PJB-2017-799
Estimation of Critical Period of Exotic Invasive Weed Alternanthera philoxeroides Interference in Maize
Muhammad Nadeem
Abstract
Alternanthera philoxeroides, a quickly spreading troublesome invasive weed of summer crops is causing substantial yield losses in maize and other crops. Influence of A. philoxeroides at different weed free (full season, 3, 4, 5 and 6 weeks after crop emergence (WAE) and weedy periods (full season, 3, 4, 5 and 6 WAE) on maize was estimated during two consecutive years (2013 and 2014). The increasing weed competition period caused significant increase in weed dry weight (up to 646%) and nutrient uptake (876-1377%). Weed competition caused reduction in maize plant height (14%), grain weight (22%), number of grains (31%) and grain weight per cob (30%). Different A. philoxeroides competition periods caused up to 37% and 45% biological and grain yield losses of maize, respectively. Relative weed competitive index range was 3.14-45.10%. Four parameter logistic model predicted 0.26-6.04 WAE and 0.35-5.86 WAE as critical period of competition for A. philoxeroides in maize to avoid 5% to 10% maize grain yield losses, respectively. The comparatively narrow window for competition period might be due to its fast and prostrate growth habit, high nutrient uptake and strong allelopathic potential. Appropriate management strategies would help to condense anticipated spread of A. philoxeroides and maize yield losses.
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