Effect of weed management on sisal (Agave sisalana) nursery

Abstract

A field experiment was conducted during June–December of 2009 and 2010 at Bamra, Sambalpur, Odisha, to study the effects of weed-management methods on the weeds of sisal (Agave sisalana Perrine ex Engelm.) nursery and their effect on the growth of sisal plants in nursery and also on soil microbes. The dominant grass weeds were Cynodon dactylon (L.) Pers., Eleusine indica (L.) Gaertn., Dactyloctenium aegyptium (L.) P. Beauv., and Digitaria sangunalis (L.) Scop. The important broad-leaf weeds were Solanum nigrum L., Amaranthus spinosus L., Physalis minima L. and Phyllanthus niruri L. The only sedge weed was Cyperus rotundus L. in the experimental plots. At 15 days after planting (DAP), the highest weed-control efficiency (WCE) of 89.2% was recorded with smetolachlor and at 30 DAP, the highest WCE was obtained from manual weeding (90–93%), followed by smetolachlor (87.1%). However, at 45 DAP and beyond only 2 manual weeding showed the highest WEC of 92.3 (45 DAP) and 71.8% (60 DAP). Hand-weeding twice produced the most robust type of sisal plantlets (13.9 g/plant), followed by sisal waste (13.3 g/plant). All the tested herbicides reduced the biomass production by sisal bulbils as compared to hand weeding in the order of trifluralin (14.7%) > pretilachlor (22.1%) > s-metolachlor (35.9%) > quizalofop ethyl (39.2%). At the maturity stage of sisal bulbils in the primary nursery, there was little effect of trifluralin and quizalofop ethyl on the total bacteria count. In contrast, the total bacteria population remained depressed in pretilachlor (41.7%) and s-metolachor (42.1%)-treated plots. The total actinomycetes population could not reach to the normal level (57.79 × 104 CFU/g) in case of s-metolachlor (–50.2%), pretilachlor (–46.1%) and quizalofop ethyl (–38.6%). At this stage, the total fungi population was more or less same in all the treatments except in quizalofop ethyl which increased the population by 2.5 folds.