Diversity in leaf anatomy, and stomatal distribution and conductance, between salt marsh and freshwater species in the C\u3csub\u3e4\u3c/sub\u3e genus Spartina (Poaceae)

Leaf anatomy, stomatal density, and leaf conductance were studied in 10 species of Spartina (Poaceae) from low versus high salt marsh, and freshwater habitats. • Internal structure, external morphology, cuticle structure, and stomatal densities were studied with light and electron microscopy. Functional significance of leaf structure was examined by measures of CO2 uptake and stomatal distributions. • All species have Kranz anatomy and C 4 δ13C values. Freshwater species have thin leaves with small ridges on adaxial sides and stomata on both adaxial and abaxial sides. By contrast, salt marsh species have thick leaves with very pronounced ridges on the adaxial side and stomata located almost exclusively on adaxial leaf surfaces. Salt marsh species also have a thicker cuticle on the abaxial than on the adaxial side of leaves, and CO2 uptake during photosynthesis is restricted to the adaxial leaf surface. • Salt marsh species are adapted to controlling water loss by having stomata in leaf furrows on the adaxial side, which increases the boundary layer, and by having large leaf ridges that fit together as the leaf rolls during water stress. Differences in structural-functional features of photosynthesis in Spartina species are suggested to be related to adaptations to saline environments

Long-term performance of a plant microbial fuel cell with Spartina anglica

The plant microbial fuel cell is a sustainable and renewable way of electricity production. The plant is integrated in the anode of the microbial fuel cell which consists of a bed of graphite granules. In the anode, organic compounds deposited by plant roots are oxidized by electrochemically active bacteria. In this research, salt marsh species Spartina anglica generated current for up to 119 days in a plant microbial fuel cell. Maximum power production was 100 mW m−2 geometric anode area, highest reported power output for a plant microbial fuel cell. Cathode overpotential was the main potential loss in the period of oxygen reduction due to slow oxygen reduction kinetics at the cathode. Ferricyanide reduction improved the kinetics at the cathode and increased current generation with a maximum of 254%. In the period of ferricyanide reduction, the main potential loss was transport loss. This research shows potential application of microbial fuel cell technology in salt marshes for bio-energy production with the plant microbial fuel cell

Effects of Nutrition During Gilt Development on Lifetime Productivity of Sows of Two Prolific Maternal Lines: Growth and Puberty Characteristics of Rep 1 Gilts

This report is an annual update of an ongoing experiment initiated in 2005 to investigate effects of energy restriction during gilt development on reproduction through four parities. Gilts of two genetic lines expected to differ in rate of growth are used and are developed with either ad libitum access to feed or are restricted in energy to 75% of ad libitum amounts from approximately 120 days of age to breeding. Semen of the same sires, an industry maternal line, was used to produce gilts of both lines, but their dams were from two uniquely different populations. Dams of one line were an industry Large White x Landrace (LW x LR) cross and dams of the other line were from a Nebraska line (Line 45) selected 23 generations for increased ovulation rate, uterine capacity, and litter size (L45X). Both lines are expected to be prolific, but L45X females are expected to be extra prolific, being earlier maturing and having larger litters; whereas LW x LR gilts are expected to have greater rates of lean growth. The experiment is being conducted in three replications with 160 gilts per replication. Replication 1 gilts completed the gilt development phase in summer of 2005 and were mated for December 2005 litters. Replication 2 gilts were born in May 2005 and are currently in the gilt development phase. Replication 3 gilts will be born in November 2005. The project will terminate when Replication 3 females wean their fourth parity litters. This report summarizes growth rate, backfat and longissimus muscle deposition, and age at puberty in Replication 1 gilts. Lines differed in growth rate, LW x LR cross gilts grew faster than L45X gilts, but at the same weights, lines had similar backfat and longissimus muscle area. L45X gilts were younger at puberty. Restricting intake during the gilt development period affected both lines similarly, reducing growth rate and backfat deposition, but did not affect longissimus muscle deposition. The objectives of the experiment are being accomplished and will answer the question of whether energy restriction during gilt development, and thus less backfat at breeding, affects lifetime productivity