ESTIMATING YIELD LOSSES AND ECONOMIC THRESHOLD LEVEL OF Parthenium hysterophorus IN FORAGE SORGHUM

ABSTRACT A field trial was conducted for two consecutive years to evaluate the effect of different parthenium densities (0, 2, 4, 6, 8, 10, 12, 14 and 16 plants m-2) on the yield and yield components of forage sorghum along with parthenium economic threshold level. The experiment was laid out during the summer in a randomized complete block design with four replications. Different parthenium densities reduced yield and yield components of forage sorghum, as the parthenium density increased significant decline in yield and yield components. The highest parthenium density (16 plants m-2) reduced plant height by 17.19% and 15.32%, stem diameter by 31.79% and 28.10%, leaf area per plant by 18.88% and 10.16%, leaf to stem ratio by 51.01% and 45.03% and fresh fodder yield by 24.97% and 26.49% throughout 2013 and 2014, respectively. Parthenium relative competitive index (RCI), dry weight and nutrient uptake (NPK) also increased as parthenium density increased. The suggested economic threshold level of parthenium was 2.2 and 1.6 plants m-2 in 2013 and 2014, respectively. Thus, control the parthenium at this density level is suggested for achieving high yield of good quality sorghum fodder.