摘要：

为了探讨干旱和品种对小麦灌浆期旗叶下午净光合速率(Pn)、光合关键酶活性和产量的影响,2019—2021年度在池栽全生育期遮雨条件下设置包括重度(W1)、中度(W2)、轻度(W3)干旱和适墒(W4)的4个水分处理,在灌浆前期、中期的14:00—16:00测定了强抗旱性品种晋麦47(JM47)和弱抗旱性品种偃展4110(YZ4110)的旗叶Pn、1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)、Rubisco活化酶(RCA)、ATP合成酶(ATPase)、磷酸烯醇式丙酮酸羧化酶(PEPC)和丙酮酸磷酸双激酶(PPDK)活性以及成熟期的产量。结果表明,干旱使小麦灌浆期旗叶下午Pn、多数光合酶活性以及产量降低,总体表现为干旱胁迫程度越大,上述指标的降幅也越大,但其影响效应存在品种和年际差异。W1、W2和W3与W4相比,旗叶下午Pn,JM47分别降低33.6%~40.6%,12.0%~30.5%和5.0%~13.5%,YZ4110分别降低44.0%~52.0%,22.5%~38.1%和11.5%~20.5%;旗叶下午Rubisco活性,JM47灌浆前期降低、灌浆中期增加,而YZ4110分别降低13.3%~25.6%,7.1%~14.0%和11.2%~11.6%;旗叶下午RCA活性,灌浆前期多显著降低,灌浆中期JM47在W2和W3下增加,而 YZ4110在W1和W2下降低;旗叶下午ATPase活性,JM47在W1下降低、W3下提高,而YZ4110分别降低19.3%~48.7%,7.2%~24.2%和0.1%~8.9%。不同水分处理的旗叶下午PEPC活性因生长季和品种而异,但W1与W4相比,JM47和YZ4110的旗叶下午PPDK活性分别降低12.4%~18.8%和16.7%~18.2%。与YZ4110相比,JM47旗叶下午Pn和光合酶活性在适墒下多无显著差异,但干旱下多表现为升高。相关性分析结果表明,产量、旗叶下午Pn与灌浆期旗叶下午ATPase活性和灌浆前期旗叶下午PEPC活性呈极显著正相关,因而在灌浆期下午保持较高的旗叶ATPase和PEPC活性有利于提高小麦旗叶下午Pn和籽粒产量。

关键词: 小麦, 干旱, 品种, 灌浆期, 旗叶, 光合酶

Abstract:

To clarify the effects of drought stress and cultivars on the net photosynthetic rate(Pn),the activities of photosynthetic enzymes in flag leaf in the afternoon(FLA)during grain filling stage and grain yield of winter wheat,a pond culture experiment with four water levels and two winter wheat cultivars was conducted under the condition of rainproof pond cultivation in 2019—2021.The four water treatments included severe drought(W1),moderate drought(W2),mild drought(W3),and suitable water supply(W4).The Pn,and the activities of Rubisco,RCA,PEPC,ATPase and PPDK in flag leaf from 14:00 to 16:00 during the early(EGFS)and medium(MGFS)grain filling stage,and the grain yield at maturity of strong drought resistance cultivar Jinmai 47(JM47)and weak drought resistance cultivar Yanzhan 4110(YZ4110)were investigated.Drought stress decreased the FLA Pn and activities of most photosynthetic enzymes,and the grain yield of wheat.The decrease of these indexes increased with drought stress degree,but the effects were different among varieties and years.Compared with W4,the FLA Pn of JM47 under W1,W2 and W3 decreased by 33.6%—40.6%,12.0%—30.5% and 5.0%—13.5%,as well as YZ4110 decreased by 44.0%—52.0%,22.5%—38.1% and 11.5%—20.5%,respectively.Compared with W4,the FLA Rubisco activity decreased during EGFS but increased during MGFS for JM47,while it decreased by 13.3%—25.6%,7.1%—14.0% and 11.2%—11.6% for YZ4110,respectively,under W1,W2 and W3.Compared with W4,the FLA RCA activity significantly decreased under most drought treatments during EGFS,while increased under W2 and W3 for JM47 and decreased under W1 and W2 for YZ4110 during MGFS.Compared with W4,the FLA ATPase activity of JM47decreased under W1 but increased under W3,while that of YZ4110 decreased under W1,W2 and W3 by 19.3%—48.7%,7.2%—24.2% and 0.1%—8.9%,respectively.The FLA PEPC activity under different treatments varied with growing seasons and varieties.Compared with W4,the FLA PPDK activities of JM47 and YZ4110 under W1 were decreased by 12.4%—18.8% and 16.7%—18.2%.Compared with YZ4110,in most conditions,the FLA Pn and photosynthetic enzyme activities of JM47 had no significant difference under suitable water supply(W4),but increased under drought treatments(W1,W2 and W3).The results of correlation analysis showed that yield,FLA Pn were significantly positively correlated to FLA ATPase activity during EGFS and MGFS,as well as FLA PEPC activity during EGFS.Thus,increasing the FLA ATPase and PEPC activities during the grain filling period is conducive to the increase of FLA Pn and grain yield of wheat.

Key words: Wheat, Drought, Cultivars, Grain filling period, Flag leaf, Photosynthetic enzyme