硫化氫中毒:根係發黑,並有臭雞蛋氣味,白根少而細弱;基部老葉呈現黃褐色,葉尖枯黃,隨後老葉枯死,上部僅存一二片綠色新葉。
有機酸中毒:daozhugenxiweisuo,henshaoshengfaxingen,zhizhugenxibiaopifashengtuoluo,yesexianhuang,huochanshengweisuoxianxiang,yanzhongshixiabuyepiankuhuangersi。fanfashengzhongduxingfahuangdedaotianyinglijipaishuishaitian,gaishanturangdetongtouxing,zengyangpaidu。bingjiehezhonggeng,zaishaitianfushuishishiyongdan、磷、鉀速效肥料,以改善稻株的營養條件。在有機酸過多的稻田,可施用土壤改良劑,如生石灰等以中和酸性,消除有害物質。
缺素發黃
缺氧發黃:主要是從老葉片的尖端開始發黃,後逐漸由莖葉延至心葉,最後發展至全株成黃綠色。嚴重時由葉尖、葉緣向內枯黃,秧苗生長緩慢,遠看秧苗一片黃色。出現這種症狀狀應及時追施尿素、碳酸氫銨等速效氮肥。
缺鉀發黃:主要發生在大量施用氮、磷的高產稻田。初期表現為生長緩慢、zhuxingaixiao,fennieshao,yepiantingzhi,dingduanyepiancongshengzhuang。xinyeanlvsewuguangze,xiabulaoyejianduanshouxianfahuang,youdaxiaobudengdechihesebandian,houyanyemaixiangjibukuozhan,zuihouzhengzhuyepianbianchengchihese,youdeshenzhikusi,yuankanxiangbeihuoshaojiaoyiyang,zheshidianxingdequejiachikubing。chuxianzhezhongzhengzhuangyaolijipaishui,caiyongjianxiguangai,jishizhuishijiafei。
缺鋅發黃:主要發生在山區的冷浸田,一般在插秧後20tianzuoyouchuxianfabinggaofengqi。yejibuzhongmaixianhuanghua,houchenghuanghongsehuohonghesebandian,yepianbianzhai,yemaifacuiyiduan,yepianlaohuajiaokuai,xinyechangchusudumanbingyepianxizhai,jibuhezhongmaishilvbianhese。keyongliusuanxindengfeiliaojinxingbujiu,ruyong0.1%的硫酸鋅進行多次葉麵噴施,效果很好。
肥害或藥害引起發黃
氨水、碳(tan)酸(suan)氫(qing)銨(an)等(deng)肥(fei)料(liao)以(yi)及(ji)農(nong)藥(yao)如(ru)施(shi)用(yong)不(bu)當(dang),會(hui)引(yin)起(qi)中(zhong)毒(du)發(fa)黃(huang),導(dao)致(zhi)成(cheng)塊(kuai)成(cheng)片(pian)稻(dao)葉(ye)變(bian)成(cheng)鮮(xian)黃(huang)色(se)或(huo)金(jin)黃(huang)色(se),有(you)時(shi)黃(huang)葉(ye)上(shang)有(you)焦(jiao)灼(zhuo)斑(ban)。藥(yao)害(hai)嚴(yan)重(zhong)時(shi),葉(ye)片(pian)出(chu)現(xian)斑(ban)點(dian),失(shi)綠(lv)、焦灼或枯萎、或(huo)黃(huang)化(hua),有(you)的(de)甚(shen)至(zhi)全(quan)株(zhu)枯(ku)死(si)。若(ruo)發(fa)現(xian)及(ji)時(shi),田(tian)中(zhong)可(ke)立(li)即(ji)灌(guan)深(shen)水(shui),或(huo)向(xiang)稻(dao)株(zhu)噴(pen)灑(sa)清(qing)水(shui),可(ke)減(jian)輕(qing)藥(yao)害(hai)程(cheng)度(du)。此(ci)外(wai),肥(fei)害(hai)或(huo)藥(yao)害(hai)發(fa)生(sheng)後(hou)要(yao)追(zhui)施(shi)尿(niao)素(su)等(deng)速(su)效(xiao)肥(fei)料(liao),以(yi)增(zeng)強(qiang)作(zuo)物(wu)長(chang)勢(shi),增(zeng)強(qiang)抵(di)抗(kang)能(neng)力(li)。
病害侵染引起發黃
白葉枯病危害引起黃葉:一yi般ban先xian表biao現xian在zai葉ye片pian的de葉ye尖jian或huo葉ye緣yuan上shang,先xian是shi產chan生sheng黃huang綠lv色se或huo暗an綠lv色se斑ban點dian,後hou沿yan著zhe葉ye脈mai擴kuo展zhan成cheng斑ban條tiao,呈cheng灰hui白bai色se,病bing部bu與yu健jian部bu分fen界jie明ming顯xian,病bing斑ban上shang常chang有you黃huang褐he色se的de“菌膿”。
細菌性條斑病危害引起黃葉:心葉黃褐色枯死似假枯心苗,葉片、葉鞘上有褐色條斑,病斑上折斷中脈後可見黃色“菌膿”。後期感病時,葉片頂部至半片葉以上枯黃,遠望一片火紅。
水稻細菌性基腐病危害引起黃葉:心葉凋萎卷縮,有的已經變黃枯死,似二化螟、三化螟危害造成的枯心苗,但莖基部常發黑,莖節變硬變脆,易折斷且有一股腐臭味。
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