Short communicationMaximizing oilseed rape's yield by glyphosate under Mediterranean conditions

Adverse hot and dry environmental conditions prevailing during the period of oilseed rape ripening can be blamed for considerable yield losses during the crop's mechanized harvesting in the Mediterranean area. In this paper, the effect of chemical dessication of oilseed rape with glyphosate applied 35 days after anthesis for reducing seed yield loss was studied. The experiment was conducted in four fields at two locations in central Greece and for two growth periods following a completely randomized plot design with 8 treatments in three replications. Treatments include all possible combinations of two crop varieties and four levels of glyphosate (as dessicant) application. A significant positive effect of dessicant application level on crop yield for both studied varieties was found. The application dose of 200 g a.i. of glyphosate per hectare had the best results. The highest dry weight was found among the plants sprayed with 200 g. a.i. of glyphosate per hectare. The highest seed yield and oil yield were found among the plants sprayed with 200 g a.i. per hectare, which makes clear the positive effect of this spraying minimizing pod shattering and yield losses. The greatest 1000-seed weight was found among the plants sprayed with 200 g a.i. ha−1, due to the greater size of seeds that remained on the plants until harvesting.

Research highlights▶ The use of glyphosate as dessicant at an early stage of oilseed rape's growth and at rates far less than those suggested when it is used as a herbicide, resulted in significant gain in oilseed rape's yield, dry matter and also in the 1000-seed weight. ▶ This indicates the ability of glyphosate's application in strengthening the pod and therefore making it hold more seeds and especially the heaviest of them which in turn can afford us with greater oil yield, as suggested in this work, without any significant result on oil content which is severely regulated by genetic factors.