Influence of Timing of Herbicide Application on Winter Canola Performance
Canola (Brassica napus L.) is an important source of vegetable oil for humans and canola cake is a nutritious feed for animals. However, weeds are one of the major constraints in canola production in the southeastern regions of the United States causing loss upto 50 percent in yield. Control of weeds in spring canola has been reported but research on weed control in winter canola has not been well documented. Therefore, research experiments were conducted from 2005 to 2007 to evaluate the effects of herbicide application timings on canola performance. Results showed that pre-emergence timing of trifluralin @ 1 kg ai ha resulted 496 kg ha , 411 kg ha , 502 kg ha higher canola yield as compared to control in 2005, 1 1 1 1 2006 and 2007, respectively. Pre-emergence application timing of trifluralin gave 79% less weed biomass than control plots. Increasing weed density and weed biomass significantly reduced the canola yield whereas increasing plant height increased the canola yield significantly. This study revealed that herbicide application timing significantly reduced weed biomass and increased canola yield.
Integrated Weed Management in Indian Mustard
One hand weeding supplemented with thiozypyr at 120 or 150 g ha−1 being statistically at par with two hand weedings (20 and 40 DAS) reduced the dry weight of weeds to the extent of 90% and resulted in seed yield of mustard statistically equivalent to weed-free plots. Chlorimuron caused 92–98% crop injury. Weeds growing throughout the crop season resulted in 24.7% reduction in seed yield of mustard.
Geomagnetic Polarity Epochs: Sierra Nevada Data, 3
Available paleomagnetic and radiometric results for about 60 igneous rocks 3.6 m.y. old or less are consistent with the following geomagnetic polarity epoch time scale: Brunhes normal polarity epoch, 0.0 to 0.85±0.15 million years; Matuyama reversed polarity epoch, 0.85±0.15 to 2.4±0.1 million years; Gauss normal polarity epoch, 2.4±0.1 to 3.35±0.1 million years; Gilbert reversed polarity epoch, 3.35±0.1 million years to (?). A brief interval of normal polarity (the Olduvai event) occurs within the Matuyama reversed epoch at about 1.9 m.y., and a brief interval of reversed polarity (the Mammoth event) occurs within the Gauss normal epoch at about 3.06 m.y. Data for twelve units from eastern California and Nevada, reported here for the first time, are particularly useful in defining the Gauss-Gilbert boundary and for recognizing the Mammoth event.