23. Studies on some biological features of tuberous sour grass Cyperus rotundus L.

In the period 2010–2013 in the region of Serres, Greece a field experiment was carried out with cotton the Carmen variety, including 8 variants weeded with tuberous sour grass Cyperus rotundus L. 0, 1, 2, 4, 8, 16, 32, 64 pcs./m². The experiment was set by the block method in four replications with the size of the testing plot – 1 m².
It was found that the fresh weight of Cyperus rotundus L., an average of 10 stems ranged from 200 to 387 g, the dry weight – from 95 to 192 g, the height of the stems – from 31 to 47 cm, and the number of generated weed seeds from one plant was from 780 to 1,497 units depending on the degree of weed infestation.
The decrease of those indicators was particularly well expressed at reaching and overpassing the 32 pc./m² density of weed infestation with Cyperus rotundus L. The high density degree of Cyperus rotundus L. caused a delay in the onset of flowering and ripening stages of cotton, which in turn adversely affected the formation of the quantity and quality of the yield.