IMPACTS OF SOIL SOLARIZATION COMBINED WITH OTHER WEED CONTROL STRATEGIES ON WEED MANAGEMENT IN ONION NURSERIES

A field experiment was conducted at The University of Agriculture Peshawar- Pakistan, during September - October 2010, to determine the effects of soil solarization in combination with different weed control strategies on weed management in onion nurseries. The experiment was laid out in Randomized Complete Block Design and each treatment being replicated three times. Factor A (solarization vs. non-solarization) assigned to main plots while factor B (various other weed control strategies) allotted to sub-plots. The solarized plot was covered with a transparent plastic sheet for 20 days. After removal of the sheets, the plot was ploughed. Seed of onion cultivar (Swat-1) were broadcasted on flat beds at the rate of 20 g m^-2 after a seed germination test. After sowing the seed, a light watering was performed through a garden jerry can and later on the beds were watered as per requirement. The main plot was divided into 16 sub-plots (each 1 m^2). After removal of plastic sheet sedges and grassy weeds were found in abundance as compared to broad leaf weeds. Plastic sheets encouraged weed germination, because during the particular time of the year (25th Sept. -15th Oct.) the heat produced and the moistures conserved by plastic mulches favoured weed seeds germination. And as a result weeds infestation was more in the solarized plot than the non solarized plot. Stomp 330 EC and Parthenium hysterophorus L. mulch controlled weeds but also affected onion seedlings growth adversely. Grass clippings as mulch boosted the growth of the broad leaf weeds particularly of the curly dock. Isoprotoron effectively controlled Cyperus rotundus L., Coronopus didymus L., Fumaria indica L., and Cirsium arvense L. but did not control Cynodon dactylon L. and Convolvulus arvensis L.