Effects of Cotyledon Excision on the Flowering of Five Varieties of Pisum sativum

Abstract

The cotyledons were excised from seedlings 4 days after planting, and the effects of the treatment on plants grown under a 16-hour photoperiod, a 20[degree]C phototemperature, and a 17 [degree]C nyctotemperature were noted. The treatment lowered the position of the 1st flower by 2-3 nodes in the 2 late varieties Dwarf Telephone and Unica, but was without effect on the Tall Telephone variety. The number of nodes to the 1st flower was increased by 1-2 in the early varieties Massey and Alaska. Height to the 1st flowering node was reduced from 24 to 48% in the decotylized plants, depending on the variety. Anthesis was delayed 3 weeks in decotylized Alaska peas and 2 weeks in decotylized plants of the other 4 varieties. Further studies showed that the effects of cotyledon excision on flowering varied quantitatively with light intensity. The number of nodes to the 1st flower was found to be directly proportional to light intensity in control and decotylized plants of 2 late varieties and in decotylized plants of an early variety.