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71.
Cold acclimation of winter and spring peas: carbon partitioning as affected by light intensity 总被引:4,自引:0,他引:4
Virginie Bourion Isabelle Lejeune-Hnaut Nathalie Munier-Jolain Christophe Salon 《European Journal of Agronomy》2003,19(4):535-548
Like most plants, pea (Pisum sativum L.) becomes tolerant to frost if it is first exposed to low non-freezing temperatures, a process known as cold acclimation. Cold acclimation is a complex process involving many physiological and metabolic changes. Two spring dry peas, two winter dry peas and one winter forage line were exposed to cold temperature in a controlled environment in two experiments, one using low light intensity and the other regular light intensity. Plants were harvested throughout the experiment and dry matter accumulation, water content, soluble and insoluble sugar concentrations were determined from shoot and root samples. Cold acclimation did not occur when temperatures were low if light intensity was low, even in winter peas. In contrast, with regular light intensity, the winter peas acquired more freezing tolerance than spring peas and a close relationship was found between the soluble sugar concentration of leaves just before the frost and the degree of freezing tolerance obtained by the different genotypes. Relationships between freezing tolerance and carbon partitioning between shoot and roots are discussed. 相似文献
72.
镉对小麦幼苗的生长和生理生化反应的影响 总被引:45,自引:0,他引:45
镉对小麦幼苗和根系生长有抑制作用,尤以对根系的抑制更为显著,但镉浓度为5ppm时,有刺激生长的作用.幼苗的脯氨酸和可溶性蛋白质含量随镉浓度的增加而增加,尤其在高浓度镉下脯氨酸含量剧增,电解质外渗率也明显增大.镉使胚乳中的α-淀粉酶活性降低,这种效应随镉浓度增高而加强,随幼苗的生长却趋于减弱.镉诱导根的正、负极向过氧化物酶同工酶产生新谱带,并使原有的一些谱带活性增强.上述结果显示出镉使小麦幼苗的细胞结构和功能受到损害,而小麦幼苗对镉害也表现出一定的适应性保护反应. 相似文献
73.
外源C_4作物DNA导入小麦的研究 总被引:21,自引:1,他引:21
利用小麦自交后的花粉管通道,将C_4作物玉米或高粱的DNA导入小麦的种胚细胞,结果受体后代发生了广泛的变异,而且受体不同,所发生的变异不同。甘麦8号受体后代植株变矮,结实率低,分蘖多至5个,少至完全不分蘖;8347—2-4和8013—3品系后代中出现不育株;6873—20—3品系受体后代的籽粒由红色转变为白色而且稳定遗传;蓝粒麦受体后 相似文献
74.
75.
76.
Summary Cellulases in forest litter and soil occur in both bound and extractable forms. The proportion of total bound endocellulase activity (not extractable) increases during decomposition, whereas the proportion of bound exocellulase activity remains fairly constant. The proportions of bound enzymes differ among litter types with different chemical compositions. The proportion of bound activity is higher in mineral soil than in litter. We also investigated the effects of anion type (NaCl versus Na2SO4), concentration and pH on the extractability of cellulases and protein in two horizons of two forest soils. The extractability of cellulases increases as pH increases from 3.5 to 5.6. Anion type and concentration did not have consistent effects on extractability. However, there was a trend for higher extractability by sulfate than by chloride and with increasing salinity. 相似文献
77.
78.
Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006-0.025 mg/L for SRP and 0.057-0.176 mg/L for TP. For large storms (>6 cm bulk precipitation), for which macropore flow represented between 43 and 50% of total tile-drain flow, SRP transport to tile-drains was primarily regulated by macropore flow. For smaller tile-flow generating events (<3 cm bulk precipitation), for which macropore flow only accounted for 11-17% of total tile-drain flow, SRP transport was primarily regulated by matrix flow. Total P transport to tile-drains was primarily regulated by macropore flow regardless of the storm. Soluble reactive P (0.01-1.83 mg m−2/storm) and TP (0.10-8.64 mg m−2/storm) export rates were extremely variable and positively significantly correlated to both mean discharge and bulk precipitation. Soluble reactive P accounted for 9.9-15.5% of TP fluxes for small tile-flow generating events (<3 cm bulk precipitation) and for 16.2-22.0% of TP fluxes for large precipitation events (>6 cm bulk precipitation). Although significant variations in tile-flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of macropore flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management. 相似文献
79.
80.
光照条件对参株碳水化合物和人参皂甙含量的影响 总被引:6,自引:2,他引:6
本试验测定了5%,20%,35%和50%4种透光棚下人参植株各器官可溶性糖,淀粉和参根皂甙含量的变化。主要结果是:不同光强下人参植株各器官可溶性糖含量无明显差异,淀粉含量则随着光强和增加而增加,在5%和20%透光棚下,参根皂甙含量随着淀粉含量的增加而增加,并达到最大值;在35%和50%透光棚下,参根皂甙含量则随着淀粉含量的增加而下降。参根淀粉含量与参根干重呈显著正相关。 相似文献