Effects of single and combined fertilization of selenium and cobalt on growth and yield of alfalfa

A experiment was conducted to study the effects of selenium(Se)and cobalt(Co)on the growth, yield and quality of alfalfa(Medicago sativa L.)in the yellow river beach of Henan. The results show that the rational single and combined applications of Se and Co could promote net photosythetic efficiency, decrease plant respiration loss, enhance production rate of dry matter from ramification to florescence, and raise alfalfa hay production from the ramification to the florescence stages of alfalfa. The application rates of Se being 570 g/ha and Co 765 g/ha combined application have the best effects on the forage production and grain development, and alfalfa hay is increased by 8.06 % and 1000-grain weight is increased by 12.85 %. The Co or Se and Co combined application could also promote growth of root nodule and accumulation of root nodule volumes of alfalfa in a depth of 0-20 cm which could enhance nitrogen fixation. In conclusion, rational basal applications of Se and Co have better effects on fine hay and seed production because they could enhance net photosynthetic capacity, promote growth of alfalfa, raise yields of alfalfa and improve seed quality.