Sciences in Cold and Arid Regions ›› 2019, Vol. 11 ›› Issue (5): 350-359.doi: 10.3724/SP.J.1226.2019.00350.

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Seed germination and seedling growth of Pycnanthus angolensis (Welw.) Warb., African false nutmeg

Sakpere A.M.A.   

  1. Department of Botany, Faculty of Science, Obafemi Awolowo University, Ile-Ife, Osun State 230103, Nigeria
  • Received:2019-08-09 Accepted:2019-09-28 Online:2019-10-31 Published:2019-11-12


This study investigated the germination behavior and seedling growth of Pycnanthus angolensis seeds. The germination study was carried out in the laboratory and included pretreatment studies and observation of the seed-germination process. For each treatment, three replications of 20 seeds were sown in a transparent plastic germination box (12cm × 22cm × 5cm) lined with moistened filter paper at room temperature. To monitor seedling growth, seedlings were transplanted into pots filled with topsoil and laid out in a completely randomized design. Ten seedlings replicated thrice were measured monthly; and the shoot height, leaf area, and root length, as well as the fresh and dry weights of the seedlings, were recorded. Results showed that mechanically scarified seeds exhibited the significantly highest germination percent (83.33%, P <0.005), followed by control seeds (70.83%), whereas seeds treated with 98% sulphuric acid (H2SO4) displayed the lowest germination percent (1.67). The endospermous seeds exhibited cryptogeal germination, while seeds stored for a month (with or without arils) failed to germinate. During seed germination, radicle protrusion continued with a pseudo-opening of the root, through which the brownish cotyledonary petiole was emitted, thus releasing the plumule at the posterior position. Moreover, P. angolensis exhibited a slow growth rate, attaining a shoot height of 73 cm within a year. The highest positive change in leaf number and area was recorded in the fourth month, a period during which the least change in shoot height occurred. The study concluded that mechanical scarification of the seeds ensured significant and faster germination than chemical scarification or no treatment at all. Additionally, P. angolensis displayed a cryptogeal germination, with the seedling growth of the tree species observed to be slow.

Key words: cryptogeal germination, cotyledonary petiole, pretreatment, tree

Figure 1

Pycnanthus angolensis: (a) dehiscent drupe; (b) hard, thin-coated seeds with reddish arils; and (c) hard, thin-coated seeds without arils"

Table 1

Effect of different seed pretreatments on germination of fresh Pycnanthus angolensis seed"

Treatment Germination rate Peak germination (days) Germination percent
Control (untreated) 2.53 28 70.83%±0.40b%
Mech. scarified 2.97 28 83.33%±2.36a%
H2SO4 (50%), 40 min 0.27 28 7.50%±0.35d%
H2SO4 (50%), 20 min 0.45 24 10.84%±0.341c%
H2SO4 (98%), 2 min 0.075 22 1.67%±0.00e%

Figure 2

The longitudinal section of Pycnanthus angolensis seeds: (a) before germination; both (b) and (c), after germination"

Figure 3

Germinating seeds of Pycnanthus angolensis shown at (a) day 4, (b) day 6, (c) day 7, (d) day 8, (e) day 21, (f) day 23, (g) day 25, and (h) day 30"

Figure 4

Germinating seeds of Pycnanthus angolensis shown at (a) day 32, (b) day 34, (c) day 38, and (d) before transplanting, respectively"

Figure 5

Five-month-old seedlings from freshly collected Pycnanthus angolensis seeds"

Figure 6

Growth rate of Pycnanthus angolensis seedlings (a) with respect to the number of leaves and the total leaf area and (b) the change in growth rate with respect to the number of leaves and the leaf area"

Figure 7

Change in the growth rate of Pycnanthus angolensis seedlings with respect to shoot height and root length from the first month to the twelfth"

Figure 8

Change in the growth rate of Pycnanthus angolensis seedlings with respect to the fresh shoot weight, root weight, and total plant weight from the first month to the twelfth"

Figure 9

(a) Growth rate of Pycnanthus angolensis seedlings with respect to dry matter (shoot weight, root weight, and total plant weight) from the first month to the twelfth; (b) Change in growth rate with respect to dry matter (shoot weight, root weight, and total plant weight) from the first month to the twelfth"

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