Efficient propagation of citrus rootstocks by stem cuttings

Abstract

A simple multicomponent system is described that is effective for rapid propagation of a diversity of citrus rootstock genotypes by single node cuttings, including new hybrids and cultivars that are most commonly used as rootstocks. Efficiency of this system for rooting shoot explants of six important rootstock cultivars, Swingle, Cleopatra, US-802, US-812, US-897, and US-942 is compared in a repeated study. Many of the cuttings began to grow within 2 weeks after planting into potting mix. Growth for the resultant plants of different genotypes was compared through 20 weeks, and significant differences were observed. US-802 had the highest success in establishing growing plants at 8 weeks, with 82–91% of single node cuttings successfully rooted and growing, while Cleopatra was the least efficient with a 42–45% recovery of growing plants. Comparison of plant weight for cuttings and seedlings indicated that 12 week old nucellar and true-to-type seedlings are similar in size to 12–16 week old cuttings of the same cultivars. Plants of all rootstocks, whether cuttings or seedling-propagated, were observed to approach a dry weight ratio of 80% shoot and 20% root. Pronounced differences in the number and length of roots were identified among the rootstocks, indicating large differences in root structure that might be important in relation to eventual field plant health and growth. The commercial utility of the described methods is discussed.