马铃薯钾素营养状况的实时评价及钾肥推荐

In the classical crop potassium fertilizer recommendation method basing on soil test, Potassium Requirement of Crop for producing unit grain yield and Soil Available Potassium Content are two key parameters to determine the K fertilizer application rate for cereal crops. However, the K requirements to produce unit potato tuber yield vary greatly, and poor relationship between soil exchangeable K content and potato yield has been observed, which results in poor indication of soil exchangeable K content to potato K fertilization. Thus, potato potassium recommendation basing on Plant K Requirement and Soil Available K Content becomes uncertain. Therefore, the real-time monitoring of the potato plant K nutritional status is necessary for potato precise K fertilizer management. This project aims to investigate how potato petioles K contents vary along with plant growth and soil K contents, then determine the threshold value for diagnosing potato K nutritional status by using portable K electrode, and finally establish potato potassium recommendation model basing on the real-time diagnosis. Due to the reason that sandy soil has poor water and fertilizer retention capacity, which is main soil texture in the potato growing area of Inner Mongolia, split application of K fertilizer can significantly improve potato yield and the fertilizer use efficiency there. In addition, drip irrigation technology is being rapidly extended in the potato production area, which facilitates K fertilizer split application greatly. Therefore the implementation of the project will not only further reveal potato potassium nutrition characteristics but also provide guidance for the potato K fertilization practice.

马铃薯是需钾较多的作物。然而，与谷类作物不同，单位块茎产量的马铃薯钾素需求量存在巨大变异，而且由于马铃薯是典型的浅根系作物，养分吸收能力差，导致土壤速效钾含量对马铃薯钾肥推荐的指示性差，所以依据单位经济产量作物需钾量和土壤速效钾含量两个关键参数进行的测土施肥经典方法在马铃薯上出现较大的偏差。基于此，马铃薯植株钾素营养状况的实时诊断对钾肥管理显得十分必要。本项目拟在阐明马铃薯叶柄K含量变化规律的基础上，建立使用便携式K电极进行马铃薯实时钾素营养诊断的方法，确立内蒙古产区马铃薯不同生育阶段叶柄K的临界指标，提出基于植株实时诊断的钾肥分期调控指标体系。该项目的实施完成将克服测土施钾存在的不确定性，丰富马铃薯的钾素营养与施肥理论，而且由于内蒙古马铃薯产区土壤多为沙性质地，钾肥分期施用被大力提倡,因此该项目的完成将为当地马铃薯钾肥分期管理实践提供指导。

由于单位经济产量（块茎产量）的马铃薯钾素需求量存在巨大变异，而且土壤速效钾含量对马铃薯钾肥推荐的指示性差，所以依据单位经济产量作物需钾量和土壤速效钾含量两个关键参数进行的测土施肥经典方法在马铃薯上常出现较大的偏差。基于上述问题，探索分析开展马铃薯植株钾素营养状况实时诊断的可行性和实现途径具有重要科学意义，其为马铃薯钾肥管理精准化的基础和前提。本项目从2018到2021年，通过进行多点田间试验，观察了马铃薯钾素吸收及积累、块茎产量随土壤供钾水平的变化特点，证实了马铃薯的奢侈吸钾现象，研究发现了马铃薯叶柄含钾量随生育进程逐渐降低的变化规律以及对土壤供钾水平反应敏感的特点；探索建立了使用便携式K离子电极进行马铃薯实时钾素营养诊断的方法（包括测定叶位、样本数量、叶柄汁液取样方法、测试等关键环节），通过大量检验，证实了该法获得的叶柄K速测值与经典实验室测定值具有良好的正相关关系（r=0.92）；进一步研究确立了内蒙古产区马铃薯主栽品种“克新一号”不同生育阶段叶柄速测K的临界指标，在苗期（~30DAE）、块茎形成期（~45DAE）、块茎膨大期（~60DAE）和淀粉积累期（~75DAE），马铃薯倒4叶柄柄速测K临界值分别为5833、4953、4248和3205ppm，为判断马铃薯不同生育阶段钾营养状况确立了标准；在此基础上，研究提出了基于植株实时诊断的钾肥分期管理的模型。上述研究结果不仅进一步阐明了马铃薯钾素营养规律，而且建立的诊断方法和推荐施肥模型克服了测土施钾存在的不确定性，丰富了马铃薯的钾素营养与施肥理论。另外，由于内蒙古马铃薯产区土壤多为沙质，钾肥分期施用被大力提倡,而且滴灌技术的引进为分期施肥提供了便利，因此上述成果将为当地马铃薯钾肥分期管理实践提供具体指导。