Assessing chickpea attainable yield and closing the yield gaps caused by agronomic and genetic factors

Context or problem: Agricultural production in the world has drastically increased to meet future food demand. Yield gap assessment provides important information on how production can be increased on existing cropland. Also, boosting food production by reducing the yield gap has fewer environmental consequences than increasing the food production area.Methods: For this purpose, the SSM-Legume model was evaluated and used to simulate chickpea rainfed potential production, rainfed potential production of chickpea with actual sowing date (YRS), plant density (YRD) and nitrogen fertilizer (YRN), practiced by farmers as well as yield gaps due to improper sowing date (YGS), plant density (YGD), nitrogen limitation (YGN), and yield gap due to other limiting and reducing factors (YGO) at 12 chickpea producing locations of Iran.Results: Our results showed that at national scale, the mean total yield gap (YG) was 67%, indicating chickpea grain yield achieved by farmers was only 33% of attainable yields (YA) during the past 3 decades. Furthermore, the YG was 28% higher for the new early-maturity cultivar (Adel) than for the old early-maturity cultivar. Nationally, across two cultivars, the most significant share of YG belonged to YGO (45%), followed by YGS (40%), YGD (8%), and YGN (6%). However, the share of each YGO, YGS, YGD, and YGN in YG varied based on region. The highest YG was related to YGO (67%) in all studied regions (except west). Furthermore, the greatest share of YG belonged to YGS (79%) in western regions. The mean YGD was lower than 10% in all regions (except in the south and the west). There was a small yield gap due to farmers' lack of starter nitrogen fertilizer, which varied from 2% in the south to 10% in the west.Conclusions: Overall, our results approved that there was the low agronomic efficiency of chickpea cultivation despite resource accessibility in these regions. In other words, the replacement of the old-early maturity cultivar (Beavanij as check cultivar) with the new early-maturity cultivar (Adel) would increase attainable yield by 28% that shows the genetic effect. However, we can argue that chickpea yield in studied locations is limited mainly by other limiting and reducing factors (YGO) and not the genetics of the current cultivars or sowing date, plant density, and nitrogen.Implications or significance: The current research focused on both genetic and management effects influencing on closing the yield gaps and introduced new cultivars and optimal management practices to reduce chickpea grain yield based on various environment conditions.

Automated summary

Agricultural production has increased to meet future food demand, and assessing the yield gap provides important information on increasing production on existing cropland. This study evaluated the SSM-Legume model and simulated the potential production and yield gaps of chickpea in Iran. The results showed that the average yield gap was 67% at the national scale.