水分胁迫对冬小麦CO_2同化作用的影响

比较了两个小麦品种陕合6号和郑引1号经受不同程度的水分胁迫处理后,叶片多种光合参数:净光合速率(P_n)、气孔导度(G_s)、细胞间隙CO_2浓度(G_i)、表观量子需要量和羧化效率以及Rubis CO蛋白量与活性等的变化。在轻度水分胁迫下,叶片光合速率降低的根本原因在于气孔导度的下降;而在严重胁迫下,非气孔因素起主要作用。     

Effects of External Potassium Supply on Compartmentation and Flux Characteristics of Radiocaesium in Intact Spring Wheat Roots

Short term experiments investigated the effects of potassiumsupply on radiocaesium influx/efflux and the radiocaesium compartmentationin intact spring wheat roots. Short term (24–72 h) influxanalysis showed that net influxes of radiocaesium to both rootand xylem were reduced approximately ten-times by increasingexternal potassium concentration from 50 µM to 200 µM.Efflux analysis distinguished three components for radiocaesium(namely cell wall+free space, cytoplasm and vacuole) and showedthat the rates of Cs⁺efflux at an external potassium concentrationof 100 µM (19.16 and 1.70 Bq g^-1min^-1for     

Effects of External Potassium Supply on Compartmentation and Flux Characteristics of Radiocaesium in Intact Spring Wheat Roots

Originally published in Annals of Botany84: 639–644 1999.For technical reasons beyond our control the flux symbol wasomitted from this paper. The paper is reprinted here in itsentirety. Short term experiments investigated the effects of potassiumsupply on radiocaesium influx/efflux and the radiocaesium compartmentationin intact spring wheat roots. Short term (24–72 h) influxanalysis showed that net influxes of radiocaesium to both rootand xylem were reduced approximately ten-times by increasingexternal potassium concentration from 50 µM to 200 µM.Efflux analysis distinguished three components for radiocaesium(namely cell wall+free space, cytoplasm and vacuole) and showedthat the rates of Cs⁺efflux at an external potassium concentrationof 100 µM (19.16 and 1.70 Bq g^-1min^-1for _coand _vo, respectively)were about three-times faster than those at 50 µM (7.24and to 0.41 Bq g^-1min^-1for _coand _vo, respectively). The resultsalso showed that external potassium concentration did not havea significant effect on the distribution of¹³⁷Cs between cytoplasmand vacuole, as indicated by the ratio of¹³⁷Cs in the two compartments.Results obtained in this study suggested that the inhibitoryeffect of potassium on the net uptake of radiocaesium by theplant root may be partially ascribed to the fact that at higherexternal potassium concentrations Cs⁺efflux rates were muchhigher. The mechanisms involved are discussed. Copyright 2000Annals of Botany Company Compartmentation, efflux analysis, potassium, radiocaesium, Triticum aestivum, wheat.     

Ionic and Osmotic Effects of Salinity on Single-Leaf Photosynthesis in Two Wheat Cultivars with Different Drought Tolerance

The effects of iso-osmotic salinity and drought stresses on leaf net photosynthetic rate (P _N) in two wheat (Triticum aestivum L.) cultivars BR 8 and Norin 61, differing in drought tolerance, were compared. In drought-sensitive Norin 61, the decline of P _N was larger than that in drought-tolerant BR 8. Under NaCl treatment, P _N decreased in two phases similarly in both cultivars. In the first phase, photosynthetic depression was gradual without any photochemical changes. In the second phase, photosynthetic depression was rapid and accompanied with a decline of the energy conversion efficiency in photosystem 2 (_PS2). Our observations suggest that the osmotic factor may induce a gradual depression of photosynthesis due to stomatal closure under both stress treatments. However, under NaCl treatment, a ionic factor (uptake and accumulation of excess Na⁺) may have direct effects on electron transport and cause more severe photosynthetic depression. The drought tolerance mechanism of BR 8 was insufficient to maintain single-leaf photosynthesis under salinity.     

Leaf Gas Exchange and Fluorescence of Two Winter Wheat Varieties in Response to Drought Stress and Nitrogen Supply

Water and nitrogen supply are the two primary factors limiting productivity of wheat (Triticum aestivum L.). In our study, two winter wheat varieties, Xinong 979 and large-spike wheat, were evaluated for their physiological responses to different levels of nitrogen and water status during their seedling stage grown in a phytotron. Our results indicated that drought stress greatly reduced the net photosynthetic rate (P_n), transpiration rate (E), and stomatal conductance (G_s), but with a greater increase in instantaneous water use efficiency (WUE). At the meantime, the nitrogen (N) supply improved photosynthetic efficiency under water deficit. Parameters inferred from chlorophyll a measurements, i.e., photochemical quenching coefficient (qP), the maximum photochemical efficiency (F_v/F_m), the quantum yield of photosystemII(Φ_PSII), and the apparent photosynthetic electron transport rate (ETR) decreased under water stress at all nitrogen levels and declined in N-deficient plants. The root–shoot ratio (R/S) increased slightly with water stress at a low N level; the smallest root–shoot ratio was found at a high N level and moderate drought stress treatment. These results suggest that an appropriate nitrogen supply may be necessary to enhance drought resistance in wheat by improving photosynthetic efficiency and relieving photoinhibition under drought stress. However, an excessive N supply had no effect on drought resistance, which even showed an adverse effect on plant growth. Comparing the two cultivars, Xinong 979 has a stronger drought resistance compared with large-spike wheat under N deficiency.     

7个冬小麦品种灌浆期抗旱性鉴定指标的综合评价

采用7个冬小麦(Triticum aestivum L.)品种,研究了不同水分处理下部分生理指标和部分农艺性状变化,以各单项指标的抗旱系数作为抗旱性衡量指标,利用主成分分析对其抗旱性进行评价,同时将综合评价值(D值)与抗旱指数(DRI)进行相关性分析。结果表明:(1)与对照相比,干旱胁迫后的超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、相对电导率、丙二醛(MDA)含量、脯氨酸(Pro)含量、可溶性糖含量、胞间CO2浓度(Ci)均有不同程度上升;根系活力、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、株高、穗下节长度、叶面积、穗长、小穗数和穗粒数均下降;过氧化物酶(POD)活性和可溶性蛋白质含量在各品种间变化趋势不尽一致。(2)通过主成分分析综合评价值(D值),供试品种可分为3类:‘晋麦47’和‘小偃22’属于强抗旱型;‘矮抗58’、‘西农979’和‘西农509’属于中等抗旱型;‘郑麦366’和‘郑麦9023’属于弱抗旱型。(3)两种不同干旱胁迫下综合评价值(D值)与抗旱指数均显著相关(r分别为0.768和0.808,p0.05)。     

种植密度对两种穗型小麦品种分蘖期茎蘖生理特性的影响

选用分蘖成穗率不同的2种穗型冬小麦品种,通过3个密度水平大田试验研究了分蘖期主茎和不同蘖位分蘖间的干物质积累与光合特性的差异,以探讨2种穗型品种分蘖成穗的生理机制.结果显示:(1)在冬小麦分蘖期间,分蘖成穗率低的大穗型品种'兰考矮早八'高位分蘖干物质积累速率较慢,分蘖与主茎的差距较大;而分蘖成穗率高的多穗型品种'豫麦49-198'分蘖与主茎的干物质积累速率差距较小.(2)2品种分蘖与主茎干物重比值(蘖/茎)均随着种植密度增加而降低,成穗分蘖的蘖/茎值拔节期均大于0.5,而同期未成穗分蘖均低于0.5.(3)在分蘖期间,'兰考矮早八'分蘖的净光合速率随生育进程增长比主茎缓慢,且随密度增加分蘖与主茎的差距进一步加大;'豫麦49-198'分蘖与主茎的光合速率差异较小,且种植密度对其影响也较小.(4)拔节中前期种植密度对2品种的荧光参数影响较小,拔节后期2品种分蘖的初始荧光(F0)均显著大于主茎,而PSⅡ最大光化学效率(Fv/Fm)却显著低于主茎;随种植密度增加,2品种主茎与分蘖的F0和Fv/Fm差异增大,且这种趋势随蘖位上升表现得更加明显.研究表明,大穗型品种'兰考矮早八'拔节期主茎与分蘖间干物质积累和光合性能的差异过大是其分蘖成穗率低的主要原因.     

干旱胁迫下耐旱性小麦在不同生育期脱水素的表达分析

以2种耐旱性不同的盆栽小麦陕合6号(干旱耐受型)和郑引1号(干旱敏感型)为材料,分别在其苗期、分蘖期、拔节期、开花期对土壤实施不同程度的自然干旱胁迫和复水处理,采用SDS-PAGE和Western blotting技术研究其叶片脱水素的表达规律,探究小麦整个生长期脱水素的表达与干旱胁迫的关系.结果表明:2种小麦的脱水素均仅在干旱胁迫时表达,其中45 kD和37 kD的脱水素在2种小麦的4个发育期的叶片中均有表达,28 kD的脱水素仅在特定发育时期表达.在干旱耐受型小麦(陕合6号)中,脱水素在胁迫初期少量表达,随着胁迫程度加剧表达量急剧增加,在重度干旱胁迫下达到峰值,复水后小麦叶片中脱水素含量迅速下降;在干旱敏感型小麦(郑引1号)中,脱水素在胁迫初期大量表达,中度胁迫表达量小幅度回落,到复水1 d达到峰值,此后随着复水时间增加小麦叶片中脱水素的量逐渐下降.研究表明,小麦叶片脱水素表达与干旱胁迫程度和生育期迫密切相关,不同耐旱型小麦材料中叶片脱水素表达的差异与品种之间的干旱耐受能力密切相关.     

Lipid Composition and Protein Dynamics in Thylakoids of Two Wheat Cultivars Differently Sensitive to Drought

Two wheat (Triticum durum Desf.) cultivars with different sensitivities to drought were either grown under regular irrigation or subjected to water deficit by withholding water for 14 d. Water-stressed plants of both cultivars underwent similar decreases in leaf water potential, but the drought-tolerant cultivar showed higher relative water content and turgor. Neither osmotic nor elastic adjustment mechanisms appeared to be active under the conditions described here. Thylakoids isolated from the stressed, drought-tolerant wheat showed an increase in lipid-to-protein ratio, in comparison with the control, whereas this ratio remained unchanged in the sensitive wheat. In both cultivars, water deficit determined different rearrangements in the composition of the thylakoid individual polar lipids, but their unsaturation level remained unaffected with the exception of monogalactosyldiacylglycerol. In the drought-sensitive cultivar, an accumulation of free fatty acids together with a reduction in polar lipid amount was observed. Electron paramagnetic resonance measurements of spin-labeled proteins of stressed plants from the sensitive cv Adamello showed a higher spin label rotational correlation time together with lower sulphydryl group and mobile proteic portion levels, in comparison with the control. In the tolerant cv Ofanto, the first two parameters changed to a lesser extent following water depletion, and the mobile proteic portion was not altered.     

Moniliformin Accumulation and other Effects of Fusarium avenaceum (Fr.) Sacc. on Kernels of Winter Wheat Cultivars

Accumulation of the mycotoxin moniliformin (MON) and other effects on kernels were examined in 13 Polish winter wheat cultivars inoculated with F. avenaceum (Fr.) Sacc. isolate ATCC 64451. Kernels from inoculated ears were divided into three fractions: Fusarium damaged kernels (FDK), kernels with black point symptoms (BPK) and healthy looking kernels (HLK). The average moniliformin content (mg/kg) was highest in chaff (11.69), lower in infested kernels (FDK + BPK) (2.70) and lowest in HLK (1.16). The mean level (mg/kg) of moniliformin in kernels (total sample) ranged from 0.78 in cv. Liwilla to 3.84 in cv. Gama. Moniliformin levels in chaff were correlated ( r = 0.5322) with the average metabolite concentration (mg/kg) in kernels, and ranged from 4.97 in chaff of cv. Roma to 22.9 of cv. Alba. The moniliformin concentration in kernels (total sample) was highly correlated with the level of the metabolite in diseased kernels. This is the first report of the relationship of black point symptoms with F. avenaceum colonization of kernels and moniliformin accumulation.     

薯蓣皂素对小麦幼苗抗旱性的影响

用不同浓度的薯蓣皂素喷施处理小麦幼苗叶片,研究薯蓣皂素在干旱胁迫下对小麦幼苗影响。结果表明,喷施一定浓度的外源薯蓣皂素,在干旱胁迫下可保持小麦幼苗叶片相对含水量,提高SOD和POD活性,降低MDA含量,对小麦幼苗抗旱有一定的作用。且薯蓣皂素最佳质量浓度为0.5 mg.L-1。     

冬小麦植物铁载体分泌的杂种效应

缺铁是石灰性土壤常见的植物营养问题之一。禾本科植物种或基因型的植物铁载体分泌能力与耐缺铁有关 ,提高植物铁载体分泌能力是改良缺铁的土壤上植物铁营养的关键措施之一。在水培条件下分析了冬小麦(TriticumaestivumL .) 3个杂交种及其 4个亲本在缺铁营养液中植物铁载体的分泌及杂种的效应。植物铁载体的分泌率通过根分泌物对新形成的Fe(OH) 3 的活化能力进行测定 ,在缺铁症出现时每隔 2、3天测定 1次。在缺铁条件下 ,所有基因型都分泌较多的植物铁载体 ,并且随缺铁症状的发展分泌量增加。杂交种具有对缺铁更敏感的反馈系统 ,在缺铁条件下 ,杂交种比亲本分泌铁载体的速度更快、量更高。通过分析杂交种和亲本的关系 ,认为可以通过对亲本分泌植物铁载体能力和配合力的选择 ,利用杂种优势来提高小麦铁的利用效率。     

Response of Two Wheat Cultivars to CO(2) Enrichment under Subambient Oxygen Conditions

Two cultivars of wheat (Triticum aestivum L. cvs Sonoita and Yecora Rojo) were grown to maturity in a growth chamber within four sub-chambers under two CO₂ levels (350 or 1000 microliters per liter) at either ambient (21%) or low O₂ (5%). Growth analysis was used to characterize changes in plant carbon budgets imposed by the gas regimes. Large increases in leaf areas were seen in the low O₂ treatments, due primarily to a stimulation of tillering. Roots developed normally at 5% O₂. Seed development was inhibited by the subambient O₂ treatment, but this effect was overcome by CO₂ enrichment at 1000 microliters per liter. Dry matter accumulation and seed number responded differently to the gas treatments. The greatest dry matter production occurred in the low O₂, high CO₂ treatment, while the greatest seed production occurred in the ambient O₂, high CO₂ treatment. Growth and assimilation were stimulated more by either CO₂ enrichment or low O₂ in cv Yecora Rojo than in Sonoita. These experiments are the first to explore the effect of whole plant low O₂ treatments on growth and reproduction. The finding that CO₂ enrichment overcomes low O₂-induced sterility may help elucidate the nature of this effect.     

Effects of Drought on Partitioning of Nitrogen in Two Wheat Varieties Differing in Drought-tolerance

A model was constructed to describe the translocation and partitioningof nitrogen on the seventh day after anthesis for well-wateredand droughted plants of two wheat varieties (Triticum aestivumL. cv. Warigal and Condor). The glasshouse-grown plants weredetillered so that a simplified model could be derived for themain stem. A 9-d drought treatment was imposed just after anthesisand this coincided with the period of endosperm cell divisionin the grains. Warigal, which had a higher grain yield thanCondor under drought, absorbed up to 15-times more nitrogenand translocated 1.5-fold more nitrogen to the shoot via thexylem. In both varieties, nitrogen redistributed from vegetativeorgans accounted for more than 60 per cent in control and 70per cent in droughted plants of the nitrogen needed for eargrowth. The net loss of nitrogen increased by 4-3 per cent inthe leaves, but decreased by 60 per cent in the stem under drought.Stem and roots appeared to play an important role in the nitrogeneconomy of droughted plants: less nitrogen was translocateddirectly to the grains from the senescing leaves and 40–60per cent more nitrogen was translocated to the roots. Nearlyall the nitrogen reaching the roots in the phloem was reloadedinto the xylem stream and translocated back to the shoot. Thetransfer of nitrogen through the stem was reduced under droughtand this resulted in a constant C:N ratio of the grains whichmay be important in the regulation of endosperm cell division. Triticum aestivum L., wheat, drought, nitrogen, senescence, translocation     

冬小麦植物铁载体分泌的杂种效应

缺铁是石灰性土壤常见的植物营养问题之一.禾本科植物种或基因型的植物铁载体分泌能力与耐缺铁有关,提高植物铁载体分泌能力是改良缺铁的土壤上植物铁aestivum L.) 3个杂交种及其4个亲本在缺铁营养液中植物铁载体的分泌及杂种的效应.植物铁载体的分泌率通过根分泌物对新形成的Fe(OH)3的活化能力进行测定, 在缺铁症出现时每隔2、3天测定1次.在缺铁条件下,所有基因型都分泌较多的植物铁载体,并且随缺铁症状的发展分泌量增加.杂交种具有对缺铁更敏感的反馈系统,在缺铁条件下,杂交种比亲本分泌铁载体的速度更快、量更高.通过分析杂交种和亲本的关系,认为可以通过对亲本分泌植物铁载体能力和配合力的选择,利用杂种优势来提高小麦铁的利用效率.     

Grain Yield in Two Contrasting Varieties of Spring Wheat

To investigate factors determining grain yield in spring wheattwo contrasting varieties of high (Jufy I) and low (Peko) yieldingcapacity were grown in field and glasshouse experiments. In a field trial Jufy I yielded approximately 14 per cent moregrain than Peko on both control and nitrogen-treated plots.In another field trial employing small plots, although for bothvarieties doubling the seed-rate did not affect grain yield,the two varieties differed in their response to the increasein density. In Peko the yield level remained unaffected becausedoubling the seed-rate halved the number of fertile tillersper plant, whereas for Jufy I in addition to a shift in tillernumber per plant there were changes in the number of grainsper ear. In both varieties the weight per seed remained constant. When the two varieties were grown alone or as a 1: 1 mixtureat the same seed-rate the grain yields were similar. In themixture, Peko, compared with Jufy I, produced a greater numberof fertile tillers and consequently a greater contribution tothe total grain yield. In glasshouse experiments the grain yield per tiller and theorder of leaf area duration per tiller for the period from earemergence to grain ripening were both higher for Jufy I. Onthe other hand, there was no varietal difference for the netassimilation rate estimated during the vegetative phase, butexcluding the roots. Additional nitrogen primarily stimulated tiller production inboth varieties. Shading either the upper or lower parts of the plant demonstratedthat the ear and flag leaf and its sheath are important sourcesof assimilates for grain formation, whereas the lower partsare relatively unimportant in this respect. There were indicationsthat the response between varieties differed.     

黄淮麦区小麦品种(系)的ISSR位点遗传多样性分析

选用11个ISSR引物,对黄淮麦区96个小麦推广品种（系）进行遗传多样性分析。共检测到96个多态性位点,每个引物多态性位点数平均为8．7个,变幅为3～23个;ISSR引物的多态性信息含量PIC变幅为0．601～0．941,平均0．791,表明ISSR具有较强的品种间区分能力,是研究小麦种质资源遗传多样性的有效分子标记技术之一。96个品种（系）间,Nei’s遗传相似系数变化范围为0．53～0．91,平均为0．60,品种间遗传相似性变幅较大,表明黄淮麦区不同小麦品种（系）间存在着不同程度的遗传多样性差异。根据品种间遗传相似系数聚类,96份材料被聚成8大类群,共14个亚类,类群与系谱和原产地无关。