Improving the identification, handling and storage of “difficult” seeds ...

4. RBG Kew species analysis
Improving the identification, handling and storage of “difficult” seeds:
Species Analysis
Ms. Vanessa Bertenshaw
Royal Botanic Gardens, Kew
Abstract
In order to get some idea of the extent to which “difficult” species cause problems for gene banks,
we analyzed several databases to produce a combined list of 768 species. 80% of these species
produced desiccation-tolerant (‘orthodox’) seeds. A further 15% are probably orthodox but may
need further investigation. Only 5% are definitely or likely desiccation-intolerant (‘recalcitrant’)
species. Several species from the Poaceae family present difficulties due to dormancy. Relative
longevity values for 39 ITPGRFA Annexe 1 species are presented.
What do we mean by “difficult” seeds?
▪ Inherently difficult
- recalcitrant or intermediate seeds
- orthodox but dormant
- orthodox but short-lived
▪ “Difficult” due to poor handling/storage
- immature orthodox seeds dried too rapidly
- orthodox seeds insufficiently dried prior to storage and/or stored under poor conditions
- Seeds that have been damaged by insects (on-farm storage)
The purpose of the study was to highlight species that were truly difficult because of storage
behaviour, germination requirements or inherently short storage potential, and distinguish them
from species which are “difficult” because they have been poorly handled.
Data sets analysed for “difficult” species
▪ Species listed in Annexe 1 of the ITPGRFA (www.fao.org/ag/cgrfa)
▪ Tropical Forages list (www.tropicalforages.info)
▪ A list of underutilized species (Padulosi, 1998)
▪ A list of leafy vegetables (Sheela et al, 2004)
▪ Groundnuts, onions and tomatoes stored by CENARGEN at Embrapa genebank
(www.cenargen.embrapa.br)
The combined species list represents 768 species from a total of 97 families. The families with the
highest numbers of species included in the study are shown in Table 1. Of note are the
Leguminosae-Papilionoideae and Poaceae families with 210 and 143 species, respectively, in the
list.