【作者】 雍小华；

【导师】 贾志宽；

【作者基本信息】 西北农林科技大学 ， 生态学， 2009， 硕士

【摘要】 本研究通过对紫花苜蓿(Medicago Sativa)不同土层深度(40~500cm)断根处理后的生长发育和光合特性等指标进行了测定。主要研究结果如下:1.断根使紫花苜蓿株高降低、叶面积减小、茎变细、叶片数减少、产量降低,节间数和茎叶比分别呈减少、增加的趋势,鲜干比无显著变化。不同断根深度处理比较发现,浅层处理(≤80cm)和深层处理(≥360cm)紫花苜蓿植株较高、叶面积较大、茎较粗、节间数较多、茎叶比较小,中间层(120～320cm)处理则相反,此规律在断根后第二年尤为明显;断根后第二年第二茬及以后各茬,浅层处理(≤80cm)叶片数和对照无显著差异,而大于120cm的各处理叶片数显著减少;浅层处理(≤80cm)产量最高,深层处理(≥360cm)次之,中间层(120cm～320cm)处理最低。2.不同深度断根苜蓿的光合特性:断根后第一年,与未断根苜蓿相比,各断根处理花期光合速率(Pn)均增大, 200cm断根的细胞间隙CO2浓度(Ci)最大, 360cm断根的Ci达到最小,差异达极显著水平(P<0.01),各处理蒸腾速率(Tr)均呈现降低的趋势,水分利用效率(WUE)呈现为升高的趋势。第二年,与未断根苜蓿相比,除120cm和160cm处理外其它断根处理Pn均有不同程度的升高,40cm-200cm断根处理(除120cm外)无显著差异,500cm断根处理Pn最高;各断根处理气孔导度(Gs)均显著降低(P<0.05);各处理的Ci均降低,且除40cm与80cm断根处理外其它各处理差异均达显著水平(P<0.05);各断根处理的Tr均降低;500cm断根的苜蓿WUE最高,达极显著性差异(P<0.01),深层次处理(320cm-500cm)WUE较高。更多还原

【Abstract】 The growth and photosynthetic indexes of alfalfa under root pruning of different soil depths are measured in this study. The main results are as follows:1. The alfalfa height reduced, leaf area decreased, stem became thinner, leaf number reduced, and yield decreased after root pruning. Node number decreased and stem-leaf ratio increased, and the ratio of fresh weight and dry weight had no significant change. Comparison of different cutting depths treatments, it can be found that the alfalfa had higher plant height, larger leaves, thick stem, more node number, and stem-leaf ratio and leaf under shallow treatment (≤80cm) and deep treatment (≥360cm). But the middle treatment (120cm ~ 320cm) had the opposite result, especially evident in the second year. Compared with the control treatment, leaf number of the second and subsequent crop after root pruning under shallow treatment (≤80cm) had no significant differences, but under the treatment leaf number reduced significantly greater than 120cm. The yield of alfalfa was highest under shallow treatment (≤80cm), deep treatment (≥360cm) took the second place, and middle treatment the lowest.2. The photosynthetic characteristics of alfalfa after root pruning at different depths were as follows: in the first year of root pruning, compared with the non-cutting alfalfa, the florescence photosynthetic rate (Pn) of each root pruning treatment was increasing, CO2 concentration in the cell space (Ci) at the depth of 200cm of root pruning was largest but smallest at 360cm, and the difference reached a very significant levels (P <0.01). The Transpiration rate (Tr) of all treatments decreased, but the water use efficiency (WUE) increased. In the second year, compared with the non-cutting alfalfa,the Pn of all treatments increased at different degrees except the root pruning treatments at 120cm and 160cm, the difference was not significant from 40cm to 200cm except at 120cm, and the Pn of the treatment at 500cm is the highest. The stomatal conductance (Gs) of all root pruning treatments decreased significantly (P <0.05). The Ci of all treatments decreased, and differences were significant except of the treatments at 40cm and 80cm (P <0.05). The Tr of all treatments decreased. The WUE of alfalfa with 500cm root pruning was the highest, the difference was very significant (P <0.01), and The WUE of deep-level treatment was higher(320cm-500cm).更多还原