Seed development and maturation in early spring-flowering Galanthus nivalis and Narcissus pseudonarcissus continues post-shedding with little evidence of maturation in planta

Background and Aims: Seeds of the moist temperate woodland species Galanthus nivalis and Narcissus pseudonarcissus, dispersed during spring or early summer, germinated poorly in laboratory tests. Seed development and maturation were studied to better understand the progression from developmental to germinable mode in order to improve seed collection and germination practices in these and similar species. Methods: Phenology, seed mass, moisture content, and ability to germinate and tolerate desiccation were monitored during seed development until shedding. Embryo elongation within seeds was investigated during seed development and at several temperature regimes after shedding. Key Results: Seeds were shed at high moisture content (> 59%) with little evidence that dry mass accumulation or embryo elongation were complete. Ability to germinate developed prior to the ability of some seeds to tolerate enforced desiccation. Germination was sporadic and slow. Embryo elongation occurred post-shedding in moist environments, most rapidly at 20C in G. nivalis and 15C in N. pseudonarcissus. The greatest germination also occurred in these regimes, 78 and 48%, respectively, after 700 d. Conclusions: Seeds of G. nivalis and N. pseudonarcissus seeds were comparatively immature at shedding and substantial embryo elongation occurred post-shedding. Seeds showed limited desiccation tolerance at dispersal

Changes in germinability, desiccation tolerance and seed quality during embryogenesis and seed development in bean (Phaseolus vulgaris L.) and wheat (Triticum aestivum L.) And the factors influencing these physiological processes

Available from British Library Document Supply Centre- DSC:DX188556 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Pre-zygotic parental environment modulates seed longevity

The potential for the pre-zygotic plant growth environment to play a role in determining seed longevity was investigated for a species that inhabits arid to semi-arid Australia. Seed longevity is particularly important for wild populations in fluctuating environments because the longer a seed-lot is able to survive in the soil seed bank the more likely it is to buffer the population from unpredictable environments. Thus Wahlenbergia tumidifructa plants received wet or dry soil moisture within a warm or cool glasshouse until flowering. Seeds subsequently produced by flowers that opened on the day that plants were moved to a common environment were collected at maturity and longevity assessed by controlled ageing at 60% relative humidity and 45 degrees C. Mean seed longevity was similar for seeds produced by plants that grew in warm-wet, warm-dry and cool-dry conditions (P(50) of about 20 days), but extended for plants in cool-wet conditions (P(50) = 41.7 days). Cool temperatures resulted in seeds with a wider distribution of lifespans (sigma = 20 days) than warm conditions (sigma = 12 days); the large sigma caused the extended P(50) for cool-wet plants, but not cool-dry as a result of a concomitant reduction in initial seed germination (K(i)). After moving to the common environment, all plants generated new vegetative material, which went on to produce seeds with similar longevity (P(50) approx. 20 days) irrespective of original environment. Visible phenotypic responses of the parent to environmental conditions correlated with longevity and quality parameters of the progeny seeds, suggesting that a parental effect modified seed longevity. Our study provides novel empirical data showing that environmental conditions expected under climate change scenarios may potentially cause seed longevity to decline for a species that inhabits arid to semi-arid Australia. These negative impacts on population buffering may weaken the storage effect mechanism of species coexistence in fluctuating environments

Inter-population variation in seed longevity for two invasive weeds: Chrysanthemoides monilifera ssp monilifera (boneseed) and ssp rotundata (bitou bush)

P>Seed longevity has a major influence on the success of weed management and eradication programmes. A correlation between responses to a controlled aging test performed at 45 degrees C, 60% relative humidity (RH) and seed persistence in the field has recently been suggested. Here we investigated whether collections of differing quality of two closely related invasive weeds, Chrysanthemoides monilifera ssp. monilifera and ssp. rotundata (boneseed and bitou bush, respectively), had different seed longevity using the controlled aging test. Chrysanthemoides monilifera ssp. monilifera fruits were collected from across five Australian states, and C. monilifera ssp. rotundata from one state, covering their invasive ranges. Seed quality was assessed visually and using tetrazolium staining, and a series of germination tests established appropriate germination conditions. The controlled aging test was run for a subset of collections. Chrysanthemoides monilifera ssp. rotundata seeds died more quickly (time to lose 50% viability, P(50) = 16 days) than the C. monilifera ssp. monilifera collections (P(50) = 47 days) when aged at 45 degrees C and 60% RH. This difference was significant even considering the large differences in longevity between C. monilifera ssp. monilifera populations (P(50) = 35-61 days; probably due to differences in maturity at collection). Based on a published correlation, we predict that mature C. monilifera ssp. monilifera may have a long-lived (> 3 years) seed bank and C. monilifera ssp. rotundata may have a transient (< 1 year) seed bank. This suggests the two sub-species should be considered separately when designing effective control measures