Todd P. Egan

The Effects of Temperature and Seasonal Change on the Germination of Two Salt Marsh Species, Atriplex prostrata and Salicornia europaea, along a Salinity Gradient

The purpose of this study was to determine whether seasonal temperature changes interact with salinity concentration to inhibit germination. Flooding of a marsh may also influence the size of the seed bank. Soil cores (6.0 cm \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Population studies of Limonium stocksii (Plumbaginacea) from a salt desert near the arabian sea coast

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Effects of accelerated ageing on germination and biochemistry of eight rice cultivars

\end{document} cm deep) were collected from four salt marsh zones in Rittman, Ohio. Salt was most concentrated at the innermost zone, which contained almost exclusively Salicornia europaea, and least concentrated at the outermost zone, which contained mainly Hordeum jubatum and Atriplex prostrata. Soil cores were collected during April, June, and October 1996 and were placed in temperature treatments of 5°/15°C, 5°/25°C, 15°/25°C, and 25°/35°C (dark/light). Seeds were germinated for 8–10 wk, and the seeds that did not germinate were counted from a 2.2‐cm‐diameter subsample. Results demonstrated that for both S. europaea and A. prostrata, the total number of seeds that germinated decreased throughout the growing season. The number of ungerminated seeds decreased throughout the year for A. prostrata, but for S. europaea, the number of ungerminated seeds increased from April to June and then decreased from June to October. For both species, the ratio of germinated to total seeds decreased from April to June and increased from June to October. Over the growing season and in all salinity zones, the 5°/25°C temperature treatment was the most stimulatory to seed germination. We suspect that a flooding event in June that killed the standing vegetation may have reduced soil salinity and allowed more seeds than usual to germinate, thus effectively eliminating the S. europaea seed bank. Thus, seed banks play a significant role in these salt marsh habitats by providing a new source of seeds for the establishment of later cohorts after flooding or salt stress eliminates an early cohort of seedlings.

The Seed Bank of a Hypersaline Shrub Community in the Bahamas

Salicornia europaea L. is a halophyte that often occupies the lowestand most saline (>3.5% total salt) areas of salt marshes. Atriplexprostrata Boucher is less salt tolerant than S. europaea and oftengrows in a less saline (<2.0% total salts) zone adjacent to S. europaea. The purpose of this experiment was to determine thecompetitive outcome when these two species are grown at differentsalinities to ascertain the extent salinity and competition affect plantzonation. Plants were grown in a de Wit replacement series at 85, 170,and 340 mM NaCl in half-strength Hoaglands no. 2 nutrient solution fortwo months. There was a significant effect of salt concentration,competition, and their interaction on biomass production of S. europaea plants. However, only salt concentration significantly affectedbiomass production of A. prostrata plants. Results of thisexperiment confirmed the results of other studies that demonstrated thatthe more salt tolerant species were less competitive at lower salinities. Atriplex prostrata was the better competitor at 85 mM NaCl, whereasS. europaea was the better competitor at 340 mM NaClbecause growth of A. prostrata was inhibited. At 170 mMNaCl, A. prostrata biomass production decreased more than S. europaea biomass in mixed culture.

Effects of a super absorbent polymer on soil properties and plant growth for use in land reclamation

Abstract A population of Limonium stocksii was studied for one year at the upper end of Manora Creek along the Arabian Sea coast, near Karachi, Pakistan. The community was divided into three zones. Soil pH varied from 8.1 to 8.5. Soil conductivity was highest (191 dS m−1) in September and lowest (55 dS m−1) in June. Soil water content was relatively low and varied from 1.6% in February to 9.5% in June. Limonium stocksii maintained a persistent seed bank, which peaked at 5,887 seeds m−2 in May. Very slow growth was observed; however, plants in the intermediate zone showed better growth than the other two zones. Stem and leaf tissue water content were affected by salinity fluctuations, but root tissue water remained unaffected. Sodium (Na+) and chloride (Cl−) accumulated in stems and leaves more than other ions. Leaves also accumulated a very high amount of magnesium (Mg++) compared to roots and stems.

Organic and urea nitrogen fertilizer effects on rapeseed and wild mustard competition

ABSTRACT Oil cultivars of Brassica napus L. were grown to compare the effects of composted municipal waste (CMW) and sheep manure (SM) to field soil (C0). To each soil group, one of three levels of urea nitrogen fertilizer (N) was added. SM grown plants had higher N than those grown in CMW with the Sarigol cultivar having a higher N content than the RGS cultivar. Field soil plants grown in control soil had lowest N levels. Organic amendments increased N content of both cultivars. SM grown plants produced more siliques, a higher seed yield, and greater 100 seed weight compared to those grown in CMW. Control soil plants had the lowest number of siliques, seed yield, and 100 seed weight. CMW-treated plants contained slightly more metals than SM plants. Field soil plants had the lowest metal levels. CMW and SM application had potential to improve the growth and chemical composition without adding urea.

Effects of Urea Nitrogen and Residual Composted Municipal Waste and Sheep Manure on the Growth and Chemical Composition of Two Triticale Genotypes

ABSTRACT Rice seed deterioration rate due to aging is correlated with ambient temperature, relative humidity, and moisture. Eight cultivars were analyzed for differences in seed deterioration via accelerated ageing at 45°C and 100% relative humidity (RH) for 24, 48, 72, 96, 120 hr. Khazar and Neda had highest germination percentages when exposed to 120 hr seed ageing. For Lenjan, with increased seed ageing, moisture content increased from 9.8% in the control to 21.7% after the 120 hr treatment. Khazar and Shiroudi had the lowest decrease in shoot length. Root length decreased from 0 hr control to 120 hr treatment, and was lowest in Fajr and Khazar. Minimum electrical conductivity was observed in Neda and Fajr after 120 hr. Lowest increases in lipid peroxidation from control to 120 hr treatment was in Fajr, Khazar, and Neda. Neda and Khazar are the most suitable cultivars to store in the humid, sub-tropics of northern Iran.

Factors Affecting Buttonwood (Conocarpus erectus L.) Germination

Along the Fresh Lake causeway on San Salvador Island, the Bahamas, the seed bank was compared to the above ground vegetation in May 2006. Vegetation was dominated by a shrub canopy of Conocarpus erectus. A 49 m transect was run along the south side of the Fresh Lake causeway, and 10 secondary transects were randomly run from it towards Fresh Lake. Percent above ground cover was determined, and soil cores were taken along secondary transects at 0, 1, and 2 m. Percent above ground cover was calculated in 15 × 15 cm quadrats, and 6.0 cm diameter × 7.5 cm deep soil samples (n = 30) were collected. Species diversity was low, with only Borrichia arborescens (1.7 %), Sporobolus virginicus (16.8 %) and a member of the Poaceae (<1 %) representing aboveground vegetation. Only Conocarpus erectus represented the canopy. The majority of each quadrat along the secondary transects was bare ground. Percent above ground vegetation along the transects was determined and compared to number of seeds present. Only 43 (15,208 seeds/m2) Conocarpus erectus seeds were present in the entire seed bank, and were found at plots 2, 8, and 10. Shrubs of this species were found at plots 1, 2, 7, and 10. No seeds of any other species were found in any transect. Tidal action may be the main force in distributing seeds along the causeway and out of the sampled area. A second factor accounting for low seed numbers may have been that seeds germinated but seedlings died before being recruited into the canopy.