黄土高原旱塬区3种堇菜属植物光合特性分析

Analysis on Photosynthetic Characteristics of Three Species of Viola Plants in the Dryland Area of the Loess Plateau

黄土高原旱塬区3种堇菜属植物分布状况、种群数量以及长势不同,为了探究堇菜属植物对光照强度和干旱生境的光合特性响应策略,试验通过测定同一生境下3种堇菜属植物以及紫花地丁在不同生境(田间、路边、荒地和林下)下的光合特性,比较净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、光能利用效率(LUE)及水分利用效率(WUE)等光合指标差异性,判断3种堇菜属植物在同一生境下光合特性的差异,分析紫花地丁光合特性与生态因子的相关性。结果表明,同一生境下3种堇菜属植物整个生长周期的净光合速率大小依次为紫花地丁>斑叶堇菜>早开堇菜;紫花地丁在4种生境条件下净光合速率大小依次为田间>路边>荒地>林下,生态因子光合有效辐射(PAR)、叶面温度(Tleaf)、土壤含水量(SMC)与光合参数Pn、Tr均呈正相关,与Gs、LUE、WUE均呈负相关。在路边干旱无遮挡的生境下,3种堇菜中紫花地丁适应性更强,光照强度是限制黄土高原旱塬区堇菜属植物分布的重要因素;最适宜紫花地丁生长的生境为田间,适度遮阴能够打破其“光合午休”现象,使其具有更大的光合作用潜力及更强的生态适应性。

The distribution,population number,and growth of three species of Viola plants in the dryland area of the Loess Plateau were different,and in order to explore the response strategy of the photosynthetic characteristics of Viola plants to light intensity and arid habitats,in this study,by measuring the photosynthetic characteristics of three Viola plants in the same habitat and the photosynthetic characteristics of Viola philippica in different habitats(field,roadside,wasteland,and forest),the differences in photosynthetic indexes such as net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductivity(Gs),light energy utilization efficiency(LUE),and water use efficiency(WUE)were compared,the differences of photosynthetic characteristics of the three Viola plants in the same habitat were judged,and the correlation between the photosynthetic characteristics of Viola philippica and ecological factors was analyzed.The results showed that the order of the net photosynthetic rate of the three Viola plants in the same habitat throughout the growth cycle was as follows:Viola philippica>Viola variegata>Viola prionantha.Under the conditions of four habitats,the order of Pn of Viola philippica was in the field>roadside>wasteland>forest,and the ecological factors including photosynthetically active radiation(PAR),leaf temperature(Tleaf),soil moisture content(SMC)were positively correlated with the photosynthetic parameters Pn and Tr,and were negatively correlated with Gs,LUE,and WUE.Viola philippica in the three kinds of Viola was more suitable for roadside drought and unobstructed habitats,and light intensity was an important factor limiting the distribution of Viola plants in the dryland area of the Loess Plateau.The most suitable habitat for the growth of Viola philippica was the field,and moderate shade could break its phenomenon of"photosynthetic lunch break",so that it had greater photosynthetic potential and stronger ecological adaptability.