沙木蓼和沙枣对地下水位变化的生理生态响应Ⅰ.叶片养分、叶绿素、可溶性糖和淀粉的变化

ECOPHYSIOLOGICAL RESPONSES OF TWO XEROPHYTES ATRAPHAXIS FRUTESCENS AND ELAEAGNUS ANGUSTIFOLIA TO THE CHANGE OF GROUNDWATER DEPTH IN ARID AREA Ⅰ. CHANGES IN LEAF NUTRIENT, CHLOROPHYLL, SOLUBLE SUGAR AND STARCH CONTENTS

在甘肃民勤沙生植物园内利用植物蒸腾耗水量观测场 ,研究了两种优势旱生植物沙木蓼 (Atraphaxisfrutes cens)和沙枣 (Elaeagnusangustifolia)叶片中的叶绿素、可溶性糖、淀粉和N、P、K含量等对不同地下水深度 (1～ 3 .4m)的响应。结果表明 :1 ) 1 .4m、2 .4m和 3 .4m 3种不同的地下水深度处理 ,产生了 3种差异显著的土壤水分梯度 ;2 )地下水深度的变化导致了这两种旱生植物叶绿素a、叶绿素b、叶绿素总量、叶绿素a与叶绿素b的比值等的显著变化 (p <0 .0 1 ) ;3)地下水深度的增加引起了两种植物叶片可溶性糖含量的升高和淀粉含量的降低 ;4)地下水深度的增加引起了两种植物叶片中N、P、K含量的降低 ;5)不同的地下水深度引起沙枣和沙木蓼叶绿素a、叶绿素b、叶绿素总量、叶绿素a与叶绿素b的比值、N、P、K含量、可溶性糖和淀粉增加或减少的程度不同。沙枣是非豆科固氮植物 。

In order to elucidate the adaptation and ability of different xerophil ous plants to soil water availability and provide the theories of vegetation reg eneration for western desert areas in China, the photosynthetic physio_ecologica l characteristics and the contents of leaf chlorophyll, soluble sugar, starch, n itrogen, phosphorus and kalium of two desert plants (Atraphaxis frutescens a n d Elaeagnus angustifolia in response to ground water availability were inves tigated in a controlled environment at the Plant Transpiration Consume Water Observation Station in Minqin Desert Botanical Garden, Gansu province. In this experiment, the depths of groundwater (DGW) were set at three levels: 1. 4 m, 2.4 m and 3.4 m. In each treatment, the two desert plants were transplanted to the observation sites with different DGW after growing naturally for 3 or 4 yea rs. The contents of leaf chlorophyll, soluble sugar, starch, nitrogen, phosphoru s and kalium of the two desert plants were measured by the methods described in 'Experimental manual of plant physiology' and the photosynthetic measurements we re conducted by using an open gas_exchange system (LI_6400P, LI_COR Inc. Lincoln , NE,USA). The results showed that: 1) the three different DGW treatments resulted in a mar ked soil moisture gradient; 2) The changes of DGW led to significant changes in the leaf content of chlorophyll a (Chl a), chlorophyll b (Chl b), total chloroph yll (Chl a+Chl b) and the ratio of Chl a to Chl b (Chl a/Chl b) (p<0.01); 3) T he increment of DGW depths caused the increase of soluble sugar content and the decrease of starch content irrespective of plant species, but the extent of thes e changes varied between the two species; 4) Increased DGW caused a decrease in the content of nitrogen, phosphorus and kalium; 5) The changes of either increas e or decrease in chlorophyll a, chlorophyll b, total chlorophyll, nitrogen, phos phorus, kalium, soluble sugar, starch and the ratio of Chl a and Chl b of A. f rutescens and E. angustifolia varied with DGW. The original conclusions were drawn as follows: compared with A. frutescens, E . angustifolia may be more adaptive to the dry desert environmen t. Since E. angustifolia is a nitrogen_fixing species, further studie s are ne eded to verify whether the differences between these two species are related to nitrogen fixation.