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Kazim Mavi and Ibrahim Demir

; TeKrony, 2003 ). The controlled deterioration (CD) ( Powell and Matthews, 2005 ) and accelerated aging (AA) ( Hampton and TeKrony, 1995 ) tests have been successfully used to rank and predict relative field emergence potential of seed lots in various

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Ibrahim Demir and Kazim Mavi

longevity of seed lots ( Powell and Matthews, 2005 ; TeKrony, 2003 ). Several such tests have been used to indicate emergence potential and longevity in crop seeds among which controlled deterioration (CD) and accelerated aging (AA) are widely used

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Jianhua Zhang and Miller B. McDonald

The accelerated aging vigor test subjects seeds to high temperatures (41°C) and relative humidity (about 100%) for short durations (usually 72 hours). These recommendations, however, have been developed for large-seeded agronomic crops and may be too severe for small-seeded flower crops that deteriorate rapidly during storage such as impatiens. We examined the effect of aging regime duration (48, 72, and 96 hours) and temperature (38 and 41°C) as well as relative humidity using three saturated salt solutions (KCl–87% RH, NaCl–76% RH, and NaBr–55% RH) on two commercial impatiens seed lots differing in seed vigor but not percentage germination. The greatest differences in percentage germination after 4 days were found among the treatments of 48 hours for KCl, 72 hours for NaCl, and 96 hours for NaBr. While any of these saturated salt solutions may be used in a commercial situation to determine impatiens seed vigor, we suggest that a total 7-day test period consisting of 72 hours aging at 41°C using saturated NaCl with germination being determined 4 days after aging is most convenient.

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S.T. Kester, R.L. Geneve, and R.L. Houtz

Damage and degradation of cellular proteins is observed during seed deterioration due to aging. L-isoaspartyl methyltransferase (EC 2.1.1.77) is an enzyme hypothesized to play a role in limiting and repairing aging-induced damage of proteins. Tomato seeds (Lycopersicon esculentum `New Yorker') were assayed for changes in L-isoaspartyl methyltransferase activity during accelerated aging and after osmotic priming. Accelerated aging of seeds for 1 to 4 days at 45°C and 100% humidity reduced germination from 94% to 71%, the mean time of germination (MTG) increased from 2.4 to 5.8 days and was accompanied by a correlative decrease in L-isoaspartyl methyltransferase activity R 2 = 0.90. Aged and untreated seeds were primed for 7 days at 20°C in darkness using aerated solutions of 3% KNO3 or polyethylene glycol 8000 (PEG) with equivalent osmotic potential (–1.25 MPa). Priming with KNO3 decreased the MTG but not germination percentage for untreated seeds. Priming did not affect L-isoaspartyl methyltransferase activity in untreated seeds but restored activity in aged seeds primed in KNO3 to levels near that of untreated seeds. Priming with PEG did not effectively improve the MTG or increase L-isoaspartyl methyltransferase activity. During germination, enzyme activity remained constant for 48 hours post-imbibition and then declined suggesting the enzyme was developmentally regulated and inactivated or degraded as radicle emergence occurred.

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Ibrahim Demir, Tuba Celikkol, Golge Sarıkamıs, and Ceren Eksi

development of normal seedlings under a wide range of sowing conditions ( McDonald, 1975 ). Tests are widely used in a number of agronomic and vegetable crops ( Hampton and TeKrony, 1995 ), but information in flower seeds is scarce. Accelerated aging is a well

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Keith S. Mayberry, Kent J. Bradford, and Vincent E. Rubatzky

A seedling disorder of broccoli (Brassica oleraceae L. var. italica) characterized by chlorotic cotyledons and delayed seedling growth is described. This disorder, termed “yellow cotyledon”, has been observed in field plantings under high temperatures with some broccoli seed lots. Yellow-cotyledon disorder can be observed in laboratory germination tests if they are conducted under illumination, where unaffected seedlings will develop green cotyledons. Little relationship was found between overall seed vigor and the expression of yellow cotyledon by use of early germination counts and accelerated aging tests, although the most severely affected seed lots had been stored for several years. Field trials in 2 years showed that although seedlings with yellow-cotyledon disorder developed into normal plants, maturity was delayed and total yields were reduced.

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Mustafa M.A. Elballa and D.J. Cantliffe

The effect of temperature on seedstalk development, seed yield and quality in carrot (Daucus carota L.) was investigated in growth chambers at constant day/night temperatures of 33/28, 28/23, 25/20, 23/18, 20/15, and 17/12 °C. Days to flowering, seedstalk height, number of umbels, and seed yield decreased linearly with increasing temperature from 17/12 to 33/28 °C. Continuous high temperature (33/28 °C) had a detrimental effect on germination as measured by a standard germination test and an accelerated aging test. Optimum germination of the progeny occurred at 20/15 °C; however, germination rate was faster when seeds matured at 23/18 °C. Seeds that developed at 33/28 °C produced seedlings with the lowest vigor, while those which developed at 20/15 °C produced seedlings with the highest vigor. Brief exposure of plants to 33/28 °C during anthesis or early seed development was as detrimental to seed yield as continuous exposure to 33/28 °C. Exposure to high temperature (33/28 °C) during late seed development had less effect on seed yield, and seed quality was improved. Progeny vigor was reduced greatly by seed development at continuous high temperature (33/28 °C), but was unaffected by brief exposure to 33/28 °C at anthesis, early, or late in seed development. These results suggest that high (33/28 °C) day/night temperatures during pollination, fertilization, or early stages of seed development can greatly reduce carrot seed yield and seed quality.

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Gokhan Hacisalihoglu

evaluate the effect of MC on warm-season turfgrass GP and mean germination time under optimum, 7- or 14-d accelerated aging conditions. Materials and methods Seed material and matriconditioning. Seeds of ‘Pensacola’ bahiagrass, ‘Princess’ bermudagrass, and

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Yai Ulrich Adegbola and Héctor E. Pérez

acrylic-accelerated aging container (156C, Hoffman Manufacturing, Inc.). We immediately assigned one of the trays at random to the container and transferred the container to an incubator (I-30-VL; Percival Scientific, Inc., Perry, IA) set at 41 °C with a

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Anwar A. Khan

ACC-derived ethylene production was used as an index of seed vigor of lettuce (Lactuca sativa L.), cabbage [Brassica oleracea (Capitata Group)], tomato (Lycopersicon esculentum Mill.), snap bean (Phaseolus vulgaris L.), and sweet corn (Zea mays L.) seeds. Seeds were aged at 40C and 93% relative humidity over saturated solution of KH2PO4 for various times to obtain seeds of differing vigor. Naturally aged lettuce seeds, differing in vigor, were also used. Depending on the seed type, 0.25 to 2 mm ACC (saturating dose) was needed to produce maximal amounts of ethylene. Seeds in the presence of ACC produced a much larger amount of ethylene than those in the absence of ACC, the ACC-derived ethylene could be detected before germination, and ACC had no adverse effect on germination. ACC-derived ethylene production paralleled vigor loss as determined by a decrease in percentage germination over a soak period required for complete germination of nonaged seeds (16 hours for lettuce, 24 hours for cabbage, and 48 hours for tomato and sweet corn), an increase in mean germination time (determined for lettuce only), and a decrease in seedling growth (determined for snap bean only). Second degree polynomial and logarithmic equations generated for the relationship of ACC-derived ethylene production to germination or growth parameters following seed aging, provided good to excellent fit. As a vigor test, the ACC-ethylene procedure has several advantages over the non-ACC ethylene procedure: It improves the sensitivity of the test by enhancing ethylene production, permits detection of small differences in vigor, and allows detection of ethylene before germination within a few hours of soaking. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).