. Day length and crop yields. Plants; Crop yields; Plant photoperiodism. has been critically investigated. It lias been learned that many kinds of plants are much more sensitive to photoperiodic conditions when grown at certain temperatures than at others. Some varieties become more sensitive after they have been subjected to certain tem- peratures for various periods of time. Such exposure is often referred to as preconditioning. This relation to temperature is of great eco- nomic importance, as shown by peach and apricot trees, which leaf out very slowly in the spring or shed their flower bu
. Day length and crop yields. Plants; Crop yields; Plant photoperiodism. has been critically investigated. It lias been learned that many kinds of plants are much more sensitive to photoperiodic conditions when grown at certain temperatures than at others. Some varieties become more sensitive after they have been subjected to certain tem- peratures for various periods of time. Such exposure is often referred to as preconditioning. This relation to temperature is of great eco- nomic importance, as shown by peach and apricot trees, which leaf out very slowly in the spring or shed their flower buds prematurely unless they have experienced a certain number of hours or days of relatively low temperature during the winter or early spring. Many bulbous plants, some grains, and various other crops grow more vigorously after they have been subjected for a time to low tem- peratures. Plants may be pre- conditioned during the seed stage, during periods of relative dormancy, or while they are in active growth. Preconditioning may occur naturally in northern latitudes at certain times of the year, or it may be provided readily wherever facilities for cold storage are available. The photoperiodic conditions of a region are the most nearly constant recurrent environ- mental factors to which plants are subjected. The photoperiod and the temperature which pre- Some onion varieties when grown where the photoperiod is long produce and mature bulbs, but they fail to form bulbs when grown where the photoperiod is Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Parker, M. W. (Marion Wesley), 1907-; Borthwick, H. A. (Harry Alfred), 1898-. Washington, D. C. : U. S. Dept. of Agriculture
Size: 1058px × 2362px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublisherwashingtondcusd, booksubjectplants
