Seedling Shoot Dry Weight Research Articles

Microbial Biostimulants and Seaweed Extract Synergistically Influence Seedling Growth and Morphology of Three Onion Cultivars

Onion (Allium cepa L.), a globally cultivated vegetable crop, possesses a shallow root system, making it vulnerable to abiotic stresses. The increasing frequency of extreme weather events in recent years necessitates sustainable solutions to enhance onion growth. Biostimulants offer a promising and accessible approach to promote onion growth and quality in an environmentally friendly and sustainable manner. This study investigated the effects of nine commercial microbial biostimulants (LALRISE Mycorrhizae, LALRISE Bacillus, Mighty Mycorrhizae, MycoApply, Spectrum DS, Spectrum Myco, Spectrum, Tribus Original, and Tribus Continuum) and one non-microbial commercial biostimulant (Kelpak—seaweed extract) on the seedling growth of three onion cultivars: Carta Blanca (white), Don Victoro (yellow), and Sofire (red). The results indicated that biostimulants did not significantly affect onion seed germination, but germination rates did vary among the onion cultivars. These cultivars also exhibited significant morphological and biomass differences, with principal component analysis revealing a more obvious effect on root growth compared to shoot growth. Kelpak seaweed extract increased the plant height, leaf area, and shoot fresh weight and dry weight of onion seedlings but decreased the root-to-shoot dry-weight ratio. The effects of microbial biostimulants on onion seedling growth depended on both the onion cultivar and Kelpak seaweed extract. In general, LALRISE Mycorrhizae, Mighty Mycorrhizae, Spectrum Myco, Spectrum DS, and Tribus Continuum exhibited positive effects on seedling growth in certain onion cultivars. Furthermore, the benefits of microbial biostimulants were amplified when combined with Kelpak seaweed extract application. These findings suggest a synergistic interaction between microbial and non-microbial biostimulants, leading to enhanced onion seedling growth. Further research is required to evaluate the long-term effects of these biostimulants on onion plant growth after transplanting to fields.

Exogenous Streptomyces spp. enhance the drought resistance of naked oat (Avena nuda) seedlings by augmenting both the osmoregulation mechanisms and antioxidant capacities.

Drought is a major obstacle to the development of naked oat industry. This work investigated mechanisms by which exogenous Streptomyces albidoflavus T4 and Streptomyces rochei D74 improved drought tolerance in naked oat (Avena nuda ) seedlings. Results showed that in the seed germination experiment, germination rate, radicle and hypocotyl length of naked oat seeds treated with the fermentation filtrate of T4 or D74 under PEG induced drought stress increased significantly. In the hydroponic experiment, the shoot and root dry weights of oat seedlings increased significantly when treated with the T4 or D74 fermentation filtrate under the 15% PEG induced drought stress (S15). Simultaneously, the T4 treatment also significantly increased the surface area, volume, the number of tips and the root activity of oat seedlings. Both T4 and D74 treatments elicited significant increases in proline and soluble sugar contents, as well as the catalase and peroxidase activities in oat seedlings. The results of comprehensive drought resistance capacity (CDRC) calculation of oat plants showed that the drought resistance of oat seedlings under the T4 treatment was better than that under the D74 treatment, and the effect was better under higher drought stress (S15). Findings of this study may provide a novel and effective approach for enhancing plant defenses against drought stress.

Impact of magnetized water on seed germination and seedling growth of wheat and barley

Wheat and barley are considered as a world's number one in nutritional basis of humans and animals worldwide. The effects of magnetized water on the seed germination and seedling growth of wheat (Triticum durum L. c.v. umqais) and barley (Hordeum vulgare L. c.v. athruh) were investigated. Static magnetic field (MF) of 0.15 T strength on four types of water; Tap Water (TW), Deionized Water (DIW), Distilled Water (DISW), and Rain Water (RW) were examined. Triplicate groups of wheat and barley seeds with triplicate of water types were studied under the influence of magnetized water with different time intervals. The magnetized (DIW) significantly increased the seedling root fresh weight in wheat and the germination rate in barley, while magnetized (TW) increased the seedling shoot fresh weight and seedling root fresh weight in wheat but decreased the seedling shoot dry weight and vigor index-II in barley. Significant reduction in barley seedling shoot length and vigor index-I was observed with magnetized (DISW). Moreover, it is shown that in the presence of a static magnetic field the water pH, Electrical Conductivity (EC), and Total Dissolved Solids (TDS) were significantly affected. In addition, the pH of DIW, DISW, and (RW) increased by 40%, 26%, and 1.1% respectively, after 25 min of exposure to MF, and the maximum increase occurred between 20 min and 25 min for DIW, DISW. A similar increase was observed in EC and TDS values for DISW. Data indicated that the best retention time for magnetized treated water is 15 min to maintain the pH (5.6–6.5), EC and TDS within the optimal range that are required for successful barley seed germination. These findings highlight the potentials of magnetized water as a novel approach in agricultural, proposing a new avenue to enhance crop growth and productivity, especially in challenging environmental conditions, thereby addressing critical challenges in modern agricultural engineering.

Exploring the potential of sustainable use of reclaimed water to improve crop production in response to contaminants in Vigna radiata

An efficient method of managing agricultural resources is to reuse wastewater for crop irrigation and fertilization. Irrigation using reclaimed water after treatment can have both beneficial and bad environmental effects. The national water strategy of Saudi Arabia considers reclaimed wastewater as an essential component of Saudi Arabia's water resource. It targets to decrease the load of desalination from the Red Sea and use it as a major source of agriculture and industrial use. In Vigna radiata, an experiment is carried out to determine the level of dilution for agricultural application in a seed germination experiment in response to contaminants. The physicochemical properties such as pH, ammonia, turbidity, and chloride values of reclaimed water were higher as compared to the standard guidelines of KSA for using irrigation water. Further, all the studied parameter concentrations decreased with the dilution of tap water. In the seed germination experiment,% germination, relative seed germination, seedling vigor index, etc. were calculated as compared to the control. The results infer that the application of 30 % reclaimed water (T2) enhanced the germination percentage, relative seed germination, and seedling vigor index of V. radiata. The growth of root, shoot, relative shoot growth, fresh weight, and dry weight of seedlings showed that T5 and T6 treatments are not suitable for Vigna cultivation as compared to the control. However, the results suggested that dilution of reclaimed water decreases the concentrations of potential contaminants of emerging concern, heavy metals, pesticides, etc., and makes the water suitable for irrigation.

Integrated physiological, biochemical and transcriptomic analyses reveal the mechanism of salt tolerance induced by a halotolerant Serratia sp. NTN6 in maize

Salt stress is a serious environmental challenge that hinders crop growth and yield. Plant growth-promoting rhizobacteria (PGPR) can successfully and environmentally friendly boost plant development in saline soils. In this study, a halotolerant Serratia sp. NTN6 was isolated from the rhizosphere soil of halophyte Puccinellia tenuiflora and its plant growth-promoting properties were determined. NTN6 inoculation significantly promoted seed germination and seedling growth in maize under salt stress. Shoot height, stem thickness, root fresh weight, shoot fresh weight, root dry weight, and shoot dry weight of salt-stressed seedlings increased by 36.3%, 32.5%, 146.4%, 193.6%, 25.0%, and 109.6%, respectively, after inoculation with NTN6. NTN6-mediated maize salt tolerance was revealed via transcriptomic, physiological, and biochemical analyses. Under salt stress, NTN6 regulated the transcript levels of genes related to chlorophyll synthesis, photosynthesis apparatus, and carbon assimilation pathways, and thus increasing chlorophyll content, Fv/Fm, and net photosynthetic rate; NTN6 reduced the content of O2•–, H2O2, and MDA by regulating the transcripts and activities of antioxidant enzymes; NTN6 affected the transcriptional response of genes involved in ABA synthesis and signaling to salt stress and reduced ABA level. Finally, NTN6 boosted photosynthetic capacity in salt-stressed maize by modulating photochemical activity, C4 pathway and Calvin cycle as well as mitigating reactive oxygen species damage to the photosystem reaction center. This study first investigated the mechanism of Serratia sp.-induced salt tolerance in maize and these findings demonstrate the valuable contribution of halotolerant PGPR strain from halophytes in improving salinity tolerance in non-halophytic crops.

Evaluation of Genetic variability and viability association of eight Mungbean (Vigna radiata L.) varieties under different level of salinity stress

An investigation was carried to study the mean performance, variability and the associations between characters in mungbean. For this study eight mungbean genotypes viz., ADT 2, BM-2002-1, ML 5, AKM 4, Vishal, Vamban, TARM 1 and Utkarsh were used. The experiment was conducted in the Seed Science and Technology (sst) Laboratory and at Pot culture yard, Department of Genetics and Plant Breeding, Faculty of Agriculture, Annamalai University, Annamalai nagar, Tamil nadu from September 2016 to December 2017 with four salt treatments (0, 2, 4 and 6 DSM-1) in ramdomized block design with three replications. Observation were on seven seedling characters such as germination percentage, seedling shoot length, seedling root length, seedling shoot fresh weight, seedling root fresh weight, seedling shoot dry weight, seedling root dry weight and seven quantitative characters such as days to first flowering, plant height, number of branches/plant, number of pods/plant, number of seeds/pod, 100 seed weight and seed yield/plant. Four elite genotypes were found to be superior based on the mean performance namely Utkarsh, TARM 1, Vamban and Vishal among the various levels of salinity.

Genetic diversity in maize at germination and seedling stages under simulated drought conditions

Ninety seven maize (Zea mays) genotypes were evaluated for germination and early seedling characters under PEG6000 (8%) induced drought stress to identify drought tolerant genotypes. Descriptive statistics for percentage of seed germination and abnormal seedling, shoot length, root length, and shoot dry weight, root dry weight, seedling length, seedling dry weight, and vigor index revealed significant variation among the genotypes studied. The percentage of germination and abnormal seedlings varied greatly among the genotypes. The first and second principal components (PC) of PCA results accounted for 73.15 and 26.85% of the total variation of maize genotypes, respectively. The first PC variation consisted primarily of relative seedling shoot dry weight and relative seedling root dry weight. Cluster analysis grouped the genotypes into four clusters. Cluster III genotypes performed better in terms of relative shoot dry weight, relative root dry weight, and number of abnormal seedlings, indicating drought tolerance. Very poorly performance was shown by genotypes in cluster IV, whereas moderately performance was shown by genotypes in cluster II and I. The clusters differed significantly from one another, according to D2 and multivariate analysis. Thirty six genotypes viz. BD-814, BD-810, BD-812, BD-821, BD-815, BD-10015, BD-10238, CML-552, BD-822, BD-826, CML-341, CML-555, CML-591, CML-523, CML-564, BD-817, BD-10018, BD-10240, CML-577, CML-342, CML-556, BD-837, CML-544, BD-827, BD-806, BD-835, BD-840, BD-842, BD-10010, CML-562, BD-10239, BD-10016, CML-593, CML-568 and BD-10234 demonstrated relatively drought tolerance during the germination and early seedling stages might be used in future breeding program. Ann. Bangladesh Agric. (2023) 27 (2): 19-30

Estimation of genetic variability and correlation coefficients of different salinity levels in mungbean genotypes

For this study eight mungbean genotypes viz., ADT 2, BM-2002-1, ML 5, AKM 4, Vishal, Vamban, TARM 1 and Utkarsh were used. Observation were taken on seven seedling characters and 7 quantitative characters. Statistical analysis of the seedling and quantitative characters showed that the PCV was higher than that of GCV for all the characters studied. Highest GCV and PCV were expressed by seedling shoot dry weight at 6 dSm-1 salinity level followed by seedling shoot fresh weight at 6 dSm-1, indicating that variation among the genotypes was highest for these traits. The PCV and GCV values were lowest in germination percentage followed by the shoot length at control. Among the growth characters heritability (broad sense) was found to range from 41.57 % to 100 % in control, while in salinity levels broad sense heritability ranged from 50 % to 100 %. Under control, heritability was high for all characters except for germination percentage, shoot length and plant height. While in salinity condition, it was high for all characters except for number of pods/plant at 6 dsm-1 salinity level. The genetic advance was high in nature only for the germination percentage whereas, the remaining character revealed low GA estimates. The maximum genetic advance in percent of mean (GAMP) was obtained for seedling shoot dry weight followed by seedling root dry weight at 6 dsm-1 and the lowest was for plant height followed by germination percentage at control. The study revealed that all the 14 characters were positively correlated with each other. For all the characters, the genotypic correlation was at higher level than the phenotypic correlation. Four elite genotypes were found to be superior based on the mean performance namely Utkarsh, TARM 1, Vamban and Vishal among the various levels of salinity.

Chitosan modifies the substrate and influences growth of chili seedlings

ABSTRACT The addition of chitosan to soil has been shown to promote plant development, although its actions on the soil and the plants remain unclear. Chili (Capsicum annum L.) seedlings were grown in a greenhouse (20–33°C, 65%–70% RH) on a substrate (topsoil, rice husk charcoal, and coconut coir) at a ratio of 2:1:1 (v/v) amended with 0%, 1%, or 10% (w/w) chitosan powder. Shoot and root dry weights of chili seedlings grown in a substrate containing 1% chitosan exhibited a 2.5-fold and 1.6-fold increase compared to those in 0% and 10% chitosan treatments, respectively. Leaf chlorophyll content was 2.7-fold higher at 20 days after transplanting. Chitosan at 1% improved the cation exchange capacity (CEC), substrate organic matter, and plant essential nutrient absorption (P, K, Ca, Mg, Mn, Cu, and Zn). In contrast, the substrate added with 10% chitosan had a negative effect on chili seedlings, possibly due to an excess of total available nitrogen (1.54% or 1.6 times higher) and organic matter (30% or 1.6 times higher). Seedlings exhibited leaf chlorosis, poor root development, and fewer essential nutrients in tissues than the control and 1% chitosan treatments. Use of 1% chitosan appears to promote chili growth by improving substrate characteristics.

Prediction Model of Pumpkin Rootstock Seedlings Based on Temperature and Light Responses

Temperature and light are the key factors that affect the quality of pumpkin rootstock seedlings’ growth process. Responses to temperature and light are an important basis for optimizing the greenhouse environment. In order to determine the quantitative effects of temperature and light on the growth and development of pumpkin (Cucurbita moschata cv. RTWM6018) rootstock seedlings, relationships between temperature, light, and pumpkin rootstock seedlings growth were established using regression analysis. The results indicated that the daily average temperature had a significant negative correlation with the development time of pumpkin rootstock seedlings, and the shoot dry weight of pumpkin rootstock seedlings increased within a certain range of the daily light integral (DLI). We established a prediction model of pumpkin rootstock seedling quality indicators (hypocotyl length, stem diameter, shoot dry weight, root dry weight, root shoot ratio, and seedling quality index) based on thermal effectiveness and photosynthetic photon flux density (TEP). The coefficient of determinations (R2) of the hypocotyl length and seedling quality index prediction models of pumpkin rootstock seedlings, based on accumulated TEP, were 0.707 and 0.834, respectively. The hypocotyl length and seedling quality index prediction models of pumpkin rootstock seedlings, based on accumulated TEP, were y1 = 0.001 x2 − 0.180 x + 13.057 and y2 = 0.008 x0.722, respectively, which could be used for predicting the growth of pumpkin rootstock seedlings grown under different temperature and light conditions.

Mixed inoculation of dark septate endophytic and ericoid mycorrhizal fungi in different proportions improves the growth and nutrient content of blueberry seedlings

Despite extensive studies on the interaction between dark septate endophytes (DSE) and host plants, little is known about the effects of mixed inoculation of DSE and ericoid mycorrhizal fungi (ERMF) on plants. We assessed the effects of mixed inoculation of five species of ERMF and five species of DSE on soil factors and growth and physiological functions of blueberry (Vaccinium corymbosum L. ‘O’Neal’) seedlings. The strains were isolated from blueberries in several regions of Guizhou Province. The fungi suspension root irrigation method was used to inoculate the seedlings. Six inoculation treatments, i.e. D (Cladosporium cladosporioides), N (Oidiodendron citrinum), D1N1 (D : N, 1:1), D1N2 (D : N, 1:2), D2N1 (D : N, 2:1) and CK (not inoculated) were conducted. Samples were collected two months after inoculation. The mixed inoculation of DSE and ERMF significantly promoted the height, stem diameter, shoot dry weight, total biomass, root activity and total chlorophyll content of the blueberry seedlings and enhanced their absorption capacity to mineral nutrients. The mixed inoculation also improved the activities of soil enzymes such as urease and acid phosphatase. The effect of mixed inoculation was better than that of single inoculation or CK. Combining the analysis results of the membership function, we concluded that D1N2 and D2N1 most significantly promoted the growth of blueberry seedlings. These data provide a basis for the potential application of DSE and ERMF mixed inoculation for promoting the growth of seedlings.

ROLE OF MYCORRHIZA HELPER BACTERIA ON MYCORRHIZAL COLONIZATION AND NEMATODE Pratylenchus coffeae INFECTION

The coffee nursery is susceptible to endoparasitic Pratylenchus coffeae. Application of biological method in the nursery is suggested to control the nematode population and maintain the seedling health. The objectives of this study were to observe the ability of Arbuscular Mycorrhiza Fungi (AMF) Glomus spp. and liquid inoculant of Mycorrhiza Helper Bacteria (MHB) consortium Pseudomonas diminuta and Bacillus subtilis for increasing AMF colonization and reducing the infection P. coffeae in Arabica coffee seedling and their growth. A pot experiment was conducted using a Completely Randomized Block Design with four treatments and five replications. The treatments were Glomus spp. spore inoculation without and with two concentrations of MHB. The control treatment did not receive Glomus spp. and MHB. The seedlings were growing in the greenhouse for three months. The results indicated that Glomus spp. and MHB consortium significantly reduced the nematode total number in soil and roots by approximately 30%; and infection degree of P. coffeae by 50%. The application of Glomus spp. significantly increased root colonization by mycorrhizal fungi, but MHB inoculation did not affect the mycorrhizal colonization. Seedlings treated with MHB had higher shoot length compared to the plant without MHB and control; but the leaves number and shoot dry weight of seedlings were not affected by all treatments. Even though the root fresh weight was reduced after MHB treatment, the lateral roots growth of MHB-treated seedling visually was improved. The experiment demonstrated that MHB was efficient to reduce P. coffeae infection of Arabica seedling.

Ectomycorrhiza-hydrogel additive enhanced growth of Norway spruce seedlings in a nutrient-poor peat substrate

Seedling quality is an important input affecting the outplanted seedling performance. Morphological attributes and association with symbiotic ectomycorrhizal (ECM) fungi belong to influential traits determining seedling quality. In this study, the effect of pre-sowing applied commercial additives Ectovit (containing hydrogel and ECM fungi), Mycorrhizaroots (ECM fungi and nutrients) and Vetozen (natural mineral fertilizer) on the growth and ectomycorrhiza formation of Norway spruce seedlings grown in nutrient-poor pure peat in an open nursery site was assessed. Two-year-old bareroot seedlings were transplanted into containers. No significant growth differences were detected between treatments for 1 + 0 seedlings but the values of growth parameters (root collar diameter; stem height; shoot, root and total dry weight) of Ectovit-inoculated seedlings were significantly higher than those in the other treatments including the control after the second (2 + 0 seedlings) and the third growing season (2 + 1). Root-to-shoot dry weight ratio and number of root tips were distinctly higher after the third year compared to the previous two years but they were not significantly different between treatments. Mycorrhizaroots and Vetozen did not have any significant effect on seedling development. Although the occurrence of treatment-specific ECM morphotype was detected in Ectovit-inoculated seedlings, the high total ECM colonization of roots in all treatments including the control indicated a crucial impact of naturally occurring fungi on ectomycorrhiza formation.

Testing an Allelopathic Effect Arum Cyreniacum on Germination and Growth of Pisum Sativum LTesting an Allelopathic Effect Arum Cyreniacum on Germination and Growth of Pisum Sativum L

Two experiments were conducted (laboratory - pots) at the lab of the biology Department/ Faculty of education/ Omar Al-Mukhtar University/ Al Bayda/ Libya, to aim testing allelopathic effects of aqueous extracts at concentrations of (6, 8 and 10%), adding the Crude powder to soil at a concentration of (3%) of (Tubers-Leaves) Arum cyreniacum on the germination of seeds and development seedlings of Pisum sativum with three replications according to a completely randomized design. The results of the laboratory experiment showed were significant differences in reduction of germination percentage, reduction of radical and plumule lengths between aqueous extracts, compared with control, also, all concentrations caused a clear delay in an average germination time. The results of a pots experiment showed a concentration (3%) reduced the percentage emergence of seedlings, and decrease root and shoot lengths, fresh and dry weights of seedlings. A concentration (3%) caused a decrease of content chlorophyll (a, b), and sodium, an accumulation of carotenoids, potassium and iron, compared to the control. The leaves had the highest inhibition rates compared to the tubers at inhibiting the growth of studied traits. This study concluded that A. cyreniacum has inhibitory effects against germination of P.sativum.

English

Fungal pathogens have been investigated previously for biological control of goosegrass (Eleusine indica), but there is little research on the compatibility of herbicides with fungal pathogen Bipolaris bicolor for control of glyphosate-resistant E. indica. The aims of this study were to 1) examine the in vitro compatibility of Bipolaris bicolor and three herbicides (ametryn, flumiozaxin and sodium chlorate) and 2) determine the efficacy of a combination of B. bicolor and ametryn for inhibiting glyphosate-resistant E. indica biotypes in the greenhouse. Mycelial growth inhibition area was measured after B. bicolor spores were treated with ametryn, flumiozaxin, or sodium chlorate at one-fifth of their recommended rates. The findings showed that ametryn had the lowest inhibitory effect (10%), while flumioxazin and sodium chlorate had 80 and 30% inhibition, respectively, indicating that ametryn is the most compatible herbicide with B. bicolor. E. indica seedlings were then subjected to four treatments, including non-treated plants, at the 3 to 4-leaf stage where T1: negative control plant, T2: one-fifteenth of the recommended dose of ametryn, T3: B. bicolor spore suspension and T4: ametryn plus B. bicolor spore suspension. B. bicolor in combination with ametryn was the most effective treatment for E. indica inhibition one week after treatment. The treatment reduced seedling height, leaf greenness and shoot dry weight by 50 to 94% and caused plant death seven days after treatment. These findings suggest that B. bicolor in combination with ametryn is a viable integrated strategy to control the glyphosate-resistant E. indica biotype. © 2022 Friends Science Publishers

Positive and negative phenotyping of increasing Zn concentrations by Biospeckle Optical Coherence Tomography in speedy monitoring on lentil (Lens culinaris) seed germination and seedling growth

Reliable seed screening that can speedily detect qualities such as dormancy and seed germination can be of great significance in improving plant growth, crop yield, and quality. On the other hand, Optical Coherent Tomography (OCT) has been extensively used as a potential tool in visualizing structures of biological objects, especially the retina. However, its role in visualizing temporal changes that accompany these structures as speckle noise remains relatively underexplored. The present study of biospeckle OCT or bOCT demonstrates the potential of speckles in plant physiological studies. In this paper, the potential of bOCT in speedily investigating the positive and negative phenotyping of increasing Zn concentrations on lentil seed (Lens culinaris) germination and seedling growth were demonstrated. Lentil seeds were exposed to three different Zn concentrations of 0 (control), 5, 10, and 100 mg/L for 24 h, and the structural OCT images were acquired to calculate the temporal fluctuations in the image as a quantity called the average speckle contrast (γ). The average speckle contrast was calculated after 6 h, 12 h, and 24 h of exposure to different concentrations. Statistically significant differences were observed even within 12 h of exposure under all the Zn treatments compared to control. In comparison, the conventional measurements of germination rate, root and shoot lengths, and fresh and dry weights of seedlings took nearly 48 h to observe significant changes. Furthermore, the Zn uptake measurements were significant for all the tested concentrations after seven days of exposure. Further, bOCT results showed a clear concentration dependent effect with 5, 10 mg/L producing positive effects, while a high concentration of 100 mg/L showing a detrimental effect on seed germination and seedling growth. Thus, the current study results imply that bOCT can be used to investigate the positive and negative effects of increasing Zn concentrations on seed germination and seedling growth at an early stage before germination.

Ecological Role of Volatile Organic Compounds Emitted by Pantoea agglomerans as Interspecies and Interkingdom Signals.

Volatile organic compounds (VOCs) play an essential role in microbe–microbe and plant–microbe interactions. We investigated the interaction between two plant growth-promoting rhizobacteria, and their interaction with tomato plants. VOCs produced by Pantoea agglomerans MVC 21 modulates the release of siderophores, the solubilisation of phosphate and potassium by Pseudomonas (Ps.) putida MVC 17. Moreover, VOCs produced by P. agglomerans MVC 21 increased lateral root density (LRD), root and shoot dry weight of tomato seedlings. Among the VOCs released by P. agglomerans MVC 21, only dimethyl disulfide (DMDS) showed effects similar to P. agglomerans MVC 21 VOCs. Because of the effects on plants and bacterial cells, we investigated how P. agglomerans MVC 21 VOCs might influence bacteria–plant interaction. Noteworthy, VOCs produced by P. agglomerans MVC 21 boosted the ability of Ps. putida MVC 17 to increase LRD and root dry weight of tomato seedlings. These results could be explained by the positive effect of DMDS and P. agglomerans MVC 21 VOCs on acid 3-indoleacetic production in Ps. putida MVC 17. Overall, our results clearly indicated that P. agglomerans MVC 21 is able to establish a beneficial interaction with Ps. putida MVC 17 and tomato plants through the emission of DMDS.

Influence of mycorrhizal preparation on seedling growth and Armillaria infestation

The influence of three types of treatment on seedling survival percentage, growth and Armillaria infestation of Fagus sylvatica L. (FAGUS), Abies alba Mill. (ABIES) and Picea abies (L.) H. Karst. (PICEA) seedlings were tested in this study: (i) inoculation with the Ectovit<sup>®</sup> preparation containing ectomycorrhizal fungi (INOCUL), (ii) Ectovit<sup>®</sup> preparation + Conavit<sup>®</sup> fertilizer (INOCUL + FERTILIZ) and (iii) the untreated group (CONTROL). The selected sample contained 100 seedlings per each tree species and treatment type (900 seedlings in total). Besides that, 18 months after planting, 10 living seedlings per each species and treatment (90 seedlings in total) were sampled to evaluate root dry mass and Armillaria infestation. The data were statistically evaluated by frequency analysis, analysis of variance and Kruskal-Wallis test. The overall seedling survival percentage was very low, probably due to extreme drought and high temperatures, with significantly lower results for the ABIES INOCUL + FERTILIZ and PICEA INOCUL + FERTILIZ groups. All tested growth characteristics (seedling height increment, root collar diameter increment, seedling shoot dry weight, root dry mass) were significantly higher in PICEA seedlings. Root collar diameter increment showed significant differences within each species and inconsistent results. Armillaria was detected only in the PICEA CONTROL group as rhizomorphs identified as A. ostoyae. The results suggest that the artificial mycorrhizal preparation can be an efficient method of preventing Armillaria infestation, especially in spruce seedlings.

Effects of high levels of nitrogen and phosphorus on perennial ryegrass (Lolium perenne L.) and its potential in bioremediation of highly eutrophic water.

The conservation and management of rain and water in a city environment are a crucial aspect of sustainability. Sponge cities are a solution for the remediation of excessive water consumption, high pollution, and rainstorm waterlogging in urban areas. Perennial ryegrass (Lolium perenne L.) is a common species and promising bioremediation plant for the construction of sponge cities. It could be useful to purify high nitrogen and phosphorus content in wastewater runoff, but its response to high total nitrogen (TN) and total phosphorus (TP) levels has not been studied. The present study aimed to evaluate the effects of high TN + TP level on seed germination, plant growth, antioxidant response, and assimilation rate of N and P in perennial ryegrass. Compared with the control, treatments with 20 mg/L N + 4 mg/L P (20N4P) significantly decreased germination potential at day 3, but the germination rate at day 10 was similar between all treatments and the control, suggesting that a high TN + TP concentration might delay germination, but not prevent it. Treatment with 20N4P also induced significant withering and decreased shoot length, root length, and dry shoot weight of ryegrass seedlings, compared with the control. Treatments with 80N16P significantly decreased levels of chlorophyll a (Chl-a) and chlorophyll b (Chl-b), demonstrating inhibition of photosynthesis. Compared with the control, treatment with 40N8P increased the carotenoid (Car), malondialdehyde (MDA), and glutathione (GSH) content, which might alleviate oxidative stress induced by high TN + TP concentration. Moreover, high levels of TN + TP (160N32P and 320N64P) significantly reduced the removal capacity of N and P by plants. Overall, the present results provide a theoretical foundation for the development of ryegrass for bioremediation of wastewater during construction of sponge cities.

Shoot and root growth of rice seedlings as affected by soil and foliar zinc applications

The present study investigated how foliar zinc (Zn) application affects seedling growth and Zn concentration of rice grown in a Zn-deficient calcareous soil with different soil Zn treatments. Seeds were sown in soil with five rates of Zn (0, 0.02, 0.1, 0.5 and 5.0 mg kg−1 soil) with and without foliar application of 0.5% ZnSO4. Seedlings were harvested at 35 days and separated into (i) the youngest leaves, (ii) the remaining shoot parts and (iii) roots. In soil with no Zn supply, shoot and root dry weight of the rice seedlings were significantly increased by foliar and soil Zn treatments. Plant growth was not clearly increased in low soil Zn treatments, while at each soil Zn treatment, foliar Zn application promoted growth of plants. Plants with adequate Zn supply had the highest Zn concentrations in the youngest leaf. Foliar Zn spray improved Zn concentration of the new growth formed after foliar spraying which shows that Zn is phloem mobile and moved from treated leaves into youngest new leaves. The results indicate clearly in rice seedlings that shoot growth shows more responsive to low Zn than the root growth. The results obtained in the present study are of great interest for proper rice growth in Zn-deficient calcareous soils but needs to be confirmed in other rice genotypes.