黄淮区不同年代冬小麦主栽品种根系性状及氮素利用率的差异

Difference of Root Traits and Nitrogen Use Efficiency among Wheat Cultivars Released since 1950s in Huanghuai Area

为探明黄淮区冬小麦主栽品种的根系性状和氮素利用率的年代变化趋势,以12个不同年代主栽品种为材料,采用根袋盆栽方法,研究了根系形态、吸收能力与生产力及氮素利用率的年代差异。结果表明,随着年代的推进,小麦籽粒产量、生物量、氮肥偏生产力和氮素吸收效率显著提高,增长率分别为每年0.53%、0.38%、0.53%和0.59%,而氮素内部利用效率则呈下降趋势。小麦孕穗期和成熟期的根系总长、总表面积、总体积和平均直径均随着年代推移和品种改良呈显著下降趋势,其中成熟期的相应指标分别每年下降0.68%、1.48%、2.26%和0.78%;根系生物量和根冠比亦显著降低,而比根长则呈显著递增趋势。单位根表面积吸氮量随着年代推移而显著增加,平均每年增长2.09%。此外,近根区土壤硝态氮含量和硝化势随年代推移和品种更新有增加趋势。可见,近期小麦品种比早期品种在生产力和氮素利用效率上更具有优势,可能与根系生长冗余的降低、根系氮素吸收能力的增强、根冠关系的协调优化以及硝态氮营养的增强等有关。

In order to learn the changes of wheat root traits and nitrogen(N)use efficiency along with the cultivar improvement progress since 1950sin Huanghuai area,a rhizobox experiment was conducted with twelve cultivars.With the genetic improvement,wheat yield,biomass,N partial factor productivity and N uptake efficiency were increased significantly by 0.53%,0.38%,0.53%and 0.59%per year,while N utilization efficiency showed a slightly and insignificantly decreasing trend.During the same period,wheat root length,surface area,volume and average diameter at both booting and maturity stages declined significantly,with a corresponding annual decrease rate of 0.68%,1.48%,2.26% and 0.78% at maturity stage,respectively.Simultaneously,root biomass and root to shoot ratio declined significantly,while specific root length increased evidently.Additionally,N uptake per unit root surface area was enhanced by 2.09% per year along with the wheat cultivar renewal.Meanwhile,nitrate content and nitrification potential in soil near the roots exhibited significantly increasing trends with the genetic improvement.It is concluded that modern wheat cultivars performed much better both in productivity and N use efficiency than old cultivars,which might be associated with the reduction of root growth redundancy,the enhancement of root N uptake capacity,the improvement of relationship between root and shoot,and the enrichment of soil nitrate nutrient.