Received date: December 07, 2018; Accepted date: December 12, 2018; Published date: December 28, 2018
Citation: Ismil R, Hirai N, Fujii Y (2019) Plant Growth Inhibitory Activity of Goniothalamus andersonii Bark Incorporated with Soil on Selected Plants. Eur Exp Biol Vol. 9 No. 1:1. doi: 10.21767/2248-9215.100078
Copyright: © 2019 Ismil R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Phytotoxic effects of soil incorporation with Goniothalamus andersonii bark powder against Cucumis sativus (cucumber), Trifolium repens (white clover), Lactuca sativa (lettuce), and Lolium perenne (perennial ryegrass) were evaluated under the greenhouse condition for possible utilization as weed suppression. The growth of tested plants was reduced significantly after 14 days of incorporation where the degree of inhibition was dose dependent. A monocotyledonous plant, L. perenne was greatly inhibited by 94.8% when exposed to the bark powder concentration of 2% (w/w). After 21 days of incorporation, the length and fresh weight of both root and shoot part of tested plants were decreased significantly. These results indicate that G. andersonii bark possess inhibitory activity against various tested plants, suggesting that the bark powder is very beneficial as natural herbicide in weed control management.
Phytotoxic effects; Soil incorporation; Goniothalamus andersonii; Lolium perenne; Weed control
Allelopathy is defined as the interaction between plants, including microorganisms which have detrimental or beneficial effects through the release of chemical compounds into the environment . The liberation of secondary metabolites into the environment by living or dead plant tissue occurs through several ways namely volatilization, root exudation, leaching and decomposition of plant residues in soil [1,2]. This will interfere with the growth and development of neighbouring plants or other organisms.
Excessive use of synthetic herbicides has been negatively affected human health and environment as well as rapid development on herbicide-resistant weeds [3,4]. The application of herbicides is being prevented due to the effect of its residue, non-target toxicity and long-term perseverance in soil . Therefore, the demand for natural herbicide is increasing as it is ecologically friendly and easily biodegradable.
The use of plant residue with allelopathic properties incorporated into soil known as one of the alternatives in weed management. The weed germination and growth can be inhibited by various applications of allelopathic crops and allelochemicals as extracts, mulches and residues . The retardation of seed germination and individual plant growth inhibition are adversely affected by soil incorporation or surface application, such as mulch of allelopathic crop residues. This phenomenon resulted in the reduction of weed community density and vigor as a whole . The effective and success use of cover crops as mulches or incorporated into soil to control weeds has been reported in several literatures. For example, the density and biomass of some weeds were significantly decreased as affected by the mulching or incorporation of legumes or cereals [8-10].
Goniothalamus andersonii J. Sinclair, from the family Annonaceae is an aromatic medicinal plant, endemic to Sarawak. This plant is widely used in traditional medicines by natives especially for abortion and post-partum treatment. Our previous study indicated a great allelopathic activity of the bark part of this plant. Goniothalamin was isolated and identified as its predominant plant growth inhibitor . However, the phytotoxic effects of this plant residue in soil have not yet been investigated. Therefore, current research was conducted to evaluate the plant growth inhibitory activity of G. andersonii bark residue incorporated into soil against C. sativus, T. repens, L. sativa and L. perenne as tested plants for possible application as bioherbicide.
The bark of Goniothalamus andersonii was collected in Lundu, Sarawak and were oven-dried at 60˚C for 48 hours. The bark samples (100 g) were chopped into small pieces and grounded into powder by using a traditional grinder. The seeds of Cucumis sativus L. cv. Ora 2 were purchased from Kurume Vegetable Breeding Co., Ltd., Trifolium repens L. cv. Fia from Snow Brand Seed Co., Ltd., Lactuca sativa L. cv. Legacy from Takii and Co., Ltd. and Lolium perenne L. from Fukuokaen Seedling Co., Ltd.
The phytotoxic effects of bark powder from G. andersonii incorporated with soil on the growth of selected plants were evaluated in the greenhouse. The environmental conditions were 11h/13h day/night photoperiod, average day/night temperature of 36/14˚C and humidity of 78%. This pot experiment was conducted by integrating bark powder with soil (Kumiai Engei-Baido, Zen-no, Japan) at different bark concentrations of 0.1, 0.5, 1 and 2% (w/w). These treatments were prepared in three replications by using the pot of dimensions 55 mm diameter, 65 mm height (Agripot, BBJ High- Tech) as well as control treatment devoid of bark powder. One pre-germinated seed of tested plants were sowed in each pot and all those treatments were irrigated with adequate amount of water to keep them in moisture condition.
The height of tested plants was measured on the 7th, 14th and 21st day after incorporation. The inhibition (%) was calculated compared to the control treatment as follow:
Inhibition(%)=100-[(Average height for residue treatment/ Average height for control) × 100]
On the day 21st after incorporation, the length and fresh weight of both roots and shoots of tested plants were measured. For control treatment, the length (mm) of roots of C. sativus, T. repens, L. sativa and L. perenne were 122, 125, 84.0 and 135 while their shoot length was 118, 56.7, 96.7 and 168, respectively. In terms of fresh weight (g), the root weight of C. sativus, T. repens, L. sativa and L. perenne were 0.57, 0.08, 0.02 and 0.05 while their shoot weight was 2.17, 0.18, 0.37 and 0.24, respectively. The inhibition (%) was calculated compared to those values based on the above formula. EC50 values (%) which are the concentration of bark powder that inhibit 50% growth were determined based on those results.
The data gathered were analyzed by using Analysis of Variance (ANOVA). Tukey’s HSD test was used to compare between treatments at 0.05 probability level. The statistical software employed was Statistics 10 Analytical Software, Tallahassee, FL, USA. The EC50 values were determined by Probit analysis.
The effects of soil incorporated with G. andersonii bark powder on the growth of tested plants over time
The bark powder of G. andersonii incorporated with soil was tested against C. sativus, T. repens, L. sativa and L. perenne in order to evaluate its phytotoxic effects on those plants under the greenhouse condition. The growth of tested plants was decreased with the increasing concentration of G. andersonii bark powder on the 7th, 14th and 21st day after incorporation. The results showed various degree of inhibition based on the species tested as well as the treatment period.
Throughout the weeks, the inhibition rate trend was significantly inclined after 14 days followed by a slight decreased after 21 days of incorporation in most cases. On the contrary, the inhibition rate of cucumber was declined through time except for the application of 2% bark residue. Similar tendency exhibited by lettuce only at the lowest rate of 0.1%.
Growth of L. perenne exposed to 2% bark powder was strongly inhibited by 94.8% from week 2 followed by white clover with 93.9%. This shows the high sensitivity of both plants towards inhibitory substances from G. andersonii bark powder.
The effective concentration (EC50) which induced 50% inhibition was ranging from 0.23 to 0.81% (Table 1). The values were varied depending on recipient species and period of incorporation. The application of 0.31% bark powder incorporated into soil could reduce 50% growth of C. sativus. This was the lowest EC50 value as compared with other plants tested after 7 days of incorporation. After 14 days of incorporation, T. repens recorded the lowest EC50 value (0.23%) followed by C. sativus, L. sativa and L. perenne in an ascending order. Intriguingly, this result showed that the application of bark powder at 0.6% or less vigorously retarding 50% growth of tested plants.
|Tested plants||EC50 values (%)|
|Day 7th||Day 14th||Day 21st|
Table 1: Effective concentration (EC50) for growth of tested plants over time.
The effects of soil incorporated with G. andersonii bark powder on the growth and biomass of tested plants 21 days after incorporation
The growth of both roots and shoots of tested plants as well as their fresh biomass after 21 days of incorporation are shown in Figure 1. The inhibition rate (%) of roots and shoots of all tested plants increased parallel with the increasing concentration of bark powder incorporated into soil. There was a slight stimulation effects exhibited by C. sativus root and L. sativa shoot at the lowest concentration of bark powder (0.1%) with -15.3% and -2.8%, respectively. The sensitivity of root and shoot part of all plants varied depending on the species and concentration applied.
Figure 1: The effects of soil incorporated with different concentrations of G. andersonii bark powder on the growth and fresh weight (FW) of roots and shoots of tested plants: a) Cucumis sativus, b) Trifolium repens, c) Lactuca sativa and d) Lolium perenne on day 21st after incorporation (: root length, : root FW, : shoot length,: shoot FW).
Among all species tested, T. repens and L. perenne were the most sensitive towards bark powder of G. andersonii at the rate of 2% (w/w) in terms of root and shoot growth, respectively. Apparently, the root growth of T. repens was inhibited by 97.3% while 94.5% inhibition was recorded by L. perenne shoot.
Based on the EC50 analysis, T. repens recorded the lowest EC50 value in terms of root and shoot growth (Table 2). The soil incorporation with 0.32% and 0.39% bark powder could inhibit 50% growth of root and shoot, respectively. The results indicate that incorporation of bark powder at the rate less than 1% could retard 50% growth of all tested plants three weeks after application.
|Tested plants||EC50 values (%)|
Table 2: Effective concentration (EC50) for growth and fresh weight of tested plants on day 21st after incorporation.
The significant reduction in root and shoot biomass was in line with the decline of their length. The exposure of tested plants to the highest concentration of 2% bark powder greatly reduced T. repens root and shoot as well as L. perenne root fresh weight the most by the equal rate of 99%.
The effective concentration which can induce 50% fresh weight of all tested plants was ranging from 0.11% to 0.40%. Among all plants tested, L. perenne was the most sensitive for the root biomass while for shoot biomass, T. repens was the most sensitive.
The bark powder of G. andersonii incorporated into soil found to possess phytotoxic effects against C. sativus, T. repens, L. sativa and L. perenne. This was attributed to the allelochemicals including goniothalamin released by this plant residue into soil hampering the growth and biomass of tested plants. However, their inhibition rates were different depending on the species tested, dosage of bark powder applied as well as the period of incorporation.
The application of plant powder from various parts of plant including leaf, root, shoot and flower incorporated into soil are known to have a potent suppression effects on the growth of tested plants [12-15]. Different rate of inhibition was exhibited by C. sativus, T. repens, L. sativa and L. perenne. Similar trend was indicated by the exposure of various plants to Mexican sunflower leaf residue .
The increasing of inhibitory rate was consonant with the increasing of dose applied. There is a plethora of studies in line with this [16-18]. The greatest phytotoxic effects displayed after 14 days of treatment was parallel with the previous report  which stated that the phytotoxic activity of soil incorporation with itchgrass powder was effective up to 14 days after incorporation.
Ecological and physiological aspects of plants were one of the key factors affecting the sensitivity of plants towards plant growth inhibitory substances . The susceptibility of seeds towards allelochemicals was contingent on their size, where large-sized seeds display a lower sensitivity in contrast to smallsized seeds  as well as the permeability of seed coat . Present study was supported by those finding where a smallseeded plant, T. repens was the most sensitive towards plant growth inhibitory substances released by G. andersonii bark powder. In a laboratory bioassay conducted, this plant also reported to have a high sensitivity towards goniothalamin with the EC50 value of 40 μM on the radicle growth . The allelopathic potential demonstrated indicates that this plant not only possess phytotoxic effects in laboratory condition, but also in nature.
A potent deleterious effect was presented by a monocotyledonous plant, L. perenne treated with G. andersonii bark powder at the highest dose. This was uncommon since dicotyledonous plants are usually more susceptible to plant growth inhibitory substances in comparison with monocotyledonous plants . Therefore, this interesting finding indicates the possible utilization of G. andersonii bark as bioherbicide to control weeds.
The application of G. andersonii bark powder at the lowest rate slightly promoted the growth of cucumber root and lettuce shoot after 21 days of incorporation. Similar results exhibited promotion effects on the shoot growth and dry biomass of Trifolium alexandrium as exposed to the lowest concentration of Sonchus oleracues shoot residue [1,23], also stated that most organic compounds which possess suppression effects at some concentrations also stimulate at low concentrations.
Phytotoxic substances exuded from G. andersonii bark through the incorporation with soil significantly reduced the growth and biomass of C. sativus, T. repens, L. sativa and L. perenne. The suppression effect proved that this plant has a great potential as bioherbicide for weed management. However, the target species, dose of residue applied as well as the treatment period should be taken into consideration . Further research in the field is required in order to demonstrate this effect in natural condition.
We thank Mr. Yahud Hj. Wat and his team collectors for providing the plant materials from Sarawak, Malaysia.
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