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Parthenium hysterophorus. L; competitive index; Grasses Suppression and management option

Parthenium hysterophorus L. is one of the worst weeds of the world which has got a position among the list of top ten worst weeds of the world and has been listed in the global invasive species database.

In areas where the weed occurs, the productivity of forage is reduced by 90% and the weed make lands infertile and weakens the quality of grazing land, animal health, meat and milk products, agricultural production [1]. Parthenium exerts strong allelopathic effect and reduces the growth and reproduction of associated crops. It does these by releasing phytotoxins from its decomposing biomass and root exudates in soil [2].

In Queensland, cattle production has declined by approximately 4.75 animals due to this weed [3] with an associated financial loss of Aus $16.5 million per annum.

Despite, various methods have been used to manage parthenium weed worldwide but most have limited effect, or need to be re-applied constantly on an annual basis as and when the weed re-emerges from the soil seed bank. [4] Discussed the constant need to reapply herbicides following seasonal re-emergence of parthenium weed in sorghum (Sorghum bicolour L.) crops. These observations have suggested that supplementary, site-specific management strategies are now required to achieve superior management of this weed.

In areas where it is possible, the displacement of this weed with beneficial plants is considered to be an ideal management approach. Previously, in a glasshouse experiment, floren bluegrass (Dichanthium aristatum Poir.), bisset bluegrass (Bothriochloa insculpta cv. Bisset) and buffel grass (Cenchrus ciliaris L.) were all shown to be able to displace parthenium weed [5] and to produce a quantity of fodder biomass at an appropriate level to sustain livestock production. Moreover For example in India, guinea grass (Panicum maximum Jacq.), tannre’s cassia (Cassia auriculata L.) and fedogoso (Cassia occidentalis L.) [6] Have been used; in Ethiopia, sorghum (Sorghum bicolor L.) Moench, and in South Africa, African love grass (Eragrostis curvula Nox.) have all shown significant suppressive effects upon the growth of P. hysterophorusL.in the field. The sowing of suppressive plants has been shown to be effective in improving the management of the weed in several countries. However, in Ethiopia there no and/or no research has been done about the suppressive effect of grasses against parthenium. Therefore, the objective of this research was to evaluate the suppressive effect of different grasses sown at different combination on the growth and development of P. hysterophorus L.

Description of experimental site

The experiment was conducted in Ambo University Guder Campus which found in Toke kutaye district. The area is 8058’ N located 37co 46’E with about 125km western of Addis Ababa with temperature 8.25- 23.40c. Altitude 2101m.a.s.l and rain fall is 800-1100mm.

Treatment and Experimental Design

Pot experiment comprised of three grasses (Cenchru sciliaris L. Panicum maxicum Jacq and Pennisetum perpureum) sown different replacement series with parthenium hysterophorus L. (0:4, 3:1, 2:2, 1:3, 4:0) were undertaken. The experiment was arranged CBD (Complete Block Design) with three (3) replication.

Cultural Practices

The seeds of selected grasses were collected from ILIRI Ethiopia. Seeds of all species were sown into cell trays filled. The cell trays containing the seeds were then kept in an open air and watered to field capacity. Soil from upper surface; sand, compost and top soil was collected and sieved by using 2mm diameter of sieve. Composited soil was prepared with proportion of 2:1:1 of soil, sand and compost ratio respectively and pots (25 cm diameter) were filled this soil (air dried). The soil was then watered to saturation and allowed to drain for 24 h to reach a soil moisture content that was close to field capacity. The 10-day-old seedlings of parthenium weed and the test plant species were then transplanted into these pots as par the treatment proportion and watered to field capacity and allowed to grow together for 90 days. An replacement series experimental design was used in which seedlings were sown to a total density of 4 plants pot-1(representing 80 plants per m-2), each at five combinations of parthenium weed-to-test plant species (viz. 4:0, 3:1, 2:2, 1:3, 0:4) each replicated three times. Watering was done twice a day at the morning and afternoon by using water cane.

Data Collection

plant height was recorded from ground to the tip of the plant using ruler, number of branches per plant was counted and their average was computed, fresh biomass was recorded after harvested and dry biomass weight was taken by oven drying the fresh weight at 650c until constant weight, Ability with stand competition of grasses (AWC) was determined using

Data Collection

All the collected data was subjected to analysis of variance following (CBD) procedure using SAS and mea separation was conducted for treatment means using least significance differences (LSD) at 5% probability level.

Plant height

According the data presented in (Table 1) showed that effect of different sowing mixture of grasses was significantly reduced the height of Parthenium hysterophorus L. the shortest height (7.67cm) of P. hysterophorus L. was recorded from 75:25 (Panicum maxicum Jacq: P. hysterophorus L.) sowing combination followed by 75:25 (Cenchrus ciliaris L.:P.hysterophorus L.)(11.33 cm) followed by 50:50 (Panicum maxicum Jacq: P. hysterophorus L.) however non significance difference was observed among them whereas, the tallest (74.67cm) was recorded when P. hysterophorus L. allowed to grown alone (100:0). Interestingly as the sowing proportion of grasses were increased from 25:75 (grass: P. hysterophorus L.) to 75:25 (grass: P. hysterophorus L.), the height of the P. hysterophorus L. was significantly decreased. This height reduction may be due to sowing proportion and long period of interferences of grasses against the P. hysterophorus L.

Table 1: Test grasses description

Leaf Number

From the data showed in P. hysterophorus L. leaves per plant was significantly affected by the sowing proportion. The maximum number leaves per plant (70.67) was observed from 100:0 (P. hysterophorus L.: grasses) sowing combination whereas minimum number (9.0) when P. hysterophorus L. grown with Panicum maxicum Jacq at 75:25 (grasses: P.hysterophorus L) sowing mixture. This may be due the suppressive effect of the fodder grasses and their higher sowing proportion on the leave production of P. hysterophorus L. These results are in accordance with the work of who documented that growth features of some fodder plants (rapid root growth and greater shoot biomass accumulation) are also responsible for their ability to suppress the growth of P. hysterophorus L.

Branch Number

Like plant height and leaves number per plant, branch number of P. hysterophorus L. was also significantly affected by different sowing proportion. As the data presented in indicated that maximum number of branches per plant (22.3) was produced when P. hysterophorus L. was grown alone whereas the minimum number of branches per plant (6.8) was recoded from 75:25 (Panicum maxicum Jacq: P. hysterophorus L.) followed by 75:25 (Cenchrus ciliaris L.: P. hysterophorus L.) (8.7) and 75:25(Pennisetum perpureum: P.hysterophorus L.) sowing proportion however no significance difference was observed among them. This may be due the significant reduction of plant height and leaf number P. hysterophorus L. by these fodder grasses in all sowing proportion as compare to the sole grown weed.

Fresh biomass

As the data pertained in showed that the effect of different sowing mixture of fodder grasses were significantly reduced the fresh biomass of P. hysterophorusL. The highest fresh biomass per plant (84.4 g/plant) was obtained at 100:0 (P. hysterophorus L: grasses) sowing proportion whereas the lowest (23.1 g/plant) was recorded from 75:25 (Panicum maxicum Jacq: P. hysterophorus L.)

Dry biomass

Dry biomass production of P. hysterophorus L. was also significantly reduced by sowing proportion of grasses. The minimum dry biomass (10.9 g/plant) was produced at 75:25 (Panicum maxicum Jacq: P. hysterophorus L.) followed by 75:25 (Pennisetum perpureum: P. hysterophorus L.) (12.4g/plant) and 75:25(Cenchrus ciliaris L.:P. hysterophorus L.) (13.6g/plant) sowing proportion however, no significance difference was observed among them.

Relative crowding coefficient

The relative crowding coefficients based on aboveground biomass suggested that Panicum maxicum was more dominant than parthenium in plant mixture of 75:25 (Panicum: Parthenium). In this combination, P. maxicum had higher crowding coefficients. However, as shown in 25:75, combinations parthenium was more dominant as indicated by higher crowding coefficients. The study showed that the biomass of parthenium was strongly inhibited by the presence of Panicum maxicum in 75:25 followed by Pennisetum perpureum 75:25 and Panicum maxicum 50:50seed proportion.

Aggressivity index of grasses

According to this study, the biomass of these species was strongly reduced when two species (parthenium and any grass) exist together.

The reason might be due to allelopathic interaction (which is not determined) that exists between the two species. This finding was in accordance with the work of who stated that C. ciliaris and B. insculpta strongly outcompeted parthenium hysterophorus L.

Competitive index

Based the data indicated in showed that as the proportion of grasses increased the competitive index was increased. Panicum maxicum, Pennisetum perpureum sown in 75:25 and 50:50combination (grasses: Parthenium) showed higher competitive index (> 1.5) followed by C. ciliaris which were strong competitive against parthenium. Moreover Panicum maxicum sown in 25:75 and C. ciliaris sown in 50:50 proportions results moderate (1-1.5) competitive ability against the parthenium weed. These may be due to features of faster growth or interference may be the characteristics of these species that makes them useful for the displacement of parthenium weed. Similar result was also obtained who found competitive index greater than 1.5 for Panicum maxicum and C. ciliaris.

Ability with stand competition of grasses (AWC)

Ass the data presented in indicated that the ability to withstand competition against parthenium was significant at different density of sowing. As can be seen the greatest ability to withstand competitive (151.30) was obtained from P. maximum Jacq+Parthenium at 75:25 sowing mixture which is not statistically differ from P. perpureum+Parthenium (139.19) at the same sowing mixture whereas the lowest was recorded from C. ciliaris L. +Parthenium (42.56)at 25:75 sowing mixture. As the density of grasses increased the ability of the fodder grasses to withstand competition was also increased which indicates that keeping the grasses at higher density or reducing the grazing frequency could be option for management of parthenium in rangelands and pasture lands.

From this experiment it can be concluded that Sowing of Cenchrus ciliaris L., Pennisetum perpureum, Panicum maximum Jacq at different sowing density significantly suppressed plants in infested areas can suppress the growth and development of parthenium weed and provide improved fodder for stock. Keeping the grasses at higher density or reducing the grazing frequency could be option for management of parthenium in rangelands and pasture lands. However these results were obtained under non-grazing conditions and undertaken using just a single species in a plot. It is anticipated that to gain the best parthenium weed growth suppression, mixes of suppressive plants should be used and, hence future work should focus on the use of sowing mixes under grazing pressure. High percentage of the respondents experienced improvement after using Colgate Sensitive Pro-RelifTM toothpaste, after a maximum of two weeks, and at least after the third week.

The author thanks to Ambo University for their financial support to conduct this study.