Leaf Heteromorphism and Photoperiods in Sesamum Orientale L

Abstract

IN connexion with an investigation on the photoperiodic effect in Sesamum orientale L. (I.P. 7 and I.P. 29) in relation to the variations of the environmental factors of the four seasons: winter (sown on January 1), summer (sown on April 1), monsoon (sown on July 4) and autumn (sown on October 1), it was found that the leaf-forms in both the varieties were extremely variable. The lower leaves are generally ovate lanceolate, and with the onset of flower buds linear lanceolate leaves were produced in addition to a large number of leaves of different shapes with serration and various degrees of split margins depending upon the sowing time and different photoperiods. The variation of leaves was a prominent feature in plants growing in long photoperiods (14 hr.), but was not observed in plants growing in short photoperiods (10 hr.). The control plants of the monsoon sowing exposed to the long photo-periods of Nature (13 hr. 9 min. to 11 hr. 55 min.) also showed clear variations.