Some Effects of Temperature and Photoperiod on the Growth of Tomato Seedlings

Abstract

1. Tomato seedlings of the variety San Jose Canner, otherwise maintained at 14⚬ C., were subjected to temperature treatments at 3⚬ and 30⚬ C. in the light or in the dark. Such treatments from 1 to 20 hours out of 24 and various photoperiods were employed for 4-5 weeks. 2. Both heat and cold treatments in the dark resulted in lower dry-weight production. Short treatments produced severe growth limitations. This effect could have important agricultural implications. The effects are proportionally the same at all photoperiods from 4 to 20 hours. 3. Treatments at 30⚬ C. in the light limited growth less than in the dark, and the growth decrease is linear with the length of treatment time. 4. High-temperature treatment in the light resulted in greater height, but in the dark, in lesser height. Cold-temperature treatment in light or dark depressed height growth. 5. When both high- and low-temperature treatments were given in the dark to the same plants, the order of the treatments and the part of the night durin...