种植密度对菊芋块茎产量、植株光能截获及养分转运特性的影响

Effects of planting density on tuber yield,plant light energy utilization and nutrient transport characteristics of Helianthus tuberosus

【目的】探究种植密度对菊芋块茎产量、植株光能截获及养分吸收转运特性的影响,确定适宜种植密度,为菊芋优化栽培种植及高产稳产提供理论依据。【方法】2019—2020年分别于河南省新乡市和南阳市布置菊芋密度效应田间试验。以“南芋1号”为供试材料,设置5个种植密度,分别为:D1(1.80×10^(4)株·hm^(-2))、D2(2.25×10^(4)株·hm^(-2))、D3(2.70×10^(4)株·hm^(-2))、D4(3.15×10^(4)株·hm^(-2))和D5(3.60×10^(4)株·hm^(-2))。于菊芋成熟期(mature period,MP)测试块茎产量,并分别于营养生长中期(medium the vegetative period,MVP)、营养生长末期(late the vegetative period,LVP)和开花期(flowering period,FP)测试地上部植株生物量和氮磷钾养分含量,分析计算菊芋植株养分积累与开花期、花后养分转运特性。同时于上述生育期测定菊芋不同叶层叶片SPAD值和冠层光分布。【结果】种植密度可显著影响菊芋块茎产量,2019和2020年两者间关系可分别用“线性+平台”和“一元二次方程”拟合,2 a适宜种植密度分别为3.15×10^(4)和3.24×10^(4)株·hm^(-2)。随种植密度增加,菊芋上层叶片SPAD值无明显差异,但随叶层下移,密度间叶片SPAD值差异性则显著增加,即密度越小,中、下层叶片SPAD值越高。菊芋冠层吸收性光合有效辐射量(APAR)和吸收系数(FPAR)则随密度增加而显著提高。试验点和密度处理双因素交互效应分析表明,试验点对菊芋块茎产量、叶片SPAD值、FPAR和APAR均有显著影响,试验处理对以上指标影响均达到显著效应;两因素交互作用仅对FPAR影响显著,对其他指标均无明显影响。此外,随种植密度增加,菊芋各生育期氮磷钾养分积累量则显著升高;开花期养分转运量逐步增加,转运率则逐步下降;花后养分转运量和养分转运率总体均呈升高趋势。【结论】适度种植可显著提高菊芋块茎产量,增强植株冠层光能截获与利用性能,提高氮磷钾养分吸收、储存与转运能力。本试验条件下,菊芋适宜种植密度为3.15×10^(4)~3.30×10^(4)株·hm^(-2)。

【Objective】To explore the effects of planting density on tuber yield,plant light energy interception and nutrient absorption and transport characteristics,identify the optimal planting density,and provide theoretical basis for optimal cultivation and high and stable yield of Helianthus tuberosus.【Method】Field experiments about density effects of Helianthus tuberosus were conducted in Xinxiang city and Nanyang city of Henan Province during 2019—2020.The“Nanyu No.1”was adopted as the test material,and five density treatments were set up,i.e.,D1(1.80×10^(4) plants·hm^(-2)),D2(2.25×10^(4) plants·hm^(-2)),D3(2.70×10^(4) plants·hm^(-2)),D4(3.15×10^(4) plants·hm^(-2))and D5(3.60×10^(4) plants·hm^(-2)),respectively.Tuber yield was measured at maturity period(MP),and aboveground biomass,nitrogen,phosphorus and potassium content were measured at medium vegetative growth(MVP),late vegetative growth(LVP)and flowering(FP)stage,respectively.The nutrient accumulation and nutrient transport characteristics of Helianthus tuberosus plants at flowering period and after anthesis were analyzed and calculated.In addition,the SPAD value and canopy light distribution at different leaf layers of Helianthus tuberosus were also measured at the above growth stages.【Result】Planting density can significantly affect the tuber yield.In 2019 and 2020,the relationship between planting density and tuber yield can be fitted with linear+platform and univariate quadratic equation.The suitable planting density for two years were 3.15×10^(4) and 3.24×10^(4) plants·hm^(-2),respectively.With the increase of planting density,there was no significant difference in SPAD value of upper leaves,but with the downward movement of leaf layer,the difference in SPAD value of leaves among different densities increased significantly,that is,the smaller the density,the higher the SPAD value of leaves in the middle and lower layers.The absorptive photosynthetic effective radiation(APAR)and absorption coefficient(FPAR)of Helianthus tuberosus canopy increased significantly with the increase of density.The analysis of two-factor interaction effect between test site and density treatment showed that the test site had significant effects on tuber yield,leaf SPAD value,FPAR and APAR.The experimental treatments had a significant effect on the above indexes.The interaction of two factors only had a significant impact on FPAR,but had no significant impact on other indicators.In addition,with the increase of planting density,the accumulation of nitrogen,phosphorus and potassium nutrients in Helianthus tuberosus at all growth stages increased significantly;The amount of nutrient transport increased and the rate of nutrient transport decreased at flowering period;After anthesis,the nutrient transport and the nutrient transport rate showed an increasing trend.【Conclusion】Moderate planting can significantly increase tuber yield of Helianthus tuberosus,enhance the interception and utilization of light energy in plant canopy,and improve the absorption,storage and transport of nitrogen,phosphorus and potassium nutrients.Under the experimental conditions,the suitable planting density of Helianthus tuberosus was 3.15×10^(4)-3.30×10^(4) plants·hm^(-2).