施氮量对菊芋块茎产量、品质与植株生理特性的影响

李岚涛; 张铎; 盛开; 耿赛男; 石纹碹; 苗玉红; 王宜伦

doi:10.11674/zwyf.2021395

摘要:

目的氮肥不合理施用在导致资源浪费和环境问题的同时，还会影响菊芋正常生长发育和产量形成。研究施氮量对成熟期菊芋块茎产量、品质和生育期生理特性影响，确定关键营养指标，为菊芋高产高效施用氮肥提供理论支撑。

方法菊芋氮肥梯度田间试验于2019年在河南省新乡市原阳县、2020年在南阳市方城县开展，2019年设N 0、60、120、180、240和300 kg/hm² 6个氮处理，2020年则分别设N 0、90、180、270和360 kg/hm² 5个氮处理。于菊芋营养生长前期、营养生长中期、营养生长末期和开花期采集植株样品，测定地上部植株氮含量、叶片绿原酸含量、SPAD值和可溶性糖、可溶性蛋白、木质素和纤维素含量等理化指标，并于成熟期测定菊芋块茎产量和菊糖、还原糖含量等品质指标。利用偏最小二乘(partial least square, PLS)回归模型定量分析各理化指标与产量、品质间关系，确定关键营养指标。

结果 1)随着氮肥施用量的增加，2019和2020年度菊芋块茎产量均呈“线性+平台”趋势变化，2019和2020年适宜施氮量分别为232和270 kg/hm²。2)成熟期菊芋块茎菊糖和还原糖含量均随施氮量增加呈“先升高后趋于稳定”的趋势。与不施氮对照相比，施氮处理菊芋块茎菊糖和还原糖含量两年度增幅分别平均为19.4%和47.3%，效果显著。3)各生育期菊芋地上部植株氮素积累量、叶片绿原酸含量、SPAD值、可溶性糖含量、可溶性蛋白含量和纤维素含量等指标均随施氮量增加而明显提高，木质素含量则逐步降低。4) PLS模型结果显示，菊芋地上部植株氮素积累量、叶片绿原酸含量、SPAD值、可溶性糖含量、可溶性蛋白含量、木质素和纤维素含量等理化指标与块茎产量、菊糖和还原糖含量间表现出较好的回归关系，决定系数(coefficient of determination，R²)分别为0.648、0.618和0.629，相对分析误差(relative percent deviation，RPD)分别为1.676、1.638和1.659，模型精度较为理想。此后，基于PLS模型中各指标无量纲评价指标变量重要性投影值(variable importance for projection，VIP)，确定叶片SPAD值为影响菊芋块茎产量和还原糖含量的关键指标，影响块茎菊糖含量的关键指标则为叶片绿原酸含量，VIP值均高于临界值1.0。

结论合理施氮可显著提高菊芋成熟期块茎产量，改善品质，增强各生育期生理活性，本试验条件下菊芋适宜施氮量为230～270 kg/hm²。

Abstract:

Objectives The study was designed to investigate the effects of nitrogen (N) application rates on tuber yield, quality and plant physiological activities of Helianthus tuberosus L. and identify the key indicators based on the partial least square model (PLS).

Methods Field experiments were conducted separately in Yuanyang County in 2019 and Fangcheng County in 2020, Henan Province, China. The tested N application rates were 0, 60, 120, 180, 240, and 300 kg/hm² in 2019, and 0, 90, 180, 270, and 360 kg/hm² in 2020. At the early, middle, and late vegetative and flowering periods, plant samples were collected for the chemical analysis of plant N content, leaf chlorogenic acid content, leaf SPAD value, soluble sugar, soluble protein, lignin and cellulose content. Meanwhile, the tuber yield, inulin and reducing sugar content were analyzed at maturing stage. The PLS model was employed to quantitatively describe the relationship among the above-mentioned indices and identify the main controlling factors of Helianthus tuberosus L. tuber yield inulin, and reducing sugar.

Results 1) The tuber yield of Helianthus tuberosus L. increased with increasing N application rates in “linear + platforms trends”. The optimal N application rate was 232 and 270 kg/hm² in 2019 and 2020. 2) The inulin and reducing sugar content in Helianthus tuberosus L. tubers stopped increasing when the N application rate reached 300 and 270 kg/hm². Compared with the N0 treatment, N application increased inulin and reducing sugar content by 19.4% and 47.3% on average in 2 years, respectively. 3) The plant N accumulation, leaf chlorogenic acid content, leaf SPAD value, soluble sugar, soluble protein and cellulose content increased with increasing N application rates except for the leaf lignin content. 4) The PLS models between the indicators and the tuber yield, inulin and reducing sugar content showed a good correlation, with R² values of 0.648, 0.618, and 0.629, and the relative percentage deviation (RPD) values of 1.676, 1.638, and 1.659, respectively. Moreover, the variable importance for projection (VIP) values calculated with the PLS models developed showed that the main controlling factors of tuber yield, reducing sugar and inulin content of Helianthus tuberosus L. were the leaf SPAD value and the leaf chlorogenic acid content, respectively.

Conclusions N fertilizer application could improve tuber yield and quality and enhance the physiological and biochemical indicators of Helianthus tuberosus L. The appropriate N application rate for Helianthus tuberosus L. for improved growth, tuber yield, and quality in the experimental area was N 230–270 kg/hm².

施氮量对菊芋块茎产量、品质与植株生理特性的影响

Effects of nitrogen application rates on tuber yield, quality and plant physiological activities of Helianthus tuberosus L.