鞏若琳 宋 波 楊志葉 路麗靜 董軍剛

遲播和密度對不同油菜品種抗倒伏及產(chǎn)量的影響

鞏若琳 宋 波 楊志葉 路麗靜 董軍剛*

西北農(nóng)林科技大學(xué)農(nóng)學(xué)院, 陜西楊凌 712100

研究遲播和密度對油菜抗倒伏及產(chǎn)量的影響, 為油菜機械化生產(chǎn)提供理論及技術(shù)支撐。以陜油28、秦優(yōu)28及秦優(yōu)7號為供試品種, 分別設(shè)置3個播期(T1: 9月24日、T2: 10月1日、T3: 10月8日)和3個密度(D1: 22.5萬株 hm–2、D2: 45.0萬株 hm–2、67.5萬株 hm–2)處理, 分析其產(chǎn)量及構(gòu)成因素、倒伏相關(guān)指標、莖稈主要成分含量及顯微結(jié)構(gòu)等指標。結(jié)果表明: (1) T1、T2下, 隨種植密度增加, 3個品種單株產(chǎn)量均下降, 群體產(chǎn)量均先增后降, 倒伏指數(shù)均先降后增, 維管束與莖稈橫截面積均下降, 維管束面積/莖稈橫截面積、莖稈木質(zhì)素與纖維素含量均先增后降, D2時群體產(chǎn)量最大, 倒伏指數(shù)最小, 產(chǎn)量與抗倒伏能力協(xié)同增加。遲播條件(T3)下, 隨密度增加, 3個品種單株產(chǎn)量、倒伏指數(shù)、莖稈木質(zhì)素及纖維素含量、地上部鮮重、維管束面積及莖稈橫截面積及二者之比均顯著下降, 群體產(chǎn)量及抗倒性增強, 木質(zhì)素含量與莖稈抗倒伏能力顯著正相關(guān), 群體產(chǎn)量及材料抗倒能力在D3時達最大值。與正常播期(T1)相比, 遲播條件(T3)下, 各密度下, 3個品種單株角果數(shù)、每角粒數(shù)、單株產(chǎn)量及群體產(chǎn)量、地上鮮重、倒伏指數(shù)均顯著下降, 但抗倒伏能力增強。(2) 正常播期(T1)下, 3個品種群體產(chǎn)量最高時, 種植密度均為45.0萬株 hm–2。遲播(T3)后, 密度67.5萬株 hm–2時3個品種產(chǎn)量均最高, 其中陜油28的耐密性與耐遲播性最佳。綜上所述, 遲播條件下, 選擇耐密及耐遲播品種, 并適度增加密度, 可彌補單產(chǎn)不足, 顯著提高莖稈木質(zhì)素及纖維素含量、增強油菜抗倒伏能力, 有效協(xié)調(diào)高產(chǎn)與倒伏間的矛盾, 通過以密補遲實現(xiàn)遲播油菜高產(chǎn)抗倒。

油菜; 播期; 密度; 產(chǎn)量; 抗倒性

油菜是我國第二大油料作物, 種植面積達676.42萬公頃[1], 2021年我國國產(chǎn)油料榨油量為1234.8萬噸, 占全國食用油消費總量的29.0%, 是我國重要的食用油來源[2]。隨前茬作物收獲時期推遲, 直播油菜茬口矛盾更加突出, 加之氣候因素(如降雨)等影響,油菜遲播現(xiàn)象日趨嚴重。同時, 倒伏現(xiàn)象在油菜生產(chǎn)上頻繁產(chǎn)生, 限制油菜機械化生產(chǎn)與經(jīng)濟效益提高。因此, 研究遲播對油菜抗倒伏性及產(chǎn)量影響的作用機制, 對遲播油菜生產(chǎn)效益的提高具有重要的參考意義。

適度遲播可縮短油菜生育期, 降低株高, 減少分枝數(shù), 增加分枝高度, 有利于機械化收獲[3]。同時遲播對于控制根腫病的發(fā)生與抑制植株旺長具有一定的效果[4]。但遲播條件下, 油菜冬前生長量不足, 莖稈抗折力較弱, 各產(chǎn)量構(gòu)成因素不協(xié)調(diào)導(dǎo)致產(chǎn)量降低, 因此, 可通過增加種植密度提高群體優(yōu)勢彌補油菜個體不足, 提高遲播油菜產(chǎn)量[5]。

種植密度是協(xié)調(diào)作物個體與群體、高產(chǎn)與抗倒的重要因素。合理密植是提高油菜產(chǎn)量和經(jīng)濟效益的重要途徑。適度增加種植密度可有效發(fā)揮群體優(yōu)勢, 改變植株株型及冠層結(jié)構(gòu), 提高光能利用率, 增加群體產(chǎn)量。但密度過大, 油菜倒伏風(fēng)險也顯著增加[6]。田間倒伏導(dǎo)致油菜抵抗非生物脅迫能力、抗病蟲害能力和籽粒品質(zhì)均下降, 阻礙機械化收獲的開展, 降低油菜的經(jīng)濟效益[7]。作物抗倒伏能力受基因型、株高、莖稈顯微結(jié)構(gòu)和化學(xué)組成等影響[8]。其中纖維素微纖絲可影響細胞結(jié)構(gòu)和強度; 木質(zhì)素可增大莖稈硬度、增加莖稈壁厚與強化抗壓能力[9-10],因此木質(zhì)素與纖維素是影響作物莖稈抗倒伏的關(guān)鍵物質(zhì)[11-13]。適當增加種植密度, 油菜莖稈中木質(zhì)素、纖維素合成關(guān)鍵酶基因的表達量增加, 木質(zhì)素、纖維素合成關(guān)鍵酶活性升高, 木質(zhì)素、纖維素含量增加, 油菜抗倒性增強[5]。適宜的播期和密度下, 油菜生育期適宜, 植物體內(nèi)各營養(yǎng)元素含量較高, 個體及群體產(chǎn)量與抗倒性之間的矛盾較為協(xié)調(diào), 品質(zhì)產(chǎn)量與抗倒能力均提高。

前人對油菜抗倒伏的研究, 主要集中在倒伏特性[14]、莖稈生化成分[15-17]等植物生理與分子生物層面上, 但很少研究遲播與密度互作下, 油菜抗倒伏能力及其與產(chǎn)量的關(guān)系?；诖? 本研究對油菜不同品種設(shè)置不同播期和密度處理, 從農(nóng)藝性狀、莖稈生化成分及顯微結(jié)構(gòu)等層面進行較為系統(tǒng)的研究,以期為遲播油菜高產(chǎn)抗倒伏栽培技術(shù)提供支持。

1 材料與方法

1.1 試驗設(shè)計

2019—2021連續(xù)2年在西北農(nóng)林科技大學(xué)油菜育種實驗基地(34.30°N, 108.06°E)進行。前茬作物為小麥, 試驗地為塿土, 有機質(zhì)1.76 g kg–1, 全氮0.11 g kg–1, 全磷0.13 g kg–1, 速效磷23.50 mg kg–1, 速效鉀236.72 mg kg–1。試驗采用三因素裂區(qū)試驗設(shè)計, 以播期為主區(qū), 密度為裂區(qū), 品種為再裂區(qū), 播期設(shè)置為9月24日(T1)、10月1日(T2)、10月8日(T3); 密度設(shè)置為D1 (22.5萬株 hm–2)、D2 (45.0萬株 hm–2)、D3 (67.5萬株 hm–2); 品種為陜油28 (Shaanyou 28, S28)、秦優(yōu)28 (Qinyou 28, Q28)、秦優(yōu)7號(Qinyou 7, Q7); 3次重復(fù), 共計81個小區(qū)。小區(qū)面積為10 m2(2 m × 5 m)。播種方式為直播, 基肥施用復(fù)合肥(N∶P2O5∶K2O為15%∶15%∶15%) 375 kg hm-2及硼肥15 kg hm-2, D1密度行距為40 cm, D2和D3密度行距為30 cm, 三葉期間苗, 五葉期定苗, 其他田間管理方法同大田油菜管理一致, 于次年5月20日左右收獲。

1.2 測定指標與方法

1.2.1 氣象數(shù)據(jù) 氣象數(shù)據(jù)源于中國氣象數(shù)據(jù)網(wǎng)(http://data.cma.cn/): 地面氣候資料日值數(shù)據(jù)集楊凌站。

1.2.2 農(nóng)藝性狀、產(chǎn)量與產(chǎn)量構(gòu)成調(diào)查 于油菜各主要生育期(初花期、盛花期、終花期、角果期、成熟期)記錄各植株發(fā)育情況并取樣, 成熟期測定農(nóng)藝性狀及產(chǎn)量。測量的農(nóng)藝性狀主要包括株高、根頸粗、分枝部位高度等, 測定的產(chǎn)量性狀包括單株角果數(shù)、每角果粒數(shù)、千粒重等, 小區(qū)單獨收獲并測產(chǎn)。取樣時隨機選取長勢與本小區(qū)長勢一致的5個單株, 3次重復(fù)。

1.2.3 倒伏相關(guān)指標 成熟期各小區(qū)取樣, 用YYD-1莖稈強度測量儀(浙江托普儀有限公司)測定油菜根頸以上30～40 cm區(qū)段抗折力。倒伏指數(shù)(Lodging Index, LI, 單位: cm g N–1) = 鮮重(g) × 高度(cm)/抗折力(N)[18]。此處高度和鮮重為測定莖段至植株頂部對應(yīng)高度及鮮重。

1.2.4 莖稈化學(xué)成分 將花期主莖樣品分裝入玻璃瓶中, 烘箱85℃烘干至恒重, 粉碎過篩, 測定木質(zhì)素及纖維素含量。采用溴乙酰法[19]測定木質(zhì)素含量, 采用王玉萬等[20]的方法測定纖維素含量。

1.2.5 莖稈顯微結(jié)構(gòu)測定 木質(zhì)素單體中含有酚酸類物質(zhì), 酚酸類物質(zhì)在熒光下可自發(fā)熒光, 通過將莖稈切片放置于熒光顯微鏡下綠色熒光激發(fā), 觀測切片自發(fā)熒光情況即可了解不同品種中木質(zhì)化部位分布差異[21]。本試驗在花期取距離根頸35 cm處的莖稈10 cm, 置于FAA固定液中, 用番紅固綠染色后制作石蠟切片, 用奧林巴斯全自動正置熒光顯微鏡(BX63)觀察并掃描所制的切片。

1.3 數(shù)據(jù)處理

數(shù)據(jù)經(jīng)Microsoft Excel軟件整理后, 采用SPSS 26.0軟件進行方差分析, 試驗結(jié)果多重比較采用最小顯著差法(Least-significant difference, LSD), 顯著水平均為0.05; 采用Origin 2021軟件繪圖。

2 結(jié)果與分析

2.1 不同播期和密度下油菜生育期及氣象因子差異

油菜生育期的降雨量、有效積溫及光照輻射在2019—2020與2020—2021兩年間存在差異(表1和圖1)。與2019—2020年相比, 2020—2021年有效積溫減少, 總降雨量增加。2019—2020年生育期光照輻射強度為876.31 kW m–2, 比2020—2021年高出82.09 kW m–2。同一密度, 播期延后, 全生育期縮短15 d左右。同一播期, 密度增加, 生育期縮短2～4 d, 3個品種規(guī)律一致。相同處理下, 所需有效積溫表現(xiàn)為秦優(yōu)7號>陜油28>秦優(yōu)28; 9月24日(T1)播期的有效積溫高于10月1日(T2)與10月8日(T3)。

圖1 2019–2021年油菜生育期太陽輻射日變化

表1 2019-2021年油菜生育期及氣象數(shù)據(jù)

D1、D2和D3分別表示種植密度為22.5萬株 hm–2、45.0萬株 hm–2和67.5萬株 hm–2。T1、T2和T3分別表示9月24日、10月1日和10月8日播種時間。S28、Q28和Q7分別表示品種為陜油28、秦優(yōu)28和秦優(yōu)7號。

D1, D2, and D3 indicate the planting densities of 22.5×104, 45.0×104, and 67.5×104plants hm–2, respectively. T1, T2, and T3 represent sowing time on Sep. 24, Oct.1, and Oct. 8, respectively. S28, Q28, and Q7 represent varieties of Shaanyou 28, Qinyou 28, and Qinyou 7, respectively.

2.2 不同播期和密度對不同油菜品種農(nóng)藝性狀的影響

同一播期下, 密度增加, 3個品種的根頸粗、株高、主花序長度、地上干重及地下干重均呈下降趨勢, 分枝高度隨密度的增加呈上升趨勢; 同一密度下,播期延后, 3個品種的根頸粗、株高、主花序長度、地上干重及地下干重均呈下降趨勢, 分枝高度呈先降后升的趨勢, 2年結(jié)果一致(表2)。本試驗中, 秦優(yōu)7號在同一處理下分枝高度、株高和主花序長度高于其余2個品種; 陜油28的株高與主花序長度在3個品種中最低。播期、密度和品種對根頸粗、株高、分枝高度、主花序長度、地下干重均具有顯著影響。

表2 不同播期和密度對油菜農(nóng)藝性狀的影響

(續(xù)表2)

同列標以不同小寫字母表示0.05概率水平差異顯著。*、**表示在0.05和0.01概率水平差異顯著, NS表示差異不顯著。V×T、V×D、T×D和V×T×D分別表示因素間互作?？s寫同表1。

Values followed by different lowercase letters within a column are significantly different at the 0.05 probability level. * and ** indicate significant difference at the 0.05 and 0.01 probability levels, respectively. NS: not significant difference; T: sowing date; V: variety; D: density; V×T, V×D, T×D, and V×T×D mean the interaction between factors, respectively. Abbreviations are the same as those given in Table 1.

2.3 不同播期和密度對油菜產(chǎn)量及倒伏性狀的影響

2.3.1 產(chǎn)量及產(chǎn)量構(gòu)成 同一播期, 密度增加, 3個品種的單株角果數(shù)、每角粒數(shù)均下降, 千粒重?zé)o顯著性變化。密度增加至67.5萬株 hm–2, 單株產(chǎn)量下降62.25%, 3個播期平均產(chǎn)量表現(xiàn)為T1>T2>T3; 同一密度, 播期延后, 3個品種的單株角果數(shù)、每角粒數(shù)與千粒重均下降, 單株產(chǎn)量下降39.43%, 2年結(jié)果一致(表3)。小區(qū)產(chǎn)量在播期和密度間有所不同。9月24日(T1)及10月1日(T2)處理下, 小區(qū)產(chǎn)量隨著密度的增加呈先增后減的趨勢; 10月8日(T3)處理下, 小區(qū)產(chǎn)量隨密度的增加而增加, 3個品種、2年度間規(guī)律相近。不同密度處理下, 3個品種、2年度間規(guī)律一致。品種、播期及密度對單株角果數(shù)、每角粒數(shù)、千粒重、單株產(chǎn)量及小區(qū)產(chǎn)量的影響均達到了顯著水平。

2.3.2 倒伏相關(guān)性狀 同一播期, 密度增大, 3個品種莖稈抗折力和地上鮮重均顯著下降。T1、T2處理下, 陜油28和秦優(yōu)7號的倒伏指數(shù)在密度為D2時達到最小值, 秦優(yōu)28的倒伏指數(shù)在密度為D3時達到最小值; T3處理下, 3個品種倒伏指數(shù)均在D3時達到最小值; 同一密度, 播期推遲, 3個品種莖稈抗折力和地上部鮮重均顯著下降, 倒伏指數(shù)下降; 相同條件下, 陜油28的倒伏指數(shù)低于秦優(yōu)28和秦優(yōu)7號, 2年規(guī)律一致(圖2)。播期、密度和品種對莖稈抗折力、地上鮮重和倒伏指數(shù)影響均達到顯著水平。

表3 不同播期和密度對油菜產(chǎn)量及產(chǎn)量構(gòu)成的影響

(續(xù)表3)

同列標以不同小寫字母表示0.05概率水平差異顯著。*、**表示在0.05和0.01概率水平差異顯著, NS表示差異不顯著。V×T、V×D、T×D和V×T×D分別表示因素間互作?？s寫同表1。

Values followed by different lowercase letters within a column are significantly different at the 0.05 probability level. * and ** indicate significant difference at the 0.05 and 0.01 probability levels, respectively. NS: not significant difference; T: sowing date; V: variety; D: density; V×T, V×D, T×D, and V×T×D mean the interaction between factors, respectively. Abbreviations are the same as those given in Table 1.

圖2 不同播期和密度對油菜莖稈抗折力、鮮重和倒伏指數(shù)的影響

不同小寫字母表示在0.05概率水平差異顯著。*、**表示在0.05和0.01概率水平差異顯著, NS表示差異不顯著。T: 播期; V: 品種; D: 種植密度; V×T、V×D、T×D和V×T×D分別表示因素間互作。縮寫同表1。

Different lowercase letters indicate significant differences at the 0.05 probability level. * and ** indicate significant difference at the 0.05 and 0.01 probability levels, respectively. NS: not significant difference; T: sowing date; V: variety; D: density; V×T, V×D, T×D, and V×T×D mean the interaction between factors, respectively. Abbreviations are the same as those given in Table 1.

2.4 播期和密度對莖稈結(jié)構(gòu)的影響

2.4.1 播期和密度對莖稈顯微結(jié)構(gòu)的影響 播期對油菜莖稈橫截面及維管束面積大小及占比的影響見圖3和圖4。結(jié)果表明, 播期推遲, 3個品種油菜莖稈橫截面分別減少77.19、56.90和53.08 mm2, 維管束面積分別減少14.55、12.24和10.14 mm2, 且維管束在莖稈橫截面中的面積占比減少2.54%、3.02%和2.66%。種植密度對油菜橫截面及各組織區(qū)域面積大小及占比的影響如圖3和圖4所示, 密度增大, 3個品種油菜莖稈橫截面分別減少16.79、13.86和11.83 mm2, 維管束面積分別減少80.01、55.76和59.44 mm2, 且維管束在莖稈橫截面中的面積占比減少3.70%、4.08%和3.33%。成熟期木質(zhì)部面積結(jié)構(gòu)如圖5所示。木質(zhì)化面積總體呈現(xiàn)陜油28>秦優(yōu)28>秦優(yōu)7號。3個品種的維管束面積和莖稈木質(zhì)素、纖維素含量變化趨勢相近。

2.4.2 播期和密度對不同油菜品種莖稈木質(zhì)素、纖維素含量的影響 同一播期, 密度增加, 莖稈纖維素含量和木質(zhì)素含量呈先增后降的趨勢。T1、T2及T3處理下, 3個品種纖維素和木質(zhì)素均在D2達到最大值, 在D1最小; 同一密度, 播期推遲, 莖稈木質(zhì)素和纖維素含量呈下降趨勢, 3個品種莖稈纖維素和木質(zhì)素含量都呈現(xiàn)終花期>角果期>成熟期>初花期的趨勢, 2年規(guī)律一致(圖6)。相同條件下, 4個時期下3個品種莖稈的纖維素和木質(zhì)素含量均表現(xiàn)為陜油28>秦優(yōu)28>秦優(yōu)7號。品種、播期及密度對各生育時期的莖稈木質(zhì)素、纖維素含量影響均達顯著水平(表4)。相關(guān)性分析表明, 莖稈木質(zhì)素、纖維素含量均與倒伏指數(shù)呈極顯著負相關(guān); 與莖稈抗折力呈極顯著正相關(guān)(表5)。

圖3 不同播期和密度下S28成熟期莖稈橫截面

a～c: 密度為D1時, 不同播期處理的莖稈橫截面; a: T1, b: T2, c: T3。d～f: 播期為T1時, 不同密度處理下的莖稈橫截面; d: D1, e: D2, f: D3。ph: 韌皮部; pi: 髓部; ve: 導(dǎo)管; xy: 木質(zhì)部?？s寫同圖1。

a–c: the cross section of the culm under different sowing dates when the density is D1. a: T1, b: T2, c: T3. d–f: the cross section of the culm under different densities when the sowing date is T1. d: D1, e: D2, f: D3. ph: phloem; pi: pith; ve: vessel; xy: xylem. Treatments are the same as those given in Table.

(圖4)

A: 密度為D1 (22.5萬株 hm–2)時播期對莖稈截面、維管束面積及其占比的影響; B: 播期為T1 (9月24日)時密度對莖稈截面、維管束面積及其占比的影響。縮寫同表1。不同小寫字母表示在0.05概率水平差異顯著。

A: the effects of sowing date on stem cross-section, vascular bundle area, and its proportions when the density is D1 (225,000 plants hm–2); B: the effect of density on the cross section of the stem, the area of vascular bundles, and its proportions when the sowing date is T1 (Sep. 24). Abbreviations are the same as those given in Table 1. Different lowercase letters indicate significant differences at the 0.05 probability level.

圖5 密度為D3 (67.5萬株hm-2)、播期為T3 (10月8日)處理下各品種成熟期莖稈橫切面圖

a, d: 秦優(yōu)7號; b, e: 秦優(yōu)28; c, f: 陜油28; ph: 韌皮部; pi: 髓部; ve: 導(dǎo)管; xy: 木質(zhì)部。

a, d: Qinyou 7; b, e: Qinyou 28; c, f: Shaanyou 28; ph: phloem; pi: pith; ve: vessel; xy: xylem.

3 討論

播期和種植密度是調(diào)控作物產(chǎn)量及抗倒伏能力的重要栽培措施, 二者可通過控制群體結(jié)構(gòu), 使植株光合速率、莖部結(jié)構(gòu)及干物質(zhì)積累與運輸?shù)? 最終使抗倒伏能力及籽粒產(chǎn)量等關(guān)鍵指標出現(xiàn)差異。倒伏是阻礙油菜高產(chǎn)的重要因素之一, 抗倒伏性取決于植株的株型、株高、植株的重心相關(guān), 并與植株的生理生化性狀、莖稈抗折力、壁厚及木質(zhì)素含量等相關(guān)[22-24]。前人的研究多集中于播期與種植密度對產(chǎn)量的影響上,或施氮量與種植密度對抗倒伏性的影響上, 而對于播期和種植密度對植株抗倒伏能力較少。本文研究了不同播期和種植密度條件下油菜產(chǎn)量及抗倒伏情況, 為遲播油菜選擇適宜的種植密度與播期提供了理論依據(jù)。

圖6 不同播期和密度對油菜莖稈主要成分的影響

FB、FF、SS和MS分別表示初花期、終花期、角果期、成熟期。*、**表示在0.05和0.01概率水平差異顯著?？s寫同表1。

FB, FF, SS, and MS represent initial blooming, final flowering, silique stage, and maturity stage, respectively. * and ** indicate significant difference at the 0.05 and 0.01 probability levels, respectively. Abbreviations are the same as those given in Table 1.

表4 不同時期油菜莖稈成分的方差分析

*、**表示在0.05和0.01概率水平顯著差異, NS表示差異不顯著。V×T、V×D、T×D和V×T×D分別表示因素間互作?？s寫同表1。

* and ** indicate significant difference at the 0.05 and 0.01 probability levels, respectively. NS: not significant difference; T: sowing date; V: variety; D: density. V×T, V×D, T×D, and V×T×D mean the interaction between factors, respectively. Abbreviations are the same as those given in Table 1.

表5 木質(zhì)素、纖維素含量與倒伏指數(shù)、莖稈抗折力的關(guān)系

**表示在0.01概率水平差異顯著。

**represents significant difference at the 0.01 probability level.

播期顯著影響油菜植株生長發(fā)育及品質(zhì)形成, 遲播條件下, 植株苗期營養(yǎng)生長不足, 冬前干物質(zhì)積累不足, 導(dǎo)致株高、產(chǎn)量構(gòu)成三因素顯著下降[25]。本試驗結(jié)果與前人研究結(jié)果相似, 相同密度下, 隨著播期的推遲, 3個品種單株角果數(shù)、每角粒數(shù)、株高、地上部干重等指標均呈下降趨勢, 實收產(chǎn)量也逐漸降低, 遲播油菜經(jīng)濟指標劣于適宜播期油菜。本試驗中T1、T2、T3處理分別在45萬株 hm–2、45.0萬株 hm–2、67.5萬株 hm–2密度下達到群體產(chǎn)量的最大值; 適宜播期(T1)下, 實收產(chǎn)量隨著密度的增加呈先增后降的趨勢, 遲播條件(T3)下, 實收產(chǎn)量隨著密度的增加而增加, 證明合理密植可改善油菜群體質(zhì)量、提高產(chǎn)量, 但植株過密, 個體生長受到抑制, 產(chǎn)量下降[5,26]。

品種是決定植株產(chǎn)量及抗倒伏能力的根本因素,同一作物不同品種間抗倒伏能力和耐遲播性均存在差異, 其中株高較低、莖稈硬度較高、株型緊湊、根系發(fā)達的品種抗倒性較好[27-29]。莖稈中纖維素與木質(zhì)素分別影響莖稈的任性與強度[30-31], 一般強抗倒伏品種纖維素與木質(zhì)素含量均大于弱抗倒伏品種[32]。本研究結(jié)果表明, 陜油28耐遲播性優(yōu)于其他品種, 秦優(yōu)28次之, 秦優(yōu)7號較差。相同處理下陜油28莖稈抗折力、纖維素與木質(zhì)素含量、莖稈維管束面積、維管束占比等指標均優(yōu)于秦優(yōu)28及秦優(yōu)7號, 陜油28抗倒伏性強于其他2個品種, 且陜油28的產(chǎn)量高于秦優(yōu)28及秦優(yōu)7號。因此, 選擇抗倒、耐密、耐遲播品種是遲播油菜高產(chǎn)抗倒的首要條件。

增加密度, 通過彌補單株產(chǎn)量不足進而提高群體產(chǎn)量, 是提高遲播油菜產(chǎn)量的重要措施, 但種植密度過大會導(dǎo)致個體莖稈發(fā)育不良, 抗折力弱, 增加倒伏風(fēng)險[3]。植株重量主要是由莖稈支撐的, 因此莖稈抗折力主要有莖稈特性決定。研究認為植株的抗倒伏性與株高成負相關(guān), 與莖粗、莖部維管束面積正相關(guān)[33]。董曉芳等研究表明, 油菜單位長度的莖稈抗折力隨種植密度的增加而減少[34], 同一品種, 種植密度越大, 倒伏越嚴重[35]; 但有研究報道, 適度增加密度倒伏指數(shù)減小, 倒伏減輕[36]。本研究中T1、T2播期下, 3個品種倒伏指數(shù)隨著種植密度的增加呈先降后增趨勢, 遲播條件下(T3), 適當增加種植密度, 油菜株高、根頸粗、地上干重與地下干重均顯著下降, 莖稈抗折力與倒伏指數(shù)均降低, 抗倒伏能力提高。本研究認為, 種植密度增加, 植株群體光合利用率下降, 個體間對水分、養(yǎng)分等競爭增強, 導(dǎo)致株高降低, 單株產(chǎn)量及每角粒數(shù)均下降, 植株冠層重量下降, 倒伏系數(shù)反而下降, 抗倒伏能力提高。盧昆麗等[13]研究表明, 木質(zhì)素含量高且含有較多及占比高的維管束具有較強的抗倒伏能力。Wang等[37]研究認為, 木質(zhì)素含量與莖稈抗折力呈正相關(guān),高木質(zhì)素含量可增加壁厚, 使莖稈的物理強度增加, 提高植株的抗倒伏能力。南銘等[38]認為木質(zhì)素是影響莖稈抗折力和機械強度的重要因素, 木質(zhì)素含量高的植株莖稈充實度高, 莖稈質(zhì)量優(yōu), 植株的抗倒伏能力較高。周海宇等[39]研究發(fā)現(xiàn), 強抗倒伏種質(zhì)具有較強的莖稈強度, 莖稈纖維素含量高, 維管束數(shù)目多。本試驗中, 適宜播期下, 木質(zhì)素、纖維素含量隨密度增加表現(xiàn)為先增后降趨勢, 維管束/莖稈橫截面積呈先增后降的趨勢, 高密度種植時, 莖稈因發(fā)育進程加快而基部變細, 維管束面積顯著下降, 導(dǎo)致單產(chǎn)下降, 但群體產(chǎn)量增強。因此, 合理密植可有效減少個體與群體間的沖突, 提高植株的產(chǎn)量及抗倒伏能力。遲播條件下, 莖稈中木質(zhì)素與纖維素含量減少, 單株產(chǎn)量下降, 但鮮重與株高降幅大于莖稈抗折力降幅, 倒伏指數(shù)降低, 抗倒伏能力增強; 此時合理增加密度, 可進一步加強抗倒伏能力, 植株產(chǎn)量與抗倒伏性協(xié)同提高, 達到以密補遲的效果。

4 結(jié)論

合理密植時, 油菜倒伏指數(shù)下降、抗倒伏能力增強, 油菜單株產(chǎn)量下降, 但群體產(chǎn)量增加。適宜播期條件(T1)下, 種植密度為45.0萬株 hm–2時最為適宜; 遲播條件下, 增加種植密度到67.5萬株 hm–2時最適。植株的形態(tài)學(xué)特性與莖稈生理特性影響莖稈的抗倒伏能力以及產(chǎn)量, 不同處理下莖稈中木質(zhì)素和纖維素含量高、維管束面積及占比大的植株, 可同時獲得較強的抗倒伏能力與較高的產(chǎn)量。密度與遲播對油菜的影響存在品種間差異, 在相同條件下, 強抗倒伏品種的產(chǎn)量優(yōu)于弱倒伏品種。遲播條件下, 同一種植密度, 陜油28的產(chǎn)量性狀(角果數(shù)、每角粒數(shù)、產(chǎn)量)均優(yōu)于秦優(yōu)28和秦優(yōu)7號, 最終群體產(chǎn)量也較高, 表明陜油28具有較好的耐密性及遲播適應(yīng)性。因此, 選擇抗倒伏能力強、耐密和耐遲播性好的品種以及增大種植密度是遲播條件下獲得高產(chǎn)的重要途徑。

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Effects of sowing date and density on lodging resistance and yield of different rapeseed cultivars

GONG Ruo-Lin, SONG Bo, YANG Zhi-Ye, LU Li-Jing, and DONG Jun-Gang*

College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China

To study the effects of late sowing and density on the lodging resistance and yield of rapeseed, and to provide the theoretical and technical support for the mechanized production of rapeseed, using three canola varieties (Shaanyou 28, Qinyou 28, and Qinyou 7) as the experimental materials, three sowing dates (T1: September 24, T2: October 1, and T3: October 8), and three densities (D1: 225,000 plants hm–2, D2: 450,000 plants hm–2, and D3: 675,000 plants hm–2) were set up to analyze the yield and constituent factors, the indexes related to lodging, the main components of the stem and the microstructure of the stem. The results showed that: (1) Under T1 and T2 treatments, with the increase of plant density, the yield of each plant of the three varieties decreased, the group yield increased first and then decreased, the lodging index decreased first and then increased, the vascular bundle and stem cross-sectional area decreased, the vascular bundle area/stem cross-sectional area, stem lignin, and cellulose content increased first and then decreased, the group yield was the largest at D2, while the lodging index was the smallest, and the yield and lodging resistance increased synergistically. Under the late sowing condition (T3), with the increase of density, the yield, lodging index, stem lignin, and cellulose content, above-ground fresh weight, vascular bundle area, stem cross-sectional area, and their ratios of the three cultivars decreased significantly, the group yield and lodging resistance increased, the lignin content was significantly positively correlated with the lodging resistance of stems, and the population yield and material resistance reached the maximum at D3. Compared with the normal sowing period (T1), the effective pods per plant, seeds per pod, yield per plant, population yield, and above-ground fresh weight the lodging index of each plant decreased significantly under the late sowing condition (T3), but the lodging resistance was enhanced. (2) Under the normal sowing period (T1), when the yield of the three variety groups was the highest, planting density was 450,000 plants hm–2. When the sowing date was delayed from T1 to T3, the yield of the three varieties was the highest at the density of 675,000 plants hm–2, among which Shaanyou 28 had the best density tolerance and late sowing resistance. In conclusion, under the late sowing condition, selecting dense and late sowing tolerant varieties and moderately increasing the density can compensate for the lack of yield, significantly increase the lignin and cellulose content of the stem, enhance the lodging resistance of rapeseed, effectively coordinate the contradiction between high yield and lodging, and achieve high yield and lodging resistance of late sowing rapeseed by compensating late with dense.

rapeseed; sowing date; planting density; yield; lodging resistance

10.3724/SP.J.1006.2023.24248

本研究由陜西省重點研發(fā)計劃項目(2022NY-155)資助。

This study was supported by the Key Research and Development Program Project of Shaanxi Province (2022NY-155).

董軍剛, E-mail: djg1101@aliyun.com

E-mail: gongrl_827@163.com

2022-11-07;

2023-02-21;

2023-02-28.

URL: https://kns.cnki.net/kcms/detail//11.1809.S.20230228.1035.004.html

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).