Yield Gap Estimation of Rapeseed (Brassica Napus L.) in Northern Iran

Abstract

Understanding yield-limiting traits can help researchers reduce yield gap, a key step in increasing yield and sustainability. This aim of research was monitoring 100 fields of farmers to identify the most important variables to enter into a CPA model (comparative performance analysis) for the yield gap in northern Iran in 2016 to 2017. Of the 150 variables studied in the first experiment, eight independent variables were chosen for the final model. In the yield model, the average and maximum yields were 2536 and 4265 kg ha-1 , respectively, with an estimated yield gap of 1729 kg ha-1 . This yield gap was related to seed usage, planting date, fallow and rice cover-crop equal’s 124, 101, 242 and 245 kg ha-1 includes 7.17, 5.84, 14 and 14.17% of total yield increase. The yield increasing related to the effect of crop rotation, potassium usage, nitrogen after flowering and top-dressing frequency was 212, 295, 314 and 196 kg ha-1 equals 12.26, 17.06, 18.16 and 11.34%. Accordingly, the model’s precision is good and can be applied both to estimate the quantity of yield gap and to determine the portion of each constraint in the yield variables. Importantly, as the calculated yield potential is reached based on actual data in each paddy field, the yield potential is attainable.