播種量和氮肥運(yùn)籌對(duì)直播雜交稻光合生產(chǎn)力及氮素利用的影響

蔣明金, 馬均, 孫永健, 嚴(yán)奉君, 徐徽, 楊志遠(yuǎn), 孫加威

(四川農(nóng)業(yè)大學(xué)水稻研究所/農(nóng)業(yè)部西南作物生理生態(tài)與耕作重點(diǎn)實(shí)驗(yàn)室,四川 溫江611130)

播種量和氮肥運(yùn)籌對(duì)直播雜交稻光合生產(chǎn)力及氮素利用的影響

蔣明金, 馬均*, 孫永健, 嚴(yán)奉君, 徐徽, 楊志遠(yuǎn), 孫加威

(四川農(nóng)業(yè)大學(xué)水稻研究所/農(nóng)業(yè)部西南作物生理生態(tài)與耕作重點(diǎn)實(shí)驗(yàn)室,四川 溫江611130)

在人工濕潤(rùn)直播條件下,以早熟雜交稻組合446A/518為試驗(yàn)材料,研究播種量和氮肥運(yùn)籌對(duì)直播稻的光合特性、物質(zhì)積累與轉(zhuǎn)運(yùn)和氮素吸收利用的影響,并探討了光合指標(biāo)與產(chǎn)量和氮素吸收利用效率的相關(guān)性。結(jié)果表明,增加播種量能提高拔節(jié)期葉面積指數(shù),同時(shí)促進(jìn)各時(shí)期氮素積累、氮素干物質(zhì)生產(chǎn)效率及稻谷生產(chǎn)效率,但抽穗后葉面積指數(shù)、SPAD值、光合速率和水稻物質(zhì)積累與轉(zhuǎn)運(yùn)能力、氮素偏生產(chǎn)力和氮素利用率則表現(xiàn)為先增加后降低。從氮肥運(yùn)籌方式來(lái)看,拔節(jié)期葉面積指數(shù)均以氮素穗肥比例40%下最大。S1、S2播種量下增加氮素穗肥比例有利于提高抽穗后葉面積指數(shù),促進(jìn)光合速率、干物質(zhì)積累量和氮素積累,提高物質(zhì)積累與轉(zhuǎn)運(yùn)能力和氮素吸收利用效率。而播種量增大到30.0 kg/hm2時(shí),氮肥適當(dāng)前移更有利于水稻養(yǎng)分的吸收,并促進(jìn)水稻物質(zhì)積累與轉(zhuǎn)運(yùn)能力和提高氮肥利用率。相關(guān)分析表明,抽穗期光合作用速率和葉面積指數(shù)與產(chǎn)量和氮素吸收利用效率均表現(xiàn)為顯著正相關(guān)。總之,播種量22.5 kg/hm2,以氮素基肥、蘗肥和穗肥分別占40%、10%和50%的運(yùn)籌方式能獲得最佳產(chǎn)量,且具備較高的光合作用效率、干物質(zhì)生產(chǎn)效率及氮素利用效率,為本試驗(yàn)最佳處理。

播種量; 氮肥運(yùn)籌; 光合生產(chǎn)力; 氮素吸收; 氮素利用率

四川盆地因“低光值、小溫差、高濕度”的氣候特點(diǎn),水稻生產(chǎn)主要以育秧移栽為主。近年來(lái),由于農(nóng)村勞動(dòng)力的減少和家庭農(nóng)場(chǎng)、種糧大戶(hù)、土地流轉(zhuǎn)、農(nóng)業(yè)合作社等新型農(nóng)村經(jīng)營(yíng)主體的迅速發(fā)展,直播水稻的發(fā)展越來(lái)越受到關(guān)注。且隨著直播技術(shù)的進(jìn)一步成熟,水稻直播技術(shù)已在全國(guó)12個(gè)省市推廣應(yīng)用,表現(xiàn)出了顯著的增產(chǎn)增效作用[1]?；糁醒蟮萚2-4]、倪竹如等[5]通過(guò)播期、種植方式和氮肥施用技術(shù)初步探明了直播水稻光合物質(zhì)生產(chǎn)特性、氮素吸收利用特性。就四川特殊的氣候、地形條件和雜交水稻而言,直播水稻研究相對(duì)甚少,前人在機(jī)械旱直播方式[6]、精量穴直播[7]和機(jī)械化播插[8]等方面對(duì)直播水稻生長(zhǎng)發(fā)育有了初步研究,但在研究過(guò)程中氮肥施用方式大多沿用移栽稻高產(chǎn)栽培管理方式進(jìn)行,而直播水稻無(wú)育秧移栽環(huán)節(jié),移栽稻氮肥管理方式是否適用于直播水稻仍不明確,這不僅在一定程度上存在潛在的肥料浪費(fèi),也可能使得水稻減產(chǎn)。此外,前人對(duì)直播水稻播種量的確定也不一致,從15.0 kg/hm2到37.5 kg/hm2不等[9-11],而播種量的多少會(huì)直接影響到水稻群體質(zhì)量,進(jìn)而影響產(chǎn)量。且前人的研究多以常規(guī)稻為主,對(duì)雜交水稻直播研究較少。因此,有必要進(jìn)一步研究播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻物質(zhì)生產(chǎn)特性及氮素吸收利用規(guī)律。

本研究以早熟雜交稻組合446A/518為試驗(yàn)材料,在人工濕潤(rùn)直播(撒播)基礎(chǔ)上設(shè)置3種播種量和3種氮肥運(yùn)籌方式,研究直播雜交稻光合特性、物質(zhì)生產(chǎn)能力以及氮素吸收利用規(guī)律,旨在進(jìn)一步了解不同播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻物質(zhì)轉(zhuǎn)運(yùn)及氮素吸收利用的影響,明確四川盆地直播雜交稻技術(shù)適宜的播種量和氮肥運(yùn)籌方式,從而為雜交水稻機(jī)械化直播的進(jìn)一步發(fā)展及推廣應(yīng)用提供理論和實(shí)踐依據(jù)。

1 材料與方法

1.1 供試材料

試驗(yàn)材料為早熟雜交稻組合446A/518,全生育期約118 d,由四川農(nóng)業(yè)大學(xué)水稻研究所提供。

1.2 試驗(yàn)設(shè)計(jì)

試驗(yàn)于2013年在四川成都溫江區(qū)四川農(nóng)業(yè)大學(xué)水稻研究所試驗(yàn)農(nóng)場(chǎng)進(jìn)行,試驗(yàn)地前茬大蒜,耕層土壤質(zhì)地為沙壤土,含全氮1.12 g/kg,速效氮157.54 mg/kg,速效鉀80.65 mg/kg,速效磷69.81 mg/kg。

試驗(yàn)采用2因素裂區(qū)設(shè)計(jì),播種量為主區(qū),氮肥運(yùn)籌為副區(qū)。設(shè)3個(gè)播種量處理,即15.0 kg/hm2、22.5 kg/hm2和30.0 kg/hm2,分別記為S1、S2和S3。在總氮(N)用量為150 kg/hm2的前提下,設(shè)置3個(gè)氮肥運(yùn)籌方式,即基肥、蘗肥和穗肥的比例分別為N1:50%、20%和30%;N2:30%、30%和40%;N3:40%、10%和50%,并在播種量15.0、22.5和30.0 kg/hm2下設(shè)置不施氮肥處理(分別為CK1、CK2和CK3)為對(duì)照,3次重復(fù)。試驗(yàn)所用種子經(jīng)篩選、催芽至露白后于2013年5月8日采用人工濕潤(rùn)直播(撒播)進(jìn)行播種。磷肥(P2O5含量為75 kg/hm2)于播種前全部以基肥形式施入,鉀肥(K2O含量為150 kg/hm2)以基肥和穗肥按照70%和30%分次施入。小區(qū)面積15 m2,各小區(qū)之間筑埂并地膜覆蓋,其余田間管理按照當(dāng)?shù)爻Ｒ?guī)管理方式。

1.3 分析測(cè)定項(xiàng)目及方法

1.3.1 葉面積測(cè)定 分別于拔節(jié)期和抽穗期各小區(qū)選擇生長(zhǎng)基本一致植株5株,用葉面積儀CI-203測(cè)定拔節(jié)期葉面積、抽穗期上三葉葉面積和其余葉葉面積,并計(jì)算葉面積指數(shù)。

1.3.2 光合特性和SPAD值 于抽穗期和齊穗后15 d，晴天上午9:00—11:00左右采用便攜式光合測(cè)定系統(tǒng)LI-6400(美國(guó)LI-COR公司生產(chǎn))測(cè)定劍葉光合作用速率、氣孔導(dǎo)度以及蒸騰速率,用SPAD儀測(cè)定劍葉中部的SPAD值。每個(gè)處理測(cè)定生長(zhǎng)基本一致葉片5片,重復(fù)測(cè)定3次。

1.3.3 物質(zhì)轉(zhuǎn)運(yùn)及氮素含量測(cè)定 于拔節(jié)期、抽穗期和成熟期,根據(jù)各小區(qū)田間長(zhǎng)勢(shì)取生長(zhǎng)基本一致的植株5株。分莖(鞘)、葉和穗3部分分別放于恒溫干燥箱內(nèi),105 ℃下殺青45 min,而后經(jīng)80 ℃下烘干至恒重,分別稱(chēng)取相應(yīng)干質(zhì)量。莖(鞘)、葉和穗分別粉碎(80目篩)過(guò)篩,采用濃H2SO4-H2O消煮,用凱氏定氮儀(FOSS-8400)測(cè)定各器官的全氮含量。

1.3.4 產(chǎn)量測(cè)定 成熟期,分小區(qū)收割,按實(shí)際面積計(jì)產(chǎn)。

1.4 參數(shù)計(jì)算

物質(zhì)轉(zhuǎn)運(yùn)及氮素吸收、利用相關(guān)計(jì)算方法[12-14]如下:

干物質(zhì)積累量/(kg/hm2)=該時(shí)期單位面積莖鞘、葉及穗干質(zhì)量之和;

莖鞘物質(zhì)輸出率/%=(齊穗期莖鞘干質(zhì)量-成熟期莖鞘干質(zhì)量)/齊穗期莖鞘干質(zhì)量×100;

莖鞘物質(zhì)轉(zhuǎn)換率/%=(齊穗期莖鞘干質(zhì)量-成熟期莖鞘干質(zhì)量)/籽粒干質(zhì)量×100;

莖鞘(葉)氮轉(zhuǎn)運(yùn)量/(kg/hm2)=齊穗期莖鞘(葉)氮素積累量-成熟期莖鞘(葉)氮素積累量;

莖鞘(葉)氮素轉(zhuǎn)運(yùn)率/%=莖鞘(葉)氮素轉(zhuǎn)運(yùn)量/齊穗期莖鞘(葉)氮素積累量×100;

莖鞘(葉)氮素貢獻(xiàn)率/%=莖鞘(葉)氮素轉(zhuǎn)運(yùn)量/成熟期籽粒含氮量×100;

氮素干物質(zhì)生產(chǎn)效率/%=單位時(shí)間植株干物質(zhì)積累量/單位時(shí)間植株氮積累總量;

氮素稻谷生產(chǎn)效率/%=籽粒產(chǎn)量/氮積累量;

氮素收獲指數(shù)/%=籽粒含氮量/植株總吸氮量×100;

氮肥偏生產(chǎn)力/(kg/kg)=籽粒產(chǎn)量/施氮量;

氮素農(nóng)學(xué)效率/%=(施氮區(qū)產(chǎn)量-未施氮區(qū)產(chǎn)量)/施氮量×100;

氮表觀利用率/%=(施氮區(qū)植株吸氮量-未施氮區(qū)植株吸氮量)/施氮量×100。

在氮素農(nóng)學(xué)效率和氮表觀利用率的計(jì)算中,不同播種量處理與相應(yīng)的未施氮處理對(duì)應(yīng)計(jì)算(即S1對(duì)應(yīng)CK1,S2對(duì)應(yīng)CK2,S3對(duì)應(yīng)CK3)。

1.5 數(shù)據(jù)分析

用Microsoft Excel 2013、DPS 7.05和Origin 9.2進(jìn)行統(tǒng)計(jì)分析和作圖。用最小顯著差異法(least significant difference,LSD)檢驗(yàn)處理間差異顯著性。

2 結(jié)果與分析

2.1 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻光合特性的影響

由表1表明,播種量和氮肥運(yùn)籌處理對(duì)直播稻葉面積指數(shù)和粒葉比的影響大多達(dá)到顯著水平。從播種量看,拔節(jié)期葉面積指數(shù)隨著播種量的增加而增加,抽穗期葉面積指數(shù)、上三葉葉面積指數(shù)和上三葉葉面積率隨播種量的增加表現(xiàn)為先增加后降低,粒葉比在播種量為15.0 kg/hm2(S1)和22.5 kg/hm2(S2)下相當(dāng)。就氮肥運(yùn)籌方式處理來(lái)看,僅對(duì)抽穗期上三葉葉面積比率的影響未達(dá)到顯著水平。在不同播種量下拔節(jié)期葉面積指數(shù)均隨著氮素穗肥比例的增加表現(xiàn)為先增加后降低,抽穗期葉面積指數(shù)和上三葉葉面積指數(shù)在S1、S3條件下表現(xiàn)為穗肥占總氮50%(N3)處理相對(duì)較高,而在S2條件下則以N1處理相對(duì)較高,抽穗期上三葉葉面積比率和粒葉比均在N3處理下相對(duì)較高。

表1 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻葉面積指數(shù)及粒葉比的影響

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

LAI: Leaf area index; S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

從表2可以看出,除播種量處理對(duì)齊穗后15 d的光合作用速率、氣孔導(dǎo)度和蒸騰速率以及播種量和氮肥運(yùn)籌方式之間的互作對(duì)氣孔導(dǎo)度的影響不顯著外,播種量、氮肥運(yùn)籌方式及其互作對(duì)抽穗期和齊穗后15 d的SPAD值、光合作用速率、氣孔導(dǎo)度和蒸騰速率的影響均達(dá)到顯著水平。SPAD值、光合作用速率、氣孔導(dǎo)度和蒸騰速率在抽穗期隨著播種量的增加均表現(xiàn)為先增加后降低,而在齊穗后15 d則大體表現(xiàn)為先降低而后增加。從氮肥運(yùn)籌方式來(lái)看,播種量在S1、S2條件下,抽穗期SPAD值均在N2下最大,N1下最小,光合作用速率、氣孔導(dǎo)度和蒸騰速率均以N3處理下相對(duì)較高。在S3條件下,抽穗期和齊穗后15 d其SPAD值均隨著氮素穗肥比例的增加而變大,光合作用速率在抽穗期時(shí)隨著氮素穗肥比例表現(xiàn)為先增加后降低,而在齊穗后15 d表現(xiàn)為持續(xù)增加,氣孔導(dǎo)度和蒸騰速率則在N2、N3處理下相對(duì)較大。

2.2 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻物質(zhì)積累與轉(zhuǎn)運(yùn)的影響

從圖1可以看出,播種量和氮肥運(yùn)籌方式以及它們之間的互作對(duì)水稻拔節(jié)期、抽穗期和成熟期干物質(zhì)積累量的影響均較大。從播種量來(lái)看,3個(gè)時(shí)期干物質(zhì)積累量均在播種量為22.5 kg/hm2時(shí)最大,拔節(jié)期總干物質(zhì)積累量在播種量為30.0 kg/hm2時(shí)最低,而抽穗期和成熟期時(shí)干物質(zhì)積累量則在播種量為15.0 kg/hm2時(shí)較低。在不同播種量下,氮肥運(yùn)籌方式對(duì)水稻干物質(zhì)積累量的影響基本一致。S1條件下,隨著氮素穗肥的增加,干物質(zhì)積累量均有不同程度的增加,3個(gè)時(shí)期干物質(zhì)積累量均表現(xiàn)為N3>N2>N1,差異顯著。在S2條件下,隨著氮素穗肥的增加,拔節(jié)期和抽穗期干物質(zhì)積累量均表現(xiàn)為不同程度的增加,而成熟期干物質(zhì)積累量則分別在N3和N2處理下達(dá)到最高和最低,且差異達(dá)到顯著水平。在S3條件下,不同氮肥運(yùn)籌方式對(duì)干物質(zhì)積累量均表現(xiàn)為N2處理下最高,而在N1處理下較低。

表2 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻SPAD值和光合作用速率的影響

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

柱狀圖上的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。 Different lowercase letters above the columns indicate statistically significant differences of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability level.圖1 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻主要生育時(shí)期干物質(zhì)積累量的影響Fig.1 Effect of nitrogen fertilizer management on dry matter accumulation at main growth stages of hybrid rice under different seeding rates

從表3可見(jiàn),抽穗期莖鞘干物質(zhì)量、成熟期莖鞘干物質(zhì)量、抽穗后干物質(zhì)積累量、莖鞘物質(zhì)的輸出率和轉(zhuǎn)換率受播種量、氮肥運(yùn)籌方式和它們之間互作的影響大多達(dá)到顯著或極顯著水平。其中,抽穗期莖鞘干物質(zhì)量、成熟期莖鞘干物質(zhì)量和抽穗后干物質(zhì)積累量均在播種量為22.5 kg/hm2(S2)時(shí)最高,且能獲得較高的莖鞘物質(zhì)的輸出率和轉(zhuǎn)換率以及產(chǎn)量。而在播種量為15.0 kg/hm2(S1)時(shí),盡管其抽穗后干物質(zhì)積累量比播種量為30.0 kg/hm2(S3)下稍高,但由于其莖鞘物質(zhì)輸出率和莖鞘物質(zhì)轉(zhuǎn)換率均較低,未能獲得高產(chǎn)。

從氮肥運(yùn)籌方式來(lái)看,在不同播種量下氮肥運(yùn)籌方式對(duì)水稻物質(zhì)積累和轉(zhuǎn)運(yùn)均有較大影響。S1條件下,氮素穗肥比例增加能提高抽穗期莖鞘干物質(zhì)量以及抽穗后干物質(zhì)積累量,而成熟期莖鞘的干物質(zhì)量則為先增加后降低,莖鞘物質(zhì)的輸出率和轉(zhuǎn)換率則與成熟期莖鞘干物質(zhì)量的規(guī)律則相反。S2條件下,N3處理能提高抽穗期、成熟期莖鞘干物質(zhì)量,而抽穗后干物質(zhì)積累量則隨著氮素穗肥的增加先降低后增加。莖鞘物質(zhì)輸出率和莖鞘物質(zhì)轉(zhuǎn)換率均表現(xiàn)為N2下最大,N1下最小。S3條件下,隨著氮素穗肥比例的增加,抽穗期和成熟期莖鞘干物質(zhì)量以及抽穗后的干物質(zhì)積累量均表現(xiàn)先增加后降低,而莖鞘的物質(zhì)輸出與轉(zhuǎn)運(yùn)能力規(guī)律與之相反。

2.3 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻主要生育期氮素積累的影響

除播種量對(duì)抽穗期和成熟期葉氮素積累量以及抽穗期穗部氮素積累量的差異不明顯外,播種量、氮肥運(yùn)籌方式以及它們之間的互作對(duì)不同生育時(shí)期各器官氮素積累量的影響均達(dá)到顯著水平(表4)。就播種量而言,各主要生育時(shí)期下莖鞘氮素積累量、拔節(jié)期的葉氮素積累量和成熟期穗氮素積累量均表現(xiàn)為S2處理下最大,S3最小,差異明顯。抽穗期和成熟期的葉片氮素積累量和抽穗期穗部氮素積累量在3種播種量下差異不大,但均在S2處理下相對(duì)較高。

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

從氮肥運(yùn)籌處理來(lái)看,不同播種量時(shí)氮肥運(yùn)籌對(duì)水稻主要生育期各器官氮素積累量影響差異較大。在S1、S2條件下,氮素穗肥比例占總氮50%(N3處理)時(shí)能促進(jìn)拔節(jié)期、抽穗期和成熟期莖鞘與葉片以及穗部氮素積累,由此可以看出在此播種量下適當(dāng)?shù)仕敕实谋壤軌虼龠M(jìn)植株氮素的積累。而當(dāng)播種量增加到30.0 kg/hm2(S3)時(shí),直播水稻主要生育時(shí)期各器官氮素積累規(guī)律均隨著氮素穗肥比例的增加表現(xiàn)為先增加后降低,且N1和N3處理下主要生育時(shí)期各器官氮素積累量的差異不明顯。

2.4 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻氮素轉(zhuǎn)運(yùn)能力的影響

從表5可以看出,播種量、氮肥運(yùn)籌方式以及它們之間的互作對(duì)莖鞘和葉片氮素轉(zhuǎn)運(yùn)量、氮素轉(zhuǎn)運(yùn)率以及氮素貢獻(xiàn)率的影響大多達(dá)到顯著或極顯著的水平。就播種量而言,莖鞘氮素轉(zhuǎn)運(yùn)量和氮素轉(zhuǎn)運(yùn)貢獻(xiàn)率均表現(xiàn)為S1>S2>S3,而葉片氮素貢獻(xiàn)率表現(xiàn)與之相反;葉片氮素轉(zhuǎn)運(yùn)量和氮素轉(zhuǎn)運(yùn)率均表現(xiàn)為S2>S3>S1,莖鞘氮素轉(zhuǎn)運(yùn)率分別在S1下最大,S2下最小。

從氮肥運(yùn)籌方式來(lái)看,在S1、S3條件下,氮肥運(yùn)籌方式對(duì)直播水稻氮素轉(zhuǎn)運(yùn)的影響規(guī)律大體一致。其中,隨著氮素穗肥比例的增加,莖鞘氮素轉(zhuǎn)運(yùn)量均有所降低,莖鞘氮素轉(zhuǎn)運(yùn)率和貢獻(xiàn)率則表現(xiàn)為先降低后增加,而葉片氮素轉(zhuǎn)運(yùn)量、轉(zhuǎn)運(yùn)率和貢獻(xiàn)率均表現(xiàn)為先增加后降低,但增加或降低的程度均有所不同,差異顯著。S2條件下與S1、S3條件下氮肥運(yùn)籌對(duì)水稻氮素轉(zhuǎn)運(yùn)的影響差異較大。主要表現(xiàn)在增加氮素穗肥比例,莖鞘氮素轉(zhuǎn)運(yùn)量、轉(zhuǎn)運(yùn)率和貢獻(xiàn)率均表現(xiàn)為先增加后降低,這與S1、S3條件下基本呈相反趨勢(shì),而葉片氮素轉(zhuǎn)運(yùn)量隨著氮素穗肥比例的增加表現(xiàn)為先降低而后增加,葉片氮素轉(zhuǎn)運(yùn)率和貢獻(xiàn)率則持續(xù)下降,且N1處理顯著高于N2、N3處理。

2.5 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻氮素吸收利用的影響

由表6可知,播種量、氮肥運(yùn)籌方式以及它們之間的互作對(duì)氮素吸收與利用的影響大多均達(dá)到顯著或極顯著水平。在不同播種量下氮素干物質(zhì)生產(chǎn)效率和氮素稻谷生產(chǎn)效率均表現(xiàn)為S3>S2>S1,在一定范圍內(nèi)增加播種量有利于氮肥偏生產(chǎn)力、氮素農(nóng)學(xué)效率以及氮表觀利用率的增加,但繼續(xù)增加則反而降低。氮素的收獲指數(shù)在不同播種量下差異不明顯。

表5 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻氮素轉(zhuǎn)運(yùn)的影響

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

表6 在不同播種量下氮肥運(yùn)籌方式對(duì)直播雜交稻氮素吸收利用的影響

S1:播種量為15.0 kg/hm2;S2:播種量為22.5 kg/hm2;S3:播種量為30.0 kg/hm2;N1:基肥、蘗肥和穗肥分別占50%、20%和30%;N2:基肥、蘗肥和穗肥分別占30%、30%和40%;N3:基肥、蘗肥和穗肥分別占40%、10%和50%。同列數(shù)據(jù)后的不同小寫(xiě)字母表示在同一播種量下3個(gè)氮肥運(yùn)籌之間在P<0.05水平差異有統(tǒng)計(jì)學(xué)意義。

S1: Seeding rate of 15.0 kg/hm2; S2: Seeding rate of 22.5 kg/hm2; S3: Seeding rate of 30.0 kg/hm2; N1: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 50%, 20% and 30%, respectively; N2: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 30%, 30% and 40%, respectively; N3: Ratio of nitrogen application at transplanting stage, tillering stage and booting stage is 40%, 10% and 50%, respectively. Values within a column followed by different lowercase letters indicate the significant difference of the same seeding rate different among three nitrogen fertilizer managements at the 0.05 probability levels。

從氮肥運(yùn)籌方式來(lái)看,在S1、S2條件下,氮素稻谷生產(chǎn)效率和氮素收獲指數(shù)均在N1下相對(duì)較大,氮素利用效率均表現(xiàn)為N3>N2>N1,且差異達(dá)到顯著水平,而氮素干物質(zhì)生產(chǎn)效率則表現(xiàn)各異。在S3條件下氮肥運(yùn)籌方式對(duì)氮素吸收與利用的影響與在S1、S2下有所不同,其中,增加氮素穗肥比例有利于提高氮素干物質(zhì)生產(chǎn)效率,而氮肥偏生產(chǎn)力、氮素農(nóng)學(xué)效率和氮表觀利用率均隨著氮素穗肥比例的增加表現(xiàn)為先增加后降低,且N2與N1、N3處理差異達(dá)到顯著水平,而氮素稻谷生產(chǎn)效率和氮素收獲指數(shù)則在不同氮肥運(yùn)籌方式下差異不顯著。

3 討論

3.1 播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻光合生理特性的影響

前人研究表明,提高結(jié)實(shí)期群體光合積累量的形態(tài)生理基礎(chǔ)指標(biāo)主要是適宜LAI、葉片著生狀態(tài)和高效葉面積[15]。同時(shí),較大的葉面積(特別是較高的上三葉葉面積)和葉片中葉綠素含量能夠提高群體光合效率和劍葉的凈光合速率,從而延緩植株的衰老,為抽穗后干物質(zhì)積累和籽粒灌漿奠定基礎(chǔ)[16]。從本試驗(yàn)來(lái)看,增加直播稻播種量在一定程度能提高拔節(jié)期葉面積指數(shù),抽穗后葉面積指數(shù)、上三葉葉面積指數(shù)、SPAD值、光合作用速率、氣孔導(dǎo)度和蒸騰速率則表現(xiàn)為先增加后降低,對(duì)齊穗后15 d光合效率的影響不大。由此可以看出,增加播種量雖然能夠在前期增大水稻葉面積指數(shù),但在后期由于群體過(guò)大會(huì)使下部葉片過(guò)早枯黃死亡、降低葉面積指數(shù),同時(shí)光合效率和SPAD值均會(huì)有所下降。而從氮肥運(yùn)籌方式來(lái)看,3種播種量下,氮肥適當(dāng)后移(N2處理)能夠提高水稻抽穗前期葉面積指數(shù),將氮肥后移(N3處理)有利于提高抽穗后水稻葉面積指數(shù)、光合作用效率、氣孔導(dǎo)度和蒸騰速率。結(jié)合播種量和氮肥運(yùn)籌組合而言,播種量控制在22.5 kg/hm2左右,氮素穗肥比例為50%下雖然其拔節(jié)期葉面積指數(shù)略小于S2與N2組合,但其抽穗后上三葉葉面積指數(shù)較大,同時(shí)有較高的光合效率和SPAD值,為后期干物質(zhì)積累和籽粒灌漿均打下了較好的基礎(chǔ)。

3.2 播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻物質(zhì)積累與轉(zhuǎn)運(yùn)的影響

群體干物質(zhì)量和抽穗后干物質(zhì)積累量與水稻產(chǎn)量均有較大關(guān)系。張中華[17]研究表明,直播稻播種量與拔節(jié)期干物質(zhì)量呈顯著線(xiàn)性正相關(guān),與抽穗后干物質(zhì)積累量呈顯著拋物線(xiàn)關(guān)系,同時(shí)認(rèn)為在播種量為15 kg/hm2和22.5 kg/hm2時(shí)抽穗后干物質(zhì)積累量較高,并能獲得較理想產(chǎn)量。吳桂成等[18]認(rèn)為,隨著播種量的增加,拔節(jié)期干物質(zhì)量表現(xiàn)為持續(xù)增加,抽穗期干物質(zhì)量則表現(xiàn)先增加之后變化不明顯,而抽穗后干物質(zhì)量在播種量為22.5 kg/hm2和33.0 kg/hm2時(shí)顯著高于15.0 kg/hm2,具有較大增產(chǎn)潛力。本研究表明,播種量與氮肥運(yùn)籌方式對(duì)水稻干物質(zhì)的積累與轉(zhuǎn)運(yùn)能力的影響均較大。水稻物質(zhì)積累與轉(zhuǎn)運(yùn)能力均隨著播種量的增加表現(xiàn)為先增加后降低,且在播種量30.0 kg/hm2(S3)條件下,除抽穗后干物質(zhì)積累量相對(duì)15.0 kg/hm2(S1)較低外,水稻物質(zhì)積累與轉(zhuǎn)運(yùn)能力均比S1高。由此可以看出,直播稻播種量不能過(guò)低或過(guò)高,合理的播種量有利于群體密度和個(gè)體的協(xié)調(diào)發(fā)展,獲得較高的葉面積指數(shù),提高光合作用效率,且具備較高的物質(zhì)積累與轉(zhuǎn)運(yùn)能力,進(jìn)而提高水稻產(chǎn)量。

在不同播種量下，氮肥運(yùn)籌方式對(duì)水稻干物質(zhì)生產(chǎn)效率的影響較大。播種量小于22.5 kg/hm2(S1和S2)時(shí),增加氮素穗肥比例能促進(jìn)拔節(jié)期、抽穗期和成熟期干物質(zhì)積累以及抽穗期和成熟期莖鞘干物質(zhì)量,當(dāng)播種量繼續(xù)增加到30.0 kg/hm2(S3)時(shí),水稻主要生育時(shí)期干物質(zhì)積累量、抽穗期和成熟期莖鞘干物質(zhì)量均隨穗肥比例的增加表現(xiàn)為先增加后降低。而抽穗后干物質(zhì)積累量、莖鞘物質(zhì)輸出率和轉(zhuǎn)換率在不同播種量下隨著氮素穗肥比例的增加表現(xiàn)卻不一致。這可能是因?yàn)?播種量較小時(shí),在N1、N2氮肥運(yùn)籌方式下前期氮肥用量基本能夠滿(mǎn)足群體和個(gè)體生長(zhǎng)的需求,提高穗肥時(shí)期氮肥用量能促進(jìn)后期群體和個(gè)體的生長(zhǎng),提高物質(zhì)積累與轉(zhuǎn)運(yùn)能力并獲得較高產(chǎn)量。而播種量過(guò)大時(shí),群體數(shù)量大,如果前期氮肥施用不足會(huì)使得群體中個(gè)體難以較好的生長(zhǎng),進(jìn)而影響前期群體結(jié)構(gòu),將氮肥用量適當(dāng)傾向于基、蘗肥,使得個(gè)體可吸收養(yǎng)分充足,保證了抽穗前后莖鞘干物質(zhì)量的積累達(dá)到一定程度,物質(zhì)轉(zhuǎn)運(yùn)能力適當(dāng),可獲得相對(duì)理想的產(chǎn)量。因此,氮肥運(yùn)籌對(duì)水稻干物質(zhì)積累量與轉(zhuǎn)運(yùn)受播種量的影響較大,在一定播種量范圍內(nèi),提高氮肥穗肥比例有助于提高干物質(zhì)積累量并獲得較高的物質(zhì)轉(zhuǎn)運(yùn)能力,而播種量過(guò)大時(shí),則需要適當(dāng)將氮肥前移以滿(mǎn)足水稻前期群體與個(gè)體的協(xié)調(diào)生長(zhǎng)。

3.3 播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻氮肥利用的影響

徐春梅等[19]認(rèn)為施氮量以及群體密度的增加可以提高葉片氮素轉(zhuǎn)運(yùn)量,且氮素偏生產(chǎn)力、氮素農(nóng)學(xué)利用率以及氮素收獲指數(shù)與施肥量之間的關(guān)系表現(xiàn)為顯著負(fù)相關(guān),同時(shí)密度過(guò)大會(huì)使得氮素農(nóng)學(xué)利用率以及氮素收獲較低。本研究表明,增加播種量能促進(jìn)各主要生育時(shí)期水稻氮素的積累、干物質(zhì)生產(chǎn)以及稻谷生產(chǎn)效率,但會(huì)降低莖鞘氮素轉(zhuǎn)運(yùn)量,而葉片氮素轉(zhuǎn)運(yùn)量、氮素偏生產(chǎn)力以及氮素利用率則表現(xiàn)為先升高后降低,播種量對(duì)氮素收獲指數(shù)的影響不明顯。氮素積累量和氮素轉(zhuǎn)運(yùn)能力與產(chǎn)量均呈顯著正相關(guān)。從本試驗(yàn)可知,在播種量為22.5 kg/hm2時(shí)能獲得較高的氮素積累量和氮素利用效率,繼續(xù)提高播種量雖然能夠有利于干物質(zhì)生產(chǎn)效率或稻谷生產(chǎn)能力,但也會(huì)降低氮肥的利用效率,且造成產(chǎn)量降低。

氮素利用效率受多種因素影響。林洪鑫等[20]研究表明,氮肥后移能夠提高莖鞘和葉片的氮素轉(zhuǎn)運(yùn)率,中氮水平氮肥后移可以提高水稻產(chǎn)量、生物產(chǎn)量、氮素積累量以及氮肥利用效率。本研究表明,在S1、S2條件下,增加氮素穗肥比例可以提高氮素積累量、氮素農(nóng)學(xué)效率和氮表觀利用率,雖然在一定程度上降低了氮素稻谷生產(chǎn)效率和氮素收獲指數(shù),但能夠獲得較理想的產(chǎn)量;而當(dāng)播種量在30.0 kg/hm2時(shí),增施氮素穗肥能促進(jìn)氮素干物質(zhì)生產(chǎn)效率,但氮素積累量、氮素偏生產(chǎn)能力以及氮素的利用率表現(xiàn)為先增加后降低。由此可以看出,在播種量低于22.5 kg/hm2時(shí),通過(guò)合理的氮素基、蘗肥以滿(mǎn)足水稻植株前期氮肥需求的同時(shí),適當(dāng)提高氮素穗肥的比例能夠提高水稻氮素的積累并促進(jìn)氮素的吸收與利用。而播種量過(guò)大則需要適當(dāng)將氮肥前移以滿(mǎn)足前期水稻對(duì)氮素需求,提高氮肥利用。

4 結(jié)論

播種量和氮肥運(yùn)籌方式對(duì)直播雜交稻的光合特性、物質(zhì)積累與轉(zhuǎn)運(yùn)和氮素吸收與利用的影響大多都達(dá)到顯著和極顯著的水平,且抽穗期葉面積指數(shù)和光合作用效率與水稻產(chǎn)量和氮素利用效率存在一定的正相關(guān)關(guān)系。就本試驗(yàn)來(lái)看,當(dāng)播種量低于22.5 kg/hm2時(shí),氮肥適當(dāng)后移能夠促進(jìn)后期群體生長(zhǎng),提高水稻產(chǎn)量、干物質(zhì)生產(chǎn)效率以及氮素吸收和利用效率。而當(dāng)播種量增加到30.0 kg/hm2時(shí),氮肥適當(dāng)前移可以提高水稻產(chǎn)量和氮素的吸收與利用。結(jié)合產(chǎn)量、干物質(zhì)生產(chǎn)效率和氮素吸收利用來(lái)看,在播種量為22.5 kg/hm2下采用基肥、蘗肥和穗肥分別占40%、10%和50%的氮肥運(yùn)籌方式，能有較好的光合特性、較強(qiáng)的物質(zhì)積累與轉(zhuǎn)運(yùn)能力以及較高的氮素吸收利用效率,為本試驗(yàn)最佳組合。

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Effects of seeding rates and nitrogen fertilizer managements on photosynthetic productivity and nitrogen utilization in direct-seeded rice.

Journal of Zhejiang University (Agric. & Life Sci.), 2015,41(5):516-526

Jiang Mingjin, Ma Jun*, Sun Yongjian, Yan Fengjun, Xu Hui, Yang Zhiyuan, Sun Jiawei

(KeyLaboratoryofCropPhysiology,Ecology,andCultivationinSouthwestChina,MinistryofAgriculture/RiceResearchInstitute,SichuanAgriculturalUniversity,Wenjiang611130,Sichuan,China)

Due to the climatic feature of low light, small temperature difference and high humidity, transplanting rice was the major pattern in rice production in Sichuan Basin. As the rural labor force was decreased and the new types of rural management body were developing rapidly, the development of direct-seeded rice has becoming increasingly concerned. With the further development of direct seeding technology,direct seeding technique of rice has been successfully applied in 12 provinces and cities in China, which showed a significant role in improving the production and efficiency. In terms of the particular climate, topographic condition, and the hybrid rice in Sichuan Province, there were few studies on direct-seeded rice. Many researches had been done on the growth and development in direct-seeded rice under mechanical dry direct seeding and precision hill-direct-seeding, but the nitrogen management in those studies was according to the high-yield cultivation management of transplanting rice, and whether the nitrogen fertilizer management of transplanting rice was appropriate for direct-seeded rice was undefined. Seeding rate could immediate affect the population quality of rice plants and grain yield. The former researches often used the conventional rice as material but not the hybrid rice, so, further studies on the effects of seeding rate and nitrogen management on the dry matter production characteristic, nitrogen absorption and utilization law in direct-seeded hybrid rice were necessary.

Hybrid rice 446A/518 was used to investigate the effects of seeding rate and nitrogen fertilizer management on the photosynthetic productivity, dry matter accumulation and translocation, nitrogen absorption and utilization under manual wet direct-seeding, and the correlation among the three which are photosynthesis index, grain yield and nitrogen utilization efficiency of rice plants were also taken to analyze.

The results indicated that increasing the seeding rate would enhance the leaf area index during jointing stage and promote the nitrogen accumulation, nitrogen use efficiency (NUE) for biomass production and NUE for grain production. However, the leaf area index (LAI), SPAD value, photosynthetic rate, dry matter accumulation and translocation, partial factor productivity of applied nitrogen and NUE firstly increased and then decreased with the increasing of seeding rate. From the views of nitrogen management, the nitrogen fertilization for heading sprouting of 40% (N2) would obtain the highest LAI during jointing stage. Adding the nitrogen fertilization for heading sprouting was beneficial to increase LAI after heading stage and promote photosynthetic rate, dry matter accumulation and nitrogen accumulation, enhance substance accumulation and turn-over capacity and nitrogen-absorption and nitrogen utilization efficiency under the seeding rates of 15.0 or 22.5 kg/hm2. Moreover, when the seeding rate was added up to 30.0 kg/hm2, through antedisplacement of nitrogen would avail the nutrient absorbability of rice and promote substance accumulation and turn-over capacity and improve the NUE. Correlation analysis indicated that both the photosynthetic efficiency and LAI during heading stage were significantly correlated with grain yield, nitrogen-absorbing ability and nitrogen-utilizing efficiency of rice plants.

In summary, when the seeding rate was 22.5 kg/hm2and the ratio of nitrogen application at transplanting stage, tillering stage and booting stage were 40%, 10%, and 50%, respectively, it would lead to gain the relatively high grain yield and higher photosynthetic efficiency, dry matter production capacity and nitrogen utilization efficiency.

seeding rate; nitrogen fertilizer management; photosynthetic productivity; nitrogen uptake; nitrogen use efficiency

農(nóng)業(yè)部作物生理生態(tài)與耕作重點(diǎn)實(shí)驗(yàn)室開(kāi)放課題(201303);國(guó)家“十二五”科技支撐計(jì)劃項(xiàng)目(2011BAD16B05;2012BAD04B13;2013BAD07B13);四川省科技支撐計(jì)劃項(xiàng)目(2013NZ0046;2014NZ0041;2014NZ0047);國(guó)家自然科學(xué)基金(31101117);四川省育種攻關(guān)專(zhuān)項(xiàng)(2011NZ0098-15)資助。

聯(lián)系方式:蔣明金(http://orcid.org/0000-0002-2081-543X),E-mail:mj_jiang2008@163.com

2015-07-10;接受日期(Accepted):2015-07-31;網(wǎng)絡(luò)出版日期(Published online):2015-09-18

S 511; S 352.2; S 143.1

A

*通信作者(Corresponding author):馬均(http://orcid.org/0000-0001-6103-5635),E-mail:majunp2002@163.com

URL:http://www.cnki.net/kcms/detail/33.1247.s.20150918.1745.006.html