Kathryn Keeley’s research while affiliated with The Ohio State University and other places

More than 3,000 Norton hardwood cuttings were tested in an experiment conducted under commercial greenhouse propagation conditions. Treatment with 10,000 or 15,000 mg/L potassium salt of indolebutyric acid (KIBA) caused >70% of the cuttings to root, compared with 23% rooting of the nontreated control cuttings. In studies at a university greenhouse under intermittent mist, cuttings that were collected in January and stored in a cooler at 5 degreesC for greater than or equal to55 days (>2300 hours of natural plus cooler chilling) formed more roots than cuttings receiving fewer hours of chilling. Cuttings in this experiment that were treated with 15,000 mg/L KIBA formed significantly more roots than cuttings not treated with auxin. Hardwood cuttings and softwood cuttings taken from more basal or middle cane segments rooted better than cuttings from nearer the apical region. Softwood cuttings formed more roots when treated with 2,500 mg/L KIBA compared to the nontreated control cuttings.

Hardwood and softwood cuttings of Vitis aestivalis Michx. 'Nortan' were rooted under intermittent mist in a series of experiments using cuttings collected from two local vineyards. Hardwood, cuttings treated in late March responded in a similar manner to KIBA and KNAA. Although there was little increase in the percentage rooting above 22.29 mm KIBA or 20.72 mm KNAA (5000 mg(.)L(-1) of either auxin), root number (but not root length) increased linearly on cuttings treated with up to 44.58 mm KIBA or 41.44 mm KNAA (10000 mg(.)L(-1) auxin). Cuttings treated with 10000 mg(.)L(-1) auxin produced up to 4 times more roots than the nontreated controls. The gibberellin biosynthesis inhibitors CCC and PAC had little effect on either hardwood cuttings or softwood cuttings that were harvested, treated and placed in the propagation bench in June. However, when softwood cuttings Were collected in August, the most roots were found on cuttings treated with 50.6 mm CCC or 0.85 mum PAC. Although all hardwood cuttings were collected at the same time and stored under refrigerated conditions, rooting percentage increased as storage time increased, especially on the nontreated control cuttings. When the cuttings were stored for the longest time (six weeks), KIBA no longer caused more roots per cutting. Chemical names used: potassium salt of indole-3-butyric acid (KIBA), potassium salt of alpha-naphthaleneacetic acid (KNAA), chlormequat chloride (CCC), paclobutrazol (PAC).

Hard-to-root hardwood cuttings of Vitis aestivalis `Norton' were collected during Feb. 1999. Cuttings had three nodes and were 10 to 15 cm long. Prior to treatments, cuttings were submersed in a solution of 9.5 g/1L of ZeroTol (a mixture of hydrogen dioxide and peroxyacetic acid). The bottom two nodes were placed into 1 vermiculite: 1 perlite (by volume) and set under mist in the greenhouse at of 20/15 °C day/night). About 5 weeks after treatment, number of roots and root length data were collected. The bottom 2 cm of cuttings in one experiment received a 30-s dip in 0, 2500, 5000, 7500, or 10,000 mg/L IBA and/or NAA to determine the effects of these treatments on rooting of hardwood cuttings. IBA and NAA are not significantly different, however there was a positive linear relationship between rooting and concentration of auxin. As concentration of auxin increased, mean number of roots increased. In additional experiments, cuttings treated with 0 or 5000 mg/L of IBA were compared based on timing after harvest of cuttings and treatment. Of the cuttings treated and placed under mist on 26 Mar. 1999, 30% of the control cuttings rooted and 50% of the cuttings treated with 5000 mg/L rooted. Two weeks later, 65% and 55% of the cuttings treated with 5000 mg/L rooted respective to the 0- and 5000-mg/L treatments. One week later (14 Apr. 1999), 77.5% and 72.5%, respectively, rooted. This suggests that timing after harvest for placing the cuttings in a propagation bed is important for increasing the rooting percentage of `Norton' hardwood cuttings.