Optimum plant densities for three semi‐leafless combining pea (Pisum sativum) cultivars under contrasting field conditions

SUMMARY Yield and yield components of three semi‐leafless pea (Pisum sativum) cultivars, of contrasting seed type/growth habit, were assessed at target planting densities of 40–140 plants/m2 on nine sites over three years. Flat‐topped parabolic/asymptotic yield/density relationships were obtained. The plant density required to maximise (p max) and optimise (p opt) yield differed between cultivars: Helka, small blue, p max 126 plants/m2, p opt 101 plants/m2; Solara, large blue, p max 124 plants/m2, p opt 94 plants/m2; and Countess, white‐seeded, p max 104 plants/m2, p opt 71 plants/m2. Near‐maximum yields were maintained between 70 and 140 plants/m2 due to the ability of the pea crop to make compensatory increases in the number of pods per plant as density declined. Yield/density responses were influenced by site (e.g. soil type) more than by seasonal factors. The risk of yield reductions occurring at densities below 70 plants/m2 was greater on a mineral soil than on a fertile organic soil. On the basis of agronomic and economic considerations, there was no evidence that target plant densities required to optimise yield should necessarily be higher for semi‐leafless cultivars studied than for conventional leafed peas.