Intraseminal fungal location in maize of selected seed storage fungi in relation to some physiological parameters

Maize seeds that had been hot-water-treated (30min at 55°C) to reduce inherent infection, were inoculated with the spores of four storage fungal species of varying xerotolerance. The less xerotolerant species (Aspergillus oryzae and Aspergillus sydowi) were characterized by vigorous growth on the six single carbon source media tested, and were also associated with rapid and extensive degradation of all the seed tissues. The more xerotolerant species (Aspergillus chevalieri and Penicillium pinophilum), on the other hand, grew only slowly in vitro and were not located in the embryo despite six weeks storage of the artificially infected seeds at 95% relative humidity. Germinability of infected seeds decreased with storage time, as did the dry mass of the resultant seedlings, the extent of the decline increasing with decreasing xerotolerance of the fungal species. The rate of infection of, and ultimate mycelial location in, the seeds are suggested to be related to the extracellular enzyme capabilities of the individual species

Seed storage and germination in Kumara plicatilis, a tree aloe endemic to mountain fynbos in the Boland, south-western Cape, South Africa

AbstractSeed storage under appropriate conditions is a relatively inexpensive means of safeguarding plant genetic material for ex situ conservation. Post-storage germination trials are used to determine the viability of stored seeds, and hence the efficacy of the particular storage treatment. Kumara plicatilis (=Aloe plicatilis) is a tree aloe endemic to mountain fynbos in the Boland, south-western Cape. The viability and germination behaviour of K. plicatilis seeds were assessed for seeds stored for four and nine months at −80°C, 4°C, 25°C and under ambient conditions in a laboratory. Seeds were germinated under controlled conditions and germination rates and percentages determined. Ungerminated seeds were tested for viability using tetrazolium salt. Seed viability was not significantly reduced during storage. Seeds stored at −80°C for four and nine months exhibited the fastest germination rate overall (both 5.9±0.3 weeks, mean±S.E.), and slowest was for seeds stored under ambient conditions for four and nine months (both 7.8±0.4 weeks). All seed lots showed similar percentage germination after four months of storage (78.0–90.4%). The highest percentage germination overall was for seeds stored at −80°C for four months (90.4%) and the lowest was for seeds kept at 4°C and −80°C for nine months (39.2 and 39.6%, respectively). Respective percentage viability for ungerminated seeds in these two treatments was 82% and 87%, respectively, indicating the induction of secondary dormancy. Induced dormancy triggered by protracted cold temperatures may be an adaptation that enables seeds to survive prolonged extreme conditions that are unfavourable for germination. Further research on the long-term storage of aloe seeds would be beneficial for developing long-term seed storage and germination testing protocols for ex situ conservation