Seed germination characteristics of selected native plants of the lower Rio Grande Valley, Texas

Abstract

Experiments were conducted to identify treatments that increased emergence of seeds of 24 woody plant species native to the lower Rio Grande Valley of southern Texas. Sulfuric acid (18.4M H2 SO4) scarification significantly increased emergence of huisache (Acacia smallii), huisachillo (A. schaffneri), Texas ebony (Pithecellobium flexicaule), tenaza (P. pallens), tepeguaje (Leucaena pulverulenta), retama (Parkinsonia aculeata), and western soapberry (Sapindus drummondii); treatments such as soaking in distilled water, gibberellic acid (0.3 or 1.4 mMol), or other scarification techniques were not as effective as acid. Fresh guajillo (A. berlandieri) seeds required no treatment, but 8-month-old seeds had higher emergence with acid scarification. Texas ebony emergence was higher from 10-month-old seed treated with acid than from fresh seeds. No pre-treatment seemed necessary for seeds of coral bean (Erythrina herbacea), Texas persimmon (Diospyros texana), sugarberry (Celtis laevigata), granjeno (C. pallida), pigeon-berry (Rivina humilis), Texas baby-bonnets (Coursetia axillaris), guajillo (A. berlandieri), and lotebush (Ziziphus obtusifolia). Results with blackbrush (A. rigidula), Wright's acacia (A. wrightii), rattlebush (Sesbania drummondii), guayacan (Guaiacum angustifolium), brasil (Condalia hookeri), elbowbush (Forestiera angustifolia), and anacua (Ehretia anacua) seeds were inconclusive. Plants of 16 woody species achieved mean heights of 25 cm in 45 to 150 days.