徐沁怡 王 標(biāo) 趙建文 吳建峰 曹亦潤(rùn) 楊先有 夏國(guó)華 王正加 黃堅(jiān)欽 胡淵淵
(浙江農(nóng)林大學(xué)亞熱帶森林培育國(guó)家重點(diǎn)實(shí)驗(yàn)室培育基地 臨安 311300)
2種花粉授粉山核桃果皮光合特性的差異比較*
徐沁怡 王 標(biāo) 趙建文 吳建峰 曹亦潤(rùn) 楊先有 夏國(guó)華 王正加 黃堅(jiān)欽 胡淵淵
(浙江農(nóng)林大學(xué)亞熱帶森林培育國(guó)家重點(diǎn)實(shí)驗(yàn)室培育基地 臨安 311300)
【目的】 研究授不同花粉的山核桃果實(shí)發(fā)育期間外果皮光合速率、光合色素及葉綠素?zé)晒馓匦缘淖兓接懟ǚ凼诜蹖?duì)山核桃外果皮光合特性的影響,以及其與果實(shí)干物質(zhì)形成的關(guān)系,初步揭示花粉直感使山核桃果實(shí)增大的光合生理機(jī)制,為探尋進(jìn)一步提高山核桃產(chǎn)量的技術(shù)路徑提供參考依據(jù)?!痉椒ā?設(shè)置2種授粉組合[山核桃×山核桃(hp)和山核桃×薄殼山核桃(pp)],于授粉后不同天數(shù)測(cè)定2種花粉授粉山核桃果實(shí)的光合面積、干質(zhì)量、光合速率、光合色素及葉綠素?zé)晒馓匦缘淖兓??!窘Y(jié)果】 1) 薄殼山核桃花粉(pp)授粉的山核桃果實(shí)顯著大于山核桃花粉 (hp) 授粉的果實(shí),且外果皮顏色更綠。果實(shí)發(fā)育前期(授粉后50~73天)和后期(授粉后103~120天),pp授粉果實(shí)表面積和干質(zhì)量的日增量均顯著高于hp授粉果實(shí)。授粉后50~85天,pp授粉果實(shí)的光合速率顯著高于hp果實(shí)。2種花粉授粉山核桃果實(shí)的干質(zhì)量日均增量與其單果的光合速率日均增量之間呈顯著相關(guān)。2) 果實(shí)發(fā)育過程中,pp授粉果實(shí)的葉綠素含量顯著高于hp果實(shí),且果實(shí)的葉綠素含量與其外果皮的光合速率呈顯著相關(guān)。3) 在一定光強(qiáng)(1 265 μmol·m-2s-1)下,pp授粉果實(shí)的實(shí)際光化學(xué)效率(Y)、表觀電子傳遞速率(ETR)和光化學(xué)猝滅系數(shù)(qP)均顯著高于hp授粉果實(shí)。果實(shí)發(fā)育過程中,hp授粉果實(shí)外果皮ETR達(dá)到峰值的光強(qiáng)強(qiáng)度顯著低于pp授粉果實(shí)外果皮ETR達(dá)到峰值的光強(qiáng)強(qiáng)度,且在果實(shí)發(fā)育后期(授粉后103~120天),hp授粉果實(shí)外果皮ETR達(dá)到峰值的光強(qiáng)強(qiáng)度顯著降低,下降幅度約為50%。在果實(shí)發(fā)育后期(授粉后103~120天),hp授粉果實(shí)外果皮的Y(NO)顯著增加,pp授粉果實(shí)外果皮的Y(NO)無明顯變化; 且在授粉后120天,與hp授粉果實(shí)外果皮相比,pp授粉果實(shí)外果皮具有較高的Y(Ⅱ)和較低的Y(NO)?!窘Y(jié)論】 授粉后50~73天,pp授粉的山核桃果實(shí)干質(zhì)量快速增加主要是由于其較大的光合面積和較高的光合速率; 授粉后103~120天,pp授粉果實(shí)干質(zhì)量快速增加主要是由于其較大的光合面積。果實(shí)發(fā)育后期(授粉后103~120天),hp授粉的果實(shí)較易受到光損傷,而pp授粉的果實(shí)具有較強(qiáng)的抗光抑制能力,這可能是pp授粉果實(shí)生物量增加的重要原因。關(guān)鍵詞: 山核桃; 外果皮; 氣體交換參數(shù); 葉綠素?zé)晒猓?物質(zhì)生產(chǎn)
胡桃科(Juglandaceae)山核桃屬(Carya)有2種普遍栽培的經(jīng)濟(jì)樹種: 山核桃(Caryacathayensis)和薄殼山核桃(C.illinoensis)。前者我國(guó)特有,味香殼厚; 而后者原產(chǎn)美國(guó),殼薄味濃。通過不同的授粉試驗(yàn),山核桃具有明顯的花粉直感現(xiàn)象(葉茂富等, 1965; 王正加等, 2010; 葉浩然等, 2013)。授薄殼山核桃花粉的山核桃果實(shí)外果皮變綠,果實(shí)、種仁明顯增大,但分子標(biāo)記顯示授粉子代與母本遺傳基礎(chǔ)無明顯差異(王正加等, 2010),這表明果實(shí)變異不是由于遺傳物質(zhì)變化引起的,果實(shí)的大小和發(fā)育主要受從葉片及其他非葉光合器官(如綠色果皮)運(yùn)輸而來的光合產(chǎn)物影響(Cocaliadisetal., 2014)。雖然葉片是植物主要的光合器官,但許多植物的果實(shí)也含有葉綠素,能進(jìn)行光合作用,且對(duì)果實(shí)或種子的形成具有重要貢獻(xiàn)(Lytovchenkoetal., 2011; Huetal., 2012),是對(duì)葉片光合物質(zhì)生產(chǎn)能力的有效補(bǔ)充(Paveletal., 1993; Marcelisetal., 1995; Hetheringtonetal., 1998)。
本研究設(shè)置2種授粉組合:山核桃×山核桃(hp)和山核桃×薄殼山核桃(pp),研究授不同花粉的山核桃果實(shí)發(fā)育期間外果皮光合速率、光合色素及葉綠素?zé)晒馓匦缘淖兓?,探討花粉授粉?duì)山核桃外果皮光合特性的影響,以及其與果實(shí)干物質(zhì)形成的關(guān)系,初步揭示花粉直感使山核桃果實(shí)增大的光合生理機(jī)制。通過研究山核桃外果皮的光合增產(chǎn)潛力和優(yōu)勢(shì),為探尋進(jìn)一步提高山核桃產(chǎn)量的技術(shù)途徑提供參考依據(jù)。
1.1 試驗(yàn)地概況
試驗(yàn)地位于浙江農(nóng)林大學(xué)山核桃試驗(yàn)林基地(30°14′10.68″E,119°43′11.63″N)。該基地地勢(shì)平緩, 2008年采用嫁接苗造林,砧木為2年生湖南山核桃,穗條為1年生山核桃品種, 2012年開始結(jié)果。每年4月花期時(shí)施少量復(fù)合肥,9月果實(shí)采收后施有機(jī)肥,田間栽培技術(shù)措施基本相同。
1.2 試驗(yàn)材料
選擇無性系山核桃結(jié)果樹8~10株為母本樣株,4月下旬套袋,父本分別為山核桃花粉(記作hp)和薄殼山核桃花粉(記作pp),進(jìn)行人工授粉。授粉5~7天后除去紙袋,掛牌標(biāo)記。授粉后30天開始疏果(每個(gè)結(jié)果枝只留1個(gè)果,便于氣體交換的測(cè)定),分別在山核桃果實(shí)發(fā)育關(guān)鍵時(shí)期(解紅恩等, 2008)采集相同高度的山核桃果實(shí),并進(jìn)行分析。
1.3 試驗(yàn)方法
1.3.1 果實(shí)形態(tài)和干質(zhì)量的測(cè)定 果實(shí)成熟后每處理隨機(jī)選取120個(gè)果實(shí),采用四分法分為4份,作為4個(gè)重復(fù)。果長(zhǎng)(L)、果徑(T)、果厚(W)用游標(biāo)卡尺測(cè)量,精確到0.01 mm。參照Baryeh(2001)和宋慧芝等(2011)的方法積計(jì)算果實(shí)表面積。公式如下:
(1)
(2)
式中:Dg為幾何平均徑(mm);S為表面積(cm2)。
然后將果實(shí)105 ℃殺青30 min,之后在60 ℃的烘箱烘干至恒質(zhì)量,果干物質(zhì)量用電子天平稱取,精確到0.01 g。
1.3.2 氣體交換參數(shù)的測(cè)定 選擇晴天光強(qiáng)穩(wěn)定在1 200~1 400 μmol·m-2s-1(8:00—11:00,14:00—17:00)時(shí),采用Li6400-02標(biāo)準(zhǔn)葉室(LI-COR Inc,Lincoln,USA)測(cè)定不同花粉授粉的山核桃相應(yīng)葉片的氣體交換參數(shù),以內(nèi)置紅藍(lán)光源02為光源; 采用Li6400-22簇狀葉室測(cè)定不同花粉授粉的山核桃果實(shí)的氣體交換參數(shù),以18-RGB為光源。每株樹作為1個(gè)重復(fù),4次重復(fù),每次重復(fù)3個(gè)獨(dú)立葉片、果實(shí)。
進(jìn)行氣體交換參數(shù)測(cè)定時(shí),設(shè)定葉室內(nèi)氣體流速為500 μmol·s-1,溫度為28 ℃,CO2濃度為400 μmol·mol-1,光強(qiáng)為1 300 μmol·m-2s-1。葉片光合速率為凈光合速率和呼吸速率之和; 果實(shí)光合速率為光下的光合速率和黑暗下的呼吸速率之和。山核桃果實(shí)外果皮單位面積的光合速率通過代入山核桃果實(shí)的表面積/2(與葉片光合速率的計(jì)算方法一致,只有上表面積接受光強(qiáng),所用的面積只是一面)進(jìn)行校準(zhǔn)重新計(jì)算。
1.4 數(shù)據(jù)處理方法
數(shù)據(jù)采用Excel 2007軟件進(jìn)行計(jì)算和分析,其獨(dú)立樣本t檢驗(yàn)和方差分析處理均采用SPSS18.0軟件進(jìn)行統(tǒng)計(jì)學(xué)分析處理,多重比較采用LSD法分析,利用sigmaplot12.0版專業(yè)繪圖和數(shù)據(jù)分析軟件進(jìn)行相關(guān)性分析及作圖。
2.1 2種花粉授粉山核桃果實(shí)的外觀形態(tài)、干質(zhì)量和表面積的變化
pp授粉的山核桃果實(shí)明顯大于hp花粉授粉的果實(shí),且外果皮更綠(圖1)。2種花粉授粉山核桃果實(shí)的表面積日均增量隨果實(shí)發(fā)育呈先升高后降低然后再緩慢升高的趨勢(shì)(圖2A),其干質(zhì)量日均增量隨果實(shí)發(fā)育呈先增加后下降的趨勢(shì)(圖2B)。授粉后50~73天,pp授粉的果實(shí)表面積日均增量為0.68 cm2·d-1,而hp授粉處理為0.57 cm2·d-1; 授粉后103~120天,hp授粉的果實(shí)表面積日均增量為0.26 cm2·d-1,而pp授粉處理為0.34 cm2·d-1。果實(shí)發(fā)育前期(授粉后50~73天),pp授粉的山核桃果實(shí)干質(zhì)量日均增量(0.12 gDW·d-1)高于hp授粉的果實(shí)(0.07 gDW·d-1); 果實(shí)發(fā)育后期(授粉后103~120天),pp授粉的山核桃果實(shí)日均干質(zhì)量增量(0.05 gDW·d-1)均高于hp授粉的果實(shí)(0.03 gDW·d-1)。在果實(shí)發(fā)育的各個(gè)時(shí)期,pp授粉的山核桃果實(shí)表面積和干質(zhì)量均顯著高于hp授粉的果實(shí),其中50,73,85,103和120天時(shí)pp授粉山核桃果實(shí)的表面積分別是hp授粉果實(shí)的1.35,1.26,1.23,1.18和1.2倍; pp授粉山核桃果實(shí)的干質(zhì)量分別是hp授粉果實(shí)的1.64,1.59,1.51,1.23和1.26倍。
授粉后天數(shù)Days after pollination/d圖1 果實(shí)發(fā)育過程中不同花粉授粉山核桃果實(shí)外形的變化Fig.1 Changes in shape of hickory fruits pollinated with two different pollens during the fruit growth stages
圖2 果實(shí)發(fā)育過程中2種花粉授粉山核桃果實(shí)表面積(A)和干質(zhì)量(B)的變化Fig.2 Changes in surface area (A) and mass (B) of hickory fruits pollinated with two different pollens during the fruit growth stages圖中數(shù)據(jù)為均值±標(biāo)準(zhǔn)誤差, **表示相同時(shí)期2種花粉授粉的山核桃果實(shí)之間在0.01水平達(dá)顯著差異,*表示在0.05水平達(dá)顯著差異, ns表示在0.05水平無顯著差異。 圖A和B中的小圖分別為不同發(fā)育時(shí)期內(nèi)的表面積日均增量和干質(zhì)量日均增量。 Date are presented as the means± standard error. Significant differences in hickory fruits pollinated with two different pollens :**: P<0.01; *:P<0.05; ns: P>0.05. The small figures in the Fig.2 A and B showed the increase rates of surface area and dry mass in fruits pollinated with two different pollens during the different growth stages.下同The same below.
2.2 2種花粉授粉山核桃果實(shí)的外果皮及其對(duì)應(yīng)葉片氣體交換參數(shù)的變化
隨著果實(shí)發(fā)育,2種花粉授粉山核桃外果皮單位面積的光合速率均呈先升高后降低的趨勢(shì)(圖3A)。在授粉后73天,hp和pp授粉山核桃外果皮的光合速率均達(dá)到最大值,分別7.15和9.54 μmol CO2·m-2s-1。果實(shí)發(fā)育的前中期(授粉后50~85天),pp授粉山核桃果實(shí)外果皮單位面積的光合速率均顯著高于hp授粉的果實(shí)(P<0.05),且在授粉后50,73,85天,前者分別為后者的1.31,1.32,1.33倍。
隨著果實(shí)發(fā)育,2種花粉授粉山核桃果實(shí)的對(duì)應(yīng)葉片光合速率均呈逐漸降低的趨勢(shì)。與授粉后50天相比,授粉后85天2種花粉授粉的葉片光合速率降低37%~47%。在整個(gè)果實(shí)發(fā)育過程中,2種花粉授粉山核桃果實(shí)相應(yīng)葉片的光合速率之間無顯著差異(圖3B)。
圖3 果實(shí)發(fā)育過程中2種花粉授粉山核桃果實(shí)外果皮(A)及其對(duì)應(yīng)葉片(B)單位面積上光合速率的變化Fig.3 Changes in apparent photosynthetic rate in exocarp and their corresponding leaves of the hickory fruits pollinated with two different pollens during the fruit growth stages
2.3 2種花粉授粉的山核桃果實(shí)單果日均干質(zhì)量增量與單果日均光合速度率增量之間的相關(guān)性
在果實(shí)發(fā)育過程中,分別計(jì)算一段時(shí)間內(nèi)的日平均單果干質(zhì)量和日均單果光合速率。由圖4可以看出,山核桃果實(shí)的日均單果光合速率增量與日均單果干質(zhì)量增量之間顯著相關(guān)。
圖4 山核桃果實(shí)單果日均干質(zhì)量增量與其單果光合速率日均增量的相關(guān)性Fig.4 Relationship between average daily dry mass increment and average daily apparent photosynthesis rate increment expressed on per fruit of hickory fruits日均單果干質(zhì)量增量=相鄰2個(gè)時(shí)期的干質(zhì)量增量/間隔天數(shù); 日均單果光合速率增量=日均表面積增量(相鄰2個(gè)時(shí)期的表面積增量/間隔天數(shù))×平均光合速率(相鄰2個(gè)時(shí)期的光合速率之和/2)。 Average daily dry mass increment per fruit=dry mass increment of adjacent periods / intervallic days; Daily photosynthetic rate per day=daily surface area increment/2 (surface area increment of adjacent periods / intervallic days/2)×average photosynthetic rate (the sum of adjacent two photosynthesis rate /2).
2.4 2種花粉授粉山核桃果實(shí)外果皮葉綠素含量的變化及其與外果皮光合速率相關(guān)性
由圖5可以看出,在果實(shí)發(fā)育過程中,除授粉后120天外,pp授粉的山核桃果實(shí)外果皮葉綠素含量均顯著高于hp授粉的果實(shí),均在授粉后73天達(dá)到最大值,此后開始快速下降。隨果實(shí)外果皮葉綠素含量的增加,果實(shí)外果皮平均光合速率也升高,且二者極顯著相關(guān)(圖6)。
圖5 果實(shí)發(fā)育過程中2種花粉授粉山核桃果實(shí)外果皮葉綠素含量的變化Fig.5 Changes in chlorophyll content in exocarp of hickory fruits pollinated with two different pollens during the fruit growth stages
2.5 2種花粉授粉山核桃果實(shí)外果皮葉綠素?zé)晒鈪?shù)的變化
在果實(shí)發(fā)育過程中,不同花粉授粉山核桃果實(shí)外果皮之間的Fv/Fm之間不存在顯著差異。隨著果實(shí)發(fā)育,pp授粉山核桃果實(shí)外果皮的實(shí)際光化學(xué)效率(Y)顯著高于hp授粉的果實(shí)。授粉后103~120天,hp授粉的山核桃外果皮Y下降54.7%,而pp授粉的山核桃外果皮下降30.4%。ETR代表光合作用的表觀電子傳遞速率,當(dāng)光強(qiáng)恒定時(shí),其變化決定Y的變化,不同授粉處理間的ETR變化與Y的變化趨勢(shì)相似(表1)。qP是光合機(jī)構(gòu)光系統(tǒng)Ⅱ的光化學(xué)猝滅系數(shù),表示PS Ⅱ中處于開放狀態(tài)的反應(yīng)中心所占的比例。由表1可知,隨著果實(shí)發(fā)育,pp授粉山核桃果實(shí)外果皮的qP值均顯著高于hp授粉的果實(shí)。
2.6 2種花粉授粉山核桃果實(shí)外果皮葉綠素電子傳遞特性的變化
快速光曲線是一種新的快速測(cè)定光合機(jī)構(gòu)光合作用活性的有力工具,可以反映光系統(tǒng)Ⅱ電子傳遞的飽和特性和光合活性(Ralphetal., 2005)。從圖7可以看出,光強(qiáng)從0~200 μmol·m-2s-1,不同花粉授粉山核桃果實(shí)外果皮的ETR均快速增加。授粉后50天,hp授粉山核桃果實(shí)外果皮的ETR在光強(qiáng)為770 μmol·m-2s-1達(dá)到最高值,而pp授粉山核桃果實(shí)外果皮的ETR在光強(qiáng)為1 710 μmol·m-2s-1達(dá)到最高值; 授粉后103天,hp授粉山核桃果實(shí)外果皮的ETR在光強(qiáng)710 μmol m-2s-1達(dá)到最高值,而pp授粉山核桃果實(shí)外果皮的ETR在光強(qiáng)958 μmol·m-2s-1達(dá)到最高值; 授粉后120天,hp授粉山核桃果實(shí)外果皮的ETR在光強(qiáng)為356 μmol·m-2s-1達(dá)到最高值,而pp授粉的山核桃果實(shí)外果皮的ETR在光強(qiáng)為717 μmol·m-2s-1達(dá)到最高值。
2.7 2種花粉授粉山核桃果實(shí)外果皮快速響應(yīng)曲線的變化
圖6 2種花粉授粉山核桃果實(shí)外果皮的葉綠素含量與光合速率之間的相關(guān)性Fig.6 Relationship between chlorophyll content and photosynthetic rate in exocarp of hickory fruits pollinated with two different pollens
在果實(shí)發(fā)育過程中,pp授粉山核桃果實(shí)的Y(Ⅱ)顯著高于hp授粉的山核桃果實(shí); 但2種花粉授粉處理間的Y(NPQ)無顯著差異。果實(shí)發(fā)育前期(授粉后50天)和后期(授粉后120天),pp授粉山核桃果實(shí)外果皮的Y(NO)顯著低于hp授粉的果實(shí)(圖8A1,A2,C1和C2)。授粉后103~120天,hp和pp授粉山核桃果實(shí)外果皮的Y(Ⅱ)均顯著降低。非調(diào)節(jié)性能量耗散的量子產(chǎn)量[Y(NO)]代表熒光和不依賴光的基礎(chǔ)熱耗散比例。果實(shí)發(fā)育后期(授粉后103~120天),hp授粉山核桃果實(shí)外果皮的Y(NO)顯著增加, 而pp授粉山核桃果實(shí)外果皮Y(NO)卻無顯著變化。Y(NPQ) 是調(diào)節(jié)性能量耗散的量子產(chǎn)量,其值是光保護(hù)的重要指標(biāo)。隨著果實(shí)發(fā)育,pp授粉山核桃果實(shí)外果皮的Y(NPQ)未發(fā)生顯著變化; 然而,授粉后50~103天,hp授粉山核桃果實(shí)外果皮的Y(NPQ)顯著增加(圖8)。
表1 2種花粉授粉山核桃果實(shí)外果皮的葉綠素?zé)晒鈪?shù)①
圖7 2種花粉授粉處理后山核桃果實(shí)的快速光曲線Fig.7 Rapid light curves of of hickory fruit pollinated with two different pollens during the fruit growth stagesA.授粉后50天50 d after pollination; B.授粉后103d 103 d after pollination; C.授粉后120天 120 d after pollination.
圖8 果實(shí)發(fā)育過程中不同花粉授粉山核桃果實(shí)的Y(Ⅱ)、Y(NPQ)、Y(NO)隨光合有效輻射(PAR)升高的變化Fig.8 Estimated fraction of Y(Ⅱ), Y(NPQ), and Y(NO) in exocarp of hickory fruits pollinated with two different pollens with increasing photosynthetic active radiation (PAR) during the fruit growth stagesA1: 山核桃花粉授粉后50天; B1: 山核桃花粉授粉后103天; C1: 山核桃花粉授粉后120天; A2: 薄殼山核桃花粉授粉后50天; B2: 薄殼山核桃花粉授粉后103天; C2: 薄殼山核桃花粉授粉后120天. A1: pollinated with hickory pollen at 50 d after pollination; B1: pollinated with hickory pollen at 103 d after pollination; C1: pollinated with hickory pollen at 120 d after pollination; A2: pollinated with pecan pollen at 50 d after pollination; B2: pollinated with pecan pollen at 103 d after pollination; C2: pollinated with pecan pollen at 120 d after pollination.
本研究結(jié)果顯示,pp授粉的山核桃果實(shí)顯著大于hp授粉的果實(shí),且外果皮顏色更綠(圖1),這與黎章矩等(1982)、葉茂富等(1965)、王正加等(2010)、葉浩然等(2013)的研究結(jié)果一致,存在明顯的花粉直感現(xiàn)象。AFLP和SSR分子標(biāo)記顯示子代與母本間不存在差異,表明以薄殼山核桃為父本授粉的山核桃果實(shí)變異不是由于遺傳物質(zhì)的變化引起的(王正加等, 2010)。本研究結(jié)果顯示,在果實(shí)發(fā)育過程中,pp授粉山核桃果實(shí)的外果皮表面積、干質(zhì)量均顯著高于hp授粉的果實(shí)(圖2)。許多植物的果實(shí)具有光合能力,且具有向種子運(yùn)輸距離短的特點(diǎn),對(duì)其果實(shí)、種子的生長(zhǎng)和發(fā)育具有重要的作用(Blankeetal., 1989; Birkholdetal., 1992; Paveletal., 1993; Hiekeetal., 2002; Huetal., 2012)。pp授粉的山核桃果實(shí)外果皮光合速率顯著高于hp授粉的果實(shí),而2種花粉授粉山核桃果實(shí)對(duì)應(yīng)葉片之間的光合速率是一致的(圖3),因此,筆者推測(cè)造成2種花粉授粉山核桃果實(shí)干質(zhì)量差異的原因可能是不同花粉對(duì)山核桃外果皮光合作用的差異。植物光合生產(chǎn)能力與其光合面積、光合能力、光合時(shí)間和光照強(qiáng)度均密切相關(guān)。本研究結(jié)果顯示,果實(shí)發(fā)育早期(授粉后50~73天)和后期(授粉103~120天),pp授粉山核桃果實(shí)表面積的增加速率均大于hp授粉的果實(shí)(圖2), 且在授粉后50~85天,pp授粉山核桃果實(shí)外果皮單位面積的光合速率約為hp授粉果實(shí)的1.3倍(圖3),說明pp授粉山核桃果實(shí)干質(zhì)量增量與其較大的光合面積和較高的光合能力密切有關(guān),這可以從山核桃果實(shí)日均單果干質(zhì)量與其日均單果光合速率增量的相關(guān)性分析中得到進(jìn)一步證實(shí)(圖4)。
葉綠素在光能吸收和轉(zhuǎn)化中起著重要作用,是光合作用的基礎(chǔ)。本研究結(jié)果顯示,pp授粉山核桃果實(shí)外果皮葉綠素含量顯著高于hp授粉的果實(shí)(圖5),且山核桃果實(shí)外果皮葉綠素含量與光合速率呈極顯著相關(guān)(圖6)。這表明pp授粉山核桃果實(shí)外果皮積累較多的葉綠素是其具有較高外果皮光合速率的重要原因(孫山, 2009),為提高果實(shí)自身的物質(zhì)生產(chǎn)及積累能力奠定基礎(chǔ)。
本研究表明,2種花粉授粉山核桃果實(shí)的最大光化學(xué)效率(Fv/Fm)之間無明顯差異,均在0.713~0.771之間(表1),說明2種花粉授粉山核桃外果皮對(duì)光能利用的能力是一致的。在一定強(qiáng)度光化學(xué)(1 265 μmol·m-2s-1)存在的條件下,pp授粉山核桃果實(shí)的實(shí)際光化學(xué)效率(Y)、電子傳遞速率(ETR)、光合機(jī)構(gòu)PSⅡ反應(yīng)中心的比例(qP)均顯著高于hp授粉的果實(shí),這表明具有較高光合電子傳遞能力的pp授粉的山核桃果實(shí)外果皮可能是與其具有較高的qP有關(guān)。陸地棉花(Gossypiumhirsutum)盛鈴期,‘雜交棉石雜2號(hào)’和‘新陸早43號(hào)’非葉器官(鈴殼和莖稈)的實(shí)際光化學(xué)效率顯著高于常規(guī)棉是其產(chǎn)量高的主要原因(張亞黎等, 2010)。因此,筆者推測(cè)pp授粉山核桃果實(shí)外果皮光合速率高與其具有較高的Y有關(guān)。
在果實(shí)發(fā)育過程中,不同花粉授粉山核桃果實(shí)外果皮ETR達(dá)到峰值的光強(qiáng)強(qiáng)度顯著降低,且pp授粉山核桃果實(shí)外果皮ETR達(dá)到峰值的光強(qiáng)強(qiáng)度顯著高于hp授粉的果實(shí)(圖7)。這表明,在相同的光強(qiáng)下,hp授粉的山核桃果實(shí)外果皮更易受到光抑制(Bertaminietal., 2003)。Y(NO)是光損傷的重要指標(biāo)(Ralphetal., 2005),如果Y(NO)較高,則表明此時(shí)入射光可能超過了植物能接受的程度,受到光損傷。果實(shí)發(fā)育前期(授粉后50天)和后期(授粉后120天),與hp授粉的果實(shí)相比,pp授粉果實(shí)具有較高的Y(Ⅱ)和較低的Y(NO)(圖8)。這表明在相同輻射的強(qiáng)光照射下,pp授粉的核桃果實(shí)外果皮具有較強(qiáng)的抗光抑制能力。越來越多的研究認(rèn)為,增強(qiáng)植物光合機(jī)構(gòu)的抗光抑制能力與其生物量的提高密切相關(guān)(Wangetal., 2002; Longetal., 2006)。張亞黎等(2010)研究認(rèn)為,陸地棉非葉綠色器官光合生產(chǎn)能力的提高與其較好的抗光抑制能力有關(guān)。因此,果實(shí)發(fā)育后期,pp授粉山核桃果實(shí)具有較高抗光抑制能力可能是其果實(shí)干質(zhì)量增加的重要原因。
綜上所述,薄殼山核桃授粉山核桃果實(shí)干質(zhì)量增加與其外果皮的光合作用密切相關(guān)。果實(shí)發(fā)育前期(授粉后50~73天),薄殼山核桃授粉山核桃果實(shí)干質(zhì)量快速增加是由于其果實(shí)具有較大的光合面積和較高的光合速率; 果實(shí)發(fā)育后期(授粉后103~120天),果實(shí)干質(zhì)量快速增加主要是由于其果實(shí)具有較大的光合面積。果實(shí)發(fā)育后期(授粉后120天),薄殼山核桃授粉山核桃果實(shí)具有較強(qiáng)的抗光抑制能力可能也是其干質(zhì)量增加的重要原因。
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(責(zé)任編輯 王艷娜 郭廣榮)
Variation in Photosynthetic Characteristics of Exocarp ofCaryacathayensisFruits Pollinated with Different Pollens
Xu Qinyi Wang Biao Zhao Jianwen Wu Jianfeng Cao Yirun Yang Xianyou Xia Guohua Wang Zhengjia Huang Jianqin Hu Yuanyuan
(NurturingStationfortheStateKeyLaboratoryofSubtropicalSilviculture,ZhejiangA&FUniversityLin’an311300)
【Objective】To elucidate the effect of metaxenia on photosynthesis that promotes fruit enlargement in Carya cathayensis, the shape, gas exchange, chlorophyll content and chlorophyll fluorescence characteristics of C. cathayensis fruits pollinated with two different pollens during the fruit growth stages were measured. 【Method】 Two pollination combinations (C.cathayensis×C.cathayensisorC.cathayensis×C.illinoensis) were conducted in this study. The dynamic changes in photosynthetic area, dry mass, photosynthetic rate, chlorophyll content and chlorophyll fluorescence were investigated during the fruit growth stages. 【Result】 1) The hickory fruits pollinated with pecan pollens (pp) were significant larger and greener than those pollinated with hickory pollens (hp). Compared with the hickory fruits pollinated with hp, the increasing rate of the surface area and dry mass per day per fruit was significant higher in hickory fruits pollinated with pp at the early and late fruit growth stages (from 50 to 73 d after pollination and from 103 to 120 d after pollination). The photosynthetic rate per area of exocarp in hickory fruits pollinated with pp was significantly higher than that in fruits pollinated with hp during 50 to 85 days after pollination. Moreover, a significant positive correlation was found between the dry mass increment and photosynthesis rate increment expressed on per fruit per day of hickory fruits. 2) The chlorophyll content of exocarp in fruits pollinated with pp was significantly higher than that in fruits pollinated with hp, and there was a significant positive correlation between the chlorophyll content and photosynthetic rate of exocarp in hickory fruits. 3) TheY, ETR andqPin fruits pollinated with pp were significantly higher than those in fruits pollinated with hp at PAR of 1 265 μmol·m-2s-1. The light intensity of the maximum ETR in exocarp of hickory fruits pollinated with hp was significantly lower compared with that in fruits pollinated with pp during the fruit growth stages. The light intensity of the maximum ETR in exocarp of hickory fruits pollinated with hp significantly decreased at the late fruit growth stage (from 103 to 120 d after pollination), decreased by about 50%. TheY(NO) in exocarp of hickory fruits pollinated with hp significantly increased from 103 to 120 d after pollination. Compared with pericarp of hickory fruits pollinated with hp, the exocarp of fruits pollinated with pp had higherY(II) and lowerY(NO). 【Conclusion】 At the early fruit growth stage (from 50 to 73 d after pollination), the faster increase in dry mass of the fruits pollinated with pp was due to the higher photosynthetic surface area and photosynthetic rate; at the late fruit growth stage (from 103 to 120 d after pollination), the faster increase in dry mass of the fruits pollinated with pp was due to the increased photosynthetic surface area. At the late fruit growth stage (from 103 to 120 d after pollination), the fruits pollinated with hp was more susceptible to light damage. It is suggested that the higher dry mass of fruits pollinated with pp might to related to the adaptability of high-light at the late growth stages.
hickory; exocarp; gas exchange parameters; chlorophyll fluorescence; biomass production
10.11707/j.1001-7488.20170105
2016-02-05;
2016-05-30。
浙江省自然科學(xué)基金項(xiàng)目(LY15C160003); 國(guó)家重大科學(xué)研究計(jì)劃 863計(jì)劃(2013AA102605); . 浙江省大學(xué)生科技創(chuàng)新活動(dòng)計(jì)劃資助項(xiàng)目(2015R412044); 浙江省林學(xué)重之重一級(jí)學(xué)科研究生創(chuàng)新項(xiàng)目(201502); 杭州市科技發(fā)展計(jì)劃(20130432B85)。
S718.43
A
1001-7488(2017)01-0038-09
*胡淵淵為通訊作者。