局部硝态氮供应对不同品种小麦侧根发育的影响

Effects of local nitrate supply on lateral root development of different wheat varieties

小麦为须根系植物,根系发生发育除了受遗传因素控制外,还受环境因素的影响。研究局部供应硝态氮对小麦侧根发生发育及植株氮素吸收的影响,可为小麦品种选育,增强小麦吸收硝态氮、提高氮素吸收效率提供技术支撑和理论基础。选择4个小麦品种,H10、L14、衡观35和石麦15,开展盆栽试验,设置3个施氮水平:N0、94.5、473.5 kg/hm2,研究硝态氮供应对不同品种小麦生物量和地上部氮素积累量的影响;进行营养液分根培养试验,两侧设置6个施氮处理:0/0、0/2.5、0/50、2.5/2.5、2.5/50和50/50 mmol/L,研究局部供应硝态氮对小麦侧根发生发育及植株氮素吸收的影响。研究发现,(1)小麦H10和衡观35在473.5 kg/hm2高氮处理下生物量和地上部氮素积累量最大,L14和石麦15相对较小。(2)分根培养条件下,两侧均施50.0 mmol/L硝态氮小麦地上部干重与氮浓度明显高于两侧不施硝态氮处理。2.50 mmol/L处理一侧衡观35根干重和侧根密度高于不施硝态氮一侧,而L14在50.0 mmol/L硝态氮处理一侧根干重较大、侧根密度较高。施用2.50 mmol/L硝态氮一侧H10、衡观35和石麦15的侧根长度和侧根平均长度明显高于不施硝态氮一侧,并以石麦15侧根伸长倍数最大。与不施硝态氮一侧相比,50.0 mmol/L硝态氮一侧4个小麦品种的侧根长度、侧根平均长度均较长,以H10侧根伸长倍数最大。(3)局部供应硝态氮,明显促进小麦侧根伸长。诱导效应越大,小麦植株地上部氮累积越高。

The wheat is a plant with fibrous root.Its root system consists of radicle(seed root),nodal root(secondary root)and lateral root.Lateral root development of plants is not only controlled by genetic factors,but also affected by environmental factors.The study of investigating the development of lateral roots and nitrogen uptake in plants as influenced by local nitrate supply could provide technical support and theoretical basis for the selection and breeding of wheat varieties and increasing nitrogen absorption efficiency.Four wheat cultivars including H10,L14,Hengguan 35 and Shimai 15,were selected as the tested crops.Pot experiment was conducted with three nitrogen application rates of 0,94.5,473.5 kg/hm2 to study their effects on biomass and aboveground nitrogen accumulation in different varieties of wheat.Nutrient solution split-root culture experiment was conducted with six treatments in two sides with nitrate supply levels of 0/0,0/2.5,0/50,2.5/2.5,2.5/50 and 50/50 mmol/L.The results showed that:(1)the biomass and nitrogen accumulation in four varieties of wheat shoots were different under three nitrogen applications.H10 and Hengguan35 had higher biomass and nitrogen accumulation in shoots with the high nitrate treatment.L14 and Shimai 15 had higher biomass and nitrogen accumulation in shoots with the no nitrate treatment.(2)Under the addition of 50.0 mmol/L nitrate in both compartments,dry matter weight and nitrogen concentration of wheat shoots were higher in comparison to those without nitrate supply.More root biomass and lateral root density of Hengguan 35 were in the compartment with 2.50 mmol/L nitrate treatment than those without nitrate addition,while for the wheat cultivar L14,the 50.0 mmol/L nitrate increased root biomass and lateral root density in the nitrogen applied side.In the side with 2.50 mmol/L nitrate application,total lateral root length and average lateral root length of three wheat genotypes H10,Hengguan 35 and Simai 15 were higher than those of no nitrogen side.The stimulatory effect of 2.50 mmol/L nitrate on lateral root elongation was the highest in Shimai 15.Compared with the side without nitrate,total lateral root length and average lateral root length of four wheat genotypes were longer in the side with 50.0 mmol/L nitrate application.The highest increase of lateral root elongation under 50.0 mmol/L nitrate treatment was found in H10.(3)In the root split treatments,nitrogen concentration in wheat shoots was positively correlated with the increase rates of the average lateral roots length induced by nitrate supply,suggesting that localized nitrate supply could stimulate later root elongation of wheat,which would benefit plant nitrogen uptake.Local supply of nitrate obviously promoted the elongation of the lateral roots of wheat,and the induction effect was different between four wheat varieties.The greater inducing effect could benefit for nitrogen accumulation of wheat plants.