Day length and crop yields
By: [by M.W. Parker and H.A. Borthwick].
Contributors: Borthwick, H. A. 1898-
Series: Miscellaneous publication / United States Department of Agriculture -- no. 507; Miscellaneous publication (United States. Dept. of Agriculture) -- no. 507.
Publisher: U.S. Dept. of Agriculture
Published: 1942
Place of publication: Washington, D.C
Language: eng
Number of pages: 22
Subjects: Plants -- Effect of light on.; Crop yields.; Plant photoperiodism.
Notes: Cover title.

"Issued September 1942."