关中平原冬小麦临界磷浓度稀释曲线的构建与磷营养诊断

Construction of critical phosphorus concentration dilution curve and phosphorus nutrition diagnosis of winter wheat in Guanzhong plain

【目的】基于关中平原冬小麦施磷量与小麦磷营养的关系,建立临界磷浓度稀释曲线,为当地冬小麦科学施磷提供理论依据。【方法】长期定位施磷田间试验始于2009年,供试小麦品种为‘西农979’。设置4个施磷水平(PO)0、60、120、180 kg/hm^(2),分别记为P0、P60、P120和P180处理。于2018—2021年冬小麦拔节期、孕穗期、开花期、灌浆期和成熟期取样,分析冬小麦地上部生物量、植株磷浓度,记录小麦产量。利用2018—2020年冬小麦地上部生物量和植株磷含量建立临界磷浓度稀释模型,计算磷营养指数(PNI)。依据2020—2021年冬小麦数据验证磷营养指数诊断的可靠性。【结果】1)施用磷肥可显著增加冬小麦穗数和穗粒数,显著降低千粒重,2018—2021年3季冬小麦依次提高穗数50.7%~53.0%、23.1%~29.7%和17.5%~19.0%,穗粒数依次提高28.6%~34.2%、22.7%~24.1%和18.7%~19.6%,千粒重依次降低1.1%~2.9%、3.5%~7.0%和1.3%~4.9%,P60、P120和P180处理间穗数、穗粒数(2018—2019年除外)差异不显著。随着施磷量增加,冬小麦籽粒产量先持续增高而后降低,施磷处理下2018—2021年3季冬小麦依次增产104.3%~108.2%、39.8%~47.4%和27.6%~32.5%,在P120处理下产量达到最大值,2018—2021年3季依次为7100、6369和6714 kg/hm^(2)。2)冬小麦地上部生物量随生育进程的推进逐渐增加,地上部磷浓度随生育进程推进逐渐降低。同一取样时期,施磷量增加,地上部生物量和磷浓度也随之增加。据此,本研究2019—2020年建立的临界磷浓度稀释曲线模型为Pc=6.00DM–0.43,模型RMSE值为0.09,n-RMSE值为3.45%,表明模型模拟值的可靠性和稳定性达到要求。3)随着施磷量增加,磷营养指数(PNI)增大,磷营养指数(PNI)在P120处理下最接近1。各施磷量处理下,冬小麦磷营养指数(PNI)随生育期的变化较小。【结论】依据不同施磷量下冬小麦地上部生物量和磷浓度,建立的临界磷浓度稀释曲线模型与磷营养指数(PNI)模型能够准确诊断关中平原冬小麦不同生育阶段的磷素盈亏状况,可用来指导关中平原冬小麦植株各生育期磷素含量评估和磷肥施用。

【Objectives】Based on the relationship between winter wheat phosphorus application rate and wheat phosphorus nutrition in Guanzhong Plain,we established a critical phosphorus concentration dilution curve to provide a theoretical basis for meeting the P needs of local winter wheat.【Methods】The long-term localization phosphorus field experiment was established in 2009,and the wheat variety was Xinong 979.The four phosphorus application treatments(PO)tested were 0,60,120,180 kg/hm^(2),noted as P0,P60,P120 and P180,respectively.The above-ground plant samples were determined at the jointing,booting,flowering,filling,and maturity periods of the winter wheat from 2018 to 2021,and the above-ground biomass and plant phosphorus concentration were analyzed,the wheat yield was also evaluated.A critical phosphorus concentration dilution model was used to calculate the P nutrient index(PNI).The reliability of phospho-nutrition index was verified based on winter wheat data from 2020 to 2021.【Results】1)P fertilization significantly increased the panicle number in three seasons by 50.7%–53.0%,23.1%–29.7%,and 17.5%–19.0%,increased the grain number per panicle by 28.6%–34.2%,22.7%–24.1%and 18.7%–19.6%,but reduced 1000-grain weight by 1.1%–2.9%,3.5%–7.0%and 1.3%–4.9%,respectively.The panicle number elicited by P120 and P180 treatments were similar.With the increase in P application rate,the grain yield increased first and then decreased,and the yield in the three seasons was increased by 104.3%–108.2%,39.8%–47.4%,and 27.6%–32.5%on average,with the maximum yield of 7100kg/hm^(2),6369 kg/hm^(2),and 6714 kg/hm^(2)under the P120 treatment.2)The aboveground biomass of winter wheat gradually increased with the progress in the growth process,and the P concentration in the upper aboveground part gradually decreased.Based on the aboveground biomass and P concentration of winter wheat in 2019—2020,a critical P concentration dilution curve model was established:Pc=6.00DM–0.43,with the RMSE of 0.09,and nRMSE of 3.45%,indicating that the reliability and stability of the model simulation values meet the requirements.3)The PNI of wheat was mainly affected by P application rate,not by growing stage.P120 treatment had the PNI closest to 1.【Conclusions】Based on above-ground biomass and P concentration of winter wheat under different P application rates,the critical phosphorus concentration dilution curve model and P nutrition index(PNI)model can ideally diagnose the status of phosphorus,balance in winter wheat in Guanzhong plain,and can be used as a tool for phosphorus content assessment and guidance of phosphorus fertilizer application.