Effect of IBA and Caffeic Acid on Rooting of Black Mulberry (Morus nigra L.) Hardwood Cuttings in Different Dark Conditions

Research was carried out in an experimental greenhouse on the lands of Agricultural Applications and Research Center in Tokat Gaziosmanpasa University in 2021. In the study, the effects of 6000 ppm indole-3-butyric acid (IBA) and 2000 ppm caffeic acid (CA) applications on the rooting of black mulberry hardwood cuttings under different dark conditions were investigated. The experiment was set up in a factorial pattern with 3 replications according to the randomized plot design. As plant material, one-year-old hardwood cuttings of black mulberry taken from trees grown in Agricultural Applications and Research Center were used. Hardwood cuttings were collected on February 2021 and then planted in bottom-heated (20 +/- 2 degrees C) perlite medium. The cuttings were divided into 3 groups and the cuttings in the first group were covered with black mulch after planting (Dark After Planting=DAP); the cuttings in the second group were kept in the dark for 5 days before planting and then planted in the rooting medium (Dark Before Planting=DBP); no dark was applied to the cuttings in the third group (Standard). 6000 ppm IBA and 2000 ppm CA, either alone or together, were applied to the cuttings in each dark treatment. The hardwood cuttings were kept in the rooting environment for 90 days and at the end of this period each cuttings were scored for rooting rate, callus formation rate, decay rate, root number, root length, and root diameter. As a result of the study the rooting rate varied between 2.2% and 77.8%. The highest rooting rate was achieved from 6000 ppm IBA and 6000 ppm IBA+2000 ppm CA applications to the cuttings in the DBP conditions. The rate of callus-forming cuttings varied between 64.4% and 93.3%, root number varied between 1.5 and 14.4 per cuttings, root length varied between 3.6 and 10.8 cm, and root diameter varied between 0.86 and 1.53 mm. The data showed that the application of IBA either alone or together with CA to the cuttings kept in the DBP condition had a positive effect on the rooting of the black mulberry hardwood cuttings.