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An analysis of major U.S. crops shows that there is a large genetic potential for yield that is unrealized because of the need for better adaptation of the plants to the environments in which they are grown. Evidence from native populations suggests that high productivity can occur in these environments and that opportunities for improving production in(More)
All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Companion to: Water relations of plants and soils / Paul J. Includes bibliographical(More)
In many situations, organisms respond to stimuli by altering the activity of large numbers of genes. Among these, certain ones are likely to control the phenotype while others play a secondary role or are passively altered without directly affecting the phenotype. Identifying the controlling genes has proven difficult. However, in a few instances, it has(More)
Pectin is a normal constituent of cell walls of green plants. When supplied externally to live cells or walls isolated from the large-celled green alga Chara corallina, pectin removes calcium from load-bearing cross-links in the wall, loosening the structure and allowing it to deform more rapidly under the action of turgor pressure. New Ca(2+) enters the(More)
The effects of cations and abscisic acid on chloroplast activity in guard cells of Vicia faba were investigated by analysis of the transient of chlorophyll a fluorescence. When epidermal strips containing guard cells as the only living cells were incubated in water and illuminated with strong light, chlorophyll a fluorescence rose rapidly to a high(More)
(1) Photophosphorylation, Ca2+-ATPase and Mg2+-ATPase activities of isolated chloroplasts were inhibited 55--65% when the chemical potential of water was decreased by dehydrating leaves to water potentials (psi w) of --25 bars before isolation of the plastids. The inhibition could be reversed in vivo by rehydrating the leaves. (2) These losses in activity(More)
Water vapor over-estimates the CO 2 entering leaves during photosynthesis because the cuticle and epidermis transmit more water vapor than CO 2 . Direct measurements of internal CO 2 concentrations may be preferred. The CO2 concentration inside leaves (c i) is typically calculated from the relationship between water vapor diffusing out while CO2 diffuses(More)