Title: Effect of planting method and nitrogen rates on the yield and some agronomic traits of Rapeseed (Brassica napus L.) Delegan variety in different tillage systems as a second crop in paddy field
Author: Mohammad Rabiee
Abstract: In order to investigate the effects of tillage, planting method, and the levels of nitrogen fertilizer on the grain yield, energy use efficiency, and some agronomical traits of Rapeseed (Brassica napus L.) Delgan variety as the second crop after rice, a split factorial experiment in complete randomized block design was conducted with three replications at paddy fields of Rice Research Institute of Iran in Rasht during two cropping seasons of 2016-2018. In the experiment, three tillage methods including the conventional tillage, minimum tillage, and no-tillage were considered as the main plots and two planting methods of direct planting and transplanting as well as the four amounts of pure nitrogen fertilizer of 0, 100, 200 and 300 kg ha-1 from urea source as factorial in subplots. Results of the mean comparison showed that the second year with the average grain yield of 3348.6 kg/ha was significantly superior to the first year with an average of 3057.3 kg/ha. The interaction between tillage and planting method indicated that conventional and minimum tillage methods in the transplanting method with the averages of 3458.1 and 3360 .3 kg/ha had the maximum grain yield and were in the same group. The results of the interaction between the planting method and nitrogen amount demonstrated that the transplanting treatment at 300 kg/ha of nitrogen with the average grain yield of 4234.8 kg/ha had the highest grain yield. The no-tillage system had maximum soil bulk density (1.58 g cm-3), cone index (3.74 MPa), and soil moisture (72.13 percent). Among the experimental treatments, The treatments of conventional tillage with 300 kg ha-1 of nitrogen in both planting methods had the highest energy input due to more consumption of diesel fuel and nitrogen. The treatment of 100 kg ha-1 had the highest energy use efficiency and energy productivity. The results showed that the treatment combinations of conventional tillage and minimum tillage with 100 kg/ha of nitrogen, had the maximum value of agronomic efficiency, consumption efficiency, physiologic efficiency of nitrogen, and nitrogen apparent recovery. Based on the results, the treatment combination of minimum tillage at 200 kg ha-1 of nitrogen in both planting methods is recommendable for planting rapeseed in the Guilan region due to the high grain yield and reduction of fuel and energy consumption.
Keywords: Keywords: Tillage, Paddy field, Energy use efficiency, Canola, Transplanting, Nitrogen