油菜临界磷浓度稀释曲线模型的构建和验证

Construction and Validation of Critical Phosphorus Concentration Dilution Curve Model in Rape

构建基于地上部生物量的油菜临界磷浓度(Pc)稀释曲线模型,并利用此模型确定磷营养指数(PNI),为实现油菜磷肥精准管理提供科学参考。采用中双6号和华油杂9号2个油菜品种,在2020—2022年进行4个不同施磷量(0、35、70、105 kg/hm^(2),分别用P0、P35、P70、P105表示)的田间试验,在油菜关键生育时期测定地上部生物量(W)、植株磷浓度(PPC)及产量,通过统计分析和模型建立技术,构建和验证基于W的油菜Pc稀释曲线模型。结果表明,油菜W随生育时期的推进呈增加趋势,不同磷肥处理间表现为P0<P35<P70≈P105;而PPC则随W的增加呈下降趋势。增施磷肥可显著提高油菜产量,2个品种之间没有显著差异。油菜产量随磷肥用量的增加呈现先升高后降低的趋势,P70处理可达产量最高值,二次多项式方程拟合得到了油菜适宜的平均施磷量为81.8 kg/hm^(2),其理论平均产量可达到最高,为3595.83 kg/hm^(2)。建立了2个油菜品种统一的P_(c)稀释曲线模型(P_(c)=7.39W^(-0.16),R^(2)=0.80)。检验指标均方根误差(RMSE)为0.98 g/kg,标准化均方根误差(n-RMSE)为15.59%,模型稳定性较好。不同磷肥处理下PNI在0.56~1.11变化,在同一生育时期,PNI随施磷量的增加而上升。综合考虑油菜产量及PNI,推荐油菜适宜的施磷量为70.0~81.8 kg/hm^(2)。

The critical phosphorus concentration(Pc)dilution curve model of rape based on aboveground biomass was constructed,and the phosphorus nutrition index(PNI)was determined based on the model,which provided scientific reference for the precise management of phosphorus fertilizer in rape.Using two rapeseed varieties,Zhongshuang 6 and Huayouza 9,field experiments with four different phosphorus doses(0,35,70,105 kg/ha,represented by P0,P35,P70 and P105)were conducted in 2020 and 2021.The shoot biomass(W),plant phosphorus concentration(PPC)and yield were determined during the critical growth period of rapeseed,and the P_(c) dilution curve model based on W was constructed and validated through statistical analysis and model building techniques.The results showed that W of rapeseed increased with the advance of growth period,and showed the following characteristics among different phosphorus fertilizer treatments:P0<P35<P70≈P105.The PPC decreased with the increase of W.The yield of rapeseed was significantly increased by phosphorus fertilizer application,but there was no significant difference between the two cultivars.The yield of rapeseed increased first and then decreased with the increase of phosphorus fertilizer,and the highest yield was reached by P70 treatment.The optimal average phosphorus application rate of rapeseed was 81.8 kg/ha,and the theoretical average yield of rapeseed was 3595.83 kg/ha.A uniform Pc dilution curve model was established for the two rapeseed cultivars(P_(c)=7.39W^(-0.16),R^(2)=0.80).The root mean square error(RMSE)was 0.98 g/kg,the standardized root mean square error(n‑RMSE)was 15.59%,and the model had good stability.The PNI varied from 0.56 to 1.11 under different phosphorus fertilizer treatments.In the same growth stage,PNI increased with the increase of phosphorus fertilizer amount.By considering rapeseed yield and PNI,the recommended range of phosphorus application was 70.0—81.8 kg/ha.