In vitro plantlet development from explants of 25-year-old trees of Populus × euramericana — a hybrid poplar

Abstract

The nodal and internodal segments of young branches of 25-year-old of Populus × euramericana, differentiated adventitious multiple shoots within 3 weeks of inoculation on Murashige and Skoog's (MS) medium. They developed directly (i) at cut ends in both explants, (ii) in lenticel regions of internodes and (iii) in axils of leaves on nodal portions. The maximum frequency of in vitro organised shoots forming roots was 44% on MS + 10.7 μM α-naphthaleneacetic acid + 0.75% activated charcoal within 15 days of subculture. The rooting response was enhanced to 79% by subculturing shoots on the same medium in 100 ml conical flasks instead of 15 × 2.5 cm test tubes. Glutamic acid, 100 mg/l, added to the rooting medium, effectively controlled yellowing of leaves and their abscission in tissue culture-raised plantlets. These plantlets have now been successfully transferred to soil. Thus, 5–15 plantlets can be produced from each internodal explant within 60 days, of a hybrid poplar which does not flower and consequently bears no seeds in Delhi.