Seed dormancy and longevity variability of Hirschfeldia incana L. during storage

Abstract

We studied the variability of germination, dormancy and viability loss of Hirschfeldia incana seeds in relation to seed size. Seeds were stored at 35°C under humid [75% relative humidity (RH)] or dry (33% RH) conditions. Seed germination and electrolyte leakage were evaluated periodically. Small seeds had lower longevity at humid or dry storage conditions (5 or 407 days, respectively) than large or intermediate seeds (7–9 or 536–727 days, respectively). Moreover, H. incana shows variability in seed dormancy related to seed size within a population, with small seeds having lower dormancy (13%) than intermediate (50%) or large seeds (72%). Dormancy was partially released after a short storage at 35°C and humid conditions. Under dry storage conditions, endogenous dormancy cycles were observed for over a year, and longer times of storage had a dormancy-breaking effect through dry after-ripening. Results suggest a dual strategy producing non-dormant seeds with low longevity that will germinate immediately after dispersal, and seeds with greater longevity that will delay germination. Membrane permeability increased linearly with ageing at both humid and dry storage (R2 = 0.60). Small seeds showed greater conductivity than intermediate or large seeds (0.7, 0.4 or 0.3 mS g–1 dry weight, respectively, at the 80% germination). The conductivity test could be used to evaluate the quality of H. incana seeds and would allow us to identify dormant (non-germinating) seed lots as viable. However, the influence of storage conditions and variability within a seed population on seed longevity should be taken into account when evaluating seed quality.

A rapid and sensitive method to assess seed longevity through accelerated aging in an invasive plant species

“…This result coincides with those obtained in Jatropha curcas L. seeds, which showed a faster deterioration in AA tests over water in contrast with using a saturated salt solution [44]. Similar results were obtained with Hirschfeldia incana when comparing humid (75%) and dry (33% RH) storage at 35 °C, where humid storage decreased almost 100 times seed longevity [45]. In fact, resultant products of non-enzymatic modifications of protein structures through glycation found in accelerated aged soybean seeds were formed most rapidly in seeds at high humidity [46].…”

Viability and vigour loss during storage of Rudbeckia mollis seeds having different mass: an intra-specific perspective

“…Loss of germination potential results from accumulated ageing damage that occurs during seed storage or applied stresses. Growing evidence indicates relationships between intra-specific seed mass variation and seed deterioration associated with high temperature and relative humidity stress (Franks et al, 2019; Genna and Pérez, 2016; Guzzon et al, 2018; Mira et al, 2019). We examined water sorption characteristics of mass-separated R. mollis seeds and then evaluated responses of each mass class to various storage and stress treatments.…”

“…There is a positive exponential relationship between seed water content and seed deterioration rate for seeds held at relative humidity greater than about 30% (Ellis et al, 1990; Walters et al, 2010). Mira et al (2019) found that smaller seeds of H. incana contained more water and deteriorated more rapidly than larger seeds. However, R. mollis mass classes did not differ significantly for seed water content at higher RH, meaning that the slower deterioration observed in seeds of the heavy seed class stored in the shed should not be attributed to water content per se.…”

“…Recent studies show that lower mass seeds within populations of Aegilops, Rudbeckia and Brassica expressed greater longevity than higher mass seeds following warm, humid stress (Genna and Pérez, 2016;Guzzon et al, 2018;Franks et al, 2019). To the contrary, Mira et al (2019) found greater longevity in higher mass seeds within a population of Hirschfeldia incana. These important studies share certain commonalities.…”

“…These methods are used to discern seeds with a high and low capacity for germination or seedling establishment and to generate a relative vigour index (Baalbaki et al, 2009). Vast literature exists showing how seed scientists have adapted these techniques to study seed deterioration and model potential seed longevity (Baalbaki et al, 2009 [references therein]; Probert et al, 2009; Genna and Pérez, 2016; Guzzon et al, 2018; Franks et al, 2019; Mira et al, 2019).…”