Yield gap analysis simulated for sugar beet-growing areas in water-limited environments

Abstract Sugar beet is one of the main two field crops cultivated to extract sugar. In order to increase the production of sugar beet, it is necessary to identify limiting and reducing factors by quantifying and analyzing yield gap. For this purpose, a crop simulation model was evaluated and used to simulate the storage organ of the sugar beet as well as yield gaps due to water shortage, inappropriate sowing date, and other biotic and abiotic factors at 10 locations of Khorasan Razavi province in northeastern Iran. Results of long-term simulations indicated that the province has a good potential for sugar beet yield with the highest yield of 103.6 t ha−1. However, there is a huge difference between actual production level and simulated attainable one (65.4 t ha−1); the average actual yield was only 32.7 % of the simulated attainable yield. In spite of the large amount of water applied as irrigation by most farmers, there are still water limitations because of water mismanagement, high vapor pressure deficit, and the temperatures occurring during most sensitive the major sugar beet growth stages at most locations. On average, water limitation had a major influence on yield gap (47.5 % of total yield gap) compared with sowing date (15 %) and other limiting and reducing factors (37.5 %). Under these circumstances, farmers must focus on increasing the water productivity of the sugar beet agroecosystem by replacing the current furrow irrigation systems, sowing earlier crops, and substituting sugar beet with crops that have a shorter growing season and are better adapted to the hot and arid climate during summer.