Diurnal and Seasonal Variations of Particulate Matter Concentrations in the Urban Forests of Saetgang Ecological Park in Seoul, Korea

Urban forests provide various ecosystem services. Although the function of reducing particulate matter (PM) in the city is known, research into the reduction of PM according to the type and structure of various forests is still needed. It is essential to study the characteristics of PM concentration in urban riparian forests, which are frequently used for outdoor walks in the COVID-19 era. In this study, the diurnal and seasonal changes in PM10 and PM2.5 concentrations were analyzed in urban forests with different structures in the riparian forests located in central Seoul. The PM concentration was found to be high regardless of the time of the day in forests with a developed canopy layer. Similar results were found before and after leaf emergence compared with the seasonal PM concentration. The results of this study highlight the need for planned and periodic management of the canopy layer and underground vegetation to prevent the PM trapping effect to ensure the safe use of riparian forests in cities.

Impact of Trichoderma asperellum on Chilling and Drought Stress in Tomato (Solanum lycopersicum)

The acceleration of climate change is necessitating the adoption of shifts in farming practices and technology to ensure the sustainability of agricultural production and food security. Because abiotic stresses such as drought and chilling represent major constraints on agricultural productivity worldwide, in this study, the mitigation of such stresses by the fungus Trichoderma asperellum HK703 was evaluated. The fungus was grown on whole grain oats, kaolin and vermiculite for 5 days and then the formulation was mixed with the potting soil to colonize the roots of the plants. The effect of the bioinoculant on tomato under drought or chilling was analyzed in tomato (Solanum lycopersicum) plants. Leaf, stem and root succulence, electrolyte leakage, the relative growth rate of plant height, stem thickness and leaf area, as well new leaf emergence and chlorophyll content were determined. The results showed that drought or chilling increased electrolyte leakage and reduced plant growth and development traits and chlorophyll (a,b) content. However, inoculation with T. asperellum eliminated or reduced most of the negative impacts of drought compared to the non-stressed plants, with the exception of chlorophyll b content. Furthermore, inoculation with T. asperellum improved some of the evaluated features in chilling stressed plants but had no effect on plant height or chlorophyll (a,b) content. The results of this study indicate that T. asperellum was more effective in alleviating drought than chilling stress in tomato plants.

PHENOLOGY, REPRODUCTIVE BIOLOGY AND SPATIAL DISTRIBUTION OF Chresta scapigera (LESS.) Gardner (ASTERACEAE)

Chrestas capigera (Less.) Gardner is an important medicinal herb which, however, has been poorly studied for its biology and ecology. This study aimed to investigate its phenology, floral biology, reproductive biology (self-pollination tests), spatial distribution and correlations between phenophases and climatic data in two sites (Cerrado stricto sensu and Campo rupestre) in southern Minas Gerais, Brazil. From August of 2012 to August of 2013, we monitored phenophase occurrence for 70 individuals: emission of new leaves, flowering, production of immature fruits, and mature fruits. Floral anthesis occurred during daytime and remained all day until fruit formation. Peak leaf emergence was observed in April, correlating with minimum monthly temperature and mean monthly precipitation. Flowering and green fruit peaked in May and June, respectively, and correlated negatively with all climatic variables. Mature fruits peaked in June, but did not correlate significantly with any of the climatic variables. However, no difference was found between the two sites regarding the timing of phenophases. The spatial distribution pattern of individuals within sites was random. The self-pollination tests showed that the individuals pollinated and fertilized themselves. Our findings allow us to conclude that the phenology of C. scapigera has pronounced phenological seasonality with reproductive peak activities in the drier and colder season, which is congruent with the self-pollination and anemochoric dispersion strategy.

Phytoextraction by harvesting dead leaves: Cadmium accumulation associated with the leaf senescence in Festuca arundinacea

Phytoextraction strategy by harvesting dead leaves provides non-stop phytoremediation and a great saving in disposal cost of hazardous plant residues. This strategy is entirely dependent upon the amount of cadmium (Cd) accumulated in dead leaves. However, it is unknown that whether the leaf Cd accumulation is associated with its senescence and how to regulate its Cd accumulation. This study showed that Cd was preferentially and consistently distributed to and accumulated in the senescent leaves with the new leaf emergence and the old leaf dieback under 75 µM of Cd stress in tall fescue (Festuca arundinacea). Individual leaf monitoring from its emergence to senescence showed that Cd concentration increased exponentially with the leaf life cycle, while leaf biomass decreased gradually after 14 d of leaf emergence. The total amount of Cd accumulated in the leaf showed an exponential increase during leaf senescence, regardless of the leaf biomass loss. Our results demonstrated that leaf Cd accumulation was significantly associated with its senescence and the highest Cd accumulated in dead leaves could be contributed from the continuous Cd input during the leaf senescent process, indicating that further regulatory studies should be focused on the leaf senescence process to achieve higher Cd accumulation and phytoextraction efficiency by harvesting dead leaves.

In Vitro Propagation of Tribulus terrestris with IAA and BAP Concentrations

<p><em>Tribulus terrestris</em> is conventionally propagated using seeds but has limited germination capacity. One approach that can be done for this plant multiplication is in vitro tissue culture. This study was conducted to determine the growth potential of <em>T. terrestris</em> in vitro by the addition of auxin (IAA) and cytokinin (BAP) as growth regulators at several concentrations. The study was conducted at the Laboratory of Plant Physiology and Biotechnology, Faculty of Agriculture, Universitas Sebelas Maret Surakarta from February to December 2017. The experiment employed factorial Completely Randomized Design (CRD) method with 2 factors, namely IAA concentration (0 ppm, 0.1 ppm, 0.2 ppm, 0.3 ppm), and BAP concentration (0 ppm, 0.3 ppm, 0.5 ppm, 0.7 ppm). The observed growth parameters were shoot emergence time, leaf emergence time, root emergence time, number of leaves, and number of roots. Data were analyzed using analysis of variance followed by DMRT with a 95% confidence level. The results showed that the addition of IAA only affects leaf emergence time, while the addition of BAP had a significant effect on the leaf emergence time and number of leaves. The interactions between IAA and BAP had a significant effect on leaf emergence time.</p><p> </p><p align="left">Keywords: explant; plant growth; tissue culture.</p>

Bowen ratio and daily temperature range thresholds: Are they signals of transient seasons?

&lt;p&gt;The winter into spring and the summer into autumn transition seasons can last several weeks. Leaf emergence in midlatitude climates decreases the ratio of sensible (&lt;em&gt;H&lt;/em&gt;) and latent heat (&lt;em&gt;LE&lt;/em&gt;) fluxes - the Bowen ratio (&lt;em&gt;B&lt;/em&gt;). &amp;#160;Because there are many more surface climate stations than flux-measuring sites, researchers seek to link the state variables at standard climate station heights to the leaf development.&amp;#160; Schwartz (1996) found out that, during the midlatitude onset of spring, the DTR trend rapidly increases for several weeks and then levels off. &amp;#160;Adopting an alternate approach, Fitzjarrald et al. (2001) linked changes in &lt;em&gt;H&lt;/em&gt; and &lt;em&gt;LE&lt;/em&gt; to &lt;em&gt;B &lt;/em&gt;to the state variable daily change tendencies. This approach is based on assuming that the surface climate alters as a small fraction of the surface fluxes converge on average into the lower atmosphere.&lt;/p&gt;&lt;p&gt;Schwartz&amp;#8217; approach has the advantage of not requiring information from directly-measured fluxes, but station&amp;#8217;s representativeness during the daytime (&lt;em&gt;T&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt;) greatly exceeds the area that the &lt;em&gt;T&lt;sub&gt;min&lt;/sub&gt;&lt;/em&gt; would describe. What&amp;#8217;s more, daytime cloudiness depreses &lt;em&gt;T&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt; but nocturnal cloudiness enhances &lt;em&gt;T&lt;sub&gt;min&lt;/sub&gt;&lt;/em&gt;. The Fitzjarrald et al. approach requires long-term day-to-day averages to determine the times of the year when the surface state variables identify the consequences of leaf emergence.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Here we seek to refine methods to relate plant characteristics to surface climate state, with emphasis on the spring transition at Harvard Forest (HF, MA, USA). At HF, J. O&amp;#8217;Keefe kept a careful log of significant phenological events (Klosterman et al., 2018). The transition to the &amp;#8216;growing season&amp;#8217; begins with bud break (mid-April), ending with nearly fully leafed crowns (&quot;95%&quot;) in most species by mid-May.&lt;/p&gt;&lt;p&gt;We revisited the HF data and found that DTR, from the start of spring transition until the end of autumn, changes along with daily sensible heat flux changes, particularly during the period from sunrise until the daily maximum air temperature occurs. Since the seasonal course of daily temperature &lt;em&gt;T&lt;sub&gt;d &lt;/sub&gt;&amp;#160;&lt;/em&gt;(&amp;#176;C) follows the latent heat flux trend, we &lt;em&gt;normalized&lt;/em&gt; the DTR (DTR/&lt;em&gt;T&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt;) and found that DTR/&lt;em&gt;T&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt; &amp;#8776; 1 approximately at budbreak and again at &quot;95%&amp;#8221;. When the DTR next approaches &lt;em&gt;T&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt;&lt;sub&gt;,&lt;/sub&gt; the autumn transition is beginning. We use the METAR data to identify cloudy/clear periods and assess the sensitivity of DTR to this effect.&lt;/p&gt;&lt;p&gt;We examined the utility of using DTR/&lt;em&gt;T&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt; ratio as an indicator of spring and autumn transition, exploring &amp;#160;temperature measurements and phenological observations from the HF and PIS network (Lalic et al., 2020). Preliminary results indicate that this approach can identify significant effects of leaf state on local surface climate without the need for averaging over a decade or longer.&lt;/p&gt;&lt;p&gt;Fitzjarrald et al., 2001, 1175/1520-0442(2001)014&lt;0598:CCOLPI&gt;2.0.CO;2.&lt;/p&gt;&lt;p&gt;Klosterman et al., 2018, 1007/s00484-018-1564-9&lt;/p&gt;&lt;p&gt;Lalic et al., 2020, 1007/978-3-030-37421-1.&lt;/p&gt;&lt;p&gt;Schwartz, 1996, 1175/1520-0442(1996)009&lt;0803:ETSDID&gt;2.0.CO;2&lt;/p&gt;

Comparative analysis of the efficacy of selected gametocide agents in sorghum (Sorghum bicolor [L.] Moench)

A new generation of chemical hybridization agents (CHAs) or gametocides has shown potential to induce male sterility in predominantly self-fertilizing crops, including sorghum (Sorghum bicolor [L.] Moench). There is a lack of information on the relative efficacy of the various available CHAs for large-scale application in plant breeding programs. Therefore, the objective of the present study was to compare the relative effectiveness of three selected CHAs to induce male sterility in sorghum under a controlled environment for hybridization. Foliar applications of three CHAs and a control (ethrel, trifluoromethanesulfonamide [TFMSA], ethyl 4-fluorooxanilate [E4FO] and distilled water [control]) were tested using three grain sorghum genotypes (ICS-1, ICS-2 and ICS-3) in two seasons. The 24 treatment combinations consisting of 4 levels of CHAs, 3 sorghum varieties and two seasons were laid out using a randomized complete block design with three replications. Data on pollen sterility, pollen diameter, plant height, and panicle height were collected and analyzed. Results showed that the CHAs had significant (p<0.05) differences for efficacy of inducing male sterility in sorghum. Ethrel at a dose of 1 gl-1 induced the highest pollen sterility (98% in both seasons) but was highly phytotoxic with at least 60% mortality in the test population in both seasons, making it unsuitable for practical application. TFMSA (2 mg per plant) and E4FO (1 gl-1) d induced 93% male sterility with minimal phytotoxic effects (20 to 30%). Application of either TFMSA at 2mg per plant after flag leaf emergence or 1gl-1 of E4FO at panicle initiation can be used to successfully induce male sterility in sorghum under greenhouse conditions

Transcriptional Changes of Cell Wall Organization Genes and Soluble Carbohydrate Alteration during Leaf Blade Development of Rice Seedlings

Plant cell walls have two constituent parts with different components and developmental stages. Much of the mystery concerning the mechanisms of synthesis, decomposition, modification, and so forth, has been resolved using omics and microscopic techniques. However, it still remains to be determined how cell wall development progresses over time after leaf emergence. Our focus in the present study was to expand our knowledge of the molecular mechanisms associated with cell wall synthesis in rice leaf blade during three distinct stages (sink, sink-to-source transition, and source). The RNA-seq, quantitative reverse transcription PCR (qRT-PCR) and carbohydrate concentrations were evaluated using developing fifth leaf blades harvested at different time points. The results revealed that some of the essential genes for the primary cell wall (PCW) were highly upregulated in the sink-to-source transition compared to the sink stage, whereas those essential to the secondary cell wall (SCW) displayed relatively higher levels (p < 0.05) during the source stage. The concentrations of soluble carbohydrates differed via type rather than stage; we observed higher monosaccharides during the sink stage and higher di- and oligo-saccharides during the sink-to-source transition and source stages. In conclusion, our findings suggest that the transcriptional regulation of plant cell wall biosynthesis genes are both synchronistic with and independent of, and directly and indirectly governed by, the abundance of soluble carbohydrates in the developing leaf blade, and, finally, raffinose is likely to play a transport role comparable to sucrose.

The penalty of spring frost damages from earliest to latest possible leaf-out timings in temperate forest trees

&lt;p&gt;The timing of a tree's leaf emergence represents a trade-off between maximising competition for resources (e.g. light, nutrients) and avoiding freezing damage. Global warming has significantly advanced the date of the last frost events in temperate zones, but in parallel has also shifted the onset of vegetation in spring over the last decades. Thus, the risk of frost damage to plants has not necessarily decreased, depending on geographical location and species. In this study we aim to assess the overall impact of frost damage for saplings vitality. We used saplings of 4 temperate, deciduous tree species (&lt;em&gt;Prunus avium, Carpinus betulus, Quercus petrea &lt;/em&gt;and&lt;em&gt; Fagus sylvatica&lt;/em&gt;) and artificially altered the leaf-out date by applying a warming or cooling treatment before the natural leaf-out to reflect the whole range of possible leaf-out dates. Once leaves emerged, we simulated a natural frost event, damaging all or half of the new leaves. We then analyzed how fast the different species recovered depending on leaf-out timing in terms of recovery time (time until second flush), growth (biomass and heigth) and non-structural carbohydrate reserves (NSC) in relation to non-frozen control plants. By&amp;#160; quantifying the penalty of frost damages in late spring this experiment aims to specify the risk of a species&amp;#8217; strategy to time spring phenology.&lt;/p&gt;

Germination and Seed Vigour of Indigenous Bean (Phaseolus Vulgaris) Genotype in Nepal

Bean is an important vegetable crop of Nepal but farmers of Jumla district of Nepal are experiencing low productivity, probably due to poor germination. Keeping these points in view, a study was conducted to determine the germination and seed vigour of various indigenous beans genotype of Jumla district during February to March, 2018. The promising lines of Jumli beans namely KBL-3, KBL-2, PB0002, PB0001, KBL-1 and farm saved KBL-3 were used under study. The experiment was laid in completely randomized design (CRD) with four replications and six treatments namely T1 = KBL-3, T2 = KBL-2, T3 = PB0002, T4 = PB0001, T5 = KBL-1 and T6 = Farm-saved KBL-3. Significant differences were observed in germination percentage, speed of germination, seed vigourindex and true leaf emergence among different lines of Jumli beans .The highest germination percentage (96%), seed vigour index (1367) and speed of germination (1.763) was found in the variety of KBL-3 whereas the lowest germination percentage (69%), seed vigour index (947) and speed of germination (0.968) were found in the variety of KBL-1. Days to true leaf emergence was found shortest in the KBL-3 (23.50) and longest in the farm saved KBL-3 (30.25). KBL-3 pureline of Jumli bean was found to be highly responsive to seed germination and vigour characteristics. Thus, it would be better to suggest the indigenous bean growing farmers of Jumla district to cultivate KBL-3 for better germination and seed vigour. SAARC J. Agri., 18(2): 67-75 (2020)