呂偉生,黃國強(qiáng),邵正英,曾勇軍,石慶華,潘曉華,魏賽金※
(1. 江西農(nóng)業(yè)大學(xué)生物科學(xué)與工程學(xué)院/雙季稻現(xiàn)代化生產(chǎn)協(xié)同創(chuàng)新中心/江西省作物生理生態(tài)與遺傳育種重點(diǎn)實(shí)驗(yàn)室/江西省農(nóng)業(yè)微生物資源開發(fā)與利用工程實(shí)驗(yàn)室,南昌 330045; 2.江西省紅壤研究所/國家紅壤改良工程技術(shù)研究中心/農(nóng)業(yè)部江西耕地保育科學(xué)觀測實(shí)驗(yàn)站,南昌 331717)
接種菌劑腐熟稻草育秧基質(zhì)提高機(jī)插稻秧苗素質(zhì)及產(chǎn)量
呂偉生1,2,黃國強(qiáng)1,邵正英1,曾勇軍1,石慶華1,潘曉華1,魏賽金1※
(1. 江西農(nóng)業(yè)大學(xué)生物科學(xué)與工程學(xué)院/雙季稻現(xiàn)代化生產(chǎn)協(xié)同創(chuàng)新中心/江西省作物生理生態(tài)與遺傳育種重點(diǎn)實(shí)驗(yàn)室/江西省農(nóng)業(yè)微生物資源開發(fā)與利用工程實(shí)驗(yàn)室,南昌 330045; 2.江西省紅壤研究所/國家紅壤改良工程技術(shù)研究中心/農(nóng)業(yè)部江西耕地保育科學(xué)觀測實(shí)驗(yàn)站,南昌 331717)
為探明稻草育秧基質(zhì)在機(jī)插稻生產(chǎn)中的應(yīng)用效果,該文以水稻土(CK)為對(duì)照,研究了接種自制腐稈菌劑的稻草基質(zhì)(T1)、不接種腐稈菌劑的稻草基質(zhì)(T2)2種基質(zhì)理化性狀及其對(duì)機(jī)插稻秧苗素質(zhì)、機(jī)插質(zhì)量及產(chǎn)量形成的影響。結(jié)果表明,T1、T2容重顯著低于CK,含水量、孔隙度(通氣孔隙度和持水孔隙度)和養(yǎng)分含量則顯著高于CK;接種腐稈菌劑改善了稻草育秧基質(zhì)的理化性狀,可降低基質(zhì)有機(jī)質(zhì)含量、提高速效養(yǎng)分濃度及減小碳氮比(C/N)。與T2和CK相比,T1培育出的秧苗綜合素質(zhì)較好、機(jī)插質(zhì)量高,有利于促進(jìn)大田分蘗早生快發(fā),同時(shí)增加了各時(shí)期葉面積指數(shù)、干物質(zhì)質(zhì)量及N、P、K吸收量,可形成較多的有效穗和充足的總穎花量,最終促進(jìn)水稻高產(chǎn)的形成。T1產(chǎn)量比CK提高了4.37%,增產(chǎn)效果顯著??梢?,接種腐稈菌劑的稻草基質(zhì)能滿足水稻秧苗正常生長,與當(dāng)前機(jī)插技術(shù)兼容性強(qiáng),有利于提高機(jī)插稻產(chǎn)量及稻草的資源化利用,是一種較為理想的機(jī)插稻育秧基質(zhì)。
基質(zhì);機(jī)械化;秸稈;機(jī)插稻;腐稈菌劑;理化性狀;秧苗素質(zhì);產(chǎn)量形成
水稻是中國的主要糧食作物,全國有近2/3的人口以稻米為主食,水稻生產(chǎn)在保障國家糧食安全方面占有極其重要的地位[1-3]。隨著經(jīng)濟(jì)的快速發(fā)展和農(nóng)村勞動(dòng)力的大量轉(zhuǎn)移,機(jī)械化已成為水稻生產(chǎn)發(fā)展的重要方向,但種植機(jī)械化仍是其中最薄弱環(huán)節(jié),雙季稻區(qū)種植機(jī)械化發(fā)展尤為緩慢[4]。“秧好一半禾,壯秧產(chǎn)量高”,足見育秧在水稻生產(chǎn)中的重要性。而機(jī)插稻育秧與傳統(tǒng)水稻育秧差異較大,育秧難特別是育秧基質(zhì)問題一直是制約機(jī)插稻發(fā)展的一個(gè)重要因素[5]。目前,旱地土育秧和本田泥漿育秧是中國南方稻區(qū)機(jī)插育秧的主要方式,但其用土(泥)量大、對(duì)土壤耕作層破壞嚴(yán)重、勞動(dòng)強(qiáng)度大等問題突出,不利于機(jī)插秧的可持續(xù)發(fā)展[6]。因此,充分利用有機(jī)廢棄物如食用菌菌渣[7-8]、谷殼[8-10]、草木灰[11]、泥炭[12]和有機(jī)肥[13-14]等原料,研發(fā)可全部或部分替代土(泥)的水稻育秧基質(zhì)成為當(dāng)前的研究熱點(diǎn)。中國農(nóng)業(yè)廢棄物資源十分豐富,每年僅作物秸稈產(chǎn)量就多達(dá)7億t,其中近1/3為水稻秸稈[15-16]。然而,因缺乏相應(yīng)的技術(shù)和設(shè)備,2/3以上的秸稈被廢棄或焚燒,造成嚴(yán)重的資源浪費(fèi)和環(huán)境污染[17]。合理利用秸稈開發(fā)有機(jī)基質(zhì),不僅能解決因廢棄或焚燒帶來的資源浪費(fèi)和環(huán)境污染問題,也可以在一定程度上緩解育秧取土(泥)難的問題[18-19]。目前秸稈作為有機(jī)基質(zhì)的研究和應(yīng)用主要集中在辣椒[20]、番茄[21-22]等蔬菜栽培上,而作為機(jī)插稻育秧基質(zhì)的研究還鮮有報(bào)道[23]。近年來,本研究團(tuán)隊(duì)篩選出能夠快速分解稻草的微生物,并研制成了復(fù)合腐稈菌劑[24],該菌劑可顯著提高稻草堆肥質(zhì)量[25]及稻草還田效果[26-28]。受此啟發(fā),本研究以稻草、水稻土及自行研制的復(fù)合腐稈菌劑為試驗(yàn)材料,按照一定比例混配成稻草育秧基質(zhì)[23],在大田條件下探究基質(zhì)對(duì)機(jī)插稻秧苗素質(zhì)、機(jī)插質(zhì)量及產(chǎn)量形成的影響,以期為稻草資源化利用與機(jī)插稻生產(chǎn)發(fā)展提供參考。
1.1 試驗(yàn)材料
復(fù)合腐稈菌劑由黑曲霉、韋氏芽孢桿菌、解淀粉芽孢桿菌、巨大芽孢桿菌、葡萄球菌、氧化木糖無色桿菌組成,其中黑曲霉孢子濃度為1.0×1010cfu/g,總細(xì)菌活菌數(shù)為1.5×1010cfu/g。稻草為江西農(nóng)業(yè)大學(xué)農(nóng)業(yè)科技園頭年晚季稻收割后風(fēng)干的稻草,用機(jī)械粉碎過0.85 mm篩后備用。水稻土取自江西農(nóng)業(yè)大學(xué)上高水稻試驗(yàn)基地稻田耕作層(0~20 cm),經(jīng)風(fēng)干、磨碎并過5 mm篩后備用。供試水稻品種為三系雜交晚秈稻H優(yōu)518(國審稻2011020,被農(nóng)業(yè)部確認(rèn)為2013年全國12個(gè)超級(jí)稻示范推廣品種之一),該品種豐產(chǎn)性好、米質(zhì)優(yōu)且生育期適宜,是江西、湖南等雙季稻區(qū)晚稻機(jī)插的主推品種。
1.2 試驗(yàn)設(shè)計(jì)
稻草腐熟于2015年6月在江西農(nóng)業(yè)大學(xué)江西省農(nóng)業(yè)微生物資源開發(fā)與利用工程實(shí)驗(yàn)室進(jìn)行。腐熟試驗(yàn)設(shè)2個(gè)處理,處理1接種質(zhì)量分?jǐn)?shù)為8%的腐稈菌劑,處理2為不接種菌劑。根據(jù)微生物的發(fā)酵原理,接種質(zhì)量分?jǐn)?shù)控制在1%~10%均是可行的,前期室內(nèi)試驗(yàn)接種量為5%[25],為了保證菌劑在復(fù)雜的大田環(huán)境仍具有較高活性但又不與水稻爭奪過多的養(yǎng)分,故接種量設(shè)為8%。具體方法為:將稻草粉加水調(diào)至含水率60%~65%(處理1加水前即接種腐稈菌劑),添加質(zhì)量分?jǐn)?shù)1.0%的尿素,混合均勻后置于塑料桶內(nèi)堆漚發(fā)酵,3 d后進(jìn)行翻堆,并向堆體澆水,保證含水率為60%~65%,之后每3 d翻堆一次,以保證好氧條件,14 d后即得腐熟稻草。在稻草堆置發(fā)酵期間,室溫控制在25~35 ℃,堆體溫度控制在35~60 ℃[29]。
基質(zhì)育秧及大田機(jī)插試驗(yàn)于2015年7-10月在江西農(nóng)業(yè)大學(xué)上高水稻試驗(yàn)基地進(jìn)行。7月2日進(jìn)行基質(zhì)育秧試驗(yàn),設(shè)置3種處理﹕接種8%菌劑腐熟稻草﹕水稻土體積比為2﹕1(T1)、不接種菌劑腐熟稻草﹕水稻土體積比為2﹕1(T2)、水稻土(CK)。水稻播種前用100 mg/kg烯效唑(質(zhì)量分?jǐn)?shù)5%的可濕性粉劑)溶液浸種24 h,35℃催芽24 h。采用毯狀塑料硬質(zhì)秧盤(秧盤內(nèi)部長×寬×高為58 cm× 21.5 cm×2.8 cm)進(jìn)行流水線播種,盤內(nèi)基質(zhì)厚度2.6 cm,落谷密度2粒/cm2。秧盤置于秧田采用半旱育秧方式進(jìn)行秧苗管理。
7月21日進(jìn)行大田機(jī)插試驗(yàn),采用隨機(jī)區(qū)組設(shè)計(jì),每個(gè)處理設(shè)置3次重復(fù),每次重復(fù)對(duì)應(yīng)的小區(qū)面積72 m2(4 m×18 m)。采用井關(guān)牌乘坐式高速窄行插秧機(jī)栽插,栽插行株距25 cm×14 cm,取秧面積1.8 cm2,機(jī)插深度約2 cm。氮(N)、磷(P2O5)、鉀(K2O)施用量分別為180、90、165 kg/hm2,其中磷全作基肥,氮和鉀按基肥﹕分蘗肥﹕穗肥=5﹕2﹕3施用,分蘗肥與穗肥分別在機(jī)插后7 d和倒2葉抽出期施用。水分管理及其他大田栽培措施均按高產(chǎn)技術(shù)規(guī)程進(jìn)行。
1.3 指標(biāo)與方法
1.3.1 基質(zhì)理化性質(zhì)
基質(zhì)容重、孔隙度(通氣孔隙度、持水孔隙度)及含水量等物理性質(zhì)指標(biāo)采用常規(guī)方法測定[30];基質(zhì)pH、有機(jī)質(zhì)、全氮、堿解氮、速效磷和速效鉀含量等化學(xué)性質(zhì)指標(biāo)參也照常規(guī)方法測定[31]。
1.3.2 水稻秧苗素質(zhì)
移栽前1 d,每個(gè)處理選取3個(gè)10 cm×10 cm的秧塊,計(jì)數(shù)秧苗高度大于平均苗高1/2的秧苗數(shù),除以種子總數(shù)即為成苗率。結(jié)合成苗率測定,每個(gè)秧塊選取30株成苗的秧苗,分別記錄葉齡、測定苗高、莖基寬、根長及根數(shù)(0.5 cm以上的不定根),同時(shí)用手持便攜式葉綠素儀SPAD-520測定秧苗倒數(shù)第1片全展葉的相對(duì)葉綠素含量SPAD(soil and plant analyzer development, SPAD)值。最后將根和莖葉分開,在干燥箱內(nèi)105 ℃殺青15 min,再于80 ℃烘至恒質(zhì)量,冷卻至室溫后稱質(zhì)量。
1.3.3 秧苗機(jī)插質(zhì)量及田間發(fā)根力
參照《水稻插秧機(jī)試驗(yàn)方法》(GB 6243-2003)[32],栽后當(dāng)天每個(gè)小區(qū)選取中部的一個(gè)工作帶內(nèi)(共8行,每行15穴)的120穴為一調(diào)查點(diǎn),調(diào)查每穴苗數(shù)、傷秧率、漏蔸率、漂苗率和翻倒率。移栽后7 d,各處理再選取3個(gè)調(diào)查點(diǎn),每個(gè)調(diào)查點(diǎn)選取長勢均勻的10穴秧苗,計(jì)算每株的新生根數(shù)(0.5 cm以上的不定根),以表示秧苗的田間發(fā)根力。
1.3.4 水稻大田生長特性
1)莖蘗動(dòng)態(tài)。機(jī)插當(dāng)天開始調(diào)查,每個(gè)小區(qū)定苗10穴,每4 d調(diào)查一次莖蘗動(dòng)態(tài),直到齊穗期。
2)干物質(zhì)質(zhì)量及葉面積指數(shù)。于幼穗分化III期(二次枝梗分化期)、齊穗期、成熟期,每個(gè)小區(qū)調(diào)查50穴的莖蘗數(shù),按5點(diǎn)取樣法選取代表性的植株5穴,將莖鞘、葉、穗分開包扎,在干燥箱內(nèi)105 ℃殺青20 min,再于80 ℃烘至恒質(zhì)量,冷卻至室溫后稱質(zhì)量;同時(shí)按小葉干質(zhì)量法測算葉面積指數(shù)。
3)N、P、K養(yǎng)分吸收量。將成熟期干物質(zhì)樣品粉碎,過0.15 mm篩,N用FOSS—2300型全自動(dòng)定N儀測定,P用釩鉬黃比色法測定,K用火焰光度計(jì)測定[31]。
1.3.5 產(chǎn)量及產(chǎn)量構(gòu)成
成熟期取樣考種,每個(gè)小區(qū)按平均有效穗數(shù)選5株考查總粒數(shù)、空粒數(shù)、千粒質(zhì)量,同時(shí)每個(gè)小區(qū)中心實(shí)割250穴,脫粒、曬干、風(fēng)選后稱質(zhì)量,最后計(jì)算實(shí)際產(chǎn)量。
1.4 相關(guān)指標(biāo)計(jì)算
1.5 數(shù)據(jù)統(tǒng)計(jì)分析
運(yùn)用Excel 2007和DPS 7.05進(jìn)行數(shù)據(jù)分析和圖表繪制。
2.1 基質(zhì)理化特性
2.1.1 基質(zhì)物理性質(zhì)
基質(zhì)物理性質(zhì)決定了其持水性能、通氣狀況,對(duì)養(yǎng)分轉(zhuǎn)化能力也具有重要影響。由表1可知,不同育秧基質(zhì)的物理性質(zhì)存在一定差異。與純水稻土(CK)相比,添加稻草基質(zhì)處理(T1、T2)可顯著降低容重,T1、T2容重分別比CK低58.65%、63.46%;同時(shí)顯著提高含水率和孔隙度(通氣孔隙度和持水孔隙度)。接種復(fù)合菌劑腐解稻草基質(zhì)(T1)與不接種復(fù)合菌劑腐解稻草基質(zhì)(T2)相比,各項(xiàng)物理性狀指標(biāo)總體表現(xiàn)為T1、T2二者差異未達(dá)顯著水平。
表1 不同育秧基質(zhì)的物理性質(zhì)Table 1 Physical properties of different seedling substrates
2.1.2 基質(zhì)化學(xué)性質(zhì)
從表2可以看出,不同育秧基質(zhì)的化學(xué)性質(zhì)也存在較大的差異。3種基質(zhì)pH值在5.5~6.5之間,其中T1、T2顯著大于CK,但均滿足水稻秧苗適宜生長的弱酸環(huán)境[33-34]。有機(jī)質(zhì)含量與基質(zhì)肥力密切相關(guān),對(duì)秧苗生長具有一定促進(jìn)作用。T1、T2有機(jī)質(zhì)含量顯著高于CK,分別是CK的12.12和12.89倍?;|(zhì)全氮、堿解氮、速效磷、速效鉀等養(yǎng)分含量按T1、T2、CK的順序依次遞減,T1、T2顯著高于CK,全氮、速效磷含量T1與T2差異顯著。碳氮比(C/N)是反應(yīng)基質(zhì)穩(wěn)定性能的一項(xiàng)重要指標(biāo),稻草基質(zhì)C/N較高,T1、T2顯著大于CK,T2也顯著大于T1。
表2 不同育秧基質(zhì)的化學(xué)性質(zhì)Table 2 Chemical properties of different seedling substrates
2.2 水稻秧苗素質(zhì)
受基質(zhì)理化性狀的影響,不同育秧基質(zhì)培育出的秧苗綜合素質(zhì)有一定差異(表3)。除充實(shí)度外,秧苗素質(zhì)其余指標(biāo)均表現(xiàn)為按T1、T2、CK的順序逐漸遞減,T1顯著大于CK,其中壯秧指數(shù)增幅達(dá)8.57%;根長、根數(shù)、SPAD值以及根干質(zhì)量T1、T2之間差異達(dá)顯著水平。可見,稻草基質(zhì)適宜秧苗生長,可顯著提高秧苗素質(zhì),接種腐稈菌劑腐解的稻草基質(zhì)則更有利于秧苗地下部的生長,同時(shí)能較好地維持根冠之間的協(xié)調(diào)性,從而促進(jìn)地上部健康生長。
表3 不同育秧基質(zhì)對(duì)秧苗素質(zhì)的影響Table 3 Effects of different seedling substrates on seedling quality
2.3 秧苗機(jī)插質(zhì)量
水稻大田機(jī)插質(zhì)量受秧苗素質(zhì)、根系盤結(jié)力及秧田成苗率的綜合影響,并通過基本苗數(shù)影響群體發(fā)育。表4顯示,成苗率各處理間差異不顯著。漏蔸率則表現(xiàn)為T1 表4 不同育秧基質(zhì)對(duì)機(jī)插質(zhì)量的影響Table 4 Effects of different seedling substrates on mechanical transplanting quantity 2.4 水稻大田生長特性 2.4.1 莖蘗動(dòng)態(tài) 水稻莖蘗動(dòng)態(tài)是群體生長的直觀表現(xiàn),也是影響產(chǎn)量形成的重要因素。由圖1可以看出,各時(shí)期莖蘗數(shù)均表現(xiàn)為T1>T2>CK。機(jī)插后8 d內(nèi),T1、T2莖蘗數(shù)變化明顯,分別增加了137.02%和131.29%,而CK僅增加了112.49%。各處理在機(jī)插20 d后分蘗增長速率開始降低,并于機(jī)插后28~32 d左右出現(xiàn)分蘗最高峰。之后無效分蘗陸續(xù)死亡,莖蘗數(shù)不斷降低,至機(jī)插后56~60 d莖蘗數(shù)基本穩(wěn)定。經(jīng)定點(diǎn)調(diào)查,得到最終成穗數(shù)T1(371.45×104/hm2)高于T2(362.90×104/hm2)和CK(350.50×104/hm2)。成穗率(成穗數(shù)與高峰苗數(shù)的百分比)依次為T1(55.78%)>T2(55.19%)>CK(53.98%),其中T1比CK高3.33%,但二者無顯著差異??傮w來看,接種腐稈菌劑的稻草基質(zhì)育秧處理能促進(jìn)大田分蘗早生快發(fā),提高分蘗成穗率并獲取較多的有效穗數(shù)。 圖1 不同育秧基質(zhì)對(duì)莖蘗動(dòng)態(tài)的影響Fig.1 Effects of different seedling substrates on dynamics of tiller 2.4.2 光合生產(chǎn) 葉片是植物進(jìn)行光合生產(chǎn)的重要器官,各生育時(shí)期葉面積的大小對(duì)水稻群體結(jié)構(gòu)及產(chǎn)量形成具有重要影響。從圖2a可以看出,各生育時(shí)期葉面積指數(shù)(LAI)均表現(xiàn)為T1>T2>CK,各處理在分化III期差異不顯著;齊穗期至成熟期(灌漿結(jié)實(shí)期)差異增大,齊穗期T1比CK高9.40%,成熟期T1比 CK高25.09%,T1與CK之間存在顯著差異。T1 的LAI在齊穗期達(dá)6.5以上,并在整個(gè)灌漿結(jié)實(shí)期維持較高的水平。 各處理地上部干物質(zhì)質(zhì)量變化與LAI規(guī)律一致(圖2b),各生育時(shí)期也均表現(xiàn)為T1>T2>CK,分化III期各處理無顯著差異;齊穗期T1顯著高于CK,增幅達(dá)6.86%;至成熟期T1顯著高于T2和CK,增幅分別為3.91%、6.97%。由此可見,稻草基質(zhì)特別是接種腐稈菌劑的稻草基質(zhì)更有利于促進(jìn)全生育期尤其是中后期光合生產(chǎn)。 2.4.3 養(yǎng)分吸收 水稻成熟期N、P、K等養(yǎng)分吸收的分析如圖3所示,各養(yǎng)分吸收量均表現(xiàn)為按T1、T2、CK的順序依次遞減,其中T1顯著高于CK,這與總干物質(zhì)積累的變化趨勢一致。與CK相比,T1的N吸收量增加了6.83%,P吸收量增加了11.80%,K吸收量增加了6.30%。上述表明,稻草基質(zhì)尤其是接種腐稈菌劑的稻草基質(zhì)使水稻養(yǎng)分吸收優(yōu)勢明顯增強(qiáng)。 圖2 不同育秧基質(zhì)對(duì)不同生育期水稻葉面積指數(shù)及干物質(zhì)質(zhì)量的影響Fig.2 Effects of different seedling substrates on LAI and dry matter production of rice in different growth stage 圖3 不同育秧基質(zhì)對(duì)養(yǎng)分吸收的影響Fig.3 Effects of different seedling substrates on nutrient absorption 2.5 產(chǎn)量及產(chǎn)量構(gòu)成 由表5可知,水稻最終產(chǎn)量為T1>T2>CK,與CK相比,T1能顯著提高產(chǎn)量。其中,T1產(chǎn)量較CK提高4.37%。再從產(chǎn)量構(gòu)成上看,有效穗數(shù)和總穎花量均表現(xiàn)為T1>T2>CK,T1與CK差異顯著,這與產(chǎn)量變化規(guī)律一致。其中T1有效穗數(shù)比CK高4.30%,總穎花量T1比CK高4.89%;而每穗粒數(shù)、結(jié)實(shí)率及千粒質(zhì)量在各處理間差異不顯著。 由此表明,本試驗(yàn)條件下機(jī)插晚稻產(chǎn)量的增加主要通過提高有效穗數(shù)來實(shí)現(xiàn)。增加有效穗數(shù),并保持較大的穗型(較多的每穗粒數(shù))以形成較多的總穎花量,同時(shí)保證較高的結(jié)實(shí)率及千粒質(zhì)量,是添加菌劑腐熟稻草基質(zhì)育秧取得高產(chǎn)的重要原因。 3.1 稻草基質(zhì)對(duì)秧苗素質(zhì)的影響 基質(zhì)作為秧苗生長介質(zhì),除具備固持、供水、供肥和通氣等功能,還要求所培育的秧苗整齊度高、盤根性好、根冠比協(xié)調(diào),并能適應(yīng)機(jī)械化播種和流水線作業(yè),因而實(shí)際生產(chǎn)對(duì)其綜合性能有更高要求[5]?;|(zhì)的理化性狀如容重、持水性、孔隙度、pH值及養(yǎng)分含量等均與秧苗素質(zhì)密切相關(guān),并影響到機(jī)插質(zhì)量和最終產(chǎn)量[33]。研究表明,適宜作物生長的基質(zhì)容重為0.1~0.8 g/cm3,總孔隙度為54%~96%;其中適宜水稻秧苗生長的pH值為5.4~7.0,C/N小于30,養(yǎng)分含量適中[34]。魯耀雄等[13-14,33,35]采用基質(zhì)育秧,發(fā)現(xiàn)基質(zhì)養(yǎng)分含量、持水性、保水抗旱性等均優(yōu)于傳統(tǒng)營養(yǎng)土,因此秧苗的苗高、莖基寬、莖葉干質(zhì)量、根長、根數(shù)、根干質(zhì)量、根系活力等指標(biāo)相比營養(yǎng)土也均有顯著優(yōu)勢。本試驗(yàn)中稻草基質(zhì)物理性狀適宜,養(yǎng)分含量高,大部分理化性狀都處于較適宜秧苗生長的范圍,能適應(yīng)機(jī)械播種作業(yè),其中接種復(fù)合菌劑腐解稻草還在一定程度上改善了稻草基質(zhì)性能,所培育秧苗地上部與地下部生長特征及綜合素質(zhì)總體優(yōu)于對(duì)照。相比于對(duì)照,稻草基質(zhì)具有更小的容重、更好的通氣狀況和更強(qiáng)的持水性能,有利于種子出苗和根系生長,能育出均勻健壯的秧苗,同時(shí)也可有效減輕育秧及機(jī)插過程中的工作強(qiáng)度,提高育秧和插秧的效率。其中主要原因是,稻草質(zhì)地輕盈,且富含有機(jī)質(zhì)和氮、磷、鉀等速效養(yǎng)分[36],堆漚發(fā)酵將不穩(wěn)定的大分子有機(jī)物降解為速效養(yǎng)分和穩(wěn)定的腐殖質(zhì)[37],接種腐稈菌劑則進(jìn)一步加快了腐解速度、提高了堆漚質(zhì)量[25,38]。而就稻草基質(zhì)而言,腐稈菌劑主要通過改善基質(zhì)化學(xué)性狀來提高秧苗素質(zhì),如降低有機(jī)質(zhì)含量、提高速效N、P養(yǎng)分濃度及減小C/N等,而對(duì)基質(zhì)的物理性狀影響較??;同時(shí)也可能是改善了基質(zhì)生物性狀,如微生物的種類、數(shù)量及相關(guān)酶活性等[25]。 3.2 稻草基質(zhì)對(duì)機(jī)插質(zhì)量的影響 較高質(zhì)量的機(jī)插秧是農(nóng)機(jī)與農(nóng)藝密切配套的結(jié)果。機(jī)插稻秧苗不僅要嚴(yán)格符合插秧機(jī)作業(yè)質(zhì)量的標(biāo)準(zhǔn),同時(shí)還要有利于水稻高產(chǎn)優(yōu)質(zhì)的形成,因此秧苗素質(zhì)對(duì)機(jī)插質(zhì)量及產(chǎn)量形成均具有十分重要的影響。在當(dāng)前的技術(shù)條件下,機(jī)插稻的壯秧標(biāo)準(zhǔn)為:葉齡2.5~4.0,苗高12~20 cm,莖基寬2 mm以上,葉色翠綠,根系盤結(jié)成毯,群體成苗率高,栽后早發(fā)性好[6]。本試驗(yàn)中,相比于傳統(tǒng)水稻育秧土,稻草基質(zhì)培育出的秧苗素質(zhì)較高,相關(guān)指標(biāo)基本達(dá)到機(jī)插壯秧標(biāo)準(zhǔn)。秧田成苗率與基質(zhì)的通氣性狀、持水性能及養(yǎng)分含量密切相關(guān),成苗率也決定了秧盤中秧苗的數(shù)量和質(zhì)量,并直接影響機(jī)插質(zhì)量(特別是漏蔸率與基本苗數(shù))[33]。稻草基質(zhì)主要由腐熟的水稻秸稈組成,質(zhì)地疏松、通氣狀況良好、持水能力較強(qiáng)、養(yǎng)分含量較高,所育秧苗根系發(fā)達(dá)、地上部健壯、根冠比協(xié)調(diào)、成苗率較高,能更好地適應(yīng)大田機(jī)械化栽插作業(yè),因此最終保證較高的機(jī)插質(zhì)量(如較低的漏蔸率及較強(qiáng)的大田發(fā)根力)。其中,稻草基質(zhì)處理的機(jī)插質(zhì)量總體優(yōu)于傳統(tǒng)水稻土,接種腐稈菌劑的稻草基質(zhì)與機(jī)插技術(shù)兼容性強(qiáng),更有利于提高機(jī)插質(zhì)量。與大面積生產(chǎn)相比,本試驗(yàn)中各處理機(jī)插質(zhì)量均表現(xiàn)較好,這可能與本試驗(yàn)采用了播種機(jī)勻播及高性能插秧機(jī)栽插等最新農(nóng)機(jī)技術(shù)有關(guān)。 3.3 稻草基質(zhì)對(duì)產(chǎn)量形成的影響 前人關(guān)于機(jī)插稻育秧基質(zhì)的研究主要側(cè)重于不同基質(zhì)對(duì)秧苗素質(zhì)及最終產(chǎn)量的影響,而對(duì)產(chǎn)量形成的影響研究較少。一般而言,秧苗素質(zhì)弱,則機(jī)插質(zhì)量差,栽插后秧苗返青活棵慢,分蘗缺位較多,最終穗數(shù)偏少,穗型偏小,產(chǎn)量下降[33,39-40],同時(shí)也往往會(huì)造成齊穗期推遲,生育期延長[33,41]。相關(guān)研究表明,采用基質(zhì)育秧可提高秧苗素質(zhì),秧苗移栽后返青快,分蘗力強(qiáng),可促進(jìn)穗數(shù)和大穗的形成,從而實(shí)現(xiàn)增產(chǎn)[33,40,42]。本研究發(fā)現(xiàn),相比傳統(tǒng)的水稻土,稻草基質(zhì)尤其是接種腐稈菌劑的稻草基質(zhì)培育的秧苗地上部與根系生長特征及綜合素質(zhì)較優(yōu),機(jī)插后大田發(fā)根力強(qiáng),分蘗早生快發(fā)、成穗率較高,增加了各時(shí)期葉面積指數(shù)、光合產(chǎn)量及植株養(yǎng)分積累,可形成較多的有效穗和總穎花量,構(gòu)建高質(zhì)量群體,從而促進(jìn)水稻高產(chǎn)的形成。但也有研究表明,基質(zhì)育秧并不一定就能達(dá)到顯著增產(chǎn)的效果,如王顯等[43]研究發(fā)現(xiàn)多數(shù)基質(zhì)產(chǎn)量略低于傳統(tǒng)營養(yǎng)土,這可能是基質(zhì)配方不同所致。在本試驗(yàn)中,機(jī)插晚稻總穎花量與產(chǎn)量呈極顯著正相關(guān)(r=0.925 1**),總穎花量的增加主要依靠有效穗數(shù)的提高(r=0.926 6**),而結(jié)實(shí)率及千粒質(zhì)量與產(chǎn)量相關(guān)不顯著,這與張結(jié)剛等[44]研究結(jié)果基本一致。這也進(jìn)一步表明,提高有效穗數(shù)以獲取較多的總穎花量,同時(shí)維持較高的結(jié)實(shí)率和千粒質(zhì)量,仍是當(dāng)前雙季機(jī)插稻實(shí)現(xiàn)高產(chǎn)的主攻方向。因此,雙季機(jī)插稻更應(yīng)重視育秧基質(zhì)的使用,在培育標(biāo)準(zhǔn)壯秧的基礎(chǔ)上保證較高的機(jī)插質(zhì)量,同時(shí)優(yōu)化大田肥水管理,從而塑造穗粒充足的高質(zhì)量群體。 江西省是中國雙季稻優(yōu)勢種植區(qū),該區(qū)域年際間及早、晚稻季別間氣候波動(dòng)較大,而本試驗(yàn)僅研究了1季晚稻,難以全面反映稻草基質(zhì)的應(yīng)用效果,因此仍需開展多年份多季別的大田試驗(yàn),以更充實(shí)的試驗(yàn)數(shù)據(jù)來支撐本文結(jié)論。此外,盡管本試驗(yàn)中稻草基質(zhì)育秧效果優(yōu)于傳統(tǒng)水稻土,但綜合壯秧、培肥、抗病、高產(chǎn)等多功能基質(zhì)產(chǎn)品的生產(chǎn)工藝技術(shù)還有待于進(jìn)一步深入研究。 1)稻草基質(zhì)容重顯著低于傳統(tǒng)育秧土,含水量、孔隙度和養(yǎng)分含量則顯著高于傳統(tǒng)育秧土;接種腐稈菌劑改善了稻草育秧基質(zhì)的理化性狀,主要表現(xiàn)為提高基質(zhì)速效N、P養(yǎng)分濃度及減小C/N。 2)與傳統(tǒng)育秧土和不接種腐稈菌劑的稻草基質(zhì)相比,接種腐稈菌劑的稻草育秧基質(zhì)育出的秧苗綜合素質(zhì)較好、機(jī)插質(zhì)量高,有利于分蘗早生快發(fā);特別是相比傳統(tǒng)育秧土,接種腐稈菌劑的稻草育秧基質(zhì)顯著增加了齊穗期和成熟期的葉面積指數(shù)(增幅9.40%、25.09%)、干物質(zhì)質(zhì)量(增幅6.86%、6.97%)及植株N、P、K吸收量(增幅6.83%、11.80%、6.30%),可形成較多的有效穗(增幅4.30%)和充足的總穎花量(增幅4.89%),從而促進(jìn)高產(chǎn)(增產(chǎn)4.37%)。 3)將接種腐稈菌劑腐熟的稻草作為水稻機(jī)插育秧基質(zhì)的主要成分,滿足水稻秧苗正常生長,與當(dāng)前機(jī)插技術(shù)兼容性強(qiáng),有利于提高機(jī)插稻產(chǎn)量及稻草的資源化利用。 [1] Peng S B, Buresh R J, Huang J L, et al. 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(in Chinese with English abstract) Straw substrate with decomposition agent improving seedling quality and yield of machine-transplanted rice Lü Weisheng1,2, Huang Guoqiang1, Shao Zhengying1, Zeng Yongjun1, Shi Qinghua1, Pan Xiaohua1, Wei Saijin1※ Machine-transplanted rice had many advantages, such as maintaining high efficiency, saving cost, freeing labor, and stabilizing yield, so the area of machine-transplanted rice becomes larger and larger in China in recent years. With the expansion area of machine-transplanted rice, the demand for high quality of rice seedling becomes more and more important. However, traditional seedling raising method such as using paddy soil as the seedbed substrate is difficult to meet the growing demand of machine-transplanted rice seedling. It is predicted that more new seedbed substrates for rice seedlings such as mixed substrate and light soilless substrate will replace nutrient soil for raising rice seedling. Organic waste substituted as raising substrate, such as straw seedling substrate is widely used on vegetable production. In recent years, we have developed an organic compound decomposing agent, which can decompose the straw rapidly. And also, straw composting plus straw decomposition agent can improve the quality of compost. Inspired by these, we need to study the effect of straw decomposition agent applied to straw substrate seedbed and machine-transplanted rice production. Field experiments were conducted with hybrid rice cultivar Hyou518 at the experimental farm of Jiangxi Agricultural University, Jiangxi Province, China in late-growing season in 2015. And the experiments were conducted under the condition of mechanical seedling and transplanting with high-yield agronomy technology during the whole growth period of late rice, and with three replicates for each treatment. In the field experiments, three types of rice seedbed substrates: straw substrate plus straw decomposition agent (T1), straw substrate without straw decomposition agent (T2) and paddy soil (CK) were used to compare their physical and chemical properties. The effects of different seedbed substrates on seedling and transplanting quality and yield formation of machine-transplanted rice were also analyzed. The results showed that, bulk density of T1 and T2 were 58.65% and 63.46% lower (P<0.05) than CK, while the porosity (aeration porosity and water-holding porosity) and water content were significantly higher (P<0.05) than CK (except water-holding porosity of T2). Inoculating straw decomposition agent to straw seedbed substrate was beneficial to improve the physical and chemical properties of straw seedbed substrate, reduce organic content, improve available nutrient concentrations, and decrease C/N ratio. Compared with T2 and CK, T1 had better seedling and transplanting quality, earlier and faster growth of tillering at early growth stage, and higher LAI, dry matter production and nutrient (N, P, K) absorption. Moreover, T1 had more panicles and total spikelet, and higher grain yield. The grain yield of T1 was 2.25% and 4.37% higher than that of T2 and CK, respectively. The results suggest that straw seedling substrate plus straw decomposition agent fulfilled the condition of seedling growth, and the seedlings were more suitable for current mechanized transplanting technology than paddy soil. In summary, the straw seedbed substrate added with the decomposition agent is a suitable seedling substrate of machine-transplanted rice because of its superiority on improving the grain yield and the utilization of straw resources. The production process technology of multifunctional substrate that produces strong seedling, improves soil fertility and disease resistance, and produces high yield still needs to be further studied, even though straw seedbed substrate from this study is more suitable for current mechanized transplanting technology than traditional seedling raising pattern. In addition, it is noted that this study just included one year experimental data in late rice field. Future studies on the validation and perfection of multiple years and sites are needed in the future. substrates; mechanization; straw; machine-transplanted rice; straw decomposition agent; physical and chemical properties; seedling quality; yield formation 10.11975/j.issn.1002-6819.2017.11.025 S511; S233.71 A 1002-6819(2017)-11-0195-08 呂偉生,黃國強(qiáng),邵正英,曾勇軍,石慶華,潘曉華,魏賽金. 接種菌劑腐熟稻草育秧基質(zhì)提高機(jī)插稻秧苗素質(zhì)及產(chǎn)量[J]. 農(nóng)業(yè)工程學(xué)報(bào),2017,33(11):195-202. 10.11975/j.issn.1002-6819.2017.11.025 http://www.tcsae.org Lü Weisheng, Huang Guoqiang, Shao Zhengying, Zeng Yongjun, Shi Qinghua, Pan Xiaohua, Wei Saijin. Straw substrate with decomposition agent improving seedling quality and yield of machine-transplanted rice[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2017, 33(11): 195-202. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2017.11.025 http://www.tcsae.org 2016-10-09 2017-04-20 國家科技支撐計(jì)劃(2011BAD16B04、2012BAD04B11、2013BAD07B1202);江西省科技計(jì)劃項(xiàng)目(20144BBF60003);公益性行業(yè)(農(nóng)業(yè))科研專項(xiàng)(201303102) 呂偉生,男,江西信豐人,博士,助理研究員,主要從事水稻機(jī)械化高產(chǎn)栽培技術(shù)研究。南昌 江西省紅壤研究所,331717。 Email:Lvweisheng2008@163.com ※通信作者:魏賽金,女,江西南昌人,博士,教授,主要從事農(nóng)業(yè)生物技術(shù)研究。南昌 江西農(nóng)業(yè)大學(xué)生物科學(xué)與工程學(xué)院,330045。 Email:weisaijin@126.com3 討 論
4 結(jié) 論
(1. College of Biology Science and Engineering, Jiangxi Agricultural University/Collaborative Innovation Center for the Modernization Production of Double Cropping Rice/Jiangxi Key Laboratory of Crop Physiology, Ecology and Genetic Breeding/ Jiangxi Agricultural Microbial Resource Development and Utilization Engineering Lab, Nanchang 330045, China; 2. Jiangxi Institute of Red Soil / National Engineering and Technology Research Center for Red Soil Improvement/Scientific Observational and Experimental Station of Arable Land Conservation in Jiangxi, Ministry of Agriculture, Nanchang 331717, China)