M. Gerdgikova, M. Videva, D. Pavlov

Abstract. The effect of cultivating two predecessor varieties: (i) wheat and (ii) Triticale, on the content and yield of crude protein from winter pea variety “Mir” is tested during 2005-2007. The study is conducted at Trakia University, Stara Zagora, in conditions of organic and conventional production. It is found that both pea grain yield and crude protein yield are higher using conventional farming and after predecessor wheat. Higher pea grain yield is obtained using conventional cultivation method and after predecessor wheat. Crude protein content of winter pea grain is higher after predecessor triticale. The protein concentration in pea grain correlates with rainfall during the growing season and the critical months February, April and June, and can be modeled by regression equations. The protein yield can also be modeled by regression equations based on the amount of precipitation during vegetation and the aforementioned critical months. The determination coefficient, R2, is higher for protein content, R2 = 0.958, compared to that for protein yield, R2=0.606.