HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Keisling, T. C. Search for Related Content PubMed Articles by Keisling, T. C. Agricola Articles by Keisling, T. C.

Calculation of the Length of Day¹

With the advent of sophisticated computing capability many tables and curves that were standard methods of obtaining values in the past can be computed directly with the appropriate formulas. The photosensitivity of many agronomic crops makes knowing the length of hours that the light intensity is above a certain critical level useful. A formula for calculating daylength is presented and methods indicated for obtaining the desired beginning and ending light intensity at any location. The only information necessary to utilize the formula is the latitude of the location and the critical light intensity of interest for the particular crop being used.

Key Words: Photoperiod • Daylength • Flowering • Flower induction

² Associate professor, Dep. of Agronomy, and Extension Agronomist&Soybeans, Univ. of Arkansas, located at P. O. Box 391, Little Rock, AR 72203.

Received for publication August 17, 1981.

This article has been cited by other articles:

				B. Clerget, M. Dingkuhn, E. Goze, H. F. W. Rattunde, and B. Ney Variability of Phyllochron, Plastochron and Rate of Increase in Height in Photoperiod-sensitive Sorghum Varieties Ann. Bot., March 1, 2008; 101(4): 579 - 594. [Abstract] [Full Text] [PDF]

				N. A. STRECK, A. WEISS, Q. XUE, and P. S. BAENZIGER Incorporating a Chronology Response into the Prediction of Leaf Appearance Rate in Winter Wheat Ann. Bot., August 1, 2003; 92(2): 181 - 190. [Abstract] [Full Text] [PDF]