Crop Protection & Environmental Biology

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Allelopathic effect of pentaclethra macrophylla benth. leaf extracts on germination and seedling growth of maize and okra
(2020) Ogbu, J.U.; Awodoyin, R.O.; Olubode, O.S.
Pentaclethra macrophylla Benth. is an indigenous leguminous tree of southern Nigeria's agroecosystems, whose seeds are used as spices; however, its allelopathy potential is not understood. Therefore, this study was aimed at investigating P. macrophylla allelopathic effects on germination and seedling growth of maize and okra. Materials and Methods: Allelopathic effects of Aqueous Leaf Extracts (ALE) of P. macrophylla at 0 (control), 10, 20, 40 and 80% concentrations on maize (n = 200) and okra (n = 200) seed germination and seedling growth were assessed in laboratory and screen house nursery. Total germination (%) for both crops was determined at one Week After Sowing (WAS); while Number of Leaves (NL), Plant Height(PH) (cm), Root Length (RL) (cm) and Dry Weight (DW) (g) were evaluated at 8 WAS. Experimental design used in the study was completely randomized design. Data were analyzed using descriptive statistics and ANOVA at a0.05. Results: Above 90.0% germination was recorded for maize in all the ALE concentrations, while for okra ALE-10 gave significantly highest germination (90.0±8.7%) and ALE-80 gave least (42.5±26.3%). Maize and okra seedlings given ALE-40 had highest NL, PH and DW;* while ALE-0 (control) had least values in PH and DW, respectively. Control had highest RL in both crops. The ALE-10 gave least RL in maize and ALE-20 gave least RL in okra. Conclusion: Pentaclethra macrophylla aqueous leaf extract at 10% enhanced germination, while 40% concentration encouraged dry matter accumulation and height in maize and okra seedlings.
Allelopathic effects of aqueous extracts of olax subscorpioidea oliv. on seed germination and growth of okra (abelmoschus esculentus (l.) moench) in Ibadan, Nigeria
(2022) Ayoola, D.O.; Olubode, O.S.
Allelochemicals are being explored as environmentally friendly options in weed management and crop yield improvement as opposed to use of synthetic pesticides which have serious environmental damages. Allelopathic effects of aqueous extracts of different parts of Olax subscorpioidea on Okra seed germination in Petri-dish bioassays and okra performance in pot experiment were conducted in the Department of Crop Protection and Environmental Biology, University of Ibadan using a complete randomized design (CRD) and with treatments replicated five times. Ten okra seeds in three replicates were treated in separate petri-dishes with 2 ml water extracts of stem, leaf, fruit, bark and root of Olax subscorpioidea, and 2 ml distilled water (control) in two trials. Pot trials was carried out using okra seedlings with treated with 100 ml extracts at seven days intervals. Data were collected on number of germinated seeds daily and lengths of five randomly selected plumules and radicles at 7 days after sowing (DAS). Number of leaves, plant height, root and shoot dry weight of seedlings were also measured using standard methods. Data were analyzed by analysis of variance. Statistically significant (P<0.05) means were separated using Duncan’s Multiple Range Test. Leaf extract had the highest concentrations of phenolic, flavonoid and saponin compounds compared, while the stem extract had the least metabolite concentrations. Leaf extracts exerted highest inhibition on okra germination at 2 and 7 DAS in the first trial and at 7 DAS in the second trial compared to the bark, stem, root and fruit extracts of Olax subscorpioidea. The seedling growth and yield parameters in treatment extracts were better than control. In conclusion, Olax subscorpioidea has allelopathic potential with effects on germination and seedling growth of okra. It can be used as an alternative bioherbicide. Its production and agricultural potentials should be promoted.
Phytotoxic effects of aqueous extracts of olax subscorpioidea oliv. on seed germination and growth parameters of maize (zea mays l.)
(2020) Olubode, O.S.; Ayoola, D.O.
Phytotoxicity of wild plants is sometimes utilized in the control of weeds. Their effects on crops are however not extensively documented. Effects of aqueous extracts of Olax subscorpioidea Oliv. were thus examined on seeds and seedlings of maize. Two experiments were laid out in complete randomized designs (CRD) and replicated five times. Ten seeds of maize were initially placed in separate petri-dishes and moistened daily with two (2) ml water extracts of different parts of Olax sp. while 2 ml of distilled water served as control. Secondly, maize seedlings growing on top soil in experimental pots were treated with 100 ml of extracts at seven days intervals for eight weeks. Data were collected on number of germinated seeds daily, and lengths of five randomly selected plumules and radicles at 7 days after sowing (DAS). Number of leaves, plant height, root dry weight and shoot dry weight of seedling were measured using standard methods. Analysis of variance and Duncan’s Multiple Range Test were conducted to statistically determine significant means at P=0.05. Mean germination of (0.71±0.00) was observed at 2 DAS and 2.81±0.10 at 7 DAS. Leaf extracts significantly reduced germinability, but significantly increased number of leaves, plant height (26±1.28), root dry weight (10.30±3.24) and shoot dry weight (14.99±2.13). The results showed that Olax subscorpioidea has alloallelopathic (phytotoxic) effects on maize seeds, but stimulated growth of maize seedlings. Its use as a bio-herbicide or growth stimulant in should be well-timed.