施氮量和播种密度对不同熟期油菜干物质量和产量的影响

为探究不同熟期油菜在施氮量和密度互作下的干物质积累、分配、对籽粒贡献与产量效应,以不同熟期(早熟和晚熟)油菜品种为试验材料,于2015-2016年在简阳进行品种、氮肥与密度三因素多水平的田间试验。结果表明,密度对干物质积累、分配和对籽粒贡献的影响总体均大于施氮量。在密度和氮肥互作效应下,干物质积累量的改变量总体上表现为成熟期>花末期>盛花期>初花期>苗期,且随着施氮量的增加而增加,随着密度的增大而显著减少,其中晚熟品种对密度和施氮量的变化更为敏感;干物质分配率在花期前、花期、成熟期最大差异分别表现在叶片、茎秆、角果。在相应生育期,随着密度的增大,叶片分配率显著递减,而茎秆、角果的分配率则显著递增;干物质贡献量随着密度增大而减少,晚熟品种较早熟品种的降幅大,随着施氮量增加晚熟品种干物质贡献量呈上升趋势,早熟品种干物质贡献量花前呈上升趋势,花后呈先增加后下降趋势(除低氮处理外)。在低氮(120 kg·hm^-2)、中氮(240 kg·hm^-2)下,随着密度的增大,产量呈先上升后下降趋势;高氮(360 kg·hm^-2)条件下,随着密度增大,产量显著递增;早熟品种的产量在中氮(240 kg·hm^-2)下达到最高,平均为2 244.75 kg·hm^-2;晚熟品种的产量在高氮(360 kg·hm^-2)下达到最高,平均为2 472.15 kg·hm^-2;早熟品种最佳密肥组合为240 kg·hm^-2和30~45万株·hm^-2,晚熟品种最佳密肥组合为360 kg·hm^-2和30~45万株·hm^-2。综上,氮肥和密度主要通过改变干物质积累量和花后干物质贡献量来影响产量,晚熟品种更易通过调节氮肥和密度等手段实现高产量。本研究结果为不同熟期油菜氮肥及密度管理提供了理论依据。

Effects of Densities and Nitrogen Fertilizer on Dry Matter and Yield of Different Maturity Rapeseed

The objective of this study was to explore effectof nitrogen fertilizer and plant densities on dry matter accumulation, allocation, contribution to grain and yield for different maturity rape seed. (Based on the different maturity rape seed learly and late-maturing varieties), a multi-level field experiment of variety, nitrogen fertilizer and density was carried out in Yucheng village, Jianyang City, Sichuan Province in 2015-2016. The results showed that densityplayed a more significant role thannitrogen fertilizer on dry matter accumulation, allocation and contribution to grain. The variation of dry matter accumulation under the effect of density and nitrogen fertilizer interaction was generally followed the order of mature stage>flowering stage>flowering stage>early flowering stage>seeding stage. Dry matter accumulations increased with the increasing of nitrogen fertilizer, but a downward trend was observed with the increasing of planting density and the late maturing varieties were more sensitive to the change of density and nitrogen fertilizer. The effects of nitrogen fertilizer and density on dry matter allocation rate were very difference at different growth stages. Leaves proportion showed the largest difference before anthesis, and stem and pod proportion were the highest at anthesis and maturity stage. The stems and pods proportion wre significantly improved with the increasing of density, while the leaves decreased. The amount of dry matter contribution to grain during pre-anthesis and post-anthesis were decreased with the increasing of density and the decline rate of late maturing varieties was much lager. The amount of dry matter contribution to grain of different maturing varieties was different with the increasing of nitrogen fertilizer. The amount of dry matter contribution to grain of early-maturing variety were increased during pre-anthesis and decreased during post-anthesis with the increasing of nitrogen fertilizer (except for low nitrogen treatment), while the late-maturing variety were increased with the increasing of nitrogen fertilizer during pre-anthesis and post-anthesis. The grain yield of rapeseed increased at first and then decreased with the increase of density under the condition of both low nitrogen (120 kg·hm^-2) and medium nitrogen (240 kg·hm^-2), while under high nitrogen (360 kg·hm^-2), grain yield significantly increased as density increased. At the same density, the grain yield of the early-maturing variety increased first and then decreased with the increase of nitrogen fertilizerand the highest yield was under medium nitrogen (240 kg·hm^-2) with an average of 2 244.75 kg·hm^-2, while the late-maturing variety significantly increased with the increase of nitrogen fertilizerand the highest yield was under high nitrogen (360 kg·hm^-2) with an average of 2 472.15 kg·hm^-2. For the early-maturing variety, the optimum combination is N 240 kg·hm^-2 plus density of 30×10⁴~45×10⁴plants·hm^-2, and N 360 kg·hm^-2 plus density of 30×10⁴~45×10⁴plants·hm^-2for the late-maturing variety.The study indicated that the yield was mainly affected by dry matter accumulation and contribution to grain between post-anthesis in changing the amount of nitrogen fertilizer and density. It is easier to achieve the optimalyield by changing nitrogen fertilizer dosage and density in the late-maturing varieties. The findings will provide atheoretical basis for nitrogen fertilizer and density management in different maturing rape varieties.