Effect of Root Pruning on the Root Growth Potential (RGP) of Three Philippine Native Tree Species

Abstract

Root growth potential (RGP) is the plant’s capacity to grow new roots, an important trait for seedlings to be used on any reforestation program. In the Philippines, these kinds of programs often end up in failure, as low-quality seedlings are usually chosen due to unfamiliarity with attributes that indicate good outplanting performance, narrow sources of high-quality seeds, and the lack of a reliable quality assessment method. This study aimed to determine the RGP of three native species – namely, bignai (Antidesma bunius), kamagong (Diospyros blancoi), and molave (Vitex parviflora) – and find its correlation with other morphological parameters. The experiment was done in a completely randomized design (CRD) with taproot pruning lengths (1-cm pruning, 2-cm pruning, and no root pruning) applied as treatments for each species. The morphological parameters measured included the relative growth rate (height and diameter), number of leaves, root collar diameter (RCD), biomass (root, shoot, and total) and length of taproot while root-shoot ratio, sturdiness quotient, and seedling quality index (SQI) were calculated. In general, taproot pruning had no significant effects on the seedling morphological attributes of all species. Excluding molave, the two other species had mostly responded well to root pruning and can be recommended as a treatment to induce root growth development. RGP had generally complemented the results from the other parameters, indicating how root development was associated with the morphological growth of the species. The study shows how RGP can also be relied on for testing seedling health and the status of native species. For a more comprehensive result, future research could increase experiment duration or use younger seedlings. A field performance assessment could also be performed to supplement the RGP study