Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae

Container-grown nursery crops are commonly exposed to root zone stress due to inadequate moisture and supraoptimal root zone temperature (RZT). Compost substrates can improve water and nutrient retention but plant responses can vary due to physical and chemical properties. Dark color containers absorb solar radiation through the container side wall leading to excessive heat buildup in the substrate, yet white containers can reduce RZT. Compost substrates and container color were examined for effects on RZT and growth of “Green Giant” arborvitae (Thuja standishii × plicata “Green Giant”). “Green Giant” arborvitae were transplanted into white or black containers (11.3 L) filled with a pine bark substrate (PB) or PB mixed with compost (C) at two different proportions [PB:C (9:1) and PB:C (7:3)]. White containers reduced maximum RZT by up to 7 °C and RZT remained above 38 °C for only 3% of the time compared to 21% of the time in black containers. Shoot growth increased over 50% in white containers compared to black containers. Compost increased substrate volumetric water content (VWC), increased shoot growth by up to 24%, and reduced total irrigation volume by up to 40%. Utilizing white containers for minimizing RZT and compost-amended substrates to maintain adequate VWC can improve root and shoot growth and overall crop quality while reducing nursery production inputs

Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae

Root zone temperature (RZT) in nursery containers commonly exceeds ambient temperature during the growing season, negatively impacting crop growth and quality. Black nursery containers absorb radiant heat resulting in excessive RZT, yet other types of containers and different substrates can moderate RZT. We conducted studies in Tennessee and Alabama to evaluate the effects of container type and substrate on RZT and growth of ‘Green Giant’ arborvitae (Thuja standishii × plicata ‘Green Giant’). Trade gallon arborvitae were transplanted into black, white, or air pruning containers filled with pine bark (PB) or 4 PB: 1 peatmoss (v:v) (PB:PM). Plants grown in PB:PM were larger and had greater shoot and root biomass than plants grown in PB, likely due to increased volumetric water content. Plant growth response to container type varied by location, but white containers with PB:PM produced larger plants and greater biomass compared with the other container types. Root zone temperature was greatest in black containers and remained above 38 °C and 46 °C for 15% and 17% longer than white and air pruning containers, respectively. Utilizing light color containers in combination with substrates containing peatmoss can reduce RZT and increase substrate moisture content thus improving crop growth and quality

Stem Cutting Propagation in Whole Pine Tree Substrates

Wood-based substrates have been extensively evaluated for greenhouse and nursery crop production, yet these substrates have not been evaluated for propagation. The objective of this study was to evaluate processed whole loblolly pine trees (WPT) (Pinus taeda) as a rooting substrate for stem cutting propagation of a range of ornamental crops. Substrates included processed WPT, pine (Pinus sp.) bark (PB), and each mixed with equal parts (by volume) peatmoss (PM) (WPT:PM and PB:PM, respectively). Substrate physical (air space, container capacity, total porosity, bulk density, and particle size distribution) and chemical [pH and electrical conductivity (EC)] properties were determined for all substrates. Rooting percentage, total root length, total root volume, and total shoot length were evaluated for four species in 2008 and five species in 2009. Substrate air space was similar between PB and WPT in the 2008 experiment, and likewise between PB:PM and WPT:PM. In the 2009 experiment, PB and WPT had similar substrate air space. The addition of PM to PB and WPT resulted in reduced air space and increased container capacity in both experiments. The proportion of fine particles doubled for PB:PM and WPT:PM compared with PB and WPT, respectively. Substrate pH for all substrates ranged from 6.0 to 6.9 at 7 days after sticking (DAS) cuttings and 6.9 to 7.1 at 79 DAS. Substrate EC was below the acceptable range for all substrates except at 7 DAS. Rooting percentage was similar among substrates within each species in both experiments. The addition of PM resulted in significantly greater total root length for PB:PM and WPT:PM compared with PB and WPT, respectively, for five of the eight species. Shoot growth was most vigorous for PB:PM compared with the other substrates for all species. The study demonstrated a range of plant species can be propagated from stem cuttings in whole pine tree substrates alone or combined with PM

Rooting and vegetative growth of hardwood cuttings of 12 pomegranate (\u3ci\u3ePunica granatum\u3c/i\u3e L.) cultivars

Commercial pomegranate production area has increased substantially in the western hemisphere due to increased consumer interest in the fruit. Low nursery inventory has caused many growers to propagate vegetatively their own trees and the availability of only a few cultivars is believed to have played a role in a lack of diversity in the developing market. ‘Wonderful,’ the industry standard for pomegranate in several countries, has been propagated in the United States for over 100 years, yet there is limited scientific information regarding how to most effectively propagate ‘Wonderful’ and other important cultivars. This research included two experiments. Experiment 1 evaluated rooting percentages and vegetative growth attributes of hardwood cuttings of twelve cultivars (‘Ambrosia,’ ‘Desertnyi,’ ‘Eversweet,’ ‘Golden Globe,’ ‘Green Globe,’ ‘Haku Botan,’ ‘Ki Zakuro,’ ‘Loffani,’ ‘Nochi Shibori,’ ‘Parfianka,’ ‘Phoenicia,’ and ‘Wonderful’) utilizing a basal dip in a gel formulation of 3 g·L−1 indole-3-butyric acid (IBA). Experiment 2 evaluated auxin treatments which consisted of basal dip in water only (control) or a gel formulation of IBA (1.5 g L−1 or 3 g L−1) for hardwood cuttings of ‘Wonderful’ and two cultivars that rooted poorly in Experiment 1: ‘Ambrosia’ and ‘Green Globe.’ Measured response attributes included rooting success percentages, dry root mass, leaf area, plant height, number of shoots, apical shoot growth, total shoot length, branching, stem diameter, and relative chlorophyll content (SPAD value). ‘Wonderful’ and nine other cultivars rooted over 84% of the time using cuttings treated with 3 g L−1 IBA. Differences in plant height and branching could be detected early in production. The effect of IBA concentration on rooting percentage and growth attributes varied among cultivars. Cuttings of ‘Ambrosia’ rooted best with 3 g L−1 IBA versus 0 and 1.5 g L−1 IBA, whereas rooting of cuttings of ‘Green Globe’ was similar among IBA rates. Plants of ‘Wonderful’ had significantly greater leaf area compared to those of ‘Ambrosia’ and ‘Green Globe.’ Stem diameter had no effect on rooting on any cultivar in either experiment. There were significant differences among cultivars in terms of chlorophyll content, with ‘Haku Botan’ and ‘Loffani’ having greener leaves than ‘Eversweet,’ ‘Ambrosia,’ and ‘Desertnyi.

Alginate Encapsulation of Begonia Microshoots for Short-Term Storage and Distribution

Synthetic seeds were formed from shoot tips of two in vitro grown Begonia cultivars using 3% sodium alginate in Murashige and Skoog medium (MS) salt solution as the gel matrix and 100 mM calcium chloride for complexation. Synthetic seed formation was achieved by releasing the sodium alginate/explant combination into 100 mM calcium chloride (CaCl 2 ⋅H 2 O) solution for 30 or 45 min. Both control and encapsulated shoots were transferred into sterile Petri dishes and stored at 4 ∘ C or 22 ∘ C for 0, 2, 4, 6, or 8 weeks. Conversion of synthetic seeds into plantlets for both storage environments was assessed in MS medium or peat-based substrate. No significant difference was found between the 30 and 45 min CaCl 2 ⋅H 2 O treatments or the two cultivars. Encapsulation of explants improved survival rate over time irrespective of the medium type or storage environment. Survival rates of 88, 53, 28, and 11% for encapsulated microshoots versus 73, 13, 0, and 0% for control explants were achieved in microshoots stored for 2, 4, 6, and 8 weeks, respectively. The best results were obtained when synthetic seeds were stored at 4 ∘ C and germinated on MS medium. Regenerated plantlets were successfully established in potting soil

Investigating the effects of planting date and Aphis gossypii management on reducing the final incidence of cotton leafroll dwarf virus

This is the first study to research management strategies for cotton leafroll dwarf virus (CLRDV) in the southeastern U.S. The efficacy of aphid vector management to reduce final CLRDV incidence was investigated concurrent with efforts to monitor aphid population dynamics and timing of CLRDV spread. Adjusting the planting date and insecticide applications did not reduce the final incidence of CLRDV, which was confirmed in 60–100% of plants per plot using RT-PCR. Aphid population density was reduced, but not eliminated with foliar insecticide applications. Aphis gossypii was the only species observed on cotton and was the dominant species collected in pan traps. Three distinct periods of virus spread were detected with sentinel plants including early, mid-and late-season. Most virus spread occurred during large aphid dispersal events

On the Two Species Asymmetric Exclusion Process with Semi-Permeable Boundaries

We investigate the structure of the nonequilibrium stationary state (NESS) of a system of first and second class particles, as well as vacancies (holes), on L sites of a one-dimensional lattice in contact with first class particle reservoirs at the boundary sites; these particles can enter at site 1, when it is vacant, with rate alpha, and exit from site L with rate beta. Second class particles can neither enter nor leave the system, so the boundaries are semi-permeable. The internal dynamics are described by the usual totally asymmetric exclusion process (TASEP) with second class particles. An exact solution of the NESS was found by Arita. Here we describe two consequences of the fact that the flux of second class particles is zero. First, there exist (pinned and unpinned) fat shocks which determine the general structure of the phase diagram and of the local measures; the latter describe the microscopic structure of the system at different macroscopic points (in the limit L going to infinity in terms of superpositions of extremal measures of the infinite system. Second, the distribution of second class particles is given by an equilibrium ensemble in fixed volume, or equivalently but more simply by a pressure ensemble, in which the pair potential between neighboring particles grows logarithmically with distance. We also point out an unexpected feature in the microscopic structure of the NESS for finite L: if there are n second class particles in the system then the distribution of first class particles (respectively holes) on the first (respectively last) n sites is exchangeable.Comment: 28 pages, 4 figures. Changed title and introduction for clarity, added reference

Transient exposure to low levels of insecticide affects metabolic networks of honeybee larvae

The survival of a species depends on its capacity to adjust to changing environmental conditions, and new stressors. Such new, anthropogenic stressors include the neonicotinoid class of crop-protecting agents, which have been implicated in the population declines of pollinating insects, including honeybees (Apis mellifera). The low-dose effects of these compounds on larval development and physiological responses have remained largely unknown. Over a period of 15 days, we provided syrup tainted with low levels (2 µg/L−1) of the neonicotinoid insecticide imidacloprid to beehives located in the field. We measured transcript levels by RNA sequencing and established lipid profiles using liquid chromatography coupled with mass spectrometry from worker-bee larvae of imidacloprid-exposed (IE) and unexposed, control (C) hives. Within a catalogue of 300 differentially expressed transcripts in larvae from IE hives, we detect significant enrichment of genes functioning in lipid-carbohydrate-mitochondrial metabolic networks. Myc-involved transcriptional response to exposure of this neonicotinoid is indicated by overrepresentation of E-box elements in the promoter regions of genes with altered expression. RNA levels for a cluster of genes encoding detoxifying P450 enzymes are elevated, with coordinated downregulation of genes in glycolytic and sugar-metabolising pathways. Expression of the environmentally responsive Hsp90 gene is also reduced, suggesting diminished buffering and stability of the developmental program. The multifaceted, physiological response described here may be of importance to our general understanding of pollinator health. Muscles, for instance, work at high glycolytic rates and flight performance could be impacted should low levels of this evolutionarily novel stressor likewise induce downregulation of energy metabolising genes in adult pollinators

Rooting and vegetative growth of hardwood cuttings of 12 pomegranate (\u3ci\u3ePunica granatum\u3c/i\u3e L.) cultivars

Commercial pomegranate production area has increased substantially in the western hemisphere due to increased consumer interest in the fruit. Low nursery inventory has caused many growers to propagate vegetatively their own trees and the availability of only a few cultivars is believed to have played a role in a lack of diversity in the developing market. ‘Wonderful,’ the industry standard for pomegranate in several countries, has been propagated in the United States for over 100 years, yet there is limited scientific information regarding how to most effectively propagate ‘Wonderful’ and other important cultivars. This research included two experiments. Experiment 1 evaluated rooting percentages and vegetative growth attributes of hardwood cuttings of twelve cultivars (‘Ambrosia,’ ‘Desertnyi,’ ‘Eversweet,’ ‘Golden Globe,’ ‘Green Globe,’ ‘Haku Botan,’ ‘Ki Zakuro,’ ‘Loffani,’ ‘Nochi Shibori,’ ‘Parfianka,’ ‘Phoenicia,’ and ‘Wonderful’) utilizing a basal dip in a gel formulation of 3 g·L−1 indole-3-butyric acid (IBA). Experiment 2 evaluated auxin treatments which consisted of basal dip in water only (control) or a gel formulation of IBA (1.5 g L−1 or 3 g L−1) for hardwood cuttings of ‘Wonderful’ and two cultivars that rooted poorly in Experiment 1: ‘Ambrosia’ and ‘Green Globe.’ Measured response attributes included rooting success percentages, dry root mass, leaf area, plant height, number of shoots, apical shoot growth, total shoot length, branching, stem diameter, and relative chlorophyll content (SPAD value). ‘Wonderful’ and nine other cultivars rooted over 84% of the time using cuttings treated with 3 g L−1 IBA. Differences in plant height and branching could be detected early in production. The effect of IBA concentration on rooting percentage and growth attributes varied among cultivars. Cuttings of ‘Ambrosia’ rooted best with 3 g L−1 IBA versus 0 and 1.5 g L−1 IBA, whereas rooting of cuttings of ‘Green Globe’ was similar among IBA rates. Plants of ‘Wonderful’ had significantly greater leaf area compared to those of ‘Ambrosia’ and ‘Green Globe.’ Stem diameter had no effect on rooting on any cultivar in either experiment. There were significant differences among cultivars in terms of chlorophyll content, with ‘Haku Botan’ and ‘Loffani’ having greener leaves than ‘Eversweet,’ ‘Ambrosia,’ and ‘Desertnyi.

Stem Cutting Propagation in Whole Pine Tree Substrates

Wood-based substrates have been extensively evaluated for greenhouse and nursery crop production, yet these substrates have not been evaluated for propagation. The objective of this study was to evaluate processed whole loblolly pine trees (WPT) (Pinus taeda) as a rooting substrate for stem cutting propagation of a range of ornamental crops. Substrates included processed WPT, pine (Pinus sp.) bark (PB), and each mixed with equal parts (by volume) peatmoss (PM) (WPT:PM and PB:PM, respectively). Substrate physical (air space, container capacity, total porosity, bulk density, and particle size distribution) and chemical [pH and electrical conductivity (EC)] properties were determined for all substrates. Rooting percentage, total root length, total root volume, and total shoot length were evaluated for four species in 2008 and five species in 2009. Substrate air space was similar between PB and WPT in the 2008 experiment, and likewise between PB:PM and WPT:PM. In the 2009 experiment, PB and WPT had similar substrate air space. The addition of PM to PB and WPT resulted in reduced air space and increased container capacity in both experiments. The proportion of fine particles doubled for PB:PM and WPT:PM compared with PB and WPT, respectively. Substrate pH for all substrates ranged from 6.0 to 6.9 at 7 days after sticking (DAS) cuttings and 6.9 to 7.1 at 79 DAS. Substrate EC was below the acceptable range for all substrates except at 7 DAS. Rooting percentage was similar among substrates within each species in both experiments. The addition of PM resulted in significantly greater total root length for PB:PM and WPT:PM compared with PB and WPT, respectively, for five of the eight species. Shoot growth was most vigorous for PB:PM compared with the other substrates for all species. The study demonstrated a range of plant species can be propagated from stem cuttings in whole pine tree substrates alone or combined with PM