启动氮加追肥对氮在大豆体内积累分配规律及产量的影响

采用框栽试验方法,在施用等量氮(纯N 50 kg.hm-2)条件下设置基肥一次性施用(对照);R3或R4期一次性追肥;启动氮15 kg加R3或R4期追氮35 kg共5个处理,研究启动氮加追肥对氮在大豆体内积累分配规律及产量的影响。结果表明,在R5期,与对照相比,启动氮15 kg加R4期追氮35 kg处理叶片N积累量减少11.5%,荚果N积累量增加36.6%(P<0.05);而根系N积累量增加21.7%(P<0.05),根瘤N积累量增加64.2%(P<0.05),表明启动氮加追肥处理N运转通畅,可以满足籽粒充实期大豆对氮素的需求。在R4～R8期,启动氮加R3或R4期追氮处理的氮积累量分别比基肥一次性施用处理增加82.6%和105%(P<0.01)。启动氮加R3或R4期追氮35 kg处理单株粒数分别较对照增加14.8%和15.8%(P<0.01),产量分别增加17.6%和19.9%(P<0.01)。大豆植株R4～R8期氮积累量与产量呈极显著正相关(r=0.795**),提高结荚鼓粒期后大豆氮素积累量是增加大豆产量的关键。

Nitrogen Accumulation, Distribution and Yield of Soybean as Affected by Starter-N plus Topdressed N

In order to get a better understanding of the effects of starter-N plus topdressed N on N accumulation,distribution and yield of soybean,a pot experiment was conducted with 5 different N application times under the rate of N 50 kg·ha-1:all N as basal fertilizer(A),all N as topdressing at R3/R4 stage(B,C),N 15 kg as basal fertilizer and 35 kg as topdressing at R3/R4 stage(D,E).Results are shown as follow:at R5 stage,N accumulation(NA)in leaves of E was 11.5% lower than A,yet NA in nodules of E was 36.6% greater than A,suggesting that a smooth N transportation was ensured by E.NA in roots and pods of E were 21.7% and 64.2% greater compared to A(P<0.05)respectively,indicating that N demand of seeds after R5 stage could have been met by starter-N combined with topdressing.NA in whole plant of D and E was 82.6% and 105% greater than A(P<0.01)respectively at R4-R8 stages.There was a significant positive correlation between NA in R4-R8 stages and soybean yield(r=0.795**),and the improvement of NA after R4 stage was very important in achieving soybean yield potential.Seeds per plant of D and E was 14.8% and 15.8% greater than A(P<0.01),respectively,and yield of D and E was 17.6% and 19.9% greater than A(P<0.01),respectively.