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1.
方平  姚启伦  陈发波 《种子》2012,31(1):5-8
以10个来自三峡库区的玉米地方品种为材料,通过盆栽实验和设置低氮胁迫处理,研究低氮胁迫下玉米地方品种的苗期植株形态和生理效应.结果表明,低氮胁迫对玉米地方品种幼苗植株形态和生理有不同程度的不利影响,不同玉米地方品种的耐低氮特性存在明显差异.不同地方品种的同一植株性状和同一地方品种的不同植株性状的耐低氮胁迫指数存在差异.侧根数、叶面积、根体积和植株干重可作为玉米地方品种耐低氮种质筛选的形态指标,硝酸还原酶活性和丙二醛含量可作为耐低氮种质筛选的生理指标.此外,三峡库区玉米地方品种中有较丰富的耐低氮种质可供玉米育种利用.  相似文献   

2.
Drought stress is a major limiting factor for crop production in the arid and semi‐arid regions. Here, we screened eighty barley (Hordeum vulgare L.) genotypes collected from different geographical locations contrasting in drought stress tolerance and quantified a range of physiological and agronomical indices in glasshouse trails. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at three‐leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, root length of the same genotypes was measured from stress‐affected plants growing hydroponically. Drought tolerance was scored 30 days after the drought stress commenced based on the degree of the leaf wilting, fresh and dry biomass and relative water content. These characteristics were related to stomatal conductance, stomatal density, residual transpiration and leaf sap Na, K, Cl contents measured in control (irrigated) plants. Responses to drought stress differed significantly among the genotypes. The overall drought tolerance was significantly correlated with relative water content, stomatal conductance and leaf Na+ and K+ contents. No significant correlations between drought tolerance and root length of 6‐day‐old seedling, stomatal density, residual transpiration and leaf sap Cl? content were found. Taking together, these results suggest that drought‐tolerant genotypes have lower stomatal conductance, and lower water content, Na+, K+ and Cl? contents in their tissue under control conditions than the drought‐sensitive ones. These traits make them more resilient to the forthcoming drought stress.  相似文献   

3.
Plant genotypes with higher drought tolerance through improved root characteristics are poorly studied in orchardgrass. In the current research, 30 orchardgrass genotypes were polycrossed and the resulting half‐sib families evaluated under both normal and water stress environments. Under water stress conditions, values for most root traits decreased at 0–30 cm soil depth, while at 30–60 cm depths, the root length (RL), root area (RA), root volume, percentage of root dry weight (RDW) and the ratio of root to shoot were increased. We identified drought‐tolerant genotypes with a high combining ability for root characteristics and a high yield potential. High estimates of heritability as well as genetic variation for root traits indicated that phenotypic selection would be successful in order to achieve genetic progress. Indirect selection to improve dry matter yield was most efficient when selecting for RL and RDW under water stress conditions. Significant associations between a drought tolerance index and RL, RA and root volume confirmed the importance of these traits in conferring drought tolerance of orchardgrass.  相似文献   

4.
Although the root system is indispensable for absorption of nutrients and water, it is poorly studied in maize owing to the difficulties of direct measurement of roots. Here, 103 maize lines were used to compare root architectures under well-watered and water-stressed conditions. Significant genetic variation, with medium to high heritability and significant correlations, was observed for root traits. Total root length (TRL) and total root surface area (TSA) had high phenotypical diversity, and TRL was positively correlated with TSA, root volume, and root forks. The first two principal components explained 94.01% and 91.15% of total root variation in well-watered and water-stressed conditions, respectively. Thus, TRL and TSA, major contributors to root variation, can be used as favorable selection criteria at the seedling stage. We found that stiff stalk and non-stiff stalk groups (temperate backgrounds) showed relatively higher mean values for root morphological diversity than the TST group (tropical/subtropical background). Of the tested lines, 7, 42, 45, and 9 were classified as drought sensitive, moderately sensitive, moderately drought tolerant, and highly drought tolerant, respectively. Seven of the 9 extremely drought tolerant lines were from the TST group, suggesting that TST germplasms harbor valuable genetic resources for drought tolerance that could be used in breeding to improve abiotic stress tolerance in maize.  相似文献   

5.
Improving white clover drought tolerance by selecting for more developed roots is controversial, labour‐consuming and complicated by the adventitious root system. This study aimed at assessing: (i) the value of thicker stolons as an indirect selection criterion for increasing root development, (ii) the relationship between root development and drought tolerance, and (iii) the consistency of population response for root and shoot traits between swards derived from seedlings or stolon cuttings. Thick‐ and thin‐stolon populations obtained by one cycle of divergent phenotypic selection within one ladino landrace, and one ladino natural population, were evaluated in metal containers (0.55 m × 0.12 m × 0.75 m deep) in a 1‐year experiment including vegetative material (seedling or stolon cutting) and drought stress (absent or present) as additional factors. Aerial dry weight (DW) was also assessed across two summer harvests under irrigated and rainfed field conditions for the thick‐stolon selection, two breeding populations selected from the same landrace regardless of stolon thickness, and the drought‐tolerant ladino ‘Brown Loam Synthetic no. 2’. The thick‐stolon selection had greater root DW (+21 %) than the thin‐stolon selection besides thicker stolons (+23 %). The natural population combined thinnest stolons with lowest root DW. Differences between populations were consistent across vegetative material. Primary and adventitious root systems did not differ for root DW in deeper soil horizons (>23 cm), above‐ground biomass and its reduction due to drought stress. Root DW increased under stress, particularly in deeper horizons. Aerial DW variation among populations evened up or narrowed much under stress, with no cross‐over interaction leading to an advantage of thick‐stolon material or ‘Brown‐Loam Synthetic no. 2’.  相似文献   

6.
Drought stress is an important limitation for potato (Solanum tuberosum L.) production as potato depends on appropriate water availability for high yields of good quality. Therefore, especially in the background of climate change, it is an important goal in potato breeding to improve drought stress tolerance. In this study, 34 European starch potato cultivars were evaluated for drought stress tolerance by growing under well‐watered and long‐term drought stress conditions in rainout shelters in 2 years’ pot trials. Besides yield, six physiological traits, that is free proline content, osmolality, total soluble sugar content, chlorophyll content (SPAD), cell membrane stability and crude protein content, were determined in leaves sampled during vegetative growth and during flowering to investigate their association with drought tolerance. ANOVA revealed significant treatment effects for all physiological traits and increased genotypic effects at flowering. The sensitivity of physiological traits to drought was significantly higher during flowering than during vegetative growth. Drought stress decreased starch yield significantly (p < .001), on average by 55%. Starch yield was significantly influenced by genotype and genotype × treatment interactions. Stress tolerance index (STI) calculated from starch yield ranged from 0.26 (sensitive) to 0.76 (tolerant) with significant genotype effects (p ≤ .001). STI correlated positively with cell membrane stability (r = .59) and crude protein content (r = .38) and negatively with osmolality (r = ?.57) and total soluble sugar content (r = ?.71). These contrary correlations suggest a dual adaptation strategy in potato under long‐term drought stress conditions including increased membrane stability combined with an increased osmolality due to an increased soluble sugar content.  相似文献   

7.
研究绿豆芽期抗旱指标,为绿豆品种抗旱性鉴定和品种筛选提供理论依据。本试验采用15%的PEG-6000高渗溶液对58份绿豆品种（系）进行干旱模拟胁迫,测定其发芽率、发芽势、发芽指数、活力指数和相对根长等指标。结果表明：在15%的PEG浓度条件下,绿豆的各指标均受到不同程度的抑制,发芽势受抑制最大,下降30.62%;而相对根长受抑制较小,仅下降5.63%。且各指标的变异系数均有增加,说明绿豆生理指标在干旱胁迫下变化更显著。利用隶属函数分析法,筛选出1份高抗和4份抗性品种。  相似文献   

8.
Cotton breeders in the United States strive to develop region‐specific genotypes adapted to low temperatures and variable soil moistures during early‐season planting. Nine elite upland cotton germplasm (Gossypium hirsutum L.) lines, representing public breeding programmes from nine states across the cotton belt, were evaluated for cold and drought stresses during seed germination and seedling growth stages. Lines were subjected to three treatments, such as low temperature well‐watered (22/14°C, WW), optimal temperature drought stress (30/22°C, DS) and optimal temperature well‐watered (30/22°C, WW; control), to examine genotypic variability for cold and drought tolerance. The treatment including drought stress was irrigated at 50% of the control. Shoot and root traits measured at 25 days after planting were significantly affected by drought and low temperature, where significant genetic variability among lines was observed for both shoot and root parameters. Response indices were developed to quantify variation in the degree of tolerance among the lines to low temperature and drought. Accordingly, OA‐33 was identified as the most low‐temperature‐tolerant line and Acala 1517‐99 as the most drought‐tolerant line. Identification of both cold‐ and drought‐tolerant genotypes suggests existing genotypic variability could provide breeders the opportunity to improve cultivar response to early‐season drought or cold conditions.  相似文献   

9.
O. P. Yadav 《Plant Breeding》2008,127(2):208-210
The crop cultivars targeted for drought prone areas need to combine drought tolerance and high yield. The present study was conducted to assess the performance of three selected pearl millet landraces, four exotic elite populations and their 12 crosses. They were evaluated for yield, yield components and a drought susceptibility index that was calculated using yield data from drought and non‐drought environments. In the non‐drought season, the exotic populations had significantly higher grain yield than landraces. However, in the severe drought season, the landraces produced significantly greater biomass, grain and stover yields than elite populations. There was a strong relation between panicle size and ability to produce panicles and delay in flowering under severe stress. The biomass and stover yield of crosses was significantly better than parental populations under both drought stress and near‐optimum conditions. The elite populations were most sensitive to drought while crosses were as drought tolerant as landraces because they combined larger panicle size of exotics and lesser delay in flowering of landraces. The results indicated that it is possible to combine drought adaptation with high yield potential through hybridization between adapted landraces and elite genetic materials.  相似文献   

10.
Drought is a severe abiotic stress and the major constraint on wheat (Triticum aestivum L.) productivity world wide. Deciphering the mechanisms of drought tolerance is a challenging task because of the complexity of drought responses, environmental factors and their interactions. The objective of this study was to evaluate the ability of the antioxidative defence system in imparting tolerance against drought‐induced oxidative stress and yield loss in two wheat genotypes, when subjected to long‐term field drought. Drought resulted in an increase in H2O2 accumulation and lipid peroxidation and decrease in ascorbate level in roots and leaves at different plant developmental stages. Drought‐tolerant genotype having higher antioxidative enzymes activities, and ascorbate level was superior to that of sensitive genotype in maintaining lower H2O2 content and lipid peroxidation and higher growth, yield and yield components under water deficit. Various antioxidative enzymes showed positive correlation with ascorbate and negative with H2O2 content. In developing grains, antioxidative defence response was nearly similar among both the genotypes under control condition; however, sensitive genotype failed to modulate the activities of antioxidative enzymes according to the ROS rush under field drought. Poor capacity of the antioxidative defence system in vegetative and reproductive tissues of sensitive genotype seems to be responsible, at least partly, for reduced yield potential under water deficit.  相似文献   

11.
Brazil is the world's largest producer of common beans (Phaseolus vulgaris L.). Drought stress harms the morphological and agronomic traits of beans. This study evaluates the reaction to water deficit in five genotypes of black beans. The experiment was conducted in the IDR-IAPAR-EMATER in Londrina-PR, Brazil. A split-plot design was used, with three replications. The genotypes were included in the subplots and the treatments with or without water deficit in the plots. Water deficit was induced on the pre-flowering stage and maintained for 20 days in the plots submitted to drought stress. For the growth analysis, plants were collected at 35, 54 and 70 days after emergence. At the stage of physiological ripeness, several morphological and yield traits were evaluated. The genotypes IPR Uirapuru and BRS Esplendor can be considered tolerant and used as a tolerant source to water deficit in common bean germplasm banks. The line LP 08-90 has morphological and agronomic adaptations efficient to overcome water deficit's effects, presenting a higher grain yield in both crop conditions, which indicates the success of black beans breeding to deal with water deficit.  相似文献   

12.
Drought stress limits crop growth and yield in soya bean (Glycine max [L.] Merr.), but there are relatively few tools available to assess the ability of different genotypes to tolerate drought. Aerial infrared image analysis was evaluated as a potential tool for identifying drought tolerance in soya bean. Drought effects were evaluated from late vegetative to mid‐reproductive stages of soya bean development in an experiment with ten genotypes including five slow‐ and five fast‐wilting genotypes that were from a population derived from Benning×PI416937. There were two deficit irrigation levels for 2 years and one deficit irrigation level for the third year along with a fully irrigated control level. When the canopy was completely closed, relative canopy temperature was determined using an infrared camera taken from an aerial platform 50–75 m above the experiment. As water availability decreased, the relative canopy temperature generally increased. Moreover, slow‐wilting soya bean genotypes generally had lower canopy temperature compared to fast‐wilting genotypes, and grain yield was generally positively associated with cool canopy temperatures. The results indicate that the determination of canopy temperature is a promising tool for rapid characterization of drought‐related traits in soya bean.  相似文献   

13.
Drought is the major constraint limiting rainfed rice production. The ability of rice roots to penetrate compacted soils and therefore to increase water extraction capacity, osmotic adjustment and dehydration tolerance of leaves enables the plant to tolerate drought. Experiments were conducted to determine the extent of genetic variation in root penetration index, osmotic adjustment and dehydration tolerance among indica accessions adapted to rainfed lowlands as well as traditional varieties from rainfed uplands. Root penetration index was evaluated in a system using wax–petrolatum layers to simulate soil compaction. Osmotic adjustment and dehydration tolerance were studied under slow development of water stress. Substantial genetic variation was found for root penetration index, osmotic adjustment and dehydration tolerance among indica ecotypes from lowlands, and the study of several traditional varieties from uplands showed variation in root penetration index and related root traits. An indica accession, IR58821‐23‐B‐1‐2‐1 had a high root penetration index of 0.38. The accessions, IR61079‐33‐1‐2‐2‐3, IR62266‐42‐6‐2 and IR63919‐38‐B‐1 had high osmotic adjustment capacities (1.91, 1.90 and 1.78 MPa, respectively); IR61079‐33‐1‐2‐2‐3 also had high dehydration tolerance. Good osmotic adjustment and dehydration tolerance were associated with poor root system. The traditional varieties ‘Kallurundaikar’ and ‘Norungan’ had higher root penetration indices (0.46 and 0.43, respectively), than even the japonica accessions. The study identified indica accessions and traditional varieties with superior root‐ and shoot‐related drought resistance traits that could be used in breeding for drought resistance in rice.  相似文献   

14.
Recurrent drought periods of varying duration often cause extensive crop damage and affect wheat production in Southern Europe. This study compares biochemical and ultrastructural responses of four wheat (Triticum aestivum L.) cultivars to long‐term field drought, and their contribution to final grain yield. Gel electrophoresis and immunoblotting analyses combined with transmission electron microscopy and grain yield evaluation were employed to assess drought susceptibility of the wheat cultivars. Two of them behaved as drought‐tolerant, the other two presented as drought sensitive. Enhanced degradation of Rubisco large subunit (RLS), Rubisco small subunit (RSS) and Rubisco activase (RA) accompanied by an increased protease activity and reduced levels of heat shock proteins (HSP70) and dehydrins (DHNs) were associated with drought sensitivity. Drought tolerance coincided with relatively stable or increased HSP70 and DHN contents, and unchanged/higher levels of RLS, RSS and RA. Sensitive cultivars were more vulnerable to ultrastructural damages, showing obvious degradation of chloroplast membrane systems and depletion of leaf starch reserves. These drought responses affected yield potential, as tolerant cultivars gave higher yield under intense drought. Thus, our results provide additional insights into the complexity of plant drought responses, identifying multiple interacting traits that may serve as indirect selection criteria for wheat drought tolerance.  相似文献   

15.
Due to high costs of irrigation, limited availability of irrigation water in many locations and/or lack of irrigation capabilities, genetic improvement for drought tolerance is an effective method to reduce yield loss in soybean [Glycine max (L.) Merr.]. Slow wilting and minimal yield reduction under drought are important traits in evaluating drought tolerance. Two maturity group III soybean plant introductions (PIs, PI 567690 and PI 567731) and two elite cultivars (DKB38‐52 and Pana) were evaluated with and without irrigation on a sandy soil. Drought was imposed by withholding irrigation at full bloom and continued until moderate wilting was shown by the fast leaf wilting in the check cultivar, Pana. Then, irrigation was resumed until maturity. Genotypes were scored for leaf wilting during the stress period, and yields were assessed at the end of the growing season and used to calculate a drought index. Yields of the exotic PIs were lower than those of the checks under both drought and well‐watered conditions. However, the PIs exhibited significantly lower wilting and less yield loss under drought (higher drought index) than check cultivars. The two PIs may have useful genes to develop drought‐tolerant germplasm and cultivars and maybe useful in genetic and physiological studies to decipher mechanisms responsible for improving yield under limited water availability.  相似文献   

16.
Balanites aegyptiaca is a drought‐tolerant tree naturally distributed in Africa and has a high potential for biofuel production and livelihood. To understand the plant tolerance to drought stress, B. aegyptiaca plants collected from five provenances were subjected for 4 weeks to drought stress through different regimes of soil volumetric water content (VWC, i.e. 25% control, 15% as moderate and 5% as a severe drought stress) followed by 2‐week recovery. Morpho‐physiological responses as well as the changes in antioxidant defences under water stress and recovery were investigated. Drought stress significantly reduced plant biomass‐related parameters, stomatal conductance, quantum efficiency and increased leaf temperature. Each provenance showed specific patterns of stress response reactions that were detected in a cluster analysis. The large leaf area and a high level of lipid peroxidation in Cairo provenance increased its sensitivity to severe drought. For provenances El‐Kharga and Yemen, the highest tocopherol contents and the highest catalytic activities of ascorbate peroxidase (SOD), catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase (DHAR) were recorded. These traits contributed to the high drought tolerance of these two provenances in comparison with the other provenances. All plants recovered from stress and showed specifically increased activity of glutathione‐S‐transferase (GST) as a repair mechanism. Results showed that the drought tolerance level in B. aegyptiaca is provenance‐dependent.  相似文献   

17.
Faba bean (Vicia faba L.) is one of the most important and drought sensitive grain legumes. Drought stress is thus one of major constraints in global faba bean production. In this study, twenty local and exotic faba bean genotypes were characterized on physiological and molecular basis. Seeds of faba bean genotypes (six per pot) were sown in poly venyl chloride pots. After seedling emergence, soil moisture was maintained at 100%, 50% and 25% of field capacity designated as well watered, moderate drought and severe drought, respectively. Drought stress significantly influenced the leaf area, leaf temperature, stomatal conductance, relative leaf water contents, grain yield and water‐use efficiency. Faba bean genotypes also differed for the leaf area, leaf temperature, relative leaf water contents, grain yield and water‐use efficiency. Faba bean genotypes Kamline and L.4 were better equipped to curtail water loss, maintain tissue water status, produce stable grain yield and had better water‐use efficiency under mild and severe drought stress, and may be used in breeding programmes. Amplified fragment length polymorphism markers showed high potential in detecting polymorphism and estimating genetic diversity among faba bean genotypes. Unweighted pair group method with arithmetic mean cluster analysis of the genotypes illustrated considerable association between molecular diversity, genetic background and geographic origin. In crux, high polymorphic rate and polymorphism information content values, together with the low genetic similarity observed among tested genotypes suggests a high level of heterogeneity, which may be used in breeding programmes to assemble different drought tolerance mechanisms in one genotype.  相似文献   

18.
Drought tolerance is one of the most important objectives of sugar beet breeding programs in semi-arid regions, particularly during the last decade. Due to global climate changes and limitations of agricultural irrigation water, varieties with drought tolerance are taken into consideration in order to avoid yield losses due to drought. In this study, drought tolerance of 76 S1 lines (full-sib families) that had been extracted from a genetically broad base multigerm sugar beet open pollinated population, were examined. Test crosses were made between the lines as pollinators and a cytoplasmic male sterile (CMS) single cross. The consequent hybrids along with checks were evaluated during 2007 and 23 more tolerant hybrids during 2008, in two adjacent experiments under drought stress and non-stress conditions. Drought tolerance indices calculated based on sugar yield, such as mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI) were used to assess hybrids responses to drought. The results showed significant genetic differences for root yield and sugar yield under both conditions. Drought tolerance indices displayed significant genetic variability for sugar yield among the hybrids. Many hybrids were drought tolerant as compared with the original base population as indicated by their high STI. The estimates of heritability for sugar yield in stress and non-stress conditions were much close to each other (0.31 and 0.34, respectively). Whereas, for root yield the heritability estimate in stress condition (0.46) was relatively higher than that in non-stress condition (0.34). Significant differences were observed among the selected hybrids for root yield and sugar yield, indicating genotypic variability for pollinator lines derived from the population. There were no significant differences for sugar content. For increasing the drought tolerance potential in a breeding population and developing drought-tolerant varieties by male parent, the drought-tolerant lines could be used.  相似文献   

19.
Drought severely limits crop yield of peanut. Yet cultivars with enhanced root development enable the exploration of a greater volume of soil for water and nutrients, helping the plant survive. Root distribution patterns of three genotypes (ICGV 98305, ICGV 98324 and Tifton‐8) were compared when grown in well‐watered rhizoboxes and when grown in rhizoboxes where an early‐season drought was imposed using rain‐exclusion shelters. The treatments were arranged in a completely randomized design with three replications, and the experiment was conducted during two seasons at the Field Crop Research Station of Khon Kaen University, in Khon Kaen, Thailand. The root system of ICGV 98305, when grown under drought, had a significantly higher root length in the 30–110 cm deep soil layers and less roots in the 0–30 cm soil layers when under drought than when grown under well‐watered conditions. Roots of Tifton‐8 had the largest reductions in root length in upper soil layer and reduced in most soil layers. Tifton‐8 grown under drought was smaller than under well‐watered control for all root traits, showing negative response to drought. The peanut genotypes with high root traits in deeper soil layer under early‐season drought might contribute to drought avoidance mechanism.  相似文献   

20.
Drought tolerance is an increasingly important trait in common bean ( Phaseolus vulgaris L.) due to the reduction in water resources, a shift in production areas and increasing input costs. The objective of this study was to evaluate 29 genotypes for drought tolerance under drought stress (DS) and reduced stress treatments in Juana Diaz, Puerto Rico. The use of DS and reduced stress treatments facilitated the identification of drought tolerant germplasm that also had good yield potential under more optimal conditions. Based on the results of seed yield under DS and reduced stress conditions, and DS indices, including the geometric mean (GM), stress tolerance index (STI) and percent yield reduction (YR), genotypes were identified with greater yield potential under the tested environment. Based on average GM over the 2 years, the superior common bean genotypes identified were SEA 5, G 21212, A 686, SEN 21 and SER 21. These genotypes performed well in both years and under both treatment conditions and thus may serve as parents for DS improvement and genetic analysis.  相似文献   

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