Abstract
The allelopathic effect of three tree species (Azardiracta indica, Vitellaria paradoxa, and Parkia bi-globosa) on germination and growth of cowpea was investigated in the Southern Guinea Savannah agro ecological zone of Nigeria. The experiment was laid out in Randomized Complete Block Design (RCBD) with three (3) replicates. Data were collected on germination, plant height, stem diameter, number of leaves, number of branches, root length, the above grand biomass and the below grand biomass and were subjected to statistical analysis using Analysis of Variance (ANOVA) while the significant mean was separated using Duncan’s Multiple Range Test (DMRT) at 5% possibility level. Results showed that the tree species brought about considerable inhibition in the germination of cowpea seeds and in its growth parameters. The statistical germination value of the cowpea seeds under the tree species had decreased value thus indicating that growth inhibitions were seriously felt. It was apparent that Parkia biglobosa (53.33) and Vitellaria paradoxa (60.00) had more inhibitory effect on cowpea seeds germinability than that of Azardiracta indica. (63.33) while all the treatments are lower than that of control (100). The tree species had similar inhibition capability in the cowpea plant height, stem circumference, number of leaves, above grand biomass and below grand biomass. However, in all treatment, statistic showed that there is no significant difference (p
Highlights
Allelopathy has been defined as an adverse influence or interference of one plant or microorganism on another (Rice, 1984)
The results obtained from the plants under these tree species were compared statistically to those obtained from the control experiments following the procedure of analysis of variance (ANOVA) where differences were observed, Duncan’s Multiple Range Test (DMRT), at 5% level of probability, was used to compare differences among the treatment means
Results of the present study showed that the tested tropical tree species inhibited the germination of the cowpea seeds
Summary
Allelopathy has been defined as an adverse influence or interference of one plant or microorganism on another (Rice, 1984). Association and dissociation pattern between certain plant species are widely known Such phenomenon may be governed by direct competition for necessary growth factors or through addition of allelopathic chemicals into the soil environment (Einhelling, 1996; Ashrafi et al, 2007). It has been documented that allelopathy may play an important role in plant-plant interference by those chemical compounds (Inderjit & Dakshini, 1992). Some of those compounds are released into the environment through leaching, litter decomposition, root exudation or direct volatilization, and could affect (either positively or negatively) germination and growth of other species (Gross & Parthier, 1994; Seligler, 1996). Chemicals with inhibitory activity are present in many plants and in many organs, including leaves, flowers, fruits and buds (Inderjit, 1996; Ashrafi et al, 2007)
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