灌水量和追氮方式对春小麦生态化学计量特征的影响

Effect of Irrigation Amount and Nitrogen Fertilization Methods on Ecological Stoichiometry of Spring Wheat

为探索陇中黄土高原丘陵沟壑区春小麦适宜水氮管理模式,在甘肃省定西市安定区李家堡乡开展大田试验,测定分析不同灌水量(W1:50 mm,W2:100 mm,W3:150 mm)和不同时期追氮(N1:孕穗初期追氮40 kg·hm^-2,N2:灌浆初期追氮40 kg·hm^-2,N3:孕穗期初期和灌浆初期各追氮20 kg·hm^-2)下春小麦各生育时期根、茎、叶的碳(C)、氮(N)、磷(P)元素含量、化学计量特征及其与产量之间的关系。结果表明,随着春小麦生长发育,根系C含量呈逐渐升高趋势,茎和叶C含量呈先升后降趋势,各器官P含量均呈逐渐降低趋势。灌水量和追氮对春小麦根茎叶的C、P含量影响均不显著;同一追氮方式下,春小麦N含量、N/P值随着灌水量的增加而增大,C/N值随着灌水量的增加而降低。C/P值不随外界环境因子的变化而变化,表现出强烈的内稳性。在同一灌水量下,孕穗期和灌浆期分两次追施氮肥处理的N含量、N/P值最大,春小麦单株生物量和籽粒产量与N含量、N/P值呈正相关。因此,在陇中黄土高原丘陵区小麦地,在灌水150 mm时,孕穗期和灌浆期各追施氮肥20 kg·hm^-2,更有利于提高小麦的产量和保持化学元素的平衡。

To explore a suitable water and nitrogen management measure for spring wheat in the Loess Plateau Hilly-gully region of central Gansu,a field experiment was conducted in the Lijiabao town,Anding district of Dingxi city,Gansu province.The objective of this study is to determine the effects of different irrigation levels and nitrogen fertilization on carbon(C),nitrogen(N),and phosphorus(P)concentrations as well as their stoichiometry of roots,stems,and leaves of spring wheat at different growth stages.The treatments contains three irrigation levels(W1:50 mm,W2:100 mm,W3:150 mm)and three nitrogen fertilization methods(N1:one-time nitrogen topdressing 40 kg·hm^-2 at the beginning of booting,N2:one-time nitrogen topdressing 40 kg·hm^-2 at the beginning of filling,N3:initial booting and early filling field experiment of applying nitrogen and nitrogen of 20 kg·hm^-2).Results showed that root C concentrations were gradually increased,while C concentrations in stem and leaf were increased and then decreased with the growth and development of spring wheat.Mean-while,P concentrations in three organs were gradually decreased.In addition,both nitrogen fertilization levels and irrigation amount have no significant effects on C and P concentrations in spring wheat.At different irrigation levels,N concentrations and the N/P ratio in spring wheat were gradually increased,but the C/N ratio decreased with increasing the irrigation amount.Additionally,there was no clear variation in the C/P ratio with external environmental factors,which showed a strong inner stability.At different nitrogen fertilization levels,N concentrations and the N/P ratio were greatest at booting stage and filling stage when applied nitrogen twice.Individual biomass and grain yield of spring wheat were positively correlated to N concentrations and the N/P ratio.Therefore,when the irrigation was 150 mm and the topdressing nitrogen fertilizer application was 20 kg·hm^-2,it would be more beneficial to increase yield and promote the balance of chemical elements in wheat in the semi-arid Loess plateau.