Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Seed Coat Effects
In some seeds dormancy is imposed by the presence of the seed coat; if this is removed, the seed germinates. Two possible types of mechanisms could be involved, one biochemical or physiological and the other purely mechanical.
Scarification
The seed coat is nearly impervious to the diffusion of gases. Wareing's group found that seeds of Birch (Betula Pubescens), which would not germinate intact, would do so if the seed coat were scratched or broken. Moreover, added oxygen greatly stimulated germination of such damaged seeds. Evidently the embryos themselves were not dormant; they would germinate if isolated from the seed An alternative possibility is that the seed coat might prevent the leaching out of a diffusible inhibitor. The second, or mechanical alternative has been investigated by Y. Esashi and A.C. Leopold using seeds of Xanthium pennsylvanicum (also called Xanthium strumarium), the cocklebur.
This plant produces two kinds of seeds in each fruit large, non dormant ones and small, dormant ones. The investigators used the specially designed apparatus to show that neither type of seed generates enough force to rupture the testa during imbibitions. During growth, however, the large, non dormant seeds generate sufficient force to break it whereas the smaller dormant seeds do not. This shows, for Xanthium at least, that the long held opinion that the embryo must generate sufficient force during germination to rupture the seed coat is correct. Moreover, it is clear that the forces generated by imbibitions alone are not sufficient. Active growth is also needed.
what are the character selection criteria?
the function of contractil vacuole
If you have a control group for your experience, which of the following statements is true? A. The control group should be identical to each test group with the exception of one va
Q. What are the events that mark the beginning and the end of the third interphase period? What happens in the cell in this period? The third interphase period is the G2, It be
Describe the result of Pulmonary Embolism? Results : The mortality in different series is reported between 3 and 36 per cent. In haemodynamically unstable patients this coul
Explain functional properties of gellan gums One of the most important features of gellan gums is its versatile texture which is defined in terms of hardness (measure of ruptur
is crossing over of chromosomes is a method?
A friend of yours suggests that the origin of life on earth is extraterrestrial in origin (an idea known as panspermia). Can you propose a testable hypothesis to determine if this
#qwhy is it necessary to grind the foo sample before testing uestion..
Illustrate the types of Bone Remodeling Bone remodeling occurs on existing bone surfaces. However, unlike modeling, remodeling cannot cause large changes in bone structure at a
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd