遮荫对滨海盐碱地水盐运移及油葵生长和生理的影响

Effects of shading on soil water and salt transport of coastal saline⁃alkali land and Helianthus annuus Linn.growth and physiology

盐碱地是建设光伏的主要土地类型之一。盐碱地光伏系统中光伏组件的遮荫作用会改变局地微气候进而影响土壤水盐动态,系统内作物的生长会受到遮荫和土壤盐分的双重胁迫,阐明遮荫下盐碱地水盐动态和作物生理响应对指导盐碱地光伏农业开发利用具有重要意义。采用大田试验方法,以油葵(Helianthus annuus Linn.)为试验对象,分别设0%、30%、60%和90%遮荫水平,探究遮荫对滨海盐碱地水盐动态及油葵生长特性、光合特性、叶片解剖结构、生物量、籽粒产量及品质的影响,以揭示遮荫下滨海盐碱地水盐运移规律及作物生长和生理变化。结果表明,与无遮荫相比,遮荫能够显著增加滨海盐碱地油葵全生育期内土壤剖面含水量,降低土壤剖面含盐量。遮荫会显著降低油葵净光合速率,抑制茎粗和花盘的生长,减少籽粒粗脂肪,并提高籽粒粗蛋白。弱光下油葵自身会通过增加株高、提高光合色素含量、降低光合色素比值、提高光合酶活性、减小叶片厚度、改变碳同化产物分配方向等方式来促进光合作用。在遮荫率约为30%—60%时,能够增加18%—38%的耕作层土壤含水量,降低6%—18%的耕作层土壤含盐量,并维持15%—38%的油葵生物量和29%—55%的油葵籽粒产量。以上结果表明,遮荫能够改善滨海盐碱地水盐条件,减轻作物盐胁迫,但油葵作为喜光作物,遮荫会显著抑制其光合作用,影响籽粒产量和品质,因此,建议在光伏组件上限遮荫率约为30%—60%的盐碱地光伏系统内种植油葵,以维持油葵的籽粒产量。

Saline-alkali land is one of the main land types for photovoltaic construction.In saline-alkali land photovoltaic system,the shading effect of photovoltaic modules affects soil water and salt dynamics by changing the microclimate,and crop growth is affected by both shading and soil salinity.The study of soil water and salt dynamics and physiological response of crops in saline-alkali land under shading has an important guiding significance for the development and utilization of saline-alkali land photovoltaic agriculture.In this study,Helianthus annuus Linn.,a salt-tolerant and light-loving crop,was taken as the research object.The field experiment with four shading levels(0%,30%,60%and 90%shading)was designed to explore the effects of shading on the soil moisture content and soil salt content in 0—60 cm soil layer and the height,stem diameter,disc diameter,single-leaf area,leaf photosynthetic gas exchange parameters,leaf photosynthetic pigment content,leaf photosynthetic enzyme activity,leaf anatomical structure,biomass,grain yield and grain quality of Helianthus annuus Linn.in coastal saline-alkali land,revealing the law of soil water and salt transport and crop growth and physiological changes in coastal saline-alkali land under shading.The results showed that the shading significantly increased the soil profile water content and decreased the soil profile salt content during the whole growth period of Helianthus annuus Linn.in coastal saline-alkali land,compared with no shading.Shading decreased the net photosynthetic rate,inhibited the growth of stem and flower disc,decreased crude fat content and increased crude protein content of Helianthus annuus Linn.Under low light,Helianthus annuus Linn.promoted photosynthesis by increasing plant height,increasing leaf photosynthetic pigment content,decreasing leaf photosynthetic pigment ratio,increasing the enzyme activities of ribulose-1,5-diphosphate carboxylase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC)in leaves,reducing leaf thickness,and changing the allocation direction of carbon assimilation product.At the shading rate of about 30%—60%,it was able to increase the soil water content of the tillage layer by 18%—38%,reduce the soil salt content of the tillage layer by 6%—18%,and maintain 15%—38%biomass and 29%—55%grain yield of Helianthus annuus Linn.The above results indicated that shading could improve the water and salt conditions of coastal saline-alkali land and alleviate the salt stress of crops,but Helianthus annuus Linn.as a light-loving crop,shading could inhibit its photosynthesis and affect its grain yield and quality.Therefore,it is recommended to plant Helianthus annuus Linn.in saline-alkali land photovoltaic system with the upper shading rate of photovoltaic modules of about 30%—60%to maintain grain yield.