Allelopathic Activity of Three Weed Species against Morphological and Physiological Traits of Parthenium hysterophorus and Trianthema partulacastrum

Weed management is extremely important for sustainable crop production in all cropping systems. The use of weedicides is one of the best approach to keep the weeds under check but the repeated use of few selective herbicides is giving rise to problem of herbicide resistant weeds and environmental pollution. Therefore, it is imperative to identify plant species having herbicidal potential so that their bio-extracts may be used as more safe and effective novel weed management means. The present study was conducted to explore the allelopathic impact of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale on seedling growth of Parthenium hysterophorus and Trianthema partulacastrum. A completely randomized design was used for the experiment with four replications. Results indicated that lowest values of fresh weight (0.208 mg) and shoot length (3.83 cm) of Parthenium hysterophorus seedling was observed when extract of Sisymbrium orientale was applied. Moreover, lowest values of fresh weight (0.1255 mg) and dry weight (0.0084 mg) of Trianthema partulacastrum seedlings was observed when Sisymbrium orientale extract was applied. However, maximum leaf area and electrolyte leakage of Parthenium hysterophorus and Trianthema partulacastrum seedlings was observed when Parthenium hysterophorus extract was applied. It is concluded that S. orientale extract have comparatively more active substances with ability to suppress germination and growth of weeds which could be exploited as prospective source of bio-herbicides.


INTRODUCTION
Weeds are present everywhere in the field and hamper the germination, growth and yield of nearly grown crops. They compete with the crops and reduced seedling growth by the release of different allelochemicals (Hayyat et al., 2020). Weeds are recognized as the global threat to agro and natural ecosystems (Shabbir et al., 2018). Extensive weed invasion has been the reason for more than one-third of the loss in crop yield of crops that grownup all around the world (Jabran et al., 2015). Weeds can cause production losses up to 35-69% in mung bean, 15-40% in cotton, 58-85% in soya bean, 10 to 100% in rice, 10-60% in wheat and 25-93% in maize (Kolhe et al., 1998;& Yaduraju et al., 2015).
Parthenium (Parthenium hysterophorus L.) is invasive weed belongs to Compositae family. It is originated from tropical America and nowadays occurs widely in the Australia, Asia and East Africa. It is observed to grow on the gardens, road sides, waterways, in grasslands and crop fields both during the season and after crop harvest, as long as enough moisture is available. This weed is becoming a problem for crop, range and forest. Similarly, Trianthema portulacastrum L. belongs to Aizoacae family and which is native to Southern Africa and has been reported to be present in Pakistan, India, West Asia, Tropical America, Africa and Sri Lanka. It has become noxious due to the reduction of substantial yield in several cultivated areas (Kaur & Aggarwal, 2017). Currently, both of these problematic weeds have been controlled by employing synthetic herbicides and herbicides are proved very effective while extensive use of these chemicals are causing negative impact on environment by accumulation in water and soil in addition to their effect on the biological diversity (Al-Samarai et al., 2018). Moreover, these pesticides are persistent in nature and cause health hazard for agro-ecosystem and living beings (Sharma et al., 2019). In addition to this repeated use of herbicides with same modes of action cause a strong selection pressure on the target populations of weeds with consequence that various cases of the resistance herbicides have been evolved worldwide (Powles & Yu, 2010). By the August 2018, resistance had been confirmed in about 255 weed species in the 92 crops in about 70 countries, affecting the efficiency of 163 various herbicides from the 23 well known herbicides (Heap, 2018). The increasing resistant weeds number biotypes is a major concern for the horticulture, agriculture, and amenity situations, especially as no new developed herbicide action mode has been marketed for over 30 years (Westwood et al., 2018). So, to overcome this developing condition there is a need to control weeds by bio herbicides. However, the quality and concentration of such natural bio-chemical compounds may differ based on weed species, different plant parts such as rhizomes, roots, leaves, stems, flower, pollen, seeds and fruits. These effective biochemicals are discharged from parts of the plants in the environment by diffusion, leakage from the parts of plants that are above ground, evaporation and disintegration.
These discharged allelochemicals are one of the most significant regulating factors in plant community structure (Gawronska & Golisz, 2006;& Aziz et al., 2020). Hence an experiment was designed to explore the impact of Adiantum capillusveneris, Parthenium hysterophorus and Sisymbrium orientale on seedling growth of Parthenium hysterophorus and Trianthema partulacastrum.

MATERIALS AND METHODS Plant extract preparation
The naturally growing plants of three weed species namely, Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale were uprooted from soan valley during their flowering stage. The plant samples were cleaned twice with the distilled water to eliminate any kind of contamination. These samples were placed separately at room temperature for shade drying with zero periods of sunlight. After shade drying electric blender was used for individually grinding of each part (leaves, stem and roots) to make fine powder.
After grinding, fine powder was preserved in tightly sealed plastic zipped bags to avoid the contact of moisture with powdered sample. Experimental site, design and treatments Wire house experiment was conducted at College of Agriculture, University of Sargodha. The study was conducted in CRD with four number of replications. The effects of three plants extracts (Adiantum capillusveneris, Parthenium hysterophorus and Sisymbrium orientale) was evaluated on two weed species namely Parthenium hysterophorous L. and Trianthema portulacustrum L. Experimental procedure and data recorded Firstly, pots having 9 cm depth were filled with the 500 g fine soil and ten seeds Parthenium hysterophorous L. and Trianthema portulacustrum L. were planted uniformly in pots. After germination of crops and weeds at three leave stage, foliar application of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale was done according to the treatment plan. The distilled water treatment was applied as control treatment. The data regarding seedling fresh biomass (mg), seedling dry biomass (mg), root length (cm), shoot length (cm), electrolyte leakage (%), leaf area (mm 2 ) and chlorophyll content (Spad value) was recorded. For seedling fresh biomass samples were taken 10 days after application of extract. Then fresh weights of samples were recorded with the help of weight balance. For dry biomass (mg) seedling were firstly dried in the oven for 48 hr at 64°C. After complete drying, dry weights of all collected samples were recorded with the help of weight balance. For root length ten seedlings from every treatment and replication were selected at random and length was measured. Then average root length was calculated. For shoot length (cm) ten seedlings from each treatment and replication were taken at random and shoot length was measured in cm from base to top of seedling. Then average shoot length was worked out. For electrolyte leakage (%) leaf sample was taken from all treatments and replications separately. Each sample was placed in 20 ml distilled water for 24 hr and EC was taken by EC meter and denoted as EC 1. Then these solutions were autoclaved for 15 minutes and again EC was measured as EC 2 . Electrolyte leakage was calculated by the equation (Whitlow et al., 1992).
For leaf area (mm 2 ) five plants were selected from every pot and leaf area was noted by using leaf area meter (CI-202, Portable Laser Leaf Area Meter). For chlorophyll content (SPAD value) five plants were selected from each pot and SPAD (Soil Plant Analysis Development) chlorophyll values from the 3 topmost fully opened leaves of these plants were recorded by chlorophyll meter (Yaxin, 1260). The mean SPAD values were calculated by using standard procedure (Peng et al., 1993).

Statistical analysis
The data observed and collected was analyzed by using Fisher's analysis of variance technique and means were equated at 5% significance level by using Honestly Significant Difference Test (Steel et al., 1997).  (Table 1). The data indicated that maximum leaf area (43.53 mm 2 ) was recorded by application of Parthenium hysterophorus extract but minimum leaf area (23.76 mm 2 ) was noted from the treatment where distilled water was applied. These results are supported by Oyerinde et al. (2009) who reported that application of aqueous extract of T. diversifolia significantly increased leaf area of maize seedling.

Leaf Chlorophyll content (SPAD)
Effect of foliar application of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale on chlorophyll contents of parthenium was found statistically significant (Table 1). The data indicated that maximum chlorophyll contents (12.06) were recorded when Sisymbrium orientale extract was applied which was statistically at par with chlorophyll contents of parthenium seedling produced by aqueous extract of Adiantum capillus-veneris and Parthenium hysterophorus while control treatment produced minimum (9.77) leaf chlorophyll content. Khaliq et al. (2013) reported that application of aqueous leaf extract of Coronopus didymus decreased the chlorophyll contents of wheat plants.

Electrolyte leakage (%)
A statistically significant impact of foliar spray of aqueous extracts of Adiantum capillusveneris, Parthenium hysterophorus and Sisymbrium orientale on electrolyte leakage of parthenium seedling was observed (Table 1). Results showed that maximum electrolyte leakage (43.53%) of parthenium seedling was noted when aqueous extract of Parthenium hysterophorus was applied while minimum electrolyte leakage (23.76%) was observed in control treatment. These findings are supported by Skrzypek et al. (2015) who observed that electrolyte leakage from sunflower seedling was increased due to the application of aquatic extract of peppermint.   Table 3). The application of Parthenium hysterophorus extract produced Trianthema partulacastrum seedling with maximum leaf area (43.92 mm 2 ) while control treatment and application of Adiantum capillus-veneris extract resulted in minimal leaf area (23.45 and 24.25 mm 2 ) of Trianthema partulacastrum. These results are supported by Oyerinde et al. (2009) who found that application of fresh shoot aqueous extract of Tithona diversifolia significantly increased leaf area of maize plants.

Leaf chlorophyll content
Leaf chlorophyll content of Trianthema partulacastrum seedling was significantly influenced by the application of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale (Table 3). Maximum (28.55) chlorophyll content was observed when distilled water was applied while minimum leaf chlorophyll content (26.90) was observed when Parthenium hysterophorus extract was applied. The results are supported by Khaliq et al. (2012) who reported that foliar spray of wheat straw extract on horse purslane inhibited its seedling growth and chlorophyll contents.

Electrolyte leakage (%)
Foliar spray of water extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale significantly affected the electrolyte leakage of Trianthema partulacastrum (Table 3). Highest electrolyte leakage (43.92 %) was observed when water extract of Parthenium hysterophorus was applied while minimum electrolyte leakage (23.46 %) was noted with control treatment. Our observations are supported by Joanna et al. (2016) who reported that foliar application of aqueous extract of Galium aparine L. increased the electrolyte leakage of Zea mays L. seedlings as compared to control.

Fresh weight (mg)
The foliar application of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale had a non-significant effect on fresh weight of Trianthema partulacastrum seedlings (Table  4). Data showed that the maximum fresh weight (0.16 mg) was observed in those seedlings where distilled water was applied while minimum fresh weight (0.12 mg) was noted with exogeneous application of aqueous extract of Sisymbrium orientale. Our results are similar with the findings of Javaid and Shah (2007) who reported that aqueous leaf extract of Eucalyptus citriodora Hook and Eucalyptus camaldulensis Dehnh caused a non-significant effect on seedling biomass of parthenium plants.

Shoot length (cm)
The foliar application of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale had a significantly effect on shoot length of Trianthema partulacastrum seedlings (Table  4). Among different treatments, the aqueous extract of Parthenium hysterophorus resulted in lowest shoot length (2.05 cm) of Trianthema partulacastrum seedling while maximum shoot length (2.38cm) was found in control treatment. These results are not in accordance with Jiang (2015), who found that the water extract at 60 g/L of onion bulbs decreased the cotton shoot length.

Root length (cm)
Significant effect of foliar spray of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale on root length of Trianthema partulacastrum seedling is presented in table 4. The indicated that maximum root length (2.53 cm) was recorded under control treatment which was statistically similar with aqueous extracts of Adiantum capillus-veneris and Parthenium hysterophorus while minimum root length (2.10 cm) was noted with the foliar application of aqueous extract of Sisymbrium orientale. Our results are supported by Javaid (2009) who observed that application of aqueous extracts of Datura alba and Withania somnifera decreased shoot length (62%), root length (96%) and seedlings weight (68%) of Rumex dentatus. Dry weight (mg) Data regarding the effect of foliar spray of aqueous extracts of Adiantum capillus-veneris, Parthenium hysterophorus and Sisymbrium orientale on dry weight of Trianthema partulacastrum seedling was non-significant (table 4). Maximum dry weight (0.0231 mg) was recorded with the application of distilled water while Sisymbrium orientale extract produced minimum dry weight (0.0084 mg). Our results are supported by Javaid and Shah (2007) who observed a non-significant effect of aqueous extract of Eucalyptus citriodora Hook and Eucalyptus camaldulensis Dehnh on parthenium seedling biomass. and Sisymbrium orientale on seedling growth of two weeds (Parthenium hysterophorus and trianthema partulacaastrum). The data of our experiment lead to conclude that S. orientale extract have comparatively more active substances with ability to suppress germination and growth of weeds which could be exploited as prospective source of bioherbicides. Further field based research is needed to investigate the effect of abiotic and biotic factors on the allelopathic potential of S. orientale.