Effect of Light Periods and Temperatures on Plant Form of Nicotiana tabacum L. cv. Hicks

Abstract

Light/dark temperatures of 30/30, 30/15, 15/30, and 15/15 C resulted in four plant forms of Nicotiana tabacum L. cv. Hicks in both 9 and 15 hr of high-intensity light. Plants in the 30/30 C temperatures were similarly tall in both light periods with many leaves (38.5; 34.7) which were correspondingly large but more ovate in the 15 hr of light. Plants in the 15/15 C temperatures were similarly very spindly in form with reduced numbers of leaves (19.0; 24.5), each with a prominent petiole and very acute leaf tip. The characteristics were more extreme in an acropetal direction with the upper leaves being very lanceolate. Plants in the 30/15 and 15/30 C temperatures were intermediate in form, with the exception of those in 15/30 C and 9 hr of light. These plants were relatively short but had 38.7 leaves that were yellowish green in color. It required 117 days for flowering in plants receiving 9 hr of light and only 92 in plants receiving 15 at the 15/30 C temperatures. Results indicate that night temperature ...