Zimbabwe Open University, Department of Agriculture Management, Bindura, Zimbabwe

Sorghum arundinaceum Desv Stapf (wild sorghum) is spreading rapidly in Zimbabwe’s farming communities. An experiment was carried out at Bindura University of Science Education to assess the plasticity ofwild sorghum in response to 25%, 50%, 75% and 100% field capacity (FC) watering regimes in different soils. The experiment was laid out in a complete randomised design (CRD) with three replications. Soil samples were sieved and thoroughly mixed before pot filling. Plant height was measured using a meter rule, and leaf number and tiller numbers were physically counted at two weeks’ intervals. Dry matter was measured at the end of the experiment using the oven dry matter determination method. Clay soils gave significantly higher (P<0.05) emergence percentage of 76.7% whilst sand soil had the least emergence percentage of 60.8%. Shortest plants of 34.67cm with three leaves and three tillers were observed in 25% field capacity watering regime and the tallest (42.64cm) plants with four leaves and three tillers were observed in 100% field capacity watering regime at 12 weeks after crop emergence (WACE). Loam soil gave significantly (P<0.05) taller plants (40.35cm) but had statistically similar number of leaves and tillers with those in sand and clay soil. The mean dry weight of the aboveground parts was 9.40g and was significantly higher (P<0.05) at 100% field capacity whereas 25% field capacity gave significantly lower (P<0.05) dry weight of 2.74g. Loam soil gave significantly higher dry weight of the above ground parts (P<0.05) of 7.55g whilst sand soil had significantly lower dry weight of 4.78g. The dry weight of roots gave a rather different trend, showing significantly higher dry weight of the roots in 75% FC with 16.69g whereas least dry weight of 11.05g was observed in 25% FC. Clay soil gave the least dry weight of roots of 11.04g whilst the highest dry weight was observed in loam soil with 18.57g. In conclusion, morphological plasticity was depicted in wild sorghum in varying watering regimes and different soil types. Farmers are encouraged to subdue the spread and establishment of wild sorghum in their cropping fields.