Adjusting Sowing Date and Seeding Rate for Cultivated Lentil to Contrasting Rainfall Conditions in a Semi-arid Region

Adjusting the sowing date and seeding rate of lentils are important practices, which largely affect plant performance and need greater focus under semi-arid conditions. Our study aimed to optimize the sowing window and plant density specific to dry and wet conditions. A two-year field experiment was carried out under dry and wet cropping seasons (2016/2017 and 2017/2018). Two commercial lentil varieties (Syrie229 and Idleb2) were sown at early (late October/early November), normal (December), and late (January) sowing dates and with low (90 seeds/m2), medium (120 seeds/m2) and high (150 seeds/m2) seeding rate. Several traits were recorded namely plant height at first filled pod (HFFP), plant height (PH), days to flowering (DTF), days to maturity (DTM), stem diameter (SD), weight of 100 seeds (100-SW) and seed yield (SY). Our results revealed that the dry year considerably reduced all trait values except the weight of 100 seeds compared to the wet year. Sowing date had a significant effect on most traits, with the highest values being found for early sowing date compared to normal and late dates, including seed yield (1.83 vs. 1.36 and 0.94 ton/ha, respectively). It is worth noting that the difference among sowing dates was detected only under wet years for most traits. The seeding rate affected only HFFP and stem diameter under a wet year, where a high seeding rate increased HFFP while a low seeding rate increased stem diameter. To conclude, cropping season was the main driver of growth and yield, and then the effect of sowing date was dependent on climatic conditions. Our results highlight the importance of adjusting the sowing window and seeding rate to cope with the future climatic change effects.