Effects of potassium fertilizer rates on tuber yield，plant physiological characteristics and potassium absorption and utilization of Helianthus tuberosus L.

Abstract

为了探究钾肥用量对菊芋块茎产量、植株生理特性及钾素吸收利用影响效应，为菊芋科学施钾及优质高产栽培提供参考依据，2022 年于河南省原阳县河南农业大学科教园区布置钾肥用量田间试验，设置 0（K0）、45（K45）、90（K90）、135（K135）、180kg·hm^-2 （K180）和 225 kg·hm^-2（ K225）K₂O六个处理，系统研究钾肥用量对成熟期菊芋块茎产量（播种后 206 d）及生育期间（播种后60、94、122 d和162 d）植株钾素积累量、冠层光合有效辐射[有效辐射量（APAR）和吸收系数（FPAR）]、冠层温度、叶片SPAD值、叶片解剖结构和抗氧化酶活性等理化特性，分析计算钾素收获指数、钾肥表观利用率和农学效率相关指标。结果表明：施钾可显著提高菊芋块茎产量，钾肥用量与块茎产量间变化趋势符合一元二次方程效应函数，适宜施钾量为204 kg·hm^-2。生育期间，随钾肥用量增加，菊芋相关生理指标（植株钾素积累量、APAR、FPAR、叶片SPAD值、上下表皮厚度、叶片厚度、栅栏组织厚度、海绵体厚度、抗氧化酶活性）均呈先上升后下降的变化趋势；冠层温度变化趋势则与之相反，且各指标均在施钾量为180 kg·hm^-2时达至最优。菊芋钾肥表观利用率和农学效率随钾肥用量增加呈先升高后降低趋势，钾素收获指数总体则呈逐渐降低趋势。研究表明，合理施肥可显著增加菊芋块茎产量，改善菊芋生育期内生理活性，提高菊芋的抗逆性和钾肥利用效率。在豫北平原砂质潮土条件下，菊芋适宜施钾量为180~204 kg·hm^-2。

This study aimed to explore the effects of potassium application rates on tuber yield, plant physiological characteristics, potassium absorption and utilization of Helianthus tuberosus L., and thus to provide a reference for scientific application of potassium and high-quality and high-yield cultivation of H. tuberosus. A field experiment was conducted in the Science and Education Park of Henan Agricultural University in Yuanyang County, Henan Province, in 2022. Six treatments of 0（K0）, 45（K45）, 90（K90）, 135（K135）, 180 kg·hm^-2（K180）, and 225 kg·hm^-2（K225）K₂O were used. Tuber yield was measured at the maturity stage（206 d after sowing）, potassium accumulation, canopy photosynthetic effective radiation（APAR and FPAR）, canopy temperature, leaf SPAD value, leaf anatomical structure, and antioxidant enzyme activity were measured during the growth period（60, 94, 122 d, and 162 d after sowing）. In addition, potassium harvest index（PHI）, apparent use efficiency of potassium（AUP, %）and agronomic efficiency of potassium（AEP, kg·kg^-1）for H. tuberosus were analyzed. The results showed that potassium application could significantly increase the fresh yield of H. tuberosus. The optimal potassium fertilization rate for the growing season was 204 kg ·hm^-2. With the increase of potassium fertilizer rate, the relevant physiological indicators of H. tuberosus（plant potassium accumulation, APAR, FPAR, leaf SPAD value, upper and lower epidermis thickness, leaf thickness, palisade tissue thickness, cavernous tissue thickness, and antioxidant enzyme activity）showed a trend of first rising and then declining

canopy temperature change showed the opposite trend. All indicators reached their optimal values at a potassium fertilizer rate of 180 kg·hm^-2. AUP and AEP showed a trend of first increasing and then decreasing with the increase of potassium fertilizer dosage, whereas PHI showed a gradually decreasing trend. In summary, the yield of H. tuberosus tubers was significantly improved by increasing rates of potassium, and the physiological activity, stress resistance, and potassium fertilizer utilization were also improved. With the conditions of sandy tital soil in northen Henan, the recommended potassium fertilizer rate for H. tuberosus is 180-204 kg·hm^-2.