Plant growth regulator optimization for improved rooting efficiency in golden kiwifruit (Actinidia chinensis Planch.)

Abstract

The advancement of the kiwifruit industry in South Africa (SA), necessitates the development of other kiwifruit cultivars to supplement the Actinidia deliciosa kiwifruit. However, rooting difficulties are often experienced without the use of plant growth regulators. The effect of Indole-3-butyric acid (IBA) alone and in combination with Naphthalene acetic acid (NAA) on rooting Actinidia chinensis stem cuttings was investigated. The study was conducted at Politsi Nursery, Tzaneen, Limpopo province of SA in 2021-22, mainly during winter months (May-August) for 120 days. In experiment 1, semi-hardwood stem cuttings were treated with 0 (control), 2500, 5000, 7500 and 10000 ppm IBA. In experiment 2, treatments comprised a combination of various IBA and a constant concentration of NAA, namely, 0 + 0 (control), 2500 + 1000, 5000 + 1000, 7500 + 1000 and 10000 + 1000 ppm, respectively. In experiment 1, the highest (90%) rooting percentage, highest dry root mass (0.45 g) and the longest (7.25 cm) root were obtained at 5000 ppm IBA. In experiment 2, the highest (80%) rooting percentage and number of roots (9.06) were observed at 7500 IBA + 1000 NAA ppm. In conclusion, the use of IBA alone proved its suitability for enhancing rooting percentage, dry root mass and longer root formation compared to IBA in combination with NAA.