Abstract.A promotive effect of ethylene on the formation of adventitious roots by mung bean cuttings was demonstrated using a recirculating solution culture system to apply dissolved ethylene. The number of roots increased in proportion to the length of exposure to the gas. Mean root numbers per cutting for a 4-day exposure to ethylene and an air control were 45 and 19, respectively. The tissue was most sensitive to a 24-h ethylene '~pulse" 2-3 days after taking cuttings. Rooting was maximal at a concentration of 13 t~1 1-1 ethylene. The ethylene treatment inhibited the growth of roots and terminal buds. Application of Ag § , as silver thiosulfate, reversed the effect of ethylene on the two growth responses but had no effect on root numbers. Norbornadiene, another inhibitor of ethylene action, reversed all three ethylene responses.Numerous workers have used the ethylene-releasing compound (2-chloroethyl) phosphonic acid (ethephon) to examine the effect of ethylene on the rooting of cuttings. Although the results of these studies have been quite variable

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Water was withheld from 2-year-old seedlings or rooted cuttings of four birch genotypes (Betula alleghaniensis Britton, B. davurica Pall., B. nigra L. ‘Cully’, and B. papyrifera Marsh.) until the combined weight of the container and plant decreased below 40% of its original value to induce plant predawn water potential between −1.5 MPa and −2.1 MPa, after which plants were supplied with a requisite amount of water to reach 40% of its original value for 5 weeks under controlled conditions to investigate changes in gas exchange, osmotic solutes, leaf abscission, and growth compared with well-watered (WW) plants. Observations indicated that three of the four genotypes (except B. papyrifera) expressed three stages of photosynthetic response during water deficit: 1) a stress stage, 2) an acclimation stage, and 3) an adapted (or tolerance) stage. The stages were characterized by decreasing, increasing, and stabilized Pnws/ww (net photosynthesis presented as a ratio of water-deficit stressed (WS) plants to WW plants), respectively. A strong relationship between Pn and g S observed in the WS plants of the four genotypes, suggested inhibition of Pn by stomatal closure. After exposure to water deficit for 5 weeks, Pnws/ww recovered to 70% of the initial value for B. alleghaniensis and B. nigra ‘Cully’ and 98% for B. davurica and B. papyrifera. WS plants had higher foliar concentrations of chlorophyll a and b (nmol/g) and potassium (%) than the WW plants. Increased levels of polyols (mg/g) were detected only in the WS plants of B. allegahaniensis. Increased levels of carbohydrates or organic acid under water deficit were not detected. A significant increase in leaf abscission in the WS plants of B. papyrifera compared with the other genotypes could be a morphological adaptation to water deficit conditions and facilitate recovery of Pnws/ww during the acclimation stage.

The decline in the availability of pine (Pinus taeda L.) bark (PB) supplies and increasing prices have caused concerns in the nursery industry. Research was conducted to evaluate the effect of parboiled rice (Oryza sativa L.) hulls (PBH) as a substrate amendment to PB-based container substrates on the growth of Spiraea ×bumalda L. ‘Anthony Waterer’ and to examine the changes in physical properties of the substrates during long-term production cycles under outdoor nursery conditions. Six substrates were formulated by blending PB with 0%, 20%, 40%, 60%, 80%, or 100% PBH (by volume). Substrate composition affected plant growth components evaluated, generally decreasing growth as the amount of PBH increased. However, amending PB with up to 40% PBH did not result in a significant decrease in plant growth or increase the volume or frequency of irrigation for container-grown spirea. Physical properties of substrates amended with PBH improved over time. Based on these results, PB-based substrates amended with up to 40% PBH retained physical properties that were generally within current guidelines for nursery container substrates after one (25 weeks) and two (70 weeks) growing seasons.

Collection of plant inventory (i.e., count, grade, plant size, yield) data is time-consuming, costly, and can be inaccurate. In response to increasing labor costs and shortages, there is an increased need for the adoption of more automated technologies by the nursery industry. Growers, small and large, are beginning to adopt technologies (e.g., plant spacing robots) that automate or augment certain operations, but greater strides must be taken to integrate next-generation technologies into these challenging unstructured agricultural environments. The main objective of this work is to demonstrate merging specific ground and aerial-based technologies (Radio Frequency Identification (RFID), and small Unmanned Aircraft System (sUAS)) into a holistic systems approach to address the specific need of moving toward automated on-demand plant inventory. This preliminary work focuses on evaluating different RFID tags with respect to their distance and orientation to the RFID reader. Fourteen different RFID tags, five distances (1.5 m, 3.0 m, 4.5 m, 6.0 m, and 7.6 m), and four tag orientations (the front of the tag (UP), back of the tag (DN), tag at sideways left (SL), and tag at sideways right (SR)) were assessed. Results showed that the tag upward orientation resulted in the highest scanning total for both the laboratory and field experiments. Two orientations (UP and SR) had significant effect on the scan total of tags. The distance between the reader and the tags at 1.5 m and 6.0 m did not significantly affect the scanning efficiency of the RFID system in horizontally fixed (p-value > 0.05) position regardless of tags. Different tag designs also produced different scan totals. Overall, since most of the tags were scanned at least once (except for Tag 6F), it is a very promising technology for use in nursery inventory data acquisition. This work will create a unique inventory system for agriculture where locations of plants or animals will not present a barrier as the system can easily be mounted on a drone. Although these experiments are focused on inventory in plant nurseries, results for this work has potential for inventory management in other agricultural sectors.

Background: With their unique history of exposure to extensive nuclear testing between 1946 and 1958, descendants of Marshall Island residents may have underappreciated genetic abnormalities, increasing their risk of birth defects. Methods: We conducted a retrospective cohort study of resident women with at least one singleton live birth between 1997 and 2013 in northwest Arkansas using state birth certificate data linked to data from the Arkansas Reproductive Health Monitoring System, a statewide birth defects registry. We calculated unadjusted and adjusted prevalence ratios (PR) and 95% confidence intervals (CI) from modified Poisson regression analyses for non-Hispanic (NH) whites, NH-blacks, Hispanics and Marshallese, using NH-whites as the reference group. Results: Of the 91,662 singleton births during the study period, 2,488 were to Marshallese women. Due to the relatively small number of Marshallese births, we could not calculate prevalence estimates for some defects. Marshallese infants had higher rates of congenital cataracts (PR = 9.3; 95% CI: 3.1, 27.9). Although the number of defects was low, Marshallese infants also had higher rates of truncus arteriosus (PR = 44.0; 95% CI: 2.2, 896.1). Conclusions: Marshallese infants may have increased risk of specific birth defects, but estimates are unstable because of small sample size so results are inconclusive.Larger population-based studies would allow for further investigation of this potential risk among Marshallese infants.