植物生态学报 ›› 2012, Vol. 36 ›› Issue (1): 72-80.DOI: 10.3724/SP.J.1258.2012.00072

• 研究论文 • 上一篇    下一篇

水分对苜蓿叶片光合特性的影响

孙东宝1, 王庆锁*()   

  1. 中国农业科学院农业环境与可持续发展研究所, 农业部旱作节水农业重点开放实验室, 北京 100081
  • 收稿日期:2011-04-18 接受日期:2011-10-17 出版日期:2012-04-18 发布日期:2012-01-05
  • 通讯作者: 王庆锁
  • 作者简介:*(E-mail: wang-qingsuo@ieda.org.cn)

Effects of water on the photosynthetic characteristics of alfalfa (Medicago sativa)

SUN Dong-Bao1, WANG Qing-Suo*()   

  1. Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Dry Land Agriculture of Ministry of Agriculture, Beijing 100081, China
  • Received:2011-04-18 Accepted:2011-10-17 Online:2012-04-18 Published:2012-01-05
  • Contact: WANG Qing-Suo

摘要:

采用田间试验, 对每茬灌水3次(W3)、2次(W2)、1次(W1)和不灌水(W0)四种条件下的土壤水分, 苜蓿(Medicago sativa)叶片的叶绿素荧光参数、气孔导度(Gs)、净光合速率(Pn)和蒸腾速率(Tr)进行测定。结果表明, 灌水提高了苜蓿叶片的原初光能转换效率(Fv/Fm)、PnTr, 并随着灌水量的增加而增加。苜蓿叶片的Fv/FmPnTr的日均值与土壤含水量均呈极显著正相关关系。苜蓿叶片的PnFv/Fm和光合有效辐射(PAR)的乘积呈正相关关系。灌水还改变了苜蓿叶片Pn的日变化格局。灌水较多的处理(W3和W2), 苜蓿叶片没有出现光合“午休”现象,Pn的日变化趋势呈现“单峰”型。而灌水较少和不灌水的处理(W1和W0), 苜蓿叶片出现了明显的光合“午休”现象, 其Pn的日变化进程呈现“双峰”型。在相同的水分条件下, 初花期苜蓿叶片的Pn高于再生期的, Tr则相反。

关键词: 灌水量, 苜蓿, 原初光能转换效率, 光合速率, 蒸腾速率

Abstract:

Aims Alfalfa (Medicago sativa) is the most extensive perennial leguminous forage. In the semi-arid region, water is the most important limiting factor for alfalfa growth. Our objective was to study the effect of soil water content on physiological properties of alfalfa.
Methods Our field experiment consisted of four treatments: non-irrigation (W0) and irrigated (75 mm each) once (W1), twice (W2) and three times (W3) for each crop. We evaluated soil moisture, leaf chlorophyll fluorescence parameters, stomatal conductance (Gs), transpiration rate (Tr), and net photosynthetic rate (Pn).
Important findings The original light conversion efficiency (Fv/Fm), Gs, Tr, and Pn of alfalfa were significantly improved by increasing irrigation. Moreover, correlation analysis showed that the mean value of the day of Fv/Fm, Gs, Tr, and Pn had significantly positive relationships with the average soil water content of 0-280 cm depth. Pn had a significantly positive relationship with Fv/Fm × PAR (photosynthetically active radiation). Additional irrigation also changed the diurnal courses of leaf Pn. Photosynthesis of alfalfa under W2 and W3 treatments did not present the “midday depression”, and the diurnal courses were unimodal. Nevertheless, treatments W 1 and W0 exhibited an apparent “midday depression” phenomenon, and the diurnal variation was bimodal. There were different physiologically activities at different growth stages of alfalfa. Pn of alfalfa in the early flowering stage was obviously higher than in the regeneration stage, in contrast Tr was lower at the early flowering stage.

Key words: irrigation amount, Medicago sativa, original light conversion efficiency, photosynthesis rate, transpiration rate