N‐phenyl indolyl‐3‐biityraitiide and phenyl indole‐3‐thiolobutyrate enhance adventitious root primordium development

Abstract

N‐phenyl indoryl‐3‐butyramide (NP‐IBA) and phenyl indole‐3‐thiolobutyrate (P‐ITB) are new synthetic auxins that enhance rooting of bean (Phaseolus vulgaris cv. Top Crop) hypocotyl cuttings and jack pine (Pinus banksiana Lamb.) seedling cuttings. In comparison with an equal concentration of indole‐3‐butyric acid (IBA), NP‐IBA treatment resulted in greater rooting of bean and jack pine seedling cuttings. IBA and P‐ITB treatment at equal concentration were equally effective in inducing rooting of bean cuttings. However, in comparison with an equal concentration of IBA, P‐ITB treatment promoted greater rooting of jack pine seedling cuttings, but P‐ITB treatment was less effective than NP‐IBA treatment. Application of crystalline chemical to jack pine seedling cuttings indicated lesser toxic effects and earlier and greater root‐promoting effects of P‐ITB and NP‐IBA treatments, in comparison with IBA treatment. The earlier rooting of NP‐IBA‐treated jack pine seedling cuttings was positively related to increase in fresh weight of basal 1 cm stem before primordia were initiated. Weight of basal steins of NP‐IBA‐treated cuttings initially increased during propagation at day 2 in comparison with the control, and at day 3 in comparison with IBA‐treated cuttings. Results that were obtained with seedling jack pine cuttings were generally confirmed for cuttings from 7‐year‐old trees.