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    Electrical conductivity of seed soak water predicts seedling emergence and seed storage potential in commercial seed lots of radish
    (Ista-Int Seed Testing Assoc, 2014) Mavi, K.; Mavi, F.; Demir, I.; Matthews, S.
    Electrical conductivity (EC) measurements of seed soak water after 17 and 24 hours of nine commercially acceptable seed lots (79-100% standard germination) of the salad radish cultivar Findik were positively correlated with the mean time taken to emerge (MET) and negatively with final emergence (%) in sowings in modules and in the field. EC after 17 hours was closely related to both the means of the two sowings (R-2 = 0.877; P < 0.001), and standard germination after 12 months storage (R-2 = 0.868, P < 0.001). Thus increased levels of electrolyte leakage were associated with slower and lower emergence and with poorer storage potential. The mean germination time (MGT) to radicle emergence (RE) during germination at 20 C was similarly correlated with seed performance. The slower seed lots were to RE, the slower and lower was the emergence and the poorer the storage potential. EC after 17 hours was positively related to MGT (R-2 = 0.799; P < 0.01) and negatively related to germination after controlled deterioration, a measure of seed age (R-2 = 0.741; P < 0.01). Seed lots showing high levels of leakage were slower to RE and were more deteriorated. High leakage was associated both with seed lots having high percentages of dead seeds (no RE) and seeds producing abnormal seedlings, and also with lots containing seeds that were slow to produce an emerged radicle. EC is suggested as a potential one-day routine test of physiological seed quality for radish and the overall findings are discussed in relation to the effects of deterioration brought about by seed ageing.
  • Küçük Resim
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    Mean germination time estimates the relative emergence of seed lots of three cucurbit crops under stress conditions
    (Ista-Int Seed Testing Assoc, 2010) Mavi, K.; Demir, I.; Matthews, S.
    A wide range of seedling emergence in commercial seed lots of watermelon (10 lots), melon (10 lots) and cucumber (9 lots), all with standard germinations above 98%, was seen in low temperature emergence (LTE). high temperature (HTE) and an 8 cm deep sowing (MSE) in the field and in salt stress conditions (SSE) in trays at 20 degrees C. Final emergence was closely related to both the rate of emergence, measured as mean emergence time (MET; the reciprocal of the rate of emergence), and to the mean germination time (MGT; the reciprocal of the rate of germination) for physiological germination (2 mm radicle) in the laboratory at 25 degrees C. Slower germinating and emerging lots, so-called low vigour lots, had lower levels of emergence in all sowings. Single early counts of physiological germination identified low vigour lots for all three species and are suggested as a quick routine test. The physiological age of the seed lots, determined using accelerated ageing (45 degrees C in 100% relative humidity) and controlled deterioration (45 degrees C and 20 or 24% moisture content), was significantly related to MGT which was higher (i.e. germination was slower) in physiologically older seed. Previous work suggests that cucurbit seeds appear to retain germination capacity over several years although ageing is reflected in a slower rate of germination (high MGT). MGT can also he described as the length of the lag period from the start of imbibition to radicle protrusion. We propose that this period is needed for the repair of the effects of ageing and is therefore longer in aged seeds.
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    Öğe
    Rate of radicle emergence and leakage of electrolytes provide quick predictions of percentage normal seedlings in standard germination tests of radish (Raphanus sativus)
    (Ista-Int Seed Testing Assoc, 2016) Mavi, K.; Powell, A. A.; Matthews, S.
    The potential of radicle emergence (RE) and electrical conductivity (EC) tests to predict normal seedlings (%) was investigated in ten commercially available lots of radish. The mean germination time (MGT), calculated from frequent counts of RE, and one count of RE at 48 hours, consistently predicted germination (eight out of nine R-2 >= 0.900). EC measurements of seed soak water (3 x 100 seeds in 40 ml distilled water) after 1, 3, 5, 17 and 24 hours soaking in four tests at 20 degrees C were also highly predictive of normal seedlings (%) and MGT (25 out of 28 R-2 values >= 0.80). EC readings from 20 single seeds (five hours in 8 ml water at 20 degrees C) of each lot, followed by germination at 10 C revealed the highest leakage from dead seeds and seeds that produced abnormal seedlings, followed by slow germinating (to RE) seeds that produced normal seedlings. Hydration treatment of single seeds from three lots (five hours at 20 degrees C, then dried back) reduced leakage and MGT, which are interpreted as the result of metabolic repair of deteriorated membranes and support the ageing/repair hypothesis. Both EC and RE tests therefore provide quick and repeatable predictions of percentage normal seedlings in radish.