International Journal of Research in Plant Science

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1 Available online at International Journal of Research in Plant Science Universal Research Publications. All rights reserved ISSN Original Article Allelopathic activity of Ocimum sanctum L. And Tephrosia purpurea (L.) Pers. Leaf extracts on few common legumes and weeds. SHIVANGI PUROHIT AND NEETA PANDYA* Department of Botany, Faculty Of Science, The M.S.University of Baroda, Sayajigunj Authors id: Author s Phone no.: Corresponding author id: harmony2310@gmail.com* Corresponding author s phone no.: * Received 15 February 2013; accepted 27 February 2013 Abstract Allelopathy is a chemical interaction between plants, soil and microorganisms which shows inhibitory or stimulatory effect on others. Chemicals involved in this process are called allelochemicals, and are secondary metabolites of the plants. Medicinal plants contain large amount of various secondary metabolites. Basil (Ocimum sanctum L.) and Wild indigo (Tephrosia purpurea (L.) Pers.) are the medicinal plants containing various chemical compounds utilized for medicinal purposes. These compounds can also be utilized as allelochemicals to control weeds, and can be developed as bio herbicides, which can provide dual benefits to the farmers. Aqueous leaf extract of both the plants was prepared (1%,5%,10% concentration) and was tested on some legumes like Green gram (Phaseolus radiata (L.)Wilczek), Cow pea (Phaseolus unguiculata (L.)Walp), Pigeon pea (Cajanus cajan L.), Chickpea (Cicer arietinum L.), Black gram (Phaseolus mungo (L.) Heeper) and Moth bean (Phaseolus aconitifolius Jacq.). Some concentrations were also used to see the effect on Dichanthium annulatum L., Chloris barbata L., Acalypha indica L.and Amaranthus spinosus L. Study was conducted at laboratory condition to see the effect of extracts on seed germination and seedling growth. Objective of the study was to find out suitable concentration which inhibits weed germination but not of legume crops. The study shows that Basil and Wild indigo had differential effects on each legume at different concentration. Stimulatory effect was also observed while for weeds Wild indigo had a more inhibitory effect than Basil Universal Research Publications. All rights reserved Key words: allelochemicals, dry leaf aqueous extract, legumes, Basil (Ocimum sanctum L.), seed germination and growth, Wild indigo (Tephrosia purpurea (L) pers.) 1. Introduction Weeds are known to be one of the most significant agronomic problems, especially in organic farms where herbicides are not permitted for weed control. Besides mechanical weed control, use of organic residues as mulch is an alternative method of weed control in agriculture throughout the world [1]. Indiscriminate use of synthetic herbicides for weed control has resulted in very serious ecological and environmental problems, increasing incidence of resistance in the weeds to important herbicides such as S-triazines [5] and dinitroanilines are reported [8]. As traditional methods of discovering and developing new herbicides have become more difficult and expensive, interest in allelopathy for weed control and in natural products as source of new herbicide chemistries has increased [9]. Phenomenon of allelopathy through release of allelochemicals may be utilised in future to partially/fully replace synthetic herbicides. The knowledge of allelopathy has become necessary as increased interest in various agricultural systems such as inter cropping, multiple cropping, monoculture and no till planting [9].Allelopathy is described as all the chemical interactions among plants which can be stimulatory as well as inhibitory [7].It also refers to any direct or indirect inhibitory effect by one plant (including microorganisms) on another through the production of chemical compounds that escape into the environment [10].these chemical compounds that cause allelopathic influences on recipient species are called allelochemicals [12], and mostly are secondary metabolites produced by plants and are byproducts of primary metabolic processes [15].Majority of these secondary metabolites possess medicinal properties and their presence makes the respective plant medicinally important. The medicinal plants appear to be rich in various secondary metabolites, especially in leaves [21].Wild indigo (Tephrosia purpurea (L.) Pers) is widely available 5

2 plant in almost all parts of India, belonging to family Fabaceae. It has main chemical compounds like coumarins, flavonoids, rotenoids; quercetin.it is mainly utilized as a hepatoprotective, anticancerous, antibacterial, and fish poisoning agent.[1] While Basil(Ocimum sanctum L.) is cultivated in India for its medicinal and religious purposes.it belongs to family Lamiaceae and its leaves are rich in secondary metabolites like a steroid ursolic acid and n-triacontanol. Eugenol (70.5), its methyl ether (4.8), nerol (6.4), caryophyllene (7.5), terpinen 4-(0.4), decylaldehyde (0.2), selinene (0.4), pinene (0.4), camphene (2.0) and a- pinene (3.5%) Its main uses are as antistress, antiulcerogenic, antihypertensive, cough release and as insecticides [16]. These two medicinal plants were selected for present study to see their effect on few legume crops and their common associated weeds available in the field. Since long legumes in form of pulses have played a primary role in the search for vegetable sources of proteins owing to the high protein content of the seed, ranging from 20% in pea to 43.6 % in soyabean [2]. They can, therefore, be considered a good substitution to animal proteins in the human diet. India is placed third in pulse production (25% of total production) in all over world.in Gujarat (India) pulse cultivation is done on large scale and its production contributes 4% of total legume production of country. Objective of the study was to see the effect of selected medicinal plants on some common legumes and weeds, and to find out the suitable concentration of leaf extract which inhibits weed seed germination but not of the legume crops. Aim was also to find suitable combinations of medicinal plant and legumes which can be suggested for companion cropping which can provide dual benefits to the farmers, one as herbicide and other as medicinal plant. 2. Materials and Methods 2.1 Selection of plants: Selected crops were Green gram (Phaseolus radiata (L.) Wilczek), Cow pea (Phaseolus unguiculata (L.)Walp), Pigeon pea (Cajanus cajan L.), Chickpea (Cicer arietinum L.), Black gram (Phaseolus mungo(l.).heeper) and Moth bean (Phaseolus aconitifolius Jacq.).certified variety for each legume was selected which were GM-4,Gujarat -4,GT-1,Gujarat -1,Gujarat urd - 1,Gujarat -2 respectively. Selected weedswere Dichanthium annulatum L., Chloris barbata L., Acalypha indica L.and Amaranthus spinosus L. Selection was based on their frequent occurrence in selected crop fields around Vadodara district of Gujarat. 2.2 Collection of medicinal plants: Ocimum sanctum L. was collected from the local market and Tephrosia purpurea (L.) Pers. from the surroundings where it is growing wildly. 2.3 Preparation of leaf extract: Leaves were kept for drying in shade for one week, Then 10gm. of dry leaf powder was soaked in 100ml of distilled water for 24 hours to make 10% of total concentration. The extract was filtered with Whatman filter paper- 1 then by dilution with distilled water 5% and 1% concentrations were prepared. 2.4 Seed germination: Germination study was conducted in a 9cm. diameter Petri dish lined with one layer of Whatman filter paper no. 1, moisten with five ml of distilled water (control) or the extract (1%,5%,10%), on second day additional one ml of the extract was added. For each treatment three replicates were kept.ten seeds were kept for germination in each petriplate. Petri dishes were kept at room temperature, and daily observations were recorded. A seed is considered germinated when the radicle is protruded = 2mm [20] Seed germination and seedling growth were recorded. Seed germination (%) =100 (n/n) Where n is the number of seed germinated and N is the total number of seeds. Seedling growth- Seedling growth was assessed by root and hypocotyle length measurement When the seedling produced two leaves, they were taken to count of radicle and hypocotyle measurement, after five days for legumes and ten days for weed seeds as they took more time to germinate and grow. Seed vigour index (SVI) was calculated for legume seeds following modified formula of abdul-baki and Anderson (1973) SVI = germination percentage (%) * seedling length (cms.) 3. Result and Discussion 3.1. Seed germination Effect of Ocimum on legumes All the three concentration of dry leaf extract (1%, 5% and 10%) of Ocimum were showing negligible effect on legume seed germination. The germination rate of green gram was showing maximum resistance against all concentration. Stimulatory effect in germination was observed for Moth bean, Black gram, Pigeon pea, and Cow pea in all concentrations with compare to control (Fig.1). Figure 1. Effect of Ocimum on legume seed germination Only chick pea seed germination was inhibited by the treatments and inhibition increased with concentration, i.e. 1%,5%,and 10 % concentration shows 10%,20% and 40% inhibition respectively. Above results imply that Basil leaf extract is not inhibiting selected legume seed germination except the chick pea Effect of on Tephrosia legumes. Seed germination study for legumes with Tephrosia leaf extract shows individually distinct effects. Result shows (Fig. 2.) that minimum inhibition was observed with 1% concentration, especially for green gram and black gram which shows no effect as compared to control, moth bean and cow pea seeds show 95% and 90% germination respectively showing very less inhibition while, Pigeon pea and Chick pea germination was inhibited more as compared 6

3 to control.very less inhibition was observed in black gram and cow pea even at higher concentration i.e.at 5 & 10% Seed germination of selected legumes was showing very less inhibition with Ocimum leaves and low concentration treatment of Tephrosia leaf. Green gram and black gram seeds were most resistant against both plant treatments. Only chick pea shows inhibition with both leaf treatments, the germination percentage in control was also very less (only 40%) as compared to other legumes. Hypocotyle growth of legume seedling was also showing almost similar effect as on radicle. Black gram, moth bean and cow pea show stimulatory effect with treatment, which shows more growth of hypocotyle length than control. While chickpea, pigeon pea and green gram hypocotyle length show inhibition in Ocimum leaf treatment. A surprisingly 5% concentration showed stimulation for seedling growth of green gram as compared to 1% concentration (Fig. 4). Figure 2. Effect of Tephrosia on legume seed germination 3.2. Seedling growth The effect of Ocimum on legumes The seedling growth shows variable effect on different legumes (Fig.3). Radicle of all legumes, shows the stimulatory effect under Ocimum 1% leaf extract treatment, except green gram. Chick pea, black gram, moth bean and cow pea shows 20 to 50 % more radicle growth than control with 1% treatment. At 10% concentration of leaf treatment shows inhibition for the same legumes. To use this treatment against weed at low concentration (1%) is recommended, so that it will not cause any damage to legume crops in the field. Figure 4. Seed vigour index (SVI) of legume seeds with Ocimum treatment Seed vigure index of the legume seeds against ocimum leaf treatment gives the total effect of treatment on seed germination and seedling growth. All legume shows stimulation (Fig. 4) with treatment (1%) as compared to germination and growth in control seeds. Green gram shows 100 % germination with all treatment, but its seedling length was inhibited Figure 3. Comparative studies of radicle and hypocotyle growth of legumes under different concentration of Ocimum leaf extract Figure 5. Comparative studies of radicle and hypocotyle growth of legumes in different concentration of Tephrosia leaf extract Effect of Tephrosia on legumes. Legumes were showing negligible inhibition with Tephrosia in seedling growth. Here a leaf extract shows stimulation for radicle and hypocotyle length at higher concentration (i.e.5 % and 10%) than control and 1% 7

4 concentration. Radicle length (Fig. 5) Of all legumes were inhibiting (2-5%) at lower concentration compared to controls, but shows stimulation at higher concentrations Cow pea seeds shows a remarkable resistance against treatment as radicle growth was recorded more than control. Hypocotyle length of all legumes was induced by the treatment except chick pea and pigeon pea which shows 5 to 15% of inhibition with treatment. hypocotyle length in black gram and moth bean increased by 5% and 10% concentration by 1 to 1.5 cms than control. Seed vigor index (Fig.6) of legume seeds shows remarkable inhibition in pigeon pea and chickpea seedling growth with treatment as their germination was low with treatment while cow pea, black gram and moth bean shows stimulation with treatment as compared to control. Figure 6. Seed vigour index (SVI) of legume seeds with Tephrosia treatment Figure 7. Effect of of Ocimum and Tephrosia leaf extract on seed germination of selected weeds Effect of Ocimum and Tephrosia on weed seed germination Ocimum and Tephrosia leaf treatment were showing individually variable inhibitory and stimulatory effect for seed germination and seedling growth of legumes. On the basis of above data minimum concentration (1%) was selected for weed germination treatment (Fig 7). So that it will not cause any harm to the crops, if applied in the field. Lower concentration was applied for germination and seedling growth of selected weed seeds. Ocimum at 1% shows maximum inhibition to Amaranthus (80%) followed by Chloris (10%) while no effect on Acalypha and Dicanthium seed was observed. While tephrosia leaf shows more inhibition, especially in Amaranthus (90%) followed by Acalypha indica (66%), and 45% inhibition in both monocot weeds; Chloris barbata and Dicanthium annulatum. Both dicot weeds were showing more inhibition than monocots. Weeds were not showing the effect on seedling growth in lab condition. 4. Conclusion The use of legume green manures is complicated, because of potential problems with phytoxicity of the residues for several weeks following incorporation into the soil [1,3,14]. This phenomenon was recognized in the early part of the last century, and recent studies have confirmed that legumes used as green manures can serve as sources of chemicals that suppress plant germination and growth [17,18]. Although allelopathy has been suggested as a potentially important component of new weed-management systems [12], a well-defined strategy has yet to be developed for exploiting the phytotoxicity of legume green manures selectively, so that weed species are suppressed but crops are not. Tephrosia is widely available and belongs to the Leguminosae family so apart from its medicinal uses, it can be utilized as nitrogen source for many plants if grown as a cover crop or intercrop, which can give double benefits for the crop as natural herbicide ad well as a nitrogen source. It is based on their preliminary surveys reported that Cassia sericea, C. tora, Tephrosia purpurea and Croton bonplandianum restricted Parthenium invasion in many states in India [19,20]. It can give benefit to farmer also as it is a medicinally important plant and can play a role of bio herbicide. Ocimum also can be utilized as a cover crop as it has insecticidal and medicinal properties.for some weeds it shows the allelopathic effect also. Aqueous extracts of Ocimum americanum significantly inhibited the germination and seedling growth of Parthenium [11]. One study shows that 30% aqueous concentration of Ocimum sanctum shoot inhibits seed germination of Parthenium by 70% [6] From the lab experiments of Ocimum and Tephrosia dry leaf water based decoction with six legumes and four weeds for their germination effect and seedling growth, we can conclude that Tephrosia shows more inhibitory effect than Ocimum. Higher concentrations of tephrosia leaf extracts were inhibitory to crop seeds while weed seed germination was inhibited even at low concentration. thus 1% concentration can be recommended for selected weed control. Among legume crops, the chickpea is sensitive towards all treatment while black gram, green gram and moth bean are more resistant. In weeds, Amaranthus spinosus and Acalypha indica shows more inhibition towards treatment than monocot weeds. 5. Reference 1. D. R.Batish, H. P. Singh, R. K. Kohli, S. Kaur. Crop allelopathy and its role in ecological agriculture. (2001) in R. K. Kohli, H. P. Singh, and D. R. Batish, Eds. Allelopathy in Agroecosystems. Binghamton, NY: Haworth Press. 2. P. Cereletti, The Legume Proteins. Proc. Congr. PPI. 30 May -2 June, Perugia, Italy. pp substrates of central Newfoundland. Forest Ecology and Management 23 (1979)

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