Viability of Seeds
From prehistoric times man has had a pecial s relationship with seed plants - as a source of food, materials for tools, buildings, clothing and pharmaceuticals, and for ornamenting his surroundings for his own delight (probably in that chronological order
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		    A
 
 B
 
 c
 
 1
 
 2
 
 3
 
 Mutant phenotypes produced from aged seeds (see Chapter 9, pp. 2.61- 3). Peas (Pisum
 
 salitlllm) : lA, Yellowish-edges; 18, Maculala; Ie, Xantha. Broad beans ( Vida jabal:
 
 211., Greenish-yellow; 2B, Maculata; lC, Xamha; 3" Chlorina. Barley (Hordeum vulgare) : 3B, Albino; 3C, Striata. All photographs (except I B and 28) indude examples of the normal phenotypes for comparison.
 
 Viability of Seeds
 
 Edited by
 
 E. H . Roberts Pro/essor of Crop Production. Department 0/ Agriculture, University of Reading
 
 C HAPMAN AND HALL LTD II NEW FETTER LANE · LONDON EC4
 
 First published 1972 Reprinted 1974 ISBN-I3: 978-94-009-5687-2 001: 10.1007/978-94-009-5685-8
 
 e-ISBN-13: 978-94-009-5685-8
 
 © 1972 Chapman and Hall Ltd Photoset by BAS Printers Limited, Wallop, Hampshire and Softcover reprint of the hardcover 1st edition 1972
 
 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher.
 
 Contents
 
 Contributors Preface
 
 page vii VlIl
 
 CHAPTER I
 
 Introduction E. H. Roberts
 
 I
 
 CHAPTER 2
 
 Storage environment and the comrol of viability E. H. Roberts 3 Microftora and seed deterioration C. M. Christensen
 
 14
 
 CHAPTER
 
 59
 
 CHAPTER 4
 
 Effects of mechanical injuries on viability R. P. Moore
 
 94
 
 CHAP T ER 5
 
 Effects of environment before harvesting on viability R. 8. Austin
 
 114
 
 CHAPTER 6
 
 Effects of environment after sowing on viability Bruce M. Pollock
 
 150
 
 CHAPTER 7
 
 The measurement of viability D. B. MacKay CHAPTER
 
 172
 
 8
 
 Vigour W. Heydecker
 
 20I} is used for the half·viability period and p for the mean viability period. As discussed earlier. under most circumstances the distribution of the viability periods amongst the individual seeds of a population is normal and therefore symmetrical, in which case Pf>I} and p are identical. There are some advantages, however, in retaining the distinction and being d ear as to which measure of viability is' adopted for particular circumstances.
 
 Storage Environment and the Control of Viability
 
 21
 
 [Q apply [Q rice which was investigated over the range 12-14.5 per cent moisture content and 27-47°C, although the values of the constants were different from wheat. Further experiments on barley (H ordeum distichon), broad beans (Vicia/aba ), and peas (Pisum sativum) over [he ranges 25-45°C and 12-18 per cent moisture content showed that equation (2.5) provided an excellent fit in all cases, although the constants are slightly different for the three species (Roberts and Abdalla, 1968). An equation based on the relationship expressed by equation (2-4) was also tested. It will be seen that this relationship could be written in terms of equation (2.5 ) as:
 
 log PIOO
 
 =
 
 (2.6)
 
 Kv
 
 although since the end-point (PIOO) is different and since the moisturecontent constant refers to a log value, the values of the constants K v and C1 would be different. The essential difference between the		
 
	 
	 
	 
	 
	 
	 
	 
	 
	 
	 
	