CO_2浓度升高和施氮对冬小麦花前贮存碳氮转运的影响

Effect of Elevated CO_2 Concentration and Nitrogen Application on Translocation of Dry Matter and Nitrogen Restored before Anthesis in Winter Wheat

为探讨大气CO2浓度升高对冬小麦花前贮存碳氮转运的影响及氮素营养的调节作用,以小偃22和小偃6号为材料,于2007-2009连续2个生长季,利用开顶式气室进行盆栽试验,对背景CO2浓度(375μLL-1)和高CO2浓度(2007-2008年度680μLL-1,2008-2009年度750μLL-1)条件下不同施氮处理的干物质和氮素在籽粒、花前地上部中的累积以及花后营养器官的转运进行了评价。2007—2008年度设4个施氮水平,分别是0、0.1、0.2和0.3gkg-1土;2008—2009年度设3个施氮水平,分别是0、0.15和0.30gkg-1土。结果表明,施氮和CO2浓度升高促进了干物质和氮素在籽粒和花前营养器官的积累,增加了花前营养器官和地上部贮存干物质和氮素向籽粒的转运量,适量施氮提高了CO2浓度升高对花前营养器官干物质和氮素累积以及花后向籽粒转运的正向效应。与背景CO2浓度相比,高CO2浓度提高了花前营养器官和地上部干物质对籽粒产量的贡献率和转运率,但CO2浓度升高对花前氮素的贡献率和转运率的影响因年份和品种而异。CO2浓度升高后,2007-2008年度各营养器官和地上部,以及2008-2009年度茎鞘和穗的氮素贡献率和转运率均增加,但2008-2009年度2个品种叶片和地上部氮素贡献率在施氮时均显著降低,小偃22叶片和地上部氮素转运率在各施氮水平下以及小偃6号地上部氮素转运率在0.13gkg-1土施氮水平下均明显增加。适量施氮也在大多数情况下增强了CO2浓度升高对营养器官干物质和氮素的贡献率和转运率的正向效应。说明CO2浓度升高后小麦产量和氮素积累增加与其促进花前干物质和氮素积累及花后向籽粒的转运密切相关。

Either CO2 enrichment or nitrogen （N） application has effects to increase grain yield, as well as dry matter and N ac-cumulation in winter wheat （Triticum aestivum L.）. To understand the effects and interaction of both factors on dry matter and N restored before anthesis and translocated from vegetative organs into grains, we carried out a pot experiment across two cropping seasons using wheat cultivars Xiaoyan 22 （2007–2008） and Xiaoyan 22 and Xiaoyan 6 （2008–2009）. Wheat cultivars were grown in open top chambers （OTCs） under conditions of ambient CO2 concentration （AT, 375 μL L-1） and elevated CO2 concentration （ET, 680 μL L-1 in 2007–2008 and 750 μL L-1 in 2008–2009）. N fertilizer was applied at levels of 0, 0.1, 0.2, and 0.3 g kg-1 soil in 2007–2008 and 0, 0.15, and 0.30 g kg-1 soil in 2008–2009. Accumulation and translation of dry matter and N in pre-anthesis vegetative organs （stem ＋ sheath, leaf blade, and spike） and shoot in all treatments were measured. CO2 enrichment and N nutri-tion improvement increased dry matter and N accumulation in grain and pre-anthesis vegetative organs, and translocation amounts of dry matter and N from vegetative organs and shoot into grains. The reasonable N application promoted the positive effects of CO2 concentration on dry matter and N accumulation and translocation. Compared to AT, ET advanced the contribution and translocation rates of dry matter from vegetative organs and shoot into grains. The effects of CO2 enrichment on the N contribu-tion and translocation rates in vegetative organs and shoot were different among years and cultivars. Elevated CO2 increased the N contribution and translocation rates in every vegetative organ and shoot in 2007–2008 cropping season and those in stem ＋ sheath and spike in 2008–2009 cropping season. However, in 2008–2009 cropping season, elevated CO2 reduced the N contribution rate in leaf blade and shoot of both cultivars under N levels of 0.15 and 0.30 g kg-1. The N translocation rates of leaf blade and shoot were increased in Xiaoyan 22 under all N levels and only the N translocation rate of shoot was increased in Xiaoyan 6 under N level of 0.3 g kg-1. The interaction between CO2 concentration and N nutrition positively affected the contribution and translocation rates of dry matter and N in vegetative organs and pre-anthesis shoot in most cases. This result suggested that elevated CO2 enhanced grain yield and N accumulation through promoting accumulation before anthesis and translocation after anthesis of dry matter and nitrogen in vegetative organs and shoot in some way.