Smoke alleviates adverse effects induced by stress on rice

Smoke and salinity are environmental hazards. Smoke produced DNA damage, inflammatory, and oxidative stress in humans while salinity reduced plant yield. However, smoke from plants is beneficial towards plant growth. In this study, smoke of two plants, Buhania varegata (1:1000 and 1:5000 dilutions (v/v)) and Cymbopogon jwarancusa (1:500 and 1:1000), were used to determine effects on different physiological and biochemical parameters in rice Basmati-385 (B-385) and Shaheen Basmati under different saline concentrations (control: 50, 100, and 150 mM). With increasing salinity, germination%, seedling growth, K⁺, Ca⁺, cell membrane stability, and total nitrogen and protein contents were decreased while Na⁺ content increased. However, seeds primed with different dilution of smoke significantly diminished the adverse effects of salinity and shown to produce positive responses in all of the above parameters. The most effective dilutions were 1:5000 for Buhania varegata and C-500 for Cymbopogon jwarancusa. It seems that priming with plant smoke solution is a potent stimulant for plant growth exerting a significant role in physiology and biochemistry of rice plants under saline condition.     

Association between plant species diversity and edaphic factors in the lower reaches of the Heihe River,northwestern China

The lower reaches of the Heihe River, in northwestern China, is characterised by unique local edaphic conditions that have influenced the development of local desert riparian forests. This study examines the variations in spatial variation patterns to reveal the relationships between plant species diversity and soil moisture/salinity/texture gradients at different soil depths, providing insights into the management and restoration of vegetation in ecosystems in the study area. The species–environmental relationships are investigated by redundancy analysis based on the plant species diversity matrix and the edaphic gradient matrix. A survey of 61 sampling plots identified 37 plant species in the study area. The distribution pattern of the plant species diversity are mainly affected by soil moisture, soil salinity, and soil texture at different soil depths. These edaphic factors are able to explain 98.47% of the total variation in the analysed vegetation dataset. Soil moisture, salinity, and texture content vary in terms of both the soil depths and the vegetation types in the study area. The plant community Class IV, xeric shrub, has the lowest soil water content among different vegetation types. The surface soil salinity differs for different plants and follows the order: Sophora alopecurides?>?Tamarix chinensis?>?Populus euphratica.     

Tolerance of Mediterranean seagrasses (<Emphasis Type="Italic">Posidonia oceanica</Emphasis> and <Emphasis Type="Italic">Cymodocea nodosa</Emphasis>) to hypersaline stress: water relations and osmolyte concentrations

The present study examines for the first time the effects of increased salinity on water relations and osmolyte (carbohydrates and amino acids) concentrations in two Mediterranean seagrass species, Posidonia oceanica and Cymodocea nodosa, which are adapted to growth in environments with contrasting salinity and have a known differential sensitivity to alterations in ambient salinity. The specific aim was to obtain insights into their respective capacities to cope with natural or anthropogenically induced (e.g. desalination plants) hypersaline stress and its ecological implications. To this end, large plant fragments of both seagrass species were maintained for 47 days in a laboratory mesocosm system under ambient salinity (37 psu; control) and three chronic hypersaline conditions (39, 41 and 43 psu). Analyses of leaf-tissue osmolality indicated that both species followed a dehydration avoidance strategy, decreasing their leaf water potential (Ψ_w) as the external salinity increased, but using different physiological mechanisms: whereas P. oceanica leaves exhibited a reduction in osmotic potential (Ψ_π), C. nodosa leaves maintained osmotic stability through a decrease in turgor pressure (Ψ_p) probably mediated through cell-hardening processes. Accordingly, the concentrations of soluble sugars and some amino acids (mainly Pro and Gly) suggested the activation of osmoregulatory processes in P. oceanica leaves, but not in C. nodosa leaves. Osmotic adjustments probably interfered with leaf growth and shoot survival of P. oceanica under hypersaline stress, whereas C. nodosa showed a more efficient physiological capacity to maintain plant performance under the same experimental conditions. These results are consistent with the more euryhaline ecological behaviour of C. nodosa and contribute to understanding the high vulnerability shown by P. oceanica to even mild increments in seawater salinity.     

Gene expression profiles of the swimming crab <Emphasis Type="Italic">Portunus trituberculatus</Emphasis> exposed to salinity stress

The swimming crab, Portunus trituberculatus, is an important marine fishery and aquaculture species. Although P. trituberculatus is a euryhaline species, water salinity condition influenced its distribution, migration route, and artificial propagations. To investigate gene expression in the P. trituberculatus exposed to different salinity stresses, 2426 expressed sequence tags (ESTs) from gill cDNA library were selected to spot on a cDNA microarray chip. In total, 417 differentially expressed genes were identified and grouped into eight clusters by hierarchical clustering analysis. Approximately 71.5% of grouped genes belonged to three independent expression patterns, indicating that these three expression patterns may represent three important stress tolerance pathways or networks in P. trituberculatus. Moreover, our cDNA microarray data suggested that there were differences in gene expression patterns of P. trituberculatus for low salinity and high salinity acclimation, suggesting that two salinity challenges resulted in a wide variation of gene expression in P. trituberculatus. In addition, a series of genes such as CCAAT/enhancer-binding protein, Na/K ATPase β-subunit, and heat shock proteins (HSPs) genes were suggested to be key elements during salinity acclimation process. Overall, this work represented an important step toward understanding the molecular processes and mechanisms involved in salinity acclimation of the swimming crab.     

Reclamation with phytoremediation of area affected by sewage sludge at the Thessaloniki Wastewater Treatment Plant in Sindos (Greece)

The present research focused on the experimental investigation of phytoreclamation of areas affected by sewage sludge disposal and improving the quality of the sludge. It was conducted in two stages: laboratory and pilot applications. This paper reports on the first stage, which tested, under greenhouse conditions, the possibility of using various species of plants cultivated in the sludge from the Thessaloniki Wastewater Treatment Plant (ThWWTP, Greece) with different amendments. The results of the 30-day experiment showed that the quality of the output sludge material varied significantly in comparison to the input sludge material. These variations were considered as positive, as the output sludge obtained texture and structure, aeration conditions were improved, and the content of some trace metals, excess nutrients (e.g., P), and salts (of Na) were reduced. These were all influenced by both the type of treatment and the plant species used. In conclusion, the best treatments, T1, T3, and T4 (soil/sludge mixture 70%/30%, soil/sludge/gravel mixture 50%/25%/25%, and soil/sludge/gravel mixture 45%/45%/10%, respectively), and the best suited plant species, Helianthus annuus L. and Zea mays L., were proposed to be used in the pilot application (in situ) at the site within the ThWWTP.     

Effects of salinity and possible interactions with temperature and pH on growth and photosynthesis of <Emphasis Type="Italic">Halophila johnsonii</Emphasis> Eiseman

The effects of salinity, temperature, and pH variations on growth, survival, and photosynthetic rates of the seagrass Halophila johnsonii Eiseman were examined. Growth and survival responses to salinity were characterized by aquarium experiments in which plants were exposed to seven different salinity treatments (0, 10, 20, 30, 40, 50, and 60 psu) during 15 days. Photosynthetic behavior was assessed for short-term salinity exposures (1 or 20 h) by incubation experiments in biological oxygen demand (BOD) bottles and by measuring photosynthesis versus irradiance (PI) responses in an oxygen electrode chamber. In the bottle experiments the possible effects of interactions between salinity and temperature (15, 25, and 35°C) or pH (5, 6, 7, and 8.2) were also examined. Growth and survival of H. johnsonii were significantly affected by salinity, with maximum rates obtained at 30 psu. Salinity also altered the parameters of the PI curves. Light-saturated photosynthesis (P _max) and the photosynthetic efficiency at subsaturating light (α) increased significantly up to an optimum of 40 psu, decreasing again at the highest salinities. Dark respiration rates and compensating irradiance (I _c) showed minimum values at 40 and 50 psu, while light-saturation point (I _k) was maximum at 30–50 psu. An interaction between salinity and temperature was not found although an increase of temperature alone produced an increase in α, P _max, respiration rates, and I _k. An interaction between salinity and pH was only found in the P _max response: P _max increased with pH=5 at 30 psu. In addition, reducing the pH increased α significantly. In the BOD bottles experiment a significant reduction in the dark respiration with decreasing pH was observed, but the opposite trend was observed in the photosynthetic rate. These results suggest that the endemic seagrass H. johnsonii could be negatively affected by hypo- or hypersalinity conditions, although salinity changes did not seem to alter the tolerance of this species to other environmental factors, such as temperature or pH.     

Phytoavailability and potential transfer of Pb from a salt-affected soil to Atriplex verucifera,Salicornia europaea and Chenopodium album

The phytoavailability and potential transfer of Pb to Atriplex verucifera, Salicornia europaea and Chenopodium album in two calcareous soils with different salinity/sodicity were compared. The soils were spiked with 0, 250, 500 and 1000 mg Pb kg^?1 soil. Plant shoots were harvested and analysed for total Pb after they had been grown in the contaminated soils. Visual MINTEQ 3.0 was used to calculate the speciation of soluble Pb in the experimental soils. Results showed that although the concentrations of 1 M NH₄NO₃-extractable Pb were relatively similar, speciation of Pb in the soils were not the same. Salicornia europea was found to be the most salinity/sodicity-tolerant plant. When the plants were grown in non-saline soil, the Pb tolerance of the three plants was as follows: A. verucifera > C. album >S. europea, whereas in saline (sodic) soil, Pb tolerance was in the order S. europea > C. album > A. verucifera. Lead phytotoxicity to A. verucifera and C. album was higher in the saline soil, whereas for S. europea, Pb toxicity was higher in the non-saline soil. It could be concluded that the phytoavailability of Pb and its interactions with plants are widely dependent on soil salinity level and type of plant.     

Interactions between temperature and salinity during brooding on subsequent zoeal development of the mud crab Rhithropanopeus harrisii

Female mud crabs, Rhithropanopeus harrisii, carrying newly extruded eggs, were collected from the Petaluma River (San Francisco Bay Estuarine System, California, USA) in summer 1985, and exposed to factorial combinations of temperature (20°, 25° or 30°C) and salinity (2, 5, 15, 25, or 32%.). Upon hatching, dry weights of 12 to 15 h-old zoeae were determined. Subgroups of the remaining zoeae were transferred from hatching salinities to the salinities listed above and raised until metamorphosis to megalopa. Low salinities reduced zoeal dry weights by as much as 25%. Temperature played a secondary role in reduction of hatching weight of zoeae. Survival of larvae through zoeal development was best when hatching and rearing salinities were the same; in this case, overall survival increased with temperature. Both duration of zoeal development and megalopal dry weights were strongly influenced by temperature and rearing salinity, with only a small contribution from hatching salinity. The influence of hatching salinity was most obvious at extremes of the range tested. These studies indicate that physical conditions during embryogenesis profoundly influence subsequent larval development. Interpretation of experimental approaches to study ecophysiological adaptations of larval stages should not neglect the role of physical conditions during embryogenesis.     

Phytoaccumulation of iron by callus tissue of Clerodendrum indicum (L)

Clerodendrum indicum (L.) is one of the important medicinal plants, originating in India. The plant is used as medicine for bronchitis, asthma and different immunological disease. Micro-propagation is a quick method, producing a huge number of plants. Apical leaf of Clerodendrum indicum (L.) was used as an explant for callogenesis. The combinations of different plant growth regulators (2,4-D, NAA, KN) in MS (Murashige and Skoog) medium produced two types of calli: one was friable and loose and the other was green, embryogenic and compact. Heavy metals cause pollution and health hazards. The plant absorbs heavy metals, which is very useful for controlling environmental pollution. Iron is a major nutrient for both plants and animals, but hyper accumulation of iron is injurious to health. Calli were used to study the optimum conditions of iron uptake in presence of different chemical environments. The different environments were created by using different chemical reagents such as (HCL, HNO₃, H₃PO₄ and KNO₃). Iron (III) was spiked with radioactive Fe-59 and dynamics of uptake was followed by measuring radioactivity by gamma-ray spectrometer. The best condition of iron uptake corresponded to 1 mol L^?1 KNO₃ after 4 hour of equilibration.     

Effects of abiotic factors on growth and chemical defenses in cultivated clones of <Emphasis Type="Italic">Laurencia dendroidea</Emphasis> J. Agardh (Ceramiales,Rhodophyta)

Laurencia dendroidea shows high inter- and intrapopulation variability in the amount of the sesquiterpene elatol, caused by genetic variation as well as environmental factors. To test the independent effect of physical and nutritional conditions, the growth and the levels of elatol in L. dendroidea clones were evaluated under different conditions of temperature, salinity, irradiance, and culture medium in the laboratory. Growth of L. dendroidea was clearly affected by all these factors, but elatol levels were influenced only by temperature and salinity. Better conditions for growth did not produce a similar effect on elatol production in L. dendroidea, contradicting the carbon/nutrient balance and growth/differentiation balance models. On the contrary, severe conditions of temperature and salinity promoted a decrease in elatol levels, as predicted by the environmental stress model. Our results using clones indicated that abiotic factors clearly take part in fostering chemical variations observed in natural populations, in addition to genetic factors, and can promote differential susceptibility of plant specimens to natural enemies.     

Kelp (<Emphasis Type="Italic">Laminaria digitata</Emphasis>) increases germination and affects rooting and plant vigour in crops and native plants from an arable grassland in the Outer Hebrides,Scotland

Kelp and other seaweeds are traditionally used in many parts of the world as a soil amendment on arable fields. Seaweeds contain biochemical compounds that can act as plant growth regulators in terrestrial plants. In a low-intensity arable grassland in northwest Scotland an organic fertilizer, kelp (Laminaria digitata) has been used for hundreds of years, due to its anticipated positive effect as a soil conditioner and provider of plant nutrients. In this study the effects of kelp on germination and rooting of crops and native plants from this area were investigated in soil-free media. Germination was studied by incubation in the presence of kelp solutions. Rooting of plant cuttings was assessed after a pulse treatment with kelp solutions, and indole-3 acetic acid (IAA) as a reference plant growth regulator. Germination percentage of Plantago lanceolata, Trifolium repens and Avena strigosa seeds increased significantly when incubated with 0.05% kelp solutions. Total root weight and the individual weight of roots produced in cuttings of Vigna radiata and P. lanceolata were significantly increased when exposed to a 0.5% solution of kelp. Plant vigour, assessed visually, decreased significantly for P. lanceolata exposed to kelp at concentrations of 0.5 and 5.0% indicating the presence of a threshold level for an inhibitory effect of kelp at these concentrations, which may be due to high salinity. The results confirmed the presence of plant growth regulators in kelp, and indicates that amendment with kelp may potentially affect plant community composition. The threshold levels where some plants responded negatively to kelp amendment were close to or lower than the theoretical concentrations of kelp in soil water at field conditions with the current doses used on the machair, indicating that care should be taken in either administering kelp at the appropriate dose or leaching out salt before application.     

Response of tomato (Lycopersicon esculentum Mill.) to salinity in the early growth stages for agricultural cultivation in saline environments

Salinity is a serious environmental problem. Growing of plants like tomato can be solution for coping with soil salinity. For this purpose, response of tomato to salinity has been tested in the early growth stages. Characteristics of germination (percentage and period; length and fresh-dry weight of radicle and hypcotyl) and seedling (length and fresh-dry weight of root, shoot and whole plant; leaf number and area based on Relative Growth Rate); Na+ and K+ content of leaf; K+/Na+ rate of leaf has been studied at the 0, 50, 100 and 150 mM NaCl levels. Thus, it determined that tomato can be indicator for agricultural cultivation at the salinity environments at the early growth stages.     

Water stress alters aphid-induced glucosinolate response in Brassica oleracea var. italica differently

Glucosinolates (GS) are the main secondary metabolites in brassicaceous plants that play an important role in plant defense and plant–insect communication. GS biosynthesis in plants and their accumulation may be influenced by biotic and abiotic stressors from the environment. In the present study, GS levels in broccoli plants, Brassica oleracea var. italica Plenck, grown under different water status conditions of soil—well-watered, drought and waterlogged—were determined after two aphid species, the specialist Brevicoryne brassicae (L.) and the generalist Myzus persicae (Sulzer), had fed on them for 7 days. High-performance liquid chromatography analysis revealed that GS levels were significantly induced after B. brassicae had fed on B. italica plants grown for 2 weeks under the various water status conditions. No significant differences were determined between GS induction in the three treatments. In contrast, the induction of GS after M. persicae had fed on the plants depended greatly on water stress levels. GS content in well-watered plants increased more significantly than in plants grown under drought conditions. Feeding by M. persicae did not increase GS levels when plants were grown under waterlogged conditions. The lowest plant growth were found in M. persicae-infested plants for all three water treatments, and measurements of GS showed that the induction of GS by M. persicae decreased in line with the reduction in infested plant growth. GS induction by B. brassicae did not alter remarkably following change in plant growth under water stress. Only one of the five glucosinolates detected, the aliphatic GS 4-methylsulfinylbutyl, remained unchanged after feeding of both, M. persicae and B. brassicae, on plants under water stress. Variation in GS levels was mainly observed for the induction of indolyl GS due to aphid herbivory, but changes in indol-3-ylmethyl GS were not always consistent with the induction of other indolyl GS.     

Controlling bacterial leaf blight of rice and enhancing the plant growth with endophytic and rhizobacterial Bacillus strains

This study was conducted to assess efficacy of biological control against bacterial leaf blight (BLB) of rice produced by Xanthomonas oryzae pv. oryzae. Five endophytic strains (A1, A2, A3, A13 and A15) and two rhizospherial Bacilli (D29 and H8) were tested for their antagonistic activities against BLB in vitro and in vivo. All seven strains showed high potential of antagonistic activity against X. oryzae pv. oryzae and three phytopathogenic fungi in vitro. Test of 16SrRNA gene sequence were assigned isolates A1, A3 and A13 as Bacillus amyloliquefaciens while isolates A2 and A15 as B. methylotrophicus and B. subtilis, respectively. In greenhouse, four strains of displayed 50.29%–57.86% inhibition rate against the pathogen and significantly increased plant fresh weight from 50.03% to 73.11% and dry weight from 64.11% to 86.65% in treated rice plants. In addition, these strains demonstrated strong capability to produce indole-3-acetic acid, siderophores, solubilizing phosphate and also colonize roots. Real-time quantitative polymerase chain reaction revealed that expression of defense-related genes including OsAOS2, OsJMT1, OsNPR1 and OsPR1b were significantly up-regulated in leaves of D29-exposed rice plants, suggesting that treatment of rice with D29 suppressed BLB through systemic activation of the plant defense system. Therefore, data suggest that Bacillus isolates A13, A15, D29 and H8 support effective antagonistic activity against BLB under greenhouse conditions in addition to their potential to promote growth of rice plants.     

o-Coumaric acid from invasive Eupatorium adenophorum is a potent phytotoxin

A phytochemical study of the invasive Eupatorium adenophorum indicated that the plant was rich in a phenolic compound o-coumaric acid (or 2-hydroxycoumaric acid). Biological investigations with the model plant Arabidopsis thaliana and crop plants showed that o-coumaric acid strongly inhibited seed germination, plant growth and root elongation, reduced the photosynthesis in old leaves, and induced the root cell death and the expression of genes related to senescence, oxidative stress, and systemic acquired resistance. The phytotoxic effects of o-coumaric acid exhibit selectivity between under- and above-ground parts of test plants and between E. adenophorum and other plants. These results indicate that o-coumaric acid is a potent toxin that might play an important role in the competition of E. adenophorum with its neighboring plants during its invasion and establishment.     

Effect of Water Variables On Lead Tolerance in Postlarvae of Penaeus Indicus (H. Milne Edwards)

Lead tolerance in Penaeus indicus post-larvae (PL) was studied in relation to the water variables: salinity, temperature and pH. the LC₅₀ for 96 hrs was 7.22 ppm at ambient conditions of salinity (20%_o), temperature (29°C) and pH (7.2). the post-larvae were found to be sensitive to salinity variations with a significant (P < 0.05) low LC₅₀ values at lower (2%_o) and higher (29%_o) ranges. Though a decrease in LC₅₀ value was observed both at higher (45°C) and lower (10°C) temperatures, it was significantly (P < 0.05) low only at higher temperature indicating more toxicity. the LC₅₀ values also showed a significant (P < 0.05) decrease in acidic (pH 2.8) and alkaline (pH 11.0) conditions. the data indicate that lead toxicity increases in the PL of P. indicus with variations in the water variables.     

Effects of environmental parameters on the oxygen consumption of four marine invertebrates: a comparative factorial study

The oxygen consumption curves of two decapod crustaceans (Palaemon serratus, Penaeus monodon) and two prosobranch molluscs (Trunculariopsis trunculus, Nassarius mutabilis) have been detected in the entire pO₂ interval from 0 to 160 mmHg, under different conditions of temperature and salinity. From the experimental curves, physiological parameters such as the initial oxygen consumption velocity, the Q ₁₀ values and the oxygen independence indices have been measured. The latter parameters have been obtained using normalised plots which allow their better evaluation. The effects of temperature, salinity and oxygen partial pressure on the oxygen-consumption features have been studied using a factorial experimental plan which allows measurement of the effects of each experimental variable as well as the effects of synergistic interactions between different variables. Received: 27 March 2000 / Accepted: 13 November 2000     

Mechanisms mediating plant distributions across estuarine landscapes in a low-latitude tidal estuary

Understanding of how plant communities are organized and will respond to global changes requires an understanding of how plant species respond to multiple environmental gradients. We examined the mechanisms mediating the distribution patterns of tidal marsh plants along an estuarine gradient in Georgia (USA) using a combination of field transplant experiments and monitoring. Our results could not be fully explained by the "competition-to-stress hypothesis" (the current paradigm explaining plant distributions across estuarine landscapes). This hypothesis states that the upstream limits of plant distributions are determined by competition, and the downstream limits by abiotic stress. We found that competition was generally strong in freshwater and brackish marshes, and that conditions in brackish and salt marshes were stressful to freshwater marsh plants, results consistent with the competition-to-stress hypothesis. Four other aspects of our results, however, were not explained by the competition-to-stress hypothesis. First, several halophytes found the freshwater habitat stressful and performed best (in the absence of competition) in brackish or salt marshes. Second, the upstream distribution of one species was determined by the combination of both abiotic and biotic (competition) factors. Third, marsh productivity (estimated by standing biomass) was a better predictor of relative biotic interaction intensity (RII) than was salinity or flooding, suggesting that productivity is a better indicator of plant stress than salinity or flooding gradients. Fourth, facilitation played a role in mediating the distribution patterns of some plants. Our results illustrate that even apparently simple abiotic gradients can encompass surprisingly complex processes mediating plant distributions.     

Genetic experssion of temperature tolerance in the copepod Eurytemora affinis in different salinity and temperature environments

The genetic expression of temperature tolerance in Eurytemora affinis Poppe in different environments was investigated by testing temperature tolerances of broods in pairs of salinity and temperature environments. Three methods were used to identify interaction between genotype and environment: (1) the correlation between mean tolerances of halves of broods grown in the two environments, (2) brood by environment interaction and (3) heritabilities in the two environments. All correlations between means of half broods were positive, only one of six brood by environment interactions was significant and the heritability estimates were not markedly different. Thus, the variability in temperature tolerance in different salinities and in different temperatures seems to be due to the same genes; and selection pressure on temperature tolerance is in the same direction with seasonal changes in temperature and salinity.