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1.
Nocturnal warming has various effects on plant biomass production. To understand how biomass production of the dominant grassland species Leymus chinensis responds to summer nocturnal warming in the eastern temperate Eurasian steppes, we simulated summer nocturnal warming (+4 °C) using a phytotron system for 100 days operated based on the variation of diurnal temperatures over the past 12 years in the Songnen Grasslands. Our results show summer nocturnal warming significantly increased above‐ground biomass production of parent and daughter shoots as well as increased below‐ground root and rhizome biomass production; rhizome biomass increased faster than root biomass leading to an increase in the rhizome biomass to root biomass ratio. Nocturnal warming slightly increased the number of daughter shoots per plant, and significantly increased the number of buds in the below‐ground bud bank and the number and length of rhizomes per plant. Also, the dark respiratory and net photosynthetic rates, Jmax, the rate of triosephosphate utilization and chlorophyll fluorescence parameters (ΦPSII and qP) were significantly higher under nocturnal warming conditions. These findings show that nocturnal warming in this ecosystem improves individual biomass accumulation due to photosynthetic compensation, and may enhance the population density and productivity of L. chinensis by increasing bud number in the below‐ground bud bank during the early stage of ecological succession for grasslands dominated by L. chinensis.  相似文献   

2.
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3.
Brassica rapa L. is a genetically diverse parent species of the allotetraploid species, oilseed rape (B. napus) and a potential source of drought tolerance for B. napus. We examined the effect of a 13‐day drought stress period during the early reproductive phase, relative to a well‐watered (WW) control, on subsequent growth and development in nine accessions of B. rapa and one accession of Brassica juncea selected for their wide morphological and genetic diversity. We measured leaf water potential, stomatal conductance, water use, and leaf and bud temperatures during the stress period and aboveground dry weight of total biomass at maturity. Dry weight of seeds and reproductive tissue were not useful measures of drought tolerance due to self‐incompatibility in B. rapa. The relative total biomass (used as the measure of drought tolerance in this study) of the 10 accessions exposed to drought stress ranged from 47 % to 117 % of the WW treatment and was negatively correlated with leaf‐to‐air and bud‐to‐air temperature difference when averaged across the 13‐day stress period. Two wild‐type (B. rapa ssp. sylvestris) accessions had higher relative total and non‐reproductive biomass at maturity and cooler leaves and buds than other types. We conclude that considerable genotypic variation for drought tolerance exists in B. rapa and cooler leaves and buds during a transient drought stress in the early reproductive phase may be a useful screening tool for drought tolerance.  相似文献   

4.
彰武松腋芽诱导研究   总被引：2，自引：2，他引：0  
为了探讨彰武松组培快繁的可行性,以彰武松封顶芽为外植体进行培养,研究灭菌方法、培养基成分以及植物生长调节物质等对其腋芽诱导的影响。结果表明：外植体用70%的乙醇处理30 s后用0.1%的HgCl2灭菌5 min,在添加BA 2~5 mg/L和蔗糖30 g/L的WPM培养基上,腋芽诱导率达50%~70%,NAA对腋芽诱导无促进作用。通过在添加和不添加植物生长调节物质(PGR)的WPM培养基中交替继代培养可以实现芽丛伸长与增殖。  相似文献   

5.
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6.
Perennial grass‐based pastures are uncommon in phased cropping rotations in south‐eastern Australia, where rainfall often limits production and persistence. The high reliance on pure legume‐based pastures limits overall pasture productivity and has adverse effects on environmental parameters such as weed incursion and ground cover. A field experiment was monitored over 5 years to examine the relative productivity of the temperate perennial grasses, phalaris (Phalaris aquatica) and cocksfoot (Dactylis glomerata) and determine whether contrasting seasonal activity enhances their persistence when grown in mixtures with lucerne (Medicago sativa) and annual legumes. Phalaris swards were shown to increase cumulative aboveground biomass by up to 96% and 32%, and in year 5 reduce annual grass emergence by between sevenfold and threefold compared to annual legume and lucerne/annual legume mixed swards, respectively. Only swards that included phalaris maintained ground cover above 70% in each autumn of the experimental period. Swards based on the highly summer dormant cocksfoot cultivar, Kasbah, were generally less productive over all, despite the cocksfoot showing a high level of persistence and good recovery following drought. Grass‐based swards that included lucerne were observed to produce ~35% greater legume biomass than a sward sown only to annual legumes. Cumulative legume biomass was greatest in lucerne swards in the absence of perennial grasses. The experiment was unable to demonstrate a consistent benefit in production and persistence associated with contrasting seasonal growth patterns. However, mixtures containing a range of functional types were consistently shown to enhance productivity over the duration of the experiment compared to less diverse swards. The potential to substantially increase forage productivity and ground cover, while reducing incursion by annual grass weeds, by including well‐adapted perennial grasses in mixtures with lucerne and annual legumes should be utilized.  相似文献   

7.
建立一个高效稳定的植株再生系统是番木瓜生物技术育种和品种改良的关键。本研究通过横向薄层培养技术,以‘一尺瓜’番木瓜品种为材料,通过对田间成年结果树截干后萌生的侧芽进行消毒处理,经过初代培养和增殖培养后获得大量丛生分化芽。以健壮分化芽为材料横向切取1~2.5 mm厚度的薄层6~10片,经不定芽诱导和增殖培养后进行生根培养,成功获得植株再生。研究结果表明,采用300 mg/L利福平溶液浸泡并在摇床上140 r/min振荡处理1 h、75%酒精处理30 s、0.1%的氯化汞溶液(W/V)处理7~8 min的组合递进式消毒处理方法,可使侧芽接种培养成功率达到85%以上。分化芽薄层在MS培养基+30 mg/L蔗糖+0.1 mg/L6-BA+0.2 mg/L NAA+0.3 mg/L KT+0.1 mg/L IBA的条件下诱导培养20 d,单个分化芽切取的薄层平均可获得7.04个不定芽,其中第3号薄片出芽能力最强,平均出芽数可达到3.4个,最高5.0个。采用将叶尖代替分化芽茎基部插入培养基的茎段悬空植叶促根方法进行分化芽的促根培养,生根培养基组成为1/2MS培养基+3%蔗糖(W/V)+2 mg/L IBA,20~25 d后平均出根率可达到87.5%,根系无结构疏松和愈伤化现象,假植成活率可高达95%以上,有效改善了常规生根技术存在的根系质量差和假植成活率低的问题。本研究结果可提高番木瓜组培快繁效率,并为番木瓜诱变育种和分子育种提供技术支撑。  相似文献   

8.
辽宁苗期玉米根叶对水分胁迫的响应   总被引：1，自引：0，他引：1  
为了提炼辽宁春玉米苗期干旱胁迫影响的定量化评价指标,以‘丹玉39’为试验材料,采用盆栽称重控水法,对不同水平土壤含水量对春玉米苗期根叶生长的影响进行研究。结果表明：正常（75%）和偏湿（85%）水分条件下玉米具有较高的株高,茎粗和叶面积。干旱胁迫下,玉米生长发育受到抑制,株高降低、茎粗变细、根系和地上部的生物量降低,叶片光合面积减小,根冠比增大。但一定程度的干旱（55%）有利于根系下扎,增大根冠比。干旱胁迫对玉米的株高和根系的生长发育有较大的影响,地上生物量受干旱胁迫影响大于根系。  相似文献   

9.
Drought and high temperature are major environmental stress factors threatening wheat production during grain filling stage resulting in substantial yield losses. Four wheat genotypes (Suntop, IAW2013, Scout and 249) were planted under two temperature levels (25 and 30°C) and two water levels (15% and 25% soil moisture content). Wheat yield, leaf δ13C, plant rhizodeposition, shoot biomass and root traits were examined. Low moisture (drought stress) and high temperature (heat stress) decreased the grain yield of all wheat genotypes, in particular 249, while combined drought and temperature stresses had the most pronounced negative effect on plant biomass and grain yield. Decreasing soil water availability decreased the allocation of plant‐derived C to soil organic carbon (SOC) and to microbial biomass through rhizodeposition. Leaf δ13C decreased with increased yield, suggesting that higher yielding genotypes were less water stressed and allocated less C to SOC and microbial biomass through rhizodeposition. Wheat genotypes with lower root/shoot ratios and thinner roots were more efficient at assimilating C to the grain, while genotypes with higher root/shoot ratios and thicker roots allocated more C belowground through rhizodeposition at the expense of producing higher yield. Therefore, improving these traits for enhanced C allocation to wheat grain under variable environmental conditions needs to be considered.  相似文献   

10.
Summary Leaf cuttings without axillary buds were made from young vegetative beet plants. Roots were formed at the petiole end. Adventitious bud formation occurred at a very low frequency and could not be stimulated by application of growth regulators. Leaf cuttings with axillary buds formed plants at a higher frequency but development of buds into shoots was slow and irregular. As no vascular connections were found between petiole and axillary bud, the slow growth of the buds was attributed to insufficient supply of assimilates from the leaves. Axillary buds rapidly developed into shoots when petiole explants with buds were placed on culture media. Nearly all cultures, however, were contaminated with bacteria that originated from the inner tissue of the explants.  相似文献   

11.
Field experiments were conducted at Coimbatore, India to study the effect of three levels of drought (severe, moderate and no drought) during the formative phase (60–150 days after planting; DAP) of sugarcane on the tillering, the conversion of shoots to millable canes, cane attributes and the quality of different classes of shoots in four sugarcane cultivars (Co 8021, Co 419, Co 8208 and Co 6304)_the different classes of shoots studied were: mother shoots (which emerged 0–30 DAP), early tillers (30–60 DAP), mid‐season tillers (60–150 DAP) and late tillers (150 DAP). The results indicated that drought during the formative phase reduced the total number of shoots and their conversion to millable canes at harvest. Drought also reduced the cane length, number of inter‐nodes and single cane weight of different classes of shootsand the subsequent total cane yield. Irrespective of drought treatments, Co 8021, a high‐tillering, thick‐stalked cultivar, gave the highest cane yield despiteits higher shoot mortality, while Co 8208, a low‐tillering, thin‐stalked cultivar, gave the lowest cane yield despite its lower shoot mortality. Thus a moderate level of shoot mortality is clearly necessary to obtain higher millable canes and subsequently higher cane yield. Mother shoots and early tillers together contributed most of the total number of millable canes (84.5 %) and of the total cane yield at harvest (86.2 %). The contribution of late tillers to the number of millable canes and cane yield was, however, negligible, especially in cultivars Co 6304 and Co 8208. There was a gradual reduction in stalk attributes such as cane length, number of internodes, single cane weight and commercial cane sugar percentage as the physiological age of shoots decreased. This study emphasizes the need for a cultivar with the optimal characteristics of early tillering (like Co 8021 and Co 6304) and maximum conversion to millable canes (like Co 8208) and provides information relevant to breeders making decisions on crossing programmes to produce improved cultivars for drought conditions.  相似文献   

12.
The biomass allocation pattern of plants to shoots and roots is a key in the cycle of elements such as carbon, water and nutrients with, for instance, the greatest allocations to roots fostering the transfer of atmospheric carbon to soils through photosynthesis. Several studies have investigated the root to shoot ratio (R:S) biomass of existing crops but variation within a crop species constitutes an important information gap for selecting genotypes aiming for increasing soil carbon stocks for climate change mitigation and food security. The objectives of this study were to evaluate agronomic performance and quantify biomass production and allocation between roots and shoots, in response to different soil water levels to select promising genotypes for breeding. Field and greenhouse experiments were carried out using 100 genotypes including wheat and Triticale under drought‐stressed and non‐stressed conditions. The experiments were set‐up using a 10 × 10 alpha lattice design with two replications under water stress and non‐stress conditions. The following phenotypic traits were collected: number of days to heading (DTH), number of productive tillers per plant (NPT), plant height (PH), days to maturity (DTM), spike length (SL), kernels per spike (KPS), thousand kernel weight (TKW), root biomass (RB), shoot biomass (SB), root to shoot ratio (R:S) and grain yield (GY). There was significant (p < 0.05) variation for grain yield and biomass production because of genotypic variation. The highest grain yield of 247.3 g/m2 was recorded in the genotype LM52 and the least was in genotype Sossognon with 30 g/m2. Shoot biomass ranged from 830 g/m2 (genotype Arenza) to 437 g/m2 (LM57), whilst root biomass ranged between 603 g/m2 for Triticale and 140 g/m2 for LM15 across testing sites and water regimes. Triticale also recorded the highest R:S of 1.2, whilst the least was 0.30 for wheat genotype LM18. Overall, drought stress reduced total biomass production by 35% and R:S by 14%. Genotypic variation existed for all measured traits useful for improving drought tolerance, whilst the calculated R:S values can improve accuracy in estimating C sequestration potential of wheat. Wheat genotypes LM26, LM47, BW140, LM70, LM48, BW152, LM75, BW162, LM71 and BW141 were selected for further development based on their high total biomass production, grain yield potential and genetic diversity under drought stress.  相似文献   

13.
Although several studies have been made on the micropropagation of Jatropha curcas using agar base mediums, none of them have been by using liquid medium systems. The effects of explant type and temporary immersion system (test tube, jar with filter paper boat, and growtek bioreactor) on the micropropagation of J. curcas were studied. The explant type influenced shoot quality, multiplication coefficient (MC), and rooting. Leaf explant produced more and longer shoots than nodal explant. Use of filter paper (FB) boat prevented hyperhydricity and allowed proliferation of nodal explants cultured in liquid MS (Murashige and Skoog) medium supplemented 6-benzylaminopurine (BAP) and Kinetin (KN). The best shoot bud induction (92.1±3.1%) was achieved in liquid MS medium supplemented with 2.0 mg/L KN. Leaf regeneration efficiency was compared in growtek bioreactor and in jar containing liquid MS medium supplemented with 0.5 mg/L Thidiazuron (TDZ). The best shoot bud regeneration (78.7±2.1%) was obtained in growtek bioreactor. Shoot buds achieved from nodal segment and leaf were subcultured on filter paper boats in jar and bioreactor containing liquid MS medium supplemented with BAP, Indole butyric acid (IBA), Indole-3-acetic acid (IAA), and KN. Best shoot proliferation and elongation was obtained in filter paper boats containing liquid MS medium supplemented with 1.5 mg/L BAP, 0.5 mg/L IAA, and 0.2 mg/L KN. The number of multiple shoot buds was higher in leaf explants as compared to nodal explants and the highest number of multiple shoot buds was recorded from leaf explants. Up to 76.4% rooting efficiency was obtained when the shoots were ex vitro rooted. The generated plants well established in the nursery and grew normally in outdoor conditions. The protocol has good potential for application in large-scale propagation of J. curcas using liquid medium.  相似文献   

14.
Adventitious shoots: Do they develop from one cell?   总被引：6，自引：0，他引：6  
C. Broertjes  A. Keen 《Euphytica》1980,29(1):73-87
Summary One of the bottle-necks in mutation breeding of vegetatively propagated crops is the chimera formation after irradiation of multicellular apices in buds of vegetative material. This difficulty can be overcome with in vivo or in vitro adventitious bud techniques which, in combination with radiation, give almost exclusively solid, non-chimeric mutants and unmutated plants. This is usually explained on the basis of the ultimate development of the apex of adventitious shoots from single (epidermal) cells.To investigate whether chimera formation is a matter of chance as a result of which genotypically different cells form the apex of an adventitious shoot, a stochastic model has been developed which describes the process of apex formation and by which the expected relative chimera percentages E(RCP's) are calculated. The discrepancy between these RCP's and the actual figures obtained in various crops, either propagated in vivo or in vitro, leads to the postulate that the apex of the adventitious shoot is formed from only one (epidermal) cell of the meristem or the callus. Another possibility is thatapex formation is not a random process and that the first dividing cell, forming the future meristem or callus, soon occupies the major part of this meristem, on top of which a few cells (most likely genetically identical vegetative daughter cells-mutated or unmutated) form the apex of the adventitious shootlet.  相似文献   

15.
Drought is the single most important factor limiting soya bean (Glycine max L. Merr.) yields in the field. The following study was therefore undertaken to identify phenotypic markers for enhanced drought tolerance in nodulated soya beans. Leaf and nodule parameters were compared in three genotypes: Prima 2000, glyphosate‐resistant A5409RG and Jackson, which had similar shoot biomass and photosynthesis rates at the third trifoliate leaf stage under water‐replete conditions. When water was withheld at the third trifoliate leaf stage, photosynthesis, nodule numbers, nodule biomass and symbiotic nitrogen fixation (SNF) were greatly decreased. Significant cultivar–drought interactions were observed with respect to photosynthesis, which also showed a strong positive correlation with nodule SNF, particularly under drought conditions. Prima leaves had high water‐use efficiencies, and they also maintained high photosynthetic electron transport efficiencies under long‐term drought. Moreover, Prima had the highest shoot biomass under both water‐replete and drought conditions. A‐5409RG was the most drought‐sensitive genotype showing early closure of stomata and rapid inhibition of photosynthesis in response to drought. In addition to classifying the genotypes in relation to drought tolerance, the results demonstrate that the ability to sustain shoot biomass under nitrogen limitation is an important parameter, which can be easily applied in germplasm screening for drought tolerance in soya bean.  相似文献   

16.
Backcross hybrids between the important forage legume white clover Trifolium repens , which is stoloniferous, and the related rhizomatous species T. ambiguum have been produced using T. repens as the recurrent parent. The drought tolerance of parents and two generations of backcross plants, possessing both stolons and rhizomes, was studied in deep soil bins in a glasshouse both as monocultures and in mixtures with perennial ryegrass. Soil moisture content, leaf relative water content, and leaf water potential were measured on plants subjected to drought cycles of 4 weeks duration and those watered normally and maintained at field capacity. Six cycles of drought, carried out over 2 years, showed that T. ambiguum and the first and second generation backcross hybrids maintained a greater leaf relative water content and higher leaf water potential than T. repens at comparable levels of soil moisture. The dry matter yield of T. repens was significantly reduced over each drought cycle compared to the watered treatments, while the yield of T. ambiguum increased over the 4-week cycle in both treatments. The yield of the backcross generations was intermediate between those of the two parental species. The implications of these results for white clover germplasm improvement programmes are discussed.  相似文献   

17.
The objectives of this research were to establish a practicable phenotyping platform for assessing the drought stress response of perennial ryegrass (Lolium perenne L.; Lp), and to use this platform for evaluating the variation for drought tolerance among a panel of 39 diverse Lp populations. A moderate‐to‐strong correlation was assessed between the performance of plants grown in a hydroponics system, where the stress was generated by the addition of polyethylene glycol (PEG), and those grown in the field in a rainout shelter. Following the application of drought stress, tetraploid Lp populations, along with a small number of reference Festulolium and Festuca sp. accessions, were able to develop more shoot and root dry matter than diploid Lp populations. The onset of drought symptoms was also delayed within these accessions and the plants recovered better once drought had been relieved. Although most of the diploid Lp populations were drought susceptible, there was a considerable accession‐to‐accession variation for performance under drought stress conditions. Measuring biomass production and post‐drought recovery in rainout shelter experiments in combination with the assessment of root biomass accumulation in PEG‐supplemented hydroponics represented a viable means of screening Lp germplasm for drought tolerance.  相似文献   

18.
甘蓝型油菜花茎高效再生体系研究   总被引：2，自引：1，他引：1  
研究了甘蓝型油菜花茎外植体高效诱导不定芽的再生体系,结果表明：以含有2,4-D（0.5~1.0mg/L）的培养基对外植体进行预培养,以及在分化培养基中加入AgNO3（2~6mg/L）,可显著降低外植体褐化坏死的频率,提高了不定芽的发生频率及其再生能力;6BA（2.5 mg/L）与NAA（0.1mg/L）配合使用有利于提高不定芽发生频率;再生的不定芽90%可长根  相似文献   

19.
Process-based models usually are complex and require a large number of input data, which restrain their use for prediction of forest growth. To overcome those difficulties, efforts have been made towards their simplification by integrating both empirical and mechanistic elements at the same hierarchical level. In this study, we investigated the reliability of such a model for projecting productivity in willow coppice systems. Willow forest growth was assumed proportional to the global radiation intercepted by the canopy during the vegetation period. The radiation use efficiency concept was combined with mortality functions based on self-thinning to simulate the accumulated biomass. The model was calibrated against annual stem biomass data from a fertilised and irrigated experimental stand situated near Uppsala (central Sweden) and validated against data from several other fertilised stands located in central and southern Sweden, all representing close to optimal nitrogen conditions. The model was able to explain 81% of the observed variations in standing biomass of 1-year-old shoots, almost none of the variations after the second year, and 52% for 3-year-old shoots. Thus, willow productivity of especially shoots older than 1 year was only partially possible to reproduce based on incident radiation, shoot age and shoot mortality. This might be explained by low performance of the radiation interception and mortality estimations, as well as, the assumption of optimum conditions being maintained throughout the period may not have been met.  相似文献   

20.
Alfalfa (Medicago sativa L.) production is negatively affected by drought stress. This is particularly true for alfalfa grown on non‐irrigated rangelands. Thus, the development of drought‐tolerant alfalfa cultivars is of great significance. A greenhouse study was conducted to evaluate 11 alfalfa accessions including several that are adapted to rangeland conditions and two commercial accessions, for their performance under drought condition. Water supply was adjusted based on the transpiration rate of individual plants to compensate for 100, 75, 50 or 25 % of transpirational water loss. We found that RS, a naturalized alfalfa collected from the Grand River National Grassland in South Dakota, showed the best resistance to drought condition. It showed the smallest reduction in stem elongation (36 %), relative growth rate (14 %), and shoot dry mass (40 %) production under the severest drought tested in this study relative to the non‐drought treatment. While RS showed less biomass production under well‐watered conditions, it produced similar or more shoot biomass under drought conditions compared to other accessions. Associated with the drought resistance or less sensitivity to drought, RS showed greater capability to maintain root growth, shoot relative water content, and leaf chlorophyll content compared to other accessions. Different from other accessions, RS showed increasing water use efficiency (WUE) as water deficit became severe, reaching the greatest WUE among 11 accessions. Our results suggest that RS is a valuable genetic resource that can be used to elucidate physiological and molecular mechanisms that determine drought resistance in alfalfa and to develop alfalfa with improved WUE.  相似文献   

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