缺氮和复氮对菘蓝幼苗生长及氮代谢的影响

对基质育苗后水培的菘蓝进行缺氮与复氮处理,分析其生长情况及氮代谢产物含量的变化,探讨缺氮和复氮对菘蓝幼苗生长及氮代谢的影响,以提高菘蓝产量和品质以及栽培过程中的氮素利用效率。结果显示:(1)正常供氮条件下,菘蓝幼苗的叶绿素含量、谷氨酰胺合成酶(GS)活性、硝态氮含量、靛玉红含量为最高,而其株高、主根直径、根的鲜重与干重、叶的鲜重与干重、根系活力均最小。(2)缺氮处理增加了菘蓝幼苗的主根直径和根干重,提高其根系活力和硝酸还原酶(NR)活性,促进游离氨基酸在叶中的积累;但降低了GS的活性,也降低了叶中硝态氮、可溶性蛋白、靛玉红及根中游离氨基酸的含量;缺氮对叶中靛蓝的含量无明显影响。(3)复氮处理增加了菘蓝幼苗的株高、主根长、根鲜重、叶鲜重、叶干重,提高了其根系活力,降低了NR和GS的活性;与对照相比,复氮降低了叶中硝态氮含量,提高了叶中可溶性蛋白、靛蓝及根中游离氨基酸的含量,但对叶中游离氨基酸和靛玉红含量影响较小。研究表明,缺氮后再复氮有利于菘蓝幼苗叶的生长,同时有利于增加其叶内靛蓝含量,从而提高其产量和品质。     

Short-term impacts of enhanced UV-B radiation on photo-assimilate allocation and metabolism: a possible interpretation for time-dependent inhibition of growth

To test the hypothesis that plant source-sink relations are important in determining response to UV-B radiation, a short-term (45 d) field experiment was conducted at Abisko Scientific Research Station, Abisko, Sweden (68° N). Tillers of the grass Calamagrostis purpurea were grown outdoors at levels of UV-B radiation representing 25% ozone depletion. Growth, respiration, photo-assimilate allocation and UV-B protective compounds were subsequently measured.There were no significant effects of enhanced UV-B on total plant dry weight, leaf area, Shoot: Root ratio, leaf weight ratio, leaf area ratio, specific leaf area, tiller number per plant or blade thickness of this species. However, the amount of UV-B absorbing compounds and respiration rates were significantly increased in young and mature leaves. Increases in leaf respiration were accompanied by alterations in plant carbohydrate allocation at enhanced UV-B. The amount of soluble root carbohydrates was reduced following UV-B exposure. Enhanced UV-B also caused increases in the soluble sugar: starch ratio of young leaves, the stem and total aboveground biomass. The importance of source-sink relations and constitutive versus induced defense are discussed in relation to UV-B response.     

The effect of altered sink-source relations on photosynthetic traits and matter transport during the phase of reproductive growth in the annual herb <Emphasis Type="Italic">Chenopodium album</Emphasis>

Annual plants transport a large portion of carbohydrates and nitrogenous compounds from leaves to seeds during the phase of reproductive growth. This study aimed to clarify how reproductive growth affects photosynthetic traits in leaves and matter transport within the plant in the annual herb Chenopodium album L. Plants were grown in pots and either reproductive tissues or axillary leaves were removed at anthesis. Matter transport was evaluated as temporal changes in dry mass (as a substitute of carbohydrates) and nitrogen content of aboveground organs: leaves, axillary leaves, stems and reproductive tissues. Photosynthetic capacity (light-saturated photosynthetic rate under ambient CO₂ concentration), nitrogen, chlorophyll and soluble protein content were followed in the 20^th leaf that was mature at the start of the experiment. Removal of reproductive tissues resulted in accumulation of dry mass in leaves and axillary leaves, and accumulation of nitrogen in stem as nitrogen resorption from leaves and axillary leaves proceeded with time. Removal of axillary leaves proportionally reduced dry mass and nitrogen allocation to reproductive tissues, thus affecting the quantity but not quality of seeds. Removal treatments did not alter the time course of photosynthetic capacity, nitrogen, chlorophyll or soluble protein content during senescence in the 20^th leaf, but changed the photosynthetic capacity per unit of leaf nitrogen according to demand from reproductive tissues. Together, the results indicate that reproductive tissues affected carbon and nitrogen economy separately. The amount of carbon was adjusted in leaves through photosynthetic capacity and carbohydrate export from them, and the amount of nitrogen was adjusted by transport from stem to reproductive tissues. The plant’s ability to independently regulate carbon and nitrogen economy should be important in natural habitats where the plant carbon-nitrogen balance can easily be disturbed by external factors.     

Chemical composition of leaves and structure of photosynthetic apparatus in aquatic higher plants

Chemical composition of leaves (the content of carbon, nitrogen, nonstructural carbohydrates, organic acids, mineral substances, and water) and the structure of photosynthetic apparatus (specific leaf weight, cell volume, and the number of cells per unit leaf area) were investigated for 18 species of aquatic plants featuring various degrees of contact with aqueous environment and sediment. The rooted hydrophytes with floating leaves were characterized by comparatively high content of carbon and nitrogen (437 and 37 mg/g dry wt, respectively) and by low concentration of nonstructural carbohydrates, mineral substances, and organic acids (161, 54, and 60 mg/g dry wt, respectively). Unlike rooted plants, the free-floating nonrooted hydrophytes had characteristically higher content of nonstructural polysaccharides and mineral substances (by a factor of 1.3 and 1.6, respectively), while the leaf nitrogen content was 1.4 times lower, and the proportion of soluble carbohydrates in the total content of nonstructural carbohydrates was rather low (9%). The chemical composition of leaves in submerged rooted hydrophytes was intermediate between those for rooted hydrophytes with floating leaves and for nonrooted free plants. We found reliable positive correlations between the volume of photosynthesizing cells and the leaf content of organic acids (r = 0.69), as well as between specific leaf weight, the number of photosynthesizing cells per unit leaf area, and carbon content (r = 0.67 and r = 0.62, respectively). The content of nitrogen and nonstructural carbohydrates in hydrophytes was unrelated to structural characteristics of photosynthetic apparatus and depended on the absence or presence of plant attachment to the sediment. It is concluded that the structural traits of photosynthetic apparatus and the leaf chemical composition in hydrophytes featuring different degrees of plant contact with water and sediment reflect the specificity of plant adaptation to complex conditions of their habitats.     

Increased chilling tolerance and altered carbon metabolism in tomato leaves following application of mechanical stress

We investigated the effects of brushing on the chilling tolerance and metabolism of nonstructural carbohydrates (soluble sugars and starch) in tomato leaves before, during and after a chilling stress. Tomato plants ( Lycopersicon esculentum Mill. cv. Caruso) were cultivated either without mechanical stress application (control plants) or with daily brushing treatments for 15 days (brushed plants), prior to a 7-day chilling treatment (8/5°C day/night). Brushing resulted in shorter plants with a 34% reduction in leaf dry weight per area and a 59% reduction of soluble sugars and starch, on a dry weight basis. The sugar to starch ratio was not affected by brushing. A greater chilling tolerance in the brushed plants was demonstrated by the maintenance of a significantly higher PSII efficiency in brushed plants (42%) compared to that of the control plants (30%) after 7 days of chilling treatment, less visible damage to the leaf tissue, and a more rapid resumption of growth during 3 days of recovery as compared to control plants. During the chilling treatment levels of soluble sugars per leaf dry weight increased 15-fold in the brushed plants and 5-fold in control plants. In the present study we have demonstrated that brushing can increase chilling tolerance in tomato plants. The observed differences in chilling tolerance and concentration of soluble sugars in the leaves may indicate an involvement of soluble sugar levels in acclimation to chilling.     

Some biochemical changes during leaf rolling in Ctenanthe setosa (Marantaceae)

The changes in the levels of proline, sugar and soluble protein during leaf rolling and its relationship to osmotic adjustment were studied in laboratory conditions. Upon irrigation of plants which have rolled leaves, many sugar crystals occurred on the abaxial surface of the leaves in Ctenanthe setosa (Rosc.) Eichler. The sugar crystals were determined to have sucrose, glucose and fructose. The levels of reducing sugars and proline are higher in rolled leaves while soluble protein levels in rolled leaves are lower than those of unrolled leaves. It was found 1–3, 9–13, 16–21 and 24–28 crystals at degree of leaf rolling 23, 28, 47 and 52%, respectively. Finally, we found a significant correlation between the crystal number and degree of leaf rolling in Ctenanthe setosa. In addition, soluble sugars are found predominant accumulating solute in the plant and are of major importance as a contributor to osmotic adjustment during leaf rolling.     

MORPHOLOGY OF MARSILEA VESTITA. III. MORPHOGENESIS OF THE LEAVES OF ETIOLATED PLANTS

The laminae of etiolated Marsilea vestita leaves develop by means of marginal meristems. Unlike light-grown plants, the form of the etiolated plant is not affected by growth on a solid medium. All of the young leaves isolated from light-grown submerged plants will elongate in darkness. The smallest, etiolated, uncoiled leaves develop into land leaves when they are placed in light, and this development occurs regardless of whether the leaves remain on the plant or are isolated on nutrient agar. Only these smallest leaves (2.3 mm average length) are actually capable of being converted from a submerged leaf form to a land leaf form by darkness.     

Biochemical Changes in Excised Leaves of Oryza sativa Subjected to Water Stress

Excised rice (Oryza sativa L. cv. Ratna) leaves were used to compare the changes in the levels of various biochemical intermediates and enzyme activities during senescence in turgid and water-stressed conditions. Chlorophyll, total protein and soluble protein content decreased but α-amino nitrogen content increased during the senescence of turgid leaves. In the leaves subjected to water stress, these changes were accelerated, the acceleration being greater with higher degree of water stress. Starch, soluble sugars, total carbohydrates and non-reducing sugar content decreased during senescence of turgid leaves. Water stress accelerated the changes in the levels of starch and non-reducing sugar, but the changes in the levels of soluble sugars and total carbohydrates were retarded. Reducing sugar content increased at first and then decreased in the turgid leaves, and water stress accelerated the change. The decline in the catalase activity and the increase in the peroxidase activity with time was faster in the water-stressed leaves than in the turgid leaves. Acid inorganic pyrophosphatase activity increased, but alkaline inorganic pyrophosphatase activity decreased during the senescence of turgid leaves, and such changes were accelerated by water stress. The results suggest that water stress does not accelerate all the processes connected with leaf senescence.     

Soybean leaf responses to threecornered alfalfa hopper petiole girdling

Specific leaf weight, percent moisture, and free sugar, starch, and amino nitrogen content of soybean (Glycine max (L.) Merrill) leaves were measured at 1, 3, 7, and 10 day(s) after petiole girdling by threecornered alfalfa hopper,Spissistilus festinus (Say) (Homoptera: Membracidae) nymphs. Leaf starch was increased at 1, 3, and 7 day(s) after girdling and largely accounted for corresponding increases in specific leaf weight and decreases in percent moisture, free sugars, and amino nitrogen. Specific leaf weight was increased at 10 days after girdling despite no increase in starch. Amino nitrogen content was decreased 10 days after girdling. When leaf dry weights were corrected for starch, free sugar content was not affected by girdling, and amino nitrogen content was reduced only at 3 and 10 days. The amino nitrogen: free sugar ratio was reduced only at 10 days after girdling. Changes in leaf starch indicated a rapid but reversible effect of girdling on leaf carbohydrate metabolism.     

DEVELOPMENTAL CHANGES IN ENERGY (ATP AND ADP) AND NUTRIENT LEVELS PRIOR TO SENESCENCE IN PODDED AND DEPODDED PEA PLANTS

Energy (ATP and ADP) levels in stem apices of depodded pea plants (Pisum sativum L. cv. Little Marvel) were significantly higher than those of podded plants during the pod-filling stage before whole plant senescence. This difference in energy content appeared before decreases in leaf chlorophyll and soluble proteins occurred in plants of both treatments. In contrast, the mineral nutrient levels (N, P, K, Ca, Mg, Fe, and Mn) in stem apices of plants from both treatments were similar. Energy levels in reproductive leaves from podded and depodded plants were similar. The mineral nutrients in leaves with fruits in their axils and similar leaves of depodded plants were comparable except for nitrogen. Plant growth measurements—dry weight, leaf area, leaf dry weight, root/shoot ratio—were significantly higher in depodded than podded plants. Whole plant senescence occurred significantly earlier in podded than in depodded pea plants.     

Responses of Penultimate and Flag Leaves of Wheat to Different Nitrogen Supply

Uniculm wheat (Triticum aestivum L.) was grown to maturity at four concentrations of nitrogen corresponding to 3 (N1), 6 (N2), 9 (N3) and 12 (N4) g m^–2. Penultimate and flag leaves were examined throughout the ontogeny. Sub-optimal concentrations of N resulted in sharp decline in both area and dry mass of the leaves. Decline in leaf area was due to fewer mesophyll cells. Net photosynthetic rate (P_N) increased up to full expansion, remained constant for about a week and then declined. P_N, nitrogen, ribulose-1,5-bis-phosphate carboxylase/oxygenase (RuBPCO) amount and activity, chlorophyll and soluble protein contents were similar at all the N concentrations. Both amount and activity of RuBPCO in the flag leaf were about two fold higher as compared to penultimate leaf, but P_N was similar. This indicates the presence of an excess amount of RuBPCO in the flag leaf.     

不同水分管理下优质稻花后植株碳氮流转与籽粒生长及品质的相关性

以桂华占、八桂香为材料,在干湿交替灌溉、亏缺灌溉、淹水灌溉3种水分条件下,研究优质稻花后植株碳氮流转与籽粒生长及品质的相关性。结果表明:不同水分管理下,桂华占和八桂香花后碳氮流转与籽粒的生长间存在密切相关。主要表现在:(1)茎鞘和叶片干物质转运对籽粒干物质积累的贡献率为16.86%～25.68%,花后茎叶干物质运转速度和运转率与籽粒起始灌浆势呈显著甚至极显著正相关;籽粒最大灌浆速率、活跃灌浆期、持续灌浆时间与叶片干物质运转速度和运转率呈极显著正相关,与茎鞘干物质运转速度和运转率呈极显著负相关;(2)茎鞘碳同化物转运对籽粒的产量和淀粉产量的贡献率则为干湿交替灌溉>亏缺灌溉>淹水灌溉;但叶片碳同化物转运对籽粒的产量和淀粉产量的贡献率则为淹水灌溉>亏缺灌溉>干湿交替灌溉;茎叶可溶性糖积累量的减少和籽粒直链淀粉含量和积累量增加是同步的,且茎叶可溶性糖积累量快速递减期(花后3～12d)与直链淀粉含量和积累量快速递增期(花后6～12d)同步;(3)茎鞘和叶片氮素转运对籽粒氮素积累的贡献率为44.05%～117.66%,叶片总氮转运对籽粒氮素积累的贡献率大于茎鞘,茎鞘和叶片氮同化物对籽粒氮素的贡献率以淹水灌溉处理的最大,亏缺灌溉处理的次之,干湿交替灌溉处理的最小。     

PP333对离体苹果苗的生长及其生理的影响

在生根培养基中加入0.5或2.0PPm PP333, 明显地减少了苹果离体新梢的鲜重和干重、叶片鲜重和叶面积,增加了比叶重、根的鲜重和干重及根梢鲜重和干重比,并促进了根的形成。PP333对单位叶重量的叶绿素含量没有影响,而增加了单位叶面积的叶绿素含量。经PP333处理后,叶片中的淀粉含量、过氧化物酶活性、蛋白质和游离氨基酸的含量均明显高于对照,可溶性糖与对照差异不明显。     

巴郎山大叶醉鱼草叶片非结构性碳水化合物和氮分配的海拔响应

为深入认识和探讨植物对环境变化的生理生态响应和适应,以分布在川西巴郎山的大叶醉鱼草(Buddleja davidii)为研究对象,沿海拔梯度对植物叶片中非结构性碳水化合物(NSC)、可溶性糖和淀粉含量,氮含量和氮分配比例(光合系统氮分配比例P_P、细胞壁氮分配比例P_CW和其他组分氮分配比例P_other)等参数进行对比分析,探讨其沿海拔的变化趋势,以及叶片NSC、可溶性糖和淀粉含量与氮分配间的相关关系。结果显示：大叶醉鱼草叶片NSC、可溶性糖、淀粉和单糖含量随海拔的升高而增加,而可溶性糖/淀粉比值未发生显著变化,表明高海拔较高的NSC含量的累积是由可溶性糖和淀粉含量共同决定的,而可溶性糖含量的增加主要由单糖含量的变化引起。叶片氮含量和P_P在海拔间差异不显著,但P_CW和P_other分别随海拔升高而降低和升高。此外,随海拔升高,叶片NSC/N比值随之增加,这主要归因于随海拔升高而增加的NSC含量而非海拔间差异不显著的氮含量。NSC含量和可溶性糖含量均与P_...     

Japanese oak silkmoth feeding preference for and performance on upper-crown and lower-crown leaves

We quantified differences in leaf traits between upper and lower crowns of a deciduous oak, Quercus acutissima, and examined feeding preference, consumption and performance of the Japanese oak silkmoth, Antheraea yamamai, for those leaves. Upper‐crown leaves had significantly smaller area, larger dry mass per area, greater thickness, lower water content, higher nitrogen content and a higher N/C ratio than lower‐crown leaves. When simultaneously offered upper‐crown and lower‐crown leaves, moth larvae consumed a significantly larger amount of the former. However, when fed with either upper‐crown or lower‐crown leaves (no choice), they consumed a significantly larger amount of the latter. Female larvae reared on upper‐crown leaves had a significantly smaller fresh weight, but attained a significantly larger pupal fresh and dry weight, with a significantly higher relative growth rate than those on lower‐crown leaves. Although, like female larvae, male larvae had a significantly smaller fresh weight when reared on upper‐crown leaves, they had a significantly larger value only for pupal dry weight. These results suggest that: (i) larvae ingest a greater amount of lower‐crown leaves to compensate for the lower nitrogen content of the foliage, resulting in having an excess of water because of the higher water content of the foliage; (ii) feeding preference for upper‐crown leaves accords with better performance (with respect to dry pupal weight and relative growth rate) on the foliage; (iii) better performance is explained by a higher nitrogen content and N/C ratio of the upper‐crown foliage; and (iv) the effects of leaf quality on performance differ between sexes.     

PP_(333)对离体苹果苗的生长及其生理的影响

在生根焙养基中加入0.5或2.0ppm PP_333,明显地减少了苹果离体新梢的鲜重和干重、叶片鲜重和叶面积,增加了比叶重、根的鲜重和干重及根梢鲜重和干重比,并促进了根的形成。PP_333对单位叶重量的叶绿素含最没有影响,而增加了单位叶面积的叶绿素含量。经PP_333处理后,叶片中的淀粉含量、过氧化物酶活性、蛋白质和游离氨基酸的含量均明显离于对照,可溶性糖与对照差异不明显。     

Seasonal distribution and changes in the nutritive quality of living,dead and detrital fractions of Zostera marina L.

Samples of eelgrass, Zostera marina L., were collected monthly from December 1974 through December 1975 in a shallow embayment near Beaufort, N.C., and separated into green leaves, dead leaves, and leaf detrital material. Each component was analysed for dry weight, organic matter, inorganic and organic carbon, nitrogen and amino compounds.The standing crop of green and dead blades reached a maximum in April through June, while detrital matter had peaks in December, April and July–September. Inorganic carbon in the three grass fractions showed seasonal variations similar to those observed for epiphytic biomass in previous years, and represented 14, 24, and 30% of the total carbon associated with the green and dead leaves and detrital fragments, respectively. Organic carbon represented a decreasing proportion of the dry weight of these three fractions on a dry weight basis while there was a significant increase in organic carbon on an ash-free dry weight basis in the detrital fragments relative to the head dead blades. During senescence there was a loss of nitrogen from the leaves and an increase in the nitrogen content of the organic matter of the detritus relative to the dead leaves. The latter suggests that there was microbial growth on the detritus and subsequent nitrogen immobilization from the surrounding medium. There were significant decreases of lysine, histidine, arginine, glycine, tyrosine, and glucosamine in the dead leaves relative to the detritus. The glucosamine, derived from N-acetyl-glucosamine, a product of murein which is a component of microbial cell walls, had a seasonal distribution similar to that of the epiphytic community and available inorganic nitrogen in the surrounding water. The relative proportions of N-acetyl-glucosamine, nitrogen and organic carbon were all higher in the fall and winter.     

热带次生林不同林层植物叶片非结构性碳水化合物的季节变化及其对氮磷添加的响应

非结构性碳水化合物(Non-structural Carbohydrates, NSCs)是植物生长代谢过程中重要的能量来源。通过在华南热带次生林进行氮磷添加试验,探究不同林层植物叶片NSCs的季节变化及其对氮磷添加的响应,取样时间为2019年1月、4月、7月和10月。结果表明:1)植物叶片NSCs存在显著的种间差异,磷(P)添加对叶片淀粉和NSCs含量具有显著影响,且物种与磷添加的交互作用显著影响叶片淀粉含量。2)黑嘴蒲桃和紫玉盘叶片NSCs含量对氮(N)添加的响应较为敏感,而白车和竹节叶片NSCs含量对P添加的响应较为敏感,氮磷同时添加(+NP)对植物叶片NSCs的增效作用最好。3)植物叶片NSCs存在显著的季节性变化,且季节与林层间的交互作用对叶片可溶性糖和NSCs含量具有显著影响。4)不同林层植物对氮磷添加的响应不同,氮磷添加使林下层植物叶片可溶性糖含量增高,林冠层降低,在干季,N添加会使林下层植物叶片淀粉含量增高,林冠层降低。P添加的影响恰好与之相反。在湿季,氮磷添加使林下层和林冠层植物叶片的淀粉含量增加。5)林冠层植物叶片NSCs含量高于林下层,且林下层植物叶片NSCs含量...     

增铵营养对小麦光合作用及硝酸还原酶和谷氨酰胺合成酶的影响

采用水培试验研究不同形态氮营养(NH4^+／NO3^-分别为0／100、50／50和100／0)对小麦光合作用及氮代谢关键酶活性的影响．结果表明,增铵营养较单—NO₃^-营养显著提高叶片叶绿素含量、净光合速率及可溶性糖含量,叶、根中可溶性蛋白质含量和叶片硝酸还原酶活性。而对谷铵酰胺合成酶活性影响较小．与单—NO₃^-营养相比。增氨营养下叶片较高的可溶性糖含量与净光合速率的提高相关。而维持较高的叶片和根系可溶性糖／可溶性蛋白质比例有利于氮同化和生长．因此,增铵营养下提高了叶片净光合速率、可溶性糖含量和硝酸还原酶活性。维持较高叶片和根系可溶性糖／蛋白质比例。从而促进小麦生长．     

The effects of exogenous polyamines on some biochemical changes during drought stress in Ctenanthe setosa (Rosc.) Eichler

Morphological and biochemical changes in plant cells are known as important events for adaptation to stress. In this study, in Ctenanthe setosa leaves to which polyamines were applied during drought stress, changes in the activity of peroxidase, reducing sugar, proline and soluble protein levels were investigated. The three common polyamines, putrescine, spermidine and spermine were exogenously treated through the leaves. The polyamines were sprayed onto the leaves at 5 x 10(-5) M. In the leaves to which polyamines were applied the peroxidase activity decreased, soluble protein increased. Also, it was determined that putrescine and spermidine caused an increase in the amount of proline and in reducing sugar. However, increase was not observed in the leaves to which spermine was applied. In addition, we observed an increase in the activity of peroxidase, proline and reducing sugar levels, and a decrease in soluble protein level in the control ones and the leaves to which polyamines were applied during drought stress. As a result, the effect of polyamine on leaf rolling may be explained through the contribution to osmotic adjustment of the increase in proline, reducing sugar and soluble protein contents.