Effects of seed rates, sowing dates and methods of sowing on autumn-sown field beans (Vicia faba L.)

Abstract

SummaryExperiments harvested in 1984, 1985 and 1986 tested the effects of combinations of three seed rates (12, 24 and 36 seeds sown/m2), with three sowing dates (late September and approximately 28 and 56 days later) and two sowing methods (conventionally drilled and ploughed-in after broadcasting) on field beans grown on Clay-with-Flints soil at Rothamsted.Grain yield was always largest with the earliest sowing, smallest with the latest. The seed rate needed to achieve the largest yields increased with lateness of sowing. For September sowings the smallest seed rate was sufficient in 1984 and 1985 but 24 seeds/m2 were needed in 1986 when the exceptionally severe winter killed many plants. In all years 36 seeds/m2 were needed for the latest sowing date.Ploughing-in the seed gave an average benefit to grain yield, relative to conventional drilling, of 0·3 t/ha but the benefit increased to about 2 t/ha for the latest sowing for the 1986 harvest.The earliest sowing advanced flowering date by 2 weeks relative to the latest but did not affect harvest date. Early sowing did not increase susceptibility to winter kill and only slightly increased the risk of chocolate spot disease (Botrytis fabae Sard.).In all years the largest yields came from combinations of treatments which led to about 35–50 pod-bearing stems per m2 at maturity. The best combinations of treatments gave grain yields of 5·6, 50 and 62 t/ha in the 3 years respectively. These reflect the benefits of correct combinations of agronomic treatments and were probably also the result of good control of pests and pathogens.