Interaction Between Cereals and Pea Intercrops During Their Initial Development

The species that make up the intercrop interact with each other during their development, which can be beneficial, harmful, or indifferent to the participants. The aim of this study was to determine whether the developmental differences observed between intercropped and pure stands are already evident at early developmental stages. We conducted three experiments: (1) a laboratory germination test using filter paper rolls, (2) a laboratory growth test in plant pots, and (3) a small-plot field experiment comparing the development of mixtures and monocultures of winter cereals (winter wheat, winter durum wheat, winter einkorn, winter triticale, winter barley, and winter oats) and winter peas. Based on our results, only minor differences were observed (1–3%) in germination parameters (germination percentage, germination vigor, and seedling health). However, as plant development progressed, increasingly pronounced differences emerged (significance level of p < 0.05) between intercropped and pure stands based on which we assume allelopathic effects. Winter wheat and durum wheat had a positive effect on the initial development of winter pea, whereas barley, and oat had a clearly negative effect. Winter pea negatively affected the germination and early development of triticale and oat, while it had a positive effect on the initial development of durum wheat. Mutually beneficial interactions were identified in the winter wheat–pea and durum wheat–pea combinations during the early stages of plant association.