Improving Regeneration of The Endangered Millettia Laurentii De Wild: Effect of The Substrate, Leaf Area, Auxin and Leaf Fertilizer on The Rooting Ability of Stem Cuttings
Abstract:
Vegetative propagation of tropical tree species through cuttings is an important alternative for mass multiplication of high-quality species for large-scale reforestation programs. In this way, multiplication of Millettia laurentii through cuttings is an asset for improving the cultivation and regeneration of this endangered species for its conservation. It is in this order of ideas that a nursery study was carried out to assess the effect of substrate, leaf area, auxin and leaf fertilizer on the ability of rooting under non-mist propagator. This equipment is designed to maintain a humid environment and reduce water loss through transpiration and evaporation. The non-mist propagator is a wooden box of 3 m long by 1 m high which consists of three equal-dimension compartments. The experimental setup consisted as follow; Test 1: combined effect of leaf area and type of substrate on rooting of stem cuttings; Test 2: combined effect of foliar fertilizer and rhizogenic hormone treatments. The parameters for evaluation were: mortality rate, rooting rate and average number of roots. The data collected were edited in Excel 2010 software. Subsequently, they were subjected to analysis of variance using the software IBM SPSS 20, general linear multivariate model. Means were separated using the smallest significant difference. The chosen probability threshold was 5%. The results of propagation tests show that rooting ability is significantly influenced by leaf area and auxin concentration. Cuttings with a leaf area of 100 cm² had the best rooting rate, 88.89%. Application of various concentrations of the growth hormone produced significant positive effects on the rooting rate and the number of roots produced. The most effective propagation factors were the leaf area (100 cm²) and the 100-µg concentration of Indole-3-butyric acid (IBA). The results of this study are of great interest in improving propagation for sustainable cultivation and regeneration of this threatened tree as well as the conservation of forests for it allows the development of appropriate and efficient propagation methods for mass production of high-quality plant material for this species.
