In vitro Polyploidization of Zehneria capillacea (Shumach.) C. Jeffrey Using Nodal Explants

Zehneria capillacea (Schumach.) C. Jeffrey is a wild diploid (2n = 2x = 22) andromonoecious climber that is eaten as vegetable in Nigeria. In vitro polyploidy induction was conducted using oryzalin as a microtubule inhibitor at various concentrations (10, 20 and 30 µM) and two time durations (24 and 48hrs). This research was conducted to develop a protocol for induction of polyploids through in vitro technique in order to create variability and broaden the genetic base of this species. Shoot length was significantly affected by oryzalin concentration at 24 and 48 hours treatment duration. The nodal segments immersed in 10, 20 and 30 µM oryzalin for 24 hrs had shoot lengths of 7.56 ± 0.06 cm, 7.24 ± 0.06 cm and 7.31 ± 0.07 cm respectively which were statistically similar while the shoot length of those treated for 48 hrs significantly decreased with increase in oryzalin concentration ranging from 7.02 ± 0.07 cm for 10 µM to 2.71 ± 0.11 cm for 30 µM. 10 µM oryzalin for 24 hrs and 48 hrs induced 100% 2x+4x and 2x+4x+8x cytochimera respectively. Application of 20 µM for 24 hrs induced 75% 2x+4x and 25% solid tetraploids while 20 µM for 48 hrs induced 25% 2x+4x and 75% solid tetraploids. Application of 30 µM oryzalin for 24 hrs induced 100% 2x+4x+8x and 48 hrs induced 20% 2x+4x+8x and 80% 4x+8x. The results obtained indicate that polyploids (tetraploid, 4x and octoploids, 8x) can be induced using nodal explants from Z. capillacea grown in vitro thereby conserving and enhancing the ethno-botanical and economic values the species.