Nitrogen deficiency effects on plant growth, leaf photosynthesis, and hyperspectral reflectance properties of sorghum

An experiment was conducted under outdoor pot-culture conditions to determine effects of nitrogen (N) deficiency on sorghum growth, physiology, and leaf hyperspectral reflectance properties. Sorghum (cv. DK 44C) was seeded in 360 twelve-litre pots filled with fine sand. All pots were irrigated with half-strength Hoagland's nutrient solution from emergence to 25 days after sowing (DAS). Thereafter, pots were separated into three identical groups and the following treatments were initiated: (1) the control (100% N) continued receiving the half-strength nutrient solution; (2) reduced N to 20% of the control (20% N); and (3) withheld N from the solution (0% N). Photosynthetic rate (Pn), chlorophyll (Chl) and N concentrations, and hyperspectral reflectance of the uppermost, fully expanded leaves were determined at 3- to 4-day-interval from 21 to 58 DAS during the N treatments. Plants were harvested 58 DAS to determine effects of N deficiency on leaf area (LA), biomass accumulation, and partitioning. Nitrogen deficiency significantly reduced LA, leaf Chl content and Pn, resulting in lower biomass production. Decreased leaf Pn due to N deficiency was mainly associated with lower stomatal conductance rather than carboxylation capacity of leaf chemistry. Among plant components of dry weights, leaf dry weight had the greatest and root dry weight had the smallest decrease under N deficiency. Nitrogen-deficit stress mainly increased leaf reflectance at 555 (R₅₅₅) and 715 nm (R₇₁₅) and caused a red-edge shift to shorter wavelength. Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R₄₀₅/R₇₁₅ (r² = 0.68^***) and R₁₀₇₅/R₇₃₅ (r² = 0.64^***), respectively, but also the first derivatives of the reflectance (dR/dλ) in red edge centered 730 or 740 nm (r² = 0.73–0.82^***). These specific reflectance ratios or dR/dλ may be used for rapid and non-destructive estimation of sorghum leaf Chl and plant N status.     

Fine structure of a new mycophagous amoeba and its feeding on Cochliobolus sativus

An unidentified mycophagous soil amoeba is described. The pigmented soil-borne fungus Cochliobolus sativus and four other fungal species, both pigmented and hyaline, were utilized as food. Spores were ingested and lysed within digestive vacuoles by general wall erosion. This contrasts with the wall perforation mechanism described for other mycophagous amoebae. Ultrastructural studies of trophozoites showed that large quantities of electron dense granules were released into the digestive vacuoles during fungal cell lysis. These were incorporated into the amoebal protoplast. Bacteria were commonly present in the amoebal protoplasts and within digestive vacuoles. Their possible role as endosymbionts is discussed.     

Soil amoebae and saprophytic survival of Gaeumannomyces graminis tritici in a suppressive pasture soil

Hyphae of Gaeumannomyces graminis var. trilici deposited on millipore niters were buried in a naturally-suppressive permanent pasture soil and in a non-suppressive wheat-field soil. Hyphal density and survival of pigmented hyphae declined at a faster rate in the pasture soil than in the wheat-field soil. Hyphae recovered from the suppressive soil showed a higher association of mycophagous and other soil amoebae and scanning electron microscopy of these hyphae showed extensive erosion and discrete perforations in their walls. The possible role of soil amoebae in reducing saprophytic survival of the take-all fungus is discussed.     

Glyphosate applied preharvest induces shikimic acid accumulation in hard red spring wheat (Triticum aestivum)

Glyphosate is a nonselective herbicide used as a harvest aid in a variety of crops. Glyphosate is absorbed into the foliage and translocated to metabolically active regions in the plant where it interferes with the shikimic acid pathway. Experiments were conducted to determine the accumulation and distribution of shikimic acid in wheat treated with glyphosate at soft and hard dough stages of kernel development and to determine the fate of shikimic acid during milling and bread making. Elevated levels of shikimic acid were detected throughout the wheat plant. Shikimic acid concentrations peaked 3-7 days after treatment and then declined until harvest. Shikimic acid content was 3-fold greater in flour and 2-fold greater in the bread derived from treated wheat than nontreated wheat. Similarly, elevated levels of shikimic acid were found in the crumbs and crust of bread made with flour from glyphosate treated wheat. Glyphosate applied preharvest resulted in shikimic acid accumulation in hard red spring wheat and subsequent end-use products.     

A cluster of metabolic defects caused by mutation in a mitochondrial tRNA

Hypertension and dyslipidemia are risk factors for atherosclerosis and occur together more often than expected by chance. Although this clustering suggests shared causation, unifying factors remain unknown. We describe a large kindred with a syndrome including hypertension, hypercholesterolemia, and hypomagnesemia. Each phenotype is transmitted on the maternal lineage with a pattern indicating mitochondrial inheritance. Analysis of the mitochondrial genome of the maternal lineage identified a homoplasmic mutation substituting cytidine for uridine immediately 5' to the mitochondrial transfer RNA(Ile) anticodon. Uridine at this position is nearly invariate among transfer RNAs because of its role in stabilizing the anticodon loop. Given the known loss of mitochondrial function with aging, these findings may have implications for the common clustering of these metabolic disorders.     

Cardiac myosin activation: a potential therapeutic approach for systolic heart failure

Decreased cardiac contractility is a central feature of systolic heart failure. Existing drugs increase cardiac contractility indirectly through signaling cascades but are limited by their mechanism-related adverse effects. To avoid these limitations, we previously developed omecamtiv mecarbil, a small-molecule, direct activator of cardiac myosin. Here, we show that it binds to the myosin catalytic domain and operates by an allosteric mechanism to increase the transition rate of myosin into the strongly actin-bound force-generating state. Paradoxically, it inhibits adenosine 5'-triphosphate turnover in the absence of actin, which suggests that it stabilizes an actin-bound conformation of myosin. In animal models, omecamtiv mecarbil increases cardiac function by increasing the duration of ejection without changing the rates of contraction. Cardiac myosin activation may provide a new therapeutic approach for systolic heart failure.     

Improving Lettuce Yield and Quality of an Agricultural Soil Using a Combination of Arbuscular Mycorrhizal Fungus and Phosphate-Green Wastes Compost

The use of biofertilizers on agricultural soils could act positively to improve soil fertility and crop productivity. This work was performed to assess the potential beneficial impacts of local produced phospho-compost and/or an exogenous arbuscular mycorrhizal fungus (AMF) (Rhizoglomus irregulare DAOM 197198) on lettuce agro-physiological and soil characteristics under filed conditions. Four treatments were applied: control treatment without any biofertilizer, compost, AMF, and compost?+?AMF treatments. Obtained results showed that shoot nitrogen (N) and phosphorus (P) were significantly improved in lettuce plants treated with compost supplementation and/or AMF inoculation compared to the control with a maximum increment for P in plants treated with compost (106%). As for growth traits, lettuce plants treated with compost?+?AMF recorded the highest values in terms of shoot and root dry weights and yield by 121, 54 and 127%, respectively, compared to the control plants. Considering physiological and biochemical traits, stomatal conductance, and chlorophyll fluorescence as well leaf area index and total soluble sugar and protein concentration were significantly improved in plants treated with compost and/or AMF compared to the control. In addition, soil properties, especially the soil total organic carbon, N, P, and glomalin-related soil protein content were significantly enhanced after two months of field experiment in treated soils with the applied biofertilizers alone or in combination compared to the control. Based on the main obtained results, applied biofertilizers were able to increase lettuce productivity and soil fertility under field conditions, especially the compost?+?AMF treatment, which demonstrated an effectiveness promotion of lettuce productivity and soil fertility.

     

Stormwater quality improvement potential of an urbanised catchment using water sensitive retrofits into public parks

Urban stormwater management is undergoing a transition from centralised hydrologically efficient systems to collections of dispersed, multi-functional elements. In response to a better understanding of impervious surface areas, the adoption of water sensitive urban design is promising for new large urban developments. However, spatial and economic constraints prohibit its adoption in established urban areas. We explore the potential for improvement to stormwater quality if 10% of existing parks in an established urban catchment are reserved for stormwater filtration. Spatially explicit hydrologic modelling is used to model the effects of parks in an existing urban catchment in South Australia as networks of bioretention devices. The allocation of 10% of parks that cover less than 16% of the landscape for bioretention devices may result in a 62% reduction (7.8 tonnes per year) of nitrogen from stormwater. The sources and destinations of stormwater pollutants are mapped to explore the strength and weaknesses of park size and distribution within each sub-catchment. Large parks situated lower in the catchment along the main trunk, and distributed smaller parks higher along the secondary stormwater network are shown to be effectively located. The potential for increasing the utilitarian value of many public parks by demonstrating the capacity for significantly improving urban stormwater quality is illustrated in this exploratory model. Opportunities for targeted improvements to stormwater quality are examined in the discussion.     

An ethnobotanical survey of medicinal plants used by ethnic people in West and South district of Tripura,India

An ethno-medicinal investigation was conducted to highlights the traditional knowledge of medicinal plants being used by the tribe in West and South district of Tripura. This paper provides information about the different uses of plants used in their primary health care system. Tripura is a small north-eastern state of India and also a part of both Himalayan and Indo-Burma biodiversity region. It is a goldmine of medicinal plants and use of different plants in tribal traditional heath care systems has long history. Nineteen different tribes in Tripura, depend on natural resources at a great extent. This paper documented 113 medicinal plant species from 56 families along with their botanical name, local name, family name, habit, medicinal parts used, and traditional usage of application. The dominant families are Euphorbiaceae (7 species), Apocynaceae (6 species), Fabaceae and Rubiaceae (5 species each), Caesalpiniaceae, Asteraceae, Liliaceae and Verbenaceae (4 species each), Combretaceae, Labiatae, Malvaceae, Rutaceae and Zingiberaceae (3 species each). Tribes of Tripura have rich traditional knowledge on plant based medicine. Different parts of the plants in crude form/plant extracts/decoctions/infusion or pastes are employed in diverse veterinary and human diseases by the tribe’s of Tripura in daily life.     

��Observations on Aerosol Optical Depth Over a Period of 3 Years at Kaikhali (22.022��N, 88.614��E) Inside a Special Mangrove Ecosystem��The Sundarbans��

The paper reports the observations of the aerosol studies carried-out for three years (2004-2007) during the summers and winters at Kaikhali (22.0220 N & 88.6140E) lying in the east coast of India inside a special mangrove ecosystem: 'The Sundarbans'. Aerosol optical depths were measured using a five filter channel sunphotometer with wavelengths at 340, 500,870, 936 and 1020 nm respectively. The sampling site enjoys a tropical climate and is under the strong influence of the southwest or summer monsoon and weak northeast or winter monsoon. The mean aerosol optical depth (AOD) during the winters (2004-2007) for the filter channels 340, 500, 870, 936 and 1020 nm have been found to be 1.478, 1.014, 0.579, 0.541 and 0.523 respectively whereas for the summer periods, they have been found to be 1.173, 0.859, 0.603, 0.564 and 0.597 respectively. The mean values of the angstrom exponent calculated for the winter and summer months over the years 2004-2007 have been found to be 1.283, 0.999, 1.285 and 1.094, 1.167 and 1.91 respectively. Generally the higher angstrom exponent values during the winter periods over the years from 2004-2007 except for the year 2005-2006 indicate high ratio of smaller fractions to larger fractions. The values of Angstrom exponents observed at the site suggest that the aerosol comprise mostly of the small size particles. An attempt has been made in the paper to compare the aerosol optical depth and angstrom exponent values with another study conducted in a different coastal zone in India.