Agriculture Reference
In-Depth Information
other Species
Other species, even unfamiliar ones, may be tested by following instructions in the most current AOSA and
ISTA tetrazolium testing handbooks. However, unfamiliar species may also be tested by gaining a good
knowledge of both internal and external seed anatomy and morphology and how these relate to tetrazolium
techniques.
Flower seeds represent one of the most variable groups of seeds in terms of size, shape and both internal
and external morphology. Although most analysts may be unfamiliar with many lower seeds, some labora-
tories specialize in TZ testing of lower seeds and other lesser known species. Good results can be obtained
for such species by developing a sound knowledge of seed structure and morphology, especially that of the
embryo and how it relates to the endosperm and seed coat. Ransom Atwater (1979) listed eight embryo
groups previously cited by Bailey and Bailey (1976) found in different lower species as follows:
1. Seeds with a dominant endosperm and immature dependent embryo.
a. Basal rudimentary embryo (e.g., Anemone coronaria )
b. Axillary linear embryo (e.g., Primula eximia )
c. Axillary miniature embryo (e.g., Scrophularia californica )
d. Peripheral linear embryo (e.g., Portulaca grandilora )
2. Seeds with residual or no endosperm and mature independent embryo.
a. Hard seed coat, limiting water entry (e.g., Ipomoea purpurea )
b. Thin seed coat with mucilaginous layer (e.g., Iberis amara )
c. Woody seed coat with inner semi-permeable layer (e.g., Verbena x hybrida )
d. Fibrous seed coat with separate semi-permeable membranous coat (e.g., Helianthus annuus )
Procedures for each type of species are given below.
 
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