Perlite Substrate Research Articles

Substrate Moisture and Temperature Effects on Limestone Reaction Rate in a Peat-Based Substrate

ABSTRACT Lime reaction rate in a container substrate is influenced by temperature and moisture, which are factors that vary between batches of substrate during manufacturing, storage, and crop production. The effects of temperature and moisture on the duration required to achieve a stable substrate-pH are useful information for substrate companies and growers, as well as a key component when modeling lime reaction over time. The pH of a 70 peat : 30 perlite (by volume) substrate was quantified over time under a range of different storage temperature (1.9 to 33.3°C) and substrate volumetric water content (VWC, 0.168 to 0.568 L of H2O/L of substrate). The lime source was a horticultural dolomitic carbonate limestone screened to the fraction that passed through a 100 US mesh but was retained on a 200 US mesh (0.075–0.15 mm) incorporated at 2.67 g·L−1 of substrate. Experiments provided two data sets for calibration and validation. Lime reaction rate increased with increasing substrate temperature and substrate moisture level. The duration required to reach a target substrate-pH value of 6.0 was used to indicate 90% of maximum pH effect from lime. Duration varied from 4 days with the combined high temperature (20.6 and 33.3 °C) and high VWC (0.468 and 0.568 L H2O/L of substrate) to 53 days with low temperature (1.9 °C) and low VWC (0.168 L H2O/L of substrate) for the calibration data set. At an example low VWC of 0.168 L of H2O/L of substrate, the duration required to reach substrate-pH 6.0 at 1.9, 7.8, 10, 20.6, and 33.3°C was 53, 38, 34, 23, and 17 days, respectively. Similarly, if the temperature was held constant at 33.3°C, reducing VWC from 0.568 L H2O/L to 0.128 L H2O/L would decrease lime reaction rate from 100% to 21%, requiring five times the duration to reach an equilibrium pH. Results can be used to compare the relative effects of moisture and temperature on lime reaction rate for substrate manufacturers and growers.

Life cycle assessment of a high-tech vertical decoupled aquaponic system for sustainable greenhouse production

IntroductionAquaponics provide multiple benefits due to the simultaneous yield of vegetables and fish, however they are characterized by increased greenhouse gas emissions owing to intensive production system. The most appropriate method for quantifying the environmental effects of these systems is Life Cycle Assessment with which the identification of hotspots and the suggestion of improved production plans can be achieved. The purpose of the present study was to evaluate the environmental impact of a pilot high-tech aquaponic system utilized for the simultaneous production of baby lettuce and rocket as well as rainbow trout, in indicators such as Global Warming Potential.Materials and methodsTo achieve this goal, data on inputs and outputs were collected from 12 case studies that were implemented, combining different fertilizer treatments, substrate choices, plant species cultivated and water source provision. Life Cycle Assessment was performed using SimaPro v.9.4.0.2 software.ResultsThe results showcase that the optimal case studies include the cultivation of baby lettuce and rocket in perlite substrate using wastewater from fish and partial use of synthetic fertilizers. Indicatively, Global Warming Potential of these cases was calculated at 21.18 and 40.59 kg CO2-eq/kg of vegetable respectively. The parameter with the greatest impact on most of the environmental indicators was electricity consumption for the operation of the oxygen supply pump for the fish tanks, while greenhouse infrastructure had the greatest impact in Abiotic Depletion and Human Toxicity impact categories. In an alternative production scenario tested where renewable energy sources were used, system impacts were reduced by up to 50% for Global Warming Potential and 86% for Eutrophication impact. The results of this study aspire to constitute a significant milestone in environmental impact assessments of aquaponic production systems and the adoption of more sustainable farming practices.

АДАПТАЦИИ РЕГЕНЕРАНТОВ HUMULUS LUPULUS L. К УСЛОВИЯМ EX VITRO

The purpose of the study is to develop a scheme for two-stage adaptation of regenerated plants of common hop (Humulus lupulus L.) to ex vitro conditions using a hydroponic installation. Objectives: to study the influence of the method of fixing hop regenerants in a hydroponic system; to determine the duration of the adaptation stage in hydroponics; to select the substrate composition at the second stage of adaptation. The object was a sterile culture of common hop of three varieties: Tsivilsky, Flagman and Taurus, after completion of the in vitro rooting stage on a nutrient medium according to the Murashige-Skoog recipe (MS) containing glucose (20 g/l) and IBA (0.5 mg/l). The duration of the adaptation stage of hops rooted in vitro in a tidal-type hydroponic system was determined, identified by the stable maintenance of turgor by leaves and active growth of shoots – 18–21 days. The influence of the method of fixing hop regenerants in a hydroponic system was studied: the use of seedling cassettes with a substrate of perlite and vermiculite (1 : 1) showed a 25 % higher survival rate of plants compared to substrate-free cuvettes with liners made of polyethylene film. It was shown that under hydroponic installation conditions, regardless of the fixation method, the height of the shoots increased by 36.0–48.3 %. The root system of the samples adapted in cassettes with substrate was better developed and was characterized by a large number of 2nd order roots with a length of at least 4 cm. The subsequent stage of adaptation in most peat-containing substrates ensures 100 % survival and the production of high-quality planting material. Recommendations for growing hop planting material after two-stage adaptation are presented.

Optimization of the in-vitro culture protocol of Haworthiopsis viscosa and Haworthia truncata var. truncata

This study was conducted to optimize the in vitro culture of Haworthiopsis viscosa and Haworthia truncata var. truncate. The full and half concentration of Murashige and Skoog (MS) and Gamborg (B5) after the disinfection of the explants was used to determine the suitable medium culture. The effect of the different concentrations of 6-benzyl aminopurine (BA) and Kinetin (Kin) (0, 1, 2, 3 and 6 mg/L) was investigated on the percentage of regeneration, callus formation and the number of seedlings regenerated. The different concentrations of indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA) (0, 0.5, 1 and 1.5 mg/L) were used to investigate the seedlings rooting. Finally, the cocopeat + perlite, the sand +perlite and the vermicolit +perlite substrates were studied to determine the suitable substrate for compatibility. The results show that the use of MS culture medium at complete concentration was more successful than the other treatments and increased the regeneration and seedling percentage in both species. Also, the use of BA at a concentration of 1 mg/L (H. truncata var. truncate) and at a concentration of 3 mg/L (H. viscosa) increased the percentage of regeneration and the number of regenerated seedlings significantly and the regenerated seedlings had a very good quality. The rooting of seedlings in both studied species was the highest at 1 mg/L IBA. The use of NAA in the culture medium produced roots that stuck together and were fragile in some cases, which was not suitable for the compatibility. By comparing different substrates, it was found that the use of cocopeat + perlite increased the seedling compatibility percentage to more than 95% in both species.

The effect of grafting on vegetative and reproductive traits of tomato

Relevance. Tomato (Solanum lycopersicum L.) is one of the most important vegetables in the world. Every year the number of identified viruses and diseases increases, infection with which causes significant crop losses and significantly worsens the quality of agricultural products, especially in tomatoes. Material and methods. In the present study we compared the growth of the vegetative and reproductive traits of tomato plants ‘Dokia’, ‘TY Red 250’ and ‘Pilabi’ grated onto bacterial wilt (caused by Ralstonia solanacearum) and Fusarium wilt (Fusarium oxysporum) diseases tolerant rootstock “Spider” (Takii seed, Japan). The non-grafted (control - CT) and grafted tomato plants (GR) were transplanted on 4 March of 2021 to the four season (vinyl) greenhouse on substrate perlite (mixture of perlite no. 1 and no. 3) and cultivated until September 20. Results. The results showed that responses of the tomato cultivars to grafting combination was different, where agronomical traits depends on the each cultivar’s features can be ranged. The reduction of the values of stem diameter (SD), leaf length and width (LW), fresh fruit weight (FFW), fruit diameter (FD), fruit pericarp thickness (FPT) and fruit hardness (FH) with aging of plants and rising ambient temperature was detected. However, fruit soluble solids among all cultivars regardless of treatments were slightly increased. The index of fruit yield per truss (FYT) significantly decreased among all cultivars after 10th truss regardless of the treatments when the daily temperature increased from July to August. In grafted tomato ‘TY Red 250’ were identified the highest fruit yield per plants (FYP) than in CT plants, whereas in other tomatoes did not found similar differences between CT and GR plants.

Comparison of Methods to Determine Nutrient Uptake of Tomato Grown in Free-Draining Perlite Substrate—Key Information for Optimal Fertigation Management

Two methods were compared to determine crop nutrient uptake by tomato crops in free-draining perlite substrate. They were the nutrient balance method (applied minus drained) and the dry matter method (DM) (nutrients in plant material). Uptake of N, P, K, Ca, Mg, and S was determined using both methods, in three consecutive tomato crops planted in the same perlite. Nutrient uptake determined using the balance method was consistently higher than with the DM method. Relative differences (balance minus dry matter, with respect to the DM method) were N: −1 to 16%, P: 27–45%, K: 14–46%, Ca: 17–87%, Mg: 28–111%, and S: 15–65%. There was a clear tendency for the difference between the methods to reduce with successive crops. The differences between the methods were reduced when the measured retention of nutrients in the perlite substrate and estimated nutrient retention in roots (using a model) were included. However, these data did not explain all of the observed differences between the two methods. Various retention and loss processes may explain the differences. The results suggest that the DM matter method estimates nutrient uptake by the crop, and the balance method estimates nutrient consumption by the cropping system.

Response of leaf photosynthesis, chlorophyll content and yield of hydroponic tomatoes to different water salinity levels.

Tomato (Solanum lycopersicum L.) is an important vegetable crop that grows easily under controlled conditions, such as in greenhouses and hydroponics. To overcome freshwater scarcity, researchers are searching for alternatives to groundwater sources such as desalinated water (saline water) for irrigation. High salinity in irrigation water alters physiological functions and crop development, thereby reducing the yield. Best management practices and the use of grafted tomato plants on salt-tolerant rootstocks can alleviate salinity stress. The present study was conducted to address the impact of salinity stress on leaf transpiration (Tr), stomatal conductance (gs), photosynthesis (Pn), leaf chlorophyll content, proline content, and yield of hydroponically cultivated tomato plants. Saline (NaCl) water was used for the preparation of nutrient solution with three salinity levels, electrical conductivity (EC, dS m-1) of 2.5 (control), 6.0, and 9.5. Three commercial tomato cultivars (Valouro-RZ, Ghandora-F1, and Feisty-Red) were used. Both self-rooted plants and plants grafted onto Maxifort rootstocks were transplanted onto a perlite substrate. The recorded data revealed that all studied cultivars were critically affected by higher salinity (≈ 9.5 dS m-1) compared to low (≈ 2.5 dS m-1) and medium (≈ 6.0 dS m-1) salinity levels. The Variations in Tr, Pn, gs, chlorophyll content of leaf, and yield between medium and high salinity trials were reported at 3%, 5%, 9%, 5%, and 7.1%, respectively, whereas no significant differences were observed between low and medium salinities. However, at medium salinity levels, grafted plants performed better in photosynthesis than non-grafted plants. This is due to the accumulation of leaf proline, which maintains osmotic regulation and photosynthetic activity by preventing cell damage at medium salinities. Hence, this study confirmed the use of saline water for growing tomatoes under hydroponic conditions up to an EC of 6.0 dS m-1 including the EC of nutrient fertilizers.

Coconut Juice Enhances Rooting and Leaf Essential Oils of Juniperus sabina L. Cuttings

Juniperus sabina L. (J. sabina L.) represents a compelling forest species due to the presence of metabolites in its leaves, which possess diverse applications in the fields of cosmetics, pharmaceuticals, and medicine. However, the species presents difficulties with regard to natural regeneration. This research aimed to improve the propagation conditions of J. sabina by using cuttings to enhance both the rooting percentage and essential oil (EO) content in the leaves. To do this, sampled cuttings underwent pretreatment with four different doses of coconut juice (25%, 50%, 75%, and 100%) within four substrates or rooting media, namely perlite, mixed substrate, pumice, and perlite–cocopeat. The study was carried out over the course of all four growing seasons to examine the impact of harvesting time as well. The best results for rooting were observed with the pretreatment of coconut juice at 25% in spring and in the substrate of perlite–cocopeat (37.10% rooting). The coconut juice also significantly increased the percentage of EOs in spring (0.82% of essential oil yield). Beta-pinene was the essential oil component with the highest representation (34.7% in fall), whereas in the spring, the best season to collect cuttings, the dominant component was nerodiol. Our study can contribute to the planning of culture systems using cuttings and to the control of the production of EOs from the leaves of J. sabina.

First Report of Diaporthe fruit rot and stem canker of hydroponic cucumber caused by Diaporthe sp. in the United States.

Multiple Diaporthe spp. cause root and fruit rots or stem lesions on Cucumis spp.: D. cucurbitae, D. melonis, D. longicolla (syn. D. eres), D. pterocarpi, D. sclerotioides, D. sojae, and D. ueckerae (Broge et al. 2020; Fukada et al. 2018; Udayanga et al. 2012, 2015). From May-August 2021, cucumbers (Cucumis sativus) 'Katrina' and 'Alcazar' were grown in a 24-plant, commercial Bato bucket system with rockwool blocks on a perlite substrate in a research greenhouse in Wooster, Ohio. At maturity, plants collapsed rapidly from stem lesions without foliar chlorosis (25% of 'Katrina' and 17% of 'Alcazar'). Lesions were 7.5 to 15 cm in length, tan to golden-brown with black pycnidia and located 5 to 15 cm above the crown. Stems shredded easily with vascular discoloration around the lesion. Two identical fungal strains were isolated on ½ acidified potato dextrose agar (APDA) following surface disinfestation with 0.6% sodium hypochlorite for 30 s and sterile water rinse. Fungal cultures were floccose, white to tan mycelia with pycnidia. Oblong, elliptical, biguttulate, aseptate alpha conidia were observed with mean dimensions: 8.0 µm (5.2-9.8 µm) by 3.1 µm (2.5-3.8 µm) on ½ APDA and 9.8 µm (6.6-12.4 µm) by 3.0 µm (1.9-5.3 µm) on petioles. On prune extract agar, beta conidia mean dimensions were: 19.7 µm (12.0-27.7 µm) by 1.2 µm (0.8-1.8 µm). Fungal DNA was amplified and sequenced bidirectionally with ITS (ITS4/ITS5), CAL (CAL228F/737R), HIS (CYLH3F/H3-1B), TEF1 (EF1-728f/EF1-986R), and TUB2 (Bt1a/Bt1b) primers (Carbone and Kohn 1999; Glass and Donaldson 1995) (GenBank: OP265712-13, OP288460-65, OQ418506-07). Based on a maximum likelihood phylogenetic tree of concatenated genes, this novel Diaporthe sp., most closely related to D. stewartii, has not been reported on Cucumis spp. Strains were deposited in the USDA-ARS Culture Collection (NRRL# 64461-62). Koch's postulates were conducted in a greenhouse with mean day temperature of 25°C and 12 hr supplemental lighting. One-month old cucumbers 'Katrina,' grown in rockwool cubes (5 plants per isolate) and potting mix (6 plants per isolate), were inoculated with a one-week-old culture of either strain. The second true leaf was cut and a pipette tip containing an inoculated plug of ½ APDA was placed on the remaining petiole (Mathew et al. 2018). Non-inoculated ½ APDA was used for controls. Plants were tarped for 24 hours to increase humidity and pipette tips removed after one week. After two weeks, petioles were shrunken, tan to golden brown with pycnidia. After 3-4 weeks, stem lesions matching those above were observed on inoculated plants, and plants collapsed. For fruit rot, three Beit Alpha cucumbers were rinsed with tap water, dried, a 5 mm plug was removed from the fruit and replaced with a 5 mm plug of one-week-old fungus on ½ APDA. After 3 days, fruits were water soaked and soft. For root rot, two plates of one-week-old cultures were macerated in 500 mL of sterile water and mixed with 1500 mL of vermiculite. Two seeds of cucumber 'Katrina' were planted into three reps of each isolate and control. All control seeds germinated, but all inoculated seeds experienced pre- or post-emergence damping off. No symptoms were ever observed on any controls. Fungi were isolated from all inoculated tissues as described above. Based on morphology, Diaporthe sp. was isolated from all inoculated plants but never from controls. This Diaporthe sp. may be a new constraint to hydroponic cucumber production, but incidence needs to be determined globally.

Post-aseptic adaptation and ex vitro propagation of Ukrainian cultivars of Paulownia Sieb. et Zucc.

Plantation forestry using highly productive and fast-growing plants involves the use of high-quality improved planting material for genetic constancy, which is solved by microclonal reproduction. However, the high survival rate and stability of plants obtained in vitro are realised as a result of post-aseptic adaptation of regenerants. Therefore, the research aims to improve the survival techniques of paulownia regenerants of the Ukrainian varieties “Feniks” and “Enerdzhy” ex vitro. The study was conducted in December 2021 on the Ukrainian paulownia varieties “Feniks” and “Enerdzhy”, cultivar “Feniks”. The survival rate, development of regenerants, and their damage by facultative saprophytic pathogens differed on substrates of organic (Eco Plus, La Flora, Jiffy, coconut peat, cotton wool) and mineral (vermiculite, perlite, sand) origin. The biological products “Rise P” and “Prestop” proved to be effective for the control of pathogenic microorganisms on substrates of organic origin. The technological feasibility of using perlite substrate is substantiated. The pathophysiology of ex vitro regenerants of paulownia under Fusarium is described. The thickness of the films used for sheltering influenced the regeneration, engraftment, microbial damage, and temperature of the wet chambers. Growing regenerants with covering films of different thicknesses showed a high survival rate in the variants with stretch films of 10 and 23 µm thickness. In the case of using polyethene films with thicknesses of 60, 80 and 100 µm, a sharp increase in temperature was observed, which was 48, 53 and 650C, respectively. At these high temperatures, most of the regenerants died, after which they were colonised by facultative saprophytes, and the tissues were completely macerated within two days. The optimal ratio of juvenility reduction and the acquisition of adaptive traits is characteristic of the second, third and fourth generation ex vitro. The expediency of propagation by stem cuttings up to the fourth generation, which preserves the regenerative ability of shoot cuttings, was substantiated. The practical results of the research are a protocol for growing paulownia plants in vitro and ex vitro on different types of substrates for use by institutions engaged in paulownia propagation

The Influence of Vibration and Moisture Content on the Compactness of the Substrate in Nursery Container Cells Determined with a Multipenetrometer

An important problem of container nurseries is ensuring equal and favorable growth conditions for cultivated plants. This can be achieved by ensuring the physical parameters of the substrate used to grow seedlings in individual cells of the container are similar. The nursery container is filled with a specially composed substrate through an automated line. Quickly controlling the parameters related to the quality of substrate filling presents a significant problem, as it requires the ongoing correction of the filling module settings (e.g., extending the vibration time or changing the vibration amplitude). To address this issue, it would be helpful to determine the compactness of the substrate, which can be easily measured using a penetrometer. This paper presents a prototype automated station, known as a multipenetrometer, designed for the simultaneous testing of compactness in 15 selected container cells. The prototype was put to the test at the Nursery Farm in Sukowo, where two types of polystyrene containers (V150—650/312/150 mm; 74 cells; and 0,148 cm3 cell volume and V300—650/312/180 mm; 53 cells; and 0.275 cm3 cell volume) were filled with peat–perlite substrate on the Urbinati Ypsilon automated line. This study investigated the influence of substrate moisture (two levels—70 and 75%) and vibration intensity (two levels—8 and 12 G) of the vibrating table on its compactness within the individual cells of the nursery container. The results indicated that with an increase in substrate moisture and vibration intensity, the compactness of the substrate increased, and the variation in compactness between individual cells decreased. Notably, the V300 containers, with a larger cell volume (265 cm3), experienced a higher level of change compared to the V150 containers (145 cm3). Despite the use of substrate compaction techniques based on the experience of line operators filling containers, the coefficient of variation between the compactness of the substrate in individual cells of the container remained at 30%. Based on the findings, it was confirmed that the optimal parameters for filling V150 and V300 containers with peat–perlite substrate on the Urbinati line, at a filling capacity of approximately 400 containers h−1, are a moisture content of around 75% and a maximum vibration intensity of 12 G.

Water Availability in Pumice, Coir, and Perlite Substrates Regulates Grapevine Growth and Grape Physicochemical Characteristics in Soilless Cultivation of Sugraone and Prime Cultivars (Vitis vinifera L.)

Table grape production in soilless cultivation under a controlled environment is a promising solution that addresses many of the challenges of grapevine cultivation, such as factors affecting the quantity and quality of table grape production, cultivation cost, pest management, soil degradation, soil-borne diseases, and adaptation to climate change. However, due to limited knowledge, investigation of many factors is required to effectively implement soilless cultivation, among which are the substrate’s physical-hydraulic properties and suitability for grape production. In this context, we investigate the impact of the properties of organic (coir dust) and mineral (perlite, pumice) substrates and their blend (perlite:coir) on grapevine growth and grape physicochemical characteristics of Sugraone (Superior Seedless) and Prime cultivars. Perlite substrate was the best in qualitative and quantitative production characteristics, whereas pumice substrate proved unsuitable for soilless vine cultivation. Coir and perlite:coir substrates, due to their increased ability to retain moisture, improved plant nutrition and grape quality but delayed ripening. For effective soilless cultivation of grapevines and table grape production, substrates must have the ability to maintain sufficient but not excessive moisture, suitable for supporting physiological processes and plant nutrition, resulting in smooth growth and production.

Effects of Comparative Metabolism on Tomato Fruit Quality under Different Levels of Root Restriction

In a soilless culture (perlite substrate), root restriction cannot only reduce production costs but also improve fruit quality. Therefore, this study used different levels of root restriction [T1: 0.5 L, T2: 4 L, nonrestriction treatment (CK): 35 L] on tomatoes to explore their impact on quality. Results showed that total soluble solids (TSS), glucose, fructose, and sucrose contents were increased, whereas L-tryptophan, L-tyrosine, and titratable acidity were decreased under two restriction treatments. Meanwhile, root restriction also promoted the accumulation of phenylalanine and proline. For lycopene and flavonoid biosynthesis (prunin, naringin, naringenin), the restriction groups were significantly higher than those in the control group. Overall, T1 and T2 treatment had a better effect than CK treatment. This study provided an idea for improving substrate use efficiency and tomato quality.

The Use of Silicon Substrate Amendments to Decrease Micronutrient Concentrations at Varying Micronutrient Fertility Rates with Cannabis sativa ‘Auto CBG’

Many abiotic factors impact the yield and growth of Cannabis sativa (cannabis). Cannabis has been reported to be a bio-accumulator of heavy metals. For growers who are targeting floral production and other byproducts for human consumption, this is a concern. Silicon (Si) has been examined as a beneficial plant element to limit the uptake of heavy metals in a variety of crops. The objective of this study was to determine the impact of Si on heavy metal micronutrient uptake and plant growth for greenhouse-cultivated cannabis at varying Si substrate amendments. ‘Auto CBG’ plants were grown in a 70:30 peat:perlite substrate with one of three varying calcium silicate (CaSiO3) (Si) substrate amendment rates, Si0X, Si0.5X, or Si1X (of 0.0, 1.04, and 2.07 kg⋅m−3 CaSiO3), and one of three micronutrient fertility treatments, M1X [0.49 boron (B), 0.19 copper (Cu), 4.02 iron (Fe), 0.99 manganese (Mn), 0.01 molybdenum (Mo), and 0.20 zinc (Zn) mg⋅L−1], M2X, or M4X, using a modified Hoagland’s solution, creating a 3 × 3 factorial. Plants grown with a Si1X substrate amendment exhibited a significantly lower iron concentration in the foliage and root tissue when compared with those grown in a substrate without Si. After 6 weeks of growth, Si0X plants that received a M4X fertility rate exhibited greater foliar micronutrient concentrations of B, Mn, Zn, Fe, and Cu than plants that received a Si substrate amendment when provided a M4X fertility rate. Additionally, lower micronutrient concentrations in floral tissue were observed in plants that received a Si substrate amendment for M2X and M4X when compared with plants that did not. Silicon substrate amendments had no impact on the cannabinoid concentration or plant growth metrics after 12 weeks of growth. This research suggests that using a Si substrate amendment in a greenhouse production system can limit excessive uptake and accumulation of micronutrients in the foliage, roots, and floral material of cannabis without negative impacts on plant growth or cannabinoid concentrations.

Selection for Sustainable Preservation through In Vitro Propagation of Mature Pyrus spinosa Genotypes Rich in Total Phenolics and Antioxidants

Pyrus spinosa Forssk. (almond-leaved pear) is a wild-growing native tree of the hilly countryside of Greece, which has recently gained interest for its valuable endogenous substances. In the present work, the determination of the total phenol content (TPC) and antioxidant capacity (AC) was carried out during 2021 and 2022 in leaves from 32 genotypes of mature wild-growing trees at four different locations of Central Macedonia District, Greece: Agia Anastasia, Chalkidiki, Lagadas and Pieria. The measurements taken from the leaf samples of all genotypes revealed a strong positive linear correlation between TPC and AC (R2 = 0.772). Two genotypes from Agia Anastasia, coded as AA2 and AA3, were comparatively the richest in TPC (44.86 for AA2 and 46.32 mg GAE/g fresh weight for AA3) and AC (70.31 and 71.21 μg AAE/g fresh weight for the same genotypes). For these two genotypes of high TPC and AC, an efficient micropropagation protocol was developed to preserve and multiply this valuable germplasm. Newly emerged shoot tips were excised from winter shoots and, after disinfestation, they were established on a modified Murashige and Skoog (MS) nutrient medium with 5 μΜ of 6-Benzyloaminopurine (BAP). For shoot multiplication, explants from clean cultures were transferred to Pear Medium 1 with 5 μΜ of BAP. The effect of the nutrient medium was tested by using five different nutrient media (modified MS, Pear Medium 1, Pear Medium 2, DKW and WPM) supplemented with 5 μΜ of BAP. Pear Medium 1 was the most effective in shoot formation. Among the four different BAP concentrations (0, 5, 10 and 20 μΜ) used in Pear Medium 1, 5 μΜ of BAP resulted in the production of the significantly highest number of shoots (22.7 shoots per explant, 2.4 cm long). The exposure of cultures to 10 μmol·m−2·s−1 for one week under light irradiance followed by 35 μmol·m−2·s−1 for four weeks increased both the number and length of the shoots produced. A 20-s dip of the shoot bases into 49.0 μΜ of Indole-3-butyric acid (IBA) in EtOH equally affected rooting in a modified rooting MS (79%) and Pear Medium 1 (80%). The root system developed better in the modified rooting MS medium (mean number of roots of 2.7 with a length of 3.9 cm). The acclimatization of the plantlets was successfully carried out (high survival rates five weeks after their establishment) on a perlite substrate under controlled environmental conditions.

Investigation of the Effects of the Explant Type and Different Plant Growth Regulators on Micropropagation of Five Mediterranean Salvia spp. Native to Greece

Sages are medicinal and aromatic plants that constitute a large pool from which active compounds of great pharmaceutical potential can be derived, while at the same time, they also have ornamental value. The purpose of this study was to develop the micropropagation protocols of Salvia fruticosa, S. officinalis, S. ringens, S. tomentosa, and S. pomifera ssp. pomifera to facilitate their exploitation in the pharmaceutical and floriculture industries. In vitro cultures of S. ringens and S. pomifera ssp. pomifera was studied for the first time. Shoot tips and single node explants from in vitro seedlings were initially cultured on hormone free (Hf)-MS medium, followed by subcultures on MS medium supplemented with 6-benzyladenine (BA) for all species, as well as with zeatin (ZEA), kinetin (KIN), 6-(γ,γ-dimethylallyamino) purine (2iP), or meta-topolin (mT) for S. fruticosa and S. officinalis, at concentrations 0.0 to 3.2 mg L−1, in combination with 0.01 mg L−1 1-naphthaleneacetic acid (NAA). S. officinalis was the most efficient in shoot multiplication of all the studied species. The highest multiplication indices were found using 0.8 mg L−1 BA for S. fruticosa, 0.4 mg L−1 BA, or mT for S. officinalis, and lower than 0.8 mg L−1 BA for the other three species. Hyperhydricity was a problem at the multiplication stage, and was most pronounced in single node explants, increasing in proportion to cytokinin concentration. Microshoots rooted at high percentages (75–85%) on half-strength MS medium with 0.0 or 0.5 mg L−1 Indole-3-butyric acid (IBA), except for those of S. ringens, which rooted best at 1.0–2.0 mg L−1 IBA. Ex vitro acclimatization was highly successful (80–95%) on peat–perlite substrate (1:1 v/v). Thus, the present study resulted in efficient micropropagation protocols for five Mediterranean sage species native to Greece, which will facilitate breeding programs and the promotion of these species in the floriculture and pharmaceutical industries.

Crescimento de bulbos de Agave angustifolia em diferentes substratos, com doses de fertirrigação e inoculação com Azospirillum brasilense

ABSTRACT: There is little information about the production of agave plants in the nursery, so this research assessed the growth in the nursery of Agave angustifolia plants originating from inflorescence bulbils, subjected to different substrates, fertigation doses, and inoculation with Azospirillum brasilense. The bulbils were established for two months in a 50% peat-50% perlite substrate. One hundred and eighty plants were individually transferred to 3.8 dm3 pots for evaluation in an experiment with three factors: 1) type of irrigation: 1.1) water, or 1.2) fertigation with Steiner’s nutrient solution (NS), NS-50%, or 1.3) NS-100%; 2) inoculation with Azospirillum brasilense, 2.1) inoculated plants, 2.2) non-inoculated plants; 3) substrate, mixtures of bovine manure (BM) + sand (S) in different proportions, Mix1: 75% BM + 25% S; Mix2: 25% BM + 75% S; Mix3: 50% BM + 50% S. Morphological characteristics were quantified for one year. The largest plants were those that were in substrates with 50% BM, and were fertirrigated with NS-100% and inoculated with Azospirillum brasiliense. The smallest plants were those established a in a substrate with the lowest manure content, irrigated with only water and without inoculation, which was respectively 71.6 and 54.10 cm high, 21 and 15.6 leaves, 76.6 and 62.2 mm in stem diameter, 84.4 and 59.8 cm in rosette diameter.

Efficient micropropagation protocol of three cultivars of highbush blueberry (Vaccinium corymbosum L.)

Highbush blueberry (Vaccinium corymbosum L.) is increasingly farmed for its nutritional and health benefits, but high yield and fruit quality require proper planting material. Modified Murashige and Skoog (MW), Anderson’s Rhododendron (AN), and Woody Plant Medium (WPM) were compared for in vitro organogenesis and rooting of three highbush blueberries ‘Elizabeth’, ‘Meader’, and ‘Liberty’. All media contained 0.1 mg L-1 zeatin applied with a combination of IBA, IAA, and GA3. The results showed that MW medium is more suitable for in vitro multiplication of ‘Elizabeth’ and ‘Meader’, and WPM medium for ‘Liberty’. However, medium supplemented with a low concentration of IBA (≤ 0.4 mg L-1) and 0.1 mg L-1 zeatin increased the shoot regeneration rate of highbush blueberries multiplied in vitro. The rooting capability was studied by using WPM and AN medium with IBA and IAA with zeatin. The highest rooting rate (85%) and acclimatization (70%) were achieved in ‘Liberty’, and the lowest was in ‘Elizabeth’ (33.3% and 50%, respectively) and ‘Meader’ (33.3% and 43.8%, respectively). Rooted plantlets developed good quality roots and were transplanted into peat:perlite (4:1) substrates and acclimatized in a greenhouse under controlled conditions. We developed a complete micropropagation protocol for cvs. ‘Meader’, ‘Elizabeth’ and ‘Liberty’ blueberry. This protocol can be used for the production of certified vegetative material or different biotechnological purposes.

Effects of brown seaweed extract, silicon, and selenium on fruit quality and yield of tomato under different substrates.

Tomatoes (Lycopersicun esculentum L.) are an important group of vegetable crops that have high economical and nutritional value. The use of fertilizers and appropriate substrates is one of the important strategies that can assist in increasing the yield and quality of fruits. The present study aimed to investigate the effects of exogenous seaweed extract (Nizamuddinia zanardinii), silicon (Na2SiO3), and selenium (Na2SeO3) on quality attributes and fruit yield (FY) of tomato under palm peat + perlite and coco peat + perlite substrates. Seaweed extract significantly improved several of the fruit quality attributes such as total carbohydrate content, total soluble solids (TSS), and pH as well as the FY. The results showed that silicon (Si) (75 mg) was the best foliar spray treatment to enhance the fruit firmness (30.46 N), fruit volume (196.8 cm3), and FY (3320.5 g). The highest amount of plant yield (3429.33 g) was obtained by the interaction effects of silicon (75 mg L-1) under the effect of palm peat. The use of selenium (Se) led to improvements in flavor index (TSS/TA). Also, the application of palm peat + perlite substrate caused an increase in vitamin C (16.62 mg/100g FW), compared to other substrates (14.27 mg/100g FW). The present study suggested that foliar spray with seaweed extract and Si had beneficial effects on the quality and FY of tomatoes. Also, the palm peat substrate can be used as a good alternative to the coco peat substrate in the hydroponic system.

Improvement of Rooting Performance in Stem Cuttings of Savin Juniper (Juniperus sabina L.) as a Function of IBA Pretreatment, Substrate, and Season

Juniperus sabina is an interesting species for forest restoration and ornamental purposes. The seeds of this plant have several types of dormancies; therefore, seed propagation is difficult and time consuming. The production of cuttings can be an alternative way to produce plants more quickly. The main objective of this experiment was to determine the best propagation conditions (indole butyric acid dose, substrate, and season) for this species using stem cuttings. Rooting performance of the cuttings was evaluated based on the rooting percentage (%), root biomass, and specific root length (SRL). In addition, we examined the internal composition (auxin and peroxidase content) in treated stem cuttings. Cuttings were pretreated with five doses of indole butyric acid (IBA; 0 (control), 1000, 2000, 4000, and 8000 ppm) and were rooted in four substrates (perlite, perlite-cocopeat, pumice, and mixed substrate) during the four seasons (winter, spring, summer, and autumn). The best treatments, with more than 60% rooting, were applied in spring, and IBA at 1000 ppm in perlite–cocopeat substrate obtained 62% rooting. The highest rooting percentage correlated with the highest root biomass production and the lowest SRL. IBA pretreatment decreased the concentration of peroxidase in spring (coinciding with maximum rooting), representing an indicator of rooting performance. Based on these results, we recommend a new protocol for Juniperus sabina production: (i) prepare cuttings in spring, (ii) treat cutting bases with 1000 ppm IBA, and (iii) plant cuttings in a substrate of perlite–cocopeat (1:1).