EVOLUTION AND RELATIONSHIP OF SOME MACRO MINERALS IN Medicago sativa L. PLANTS

Research conducted between 2013-2014, at Ezăreni Farm, Iaşi (47°05' 47°10' north latitude and 27°28' 27°33' east longitude) investigated at alfalfa (Medicago sativa L.), in the second, third, fourth and fifth vegetation year at the first cut, the influence of alfalfa plant phenophase at harvest on plant production of leaves, stems and whole plant (DM dry matter) per hectare and leaves, stems and whole plant N (nitrogen), P (phosphorus), Ca (calcium) and Mg (magnesium) content. The experiment was laid by randomized block method in three replicates. Graduations of the studied factor were represented by the development phenophases: early bud, mid bud, late bud; early bloom, 10% bloom and full bloom. The results showed that the total production of DM was between 3.20 Mg·ha -1 (control variant) and 4.73 Mg·ha -1 (full bloom variant). At a more detailed analysis of interdependencies between mineral elements studied were highlighted some important ideas. Thus, from mineral elements studied in whole plants, between Ca and P there is the slightest interdependent relationship. The relationships N-P/P-N (R 2 =0.739-0.841) and N-Mg/Mg-N (R 2 =0.613-0.661) are positive, and the relationship Mg-Ca/Ca-Mg (R 2 =0.576-0.653) is negative. The results can be useful to improve alfalfa fertilization system and to balance the Ca/P ratio from alfalfa plants.