Mean Emergence Time Research Articles

Effect of add-on Gabapentin premedication on hemodynamic response to skull pin insertion.

Background and Aims:Effectiveness of oral gabapentin premedication in suppressing response to laryngoscopy and tracheal intubation suggests its potential for attenuating skull pin insertion response. The present study was therefore planned to evaluate the effect of add-on oral gabapentin premedication to local anesthetic injection at pin insertion site in obtunding hemodynamic response.Material and Methods:Sixty adult patients posted for elective craniotomy were enrolled for a prospective, randomized and double-blinded study. Group I patients received gabapentin 900 mg orally as premedication whereas Group II patients received oral placebo. Both groups were administered subcutaneous (s.c.) injection (Inj) 2% lignocaine 2 mL at all four pin insertion sites. Mean arterial pressure (MAP) and heart rate (HR) were measured every 30 s for the initial 10 min. Increases in HR beyond 20% and MAP 30% above baseline were treated with bolus intravenous (IV) Inj propofol 30 mg. Quantitative data was compared using Student’s t-test and Mann Whitney U test, while categorical data was compared using Chi-square (χ2) test.Results:The increase in HR and MAP from baseline was significantly greater and it remained above baseline levels longer in Group II as compared to Group I. Twenty-one patients (70%) received rescue boluses of propofol with a mean dose of 45.00 ± 39.98 mg in Group II as compared to nine (30%) patients receiving mean of 18.20 ± 29.04 mg in Group I. (P = 0.015). The mean emergence time and sedation scores in both the groups were statistically similar (P = 0.060).The incidence of adverse effects like hypotension, bradycardia, nausea/vomiting, sedation or dry mouth were similar in both the groups.Conclusion:Add-on oral gabapentin premedication potentiates the effect of s.c. lignocaine Inj for suppression of skull pin insertion response.

A Moderate Mitigation Can Significantly Delay the Emergence of Compound Hot Extremes

AbstractCompound hot extremes (ChotEs) that refer to continuous heats throughout days and nights are projected to increase, causing more serious impacts on human health than daytime or nighttime heats alone. Previous studies have focused on daytime heats, but the timing of substantial increase in ChotEs relative to natural variability, which is defined as the time of emergence (ToE) for ChotEs, remains unknown. Here we examine ToE for duration of summertime ChotEs from coupled model intercomparison project phase 6 climate model projections under two shared socioeconomic pathway scenarios (i.e., SSP245 and SSP585). We further quantify the cumulative fraction of areal and population exposed to the emergence at global and continental scales. We find that, without implementation of climate mitigation policies (i.e., SSP585), global mean ToE is around 2062 (with 16%–84% uncertainty range of 2048–2072). On the basis of the ToE for each grid cell, 80.7% (with uncertainty range of 64.2%–96.7%) of global lands will expose to the emergence by 2080. Such substantial increases in ChotEs will lead to 75.2% (66.8%–93%) of global population exposed to the emergence by the end of 21st century. A moderate mitigation (i.e., SSP245) can delay the ToE by over 14 years and, more importantly, reduce the global land areal and population exposures by 50.3% and 39.7% respectively. Regionally, northern Europe, central America and western North America benefit the most. Therefore, early action towards moderate development socioeconomic pathways can remarkably cut back the possibility of large population exposure to ChotEs and relevant impacts.

Application of Moringa Leaf Extract as a Seed Priming Agent Enhances Growth and Physiological Attributes of Rice Seedlings Cultivated under Water Deficit Regime.

Population growth, food shortages, climate change and water scarcity are some of the frightening challenges being confronted in today’s world. Water deficit or drought stress has been considered a severe limitation for the productivity of rice, a widely popular nutritive cereal crop and the staple food of a large portion of the population. A key stage in crop growth is seed emergence, which is mostly constrained by abiotic elements such as high temperatures, soil crusting and low water potential, which are responsible for poor stand establishment. Seed priming is a pre-sowing treatment of seeds that primes them to a physiological state that allows them to emerge more proficiently. The purpose of this study was to investigate the potential of leaf extracts from local and exotic moringa landraces as seed priming agents in rice cultivated under water deficit (75% field capacity) and control conditions (100% field capacity). Rice seeds were placed in an aerated solution of moringa leaf extract (MLE) at 3% from three obtained landraces (Faisalabad, Multan and an exotic landrace of India). The results obtained from the experimentation show that the water deficit regime adversely affected the studied indicators including emergence and growth attributes as well as physiological parameters. Among the priming agents, MLE from the Faisalabad landrace significantly improved the speed and spread of emergence of rice seedlings (time to start emergence at 23%, emergence index at 75%, mean emergence time at 3.58% and final emergence percentage at 46%). All the priming agents enhanced the growth, photosynthetic pigments, gas exchange parameters and antioxidant activities, particularly under the water deficit regime, but the maximum improvement was recorded by the MLE from the Faisalabad landrace. Therefore, the MLE of the Faisalabad landrace can be productively used to boost the seedling establishment and growth of rice grown under normal and water deficit conditions.

The effects of different seed priming agents on improving emergence, growth, yield and essential oil percentage of purple coneflower (Echinacea angustifolia DC.) under field condition

Purple coneflower (Echinacea angustifolia DC. var. angustifolia) is an important medicinal plant in pharmacological industry. This plant is produced in commercial scale but their seeds exhibit low germination percentages under field conditions. Enhancing seed germination is thus crucial for improving the production of E. angustifolia. The influence of Ethephon, Gibberellic acid (GA3) and moringa leaf extract on emergence, growth attributes, yield attributing characteristics and essential oil percentage of purple coneflower (E. angustifolia) were investigated. Freshly harvested seeds of E. angustifolia were treated with 0.5, 1 and 2mM of ethephon, 2000 2500 and 3000mg/l of gibberellic acid (GA3) and 5, 10 and 15% of moringa leaf extract (MLE). Then, seeds were stratified at 4oC for 4 weeks in light. All the priming treatments were evaluated for the emergence, growth attributes, yield attributing characteristics and essential oil percentage. Among different treatments MLE-priming at 10% could be recommended, as it was the best in terms of final emergence percentage (96%), mean emergence time (4.78 days), α-amylase activity (52.15 IU/mg), total soluble sugars (61.41 mg/g), reducing sugars (54.19 mg/g), plant height (98.82 cm), number of branches (28.36), biological yield (14.08 ton/h) and root yield dry (8.88 ton/h) and essential oil percentage (0.62 %). Moringa leaf extract (10%) is recommended as a priming agent to overcome seed dormancy and improve the emergence, growth, yield and essential oil percentage of E. angustifolia.

Do native plant species functionally similar to invasive species suffer more impacts from the invasion in seasonally dry tropical forests?

Abstract We tested the hypothesis that of the species studied in the Brazilian Semiarid, the ones most functionally similar to tree Azadirachta indicawould be more affected by this exotic species during germination and early development. At first, we produced a crude extract of A. indica fresh leaves in six different dilutions. We placed 25 seeds of four native species ( Cenostigma pyramidale, Libidibia ferrea, Mimosa caesalpiniifolia, and Amburana cearensis) to germinate in Petri dishes for each dilution, with four replicates for each species. We assessed: radicle length, emergence percentage, emergence speed index, and mean emergence time. We conducted an experiment in a greenhouse to assess how the exotic plant affected the development of individual plants of the studied species. We planted five seeds of each native species alone and five in interaction with the exotic species using ten 20-l buckets. The experiment lasted four months, and the functional attributes of the individuals were collected. Among the native species analyzed, according to the cluster analysis using the functional attributes of the species planted alone, M. caesalpiniifolia, C. pyramidaleand L. ferreawere functionally more similar to the exotic species. In the germination experiment, the extract affected only root length, regardless of the functional similarity. We noticed that only M. caesalpiniifoliahad its early development strongly inhibited when planted in interaction with the exotic species. Although the functional similarity between the exotic and the native species did not influence germination, it negatively affected the development.

Effect of ultrasonic treatment on seed germination and seedling emergence in seven vegetable species

This study was performed to determine the effect of ultrasound treatment on seed germination, seedling emergence and mean germination and emergence times in seeds of watermelon, melon, leek, pepper, carrot, tomato and aubergine. Seeds treated with 40 kHz ultrasound over 30 minutes (US), hydroprimed seeds (HP) and dry controls (C) were tested. US-treated seeds had 85% mean germination percentages compared to 82 and 78% for HP and C seeds, respectively. Corresponding values for seedling emergence were 83, 75 and 72%. US treatment reduced mean germination and emergence times. The maximum advantages obtained from US in germination were observed in watermelon (13%), carrot (11%), pepper (13%), leek (10%), and pepper (7%) compared to C and HP seeds, respectively. Advantages in seedling emergence obtained by US were greatest in watermelon (20%), leek (22%) and tomato (13%) compared to C and for pepper (14%), tomato (12%), melon (11%), watermelon (10%) and leek (10%) compared to HP. US treatment reduced both germination and emergence times. Results showed that US treatment was more effective on seedling emergence than germination. US treatments have the potential to increase germination and seedling emergence in vegetable seeds.

Allelopathic activity of Piptadenia moniliformis Benth. on the physiological potential of seeds of Amburana cearensis Allem.

The adoption of agroforestry systems or reforestation programs contributes to the economy of a region in a sustainable way, since the adopted species can be exploited by the cosmeceutical and pharmaceutical industries. For the establishment of plant species in a given area, studies are needed on the interaction that can develop between them, with emphasis on research on allelopathy. Given the above, the aim of this study was to evaluate the allelopathic effect of the aqueous extract of leaves of the native species Piptadenia moniliformis on the initial development of the forest species Amburana cearensis. The aqueous extract was used at different concentrations. (0 - water, 25, 50, 75 and 100%), adopting a completely randomized design. The following characteristics were evaluated: emergence percentage, emergence speed index, mean emergence time, shoot and root length and total shoot, root and total dry part of normal seedlings. The 100% concentration of the aqueous extract of P. moniliformis leaves reduced the emergence percentage of A. cearensis seedlings. A smaller number of normal seedlings was observed at concentrations of 75 and 100%. The initial development of seedlings was hampered by the increase in extract concentrations. The aqueous extract of fresh leaves of P. moniliformis provides a negative allelopathic effect for both emergence and early development of A. cearensis seedlings, therefore intercropped cultivation among the forest species is not recommended.

Impact of Biochar Application on Germination Behavior and Early Growth of Maize Seedlings: Insights from a Growth Room Experiment

Reduced germination and early crop maturity due to soil compaction, nutrients stress, and low moisture are major constraints to achieve optimum crop yield, ultimately resulting in significant economic damages and food shortages. Biochar, having the potential to improve physical and chemical properties of soil, can also improve nutrients and moisture access to plants. In the present study, a growth room experiment was conducted to assess biochar influence on maize seed germination, early growth of seedlings, and its physiological attributes. Corn cob biochar (CCB) was mixed with soil at different rates (0.5%, 1%, 1.5%, 2%, 2.5%, and 3% w/w) before seed sowing. Results obtained showed that increasing CCB application rate have neutral to positive effects on seed germination and seedling growth of maize. Biochar addition at the rate of 1.5% (w/w) significantly increased shoot dry biomass (40%), root dry biomass (32%), total chlorophyll content (a and b) (55%), germination percentage (13%), seedling vigor (85%), and relative water content (RWC) (68%), in comparison to un-amended control treatment. In addition to this, it also improved germination rate (GR) by 3% as compared to control treatment, while causing a reduction in mean emergence time (MET). Moreover, application of biochar (3%) also resulted in enhancement of antioxidant enzyme activity, particularly superoxide dismutase (SOD) and catalase (CAT) by 13% and 17%, respectively. Conclusively, biochar application is an attractive approach to improve the initial phase of plant growth and provide better crop stand and essential sustainable high yields.

Photoperiod is an important seasonal selection factor in Chironomus riparius (Diptera: Chironomidae)

Abstract Most organisms respond and can adapt to photoperiodic changes. This affects measurable end points like developmental time, survival and fertility. For ectotherms like Chironomus riparius, temperature is the most studied environmental cue regulating their life cycle, whereas photoperiodic influence is neglected. However, the developmental speed between summer and winter seasons of a field population could not be explained solely by temperature variations. Therefore, to have a comprehensive view on how photoperiods influence chironomid’s life cycle, we investigated if it plays a role in their development and if it acts as an important selective pressure on developmental time speed. To this end, first emerged C. riparius were artificially selected for seven generations. Pre-selected and unselected organisms could develop and breed independently under three light regimes: constant light (24:0 L:D), long days (16:8 L:D) and short days (8:16 L:D). Adult emergence, mean and median emergence time and fertility were integrated into the population growth rate to compare fitness. Our findings show that although developmental time is extended under short days, this same condition may exert a selective pressure towards a shorter development. Moreover, by also using photoperiodic clues to anticipate environmental changes, chironomids can potentially adapt to alterations in climate.

Optimization of Operational Parameters of a Vacuum Single-Seed Planter for Sowing of Maize

The objective of the study was to evaluate the performance of a vacuum single-seed planter in field conditions to optimize some operating parameters in maize production. Three forward speed of the tractor (4.0, 5.4 and 7.9 km h-1) and five target seed spacing (102, 147, 195, 247 and 309 mm) were evaluated by examining the mean seed spacing, coefficient of precision in spacing, miss index, multiple index, quality of feed index, sowing depth, deviation from the row (inter-row spacing), mean emergence time, emergence rate index and percentage emergence. The point dropped in a furrow of seed, depth of seed placement, emergence rate and three indices of uniformity in seed spacing and precision coefficients of sowing quality were determined. The planter performed the best performance at the lowest forward speed and the highest target seed spacing. However, the deviation of seeds from the intended point in intra-row spacing was significantly affected only by the forward speed (P<0.001). Improvement in the larger seed spacing was due to the lower variation. Increasing the forward speed resulted in a shallower sowing depth. The desired planting depth was also obtained at 4.0 km h-1 in all plots. Increasing target seed spacing increased the emergence percent by about 35% while increasing forward speed decreased the emergence percent by 10%. Sowing at 4.0 km h-1 resulted in the lowest miss, multiple and precision indices (5.1% 2.9%, and 15.3%, respectively), and a quality of feed index as high as 92% was obtained in similar conditions. The results indicated that, with single-seed planters, success may be achieved in a conventional tillage maize production system at a target seed spacing of more than 102 mm and tractor forward speeds of less than 7.9 km h-1, and thus satisfying farmers who carry out maize sowing by conventional tillage.

SEEDLING EMERGENCE STABILITY OF BAMBARA GROUNDNUT [VIGNASUBTERRANEA L. (VERDC.)] UNDER SAVANNA AND HUMID RAIN FOREST AREAS CONDITIONS DURING TWO CROPPING SEASONS IN COTEDIVOIRE

The yield of Bambara groundnut [Vignasubterranea L. (Verdc.)] is extremely low and unpredictable. Erratic yields have been attributed, at least in part, to variable or poor field establishment due to seedling emergence. The aim of this study wasto evaluate under field conditions, the effects of genotype and environment on seedling emergence in Bambara groundnut. Field experiment was conducted with 15 landraces in Northern and Southern regions of Cote dIvoire. A randomized complete block design with five replications was used in each environment. Estimated variables included number of day for emergence (DFE), mean emergence time (MET), emergence index (EI), time to 50% emergence (T50) and seedling emergence percentage (EP). Analysis of variance revealed significant (P &lt; 0.05) differences between genotypes, locations and the interaction genotype x location for all traits studied. Location x year x genotype interactions were only significant for DFE, EI and EP.The highest DFE and T50 and MET were observed with the genotype Ci7. The least DFE, MET and T50 were obtained with genotypes Ci1, Ci2, Ci10, Ci11, Ci12, Ci13 and Ci22. Highest seedling emergence percentage was recorded with genotype Ci15 (93.29%) in Korhogo and Ci4 in Korhogo (90.85%) and Abidjan (89.59 %). Lowest EP was observed with the genotype Ci3 (42.33%).Correlations indicated that genotype with higher emergence percentage, emerged faster (low DFE, MET, T50) and exhibited higher emergence index (EI). AMMI analysis showed that Ci1, Ci4, Ci7, Ci11, Ci14 and Ci15 were the ideal genotypes because they expressed high and stable EP.

Field Emergence Affected by Zea Mays L. Cultivars and Seed Soaking in Acids of Ascorbic, Citric and Humic

A field experiment was carried out during the spring season 2019 and 2020 to obtain a fast, uniform, and high field emergence ratio of maize seeds under a wide range of environmental conditions. Randomize complete block design in the split-plot arrangement was used with three replications. The first factor in the main plots was cultivars (5018, Baghdad3 and Sumer). The second factor in the sub-plots was seeds soaking with ascorbic and citric acids (100 mg L−1) each and humic (1 ml L−1) in addition to control treatment (seeds soaking with distilled water only). Results showed the superiority of soaking with humic acid significantly, as means of characteristics of field emergence in both seasons, respectively, were as follows: Last day of field emergence (12.4 and 12.6 days), time spread of field emergence (4.4 and 4.6 days), emergence at first and final counts (62.4 and 34.4 %) and (95.8 and 88.0 %), daily emergence rate (8.0 and 7.3 % day−1), mean field emergence time (8.7 and 9.3 days), emergence index rate (11.1 and 9.7 % day−1), velocity coefficient of field emergence (11.4 and 10.8) and emergence index (407.6 and 333.3). Cultivars didn’t differentiate among themselves, with the effect of seeds soaking in most traits. It can be concluded that seeds soaking with humic acid improved characteristics of emergence and seedlings, so it can be recommended to soaking maize seeds with humic acid at the concentration (1 ml L−1) when planting them in the spring season.

EVALUATION OF GERMINATION, EMERGENCE AND PHYSIOLOGICAL PROPERTIES OF SUGAR BEET CULTIVARS UNDER SALINITY

This study aimed to determine a useful selection criterion for salt tolerance during the early development stage of sugar beet. Four sugar beet cultivars (Orthega, Valentina, FD Shoot, and Mohican) were exposed to NaCl stresses (Control, 5, 10, and 15 dS m-1), and morphological and physiological characteristics were investigated. Germination percentage, mean germination time (MGT), seedling length, and seedling fresh weight (SFW) in germination test; emergence percentage, mean emergence time (MET), root length, shoot length, plant fresh weight, relative chlorophyll content (Chl), relative water content (RWC) and electrolyte leakage of the plants grown in pod experiment were measured. The results showed that the maximum germination at control was recorded in FD Shoot, but it gave the lowest germination at 15 dS m-1. In the pod experiment, the highest emergence rate was detected in Orthega and Mohican at all levels of NaCl. Increased salinity delayed MET and led to reduction in shoot length, root length, and RWC of sugar beet cultivars. Relative Chl content and electrolyte leakage enhanced from 32.7 SPAD and 21.6% in control to 38.5 SPAD and 35.6% in 10 dS m-1, respectively. In general, there were significant differences among sugar beet cultivars, and they could keep the salinity up to 5 dS m-1 in terms of the investigated traits. It was concluded that relative Chl content and electrolyte leakage should be used a promising clue for selection of tolerant or sensitive sugar beet cultivars for salinity.

Priming with Humic Acid to Reverse Ageing Damage in Soybean [Glycine max (L.) Merrill.] Seeds

Soybean seed vigour declines with increase in storage duration, due to ageing, which can be alleviated through seed priming. The objective of this study was to investigate the effects of Humic acid (HA) priming on germination, vigour and seedling performance under laboratory and greenhouse conditions with two soil moisture level [50% and 80% field capacity (FC)]. Seeds stored for 12 months having 60% germination were primed either with 0.2 g/L HA solution or distilled water (hydro-primed) at 25 °C for 1, 3, 5 and 7 h. Non-primed dry seeds were used as control, giving nine treatment combinations. Various germination traits [mean germination time (MGT), final germination percentage (FG%), germination rate index (GRI), seedling emergence percentage (SEP)], mean emergence time (MET), seedling quality traits [seedling vigor index (SVI), shoot length, root length, root volume], antioxidant enzyme activities [catalase (CAT), peroxidase (POD)], lipid peroxidation [malondialdehyde (MDA)] and electrical conductivity (EC) were determined. A germination test in the laboratory was conducted as single factor (nine priming treatments), while the greenhouse experiment was conducted as two factors [2 soil moisture level (50 and 80% FC) and 9 priming treatments]. The results indicated that seeds primed with HA for 5 h was able to reinstate the CAT activities (25%), POD activities (50%) and reduced EC (51%) and MDA content (40%) compared with non-primed seeds, reduced the MET (from 4.3 to 3.5 days), increased FG% (from 62 to 71%), GRI (15.6–21.1) and SEP (from 35 to 54%) and (from 60 to 72%) at 50% FC level and 80% FC level, respectively. A strong negative correlation (r = −0.80 **) was found between MDA content and GRI, while CAT and POD activities had positive correlation with GRI r= 0.67 ** and r = 0.56 **, respectively. Thus, priming with 0.2 g/L HA for 5 h improved the vigour of minimally deteriorated soybean seeds resulting in increased emergence with more uniform field establishment.

Effects of different salt sources and salinity levels on emergence and seedling growth of faba bean genotypes

Suitability of poor quality water for irrigation depends on salinity level and solute concentration in the water and selected crop. Salt stress is a major potential constraint for faba bean. The present study aimed to investigate the effects of different Cl- and SO4-containing salt sources in irrigation water with different salinity levels on emergence, early seedling growth and photosynthetic capacity of six faba bean genotypes. The negative effect order of salinity level was high (3 dS/m) > medium (2 dS/m) > low (1 dS/m) > control (0.05 dS/m) for all investigated parameters except dry root weight. The negative effects of Cl-containing salt sources were higher than that of SO4-containing salt sources. The worst and the best performing genotypes were determined as III-28 and III-29 on emergence percentage at 10th DAS, I-29 and III-1 on mean emergence time, III-22 and III-1 on shoot height, III-1 and I-29 on fresh biomass weight, III-22 and III-28 on fresh shoot weight, III-29 and I-29 on fresh root weight, respectively. This study showed that faba bean genotypes have different behaviors in terms of response to the increasing salinity levels artificially makeup by using different salt sources indicating that salt response of faba bean is genotype-specific.

Emergence, photosynthesis, and seedling growth of bean genotypes, as affected by salt sources and salinity levels

ABSTRACT The type and amount of salt present in water determine the suitability of water for irrigation. The aim of this study was to determine the effects of different salt sources (SS) and different salinity levels (SLs) in irrigation water on photosynthetic capacity, emergence and seedling growth parameters of eight bean (Phaseolus vulgaris L.) genotypes (G). The experiment was designed as a three-factorial split–split plot under a rain-out shelter. The G × SS × SL interaction for all investigated parameters was statistically significant. In general, GV-51, VN-50 and ML-34 genotypes were not adversely affected by increasing SL with respect to CaCl2, MgCl2 and CaSO4 salts. However, compared to the control, VN-8 and TR-64995 genotypes showed the lowest percent emergence from 2 and 3 dS m−1 with all salt sources, except VN-8 with CaSO4 salt. None of the genotypes showed significant differences for mean emergence time with increasing SL of CaSO4 salt. The highest shoot length was obtained for Helda genotype under control SL. Considering all genotypes, the values ranged from 0.533 to 0.740 for Fv/Fm ratio, 3.36 to 3.38 g for biomass weight, 1.82 to 4.75 g for shoot weight, and 1.42 to 4.50 g for root weight. Genotypic differences existed for salinity tolerance for emergence and early seedling growth, and the effects of salinity depended not only on the amount of salt but also on the kind of salt present in the irrigation water.

Exogenous Antioxidants Enhance Seedling Growth and Yield of Artificially Aged Cabbage and Lettuce Seeds

Aged seeds exhibit compromised vigour in terms of germination, seedling emergence and growth, but this can to some extent be alleviated by invigoration treatments before sowing. This study aimed to investigate ageing rates and patterns in cabbage (Brassica oleraceae) and lettuce (Lactuca sativa) seeds and whether the beneficial effects of invigorating aged seeds with exogenous antioxidants translate to enhanced seedling performance. Seeds were artificially aged to 25% viability before soaking in 0.4 mM glycerol, 0.6 mM GSH and 0.2 mM trolox for cabbage, and 0.6 mM glycerol, GSH and trolox for lettuce; deionised water served as a control. After 14 days of sowing, seedling emergence percentage, mean emergence time, mean daily emergence, and time taken to 25% emergence were computed. Seedling vigour index, root and shoot dry weight, root:shoot ratio, leaf area, leaf area ratio, and leaf chlorophyll content were assessed 6 weeks after sowing. Furthermore, the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), and chlorophyll fluorescence were measured 6 weeks after sowing. Notably, ageing resulted in the loss of seed vigour and viability at higher rates in lettuce than cabbage. Seed pretreatment with glycerol promoted seedling growth in both species and shoot dry weight in lettuce, while glycerol and GSH enhanced Pn, Gs and E in lettuce. Trolox also enhanced Pn and E in lettuce. The beneficial effects of the antioxidant treatments are thought to be associated with the protection of photosystems from oxidative stress and/or stimulation of enzymes involved in photosynthesis, possibly through an enhanced antioxidant defence system during the early development stages when seedlings are particularly vulnerable to stress.

Emergence and development of Dianthus chinensis and Limonium sinuatum seedlings on commercial substrate

Limonium sinuatum and Dianthus chinensis are plant species of great importance in Brazilian floriculture, being propagated by seed, therefore, the characteristics of the substrates used are respectable in seedlings emergence and development process. Thus, the objective of this research was to evaluate the influence of two commercial substrates on emergence and development of Limonium sinuatum and Dianthus chinensis seedlings. The experiment was conducted in a greenhouse (Pad &amp; Fan type) at São Paulo State University. The treatments were: T1 – Basaplant® and T2 – Tropstrato®, for both species, whose seeds were germinated in expanded polystyrene trays of 128 cells, being eight replicates, containing 8 seeds/replicate. The evaluated traits were: percentage of emergence, emergence speed index, mean emergence time, shoot height, root length and seedlings fresh and dry mass. The substrate characteristics evaluated were: pH, electrical conductivity, macroporosity, microporosity, total porosity, density and water retention capacity. The experimental design was completely randomized, and data were submitted to analysis of variance to Tukey test at 5% to compare the means. The emergence of Limonium sinuatum and Dianthus chinensis were impaired, possibly due to low electrical conductivity provided by substrates. However, Basaplant® substrate favoured the development of evaluated species in relation to aerial part length, root length and total fresh and dry mass, which is recommended for using as substrate for both species.

Artificial light reduces foraging opportunities in wild least horseshoe bats

Artificial light at night has been proposed as a global threat to biodiversity. Insectivorous bats are strictly nocturnal animals that are vulnerable to disruption from artificial light. Given that many light-sensitive bats tend to avoid night light during roost departure, it is often assumed that nighttime light pollution reduces their foraging opportunities, albeit empirical evidence in support of this hypothesis remains elusive. Here, we used least horseshoe bats, Rhinolophus pusillus, to assess whether white artificial light is detrimental for the opportunities of foraging. We manipulated the levels of ambient illumination and perceived predation risk inside the bat roost. We monitored bats' emergence activity using high-speed video and audio recording systems. DNA-based faecal dietary analysis and insect survey were applied to determine activity time of prey in foraging areas. Following experimentally manipulation of white light-emitting diode (LED) lighting 0–15 min after sunset, bat pass, flight duration, and echolocation pulse emission decreased. The mean emergence time of bats flying out was delayed by 14 min under lit treatment compared with the dark control. Only 10% of bats left for foraging during 40 min of light exposure. Aversive effects of LED light on bat emergence were robust regardless of the presence of a potential predator. Insect prey reached a peak of abundance between 30 and 60 min after sunset. These results demonstrate that white artificial light hinders evening emergence behavior in least horseshoe bats, leading to a mismatch between foraging onset and peak food availability. Our findings highlight that light pollution overrides foraging onset, suggesting the importance of improving artificial lighting scheme near the roosts of light-sensitive bats.

A, The Evaluating Allelopathic potential of aqueous extracts of Sow thistle (Sonchus oleraceus L.) on emergence and seedling growth of Red rice (Oryza punctata)

ABSTRACT Chemical weed control method caused environmental hazards and residual effects in crops and soil. Alternate approach to control weeds is getting attentions in sustainable production system. Use of aqueous extracts of weed is getting scientific attention as eco-friendly alternative to chemical herbicides especially under scenario of fast increasing herbicide resistance in weeds. To investigate the herbicidal potential of aqueous extract of winter weed of Sonchus oleraceus L. (Sow thistle) on summer weed Oryza punctate L. (red rice) seed emergence and initial seedling growth, a study was planned. In this study, seeds of O. punctate were incubated in seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different parts i.e. leaves, stem, flower of S. oleraceus. All the tested concentrations of various plant parts of S. oleraceus significantly inhibited the mean emergence time, emergence index, emergence percentage (%), time taken to 50% emergence as well as growth of O. punctata weed. However, maximum mean emergence time (5.26 days), minimum germination index (1.69), germination percentage (40%), root length (2.04 cm), shoot length (5.71 cm), fresh weight (59 g), dry weight (4.06 g) was noted at 8% concentration with fruit aqueous extract of S. oleraceus. Seed of O. punctata take maximum time to complete 50% emergence (3.33 days) under control where we applied distilled water. Results suggested fruit extract of S. oleraceus at 8% concentration can be used potential bio-herbicide for the control of O. punctate. Key words: Chemical, eco-friendly, herbicidal potential, fruit extract