两种氮水平下CO2浓度升高对冬小麦生长和氮磷浓度的影响

预计到 2 1世纪末期大气CO2 浓度将会比目前水平增加 1倍 ,约 70 0 μmolmol- 1 左右。因此CO2 浓度升高对作物的影响研究十分重要。本文探讨在两种氮 (N)水平下 ,CO2 浓度升高对冬小麦 (TriticumaestivumL cv Xinong 872 7)生长和地上部N、磷 (P)浓度的影响及原因。试验设 3 5 0 μmolmol- 1 和 70 0 μmolmol- 1 两种CO2 浓度水平和 45kghm- 2 和 90kghm- 2 两种N肥施用水平。结果表明 ,CO2 浓度升高 ,冬小麦株高和叶面积指数 (LAI)均增加 ,净同化率 (NAR)值增加 ,叶面积比率 (LAR)下降 ,比叶重 (SLW )不增加。高CO2 浓度对相对生长率 (RGR)的影响因施N水平而异 ,低N时RGR不增加 ,高N时明显增加。CO2 浓度增加 ,小麦抽穗提早 7～ 8d ,叶鞘、茎杆和地上部干物重提高 ,叶片、叶鞘和茎杆N、P浓度降低 ,但叶片、叶鞘和茎杆N、P吸收量增加均不明显。CO2 浓度升高 ,氮磷利用效率 (NUE和PUE)提高 ,而对相对氮磷累积速率 (RNAR和RPAR)影响不大。高CO2 浓度冬小麦体内N、P浓度下降是由于稀释效应以及NUE和PUE提高之故。

INFLUENCE OF CO2 ENRICHMENT ON GROWTH OF AND N AND P CONCENTRATIONS IN WINTER WHEAT UNDER TWO N LEVELS

Atmospheric CO₂ levels are expected to exceed 700 L mol mol^-1 by the end of 21st century.Therefore the influence of increased CO₂ concentration on crop plants is of major concern.This study is an analysis of growth of and N and P concentrations in winter wheat(Triticum aestivum L.cv.Xinong 8727) grown under two levels of atmospheric CO₂ concentration(350 L mol mol^-1 and 700 Lmol mol^-1)and of nitrogen fert ilizer(45 kg hm^-2 and 90 kg hm^-2).Results showed that plant height,leaf area index (LAI)and net assimilation rate(NAR)increased,while leaf area ratio(LAR)reduced and specific leaf weight(SLW)remained unchanged under the high atmospheric CO₂ concentration.The influence of CO₂ enrichment on relative growth rate(RGR)was dependent on N level.Higher CO₂ concentration increased RGR significantly in the high N treatment,but did not increase in the low N treatment.Tasseling of winter wheat advanced by 7~8 days and masses of leaf sheaths,stalks and shoots also increased with CO₂ concentration increasing.Higher CO₂ decreased N and P concentrations in leaves,leaf sheaths and stalks, however it increased N uptake by winter wheat slightly.Higher CO₂ concentration increased use efficiencies of N and P(NUE and PUE),but did not affect relative nitrogen and phosphorus accumulation rates (RNAR and RPAR).Dilution of N and P due to increased dry mass and the enhancement of the use efficiencies of N and P can explain the decline in plant N content in the present experiment.