Response of Yield Parameters of Field Pea (Pisum sativum L.) to Different Shading Levels Under Rainfed Conditions

Reduced irradiance under shade nets may help cool-season legumes cope with the high radiation and heat load of late spring in semi-arid regions, but the response of field pea to graded shading under rainfed conditions is poorly documented. This study evaluated the yield and yield components of two field pea varieties (Araka and Yaprak) grown under full sunlight (control) and 40%, 75% and 90% shading in a two-year (2022 and 2023) rainfed field experiment in Diyarbakır, Türkiye, arranged as a split-plot randomized complete block design with three replications. Year, variety and shading level, and their interactions, significantly affected most traits, so responses were evaluated for each year and variety. Averaged over years and varieties, shading increased plant height by 24–27% relative to full sunlight, and 40% shading increased pod weight (+31%), number of seeds (+30%) and seed weight per plant (+25%). However, these per-plant gains did not translate into higher yield per unit area: biomass yield was highest under full sunlight (3.06 t ha−1) and decreased by 16–28% under shading, while seed yield under 40% shading (1.09 t ha−1) did not differ from that under full sunlight (1.10 t ha−1) and was reduced by 13% and 25% under 75% and 90% shading, respectively. Seed yield responses depended on variety and year: 90% shading reduced seed yield of both varieties in both years (by 9–35%), Araka yielded 19–24% more under 75% shading than under full sunlight in both years, and Yaprak gave its highest seed yield under 40% shading in 2022 (1.23 t ha−1) and under full sunlight in 2023 (1.96 t ha−1). After the year effect was removed, seed yield was closely correlated with biomass yield (r = 0.91) but not with the per-plant yield components. Heavy shading (90%) should therefore be avoided, whereas light shading (40%) can be applied without a yield penalty on average; the optimum level depends on variety and seasonal conditions.