Effect Of Rapeseed Residue Remaining On The Soil Surface On Non-Chemical Invasive Plants Management In Subsequent Crop Rotations
Changes in the weed seed-bank due to crop production practices are an important determinant of subsequent weed
problems. Bio-herbicides can play a major role in non-chemical controlling strategies of invasive plants in fields. Rapeseed
(Brassica napus) is cultivated as a spring crop in Iran and redroot pigweed (Amaranthus retroflexus L.) grows along with
different field crops, and is a main factor in yield loss of summer crops.In order to study allelopatic effect of rapeseed
residue on germination and growth of redroot pigweed an experiment was conducted in laboratory and greenhouse. Studied
factors were water extract of above-ground, root and total parts of rapeseed (included distilled water as control) harvested at
three growth stages included early stem elongation, blooming and ripening. Results indicated that when the weed seeds were
irrigated with aqueous extract of above-ground, root and total parts of rapeseed, its germination rate with reducing value of
15%, 34% and 22% ranged from 4 germination per day to 3.4, 2.6 and 3.1, respectively, as compared with control. Rapeseed
harvesting at blooming and ripening stages could reduce germination rate and seedling dry weightof pigweed up to 39% and
21%, respectively, in comparison with control. Pigweed seedling vigor index was 6.5% lower than control, when seeds
treated with root extract harvested at ripening stage. It is concluded that remaining of rapeseed residue on the soil as a
bioherbicide may decrease herbicide use and negative effect of pigweed in summer plants. These kinds of studies clearly
show guidelines for biotechnologists in synthesis of natural herbicides.
Keywords- Bio-Herbicide, Biotechnology, Rapeseed Residue, Redroot Pigweed.