In sustainable and organic farming methods, great importance is attached to environmentally friendly components of crop production techniques, particularly the preceding crop. This study has assessed the effects of four preceding crops, i.e. field pea, winter oilseed rape, spring barley and wheat (or spelt), on gas exchange parameters, foliage, grain yield and N uptake in common wheat and spelt. The study was based on a field experiment carried out in north-eastern Poland. The experimental factors were as follows: 1. winter wheat subspecies: common wheat and spelt; 2. cultivation of the above-mentioned cereals in stands after field pea, winter oilseed rape, spring barley and one after the other. A favourable effect of oilseed rape as a preceding crop on the activity of the stomatal apparatus and the assimilation and transpiration rates was demonstrated. In the stands after cereals, wheat and spelt assimilated less CO2 than after the other preceding crops. However, the intercellular CO2 concentration value after these crops was higher than after pea and oilseed rape. Wheat used water more efficiently during photosynthesis in fields after pea and oilseed rape than after cereals. In spelt, the preceding crop had no significant effect on this parameter. The surface of leaves and their chlorophyll content (SPAD) in wheat and spelt in stands after pea and oilseed rape were greater than after barley and wheat (or spelt). Oilseed rape as a preceding crop had a favourable effect on grain yield in both cereals. Wheat and spelt responded negatively to the cultivation of one after the other by a decrease in grain yield, with the decrease being greater in spelt than in wheat. In both cereals cultivated after all forecrops, a significant relationship was demonstrated between assimilation and the aperture, transpiration, chlorophyll content of leaves, grain yield and N uptake. The preceding crop differentiated most gas exchange parameters more in wheat than in spelt.  

25.2.2020