KEANEKARAGAMAN TUMBUHAN LUMUT (BRYOPHYTA) PADA BERBAGAI KETINGGIAN HUBUNGANNYA DENGAN KONDISI LINGKUNGAN DI WILAYAH LERENG SELATAN MERAPI PASCA ERUPSI

Penelitian ini bertujuan untuk mengetahui jenis-jenis tumbuhan lumut, indeks keanekaragaman tumbuhan lumut, keanekaragaman jenis tumbuhan lumut, serta hubungan kondisi lingkungan yang meliputi faktor klimatik (intensitas cahaya, suhu udara, kelembaban udara) dan faktor edafik (suhu tanah, kelembaban tanah, pH tanah) dengan keanekaragaman jenis tumbuhan lumut diwilayah lereng selatan Merapi pasca erupsi. Penelitian ini merupakan penelitian dengan metode observasi dan hasilnya dianalisis secara deskriptif. Populasi penelitian adalah semua jenis lumut terrestrial pada berbagai ketinggian di wilayah lereng selatan Merapi pasca erupsi. Sampel penelitian ini adalah semua tumbuhan lumut terrestrial yang teramati di 30 plot pengamatan pada berbagai ketinggian sepanjang wilayah penelitian. Penelitian dilakukan dengan menentukan lokasi pengamatan dan menentukan batasan-batasan pada masing-masing ketinggian (1000 m dpl, 1200 m dpl dan 1400 m dpl). Mengambil sampel secara purposive sampling dengan membuat ukuran plot 1 x 1 m 2 dan melakukan pengukuran faktor lingkungan yaitu klimatik yang meliputi : Suhu udara, kelembaban udara, dan intensitas cahaya, dan untuk faktor edafik meliputi : Suhu tanah, kelembaban tanah, dan pH tanah. Kemudian melakukan identifikasi jenis tumbuhan lumut lalu menghitung luas penutupan setiap jenis pada tiap plot sekaligus perhitungan luas penutupan seluruh jenis pada masing-masing plot. Mencatat jenis tumbuhan pelindung pada plot yang diamati. Hasil penelitian dianalisis secara deskriptif dengan menentukan indeks keanekaragaman tumbuhan untuk menentukan keanekaragaman tumbuhan lumut di wilayah lereng selatan Merapi pasca erupsi. Hasil penelitian diperoleh bahwa ditemukan 11 jenis tumbuhan lumut terrestrial di lereng selatan Merapi pasca erupsi. Indeks keanekaragaman tumbuhan lumut pada ketinggian 1000 m dpl, 1200 m dpl, dan 1400 m dpl sebesar 0,810, 0,675 dan 0,471. Keanekaragaman tumbuhan lumut adalah rendah. Faktor klimatik pada berbagai ketinggian di wilayah lereng selatan Merapi pasca erupsi berpengaruh terhadap keanekaragaman jenis tumuhan lumut. Karena semakin tinggi tempat, intensitas cahaya semakin tinggi, suhu semakin tinggi, kelembaban semakin rendah. Maka keanekaragaman jenis tumbuhan lumut juga semakin rendah. Kata Kunci : Keanekaragaman jenis, Tumbuhan lumut (Bryophyta), Ketinggian

Differential sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides

Panicum schinzii (Transvaal millet), P. dichotomiflorum (Fall panicum) and P. capillare (Witchgrass) are alien panicoid grasses that have gradually spread and are now locally naturalized in corn fields in Belgium. One of the possible reasons for their expansion in corn fields might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HP-PD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two AILS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling populations of P. schinzii, P. dichotomiflorum and P. capillare (all naturalized Belgian populations except for P. capillare). In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive to tembotrione but moderately sensitive to topramezone and poorly sensitive to mesotrione and sulcotrione. However, P. dichotomiflorum was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized P. dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage)

Phosphoenolpyruvate Carboxykinase Assayed at Physiological Concentrations of Metal Ions Has a High Affinity for CO2

The effect of Mn2+/Mg2+ concentration on the activity of intact, homogeneous phosphoenolpyruvate carboxykinase (PEPCK) from leaves of the C4 grass, Guinea grass (Panicum maximum), have been investigated. Assay conditions were optimized so that PEPCK activity could be measured at concentrations of Mn2+/Mg2+ similar to those found in the cytosol (low micromolar Mn2+ and millimolar Mg2+). PEPCK activity was totally dependent on Mn2+ and was activated at low micromolar concentrations of Mn2+ by millimolar concentrations of Mg2+. Therefore, at physiological concentrations of Mn2+, PEPCK has a requirement for Mg2+. Assay at physiological concentrations of Mn2+/Mg2+ led to a marked decrease in its affinity for ATP and a 13-fold increase in its affinity for CO2. The Km (CO2) was further decreased by assay at physiological ATP to ADP ratios, reaching values as low as 20 μM CO2, comparable with the Km (CO2) of ribulose 1,5-bisphosphate carboxylase-oxygenase. This means that PEPCK will catalyze a reversible reaction and that it could operate as a carboxylase in vivo, a feature that could be particularly important in algal CO2-concentrating systems

Influence of Foliar Exposure, Adjuvants, and Rain-free Period on the Efficacy of Glyphosate for Torpedograss Control

The proportion of torpedograss tissue exposed to glyphosate at application rates of 0.28, 0.56, 1.12, 2.24, and 4.48 kg/ha affected control as measured by regrowth. The effect of tissue exposure was more pronounced as application rate decreased. This study suggests that higher rates of glyphosate need to be used during higher water levels, when less torpedograss tissue is exposed to herbicide spray and lower rates may be used during periods of low water levels. Addition of the water conditioning agent Quest (R) (0.25% v/v) to glyphosate spray mixtures diminished the influence of simulated rain events following glyphosate application. Twelve other adjuvants did not influence the effect of simulated rain events

Mapping and Distribution of Torpedograss and Evaluating the Effectiveness of Torpedograss Management Activities in Lake Okeechobee, Florida

Thousands of hectares of native plants and shallow open water habitat have been displaced in Lake Okeechobee’s marsh by the invasive exotic species torpedograss ( Panicum repens L.). The rate of torpedograss expansion, it’s areal distribution and the efficacy of herbicide treatments used to control torpedograss in the lake’s marsh were quantified using aerial color infra red (IR) photography.(PDF has 6 pages.

Beach impact study, Padre Island National Seashore

Prepared for Office of Natural Science, Southwest Region, National Park Service, under contract CX70005044830 April 1976Vegetative differences between heavily and very lightly trafficked beaches show that more beach traffic correlates with quantitative decreases in variety and density of plants and with declines of grasses relative to forbs. The vegetated portions of all beaches continue to grow in volume. However, this is at the expense of the more seaward (more trafficked) parts of the beaches and has lead to overall loss of total beach volume except where vehicular traffic is prohibited. The very lightly trafficked beach is the only study site wherein the entire beach to mean sea level has grown. The effect of these trends on resistance to storm surge erosion remains to be tested.Marine Scienc