李強， 馬曉君， 程秋博， 豆攀， 余東海， 羅延宏， 袁繼超， 孔凡磊*

(1.農業(yè)部西南作物生理生態(tài)與耕作重點實驗室/四川農業(yè)大學農學院，成都 611130; 2.眉山市東坡區(qū)農業(yè)技術推廣站，四川 眉山620032;3.四川省煙草公司宜賓市公司煙葉生產技術推廣應用中心，四川 宜賓644002)

氮肥對不同耐低氮性玉米品種干物質及氮素積累與分配的影響

李強1， 馬曉君1， 程秋博1， 豆攀1， 余東海2， 羅延宏3， 袁繼超， 孔凡磊1*

(1.農業(yè)部西南作物生理生態(tài)與耕作重點實驗室/四川農業(yè)大學農學院，成都 611130; 2.眉山市東坡區(qū)農業(yè)技術推廣站，四川 眉山620032;3.四川省煙草公司宜賓市公司煙葉生產技術推廣應用中心，四川 宜賓644002)

選用前期篩選出的玉米耐低氮品種正紅311和低氮敏感品種先玉508為試驗材料,采用裂區(qū)試驗在6個氮水平下研究不同耐低氮性玉米品種的生長發(fā)育、干物質及氮素積累與分配差異。結果表明:正紅311各階段干物質及氮素積累量和積累速率、各時期莖鞘和葉片干物質及氮素分配比例均高于先玉508,而先玉508雌穗干物質及氮素分配比例更高。與先玉508相比,正紅311提高了各主要生育時期葉片干物質及氮素積累量與分配比例,降低了雌穗干物質及氮素積累量與分配比例。正紅311營養(yǎng)器官較高的干物質及氮素積累與分配比例有利于其保持較高的養(yǎng)分吸收和干物質生產能力,延緩葉片的衰老和延長高光合速率使其產量顯著高于先玉508。施氮可顯著提高玉米株高、莖粗、葉面積、干物質積累、氮素吸收、產量及產量構成,而對干物質和氮素在各器官的分配比例影響較小。過量施氮不僅不利于玉米生長發(fā)育,還會使玉米收獲指數顯著降低，從而不利于產量的提高。正紅311施氮量在180 kg/hm2時產量最佳,而先玉508需要氮肥360 kg/hm2才能充分發(fā)揮其產量潛力。因此對于耐低氮品種正紅311可適當降低施氮量或在土壤貧瘠的丘陵山區(qū)種植以充分發(fā)揮其低氮條件下的產量優(yōu)勢,而低氮敏感品種先玉508則應適當增加施氮量或種植在肥沃土壤的地區(qū)以保證其高產穩(wěn)產。

氮肥； 玉米； 干物質； 積累與分配

隨著玉米生產的發(fā)展,玉米已逐漸成為我國種植面積第一的糧食作物[1]。西南地區(qū)作為我國玉米第二大主產區(qū),其玉米的高產穩(wěn)產對于我國糧食安全具有重要意義[2-4]。增施氮肥是提高玉米產量最直接也是最簡單的方式,所以農民在玉米生產中常常過量施用氮肥,不僅增加了玉米生產成本、降低氮肥利用效率,還造成資源浪費和環(huán)境污染問題[5-6]。因此,優(yōu)化施氮用量、提高氮素利用效率已成為我國玉米高產高效栽培的研究熱點[7-9]。前人研究表明,不同玉米品種對氮素的吸收利用特性差異顯著[8,10-11]；同一玉米品種在不同生態(tài)條件下對氮肥的響應也存在明顯的差異[12-16]。

不同耐低氮性玉米品種的物質生產與氮肥利用特性差異顯著,耐低氮玉米品種可以通過維持灌漿期綠葉面積來提高生育后期植株對氮素的吸收[10-11,17-19]。李文娟等[10]、崔超等[17]、陳范駿等[20]指出耐低氮玉米品種干物質積累量和氮素積累量均顯著高于低氮敏感品種,且這種差異主要來自吐絲后。前人對于不同耐低氮性玉米品種干物質及氮素積累差異做了較多研究[10,12,17,21],但主要集中于北方地區(qū)，單一氮肥水平下干物質和氮素積累量上的比較,少有涉及器官分配問題[8,10,17],且鮮見西南丘陵山區(qū)不同耐低氮性玉米品種的物質及氮素積累與分配利用差異的比較研究。本試驗在6個氮水平下,研究了不同耐低氮性玉米品種的干物質及氮素積累與分配特性,以期為西南丘陵山區(qū)根據玉米品種特性制定合理施氮技術提供理論依據。

1 材料與方法

1.1 試驗材料

前期試驗篩選出的耐低氮品種“正紅311”和低氮敏感品種“先玉508”[22-23]。

1.2 試驗時間與地點

2013年3—8月,四川省簡陽市蘆葭鎮(zhèn)英明村,位于東經104.53°，北緯30.38°N,海拔429 m,試驗期間氣象數據見圖1。

圖1 試驗期間氣象資料Fig.1 Meteorological data during the experimental period

1.3 試驗設計

采用裂區(qū)試驗設計,主區(qū)為品種,分別為耐低氮品種正紅311和低氮敏感品種先玉508；副區(qū)為施肥(純氮)水平,設0N-0 kg/hm2、90N-90 kg/hm2、180N-180 kg/hm2、270N-270 kg/hm2、360N-360 kg/hm2和450N-450 kg/hm2共6個水平,重復3次,共36個小區(qū),小區(qū)面積20 m2(長5 m,寬4 m)。供試土壤基礎肥力(0～20 cm):有機質16.60 g/kg,全氮1.24 g/kg,全磷0.73 g/kg,全鉀12.54 g/kg,堿解氮25.22 mg/kg,速效磷13.54 mg/kg,速效鉀138.75 mg/kg,pH 8.63。玉米直播(穴播3粒再定苗),單株栽培,行穴距為(1.5 m+0.5 m)×0.2 m,種植密度為50 000株/hm2。氮肥(尿素,46%)用量按底肥∶穗肥(攻苞肥)1∶1施用,另施過磷酸鈣600 kg/hm2、氯化鉀150 kg/hm2作底肥；其他栽培管理措施按當地高產要求進行,小區(qū)間保持一致。

1.4 植株取樣與測定

分別于玉米拔節(jié)期、吐絲期、灌漿期(吐絲后20 d)、成熟期每小區(qū)取代表性植株4株,先用長寬法測定葉面積,然后按器官(莖鞘、葉、雄穗和雌穗)分樣,于105 ℃下殺青30 min,然后80 ℃烘干至恒重稱量。

將烘干稱量后樣品用高速粉碎機粉碎,過80目篩后用塑封袋保存用于測定全氮含量。采用凱氏定氮法測定樣品全氮含量[24-25]。

統(tǒng)計收獲前每小區(qū)有效穗數、空稈率和雙苞率,各小區(qū)選取連續(xù)20株進行考種,考察穗長、穗粗、禿尖長、穗行數、行粒數、單穗質量、穗粒數、千粒質量等,然后分小區(qū)實收計產。

1.5 數據分析

采用Excel 2007和SPSS 20.0統(tǒng)計分析軟件進行數據處理和統(tǒng)計分析,并用LSD法進行差異顯著性檢驗,顯著水平設為P<0.05。

2 結果與分析

2.1 氮肥對不同耐低氮性玉米品種莖葉生長的影響

施用氮肥顯著影響玉米主要生育時期形態(tài)指標,且不同耐低氮性玉米品種形態(tài)指標對氮肥的響應差異顯著(表1)。耐低氮品種正紅311各時期株高、葉面積均顯著高于低氮敏感品種先玉508,其中正紅311各形態(tài)指標隨施氮量增加而先增后減,且在中高氮(270N、360N)水平下優(yōu)勢明顯；而先玉508各形態(tài)指標在試驗設計內隨施氮量增加而增加,在高氮(450N)處理下生長旺盛。與0N相比,施氮處理下耐低氮品種正紅311拔節(jié)期平均株高、莖粗、葉面積分別升高了6.9%、6.7%和6.0%,吐絲期分別升高了4.6%、1.5%和16.2%；低氮敏感品種先玉508拔節(jié)期分別升高了8.4%、4.2%和11.8%,吐絲期分別升高了5.7%、13.3%和43.0%。表明氮肥對低氮敏感品種先玉508形態(tài)指標的促進作用大于耐低氮品種正紅311,正紅311在中低氮水平下能更好地維持各形態(tài)指標的正常生長。從表1可以看出,玉米形態(tài)指標受品種類型和氮肥用量的影響顯著,且吐絲期株高受品種類型和施氮量互作影響顯著。

2.2 氮肥對不同耐低氮性玉米品種干物質積累與分配的影響

玉米生長過程主要包括營養(yǎng)生長期(播種—拔節(jié))、營養(yǎng)與生殖生長并進期(拔節(jié)—吐絲)和生殖生長期(吐絲—成熟)3個階段,2個供試品種在不同氮水平下各生育階段干物質積累量和生長率差異顯著(表2)。正紅311和先玉508干物質積累量和生長率均在吐絲—灌漿期最高,分別積累了全生育期干物質的30.2%和39.3%,耐低氮品種正紅311各階段干物質積累量和生長率均顯著高于低氮敏感品種先玉508,在生育后期(灌漿—成熟期)干物質積累和生長率正紅311較先玉508分別高出110.5%和110.9%。

表1 氮肥對玉米生長的影響

同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.*相關性顯著(P<0.05)；**相關性極顯著(P<0.01).

Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Single asterisk (*) and double asterisks (**) indicate significant correlations at the 0.05 and 0.01 probability levels， respectively.

表2 不同處理玉米主要生育階段干物質積累量和生長率

DMA:干物質積累量;CGR:作物生長率.同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.*相關性顯著(P<0.05)；**相關性極顯著(P<0.01).

DMA: Dry matter accumulation; CGR: Crop growth rate. Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Single asterisk (*) and double asterisks (**) indicate significant correlations at the 0.05 and 0.01 probability levels， respectively.

施氮顯著提高了玉米各階段的干物質積累量和生長率,2個品種平均播種—拔節(jié)期、拔節(jié)—吐絲期、吐絲—灌漿期和灌漿—成熟期5個氮肥處理平均干物質積累量分別較對照高17.6%、18.9%、51.7%和15.0%,以吐絲—灌漿期的促進作用最大。進一步分析發(fā)現(xiàn),氮肥對2個參試品種各生育時期干物質積累量和生長率的影響程度和規(guī)律不盡一致,總體而言,耐低氮正紅311各生育階段的干物質積累量隨氮肥水平的增加先增后降,而耐肥品種先玉508則隨氮肥水平的增加呈增加趨勢,尤其是生育后期。耐低氮品種正紅311吐絲—成熟期和全生育期(即成熟期)單株干物質積累量(y)與施氮量(x)之間呈二次凸函數關系,回歸方程分別為y=122.26+0.398 3x-0.000 502x2(R2=0.973 0**)和y=234.49+0.523 1x-0.000 675x2(R2=0.973 3**),分別在396.7 kg/hm2和387.4 kg/hm2最高,而耐肥品種先玉508吐絲—成熟期和全生育期(即成熟期)單株干物質積累量(y)與施氮量(x)之間呈一次函數關系,回歸方程分別為y=105.78+0.104 6x(R2=0.947 8**)和y=202.76+0.146 3x(R2=0.936 7**),在試驗處理范圍內以氮肥水平450 kg/hm2為最高。

品種類型和氮肥施用對玉米干物質積累與分配影響顯著,且品種類型的影響顯著高于氮肥施用(表3)。耐低氮品種正紅311吐絲期和成熟期干物質積累均顯著高于低氮敏感品種先玉508,分別高出19.9%和28.2%,表明隨生育進程2個品種干物質積累差異加大。施氮顯著提高了2個品種吐絲期和成熟期的干物質積累,與0N相比,正紅311吐絲期和成熟期在施氮處理下干物質積累平均分別升高了14.3%和32.2%,而先玉508升高了21.8%和23.2%,表明施氮有利于先玉508生育前期干物質積累,而對正紅311生育后期干物質積累促進作用較大。

吐絲期和成熟期正紅311營養(yǎng)器官(莖鞘、葉片)干物質分配比例均顯著高于先玉508,表明正紅311較先玉508具有更高的干物質生產能力。施氮顯著影響玉米成熟期葉片及雌穗干物質分配,而對莖鞘干物質分配影響不顯著。與0N相比,2個供試品種各施氮處理成熟期葉片干物質分配比例平均下降了11.5%,雌穗分配比例升高了3.8%,表明施氮可降低成熟期葉片的干物質分配比例以提高向雌穗的分配，從而提高產量。氮肥對玉米葉片干物質分配比例的影響表現(xiàn)出隨施氮量增加而先增后減的趨勢,在270N處理下葉片干物質分配比例降幅最大,雌穗干物質分配比例增幅最大。因此,合理施用氮肥可以降低成熟期葉片分配比例,增加雌穗分配比例,但過量施用氮肥致葉片分配比例有所上升反而不利于雌穗干物質分配的提高。

表3 不同處理玉米各時期單株干物質及在葉片、莖鞘和穗分配情況

同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.**相關性極顯著(P<0.01).

Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Double asterisk (**) indicates highly significant correlation at the 0.01 probability level.

2.3 氮肥對不同耐低氮性玉米品種氮素積累與分配的影響

品種類型和氮肥施用對玉米各階段氮素積累量和積累速率影響顯著(表4)。從全生育期來看,正紅311的氮素積累總量高于先玉508,平均高23.3%,表明正紅311有更強的氮素吸收能力,這可能是其耐低氮的主要機制。從各生育階段來看,2個供試品種氮素積累量均在播種—拔節(jié)期最高,拔節(jié)—吐絲期最低；正紅311氮素積累速率在播種—拔節(jié)期最低,而先玉508在播種—拔節(jié)期最高；表明先玉508氮素積累高峰出現(xiàn)在營養(yǎng)生長期(播種—拔節(jié)期),而正紅311氮素積累高峰在營養(yǎng)生長與生殖生長并進期(拔節(jié)—吐絲期),且在生殖生長期(吐絲—成熟期)也保持較高的氮素積累速率。生育中后期(拔節(jié)—成熟期)正紅311氮素積累量和積累速率均顯著高于先玉508,而在生育早期2個品種氮素積累量和積累速率差異不顯著,表明2類品種氮素積累差異主要由生育中后期氮素積累差異引起。

氮肥水平顯著影響2個品種各生育階段的氮素吸收積累量和積累速率,在吐絲前,2個品種的氮素積累量均隨施氮量的增加而呈先增后減趨勢,二者之間呈極顯著的二次凸函數關系；但吐絲后的氮素積累量則均隨施氮量的增加而呈增加趨勢,二者間呈顯著正相關關系,其中正紅311隨施氮水平增加的增幅大大高于先玉508。

表4 玉米不同氮水平下主要生育階段氮素積累量和積累速率

NA:氮素積累量;NAR:氮素積累速率.同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.**相關性極顯著(P<0.01).

NA: Nitrogen accumulation; NAR: Nitrogen accumulation rate. Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Double asterisk (**) indicates highly significant correlation at the 0.01 probability level.

養(yǎng)分在植株各器官的積累分配是植株生長發(fā)育的物質基礎,結果(表5)表明，玉米吐絲期葉片氮素積累量最高,占總氮素積累量50%左右,而成熟期75%以上的氮素均集中在雌穗。不同耐低氮性玉米品種氮素積累量差異顯著,耐低氮品種正紅311吐絲期和成熟期單株氮積累量較低氮敏感品種先玉508分別高22.1%和22.6%；表明正紅311較先玉508具有更強的氮素吸收能力,在低氮條件下可保持較高的氮素吸收積累，提高其對低氮環(huán)境的適應能力。

品種類型和施用氮肥對氮素在玉米植株中的分配影響顯著(表5)。耐低氮品種正紅311的2個時期葉片氮素分配比例均高于低氮敏感品種先玉508,而雌穗氮素分配比例則低于先玉508。施氮顯著影響成熟期葉片和莖鞘的氮素分配比例,與0N相比,2個品種各施氮處理成熟期葉片氮素分配比例平均下降了4.7%,而莖鞘氮素分配比例升高了10.8%?？梢?品種類型引起的玉米植株氮素分配差異顯著大于氮肥施用,而氮肥施用對玉米生育后期氮素分配比例的影響大于生育中前期,且氮肥施用主要影響葉片和莖鞘的氮素分配,對雌穗氮素分配影響不大。

2.4 氮肥對不同耐低氮性玉米品種穗部性狀及產量的影響

品種類型和施氮水平對玉米產量及其構成影響顯著(表6)。耐低氮品種正紅311穗長、穗粗、穗粒數、千粒質量和產量均高于低氮敏感品種先玉508,而收獲指數低于先玉508。氮肥水平對2個品種的產量及其構成因素均有顯著影響,增施氮肥可以改善穗部性狀,增加穗粒數和千粒質量,從而提高玉米的產量。玉米的產量(y)隨施氮量(x)的增加先迅速提高,之后逐漸趨于穩(wěn)定甚至降低,二者之間符合肥力-產量模型,正紅311和先玉508的回歸方程分別為y=x/(0.013 215+0.000 685x)+6 755.96(R2=0.921 3*)和y=x/(0.019 042+0.001 213x)+6 395.79(R2=0.933 3*),正紅311氮肥水平180 kg/hm2左右時產量最高,而先玉508在360 kg/hm2時產量最高,耐低氮品種正紅311適宜的氮肥水平較低,而耐肥品種先玉508適宜的氮肥水平較高。

表5 不同氮水平下玉米單株氮積累量及在葉片、莖鞘和穗分配情況

同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.*相關性顯著(P<0.05)；**相關性極顯著(P<0.01).

Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Single asterisk (*) and double asterisks (**) indicate significant correlations at the 0.05 and 0.01 probability levels， respectively.

表6 施氮量對玉米產量、穗部性狀及產量構成的影響

同列數據后的不同小寫字母表示同一項目不同處理間在P<0.05水平差異有統(tǒng)計學意義.*相關性顯著(P<0.05)；**相關性極顯著(P<0.01).

Values within a column followed by different lowercase letters show significantly differences of the same item among different treatments at the 0.05 probability level. Single asterisk (*) and double asterisks (**) indicate significant correlations at the 0.05 and 0.01 probability levels， respectively.

3 討論

干物質和養(yǎng)分的積累與分配是作物器官分化、產量形成的前提,養(yǎng)分吸收是干物質形成和積累的基礎[26-27]。春亮等[8]、崔超等[10]、李文娟等[17]研究表明不同耐低氮性玉米品種干物質和氮素積累差異主要來自吐絲后,而在生育前期差異不顯著。本試驗結果表明,耐低氮品種正紅311“源豐、流暢、庫足”葉面積、莖粗和穗部性狀均明顯優(yōu)于低氮敏感品種先玉508,使其各階段干物質積累量和積累速率均高于低氮敏感品種先玉508,但2個品種干物質積累差異主要來自生育后期。施用氮肥顯著增加了玉米各階段的干物質積累,過量施氮可增加生育前期植株葉面積,延緩生育后期葉片的衰老。耐低氮品種正紅311各主要生育時期葉片干物質積累量與分配比例均顯著高于低氮敏感品種先玉508,較高的營養(yǎng)器官分配比例有利于耐低氮品種正紅311更好地進行光合作用,積累更多的干物質和養(yǎng)分供生殖器官生長發(fā)育。施氮顯著增加了玉米各器官的干物質積累量和成熟期葉片、雌穗的干物質分配比例,而對莖鞘干物質分配比例的影響不顯著。

花前積累氮素的再活化和花后氮素的積累是籽粒氮素的根本來源[28-29]。隨著生育進程的推進玉米氮素積累在不同器官中差異明顯,開花前主要集中在營養(yǎng)器官,而花后不斷向生殖器官轉移[30-31]。葉利庭等[9]、崔超等[10]研究得出不同耐低氮性品種籽粒氮素積累差異主要來自吐絲后氮素的合成量。本試驗結果表明,耐低氮品種正紅311各階段氮素積累量和積累速率均高于低氮敏感品種先玉508,但拔節(jié)前2個品種氮素積累差異不顯著,2個品種氮素積累差異主要來自生育中后期,這與李文娟等[17]、戢林等[28]的研究結果一致。施氮顯著提高了玉米各主要生育階段的氮素積累,但不同階段對氮素的響應不同。吐絲前玉米氮素積累量隨施氮量的增加而先增后減,吐絲后則表現(xiàn)為隨施氮量增加而增加；表明玉米生育前期土壤養(yǎng)分充足對氮肥的需求相對較低,過量施氮不利于氮素的吸收,而生育后期土壤養(yǎng)分耗竭,過量施氮可以進一步提高氮素的積累。耐低氮品種正紅311成熟期莖鞘和葉片較高的干物質積累使其成熟期各器官的氮素積累量和葉片、莖鞘氮素分配比例均顯著高于低氮敏感品種先玉508,而雌穗氮素分配比例低于先玉508。施氮顯著提高了玉米主要生育時期各器官的氮素積累量,但對各器官氮素分配比例影響不大。

玉米產量主要取決于吐絲后籽粒形成過程中植株光合產物的生產能力及向籽粒的分配。研究表明[8,10,17,28]在不同氮水平下耐低氮品種較低氮敏感品種均有較大的產量優(yōu)勢。本試驗結果表明,耐低氮品種正紅311吐絲后干物質積累和氮素吸收顯著高于低氮敏感品種先玉508,產量較先玉508提高8.8%,且產量最高的適宜施氮水平正紅311顯著低于先玉508,與前人[10,17]研究結果一致。施氮顯著改善了玉米穗部性狀和產量構成因素,進而提高了產量,但高氮水平下玉米產量差異不顯著,同時玉米收獲指數隨施氮量增加而顯著降低,因此過量施氮不僅不能提高玉米產量還會降低玉米收獲指數而導致產量降低,這與景立權等[30]研究結果一致。耐低氮品種正紅311在穗部性狀及產量構成上較低氮敏感品種先玉508均有一定優(yōu)勢,但先玉508的收獲指數更高,可能是由于低氮敏感品種先玉508吐絲后光合生產能力和養(yǎng)分吸收低無法滿足籽粒物質及養(yǎng)分需求,加大了其營養(yǎng)器官干物質與氮素的轉運,從而降低了成熟期葉片和莖鞘的干物質與氮素分配比例,提高了收獲指數。

4 結論

耐低氮品種正紅311各階段干物質及氮素積累量和積累速率、各時期莖鞘和葉片干物質及氮素分配比例均高于低氮敏感品種先玉508,而先玉508雌穗干物質及氮素分配比例更高。耐低氮品種正紅311營養(yǎng)器官較高的干物質及氮素分配比例有利于其保持較高的養(yǎng)分吸收和干物質生產能力,延緩葉片的衰老和延長高光合速率。較高的干物質積累和養(yǎng)分吸收使耐低氮品種正紅311產量及產量構成均明顯優(yōu)于低氮敏感品種先玉508,而先玉508較高的雌穗干物質及氮素分配比例使其收獲指數顯著高于正紅311。施氮可以顯著提高玉米的株高、莖粗、葉面積、干物質積累、氮素吸收、玉米穗部性狀、產量及產量構成,而對干物質和氮素在各器官的分配比例影響較小。過量施氮不僅不利于玉米生長發(fā)育,還會使玉米收獲指數顯著降低從而不利于產量的提高。正紅311耐低氮,適宜中低氮水平或種植在土壤貧瘠的丘陵區(qū)以充分發(fā)揮其低氮條件下的產量優(yōu)勢,而先玉508耐肥水則應適當增加施氮量或種植在土壤肥沃的地區(qū)以保證其高產穩(wěn)產。

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Effects of nitrogen fertilizer on the accumulation and allocation of dry matter and nitrogen for maize cultivars with different low nitrogen tolerance。

Journal of Zhejiang University (Agric. & Life Sci.)， 2015，41(5):527-536

Li Qiang1, Ma Xiaojun1, Cheng Qiubo1, Dou Pan1, Yu Donghai2, Luo Yanhong3, Yuan Jichao1, Kong Fanlei1*

(1.KeyLaboratoryofCropEcophysiologyandFarmingSysteminSouthwestChina,MinistryofAgriculture/CollegeofAgronomy,SichuanAgriculturalUniversity,Chengdu611130,China; 2.DongpoAgricultureTechnologyExtensionStation,Meishan620032,Sichuan,China; 3.TobaccoProductionTechnologyofDisseminationandApplyofYibinTobaccoCorporationinSichuan,Yibin644002,Sichuan,China)

Nitrogen is a major limiting factor on plant growth and yield formation, and a moderate amount of nitrogen fertilizers can increase crop yields every year. The tolerance to low N-fertilized level is different among maize cultivars, meanwhile the response of different maize cultivars are also significantly different under different N-fertilized levels. What’s more, different maize cultivars have significant difference in the dry matter production and nitrogen utilization efficiency. Related researches indicate that dry matter and nitrogen accumulation of low nitrogen tolerant maize cultivars were remarkable higher than that of low nitrogen sensitive maize cultivars, besides, low nitrogen tolerant maize cultivars had larger green leaf areas to increase the nitrogen absorption in the late growth stage, and the difference of those in two types maize cultivars is mainly performed after the silking stage.

A split plot experiment using the screened maize cultivars Zhenghong 311 with low nitrogen tolerance and Xianyu 508 with low nitrogen sensitivity as materials was conducted to investigate the difference of growth and development, dry matter and nitrogen accumulation and allocation in different low nitrogen tolerant maize cultivars under six nitrogen levels, and the different maize cultivars (Zhenghong 311 and Xianyu 508) were used as main plot and nitrogen fertilization rate (0N-0 kg/hm2, 90N-90 kg/hm2, 180N-180 kg/hm2, 270N-270 kg/hm2, 360N-360 kg/hm2and 450N-450 kg/hm2, 50% base fertilizer and 50% panicle fertilizer) were used as sub-plot. The aims were to provide the theoretical and practical data for the reasonable nitrogen management of different low nitrogen tolerant maize cultivars in hilly areas.

The results showed that the accumulation and allocation of dry matter and nitrogen in stem-sheath and leaf of low nitrogen tolerant Zhenghong 311 were higher than that of low nitrogen sensitivity Xianyu 508 in all stages, while the dry matter and nitrogen allocation ratio of panicle in Xianyu 508 were higher. Compared with low nitrogen sensitive cultivar, low nitrogen tolerant cultivar increased the accumulation and allocation ratio of dry matter and nitrogen in leaf, and reduced that in panicle. The higher dry matter and nitrogen accumulation and allocation ratio of vegetative organs in low nitrogen tolerant cultivar were beneficial to keep higher nutrition absorption and dry matter productivity, and the yield of Zhenghong 311 was significantly higher than Xianyu 508 because the Zhenghong 311 delayed the senescence of leaf and prolonged the time of high photosynthesis rate under low nitrogen tolerant stress. Nitrogen fertilization significantly increased plant height, stem diameter, leaf area, dry matter accumulation, nitrogen absorption, yield and yield component, while the effect of nitrogen fertilization on the allocation ratio in dry matter and nitrogen were slight. Excessive nitrogen was not conducive to the growth and development of maize, meanwhile it reduced the harvest index that go against the increase of yield.

It is concluded that the low nitrogen tolerant cultivar Zhenghong 311 has higher dry matter and nitrogen accumulation to keep higher yield under low nitrogen levels, while the low nitrogen sensitive cultivar Xianyu 508 needs higher nitrogen fertilizer to get higher yield. Therefore, we can reduce nitrogen fertilization for low nitrogen tolerant cultivar Zhenghong 311 or plant it in poor soil of hilly region to make good use of the yield advantage under low nitrogen environment. On the contrary, the nitrogen fertilization of the low nitrogen sensitive cultivar Xianyu 508 should be increased or planted in a fertile region to guarantee its high stable yield.

nitrogen fertilizer; maize; dry matter; accumulation and allocation

公益性行業(yè)(農業(yè))科研專項經費項目(201503127);國家“十二五”科技支撐計劃項目(2012BAD04B13)；四川省科技支撐計劃項目(2014NZ0040)；四川省玉米產業(yè)技術體系崗位專家項目。

聯(lián)系方式:李強(http://orcid.org/0000-0003-2115-0158)，E-mail:liqiangxj@163.com

2015-05-15;接受日期(Accepted):2015-07-05；網絡出版日期(Published online):2015-09-18

S 513

A

*通信作者(Corresponding author):孔凡磊(http://orcid.org/0000-0003-4131-0606)，E-mail:kflstar@163.com

URL:http://www.cnki.net/kcms/detail/33.1247.s.20150918.1747.008.html