CO2浓度升高和不同氮肥水平下源库处理对粳稻茎鞘非结构性碳水化合物积累和转运的影响

为探究CO₂浓度升高和不同氮肥水平下源库处理对粳稻茎鞘非结构性碳水化合物(NSC)积累和转运的影响,利用开顶式气室(OTC),设置2个CO₂浓度(CO₂]):对照(背景大气,aCO₂])和在背景大气CO₂]基础上升高200μmol·mol^-1(eCO₂])。以常规粳稻"南粳9108"为试验材料,在OTC内采用盆栽方式,设置低N(N1,10 g N·m^-2)、中N(N2,20 g N·m^-2)和高N(N3,30 g N·m^-2)3个施N水平。抽穗期源库改变设剪叶(LC)和疏花(SR)处理,以不处理为对照。测定并计算了抽穗期和成熟期叶片N含量、茎鞘NSC积累量(TM_NSC)、NSC表观转运量(ATMNSC)及其对籽粒产量的表观贡献率(AC_NSC)。采用方差分析、相关分析和逐步回归方法对上述观测数据进行分析。结果表明,CO₂]升高显著降低抽穗期叶片N含量,显著促进中N水平的NSC积累。在不同CO₂]和N水平下,SR处理均导致成熟期茎鞘TM_NSC显著升高,ATM_NSC和AC_NSC显著降低;在背景大气和不同N水平下,LC处理均显著降低成熟期TM_NSC,显著提高ATM_NSC,但CO₂]升高下LC处理对成熟期TM_NSC和ATM_NSC均无显著影响。LC处理对籽粒产量及其构成未产生显著影响。粒叶比越高,成熟期TM_NSC和千粒重越低,ATM_NSC、AC_NSC、籽粒产量和收获指数越高。综合影响AC_NSC的因素为粒叶比、抽穗期和成熟期TM_NSC;综合影响籽粒产量的因素为粒叶比、成熟期叶片N含量和TM_NSC,这些综合影响均可用多元回归模型定量表述。

Effects of source-sink manipulation on the accumulation and translocation of non-structural carbohydrates in stems and sheaths of Japonica rice under elevated CO2 concentration and different nitrogen fertilization levels

We investigated the effects of source-sink manipulation on the accumulation and translocation of non-structural carbohydrates(NSC)in the stems and sheaths of a Japonica rice(Oryza sativa L.)cultivar"Nangeng 9108"under elevated CO₂concentration(CO₂])and different nitrogen(N)fertilization levels.There were two CO₂concentrations-ambientCO₂](aCO₂])and aCO₂]+200μmol·mol^-1(eCO₂])-in open-top chambers(OTCs),and three N application rates,low N(N1,10 g N·m^-2),medium N(N2,20 g N·m^-2),and high N(N3,30g N·m^-2).The source-sink manipulations were carried out by leaf cutting(LC)and spikelet removal(SR).No source-sink manipulations were set as control(CK).Leaf N content and the total mass of NSC stored in stems and sheaths(TM_NSC)at heading and maturity were measured.The apparent transferred mass of NSC from stems and sheaths to grains(ATM_NSC)and the apparent contribution of transferred NSC to grain yield(AC_NSC)were calculated.The results showed that eCO₂]significantly decreased leaf N content at heading stage,and significantly promoted NSC accumulation at the N2 level.Under differentCO₂]and N levels,SR treatment increased TM_NSCat maturity but decreased ATM_NSCand AC_NSC.LC treatment significantly decreased TMNSC and increased ATM_NSCat maturity under aCO₂]and different N levels.There were no significant effects of LC treatment on TM_NSCand ATM_NSCat maturity under elevated CO₂.The LC treatment did not affect grain yield and its components.We found higher ratio of spikelet number to leaf area(grain/leaf ratio),higher ATM_NSC,AC_NSC,grain yield and harvest index but lower TM_NSC and 1000-grain weight at maturity.The factors affecting AC_NSCwere grain/leaf ratio,and TM_NSCat heading and maturity,while those affecting grain yield were grain/leaf ratio,leaf N content and TMN_SCat maturity.The relationships between ACN_SCand grain yield can be quantified by multiple regression models.