Brazil

Miconia sellowiana (Melastomataceae), a widespread species occurring in Araucaria Forest, Montane Dense Forest and Upper Montane Forest (Paraná state, Brazil) has a highly variable foliar morphology. This study investigated whether the wood anatomy follows this pattern influenced by environmental conditions. Samples of six individuals per area were collected, fixed and prepared, according to standard techniques in wood anatomy. ANOVA indicated differences for length and diameter of vessel elements and fibres, fibre wall thickness, width of rays and ray frequency, especially regarding the population of the Upper Montane Forest. The secondary xylem from this vegetation is characterized by shorter vessel elements and fibres, thicker fibre walls and wider rays. These characteristics are associated to a certain degree of water stress imposed to the plants in the Upper Montane Forest, mainly due to the shallow neosol soils. The Araucaria Forest and the Montane Dense Forest have more similar environmental conditions, supported by the Cluster analysis. The Principal Components Analysis explained 98% of the total variance, where fibre and vessel element lengths showed a posi-tive correlation; however, this analysis did not allow the separation of three distinct groups. Although less pronounced, the wood anatomical differences corroborate the results obtained with foliar morphology, where leaves from the Upper Montane Forest presented the most xeric characteristics among the populations of Miconia sellowiana studied.

Vertical gradients and tree-to-tree variation in shoot morphology and foliar nitrogen in an old-growth Pinus strobus stand

Acclimation to ambient light has been assumed to be the principal cause of vertical gradients in leaf nitrogen, foliar morphology, and related traits in forest canopies. We examined the relative role of crown exposure, damage, and reproduction as correlates of vertical gradients in shoot and needle morphology, anatomy, and chemistry in a ~120-year-old stand of Pinus strobus L. (eastern white pine) in central Ontario. Internodes at the top of trees were longer, wider, and produced more fascicles, but had lower fascicle survivorship than lower-canopy shoots. Needles on upper-canopy shoots also had higher allocation to resin ducts than mid- or lower-canopy needles, contained less nitrogen on a mass basis, and showed a higher leaf mass per area, C/N ratio, and chlorophyll a/b ratio. Tree-to-tree variation among the 26 trees measured traits was high, owing, in part, to differences in crown damage and reproductive status. Crown damage was associated with reduced leaf mass per area and other traits associated with shade acclimation, while high cone production was associated with reduced leaf nitrogen and chlorophyll in the upper canopy. Our results suggest that factors other than light acclimation play an important role in determining vertical gradients in foliar morphology, nitrogen, and leaf production in forest canopies.