Effects of a controlled-release fertilizer on yield, nutrient uptake, and fertilizer usage efficiency in early ripening rapeseed(Brassica napus L.)

Background： Nitrogen（N）, phosphorous（P）, and potassium（K） are critical nutrient elements necessary for crop plant growth and development. However, excessive inputs will lead to inefficient usage and cause excessive nutrient losses in the field environment, and also adversely affect the soil, water and air quality, human health, and biodiversity. Methods： Field experiments were conducted to study the effects of controlled-release fertilizer（CRF） on seed yield, plant growth, nutrient uptake, and fertilizer usage efficiency for early ripening rapeseed（Xiangzayou 1613） in the red-yellow soil of southern China during 2011–2013. It was grown using a soluble fertilizer（SF） and the same amounts of CRF, such as SF1/CRF1（3750 kg/hm^2）, SF2/CRF2（3000 kg/hm^2）, SF3/CRF3（2250 kg/hm^2）, SF4/CRF4（1500 kg/hm^2）, SF5/CRF5（750 kg/hm^2）, and also using no fertilizer（CK）. Results： CRF gave higher seed yields than SF in both seasons by 14.51%. CRF4 and SF3 in each group achieved maximum seed yield（2066.97 and 1844.50 kg/hm^2, respectively）, followed by CRF3（1929.97 kg/hm^2） and SF4（1839.40 kg/hm^2）. There were no significant differences in seed yield among CK, SF1, and CRF1（P0.05）. CRF4 had the highest profit（7126.4 CNY/hm2） and showed an increase of 12.37% in seed yield, and it decreased by 11.01% in unit fertilizer rate compared with SF4. The branch number, pod number, and dry matter weight compared with SF increased significantly under the fertilization of CRF（P0.05）. The pod number per plant was the major contributor to seed yield. On the other hand, the N, P, and K uptakes increased at first and then decreased with increasing the fertilizer rate at maturity, and the N, P, and K usage efficiency decreased with increasing the fertilizer rate. The N, P, and K uptakes and usage efficiencies of the CRF were significantly higher than those of SF（P0.05）. The N accumulation and N usage efficiency of CRF increased by an average of 13.66% and 9.74 percentage points, respectively, compared to SF. In conclusion, CRF significantly promoted the growth of rapeseed with using total N as the base fertilizer, by providing sufficient N in the later growth stages, and last by reducing the residual N in the soil and increasing the N accumulation and N usage efficiency.

Proteomic analysis of differentially expressed proteins between Xiangyou 15 variety and the mutant M15

A high oleic acid rapeseed material MI5 （derived from Xiangyou 15 variety） has been received more attention for its significant effect for human health. And it has almost the same physiological characteristic with Xiangyou 15 variety. To find out the difference between high oleic acid rapeseed material and Xiangyou 15 seedling, a comparative proteomic approach based on 2-DE and mass spectrometry was adopted. A total of 277 protein spots showed a significant change in intensity by more than 2.0-fold from M15 compared with Xiangyou 15 variety. Among them, 48 spots that changed at least 3.0-fold were excised from gels and successfully identified by MALDI-TOF/TOF MS. The identified proteins involved in metabolism of carbohydrate and energy （75%）, stress and defense （8.3%）, photosynthesis （6.3%）, protein metabolism （2.1%） and other functions （8.3%）. Then real-time quantitative PCR （qPCR） analysis was used to verify the expression levels of differentially expressed proteins, but the results did well agree with the proteomic results. In this work, most of the proteins involved in metabolism of carbohydrate and energy have higher expression in M15, which may reveal M15 has higher metabolism ability. These results provided much information to understand the differences between high oleic acid rapeseed material and Xiangyou 15 variety, which will be useful to screen high oleic rapeseed materials in seedling period.