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Rosanna Freyre, Amy C. Douglas, and Michael O. Dillon

Reciprocal crosses, both intraspecific and interspecific, were made among five Chilean species of Nolana (Solanaceae), a genus native to western South America. With the exception of N. paradoxa, plants of all species used were grown from mericarps collected from wild populations. Self-pollinations were generally not successful, suggesting obligate allogamy. A total of 333 hybridizations were performed, of which 109 were intraspecific and 224 interspecific. Successful intraspecific hybridizations, as measured by formation of fruits, were produced for N. acuminata (83%), N. elegans (94%), N. paradoxa (82%), and N. rupicola (100%), however viable hybrids were only obtained for N. paradoxa. Interspecific combinations resulted in over 80% fruit set, however, viable hybrid success ranged from only 1% to 5%. Crosses included N. elegans × N. paradoxa with 20 viable hybrids, N. paradoxa × N. elegans with two hybrids, N. paradoxa × N. rupicola with seven hybrids, and N. rupicola × N. paradoxa with five hybrids. Exceptions included crosses involving N. aplocaryoides, with up to 20% fruit set. Also, the combination N. paradoxa × N. aplocaryoides with five hybrids, had a 26% success. All interspecific hybrids obtained had N. paradoxa as one of the parents, which could be related to artificial selection for high germination frequency.

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Jimmy L. Tipton

Abstract

Light reduced final percentage of germination, maximum germination rate, and time to maximum germination rate of hulled creosotebush [Larrea tridentata (D.C.) Cov.] mericarps. The final percentage of germination declined at an osmotic stress greater than −0.4 MPa, but maximum germination rate increased at a stress greater than −0.6 MPa, and inflection time increased with increasing stress. Twice the recommended level of 3 fungicides tested had a negative impact on germination, and all fungicides delayed the time to maximum germination rate at all levels.

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Michael Olszewski, Wallace Pill, Thompson D. Pizzolato, and John Pesek

Germination studies indicated that increasing priming duration (-1.0 MPa at 20 °C for 7, 14, or 21 days) increased `Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex A.W. Hill] germination rate quadratically and seed moisture content linearly. A histological and anatomical study was conducted to identify and/or quantify principle mericarp organ or tissue volume changes influenced by priming duration. Embryo volume increased as priming duration increased from 7 to 21 days (0.014 to 0.034 mm3), and this was due more to radicle (0.007 to 0.022 mm3) than to cotyledon (0.006 to 0.011 mm3) growth. Concomitant with increased embryo volume was increased volume of the depleted layer (space formation, surrounding the embryo), from 0.038 after 7 days to 0.071 mm3 after 21 days, and increased hydrolysis of central endosperm (a thick-walled endosperm type). In nonprimed mericarps, central endosperm cells constituted 97% of the endosperm volume. The remaining 3% was comprised of 1% depleted layer and 2% distal endosperm (small, thin-walled, and irregularly shaped endosperm cells). During 7 or 21 days of priming, ≈10% or 40%, respectively, of central endosperm cells were hydrolyzed centrifugally around the embryo with a corresponding decrease in volume of central endosperm with thick cell walls. In addition, distal endosperm cells adjacent to the depleted layer, containing reserve materials, were digested of contents following 21 days priming, and sometimes, following 7 days priming. A long priming duration resulted in degradation of pericarp tissues, as indicated visually and by a decline in pericarp volume. We hypothesize that priming duration of parsley primarily influences radicle growth and centrifugal digestion and utilization of central and distal endosperm, resulting in a larger depleted layer required for embryo volume increases. Secondary events influenced by priming duration include cotyledon growth and degradation of pericarp tissues.

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Amy Douglas and Rosanna Freyre

Nolana is a diverse genus native to coastal deserts of Peru and Chile, with great potential for developing new ornamental cultivars. Low germination has been an obstacle to breeding efforts at the University of New Hampshire (UNH). Nolana fruits are comprised of unusual sclerified mericarps, each containing one or more embryos. Germination occurs with opening of funicular plugs on the mericarps. Under normal greenhouse conditions at UNH, germination success in eight Nolana species (N. adansonii, N. aticoana, N. humifusa, N. laxa, N. ivaniana, N. plicata, N. elegans, and N. rupicola) ranged from 0 to 0.05 seedlings/mericarp. We analyzed mericarp morphology, imbibition, and the effect of chemical and environmental germination treatments. SEM showed that soaking treatments create physical changes in mericarp morphology, exposing tracheid tubes in the funicular plugs. Mericarps were soaked in dye to track imbibition, confirming that this occurs through the tracheid tubes, and that additional scarification is not required. The following chemical treatments were unsuccessful in increasing germination: 0.1 N HNO3, 0.2 KNO3, conc. H2SO4, 10 mM or 1 μM ethephon. Gibberellic acid (1000 ppm) effectively increased germination in some species (up to 0.47 seedlings/mericarp). Mericarps stored dry for 2 years had significantly higher germination than fresh mericarps (0.55 seedlings/mericarp). Mericarps of N. aticoana were subjected to after-ripening treatments. Mericarps stored for 7 weeks at 35 °C and 75% RH showed significantly higher germination (0.36 seedlings/mericarp) than mericarps stored dry, or stored moist for 1-6 or 8-12 weeks. Our findings facilitate development of larger hybrid populations, thus increasing the efficiency of Nolana breeding programs.

Open access

J. L. Tipton

Abstract

Polynomial, monomolecular, logistic, and Gompertz growth curves were evaluated for their suitability as mathematical models for germination data. Germination of hulled or leached creosote bush [Larrea tridentata (DC.) Cov.] mericarps were used in the evaluation. The Gompertz model gave the best fit. Germination curves and germination rate curves gave similar patterns of response to results obtained by other methods, which suggests the Gompertz model may have application in germination data analysis. Hulling improved germination over leaching intact mericarps. Nine hours was the optimum leaching duration for intact mericarps.

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Michael W. Olszewski, Wallace G. Pill, and Thompson D. Pizzolato

`Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex. A.W. Hill] schizocarps were osmotically primed in polyethylene glycol at -1.0 MPa for 7 days at 20 °C. The smaller of the two mericarps within a parsley schizocarp had lower germination percentage, but similar rate and synchrony of germination. Osmotic priming increased germination percentage, rate, and synchrony, irrespective of mericarp half. This promotive effect of priming on germination was associated with embryonic advancement as indicated by a doubling of radicle and cotyledon volumes, without changes in lengths of these organs. Periclinal divisions of the lateral expansion meristem, distinct in primed radicles but indistinct in nonprimed radicles, led to radial alignment of the cortical cells and a doubling of cortical volume and thereby increased radicle volume. Each embryonic cotyledon of primed mericarps had three distinct procambial bundles that differentiated along most of the cotyledon length, while nonprimed cotyledons had from zero to three that differentiated only a short way into the cotyledon. Priming increased coyledonary procambium length by 5-fold and volume by 11-fold. Increased embryonic growth due to priming was associated with greater endosperm depletion adjacent to the embryo. The schizocarps frequently separated or partially separated into component mericarps during priming, indicating a weakening of pericarp tissue along the commissural suture and possibly elsewhere.

Open access

Yongjun Yue and John M. Ruter

fertility. The plants are small perennial shrubs with unique axillary red or red-purple flowers and five petals. The mericarps are reticulate-rugose, the adaxial leaf surfaces have simple trichomes on the lamina and stellate trichomes on prominent veins

Open access

Yongjun Yue and John M. Ruter

alternate carpels abort during their development. The fruits of Pavonia are composed of five mericarps, with each containing a single seed. In Pavonia sect. Pavonia and P. subsect. Lebretonia , the mericarps are indehiscent and variously ornamented

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Sandra B. Wilson, Gary W. Knox, Keona L. Muller, Rosanna Freyre, and Zhanao Deng

). Seed production, viability, and germination. Within 8 to 12 weeks, each of the eight cultivars evaluated produced fruit characterized as an oblong-linear schizocarp splitting at maturity into two mericarps ( Munir, 1992 ). However, there were

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Dao-Jing Wang, Jing-Wen Zeng, Wen-Tao Ma, Min Lu, and Hua-Ming An

:2409–2414 Celep, F. Kahraman, A. Atalay, Z. Doğan, M. 2014 Morphology, anatomy, palynology, mericarp and trichome micromorphology of the rediscovered turkish endemic Salvia quezelii (Lamiaceae) and their taxonomic implications Plant Syst. Evol. 300 9 1945 1958