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Block Reference: #89bdb1e9-72b3-11ec-990b-6e775a745849
Date and time: Tue, 11 Jan 2022 07:53:17 GMT
2. Often this trigger is a seasonally related stimulus which can switch on germination at an adaptively appropriate time of year
In this unit we will learn the established model of seed germination and dormancy. We will also discuss how a better model might be developed. Warning signs that you are headed in the wrong direction in your thinking can be signaled by the following terms, often used. BEWARE!:
2. Dormancy caused by mechanical restriction of growth by embryo coverings (pericarp, testa, perisperm, endosperm)
-example: cocklebur: upper seed (of two in capsule) radicle is restricted, insufficient thrust to rupture testa and germinate
Somatic polymorphism: Production of seeds of different morphologies or behavior (phenotypes) on different parts of the same plant; not a genetic segregation but a somatic differentiation
CO2 narcosis: example: Brassica alba dormancy induced by high CO2 treatment
Physical restriction of gas exchange and growth
Evolutionary and environmental context of weed seed dormancy as an adaptive strategy in the struggle for existence
In this unit we will learn about seed dormancy as seen by many respected seed biologists, the way most scientists in the seed discipline view this complex area of plant biology. The concepts and organization of this unit follow this traditional way of looking at seed dormancy. It is essential that you understand these concepts, and see them from this perspective, if you are to have an understanding of weed seed biology and the scientific literature on seed dormancy.