[Objective]The purpose of this study is to elucidate morphological and physiological mutual beneficial mechanism for compact type maize hybrid under nitrogen and density interaction, for further raise overall productivity of density tolerant maize hybrid.[Method]Plant morphological trait, ear leaf photosynthetic ability and yield were determined under field experimental condition in 2014 and 2015. Split-split plot design, 2 plant type hybrids (compact plant type and flat plant type) as the main plot, 3 nitrogen treatments (N1: 0, N2: 90 kg N·hm-2 and N3: 180 kg N·hm-2) as the split plot, 3 plant densities (D1: 45000 plant/hm2, D2: 60000 plant/hm2 and D3: 75000 plant/hm2) as the sub-split plot.[Result]The effects of nitrogen on internode length, leaf angle, SPAD value, kernel weight per ear and yield were stronger than that of density on those parameters. Stem diameter,Pn and kernel number per ear was sensitive to density increasing. Compared with flat type hybrid, decreased range of stem diameter was small, and response sensitivity from 1 to 3 internode length was slowness with plant density increased for compact type hybrid. However, the 1-3 internode length was shortened significantly with nitrogen input amount increased (PN2→N3=0.004-0.028), negative response range of 4-5 internode length for compact type hybrid (10.9%) was higher than positive response range of 4-5 internode length for flat type hybrid (3.3%). Leaf angle of compact type hybrid was down to 2.9°±1.1° with nitrogen input. The leaf angle of leaf below ear leaf changed to a relatively lower with plant density increased. Response peak value of SPAD to nitrogen for compact type hybrid (N3) was higher than that for flat type hybrid (N2). The negative effect of Pn caused by density increasing was relatively small for compact type hybrid. SPAD and Pn of ear leaf for compact type hybrid were higher than that for flat type hybrid in N3 and D3 treatment. Altogether, the effect of nitrogen and density interaction on kernel number and kernel weight per ear for compact type hybrid was smaller than that for flat type hybrid. Harvest index of compact type hybrid was relatively high, which the difference between N×D interaction treatment (P N1→N3 =0.16,PD1→D3 =0.12) was no significant, however, that the difference between that (P N1→N3 =0.03,P D1→D3<0.01) of flat type hybrid was very significant. The highest yield record was obtained in N3D3 and N3D1 treatments for compact and flat type hybrid, respectively. And their yield gain ratio for density and nitrogen was 1﹕2.3 and 1﹕4.0, respectively.[Conclusion] Compared with flat type hybrid, compact type hybrid had a more adaptable ability of regulating cross and longitudinal growth of basal part of stem. Nitrogen application could reduce leaf angle of leaf above ear leaf, ear leaf and leaf below ear leaf, which could enhance ear leaf light use efficiency. Proper morphophysiological coordinate ability keeps a higher dry matter transfer rate for the compact type hybrid under higher density and higher nitrogen fertilizer condition at kernel weight formation stage, thus achieving a higher population yield.%[目的]阐明不同株型玉米在氮素和密度互作下获得高产的形态生理互利机理,进一步提升密植玉米综合生产力.[方法]2014—2015年,在大田条件下,采用裂-裂区试验设计,以不同株型玉米品种为主区,氮素(N1:0,N2:90 kg N·hm-2和N3:180 kg N·hm-2)为裂区、密度(D1:45000株/hm2,D2:60000株/hm2和D3:75000株/hm2)为裂裂区,测定了植株形态、叶片光合性能和产量等指标.[结果]施氮对节间长度、叶倾角、叶色值、粒重和产量的影响程度均高于密度调控,茎粗、光合速率和穗粒数对增密响应程度较高.与平展型玉米相比,紧凑型玉米茎粗随密度提高降幅较小,第1—3节间长度对增密响应迟钝,随施氮量增加显著缩短(PN2→N3=0.004—0.028),第4—5节间长度对增密的负响应幅度(10.9%)均高于平展型玉米同节间长度对其的正响应幅度(3.3%).施氮可降低紧凑型玉米棒三叶叶倾角2.9°±1.1°,增密后,其穗下叶叶倾角降幅较高.紧凑型玉米叶色值对施氮量的响应峰值(N3)高于平展型玉米(N2),增密对其光合速率的负效应相对较小,在N3和D3处理下,其叶色值和光合速率均高于平展型玉米.紧凑型玉米穗粒数与粒重受氮密调控影响比平展型玉米小,其收获指数较高,且在氮/密处理间差异均不显著(PN1→N3=0.16,PD1→D3=0.12),而平展型玉米在氮/密处理间差异均达显著或极显著水平(PN1→N3=0.03,PD1-D3<0.01).紧凑型玉米和平展型玉米分别在N3D3和N3D1处理下获得较高产量,增密和施氮对其籽粒产量的贡献比分别是1﹕2.3和1﹕4.0.[结论]与平展型玉米相比,紧凑型玉米茎基部横/纵向生长对氮密协同提高具有较强的适应能力,施氮可降低紧凑型玉米棒三叶叶倾角,提高穗位叶光合性能.紧凑型玉米在高密高氮处理下较好的形态生理协调性保证了生育后期相对较高的物质转化效率,最终获得较高群体产量.
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