基于全株生物量和全株氮浓度的马铃薯氮临界浓度稀释模型的构建及验证

  【目的】  临界氮浓度稀释曲线的构建是作物氮素营养诊断的基础，然而其曲线参数可能受品种等因素影响。本研究的主要目的是构建滴灌条件下常见马铃薯品种临界氮浓度稀释曲线模型，并利用相应的氮素营养指数进行马铃薯氮素营养诊断。  【方法】  于2014—2016年分别进行了滴灌条件下3个马铃薯品种、不同施氮量的田间试验。在马铃薯苗期、块茎形成期、块茎膨大期、淀粉积累期和收获期5个关键时期，进行地上部茎叶和地下部块茎取样，分别测定了生物量和氮浓度，根据公式计算出马铃薯全株生物量和全株氮浓度。根据全株生物量和全株氮浓度建立临界氮浓度稀释模型和相应的氮素营养指数。  【结果】  马铃薯地上部生物量和地上部氮浓度以及全株生物量和全株氮浓度都是随着生育时期的推进呈现出负幂函数关系，基于地上部生物量和地上部氮浓度建立的临界氮浓度稀释曲线决定系数平均为0.52，而以马铃薯全株生物量和全株氮浓度建立临界氮浓度稀释曲线决定系数平均为0.94，较前者提高了80%。以马铃薯全株生物量和全株氮浓度建立临界氮浓度稀释模型更为合理，且受品种影响较小，克新1号、夏坡地和荷兰14用同一个临界氮浓度稀释曲线的决定系数均达到0.95，表明构建的氮素营养模型可以进行不同品种的马铃薯氮素营养诊断。  【结论】  相对于传统籽粒型作物基于地上部生物量和地上部氮浓度建立临界氮浓度稀释模型，基于全株生物量和全株氮浓度建立的临界氮浓度稀释模型适用于不同品种马铃薯的营养诊断。在内蒙古滴灌生产条件下，马铃薯临界氮浓度稀释模型为Nc = 4.57W–0.41，基于该模型计算的马铃薯克新1号合理施氮量为N 170～180 kg/hm2、夏坡地合理施氮量为 190～200 kg/hm2、荷兰14合理施氮量为 215～225 kg/hm2。这些计算结果与试验结果的吻合度达到了0.95。

Establishment and validation of critical nitrogen dilution curve based on the total plant biomass and nitrogen concentration

  【Objectives】  The precision of critical nitrogen dilution curve for potato is not always satisfactory when used in the practical nitrogen nutrition diagnosis, due to the differences in nutrient characteristics of potato cultivars. We tried to construct and validate a critical nitrogen dilution curve that was available for most potato cultivars under drip irrigations in Inner Mongolia.  【Methods】  Three separate field experiments were conducted with different N rates and three potato cultivars under drip irrigation from 2014 to 2016. The above-ground shoots and under-ground tubers were sampled to determine the biomass and nitrogen concentration in five key periods of potato including seedling, tuber formation, tuber expansion, starch accumulation and harvest. The biomass and N concentration of whole potato plant were calculated according to a formula. The critical N dilution curve and the corresponding N nutrition index were established based on the biomass and N concentration of the whole plant.  【Results】  The biomass and N concentration of both the above-ground shoot and the whole plant showed a negative power function relationship with advance of growth stages. The average coefficient of determination (R2) of critical N dilution curve based on the biomass and N concentration of the above-ground shoot is 0.52, whereas the average R2 of the critical N concentration dilution curve based on the biomass and N concentration of the whole plant was 0.94, which was 80% higher than the former. Using the curve to predict the N requirement, the R2 of critical N dilution curve in Kexin 1, Shepody and Holland 14 all reached 0.95, indicating the availability of the models in the diagnose of potato N nutrition.  【Conclusions】  Compared with the critical N dilution curve established based on the biomass and N concentration of the above-ground part of a tuber crop like potato, the model based on the biomass and N concentration of the whole plant is more precise for the N nutrition diagnose. Under drip irrigation in Inner Mongolia, the N dilution model is Nc = 4.57W–0.41. According to this curve, the reasonable N application rate for Kexin1 is N 170–180 kg/hm2, for Shepody is 190–200 kg/hm2, and for Holland 14 is 215–225 kg/hm2, which are highly agreeable with the field experiment results.