Evaluation of aeroponics for clonal propagation of Caralluma edulis, Leptadenia reticulata and Tylophora indica - three threatened medicinal Asclepiads.

The present study explores the potential of aeroponic system for clonal propagation of Caralluma edulis (Paimpa) a rare, threatened and endemic edible species, Leptadenia reticulata (Jeewanti), a threatened liana used as promoter of health and Tylophora indica (Burm.f.) Merill, a valuable medicinal climber. Experiments were conducted to asses the effect of exogenous auxin (naphthalene acetic acid, indole-3-butyric acid, indole-3-acetic acid) and auxin concentrations (0.0, 0.5, 1, 2, 3, 4 or 5gl(-1)) on various root morphological traits of cuttings in the aeroponic chamber. Amongst all the auxins tested, significant effects on the length, number and percentage of rooting was observed in IBA treated nodal cuttings. Cent per cent of the stem cuttings of C. edulis rooted if pre-treated with 2.0 gl(-1) of IBA for 5 min while 97.7 % of the stem cuttings of L. reticulata and 93.33 % of stem cuttings of Tylophora indica rooted with pre-treatment of 3.0 gl(-1) of IBA for 5 min. Presence of at least two leaves on the nodal cuttings of L. reticulata and T. indica was found to be a prerequisite for root induction. In all the species, the number of adventitious roots per cutting and the percentage of cuttings rooted aeroponically were significantly higher than the soil grown stem cuttings. Shoot growth measured in terms of shoot length was significantly higher in cuttings rooted aeroponically as compared to the cuttings rooted under soil conditions. All the plants sprouted and rooted aeroponically survived on transfer to soil. This is the first report of clonal propagation in an aeroponic system for these plants. This study suggests aeroponics as an economic method for rapid root induction and clonal propagation of these three endangered and medicinally important plants which require focused efforts on conservation and sustainable utilization.