Abstract
Plant growth and development affected by variations in light and dark periods generally have been studied under periodic alternation of light and dark periods (P) . In other words, few studies have been conducted under non-periodic alternation of light and dark periods (N) . We classified N into six types according to characteristics of light and dark periods. In the present study, NA (one of six types) was used as the experimental condition. The growth and development of tomato seedlings under two NA treatments (NA-1 and NA-2) were compared with those under a P treatment (light/dark periods : 12 h/ 12 h) . Under NA treatments, one of 28 integers randomly generated in the range of 2 to 22 was allotted to each of light and dark periods, being resulting in each of integrated light and dark periods approximately 168 h. The results showed that fresh mass and leaf area were on the order of NA-2>P>NA-1; dry mass was on the order of P> NA-1 NA-2; and stem length was on the order of NA-2>NA-1>P. While, the number of differentiated leaves before the differentiation of the first flower truss was not significantly different for all treatments. In short, the growth of tomato seedlings under the non-periodic alternation of light and dark periods was different from that under the periodic alternation of light and dark periods, while their development was similar to each other.
