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Jia Liu, Tingting Xue, and Yongbao Shen

tungstate [a specific NR inhibitor ( Rockel et al., 2002 )] were used at different hours during imbibition to investigate the effects of endogenous NO on seed dormancy and germination. Materials and methods Seeds were collected from empress trees in Nanjing

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Shahid N. Chohan and Terence A. Brown

HPLC was used to measure nucleotide pools in tomato seeds during the 3 h following imbibition in water. In dry seeds, nucleotides were predominantly in the form of monophosphates. During the first 2 h post-imbibition, the monophosphate levels declined and there were sharp increases in the amounts of diphosphates, followed by triphosphates. Between the 2nd and 3rd h, the di- and triphosphate levels continued to increase and the monophosphate levels began to recover, especially in the case of UMP—presumably the result of degradation of unwanted mRNAs left over from the maturation phase of seed development. The adenylate energy charge increased during imbibition and, within 3 h, reached a value close to that of normal active tissue.

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Olga A. Kildisheva, R. Kasten Dumroese, and Anthony S. Davis

prevent germination. Physically dormant seeds have a palisade layer of lignified cells that prevents water imbibition ( Corner, 1951 ; Vazquez-Yanes and Perez-Garcia, 1976 ). Although a number of species in the Sphaeralcea genus have been observed to

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Hector E. Pérez

-Segovia et al., 2003 ). For example, Moussa et al. (1998) suggested that the thick pericarps of doum palm ( Hyphaene thebaica ) are water impermeable. Yet, these authors provided no evidence that imbibition is blocked due to the pericarp. On the contrary

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Claudia A. Espinosa-Leal and Silverio Garcia-Lara

of four treatments that used four glass jars (capacity, 110 mL) each and a final treatment with 12 seeds per treatment. The treatments were as follows: treatment 1, 10% SSW and 1:10 MS 10% SSW; treatment 2 (SI), seeds imbibed in distilled water for 16

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D. H. Schmidt and W. F. Tracy

Abstract

Seed leachate conductivity (SLC) has been evaluated as a possible method of measuring seedling vigor in sweet corn (Zea mays L.) and other crops. It is known that genotypes leak solutes at different rates. Thus, it is important to determine if the different rates of leakage result in different SLC determinations when SLC is measured after various lengths of imbibition. A study was conducted using near-isogenic lines of three inbreds (C68, P39M94, and Ia5125a) in combination with five endosperm types, sugary dull (su du), sugary sugary-2 (su su2), sugary dull waxy (su du wx), shrunken-2 (sh2), and sugary (su), to evaluate the effect of length of imbibition and the interaction of imbibition length and endosperm type and inbred background on conductivity. Readings were taken at 0, 2, 4, 6, 8, 10, 12, 14, and 24 hr after the start of imbibition. Conductivity was affected by length of imbibition, inbred background, and endosperm-type main effects and interactions of these effects. Conductivity increased with increasing time after imbibition. Ranking of endosperm types within each inbred was stable by 2 hr after imbibition, although differences were not always significant. Thus, the interaction effects were due to an increasing separation over time and not to a change in ranking of the genotypes. However, means separation was greatest at 24 hr after imbibition.

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Sharon Sowa and Eric E. Roos

Infrared spectroscopy was used to measure biochemical changes during bean (Phaseolus vulgaris L.) seed imbibition. Transmission spectroscopy of excised embryonic axes revealed changes in lipid phase (gel to liquid crystalline) and protein secondary structure within the first 15 min of hydration. Spectral changes in seed coats, cotyledons, and axes during the first 2 hr of imbibition (measured in vivo) were detected using photoacoustic sensing. Onset of seed respiration could be detected as early as 15 min after addition of water. CO2 production, demonstrated by the appearance of a double peak centered at 2350 cm-1, increased with time of imbibition. Infrared photoacoustic spectroscopy of intact seeds holds promise as a method for non-invasive viability assessment.

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H. J. Hill, A. G. Taylor, and T.-G. Min

Abstract

The objective of this study was to determine the relationship between seed density and seed quality of vegetable seeds hydrated by imbibing or priming procedures. Species studied were: lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), onion (Allium cepa L.), cabbage (Brassica oleracea var. capitata L.), and carrot (Daucus carota L.). Seeds of each crop were soaked in either aerated distilled water at 25C (imbibed seeds) or polyethylene glycol (PEG) 8000 at 15C (primed seeds). After soaking, seeds were separated into density classes with a float-sink procedure using aqueous solutions of Maltrin 600 (Maltrin 500 for lettuce) with 0.02 g·cm−3 density increments. Significant (P > 0.01) positive relationships were determined between seed density classes and germination percentages for lettuce, tomato, and onion seeds, whether separated after imbibition (R 2 = 0.93, 0.83, and 0.66, respectively) or after priming (R 2 = 0.95, 0.94, and 0.91, respectively). High-density classes of hydrated lettuce, tomato, and onion seeds in either the imbibed or primed treatment usually exhibited faster and more uniform rates of radicle emergence and, after 6 days, had longer hypocotyls (cotyledon for onions) than low-density classes. The significant quality differences exhibited among the density classes of lettuce, tomato, and onion seeds after priming will enable seedlots of these species to be upgraded by discarding the low-density, poor-quality seeds.

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William R. Krul

Abstract

I noticed that seeds of soybean [glycine max (L.) Merrill cv. Dunn] remained dry and brittle after a prolonged period of rain, even though the senescent pods were thoroughly wetted. This observation led me to hypothesize that pods might contain substances which block imbibition of water by seeds.

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Mehrassa Khademi, David S. Koranski, and Joan Peterson

Seeds of Primula acaulis (L.) J. Hill `Dukaat Helderrose' were imbibed for 48 h at 18C, and Maltrin 600 solution was used to separate them into density classes of 1.10, 1.12, 1.14, 1.16, and 1.18 g·cm-3. Seeds were rinsed, air-dried for 48 h at 22C, and germinated at 18C; 80% were separated into density classes between 1.16 and 1.18 g·cm-3. Percentages of germination and high-vigor seedlings were significantly greater for seeds with densities >1.14 g·cm-3. Soluble protein concentration increased with density, whereas insoluble protein concentration was unchanged. Distinct protein groups with estimated molecular weights of ≈50, 33, and 25 kDa were present in the protein profile of nonseparated imbibed seed. These proteins were most abundant at densities ≥1.16 g·cm-3. The 25-kDa protein was present only in higher density seed. Presence of an additional 14-kDa protein was noted in the insoluble protein profile. Certain proteins in the soluble protein fraction maybe used to test for seed vigor.