Rooting, root growth and root morphology of two Karwinskia species in vivo and in vitro

Differences in root morphology of Karwinskia humboldtiana and Karwinskia parvifolia seedlings cultivated in greenhouse were analyzed every three weeks up to the age of five months, and then in the age of seven months. The increase in total root length and number of lateral roots of all orders was significantly higher for K. humboldtiana. Branching pattern of roots in K. humboldtiana was irregular, but in the majority of plants lateral roots were developed along the whole axis of the main root. In K. parvifolia the most intensive branching occurred on the base of the main root. Rooting of stem cuttings in vivo was low and occurred only after application of growth regulators - auxinoids. Inter-species variation in the effect of these compounds was observed. Differences in rooting of shoots (on WPM medium supplemented with NAA) and root morphology were observed also under in vitro conditions. In K. humboldtiana the development of adventitious roots on isolated shoots started earlier and the percentage of rooted shoots was higher than in K. parvifolia. The formation of lateral roots in vitro was observed only in K. humboldtiana.