孫東岳，許 輝，劉倩倩，許 波，吳兆晨，魏鳳珍，陳 翔**，李金才,2**

磷素后移對藥隔期倒春寒小麥旗葉光合及抗氧化系統(tǒng)的影響*

孫東岳1，許 輝1，劉倩倩1，許 波1，吳兆晨1，魏鳳珍1，陳 翔1**，李金才1,2**

（1.安徽農(nóng)業(yè)大學(xué)農(nóng)學(xué)院/農(nóng)業(yè)農(nóng)村部華東地區(qū)作物栽培科學(xué)觀測站，合肥 230036；2.江蘇省現(xiàn)代作物生產(chǎn)協(xié)同創(chuàng)新中心，南京 210095）

以抗倒春寒能力強(qiáng)的小麥品種“煙農(nóng)19”（YN19）和抗倒春寒能力弱的小麥品種“新麥26”（XM26）為供試材料，利用人工氣候箱開展盆栽低溫模擬實驗。實驗設(shè)置對照（日均氣溫15℃，夜間最低溫度11℃，CK）和低溫（?4℃，LT）兩個溫度處理，設(shè)置常規(guī)施磷（基肥:拔節(jié)肥為10:0，R1）和磷肥后移（基肥:拔節(jié)肥為5:5，R2）兩種施磷肥模式，低溫處理時長為4h·d?1。測定小麥開花期和灌漿期旗葉光合、抗氧化生理指標(biāo)及成熟期產(chǎn)量并進(jìn)行分析，以探明磷素后移對藥隔期倒春寒下小麥旗葉生長的緩解機(jī)理。結(jié)果表明：（1）LT處理較CK處理，供試兩品種旗葉葉綠素相對含量（SPAD值）、凈光合速率（Pn）、氣孔導(dǎo)度（Gs）、蒸騰速率（Tr）均顯著下降（P＜0.05），胞間CO2濃度（Ci）顯著上升。（2）LT處理與CK比較，供試兩品種旗葉抗氧化酶（SOD、CAT）活性顯著下降，丙二醛（MDA）含量顯著增加。（3）本實驗條件下，LT處理使供試兩品種穗粒數(shù)、千粒重及單莖產(chǎn)量較CK顯著降低。（4）LTR2與LTR1比較，XM26開花期和YN19灌漿期旗葉SPAD值分別顯著提高了7.3%和10.1%；XM26和YN19旗葉開花期的Pn顯著提高8.5%和16.2%，灌漿期顯著提高8.0%和8.7%，Gs、Tr和Ci影響差異不顯著。（5）LTR2與LTR1比較，XM26旗葉開花期和灌漿期SOD活性顯著提高9.0%和5.7%，CAT活性顯著提高12.4%和30.9%，MDA含量顯著降低7.9%和7.3%；YN19旗葉開花期和灌漿期SOD活性顯著提高7.7%和8.2%，CAT活性顯著提高20.8%和25.5%，MDA含量顯著降低6.8%和7.0%。（6）R2較R1顯著提高LT處理XM26的穗粒數(shù)8.4%，對兩品種千粒重?zé)o顯著影響，XM26和YN19單莖產(chǎn)量挽回率可達(dá)8.9%和9.9%。綜上所述，磷素后移可有效增強(qiáng)小麥旗葉細(xì)胞抗氧化能力，降低細(xì)胞膜脂過氧化程度，提高小麥旗葉的光合能力。通過抗氧化及光合能力兩方面協(xié)同緩解藥隔期倒春寒下小麥生育中后期旗葉生長狀況，增加主莖穗粒數(shù)和千粒重，保“源”增“庫”，達(dá)到無災(zāi)穩(wěn)產(chǎn)增產(chǎn)、有災(zāi)減損止損的效果。

倒春寒；磷素；小麥；光合；抗氧化系統(tǒng)

IPCC第六次報告指出，2011?2020年全球地表平均溫度較19世紀(jì)下半葉增長了1.09℃，預(yù)計21世紀(jì)末全球升溫幅度將超過1.5～2.0℃[1]。全球氣候變暖不僅導(dǎo)致極端低溫災(zāi)害事件頻發(fā)重發(fā)[2?4]，而且縮短了冬小麥越冬期，加速其生育進(jìn)程[5?7]，使其在遭遇春季低溫（倒春寒）時更易受到傷害[8]。小麥倒春寒（Late Spring Coldness in Wheat, LSCW）是指拔節(jié)?孕穗期遭遇突然低溫天氣，造成幼穗受傷或死亡，部分小穗不結(jié)實甚至全穗不結(jié)實，從而導(dǎo)致小麥減產(chǎn)的一種農(nóng)業(yè)氣象災(zāi)害[9]。黃淮麥區(qū)作為中國小麥主產(chǎn)區(qū)之一，3月中旬?4月上旬極易發(fā)生倒春寒，此時小麥幼穗處于雌雄蕊分化?藥隔形成期，是幼穗發(fā)育的低溫敏感期[10?11]。據(jù)報道，黃淮麥區(qū)倒春寒發(fā)生的年際頻率高達(dá)40%[12?13]，災(zāi)害嚴(yán)重年份受災(zāi)面積可達(dá)小麥播種面積的41.8%，產(chǎn)量損失可達(dá)50%以上。因此，研究倒春寒對黃淮麥區(qū)小麥生產(chǎn)的可持續(xù)高質(zhì)量發(fā)展具有重要意義。

關(guān)于小麥倒春寒災(zāi)害的致災(zāi)機(jī)理，前人從光合特性[14?16]、ROS代謝[10,17?18]、生物量積累[19?20]、蔗糖代謝[21]等方面進(jìn)行了大量研究。目前普遍認(rèn)為倒春寒災(zāi)害通過影響小麥源?庫器官的生長發(fā)育，進(jìn)而導(dǎo)致小麥減產(chǎn)[12]。在生產(chǎn)中應(yīng)用抗倒春寒品種、氮肥運籌、化控制劑是防控小麥倒春寒的有效措施，但通過磷肥運籌來防控小麥倒春寒的研究鮮有報道。磷素作為植物生長發(fā)育必需的大量元素之一，是植物體內(nèi)多種化合物諸如核酸、磷脂、ATP等的組成成分，同時承擔(dān)著植物體內(nèi)各種代謝和物質(zhì)運輸，比如碳水化合物的轉(zhuǎn)運與分配等[22]。合理施磷可緩解逆境脅迫給作物帶來的傷害，增強(qiáng)作物對逆境脅迫的抗性[23]。研究表明，適宜的磷肥施用量可提高葉片質(zhì)膜透性以及抗氧化能力來減緩低溫脅迫對葉片光合性能的影響，進(jìn)而增強(qiáng)植株的抗寒能力，緩解低溫對植株的傷害[24?25]。張政文等研究表明，在保證施磷總量的條件下，基肥和苗肥分施磷肥可提高油菜苗期的抗寒性，顯著增加產(chǎn)量[26]。盡管磷肥在不同作物低溫脅迫的調(diào)節(jié)中具有重要作用，但目前基于磷肥后移對藥隔期低溫下小麥葉片生長的調(diào)控機(jī)理尚不明確。

因此，本研究以兩種抗倒春寒能力強(qiáng)弱不同的小麥品種為實驗材料，設(shè)置磷肥全部基施和磷肥后移兩個施肥方式，通過人工氣候箱模擬大田倒春寒災(zāi)害，從旗葉光合特性及抗氧化特性方面進(jìn)行研究，以期明確磷肥后移對藥隔期倒春寒后小麥葉片生長的緩解作用，為黃淮麥區(qū)小麥倒春寒的防控提供理論依據(jù)。

1 材料與方法

1.1 實驗設(shè)計

實驗于2020年11月?2021年5月在安徽農(nóng)業(yè)大學(xué)農(nóng)萃園（31°86′N，117°26′E）進(jìn)行。選用抗倒春寒能力強(qiáng)的小麥品種煙農(nóng)19（YN19）和抗倒春寒能力弱的小麥品種新麥26（XM26）為供試材料。播種日期為2020年11月1日，采用盆栽種植，盆栽土壤取自農(nóng)萃園大田土壤0?20cm耕作層，土壤有機(jī)質(zhì)含量16.3g·kg?1，速效氮112.2mg·kg?1，速效磷23.0mg·kg?1，速效鉀161.6mg·kg?1。盆缽直徑為26cm，高度為35cm，每盆裝土8kg。每個處理12盆，每盆播種18粒，三葉期定苗，每盆定苗9株。全生育期每盆小麥?zhǔn)?.8g 尿素（基肥1.2g，拔節(jié)肥0.6g）、1.7g 硫酸鉀（基肥全施）。

實驗設(shè)置兩種磷肥施用方式：常規(guī)施磷（R1：每盆基肥施5g過磷酸鈣）和磷肥后移（R2：基肥和拔節(jié)肥每盆各施2.5g過磷酸鈣），設(shè)置兩個溫度水平：對照（CK）為大田常溫處理（處理當(dāng)日平均氣溫為15℃，夜間最低溫度為11℃）和低溫（LT）處理（DWGZ-1008型超低溫光照培養(yǎng)箱，?4℃）。以常溫下常規(guī)施磷為對照（即CKR1），其它分別為常溫下磷肥后移（即CKR2）、低溫下常規(guī)施磷（即LTR1）和低溫下磷肥后移（即LTR2）。通過顯微鏡觀察小麥幼穗分化時期，于藥隔期（2021年3月15日）1：00?5：00，每處理取10盆植株長勢基本一致的盆栽移入超低溫光照培養(yǎng)箱中進(jìn)行低溫處理，常溫處理均放在大田，當(dāng)日低溫處理結(jié)束后將盆栽原位埋回大田生長至成熟。小麥生育期田間管理同一般大田。

1.2 項目測定

1.2.1 葉片葉綠素相對含量（SPAD）

采用日本產(chǎn)SPAD-502型葉綠素計，于開花期（2021年4月13日）和灌漿期（2021年4月29日）每個處理隨機(jī)選取3株長勢一致的小麥標(biāo)記每株旗葉，測定葉片最寬處的SPAD值，求平均值作為該處理的葉片SPAD值。

1.2.2 葉片光合作用指標(biāo)

于開花期（2021年4月13日）和灌漿期（2021年4月29日），在晴天9：00?11：00，采用美國產(chǎn)CIRAS-3便攜式光合作用測定儀測定已標(biāo)記小麥旗葉的凈光合速率（Pn）、氣孔導(dǎo)度（Gs）、蒸騰速率（Tr）、胞間CO2濃度（Ci）等光合指標(biāo)，每個處理測定3張葉片。

1.2.3 葉片抗氧化系統(tǒng)指標(biāo)

于開花期（2021年4月13日）和灌漿期（2021年4月29日）各處理取3株長勢基本一致的小麥植株，取旗葉從葉片根部剪下，用液氮保存，帶回實驗室?80℃冰箱保存，用于生理生化指標(biāo)測定。超氧化物歧化酶（SOD）活性采用氮藍(lán)四唑法測定[27]。采用紫外吸收法測定過氧化氫酶（CAT）活性[27]。丙二醛（MDA）含量測定采用硫代巴比妥酸法[27]。

1.2.4 產(chǎn)量及其構(gòu)成因素

成熟期各處理選取3株長勢基本一致的小麥，測定穗粒數(shù)、單莖（主莖）產(chǎn)量以及千粒重。計算產(chǎn)量損失率及產(chǎn)量挽回率。

產(chǎn)量損失率計算式為

式中，RYL表示產(chǎn)量損失率（%），YT表示CKR2、LTR1和LTR2三個處理的單莖產(chǎn)量（g），YCK表示CKR1處理的單莖產(chǎn)量（g）。

產(chǎn)量挽回率計算式為

式中，RYR表示產(chǎn)量挽回率（%），YLTR1表示LTR1處理的單莖產(chǎn)量（g），YLTR2表示LTR2處理的單莖產(chǎn)量（g），YCK表示CKR1處理的單莖產(chǎn)量（g）。

1.3 數(shù)據(jù)處理

用Microsoft Excel 2019和OriginPro 2022進(jìn)行數(shù)據(jù)整理和作圖，用SPSS 26.0軟件進(jìn)行數(shù)據(jù)方差分析。

2 結(jié)果與分析

2.1 磷素后移對藥隔期倒春寒條件下小麥旗葉葉綠素相對含量的影響

由圖1可見，藥隔期倒春寒導(dǎo)致供試兩品種開花期和灌漿期旗葉葉綠素相對含量（SPAD）顯著減小，YN19品種R1和R2處理開花期分別下降7.8%和5.5%，灌漿期分別下降15.6%和 10.6%；XM26品種R1和R2處理開花期分別下降15.2%和9.2%，灌漿期分別下降29.1%和25.8%，可見抗倒春寒能力強(qiáng)的YN19下降幅度小于抗倒春寒能力弱的XM26。磷肥后移則顯著提高了XM26開花期和YN19灌漿期葉片的SPAD，分別增加7.3%和10.1%，對XM26灌漿期和YN19開花期的SPAD作用不顯著。結(jié)果表明磷肥后移有利于提高藥隔期遭遇倒春寒的抗倒春寒能力弱小麥品種（XM26）開花期和抗倒春寒能力強(qiáng)品種（YN19）灌漿期旗葉的葉綠素相對含量（SPAD）。

2.2 磷素后移對藥隔期倒春寒條件下小麥旗葉光合參數(shù)的影響

藥隔期倒春寒顯著影響供試兩品種旗葉在開花期和灌漿期的光合參數(shù)，其中Pn、Gs、Tr顯著下降，Ci顯著增加。磷肥后移顯著影響小麥旗葉Pn、Gs、Tr和Ci光合參數(shù)（圖2）。開花期LTR2處理與LTR1相比較，品種XM26的Pn顯著增加16.2%，對Gs、Tr和Ci影響差異不顯著；YN19的Pn、Tr分別顯著增加8.5%和18.7%，Ci顯著降低6.3%。灌漿期LTR2處理與LTR1相比較，品種XM26和YN19的Pn分別顯著增加8.0%和8.7%，對Gs、Tr和Ci影響差異不顯著。由此可見，磷肥后移可增加小麥生育中后期旗葉凈光合速率，緩解藥隔期倒春寒導(dǎo)致的光合能力下降，提高旗葉合成光合同化物的能力。

圖1 兩品種藥隔期倒春寒條件下不同磷肥處理開花期和灌漿期小麥旗葉SPAD的比較

注：小寫字母表示處理間在0.05水平上的差異顯著性。CKR1為大田常溫常規(guī)施磷處理，CKR2為大田常溫磷肥后移處理，LTR1為低溫下常規(guī)施磷處理，LTR2為低溫下磷肥后移處理。短線表示標(biāo)準(zhǔn)誤。下同。

Note: Lowercase letter indicates the difference significance among treatments at 0.05 leve. CKR1: conventional phosphorus fertilizer application under controlled temperature treatment; CKR2: phosphorus fertilizer postpone under controlled temperature treatment; LTR1: conventional phosphorus fertilizer application under low temperature treatment; LTR2: phosphorus fertilizer postpone under low temperature treatment. The bar is standard error. The same as below.

2.3 磷素后移對藥隔期倒春寒條件下小麥旗葉抗氧化酶活性和MDA含量的影響

由圖3可見，藥隔期倒春寒顯著降低供試兩品種開花期和灌漿期旗葉SOD和CAT活性。在兩溫度處理下，與R1相比，R2處理均能顯著增加兩個供試品種旗葉的SOD和CAT 活性。開花期LTR2處理與LTR1處理相比，品種XM26的SOD活性和CAT活性分別增加9.0%和12.4%，YN19的SOD活性和CAT活性分別增加7.7%和20.8%。灌漿期LTR2處理與LTR1處理相比較，品種XM26的SOD活性和CAT活性分別增加5.7%和30.9%，YN19的SOD活性和CAT活性分別增加8.2%和25.5%?？梢?，磷肥后移可提高小麥生育中后期旗葉的SOD和CAT活性，增強(qiáng)其清除活性氧的能力，降低了藥隔期倒春寒對旗葉造成的不利影響。

圖2 兩品種藥隔期倒春寒條件下不同磷肥處理開花期和灌漿期小麥旗葉光合參數(shù)的比較

圖3 兩品種藥隔期倒春寒條件下不同磷肥處理處理開花期和灌漿期小麥旗葉抗氧化酶活性的比較

由圖4可見，藥隔期倒春寒顯著增加供試兩品種開花期和灌漿期旗葉MDA含量，且MDA含量均表現(xiàn)為R2處理顯著低于R1處理。CKR2處理與CKR1處理相比較，品種XM26在開花期和灌漿期MDA含量分別減少6.8%和10.4%；品種YN19在開花期和灌漿期MDA含量分別減少7.0%和9.2%。LTR2處理與LTR1處理相比較，品種XM26開花期和灌漿期MDA含量分別減少7.9%和7.3%；YN19開花期和灌漿期MDA含量分別減少6.8%和7.0%。結(jié)果表明，磷肥后移可顯著降低旗葉MDA含量，緩解藥隔期倒春寒導(dǎo)致的細(xì)胞膜脂過氧化損傷，維持旗葉的持綠性，延緩旗葉衰老進(jìn)程。

圖4 兩品種藥隔期倒春寒條件下不同磷肥處理開花期和灌漿期小麥旗葉MDA含量的比較

Fig. 4 Comparison of MDA content in flag leaves of two wheat varieties at flowering and filling stages under late spring coldness at connectivun stage with different phosphorus fertilizer treatments

2.4 磷素后移對藥隔期倒春寒條件下小麥產(chǎn)量及其構(gòu)成因素的影響

由表1可見，與CK相比，藥隔期倒春寒顯著降低兩個供試品種穗粒數(shù)、千粒重和單莖產(chǎn)量。其中，品種XM26在R1和R2處理下產(chǎn)量損失率分別為52.79%和48.07%，YN19在R1和R2處理下產(chǎn)量損失率分別為44.30%和39.91%。與CKR1相比，CKR2處理下XM26和YN19的穗粒數(shù)分別增加3.5%和3.7%，千粒重分別增加4.3%和0.4%。LTR2處理與LTR1處理相比較，品種XM26和YN19的穗粒數(shù)分別增加8.4%和2.0%，千粒重分別增加1.8%和7.0%。磷肥后移有利于提高產(chǎn)量挽回率，品種XM26和YN19的產(chǎn)量挽回率分別為8.94%和9.90%。實驗結(jié)果表明，磷肥后移有利于提高小麥穗粒數(shù)和千粒重，從而緩解藥隔期倒春寒對小麥產(chǎn)量造成的損失。

3 結(jié)論與討論

3.1 討論

低溫脅迫會誘導(dǎo)植物細(xì)胞產(chǎn)生大量的活性氧自由基（ROS），ROS過量積累與脂質(zhì)發(fā)生過氧化反應(yīng)產(chǎn)生膜脂過氧化產(chǎn)物丙二醛（MDA），其含量間接反映細(xì)胞膜脂過氧化程度[28?29]。ROS可通過抗氧化酶系統(tǒng)來清除，SOD是清除OH?的重要酶之一，反應(yīng)生成的部分H2O2由CAT分解最終生成H2O和O2，使膜系統(tǒng)免受過氧化傷害[30]。前人研究表明，低溫脅迫可提高拔節(jié)期小麥功能葉抗氧化酶活性，但仍會增加MDA含量[31]。以往研究大多集中在低溫處理后葉片即時的響應(yīng)機(jī)制，對低溫后小麥生育中后期旗葉的生長狀況研究甚少。本實驗結(jié)果顯示，藥隔期低溫處理導(dǎo)致供試兩品種開花期和灌漿期旗葉SOD和CAT活性顯著低于對照處理，MDA含量顯著高于對照處理，表明藥隔期低溫抑制了小麥生育中后期旗葉的抗氧化酶系統(tǒng)活性，導(dǎo)致大量MDA積累，使膜系統(tǒng)受損。同時，XM26旗葉MDA含量在兩生育時期明顯高于YN19，表明XM26 旗葉膜系統(tǒng)受損程度高于YN19，說明抗倒春寒能力強(qiáng)的小麥品種在生育中后期旗葉生長狀況優(yōu)于抗倒春寒能力弱的品種。

表1 兩品種藥隔期倒春寒條件下不同磷肥處理小麥產(chǎn)量及其構(gòu)成因素的比較

注：表中數(shù)據(jù)為平均值±標(biāo)準(zhǔn)差（n=3）。小寫字母表示處理間在0.05水平上的差異顯著性。

Note: Data are mean±standard deviation (n=3). Lowercase indicates the difference significance among treatments at 0.05 level. TGW is thousand grains weight, SSY is single stem yield, YLR is yield loss rate, YRR is yield recovery rate.

有學(xué)者指出，低溫條件下施磷可顯著提高植物葉片抗氧化酶活性[32]，顯著減少MDA含量[33]。以往研究發(fā)現(xiàn)，基肥和苗肥施用充足的磷肥可有效增加油菜苗期葉片的CAT活性，提高苗期油菜的抗凍能力[26]。本研究結(jié)果與前人結(jié)果基本一致，無論常溫還是低溫，磷肥后移均可顯著提高供試兩品種旗葉SOD和CAT活性，降低其MDA含量。表明磷肥后移可有效提高藥隔期低溫處理后小麥生育中后期旗葉的抗氧化酶活性，增強(qiáng)ROS清除能力，從而有效降低旗葉細(xì)胞膜脂過氧化程度，緩解低溫脅迫帶來的生長損傷，從而保證小麥“源”器官的生理活性。

旗葉作為小麥生育中后期最重要的功能葉，其光合作用是小麥籽粒灌漿的碳同化來源主要途徑以及小麥產(chǎn)量形成的依賴因素[34]，但光合作用對溫度變化的響應(yīng)非常敏感[35?36]。王瑞霞等研究表明，春季低溫脅迫導(dǎo)致小麥葉片葉綠素含量、Pn、Tr和Gs均呈降低趨勢，Ci則較大幅度升高[15]。本實驗結(jié)果顯示，藥隔期低溫處理后，供試兩品種旗葉在開花期和灌漿期的SPAD值顯著降低，其中灌漿期降幅大于開花期，抗倒春寒能力弱的品種XM26降幅大于抗倒春寒能力強(qiáng)的品種YN19。這說明前期低溫處理影響了小麥生育中后期旗葉的持綠性，對抗倒春寒能力弱的品種損傷更加嚴(yán)重。藥隔期低溫處理后，供試兩品種旗葉在開花期和灌漿期Pn、Gs、Tr均顯著減小，Ci顯著增加，這與前人研究結(jié)果相似[15,18]。Pn和Gs下降的同時，Ci顯著增加，表明光合速率的下降是非氣孔因素導(dǎo)致的[37]。以上結(jié)果的原因可能是藥隔期低溫處理減弱了小麥旗葉的生理活性，抗氧化酶活性的下降和MDA的積累導(dǎo)致葉肉細(xì)胞膜組織破壞，葉綠體結(jié)構(gòu)受損，從而導(dǎo)致旗葉葉綠素含量減少，光合性能下降。

作為光合作用主要媒介之一，充足的磷可以增加植物葉片葉綠素含量，提高葉片Pn[25]。本實驗結(jié)果顯示，磷肥后移僅顯著提高了CK處理下YN19開花期和LT處理下XM26開花期、YN19灌漿期旗葉的SPAD，這可能是由于品種特性不同導(dǎo)致磷肥后移作用時期不同。本實驗還表明，藥隔期低溫處理后，磷肥后移顯著提高供試兩品種旗葉開花期和灌漿期的Pn，對Gs、Tr和Ci無顯著影響，說明磷肥后移主要通過緩解非氣孔因素來提高小麥旗葉光合速率。因此，磷肥后移可增加小麥生育中后期旗葉葉綠素含量，提高凈光合速率，從而增強(qiáng)旗葉光合能力，為穗部干物質(zhì)積累、轉(zhuǎn)運及分配提供“源”動力。

藥隔期低溫主要通過減少葉片向穗部的干物質(zhì)轉(zhuǎn)運，使穗部發(fā)育受阻，結(jié)實率下降，最終導(dǎo)致產(chǎn)量下降[11]。張金恩等研究表明，低溫脅迫解除后水稻由于光合產(chǎn)物運輸受阻，產(chǎn)量顯著下降[38]?？骆骆碌妊芯恐赋?，低溫脅迫嚴(yán)重影響小麥干物質(zhì)的積累、轉(zhuǎn)運及分配，抑制了小麥上部小穗的生長發(fā)育，導(dǎo)致產(chǎn)量降低[11,39]。還有研究表明，低溫條件下小麥產(chǎn)量下降的原因主要是穗粒數(shù)的減少[40?41]。本實驗條件下，藥隔期低溫處理導(dǎo)致小麥主莖穗粒數(shù)、千粒重和產(chǎn)量顯著減少，這與岳俊芹等的研究結(jié)果相似[42]。此外，YN19的產(chǎn)量損失率低于XM26，表明藥隔期低溫后小麥減產(chǎn)程度與品種抗倒春寒能力強(qiáng)弱相關(guān)。

磷素可直接參與小麥光合同化，促進(jìn)干物質(zhì)積累與轉(zhuǎn)運，有利于籽粒建成，增加產(chǎn)量[43]。本實驗結(jié)果顯示，磷肥后移主要通過增加XM26穗粒數(shù)和YN19千粒重來減少產(chǎn)量損失。表明磷肥后移主要通過提高穗部結(jié)實性來緩解藥隔期低溫對抗倒春寒能力弱的品種產(chǎn)量的影響，而對于抗倒春寒能力強(qiáng)的品種則主要提高其粒重來緩解產(chǎn)量損失。

限于盆栽實驗條件等因素的影響，無法基于大田小麥苗情及土壤墑情研究倒春寒。且目前針對磷肥后移對小麥生長的緩解作用機(jī)理僅限于葉片和表層生理的研究，未來還需對小麥其他生長部位并朝著分子生物學(xué)方向進(jìn)行深度考究，從而更系統(tǒng)、更有深度地闡明磷肥后移緩解小麥藥隔期倒春寒危害的機(jī)理，為磷肥后移防控小麥倒春寒提供堅實的理論支撐。

3.2 結(jié)論

（1）藥隔期倒春寒會減弱小麥開花期和灌漿期旗葉的生理活性，減少葉綠素含量，降低凈光合速率，最終減少主莖的穗粒數(shù)和千粒重，導(dǎo)致產(chǎn)量損失嚴(yán)重。

（2）磷肥后移可提高小麥旗葉抗氧化酶活性，減少MDA積累，降低細(xì)胞膜脂過氧化程度，從而維持ROS平衡，提高葉片生理活性；進(jìn)而提高旗葉的SPAD和Pn，維持較高的光合能力，以此提高穗部穗粒數(shù)和千粒重，減少產(chǎn)量損失。

（3）與常規(guī)“一炮轟”施磷方式相比，磷肥后移增加抗倒春寒能力強(qiáng)的品種YN19的粒重，緩解藥隔期倒春寒導(dǎo)致的產(chǎn)量損失；對于倒春寒能力弱的品種XM26則通過提高其穗部結(jié)實率，可挽回一定產(chǎn)量損失。因此，磷肥后移可作為黃淮麥區(qū)小麥生產(chǎn)中防控倒春寒災(zāi)害的有效措施。

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Effects of Phosphorus Fertilizer Postpone on Photosynthesis and Antioxidant System of Wheat Flag Leaves under Late Spring Coldness at Connectivum Stage

SUN Dong-yue1, XU Hui1, LIU Qian-qian1, XU Bo1, WU Zhao-chen1, WEI Feng-zhen1, CHEN Xiang1, LI Jin-cai1,2

(1. College of Agronomy, Anhui Agricultural University/Crop cultivation Science Observatory in East China of the Ministry of Agriculture and Rural Affairs，Hefei 230036, China；2.Collaborative Innovation Center of Modern Crop Production in Jiangsu, Nanjing 210095)

In order to explore the alleviating mechanism of phosphorus fertilizer postpone on the growth of wheat flag leaves under late spring coldness at connectivum stage, the low temperature simulation experiment of pot was carried out by using the artificial climate chamber with the wheat variety "Yannong 19" (YN19, strong resistance to reversed late spring coldness) and the wheat variety "Xinmai 26" (XM26 weak resistance to reversed late spring coldness) as experimental materials. In the experiment, two temperature treatments were set at connectivum stage of wheat: control(average daily temperature 15℃, minimum night temperature 11℃, CK) and low temperature(?4℃, LT), and two phosphorus fertilizer application modes: conventional phosphorus fertilizer application which all of phosphorus fertilizer was applied as base fertilizer and phosphorus fertilizer postpone which half of phosphorus fertilizer was applied as jointing fertilizer. The low temperature treatment lasted for 4h·d?1. Photosynthetic and antioxidant physiological indices of flag leaves at flowering and grain filling stage and yield were analyzed. The results showed as follows: (1) compared with CK, the relative chlorophyll content (SPAD value), net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of flag leaves in LT treatment significantly decreased(P<0.05), while the intercellular CO2concentration (Ci) significantly increased. (2) Compared with CK, LT treatment significantly decreased the activities of SOD and CAT, and significantly increased the content of malondialdehyde (MDA). (3) Under the experimental conditions, LT treatment significantly reduced the number of grains per spike, 1000 grains weight and single stem yield of the two varieties compared with CK treatment. (4) Compared with LTR1, the SPAD value of XM26 flag leaves at flowering stage and YN19 flag leaves at grain filling stage under LTR2 treatment were significantly increased by 7.3% and 10.1%, respectively. Pn of XM26 and YN19 flag leaves was significantly increased by 8.5% and 19.0% at flowering stage, 8.0% and 8.7% at grain filling stage, and there was no significant difference in Gs, Tr and Ci. (5) Compared with LTR1, SOD activity, CAT activity and MDA content of XM26 flag leaves at flowering and grain filling stages of LTR2 in were significantly increased by 9.0% and 5.7%, 12.4% and 30.9%, and 7.9% and 7.3%, respectively; SOD activity, CAT activity and MDA content of YN19 flag leaves at flowering and grain filling stages of LTR2 were significantly increased by 7.7% and 8.2%, 20.8% and 25.5%, and 6.8% and 7.0%, respectively. (6) Compared with R1, R2 significantly increased the grain number per spike of XM26 by 8.4% after LT treatment, but had no significant effect on the 1000 grains weight of the two cultivars. The yield recovery rates of XM26 and YN19 per stem could reach 8.9% and 9.9%. In conclusion, delayed phosphorus transfer can effectively enhance the antioxidant capacity of wheat flag leaf cells, reduce the degree of membrane lipid peroxidation, and improve the photosynthetic capacity of wheat flag leaf cells. Through the synergistic alleviation of antioxidant and photosynthetic capacity, the growth of flag leaves in the middle and late stage of wheat growth under reversed late spring coldness at connectivum stage, the number of grains per spike and 1000 grains weight of main stem were increased, the "source" was maintained and the "reservoir" was increased, and the effects of disaster free, stable and increased yield, disaster reduction and loss stopping were achieved.

Late spring coldness; Phosphate; Wheat; Photosynthetic; Antioxidant system

10.3969/j.issn.1000-6362.2023.02.004

孫東岳,許輝,劉倩倩,等.磷素后移對藥隔期倒春寒小麥旗葉光合及抗氧化系統(tǒng)的影響[J].中國農(nóng)業(yè)氣象,2023,44(2):123-132

收稿日期：2022?03?10

安徽省自然科學(xué)基金(2008085QC122)；安徽省重大科技專項（202003b06020021）；淮北市重大科技專項（HK2021013）；“十四五”安徽省現(xiàn)代農(nóng)業(yè)產(chǎn)業(yè)技術(shù)體系建設(shè)專項資金；安徽省大學(xué)生創(chuàng)新創(chuàng)業(yè)訓(xùn)練計劃（S202110364291）

通訊作者：李金才，教授，博士生導(dǎo)師，研究方向為作物生理生態(tài)，E-mail:ljc5122423@126.com；陳翔，講師，碩士生導(dǎo)師，研究方向為作物生理生態(tài)，E-mail:cxagricultural@163.com

孫東岳，E-mail: ahausdy@stu.ahau.edu.cn