【作者】 季书勤；

【导师】 曹卫星；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2000， 硕士

【摘要】 通过近10年的多年多点试验，研究了在不同产量水平、不同密度、不同品种类型、不同有机肥用量基础上，前氮后移对小麦产量形成及生育特性的影响，结果表明： 1、氮肥后移对小麦抽穗前各生育期的出现日期没有影响，主要差别表现在小麦抽穗开花至成熟期，与前重施氮肥相比，后重施氮结合浇水，抽穗开花期无差别或提前1d，成熟期一般推迟1-2d，从而延长了灌浆期。在成熟前的一周内，千粒日增重明显高于对照，最终千粒重提高。这主要是因为前氮后移可以维持灌浆后期旗叶、倒二叶有较高的叶绿素含量，灌浆期有较高的叶面积系数。 2、亩产量在400kg左右，亩施N素20kg以下，返青期、拔节期或药隔期追施一定比例的N素化肥，均比N肥全部底施增产，产量三要素两增一平（或略减）。亩产量达到500kg左右时，拔节～药隔期追施N素的产量高于返青期追肥。随着肥力水平和产量水平的提高，追N时期应随之后移，但仍以不晚于挑旗为好。如果从经济高效的角度来说，以拔节期+药隔期至挑旗两次追肥最好。但在亩产400kg、基本苗偏少（10万/亩以下）的条件下，氮肥运筹以前重后轻方式，利于增加亩成穗数，促进产量提高。 3、前氮后移由于减少了底N肥用量，可降低最高群体，减少无效生长，有效缓解拔节期田间荫蔽的矛盾。中后期适时追肥浇水，可以提高分蘖成穗率，巩固亩成穗数，增加穗粒数和千粒重， 4、前氮后移可以缩短基部第一、二节间长度，提高其充实度，增加穗下节长度。同时还可以提高小麦植株及穗的整齐度。 以上结果对于多穗型品种、中穗型品种都是适用的。但对于大穗型品种和大粒型品种影响却不尽一致。更多还原

【Abstract】 The effect of postponing the N～ertilizer applying time on yield formation , and growing and development characteristics of wheat was studied for ten years in succession, on the basis of different yield levels, variety types, densities and organic manure applying amounts. The results were as follows: 1. The postponement of N～ertilizer applying time had no effect on wheat growing and developing dates before heading, but the difference appeared after it. Compared with earlier N?fertilizer application, the date of earring and flowering for later N?fertilizer application was unchanged or one day earlier, but the mature date was put off for 1 2d, so the grain filling period of was increased corresponding. The grain filling rate was also higher than ck during one week period before mature, which lead to an increase of 1000ernel weight eventually. This may be attributed to the higher chlorophyll level in flag leaves and the second leaves, and also the higher leafarea coefficient in filling period. 2.At yield level of 400 kg/mu and under 20 kg/mu of N, a certain proportion of N was applied at reviving stage, elongatiop stage or late elongation stage, compared with applying all the N as base fertilizer, could contributed to raise wheat yield, because 2 of the three yield factors increased and the other one kept unchanged or a little decreased. When wheat yield level reached to some 500 kg/mu, the grain yield for applying N at elongation late elongation was higher than that at reviving. This showed that, with the improvement of soil fertility and yield level, the time of applying Nertilizer should be postponed, but better not later than booting stage . If high economic and beneficial result was considered, two times of top application separately in 42 e1ongation and booting were the best. However, in the condition of yie1d1eve1 under 400 kg/mu and fundamenta1 seed1ing 1ess than 0. 1 mi1l ion/mu,the date of app1ying N shou1d be moved up, in order to increase the ears/mu,and then improve grain yie1d.3. When a certain proportion of N--ferti1izer was used as 1atertop dressing, the amount of basic ferti1izer was cut down at the sametime, which cou1d he1p to decrease the high seed1ing popu1ation andinva1 id growth, so the contradiction of fo1 iage shading at e1ongationstage was a11eviated effect ive1y. App1yi ng fert i 1 izer and irri gat ion atthe right moment of midd1e and later growing stage cou1d improve thepercentage of ear bearing ti l lers, steady the ears/mu and increase thegrains/sPike and l000--kernel weight.4. Postponing the time of N top appl ication cou1d shorten tbe firstand second interned 1ength in basa1 portion, prove their so1 id degreeand increase the 1ength of ear interned. I t cou1d a1 so improve the uni formof plant height and ear layer.The resu1t above is applying to both mu1tiple-- and midd1e--sPikevarieties, but not to big --eaI’ and b1g kerne1 var1eties.更多还原