Effect of different boron fertilizers on seed yield and seed quality of oilseed rape (Brassica napus) and their residual effectiveness for rotated rice

The effects of two kinds of boron (B) slow-release fertilizers, Etibor-48 (EB; Na2B4O7?5H2O) and Colemanite (CB; Ca2B6O11?5H2O), on seed yield and seed quality of oilseed rape (Brassica napus) and their residual effectiveness for rotated rice were investigated in pot culture experiments and field trials, respectively. Seed yield of oilseed rape in the EB and CB treatments was significantly higher than that in the absence of boron (B), and higher than that of borax treatment (B) for the first crop. Field trial results of the first crop (oilseed rape) in Anhui province, China, were consistent with those of the pot culture experiments. Grain yield of the second crop (rice) in all B fertilizer treatments was slightly higher than that of the B treatment in the pot culture experiment; however, there was no significant difference in seed yield between the B application treatments (EB and CB) and B treatment in field trials in both Anhui and Hubei provinces. Pot culture experiments indicated that seed yield of the third crop (oilseed rape) was significantly lower than that of the first crop. In addition, there was no significant difference in seed yield of oilseed rape among the B fertilizer treatments, but seed yield in these treatments was significantly higher than that of the B treatment. Seed yield of the third crop of oilseed rape in both B application treatments was also higher than that of the B treatment and CB achieved the highest seed yield in field trials in Anhui province. Split plot experiments indicated that seed yield of oilseed rape in all B application treatments was slightly higher than that of each corresponding ?B treatment for the third crop, and there was no significant difference in seed yield among the B application treatments. Residual effectiveness in the field trials conducted in Anhui and Hubei were not consistent, which could be attributed to a higher soil-available B content in the Hubei experimental plot than that in Anhui. For B-deficient soils, B application can not only increase seed yield, but also improve seed quality of oilseed rape, whereas B application had little effect on grain quality of rice. These results will be helpful to optimize management of B in oilseed raperice crop rotation systems in the middle and lower reaches of the Yangtze River.