一、深陷僵苗。據筆者近些年的調查,這類僵苗最為普遍,多見於犁耙次數過多、泥(ni)巴(ba)過(guo)糊(hu)的(de)稻(dao)田(tian),這(zhe)種(zhong)田(tian)土(tu)壤(rang)通(tong)透(tou)性(xing)差(cha),耕(geng)層(ceng)缺(que)氧(yang),尤(you)其(qi)是(shi)在(zai)翻(fan)耕(geng)後(hou)立(li)即(ji)拋(pao)栽(zai),極(ji)容(rong)易(yi)出(chu)現(xian)深(shen)陷(xian)發(fa)僵(jiang)現(xian)象(xiang)。它(ta)一(yi)方(fang)麵(mian)推(tui)遲(chi)了(le)分(fen)蘖(nie)時(shi)間(jian),另(ling)方(fang)麵(mian)又(you)會(hui)導(dao)致(zhi)後(hou)期(qi)猛(meng)發(fa),加(jia)重(zhong)病(bing)蟲(chong)危(wei)害(hai)與(yu)倒(dao)伏(fu)。其(qi)表(biao)現(xian)特(te)征(zheng)是(shi)稻(dao)苗(miao)下(xia)沉(chen),苗(miao)成(cheng)簇(cu)立(li)狀(zhuang),根(gen)係(xi)變(bian)黑(hei),苗(miao)矮(ai)小(xiao),葉(ye)色(se)濃(nong),出(chu)葉(ye)速(su)度(du)緩(huan)慢(man)。隻(zhi)有(you)在(zai)根(gen)位(wei)上(shang)移(yi),出(chu)現(xian)“二、三盤根”後(hou),稻(dao)苗(miao)生(sheng)長(chang)才(cai)緩(huan)慢(man)恢(hui)複(fu)。預(yu)防(fang)深(shen)陷(xian)發(fa)僵(jiang),一(yi)是(shi)要(yao)提(ti)倡(chang)稻(dao)田(tian)耕(geng)耙(pa)下(xia)鬆(song)上(shang)平(ping),田(tian)麵(mian)平(ping)整(zheng),嚴(yan)防(fang)耕(geng)耙(pa)過(guo)糊(hu),在(zai)耕(geng)耙(pa)時(shi)要(yao)控(kong)製(zhi)犁(li)耙(pa)次(ci)數(shu),對(dui)冬(dong)泡(pao)田(tian),爛(lan)泥(ni)田(tian)可(ke)采(cai)用(yong)免(mian)耕(geng)拋(pao)秧(yang)方(fang)法(fa)。二(er)是(shi)切(qie)不(bu)可(ke)邊(bian)耕(geng)邊(bian)耙(pa)邊(bian)拋(pao)秧(yang),提(ti)倡(chang)排(pai)水(shui)落(luo)幹(gan)沉(chen)實(shi)後(hou)拋(pao)秧(yang)。也(ye)可(ke)在(zai)一(yi)犁(li)二(er)耙(pa)後(hou)拋(pao)秧(yang),即(ji)犁(li)耙(pa)後(hou)讓(rang)田(tian)泥(ni)沉(chen)實(shi)一(yi)天(tian)一(yi)夜(ye)才(cai)拋(pao)秧(yang)。三(san)是(shi)拋(pao)後(hou)露(lu)田(tian)促(cu)進(jin)發(fa)根(gen)紮(zha)針(zhen)立(li)苗(miao),並(bing)采(cai)用(yong)濕(shi)潤(run)灌(guan)溉(gai),幹(gan)幹(gan)濕(shi)濕(shi)促(cu)分(fen)蘖(nie),不(bu)能(neng)灌(guan)深(shen)水(shui)。
二、中毒僵苗。施用未經腐熟的有機肥,綠肥翻耕過遲或用量過大造成。由於有機質嫌氣分解,產生大量有機酸、liuhuaqingdengyouduyouhaiwuzhi,daozhidaomiaogenxifahei,chuxianfuniguqixianxiang,daomiaoaixiaozhili,shengchangtingzhi,bufennie。yepiandaiyouhesebandian,youxiaxiangshangfazhan,yanzhongshiquanzhusiwang。qiyufangcuoshi:一是適當提早綠肥的翻漚期,讓其有一個腐熟過程;施用的有機肥應充分腐熟,其畝施用量1.5噸左右,綠肥的用量也應控製在1.5-2dunzuoyou。ershibaozhenggengzuozhiliang,liqiutufeironghuo。paoyanghouzhuyiduolutian,cujincaoziheqitayoujifeidefulanfenjie。faxianzhongdujiangmiaodezaodaotiankuai,kejishishidangshaitian。
三、lenghaijiangmiao。paoyanghouyushangchixudiwenyinyuhuodafengdayutian,wenduxiajiangrongyichuxianlenghaijiangmiao,yibanlianpianfasheng,yangmiaofahuang,yanzhongshixiabulaoyekusi,shangbuyechuxianhumayebanbing,shutufaxingshenglixingbinghai。daihanchaoguohou,cainengzhubuhuifushengji。lingwai,zaishanqiuqudeyixielengjintian、爛泥田,由於地下水位高、水溫低,遇上寒潮更易出現冷害僵苗,嚴重製約早稻平衡增產。預防措施:一是注意天氣預報,選擇冷尾暖頭,天氣晴朗,氣溫在15℃以上,無大風大雨的天氣拋栽。拋栽時切忌蓄水過深,拋秧前1-2天對苗床控水,以利帶土拋秧,提高豎苗率。二是對冷浸田應加強改造,尤其是要開好四周排水溝,導除冷浸水,以提高泥溫。
四、缺素僵苗。這種僵苗主要發生在常年隻注重施氮肥,不施或少施磷肥的稻田,以及土壤pH值偏高(在7.8-8.4之間)的(de)石(shi)灰(hui)岩(yan)山(shan)區(qu)稻(dao)田(tian),這(zhe)類(lei)田(tian)磷(lin)易(yi)被(bei)固(gu)定(ding),有(you)效(xiao)磷(lin)缺(que)乏(fa),常(chang)造(zao)成(cheng)缺(que)磷(lin)發(fa)僵(jiang)。長(chang)期(qi)串(chuan)灌(guan)深(shen)灌(guan)冷(leng)泉(quan)水(shui)的(de)稻(dao)田(tian),鉀(jia)素(su)也(ye)易(yi)流(liu)失(shi),常(chang)因(yin)鉀(jia)素(su)流(liu)失(shi)而(er)引(yin)起(qi)僵(jiang)苗(miao),或(huo)兼(jian)有(you)冷(leng)害(hai)、中毒僵苗症狀。對這幾種缺素僵苗稻田,可對症增施磷肥或鉀肥,對拋栽早稻防僵苗促早發,有顯著增產效果。
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