Effect of sowing time on coriander performance in a semiarid Mediterranean environment

In semiarid environments, time of sowing is one of the most important factors influencing seed yields. For coriander (Coriandrum sativum L.), the most commonly recommended cropping technique is spring sowing (March-April), since the optimum soil temperature for seed germination ranges between 20 and 23 degrees C, and the crop shows a remarkable sensitivity to frost and cold. In many semiarid areas of southern Italy, however, the occurrence of prolonged dry periods in summer and spring does not allow for the scheduling of summer crops without irrigation. However, the generally mild winter temperatures and the typical rainfall distribution, which is mostly concentrated over the winter months, could allow sowing time to be moved to the winter season to take advantage of the winter rainfalls. To evaluate the effect of moving the sowing time of coriander on seed yield and plant performance in semiarid Mediterranean environments, a field trial was performed in 1998-1999, 1999-2000, and 2000-2001 at Sparacia (Cammarata, AG, Sicily). Coriander seeds were sown in rows 50 cm apart every month for 5 mo from December to April. The fruits were harvested from mid-June to mid-July. The time from sowing to harvest was greatly dependent on the sowing date; the duration was 193 to 195 d for the December sowings, and 91 to 100 d for the April sowings. In all 3 yr, the most productive sowing time was December, and sowing after this date resulted in lower yields.