Effect of burial depth and cultural practices on nutlets emergence and viability of cyperus Rotundus L. under up land conditions in the dry zone, Sri Lanka

Abstract

Cyperus rotundus known a,s purple nutsedge is identified as one of the problem weeds. The underground nutlets in the soil bank are the propagules. Vigorous nutlets are capable of emerging from deep soil profile of 30 cm. The nutlets buried in the top 0-15 cm layer loose its viability quickly than the nutlets buried in deeper layer of 15-30 cm. Continuous land preparation helped to bring the nutlets to the upper surface where they were desiccated due to high temperature and loose viability. Nutlet viability in the upper layer of 0-15 cm reduced from 82% to 2% in 105 days due to continuous land preparation. The same land preparation reduced the nutlet viability from 88% to 14% in the deeper layer of 15-30 cm in 105 days. Continuous mulching for four months with palmyrah leaf reduced the nutlet viability from 80% to 10% in the upper layer of 0-15 cm and 86% to 26% in the lower layer of 15%-SO%. Mulching with black polythene was found to be better than palmyrah leaf in reducing the nutlet viability. It reduced the viability from 80% to 6% in upper layer and 86% to 9% in lower layer in four months time.