One of the main objectives of the contemporary phytotecnics is the increase of the vegetal productionquantity with out diminishing its quality. It canbereached bycreatingsowings withanoptimal and durable assimilation surface which would contribute to the photosynthetic efficiency increase. Theresults of the investigations heldin 2006-2007 proved that the morphological parameters,leaves mass and foliar surface could be a characteristic of the phenotype, but they can’t give an information about its productivity. The researches of the phosynthetic parameters during the vegetation offer a piece of information about the physiological state of the plants, which allows to elaborate an optimal regime of cultivation. The studied varieties Odeskaia 267 and Select used the light energy more efficiently after the precursor vetch with the sowing density of 6-7 mln viable seeds per hectare.