Assessment of interspecific competition between Abelmoschus esculentus ( L . ) Moench and Pennisetum glaucum ( L . )

Intercropping is practiced to maximise crops productivity and the, maximum use of the available resources of the plants. Usually, it is practiced for cooperation among the plants but plants also start competition with other plants. The stronger competitor may be more benefited. Therefore, care must be taken when intercropping is practiced. In this paper, interspecific competition between Abelmoschus esculentus L. Moench and Pennisetum glaucum (L.) R.Br. is reported. Various growth parameters were compared in monocropped and competitive conditions. The height of A. esculentus was less affected by P. glaucum when intercropped. The number of leaves and branches of A. esculentus were significantly higher in control as compared to competition. Number of flowers and fruits in A. esculentus were more in monocropped than for intercropped A. esculentus.


Introduction
Intercropping ensures efficient utilization of light and other resources, reduce soil erosion, suppress weed growth and thereby help to maintain greater stability of crops yield [1]. Intercropping is growing of two or more crops in close proximity to promote interaction between them and is practiced with the aim of maximizing plant cooperation rather than plant competition for maximum crop yield per unit area [2].Plants need nutrients, water and sunlight CO2 and O2 for their growth and reproduction processes.Nutrient and water present in the soil where from they are absorbed by the plant roots.Sunlight, CO2 and O2 are taken from the atmosphere.When plants grow together they compete for all these resources.Competition is a harmful hindrance of one individual over another [3, 4].Grime [5] argued that best competitors are those species with characteristic traits having maximum competitive effect.Tilmen [6] elaborated that a good competitor has maximum competitive ability and to tolerate the depleted resources level.Clements et al.
[7] pointed out that two plants compete whenever the available resources are deficient in the environment.Plants compete for water, nutrients, space, light etc and their environment will determine which species will make their existence

Materials and methods
Field experiment was performed in botanical garden Islamia College Peshawar, to investigate the interspecific competition between P. glaucum L. and A. esculentus L. Six plots of 1×2m were prepared for the experiment.The plots were frequently watered so as to leach out any possible biochemical substances. A. esculentus L. and P. glaucum L. were grown alone in plot 1 and 2 respectively whereas in plot 3, 4, 5, and 6 A. esculentus L. and P. glaucum L. were grown together.Intercropping was done in such a way there was one intercrop row between two adjacent P. glaucum L. rows.Inter row distance was kept 10 cm [18].Five plants from each plot were selected randomly to calculate data for various vegetative and reproductive growth parameters.The plants were selected from the middle rows of plots so as to ensure the maximum competitive effects.Data of different parameters was taken at interval of 10 days.The crops were irrigated at regular intervals.Uniform quantity of water was supplied according to all the plots.All other conditions such as light and temperature etc. were also kept uniform.1B).Similar results were shown by Olasantan [37] by Intercropping A. esculentus and Zea mays L. This might be due to competition between these two crops for available resources.Besides nutrients there might be some chemicals released by one plant that inhibit growth and nutrients absorption of other plant.Number of flowers and fruits were also more in monocropped A. esculentus L. than for intercropped A. esculentus L (Figure 2B  and 2C).This view was also supported by who reported that greater number of pods produced for monocropped A. esculentus could have been influenced by greater number of branches and leaves per plant.

Results and discussion
This view was also supported by who reported that number of pods would depend on the intensity of growth of plant.The number of leaves and branches of A. esculentus L. were more in control as compared to in competition (Figure 1A and  2A).This might be due to shading effects of P. glaucum on A. esculentus, because light is an important factor in competition to determine the leaf area [38].Decrease in leaf growth may be due to the competition of roots for absorption of nutrients from the common rhizosphere.Distribution of root might affect the root and shoot ratio and consequently affected the efficiency of using moisture and nutrient resources [38-40].

Figure 1 .
Figure 1.Interspecific competition between A esculentus and P glaucum.Figure 1A represents number of leaves and Figure 1B represents height.Six plots of 1×2m were prepared and plants were grown separately and in competition.Errors bars represent the standard errors

Figure 2 .
Figure 1.Interspecific competition between A esculentus and P glaucum.Figure 1A represents number of leaves and Figure 1B represents height.Six plots of 1×2m were prepared and plants were grown separately and in competition.Errors bars represent the standard errors

31, 32].
Zea mays L., Glycin max L., Vicia faba and Sugar beet [ esculentus L. and P. glaucum L. The height of A. esculentus was less affected by P. glaucum L (Figure