Primed Lettuce Seeds Exhibit Increased Sensitivity to Moisture Content During Controlled Deterioration

Abstract

<jats:p>The Ellis-Roberts seed viability equation is used to predict seed survival after storage at specified temperatures and moisture contents. Seed priming, which can break dormancy and accelerate germination, can also reduce seed storage life. Because primed seeds were not used in developing the Ellis-Roberts equation, the reciprocal nature of specific seed moisture content (MC, fresh weight basis) and temperatures that applies to nonprimed lettuce (<jats:italic>Lactuca sativa</jats:italic> L.) seeds may not apply to primed seeds. To determine how priming affects lettuce seeds in relation to the viability equation, an experiment was conducted using two cultivars, ‘Big Ben’ and ‘Parris Island Cos’. Seeds primed in polyethylene glycol 8000 (–1.45 MPa, 24 h at 15 °C) and nonprimed seeds were first adjusted to 6% and 9% moisture contents and then stored at 48 and 38 °C for up to 30 days, respectively. These storage conditions (6% MC and 48 °C; 9% MC and 38 °C) were predicted by the viability equation to result in equal longevities. Subsequent viability assays at 20 °C revealed that nonprimed seeds in both storage environments exhibited similar losses in viability over time, thus validating the Ellis-Roberts equation and the use of these conditions to apply different but equal aging stress. Primed seeds of both cultivars deteriorated faster than nonprimed seeds as expected. However, primed seeds did exhibit different rates of deterioration between the storage environments. Primed seeds stored at 9% MC and 38 °C deteriorated faster than primed seeds stored at 6% MC and 48 °C. The rate of decline in probit viability percentage was three times greater in primed ‘Big Ben’ seeds stored at 9% MC and 38 °C than for those stored at 6% MC and 48 °C (–1.34 versus –0.26 probits per day, respectively). ‘Parris Island Cos’ seeds stored at 9% MC and 38 °C had twice the rate of deterioration that those stored at 6% MC and 48 °C (–1.19 and –0.49 probits per day, respectively). The results indicate that primed lettuce seeds were more sensitive to the adverse effects of higher seed MC than were nonprimed seeds during storage at elevated temperatures.</jats:p>

Seed Priming: New Comprehensive Approaches for an Old Empirical Technique

“…The major drawback of priming is that it reduces the longevity of primed seeds as compared with the nonprimed seeds [190][191][192]. Storability of primed seed material is consequently reduced, and this results in higher costs for material maintenance for farmers and seed companies.…”

Benefits of rice seed priming are offset permanently by prolonged storage and the storage conditions

“…Seed priming reduces the longevity of primed seeds enormously as compared with non-primed seeds 6 7 8 9 . Primed sweet corn seed exhibited poor germination and seedling growth performance after 3 months of storage at 25°C than non-primed seed 7 .…”

“…Delayed and lower germination was recorded in primed tomato seeds, when stored at 30°C for 6 months as compared with the control 6 . Primed lettuce seeds were particularly prone to reduced longevity relative to non-primed seeds when stored under high temperature and high moisture conditions 8 9 . Even under mild storage conditions (45°C at 50% relative humidity), primed lettuce seeds exhibited slower and less synchronous germination than the non-primed seeds in as little as 14 d 10 .…”

Storage performance of primed bell pepper seeds with 24‐Epibrassinolide

“…Long‐term storage, particularly under environmentally adverse conditions, can be more harmful to primed seeds because, during priming, the seed storage reserves are mobilized into simple compounds that are not resynthesized into a storage reserve. Thus, primed seeds are more prone to deterioration and should be stored under special environmental conditions, that is, the temperature and relative air humidity for the storage of primed seeds should be lower than that normally used for the storage of unprimed seeds (Hill, Cunningham, Bradford, & Taylor, 2007; Marcos‐Filho, 2016; Nascimento, 1998). If this measure is taken, the effects of priming will be consistent throughout storage.…”