Volume 35, No. 2, 2013

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Download abstracts (free download) from oral and poster presentations given at the  103rd Association of Official Seed Analysts and the 90th Society of Commercial Seed  Technologists (AOSA/SCST) annual meeting held in Boise, Idaho on May 19–23, 2013

(pp. 167-175)
Effects of Priming Techniques on Sunflower (Helianthus annuus) Germination and  Seedling Establishment
Afsane Pirmani, Tooraj Mir-Mahmudi, Nabi Khaliliaqdam*, Saman Yazdan-Sta and Soran Sharafi
Seed priming has been successfully used to improve germination and seedling establishment of many vegetables and field crops. Laboratory tests and field experiments were conducted in 2011 and 2012 at the Urmia Research Station, West Azerbaijan, Iran, to evaluate the effects of hydro-priming, halo-priming with 2% KNO3, and osmo-priming with ZnSO4 (200 mM Zn) and KH2PO4 (50 mM P) on seedling vigor and field emergence of sunflower.

Priming significantly improved seed germination, germination rate, seed vigor index, shoot, root and seedling dry weights, and reduced mean germination time and electrical conductivity of seed leachates, compared to the unprimed control. Hydro-priming was more effective in improving all studied parameters compared to priming with chemical salts. Effects of priming with ZnSO4 on germination traits, seed vigor and seedling dry weight were more pronounced than the effects of other halo-priming and osmo-priming treatments. Priming improved seedling emergence, emergence rate and emergence time. Priming with water and KH2PO4 resulted in higher seedling emergence and establishment in the field, compared to the control and priming with KNO3 or ZnSO4. Mean seedling emergence time was also reduced by priming, particularly hydro-priming. Hydro-priming is therefore a simple, low cost technique for improving seed germination and seedling emergence of sunflower.
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(pp. 177-188)
Ascorbic Acid Attenuates Seed Aging Effects on Cowpea Germination and Seedling Establishment
Jean Carlos de Araújo Brilhante, Alexandre Bosco de Oliveira* and Joaquim Enéas-Filho
The objective of this experiment was to assess the effects of exogenous ascorbic acid application on the vigor of cowpea (Vigna unguiculata) seeds subjected to aging and salinity.

Seeds were aged for 72 h at 45 °C and 99% RH, in the dark, then germinated in paper imbibed with either deionized water (T2), 100 mM NaCl (T3), 0.85 mM ascorbic acid (T4), or 100 mM NaCl + 0.85 mM ascorbic acid (T5), in addition to a control treatment (T1; non-aged seeds with deionized water). T2 and T3 affected germination stages, reducing dry mass, membrane integrity and seed germination. T4 mitigated the effects of artificial aging on germination and vigor, resulting in a higher emergence speed index (ESI) and water content, as well as lower mean emergence time (MET) of seedlings. T5 reduced fresh mass, increased seed electrical conductivity and slowed germination, with lower ESI and higher MET. Results suggested that ascorbic acid application could mitigate the effects caused by aging, but was not able to attenuate the toxic effects of NaCl on aged cowpea seeds.
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(pp. 189-198)
Phenotype and Seed Production among Hyacinth Bean (Lablab purpureus) Accessions Rescued Using Hydroponic Techniques
J.B. Morris
Hyacinth bean is a legume used as a vegetable, forage and ornamental plant. Many accessions do not flower during their juvenile period in Byron, Georgia. Other accessions produce few seeds when regenerated in the field. This study was conducted to develop a hydroponic cloning and nutrient film technique (NFT) for seed regeneration from juvenile, freeze-sensitive hyacinth bean accessions and a low seed-producing accession. 

Twenty-five juvenile and freeze-sensitive accessions were planted at Byron, GA during 2011. Four mature stem cuttings per accession with 3 true leaves were placed in a hydroponic cloning system inside a greenhouse during the fall of 2011. Most cuttings developed healthy root systems after 1–2 weeks. Two to 4 well-developed stem cuttings per accession were transplanted to potting soil and placed in a greenhouse. Fourteen 30-d-old seedlings from a low seed-producing accession grown in potting soil were placed in an NFT system inside a high tunnel during the first week of May, 2011. Seed numbers ranging from 20 to 1,127 per accession were regenerated from clones, while 1,629 seeds were regenerated from plants growing in the NFT system. The coefficient of variation for seed number was 59%, indicating fairly low variation. Cluster analysis grouped most accessions into well-defined phenotypes based on plant size. Principal component analysis indicated that the first principal component was most correlated with branching and seed yield. Hydroponic cloning and NFT were successful in rescuing juvenile and freeze-sensitive accessions for seed regeneration and consequent evaluation of  phenotypic variation.
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(pp. 199-211)
Effect of the Dormancy Mechanism on Seed Quality of ‘NK Churrinche’ White Clover  (Trifolium repens)
A.A. Galussi*, M.E. Moya, F.D. Zuriaga, L.R. Zimmermann and R. Basso
The seed coat of white clover seeds (Trifolium repens L.) is one of the factors affecting seed imbibition, causing irregular germination as well as abnormal seedlings and hardseededness. The aim of the present work was to determine the level of dormancy in white clover seeds in terms of hydration speed, moisture content, weight and germination, using seeds from two crop harvests in Argentina.

White clover seeds, cv. ‘NK Churrinche’, with physical dormancy had lower moisture content, lower weight and greater viability than non-dormant seeds. The moisture content of dormant seeds suggested better storability than non-dormant seeds. Water permeability varied among seeds, reflecting deep levels of physical dormancy, which in turn influenced seed physiological quality.
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(pp. 213-224)
Weathering Damage in Soybean Seeds: Assessment, Seed Anatomy and Seed Physiological Potential
Victor Augusto Forti*, Cristiane de Carvalho, Francisco André Ossamu Tanaka and Silvio  Moure Cicero
Weathering damage in soybean (Glycine max) seeds wrinkles the cotyledons, cracks the seed coat and causes tissue death. The objective of this study was to assess weathering  damage and relate damage severity with seedling symptoms and loss of viability, and show modifications of seed tissues with weathering damage using scanning electron microscopy (SEM).

Two soybeans seeds lots, cv. ‘TMG115-RR’, were subjected to  X-ray and tetrazolium (TZ) testing and seedling assessment, to assess weathering damage. Moreover, seeds with or without weathering damage were inspected using SEM. X-ray image analysis as well as TZ and seedling assessment tests confirmed that weathering damage interfered with seed physiological potential, varying according to the extent and location of the damage. SEM images showed that the seed coat hourglass cells occurred near the hilum region and gradually decreased until they disappeared opposite to the hilum region, a region where typical wrinkles caused by weathering damage are observed. On the cotyledons, the cells in damaged seeds appeared lengthened and compressed, probably accounting for cell death in the damaged region.
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(pp. 225-236)
Do Drought and Salinity Stresses Have Similar Effects on Thyme Germination and Seedling Growth?
Hamid Reza Eisvand* and Leyla Ghorashi Kalibar
Iso-osmotic potentials using PEG-6000 and NaCl solutions (0, −2, −4, −6, −8, −10 and −12 bar) were used for germination of Thymus fedtschenkoi, T. migricus and T. daenensis. At iso-osmotic potentials, seeds in saline solutions germinated at a higher rate compared to those incubated in PEG-6000 solutions.

Germination significantly decreased at −4 bar and dropped to zero at −10 bar under drought, while under salinity it decreased at −8 bar but did not fall to zero even at −12 bar. Under both salinity and drought, effects on germination and seedling development parameters were the same at low stress levels (−2 bar), but differed at higher stress levels. When exposed to salinity stress, germination of T. migricus was lower than that of T. daenensis and T. fedtschenkoi. Root branching decreased due to  both drought and salinity, and the maximum number of secondary roots was observed in  T. daenensis seedlings, while the lowest was observed in T. fedtschenkoi seedlings. Early  seedling growth was more sensitive to drought and salinity than seed germination. Germination and early growth of thyme seedlings was more sensitive to drought than salinity. Differences in response of seeds and seedlings to drought and salinity at the same osmotic potential was probably due to differences in molecular size of PEG and NaCl, resulting in different rates of entrance of these molecules into cells, consequently affecting water uptake of cells.
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(pp. 237-250)
Occurrence and Trends of Weed Seed and Ergot Contaminants in Oregon Grown Poa  pratensis and Poa trivialis Seed Lots
Stephen C. Alderman*, Sabry G. Elias and Andrew G. Hulting
Oregon is well known for seed production of the amenity grasses Poa pratensis (Kentucky bluegrass) and P. trivialis (rough bluegrass). However, little is known about weed seed and ergot contamination of certified Oregon Poa spp. seed.

This study was conducted to assess  the diversity and frequency of occurrence of weed seeds and sclerotia of the fungus Claviceps purpurea (ergot) in certified seed lots of P. pratensis and P. trivialis based on purity analysis at the Oregon State University Seed Laboratory during 1986–1995 and  2002–2012. For P. pratensis, 155 different weed seed contaminants were detected, with 113 identified to species, 39 to genus and 3 to family. For P. trivialis, 26 contaminants were  identified to species and 14 to genus. Between 2002–2012, the percentage of seed lots per year with no weed contaminants ranged from 48–75% and 43–68% for P. pratensis and P.  trivialis, respectively, indicating consistent high quality standards for Oregon certified  seed. Between 1985–2012, the number of new contaminants in P. pratensis increased at the rate of three per year. In P. trivialis, only one new contaminant species was detected after 2007. The percentage of P. pratensis or P. trivialis seed lots with ergot ranged from  22–61%, and 0–10% respectively, depending on year. This study documented a wide and increasing diversity of weed seed contaminants, especially in P. pratensis, and revealed that although the level of ergot from year to year is variable, ergot remains a persistent problem in P. pratensis seed production fields and as a post-harvest seed contaminant.
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(pp. 253-260)
Temperature and Light Requirements for Geoffroea decorticans Germination
M. G. Pece*, M.T. Sobrero and M.M. Acosta
This work aimed to determine the optimal temperature and influence of photoperiod on the germination process of Geoffroea decorticans seeds, a multiple-use woody species. We  used seeds from individual plants located in Río Primero, Córdoba.

The seeds were  sown on paper towels in groups of 25, placed in germination chambers and tested under nine temperature regimes: 10, 15, 20, 25, 30, 35, 40, alternating 30/20 and alternating 35/15 °C ± 2 °C, and two light conditions, a 12/12 h (light/dark) photoperiod and constant  darkness.  The effects of a 12/12 h photoperiod were studied on germination, time to 50%  germination, germination velocity and light-related germination, while only percentage  germination at the end of the test was evaluated under constant darkness. Germination of G. decorticans was higher than 50% within the 20–40 °C temperature range and at the alternating temperatures tested. The highest percentage germination (95%) was recorded  at 30/20 °C, but was not significantly different from those occurring at 25 (92%), 30 (90%),  35 (85%), or 35/15 °C (83%). Therefore, seeds of G. decorticans could germinate within a  wide range of temperatures and were light-neutral, although the highest germination  occurred under alternating light conditions.
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(pp. 261-265)
A Mechanical X-ray Imaging Device for Seed Analysis
R.M. Craviotto, M.R. Arango, A.R. Salinas*, R. Gibbons and C.V. Gallo
The aim of this work was to develop a specific X-ray machine to be used not only for research, but also for routine seed analysis. The machine consisted of an X-ray tube support column, tube stand, tube case, X-ray tube with a beryllium window, collimator, power supply, and grid cabinet.

The machine had a 0–50 KVp and 0–300 mA range and utilized 18 × 22 cm conventionally developed radiographic plates. The resulting X-ray images could be scanned and/or photographed to generate digital files. Diagramming radio graphic patterns for each species could be a very helpful tool for the interpretation of seed quality tests. The machine, called RUTAX, used a non-destructive method and had potential as a useful tool for evaluating a wide variety of seed and fruit species with different structural characteristics, allowing frequent and fast monitoring with a high level  of diagnostic reliability.
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