Objectives Rapeseed and wheat are pivotal oilseed and cereal crops, respectively. However, frequent occurrences of low temperature and frost damage in central China have hindered the enhancement of their yields. We investigated the efficacy of various nutrient management measures in mitigating frost damage to rapeseed and wheat, aiming to provide technical references for nutrient management to support high-yield and high-quality production of rapeseed and wheat.
Methods A two-year field experiment was conducted at the Shayang Experimental Station of Huazhong Agricultural University from 2022−2023 and 2023−2024, employing two crop rotation systems: rapeseed-rice and wheat-rice. Each rotation system included six treatments: no fertilizer application (CK), 100% chemical fertilizer (NPK), 100% manures (M), 50% chemical fertilizer + 50% manures (1/2NPK+1/2M), 100% chemical fertilizer + rice straw returning (NPK+S), and 100% chemical fertilizer + rice straw returning + manures (NPK+S+M). The climatic conditions, rapeseed and wheat yields, yield components, and biomass over the two years were analyzed to assess the impact of freezing damage on rapeseed and wheat under different nutrient management practices.
Results The results of the two-year experiment revealed that, compared to the CK treatment, all the nutrient management practices significantly boosted the yields of rapeseed and wheat in both crop rotation systems. These practices primarily enhanced rapeseed and wheat yields by increasing the number of rapeseed siliques (by 293.7%) and wheat spikes per area (by 88.2%), improving rapeseed and wheat biomass (by 388.3% and 183.4%, respectively) and harvest index (by 2.1% and 7.3%, respectively). The NPK+S+M treatment exhibited the best yield-increasing effect, with increases in rapeseed and wheat yields of 479.7% and 290.9%, respectively. Freezing stress before the bolting stage of rapeseed and at the jointing stage of wheat in February 2024 led to an average yield reduction of 64.8% and 9.2% for all treatments of rapeseed and wheat, respectively. Rapeseed was significantly more affected by freezing damage than wheat in terms of yield reduction. Freezing stress significantly decreased the number of rapeseed siliques (by 25.7%) and biomass (by 67.5%), thereby limiting the final yield. Nutrient managements alleviated freezing damage on yield to different extents. Compared with normal year, freezing damage on yield and total biomass of rapeseed was the highest in CK treatment but the lowest in M treatment, even so, the highest yield and total biomass were still recorded in NPK+M+S treatment. Compared with CK, all five treatments promoted the relative accumulation of rapeseed dry matter and further increase in harvest index to reduce the reduction of rapeseed yield caused by freezing damage.
Conclusions Fertilization measures increase rapeseed and wheat yields by significantly increasing the number of rapeseed siliques and wheat spikes per area, enhancing biomass, and improving the harvest index. Among them, the combination of 100% chemical fertilizer + rice straw returning + manures yields the most favorable results in terms of production enhancement. Rapeseed is considerably more sensitive to frost damage than winter wheat. Freezing stress before the bolting stage of rapeseed can significantly reduce the number of siliques per plant and biomass of rapeseed. Although fertilization cannot fully recover the yield loss caused by frost damage, it can mitigate the impact of freezing stress on rapeseed by promoting the accumulation of dry matter in the aboveground parts of rapeseed and increasing the harvest index, and the yield reduction in rapeseed when using 100% organic fertilizer (M) can be minimized. However, the specific roles of manures in combating frost warrant need further research.
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