Competition and management Studies of Parthenium hysterophorus L. in forage sorghum

Abstract

A series of experiments were carried out during two consecutive years (2013-2014) at Agronomic Research Area, University of Agriculture, Faisalabad on the interference of Parthenium hysterophorus weed and its management in forage sorghum. The effect of different weed density (0, 2, 4, 6, 8, 10, 12, 14, 16 plants m-2), competition periods (4, 5, 6, 7, 8 weeks after emergence and full season competition) and different Parthenium hysterophorus management techniques (weedy check, hoeing after 3 weeks of emergence, dicamba 100 % dose, dicamba 100 % dose with 1 % ammonium sulphate, dicamba 100 % dose with 2 % ammonium sulphate, dicamba 75 % dose with 1 % ammonium sulphate, dicamba 75 % dose with 2 % ammonium sulphate) on Parthenium hysterophorus fresh and dry weight, NPK uptake by Parthenium hysterophorus, forage sorghum yield, yield components and forage quality was studied in separate experiments under field conditions. Results showed that fresh and dry weight of Parthenium hysterophorus and NPK uptake of Parthenium hysterophorus weed increased with increased in Parthenium hysterophorus weed density and competition duration periods and maximum values for these parameters were recorded at density of 16 plants m-2 and at full season competition period. Yield and yield components of forage sorghum (plant height, stem diameter, no. of leaves per plant, leaf area per plant, leaf to stem ratio, green forage yield and dry matter yield) were reduced with increased Parthenium hysterophorus weed density from 2-16 plants m-2 and with extending the competition periods from 4 weeks to full season competition. Reduction in green forage yield 0.61% - 24.97 % in 2013 and 1.02 % - 26.44 % in 2014 was observed when Parthenium hysterophorus density increased from 2-16 plants m-2 and 2.43 %- 17.71 % reduction in yield occurred with extending the competition periods from 4 weeks to full season competition. The suggested economic threshold level for Parthenium hysterophorus weed was 1.6 plants m-2 in 2013 and 2.2 plants m-2 in 2014 and 5 weeks after emergence seems to be a critical competition period. The crude protein and ash contents were decreased with increased density of Parthenium hysterophorus and extending the competition periods. Whereas the contents of ADF and NDF increased with increase in Parthenium hysterophorus density and competition periods. EEF (ether extractable fat) contents were not influenced significantly both by density and competition periods. All herbicide treatments dicamba alone or in combination with ammonium sulphate and reduced dose of dicamba in combination with ammonium sulphate improved the weed control efficiency (WCE), yield and yield attributes over the weedy check and hand hoeing practice. Application of dicamba full dose with 2 % xviii ammonium sulphate proved superior with 79.60 % weed controlling efficiency (WCE) followed by application of dicamba full dose with 1 % ammonium sulphate with 73.51 % WCE but both these treatments were statistically similar in affecting yield and yield components (plant height, stem diameter, no. of leaves per plant, leaf area per plant, leaf to stem ratio, green forage yield, dry matter yield) and increase in fresh fodder yield was 26.39 % and 20.48 % due to application of dicamba 100 % dose with 2 % ammonium sulphate and dicamba 100 % dose with 1 % ammonium sulphate, respectively over weedy check treatment. Maximum ash and crude protein contents and minimum ADF and NDF contents were observed with the use of dicamba 100 % dose + 2 % ammonium sulphate while ether extractable fat contents were not influenced significantly by Parthenium hysterophorus management strategies. So it is recommended that Parthenium hysterophorus in forage sorghum must be controlled at density of 2.2 plants m-2 within 5 weeks after emergence with the application of full dose dicamba (304.5 g a.i. ha-1) with 2 % ammonium sulphate as an adjuvant with dicamba.