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Liverwort coverage at 16 weeks after planting. Substrate consisted of 1/8 to 1/4-pine bark (PB) at 1 inch depth (1/8-1/4:S:1), 1/8 to 1/4-inch PB at 2 inches depth (1/8-1/4:S:2), 1/4 to 1/2-inch PB at 1 inch depth (1/4-1/2:S:1), 1/4 to 1/2-inch PB at 2-inch depth (1/4-1/2:S:2), 3/8 to 3/4-inch PB at 1 inch depth (3/8-3/4:S:1), 3/8 to 3/4-inch PB at 2 inches depth (3/8-3/4:S:2), #1/2-inch PB throughout (#1/2:TO); 1 inch 5 2.54 cm.
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Substrate stratification is a new research area in which multiple substrates, or the same substrate with differing physical properties, are layered within a container to accomplish a production goal, such as decreasing water use, nutrient leaching, or potentially reducing weed growth. Previous research using stratification with pine ( Pinus sp.) ba...
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... growth was highest in the industry-standard #1/2:TO substrate with an average coverage of 77% (Table 6) at 16 WAP. In all other treatments, liverwort coverage was negligible at less than 1% (Fig. 3). Similar results were reported in the previous study where the growth of liverwort was <1% in all stratified substrates (Kha- mare et al., 2022). Liverwort is known to be sensitive to cultural conditions, such as moisture levels and high fertility [i.e., nitrogen ( Newby et al., 2007)], and research has shown that mulch and alternative ...
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The objective of this study was to assess the growth of two woody ornamental plants when subjected to different levels of weed competition in four different container sizes, representing different stages of production. Ligustrum (Ligustrum lucidum W.T.Aiton) and Japanese holly (Ilex crenata Thunb.) liners were potted individually into 3.8 L, 11.4 L...
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... The following results were obtained for coarse (≥ 2 mm), medium (0.5-2 mm), and fine particles (≤ 0.5 mm in weight) (Khamare et al., 2022). Coarse particles: substrate 1 (17.3 %), substrate 2 (14.6 %), substrate 3 (14.8 ...
Fruit tree cultivation requires rootstocks that are resistant to both biotic and abiotic stresses. The container size and substrate used are essential components in their development. Despite this, there are few studies on the impact of substrates on plant development in citrus trees under nursery conditions. This study aimed to assess the effects of three different ratios of pine bark in the substrate of three developing citrus rootstocks in a protected environment (greenhouse). The study conducted at the Cazones Nursery in Cazones de Herrera, Veracruz, Mexico, hypothesized that an increase in bark proportion would lead to a rise in the physical and chemical characteristics of the substrate and the development of the three rootstocks. The study utilized a completely randomized design with a factorial arrangement (A × B). Factor A (rootstock) had three levels: Citrus aurantium L. (Sour Orange), C. volkameriana Pasq. (Volkamer Lemon), and C. sinensis L. × Poncirus trifoliata L. (Citrage C-35). Factor B (substrate) had four levels (0, 10, 20, and 30 % pine bark), resulting in 12 treatments with 20 repetitions each. The physical and chemical characteristics of the substrates were determined, and the plant height and stem diameter were measured. Pine bark positively affected the apparent and real densities, total porosity, electrical conductivity, and cation exchange capacity. The growth dynamics of the three rootstocks were greater during the second and third months after grafting. When grown in substrates with a total porosity of 46–54 %, Volkamer Lemon, Citrage C-35, and Sour Orange rootstocks reached a plant height of 124.1, 110.5, and 84.5 cm, respectively; the stem diameter reached 6.9 mm. Porosity and cation exchange capacity increased when pine bark was added to the substrates. By evaluating the substrates and managing them proportionally, it is possible to obtain plants suitable for grafting (with 5 to 6 mm of stem) within four months after transplanting. This results in less time spent in the nursery and reduced costs.
... Accordingly, P that is released from the fertilizer and leaches past the root zone may be adsorbed to the FSB before draining from the container. Growing containerized nursery and greenhouse crops in strategic layers of substrate, sometimes referred to as substrate stratification, has recently been proposed to decrease fertilizer requirements [30], reduce weed growth and weed seed germination [31,32], mitigate crop water stress during drought [33], and reduce peat use [34]. However, stratifying a substrate to include a P-sorbing base layer has not yet been explored. ...
Phosphorus (P) fertilizers applied to container-grown nursery crops readily leach through pine bark-based substrates and can subsequently runoff and contribute to surface water contamination. The objectives of this research were to determine the effect of adding a layer of FeSO4·7H2O-amended pine bark (FSB) to the bottoms of nursery containers on P leaching characteristics. Phosphorus and iron (Fe) leaching in response to FSB layer height (4 or 7.5 cm), FeSO4·7H2O rate (0.3, 0.6, or 1.2 kg·m⁻³ Fe), and form (i.e., granular versus liquid) used to formulate the FSB layer, and the inclusion of dolomite in the FSB layer were also investigated. Greenhouse studies lasting 15 and 19 weeks were conducted, in which 2.5 L nursery containers containing the FSB layer treatments below non-amended pine bark substrate were fertilized with 199 or 117 mg P from a soluble or controlled-release fertilizer, respectively. Leachate resulting from daily irrigation was collected and analyzed for P and Fe weekly. All FSB treatments leached less P than the control (non-amended pine bark only), with P reductions ranging from 22% (4 cm FSB with 0.3 kg·m⁻³ Fe) to 73% (7.5 cm FSB with 1.2 kg·m⁻³ Fe). Phosphorus leaching decreased linearly with an increase in Fe rate or layer height. The amount of Fe that leached from containers with FSB was <5% of that applied, regardless of the Fe rate. Granular- and liquid-applied FeSO4·7H2O with or without dolomite were equally effective at reducing P leaching. Adding 0.6 kg·m⁻³ Fe to the bottom 500 cm³ of pine bark increased P adsorption by 0.053 mg·cm⁻³ P, which equates to 17.9 mg P adsorbed per gram of FeSO4·7H2O added. Results from this research suggest that including an FSB layer in the bottom of nursery containers is an effective strategy for reducing P runoff from container-based nursery production sites.
... Stratified substrates have presented numerous opportunities to improve production sustainability through weed suppression and decreased herbicide use/cost (Khamare et al., 2022), explore fertilizer placement strategies (Ammons et al., 2022), reduce fertilizer inputs by 20% , and lessen irrigation use by 25% compared to traditional nursery application rates (Criscione, Fields, Owen, Fultz, et al., 2022). Additionally, plant establishment and growth with regard to root biomass and shoot quality (Criscione, Fields, Owen, Fultz, et al., 2022) are enhanced in stratified-grown crops when compared to crops grown in traditional substrate systems. ...
The specialty crop industry requires copious amounts of water to meet production needs; however, current substrates are highly porous to mitigate risks and are subsequently inefficient with regard to water use. Therefore, more sustainable soilless substrates are needed to ensure the future success/profitability of the horticultural industry, especially as finite fresh water sources become limiting. Substrate stratification (i.e., vertically layering unique substrates atop one another) provides opportunities to augment an existing system by maintaining substrate porosity, while strategically redistributing the air‐ and water‐filled pores, retaining more water when applied, and controlling vertical water distribution. The aim of this research was to further understand the complex stratified systems of hydraulics. Herein, the hydraulic properties of individual substrate components were measured and modeled using HYDRUS 1 d. Furthermore, matric tensions and volumetric water content (VWC) were measured continuously under two different irrigation schedules (single [1×] and cyclic applications [3×]) for 15 days with a fully established Dianthus barbatus ‘Amazon Neon Purple’ crop. The results showed that screened bark particles have more pore homogeneity assessed by steep declines in VWC with small changes in water potential. Moreover, HYDRUS 1 d modeling demonstrated that stratified substrates have more uniform hydraulic gradients (difference in moisture content from the top to the bottom of the substrate profile; 21%) present in the container profile when compared to non‐stratified systems (45%). Non‐stratified upper layers experienced greater diurnal tension fluctuations under single irrigation than in cyclic applications. Stratifying substrates resulted in a significant reduction in these fluctuations in the top layer when compared to non‐stratified systems. Additionally, when both substrate (stratifying) and irrigation (cyclic) management strategies are implemented, tension fluctuations can be even further reduced, and hydraulic gradients become more uniform due to improved moisture infiltration and distribution.
... Others have applied substrate stratification concepts to further impact fertility, augmenting controlled-release-fertilizer placement to increase longevity and decrease mineral leaching by strategically placing mineral nutrients only in the upper profile (Ammons et al., 2022) suggesting improved fertilizer management is attainable, with supporting literature (Hoskins et al., 2014). Khamare et al. (2022) inverted the stratified system by placing screened coarse bark particles in the upper layer which reduced weed germination and subsequent herbicide application costs. As more stratified substrate research is conducted, more resource efficient opportunities are likely to be presented. ...
Containerized crop production is an intensely managed system comprise of highly porous substrates that rely upon natural resources (i.e., peat, bark, water, and mineral nutrients) to quickly provide salable crops throughout the year. The costs of these finite resources have been rising partly in response to soilless production practices expanding into new agricultural sectors and supply chain matters. To alleviate rising costs and supply limitations, researchers must identify new and innovative crop-production strategies. Substrate stratification is an emerging substrate management technique that involves layering unique substrates within a container for more precise control of container-substrate air or water gradient. Results have demonstrated improved resource efficiency, allowing strategic fertilizer placement to reduce overall fertilizer requirements and improved productivity when produced under deficit water management. More recent evidence has shown improved root productivity for crops grown in stratified substrates. Most recently, peat reduction through utilization of stratified systems, peat atop bark, has been successfully employed. Thus, stratified substrates are gaining interest in both nursery and greenhouse production. As we continue to uncover the benefits of alternative media management strategies like stratified substrates, more refined research is necessary to quantify the advantages to growers, researchers, and the global public. This paper will explore the present and future of stratified substrate research, focusing on the beginning theories through current discoveries. We will discuss existing technologies and upcoming experimentation plans to advance stratified substrate science and further explore associated benefits with the goal of expanding innovative agriculture research to yield more cost-effective and environmentally friendly production strategies that are achievable through soilless substrate science.
... Substrate stratification, a new substrate management approach, has been shown to be a tool for weed management [10,11]. Substrate stratification involves creating layers of diverse substrates or textures of the same substrate within a container [12]. ...
... Substrate stratification involves creating layers of diverse substrates or textures of the same substrate within a container [12]. Substrate stratification was initially designed to improve water and fertilizer efficiency [13][14][15], and then in other work, the original principle was modified to evaluate its use to control weeds [10,11]. The method of substrate stratification for weed management involves using larger, coarse, and easily draining particles as the top strata without any fertilizer and a substrate that is highly capable of retaining moisture, finely textured, with fertilizer incorporated as the bottom strata [10]. ...
... As a result, the top stratum of the substrate lacks nutrients or moisture for weed seeds to establish. In previous studies, substrate stratification has been shown to decrease the growth of spotted spurge (Euphorbia maculata) by 14 to 55%, bittercress (Cardamine flexuosa) by 80 to 97%, and liverwort (Marchantia polymorpha) coverage by 95 to 99% [11]. ...
The objective of this study was to determine how topdressing or incorporating fertilizer with stratified or mulched substrates could affect the growth of Hibiscus rosa-sinensis ‘Snow Queen’, a popular ornamental plant, and the growth of liverwort (Marchantia polymorpha) and bittercress (Cardamine flexuosa), two common nursery weed species. Five different substrate treatments were evaluated, which included three stratified substrates composed of pine bark screened to a small (0.63–1.27 cm), medium (≤1.90 cm), and large (0.96–1.90 cm) particle size and two industry-standard substrates that were either mulched with rice hulls or remained unmulched. All treatments were then fertilized via either topdressing or incorporating a controlled-release fertilizer (CRF). Bittercress control was highest in mulched containers, followed by those stratified using the medium pine bark, and its growth increased overall in topdressed vs. incorporated containers regardless of substrate or mulch treatment. All the stratification treatments resulted in a decrease in liverwort coverage compared to the industry standard treatment, but topdressing generally increased liverwort coverage compared with incorporating fertilizer. In conclusion, both topdressing and incorporation appear to be compatible with fertilizer placement methods with substrate stratification from a crop production standpoint; however, weed growth may increase if fertilizer is topdressed.
... Evidence has also shown improved containerized crop rooting in stratified systems when compared with conventional growing practices (Fields et al. 2022). Moreover, others have used stratified substrate concepts to stratify controlled-release-fertilizer placement (Ammons et al. 2022) and to reduce weed germination and associated herbicide application costs in container systems (Khamare et al. 2022). As substrate stratification research continues, additional benefits for this practice in greenhouse crop production systems will arise. ...
Peat use in horticulture continues to be scrutinized as consumers are becoming increasingly aware of the environmental sustainability concerns associated with peat. Thus, the horticultural industry is driven to search for peat alternatives. Substrate stratification (i.e., vertical layering of unique media atop another in a singular container) has been studied in nursery substrates and has demonstrated improved resource efficiency with regard to water and fertilizer inputs. However, minimal research has evaluated using the concept of stratified substrates as an attempt to reduce peat inputs in greenhouse production. Hence, the objective of this study was to identify if stratifying costly floriculture media atop of low-cost pine bark can reduce peat use, reliance, and cost within the floriculture industry. A floriculture crop, Petunia hybrid ‘Supertunia Honey’, was grown in two distinct substrate treatments: 1) nonstratified (commercial peat-based floriculture substrate) and 2) stratified peat-based substrate layered atop aged pine bark (1:1 by volume) under two different irrigation schedules. Crop growth was evaluated, including growth indices, shoot physiological responses, and root growth measurements. Substrate hydraulic properties such as matric potential and volumetric water content were monitored over time. The results demonstrated that a petunia crop can be produced in stratified substrate systems and yield similarly sized and quality crops as traditionally grown plants. Furthermore, the stratified substrate-produced crop had improved root productivity, yet less bloom, when compared with nonstratified-grown crops.
Hundreds of new woody ornamental plant cultivars are introduced into the nursery industry each year which have many desirable aesthetic traits. However, in recent years growers have reported a higher level of herbicide sensitivity with certain cultivars compared with older cultivars that have been in the trade for multiple years. The objective of this research was to determine the tolerance of 12 different cultivars of five ornamental species including four cultivars of Loropetalum chinense [‘Ruby’, ‘Shang-hi’ PP18331 (Purple Diamond®), ‘Irodori’ USPP 27713 (Jazz Hands®), and ‘PIILC-I’ (Crimson Fire™), and two cultivars of Gardenia jasminoides (‘Frostproof’ and ‘Buttons’), Lagerstroemia indica [‘JM7’ PP34092 (Thunderstruck™ Ruby) and ‘Tuscarora’], Rhododendron [‘Conlet’ PP12111 (Autumn Carnival Encore®) and ‘Fashion’], and Ligustrum sinense Sunshine (‘Sunshine’ PP20379 and ‘Variegatum’) to spray-applied applications of dimethenamid-P or isoxaben + prodiamine and granular applications of dimethenamid-P + pendimethalin and indaziflam. While little to no injury was observed in gardenia or crape myrtles, significant injury and differences among cultivars of the same species were observed in azalea, loropetalum, and ligustrum. Results indicate that all new cultivars should be evaluated for herbicide tolerance by growers prior to wide scale application as significant differences in both growth and injury ratings were observed between different cultivars of the same species.
Species used in this study: Ruby Loropetalum (Loropetalum chinense (R.Br.) Oliv. ‘Ruby’); Purple Diamond® loropetalum (Loropetalum chinense ‘Shang-hi’ PP18331); Jazz Hands loropetalum (Loropetalum chinense ‘Irodori’ USPP 27713); Crimson Fire™ loropetalum (Loropetalum chinense var. rubrum ‘PIILC-I’); Frostproof gardenia (Gardenia jasminoides J.Ellis ‘Frostproof’); Buttons gardenia (Gardenia jasminoides ‘Buttons’); Thunderstruck™ Ruby crape myrtle (Lagerstroemia × ‘JM7’ PP34092); Tuscarora crape myrtle (Lagerstroemia indica L. ‘Tuscarora’); Autumn Carnival Encore® azalea (Rhododendron ‘Conlet’ PP12111); Fashion azalea (Rhododendron × ‘Fashion’); Sunshine ligustrum (Ligustrum sinense Lour. ‘Sunshine’ PP20379); Variegated ligustrum (Ligustrum sinense ‘Variegatum’).
Chemicals used in this study: dimethenamid-P (Tower®), (S)-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-acetamide; dimethenamid-P+ pendimethalin (FreeHand®) (S)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethyl-thien-3-yl)-acetamide + N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenam; indaziflam (Marengo®G) N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-[(1RS)-1 fluoroethyl]-1,3,5-triazine-2,4-diamine; prodiamine + isoxaben (Gemini® SC) 2,6-Dinitro-N1,N1-dipropyl-4-(trifluoromethyl)benzene-1,3-diamine + 2,6-Dimethoxy-N-[3-(3-methylpentan-3-yl)-1,2-oxazol-5-yl]benzamide.
Weed management in container plant production is a serious problem and remains one of the most expensive and time-consuming aspects of the industry. Weeds cause severe reductions in crop growth due to the limited growing environment characteristic of container plant production. The container nursery industry relies heavily on a limited number of preemergence herbicide options. The use of herbicides as the primary means to manage weeds has resulted in some negative consequences such as high chemical costs, leaching, runoff, and concerns with recycling irrigation water. Additionally, nursery growers are shifting their focus toward different nonchemical weed management strategies because many ornamental plants are very sensitive to preemergence herbicides. One such method is using organic mulch to control weeds in container plant production. Mulching is the foundation of a nonchemical weed management protocol and acts as the first line of defense against weeds. Organic mulches used in container plant production include rice hulls, pine bark, wood chips, wood shavings, coconut coir, nut (peanut, pecan) shells, oyster shells, cacao bean hulls, pelletized newspaper, recycled newspaper, pine straw, and other materials; material selection often depends on the availability of the product. The objective of this manuscript is to provide a comprehensive review of existing research on the utilization of various mulch materials as a weed management tool in container plant production. Additionally, it aims to highlight any critical knowledge gaps and provide suggestions for possible future research.
