Agronomic performance of different pea cultivars under various sowing periods and contrasting soil structures

Yield variability of spring pea (Pisum sativum L.) in farmers' fields is mainly due to soil compaction at sowing and abiotic stresses during the reproductive period. Winter peas flower earlier, and thus should be less sensitive to abiotic stress at the end of the cycle, but because of their sensitivity to frost they must be sown late in autumn when soils are very wet. Pea breeders are working on new winter cultivars that are more resistant to frost and highly sensitive to photoperiod and that could be sown earlier in autumn under better soil conditions. Our aim was to measure crop growth, development, and seed yield of different types of pea cultivars using factorial experiments that evaluated the effect of soil structure, sowing period, and cultivar at two sites in France. Compaction reduced seed yield by 18% at Grignon and 6% at Estrees-Mons, but had no significant effect on crop development. November sowings resulted in increased seed yield of about 1 t ha(-1) at both sites compared with spring sowings, and were associated with larger numbers of reproductive nodes and seeds m(-2). Cultivars exhibited contrasting characteristics in terms of mean seed dry weight, seeds m(-2), and number of reproductive nodes, but final seed yields were similar within sowing periods. The ability of the crop to convert crop growth rate to seed number was independent of environment but decreased linearly with mean seed dry weight of the cultivar. This research suggests that pea breeders should develop new winter pea cultivars with earlier flowering to enhance yield.