THE EFFECT OF BIOSTIMULANT ON YIELDS OF MIXED GRASS/RED CLOVER STANDS AND CHLOROPHYLL CONTENT IN CROP PLANT LEAVES UNDER DIFFERENT NITROGEN FERTILISATION REGIMES

摘要

The objective of the study was to determine the effect of the biostimulant Kelpak at different nitrogen concentration on the yields and chlorophyll content of mixed grass and Trifolium pratense stands. Field experiment was organized as a randomised sub-block design (split-split-plot) with three replicates. The experimental factors were: the biostimulant Kelpak SL applied prior to each of three cuttings as a spray at a rate of 2000 dm~3 ha~(-1) and a control - no biostimulant; nitrogen rate with concentration of 50, 100 and 150 kg ha~(-1) and a control (0 kg N~- ha~(-1)); four grass/Trifolium pratense mixtures. The experiment was carried out to determine yields and chlorophyll content of the grass-legume mixtures of leaves (SPAD value) within 2010-2012. Application of Kelpak significantly increased the yields and chlorophyll content of mixed grass-legume stands. More higher dry matter yields were harvested from nitrogen-fertilised plots compared with non fertilised plots. Increasing of nitrogen rates significantly increased the chlorophyll content of grasses and Trifolium pratense. The highest yields were recorded for the Dactylis glomer-atalTrifolium pratense mixture irrespective of the nitrogen rates and biostimulant variants. The highest yields were also determined when spraying Kelpak with nitrogen fertilisation at a rate of 150 kg ha~(-1).