磷供应水平对大豆不同生育期磷铁比及光合效率的调节

Regulatory effect of phosphorus rate on the photosynthetic efficiency and P/Fe ratio in soybean

【目的】明确磷(P)不同供应水平对大豆生理性状的影响及其基因型差异,以及这些性状对单株粒重的影响,为磷肥的合理施用提供理论依据。【方法】水培试验以Hoagland营养液为基础,设置4个磷供应水平处理,分别为0 (CK)、100、500和1000μmol/L。供试大豆为6个磷高效基因型和6个磷低效基因型。在大豆生长的始花期、结荚初期测定叶片光合性能和磷、铁浓度,在成熟期测定籽粒磷铁含量及单株籽粒重。对光合性能数据与铁、磷浓度进行典型相关性分析,利用单株粒重建立逐步回归方程并进行通径分析。【结果】CK处理的磷高效和磷低效基因型大豆植株在始花期的初始荧光(Fo)值极显著高于其他处理;P 100μmol/L处理极显著提高了两类基因型大豆始花期的PSⅡ实际光化学效率(Φ_(PSⅡ)),有助于提高其光能转化率,因而单株粒重均较高。相比于P 100μmol/L处理,磷高效和磷低效基因型大豆结荚初期叶片中的铁浓度及其铁/磷值都随着磷供应量的增大而降低。相比于P 100μmol/L处理,P 500和1000μmol/L处理下,磷高效基因型单株粒重并没有显著上升,而磷低效基因型单株粒重则下降。此外,结荚初期两个基因型大豆叶片的SPAD值在P 100μmol/L处理下达到峰值,鼓粒初期叶片SPAD值与磷高效和磷低效基因型大豆单株粒重均有正效应。【结论】磷供应水平影响大豆叶片中的P/Fe值,进而影响着叶片光合效率。无论磷高效还是低效基因型大豆品种,较低的磷供应水平(100μmol/L)可调节始花、结荚初期和鼓粒期的叶绿素含量,进而调控代谢过程有利于最终籽粒的形成。过高的磷供应水平无益于大豆单株粒重的增加,还可能产生负作用。

【Objectives】This study investigated the effects of different P supply levels on physiological traits and seed yield of soybean genotypes with different P efficiencies.【Methods】A hydroponic experiment was carried out,using six P-efficient and six P-inefficient genotypes of soybean as test materials.Based on the Hoagland nutrient solution,the P concentration was adjusted into four levels:0(CK),100,500 and 1000μmol/L.The photosynthetic characteristics,P/Fe ratio in soybean leaves were determined at early flowering and early podding stages.The seed weight and contents of P and Fe were measured at seed filling stage(R8).Canonical correlation analysis between photosynthetic characteristics and P/Fe ratio was carried out,and stepwise regression equation was established by seed weight per plant,then pathway analysis was performed.【Results】Whether in P-efficient or inefficient genotypes,0μmol/L of P resulted in a dramatic increase(P<0.01)in Fo value at early flowering stage;100μmol/L P supply treatment significantly improves actual photochemical efficiency of PSⅡ(Φ_(PSⅡ))at early flowering stage,which improved the light energy conversion rate,and under this treatment,seed weights per plant of both P-efficient and P-inefficient genotypes were higher.Compared with P 100μmol/L treatment,both Fe concentration and Fe/P ratio of leaf at early podding stage exhibited a decreasing trend with increasing P supply level.Compared with treatment of P 100μmol/L,the seed weight per plant of P-efficient genotypes did not increase significantly at P supply of 500 and 1000μmol/L,but seed weight per plant of Pinefficient genotypes decreased.In addition,SPAD values at early podding attained peaks under P 100μmol/L treatment,and the SPAD value at seed filling stage stage had a positive correlation with seed weight per plant of both P-efficient and inefficient genotypes.【Conclusions】P supply level affects photosynthetic efficiency as well as P/Fe ratio in soybean leaves.Normal P supply level(100μmol/L)could regulate the chlorophyll content at the early flowering,early podding and seed filling stage,and then regulate the metabolic process,which is beneficial to grain formation in both P-efficient and P-inefficient genotypes.High P supply does not result in substantial increase in seed weight,but may result in a negative effect on seed weight.