Abstract
In breeding pea (Pisum sativum L.) with short stature, a rapid method of selecting progenies with short internodes is desirable. Insofar as parentage, light quality and light intensity affect internode lengths, pea cultivars of varying internode lengths derived from seeds, ovules and plumules grown in vitro were compared with those grown in the greenhouse. 1. Pea cultivars with diminishing internode lengths under greenhouse culture were : 'Yatawaseusui', 'Kishu-usui', 'Oranda', 'Misasa', 'Kishu-saya 2' and 'Tiny Peace'. 2. Varietal differences in stem internode lengths of plants which were derived from seed, ovule (pod) and plumule grown in vitro corresponded to those grown in the greenhouse. Hence, internode lengths of cultivars could be evaluated in vitro during their period of accelerated growth. 3. The varietal difference in stem internode lengths of shoots regenerated from callus was less than that derived from plumules. 4. The longest internode length of pea cultivars grown in vitro was about twice that of the mean. Furthermore, cultivars with the shortest internodes also had the shortest mean length. Hence, internode length of progenies grown in vitro may offer a good index for selecting plants of short stature. 5. The varietal differences in internode lengths of plants grown in vitro under white lights became even larger under yellow fluorescent lights. 6. The internode lengths of cultivars grew proportionately longer at 100-500 lx than at 3, 000 lx.
