Influence of various temperatures, seed priming treatments and durations on germination and growth of the medicinal plant Aspilia africana

Abstract

For millennia, Aspilia africana has been used across Africa to treat various diseases including malaria, wounds, and diabetes. In this study, temperature influenced the in vitro germination of A. africana with highest final germination percentage (FGP) and germination index (GI) of 65.0 ± 7.64% and 2.26 ± 0.223, respectively, at 19.8 °C. Priming seeds with H₂O, KNO_3, and GA₃ (gibberellic acid 3) improved both in vitro germination and ex vitro emergence of A. africana seeds. Seed priming with [Formula: see text] M GA₃ produced overall highest in vitro FGP (from 90.0 ± 4.08% to 100 ± 0.00%) and GI (from 2.97 ± 0.385 to 3.80 ± 0.239) across all priming durations. Seeds primed with KNO₃ had better germination parameters for 6 and 12 h compared to 18 and 24 h. Furthermore, the highest in vitro FGP (100 ± 0.00%) was observed in seeds primed for 12 h with [Formula: see text] M GA₃. Ex vitro A. africana seed emergence was significantly enhanced by GA₃ priming. Priming A. africana seeds with H₂O, KNO₃, and GA₃ improved their growth after 3 months, with the overall best growth for seeds primed with [Formula: see text] M GA₃. Seed priming of A. africana is a feasible approach for improving germination and seed emergence, and enhancing plant growth.

Figure 1

(a) Summary of sterilization process of A. africana seeds. (a1) Arrangement of A. africana seeds in a Petri dish (a2) Illustration of arrangement of A. africana seeds in a Petri dish (b) Seeds of A. africana in Petri dishes incubated in a thermogradient germinator at different temperatures (1–17.6 °C, 2–18.7 °C, 3–19.8 °C, 4–20.9 °C, 5–22.0 °C, 6–23.1 °C, 7–24.2 °C, 8–25.3 °C, 9–26.4 and 10–27.5 °C.

Figure 2

Effect of temperature on in vitro seed germination parameters of A. africana. (a) Final Percentage Germination (b) Germination Index (c) Mean Germination Rate (d) time required for 50% germination (T₅₀). Values are presented as means ± standard error. ns-not statistically significant by Tukey’s multiple comparison test and p = 0.05.

Figure 3

Effect of priming treatment on ex vitro seed emergence parameters of A. africana. (a) Final Percentage Germination (b) Germination Index (c) Mean Germination Rate and (d) time required for 50% germination (T₅₀). Values are presented as means ± standard error. Same letters are not significantly different by Tukey’s multiple comparison test and p = 0.05.

Figure 4

Comparison of shoot and root lengths of sampled representative A. africana plants derived from hormo-, halo- and hydro primed seeds after three months of growth (a) $1.44\times {10}^{-3}$ M GA₃ (b) $2.89\times {10}^{-4}$ M GA₃ (c) $2.89\times {10}^{-5}$ M GA₃ (d) 1.0 M KNO₃ (e) 0.5 M KNO₃ (f) 0.1 M KNO₃ (g) Distilled water (h) Non treated.

Figure 5

Effect of priming treatment on early growth of A. africana. Growth parameters measured after three months of growth. (a) Shoot length (b) Number of leaves (c) Root length (d) Number of roots (e) Fresh weight (f) Dry weight. Values are presented as means ± standard error. Same letters are not significantly different by Bonferroni’s test and p = 0.05.