Influence of weed infestation on morphological parameters of maize (Zea mays L.)

The influence of various ways of regulation in weed infestation of silage maize stands was studied in 1999-2001. Four variants of stands were compared: 1. without weed eradication (check), 2. mechanically weeded throughout the whole vegetation period, 3. mechanically weeded from the beginning of vegetation till the phase of 5th leaf and later on without protection, 4. chemical weeding. The yield of dry mass and morphological characters (height of plants, stem diameter, number of ears per plant etc.) show the substantial negative effect of weed infestation upon the studied parameters. The yield from the check variant reached 8.09 t/ha, from the 2nd variant 13.24 t/ha, from the 3rd variant 11.46 t/ha and from the 4th variant 12.34 t/ha. The decrease of mass in individual parts of plants were observed but their percentage portions were not affected by the level of weed infestation. A high dependence ( = 0.01) between the mass of the whole plant and the ear mass (r = 0.98) was proved. The total number of leaves was not affected by the level of treatment. The results show that the mechanical cultivation of stands at the beginning of vegetation cannot prevent the yield depression cost by weed infestation and the studied parameters cannot reach the level of fully weeded variants.