共查询到20条相似文献,搜索用时 436 毫秒
1.
Water deficit is a major factor responsible for soybean yield gap in Southern Brazil and tends to increase under climate change. An alternative to reduce such gap is to identify soybean cultivars with traits associated to drought tolerance. Thus, the aim of this study was to assess soybean adaptive traits to water deficit that can improve yield under current and future climates, providing guidelines for soybean cultivar breeding in Southern Brazil. The following soybean traits were manipulated in the CSM-CROPGRO-Soybean crop model: deeper root depth in the soil profile; maximum fraction of shoot dry matter diverted to root growth under water stress; early reduction of transpiration under mild stress; transpiration limited as a function of vapor pressure deficit; N2 fixation drought tolerance; and sensitivity of grain filling period to water deficit. The yields were predicted for standard and altered traits using climate data for the current (1961–2014) and future (middle-century) scenarios. The traits with greater improvement in soybean yield were deeper rooting profile, with yield gains of ≈300 kg ha−1, followed by transpiration limited as a function of vapor pressure deficit and less drought-induced shortening of the grain filling period. The maximum fraction of shoot dry matter diverted to root and N2 fixation drought tolerance increased yield by less than 75 kg ha−1, while early reduction of transpiration resulted in a small area of country showing gains. When these traits were combined, the simulations resulted in higher yield gains than using any single trait. These results show that traits associated with deeper and greater root profile in the soil, reducing transpiration under water deficit more than photosynthesis, creating tolerance of nitrogen fixation to drought, and reducing sensitivity of grain filling period to water deficit should be included in new soybean cultivars to improve soybean drought tolerance in Southern Brazil. 相似文献
2.
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
3.
Plant breeding for drought-prone habitats envisages a favorable combination of grain yield and drought resistance. Though
several components enhancing drought resistance have been identified in rice,their association with grain yield, under low-moisture
stress, has been established in very few instances. We attempt to study the associations between rice grain yield and root
system parameters both at phenotypic and genotypic levels. The doubled haploid population of IR64/Azucena was evaluated for
root related traits at peak vegetative stage and grain yield related traits under both low-moisture stress and non stress
conditions. ‘Mean environment’ was computed for yield related traits. Correlation and QTL mapping was attempted to find out
the associations. The correlation between maximum root length and grain yield was positive under stress and negative in non
stress. Genotypes with thicker and deeper roots, manifested higher biomass and grain yield under stress. Only one QTL found
to increase days to flowering in non stress was also found to influence root volume and dry weight negatively under stress.
The study suggests that loci enhancing grain yield and related traits were not pleiotropic with loci for desirable root morphological
traits studied under low-moisture stress at vegetative stage, in the genetic material used in the study. It is thus possible
to combine higher grain yield and desirable root morphological traits, favorably, to enhance productivity of rice under low-moisture
stress. In rainfed ecologies, where deep roots contribute to enhanced drought resistance in rice, the results indicate the
possibility of combining drought resistance with higher levels of grain yield.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Apurba Kanti Choudhury Abdul Karim Moynul Haque Qazi Abdul Khaliq Jalal Uddin Ahmed Mofazzal Hossain 《Journal of Crop Science and Biotechnology》2011,14(1):17-24
Seven genotypes of French bean (Phaseolus vulgaris L.) were evaluated under semi-controlled conditions at the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh
to analyze genotypic variability in leaf water status under water stress. The plants were grown under two moisture regimes,
viz. 80% field capacity (FC) and 50% FC throughout the growing season. The genotypes showed significant variation in water relation
traits. Genotypes BB24 and BB43 maintained higher relative water content (RWC), but lower turgid weight/dry weight ratio (TW/DW)
and water uptake capacity (WUC). When drought susceptibility index (DSI) among the genotypes was considered, BB24 was found
the most tolerant to drought and BB04 was the most susceptible one. A close positive relationship between leaf TW/DW and DSI
under drought was recorded (R
2 = 0.627). Leaf TW/DW was decreased considerably due to water stress by 10% in genotype BB24 followed by BB43 (13%), and both
BARI bushbean-2 and BB04 (19%). Stomatal aperture and whole plant transpiration rate were found minimal in the BB24 and BB43
compared to that of BB04 and BARI bushbean-2. Considering these water relation traits, genotypes BB24 and BB43 may be considered
as relatively tolerant to tissue dehydration. The study also revealed that the TW/DW, WUC, stomatal aperture, and whole plant
transpiration rate was negatively and significantly associated with yield; however, the RWC was positively correlated with
yield under water stress conditions. 相似文献
5.
Yoseph Beyene Stephen Mugo Kassa Semagn Godfrey Asea Walter Trevisan Amsal Tarekegne Tadele Tefera James Gethi Barnabas Kiula John Gakunga Haron Karaya Andrew Chavangi 《Euphytica》2013,192(3):379-392
In contrast to conventional inbreeding that takes up to seven generations to develop inbred lines, the doubled haploid (DH) technology allows production of inbred lines in two generations. The objectives of the present study were to: (a) evaluate testcross performance of 45 doubled haploid lines under drought stress and non-stress conditions (b) estimate heritabilities for grain yield and other traits and (c) to assess the genetic distance and relationship among the DH lines using 163,080 SNPs generated using genotyping-by-sequencing (GBS). The 45 hybrid and five checks were evaluated using a 10 × 5 alpha lattice in six drought stress and nine well-watered environments in Kenya, Uganda, and Tanzania. Differences in trait means between the drought stress and well-watered conditions were significant for all measured traits except for anthesis date. Genetic variances for grain yield, grain moisture, plant height and ear height were high under well-watered environments while genetic variance for anthesis date, root lodging and stalk lodging were high under drought stress environments. Combined analyses across drought stress and well-watered environments showed that ten top hybrids produced 1.6–2.2 t/ha grain yield under well-watered condition and 1–1.4 t/ha under drought stress condition higher than the mean of the commercial checks. Genetic distance between pairwise comparisons of the 38 of the 45 DH lines ranged from 0.07 to 0.48, and the overall average distance was 0.36. Both cluster and principal coordinate analysis using the genetic distance matrix calculated from 163,080 SNPs showed two major groups and the patterns of group was in agreement with their pedigree. Thirteen (13) of the best hybrids are currently in National Performance Trials testing, an important step towards commercialization in Kenya, Tanzania and Uganda. 相似文献
6.
Genetic variation in salt tolerance at the seedling stage in an interspecific backcross inbred line population of cultivated tetraploid cotton 总被引:1,自引:0,他引:1
Rashmi Sharma Tiwari Geno A. Picchioni Robert L. Steiner Don C. Jones S. E. Hughs Jinfa Zhang 《Euphytica》2013,194(1):1-11
Soil salinity reduces cotton growth, yield, and fiber quality and has become a serious problem in the arid southwestern region of the Unites States. Development and planting of salt-tolerant cultivars could ameliorate the deleterious effects. The objective of this study was to assess the genetic variation of salt tolerance and identify salt tolerant genotypes in a backcross inbred line (BIL) population of 142 lines from a cross of Upland (Gossypium hirsutum) × Pima cotton (G. barbadense) at the seedling growth stage. As compared with the non-saline (control) conditions, seedlings under the salinity stress (200 mM NaCl) showed a significant reduction in all the plant growth characteristics measured, as expected. Even though the two parents did not differ in salt response as measured by percent reduction, significant genotype variations in the BIL population were detected for all traits except for leaf number. Based on percent reduction of the traits measured, several BILs were more salt tolerant than both parents. The results indicate that transgressive segregation occurred during the process of backcrossing and selfing even though both parents were not salt tolerant during seedling growth. Coefficients of correlation between all the traits were significantly positive, indicating an association between the traits measured. The estimates of broad-sense heritability were 0.69, 0.46, 0.47, 0.43, and 0.49 for plant height, fresh weight of shoot and root, and dry weight of shoot and root, respectively, indicating that salt tolerance during cotton seedling growth is moderately heritable and environmental variation plays an equally important role. The overall results demonstrate that backcrossing followed by repeated self-pollination is a successful strategy to enhance salt tolerance at the seedling stage by transferring genetic factors from Pima to Upland cotton. 相似文献
7.
Adel H. Abdel-Ghani Bharath Kumar Jenaro Reyes-Matamoros Pedro J. Gonzalez-Portilla Constantin Jansen Juan Pablo San Martin Michael Lee Thomas L��bberstedt 《Euphytica》2013,189(1):123-133
Genotypes with better root development have good nutrient acquisition capacity and may yield better under limited nitrogen (N) conditions and consequently can help reduce the N fertilization rate and hence mitigate some economic and ecological problems. This study focused on the genotypic variation among diverse maize inbred lines for seedling and adult plant traits under contrasting N levels. Seventy-four lines were screened under high and low N levels in a climate chamber and in the field. High phenotypic diversity was observed for seedling and adult plant traits together with moderate to high broad-sense heritability estimates. Seedling total root length and root dry weight were significantly correlated with other root traits in maize. Of the adult plant traits evaluated in the field, the anthesis-silking interval and the leaf chlorophyll contents were significantly correlated with grain yield under both low and high N levels. In one location, the seminal root length was correlated with grain yield both under low and high N levels and the root dry weight was correlated with grain yield under high N. Selection indices based on secondary root traits along with grain yield could lead to an increase in selection efficiency for grain yield under N stress condition. By identifying lines with better root development, particularly lines with longer SRL, it may be possible to select inbred lines with higher grain yield particularly under low N condition. 相似文献
8.
Pooran M. Gaur Srinivasan Samineni Mahendar Thudi Shailesh Tripathi Sobhan B. Sajja Veera Jayalakshmi Durdundappa M. Mannur Adiveppa G. Vijayakumar Nadigatla V. P. R. Ganga Rao Chris Ojiewo Asnake Fikre Paul Kimurto Robert O. Kileo Nigusie Girma Sushil K. Chaturvedi Rajeev K. Varshney Girish P. Dixit 《Plant Breeding》2019,138(4):389-400
Chickpea (Cicer arietinum L.) is a dry season food legume largely grown on residual soil moisture after the rainy season. The crop often experiences moisture stress towards end of the crop season (terminal drought). The crop may also face heat stress at the reproductive stage if sowing is delayed. The breeding approaches for improving adaptation to these stresses include the development of varieties with early maturity and enhanced abiotic stress tolerance. Several varieties with improved drought tolerance have been developed by selecting for grain yield under moisture stress conditions. Similarly, selection for pod set in the crop subjected to heat stress during reproductive stage has helped in the development of heat‐tolerant varieties. A genomic region, called QTL‐hotspot, controlling several drought tolerance‐related traits has been introgressed into several popular cultivars using marker‐assisted backcrossing (MABC), and introgression lines giving significantly higher yield than the popular cultivars have been identified. Multiparent advanced generation intercross (MAGIC) approach has been found promising in enhancing genetic recombination and developing lines with enhanced tolerance to terminal drought and heat stresses. 相似文献
9.
M. R. Abenavoli M. Leone F. Sunseri M. Bacchi A. Sorgonà 《Journal of Agronomy and Crop Science》2016,202(1):1-12
Common bean (Phaseolus vulgaris) is cultivated throughout Latin America and Africa, and for the European community, in Italy and Spain, areas are mainly subjected to drought stress which is predict to worsen by regional climatic models. The aims of this work were to identify the drought‐tolerant and drought‐sensitive bean landraces using drought tolerance and phenotypic plasticity indexes and to dissect the root morphological and 2D‐architecture traits related to drought tolerance. Thirty‐one landraces from diverse gene pools and areas of the Calabria region (South Italy), with different habits and morphological traits, were screened for drought tolerance in a hydroponic system. Root phenotyping was conducted by image analysis. Drought tolerance screening identified two landraces as drought tolerant and sensitive, respectively. Under drought stress, the drought‐tolerant landrace exhibited several interesting root traits such as a higher root length, surface area and, above all, the fineness of the whole root systems and, with emphasis, of the higher order roots. Drought stress induced plastic root responses in both bean landraces but with contrasting patterns. The drought‐tolerant landrace exhibited a dimorphic‐rooted strategy, which could be included in future utility for bean breeding programmes in drought‐prone environments. 相似文献
10.
Effect of Water Stress on Physiological Attributes and their Relationship with Growth and Yield of Wheat Cultivars at Different Stages 总被引:1,自引:0,他引:1
The effects of water stress on physiological attributes of drought‐sensitive (Kalyansona) and drought‐tolerant (C‐306) wheat cultivars were studied in a pot experiment. Water stress was imposed by withholding irrigation at boot and anthesis stages. Leaf water potential, leaf osmotic potential and leaf turgor potential (measured with pressure chamber and osmometer), as well as leaf diffusive resistance, leaf transpiration rate and leaf‐to‐air transpiration gradient (measured with a steady‐state porometer) were measured diurnally. Growth and yield parameters were recorded after harvesting of the crop. Triplicate data were analysed using a completely randomized design and correlations amongst these parameters were computed. Water stress was found to reduce diurnal leaf water potential and leaf osmotic potential in both the genotypes but leaf osmotic potential was significantly higher in the drought‐tolerant cultivar C‐306 than in the drought‐sensitive cultivar Kalyansona. Positive turgor was recorded in both the genotypes under water stress and non‐stress conditions. Water‐stressed plants showed significantly lower turgor potential than control plants. In diurnal observations, water‐stressed plants exhibited significantly higher leaf diffusive resistance in both genotypes at both stages. The diffusive resistance of C‐306 was predominantly higher than that of Kalyansona. Water stress decreased leaf transpiration rate at both stages but the reduction was higher at the anthesis stage. The leaf‐to‐air temperature gradient was much higher in C‐306 than in Kalyansona at the boot stage but at the anthesis stage genotypic variation was non‐significant. The capacity to maintain cooler foliage was lower at the anthesis stage than at the boot stage in both the cultivars. Shoot dry weight, number of grains, test weight, grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage, while imposition of water stress at the boot stage caused a greater reduction in plant height and number of tillers. Similarly, water stress caused a smaller reduction in growth, yield and yield attributes in C‐306 than in Kalyansona. In general, the correlation coefficient of grain and biological yield with water potential and its components was positive and highly significant. Similarly, turgor potential was also correlated positively and significantly with grain yield at both the stages, but with biological yield it was significant only at the anthesis stage. A negative and significant correlation was obtained for diffusive resistance and leaf‐to‐air temperature gradient with grain yield at the boot and anthesis stages. The rate of transpiration was also positively and significantly correlated to grain and biological yields at both the stages. Amongst the yield attributes, number of leaves and number of tillers were positively correlated at the anthesis stage, whereas leaf area and shoot dry weight were significantly correlated with grain and biological yields at both the stages. 相似文献
11.
Seyyed Gholam Reza Moosavi Seyyed Hamid Reza Ramazani Saeid Sadeghzadeh Hemayati Hamid Gholizade 《Journal of Crop Science and Biotechnology》2017,20(3):167-174
To study the effects of different levels of drought stress on root yield and some morpho-physiological traits of sugar beet genotypes, a study was conducted in the research farm of Islamic Azad University of Birjand, Iran in 2013 as strip-split plot experiments based on randomized complete block design. Different levels of drought stress were considered as vertical factor in three levels including normal irrigation, moderate stress, and severe stress. Horizontal factor was assigned to five varieties of sugar beet. Drought stress had a significant effect on root dry weight, total dry weight, root yield, and leaf temperature at 1% probability level and on leaf dry weight, crown dry weight, and harvest index at 5% probability level. Drought stress had an adverse effect on root yield of investigated genotypes of sugar beet. Under normal conditions, the mean of root yield was higher than middle and severe drought stress. Different investigated genotypes of sugar beet responded to drought stress based on their yield potential. The highest positive correlation of root yield was observed with root dry weight (r=0.977**). Stepwise regression analysis and path coefficient analysis showed that root dry weight and petiole dry weight are the most important traits that can affect root yield of sugar beet under drought stress and can used as selection criteria in investigated cultivars of sugar beet. Finally, 7221 genotypes can be considered as tolerant genotypes in the next studies. In comparison, Jolgeh cultivar (as susceptible control) yielded well in areas with normal irrigation, but under moderate and severely stresses its root yield was reduced. 相似文献
12.
Md. Hasanuzzaman Lana Shabala Timothy J. Brodribb Meixue Zhou Sergey Shabala 《Journal of Agronomy and Crop Science》2019,205(2):129-140
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
13.
Three rice varieties, viz. ADT 31 (drought tolerant) CO 41 (upland) and IR 50 (drought susceptible), were employed to study their rooting patterns under different water regimes. ADT 31 had better root penetration and distribution under water stress situation compared to others. The values on root weight also established a similar trend. Isotopic studies with 32 P also provided evidence in this regard wherein the variety ADT 31 showed its adaptiveness to drought. Marginal reduction in plant height, less tiller production and leaf area reductions were noted in ADT 31 and CO 41 under decreasing soil moisture which showed its ability to cope with the water stress situation. Though IR 50 recorded higher grain yield at normal irrigation, a drastic reduction was noted under extreme water deficit. But ADT 31 recorded consistent values in all situations with slight marginal reduction which evidently proved the interdependent nature of rooting pattern and its influence on productivity. 相似文献
14.
Akkareddy Srividhya Lakshminarayana R. Vemireddy Sakile Sridhar Mudduluru Jayaprada Puram V. Ramanarao Arremsetty S. Hariprasad Hariprasad K. Reddy Ghanta Anuradha Ebrahimali Siddiq 《Journal of Crop Science and Biotechnology》2011,14(1):45-56
Moisture stress is the major constraint to rice production and its stability in rainfed, mainly irrigated, and aerobic environments.
Identification of genomic regions conferring tolerance to stress would improve our understanding of the genetics of stress
response and result in the development of drought tolerant cultivars. In the present study, quantitative trait loci for drought
response related traits and as well as grain yield were identified using a set of 140 recombinant inbred lines derived from
a cross between the popular high-yielding variety, IR64 and the landrace, INRC10192. A total of 36 QTL were identified for
grain yield and its components under control and stress conditions. Strikingly, a QTL cluster flanked by the markers RM38
and RM331 on chromosome 8 was found to be associated with grain yield, plant height, no. of productive tillers, chaffy grains,
and spikelet fertility on secondary rachis and biomass under stress treatment. The genomic regions associated with these QTL
under drought stress will be useful for the development of marker-based breeding for drought tolerant, high-yielding varieties
suited to drought-prone areas. 相似文献
15.
Bin Peng Xiuwei Liu Xuejun Dong Qingwu Xue Clark B. Neely Thomas Marek Amir M. H. Ibrahim Guorong Zhang Daniel I. Leskovar Jackie C. Rudd 《Journal of Agronomy and Crop Science》2019,205(6):571-585
Roots strongly influence the growth and yield of field crops. We characterized root morphological traits of 10 winter wheat varieties in order to determine the extent they were influenced by the environments and impacted grain yield under two irrigation regimes at Bushland (a cooler, drier site with clay loam soil) and Uvalde (a warmer, wetter site with clay soil) in Texas, USA, from 2015 to 2017. Major root traits, including root diameter, specific root length (SRL), root surface area (SSA), tissue mass density (TMD), root length density (RLD), and root weight density, were measured and related to one another and to grain yield. RLD of wheat decreased but SRL and SSA increased with soil depth. Irrigation was second to environment in affecting root traits. Compared with Uvalde, the environment of Bushland promoted deeper root growth, higher TMD, but reduced SRL and SSA. Water deficit inhibited RLD and root: shoot ratio at Bushland, but moderately promoted them at Uvalde. Both SRL and RLD were positively associated with grain yield, with the former relation stronger under drought. The dichotomy of “conservative” versus “acquisitive” root strategy partially explained the variations of root traits of winter wheat in contrasting environments. 相似文献
16.
Shiva Bakhshandeh Paola E. Corneo Liming Yin Feike A. Dijkstra 《Journal of Agronomy and Crop Science》2019,205(2):157-167
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
17.
M. van Ginkel D.S. Calhoun G. Gebeyehu A. Miranda C. Tian-you R. Pargas Lara R.M. Trethowan K. Sayre J. Crossa S. Rajaram 《Euphytica》1998,100(1-3):109-121
Bread wheats (Triticum aestivum L.) were evaluated for plant characteristics contributing to grain yield and plant adaptation
under various drought patterns. The usefulness of these traits as explicit selection criteria in developing drought tolerant
wheat varieties was investigated in three experiments. Cultivars from four germplasm groups, representing the four relevant
major and distinct global wheat growing environments, were grown under the respective simulated early, late, continuous and
no drought conditions by manipulating irrigation in north western Mexico. Additionally, 560 advanced lines from the CIMMYT
breeding program were grown under late drought conditions, and 16 randomly selected advanced genotypes were studied in more
detail under late and no drought conditions. In these three studies, the association between yield in drought-stressed environments
and yield in non drought-stressed environments was interpreted to reflect genotypic high yield potential, mainly by way of
high biomass development. However, yield potential only partly explained the superior performance under drought. For each
pattern of drought stress, particular and often different plant traits were identified that further contributed specific adaptation
to the distinct drought stress conditions. Knowledge of these traits will be useful for developing CIMMYT germplasm for specific
drought-stressed areas. Ultimately, these studies demonstrate that both yield potential and specific adaptation traits are
useful criteria in breeding for drought environments, and should be combined to achieve optimum performance and adaptation
to drought stress.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
After the evaluation of numerous accessions of primitive wheats for yield components and morphophysiological traits related
to drought tolerance (e.g., maintenance of high relative water content, RWC; photochemical quenching of chlorophyll fluorescence,
qQ; and chlorophyll loss, chl, under moisture stress conditions), several accessions belonging to three species (Triticum
dicoccum, T. polonicum, and T. carthlicum) were crossed with the improved durum wheat varieties Cham 1 and Om Rabi 5. A direct
selection (F2 progeny) for yield and an indirect physiological trait were applied on interspecific T. durum x T. dicoccum, T. durum x T.
polonicum, and T. durum x T. carthlicum populations. Divergent selection was applied to validate the possible use of morphophysiological
traits (root parameters, RWC, photochemical quenching, proline content, and carbon isotope discrimination) in selection, and
to evaluate the resulting effects on yield. Heritability and selection response of these traits has been evaluated, and the
impact of divergent selection for morphological and agronomic characters was studied under field conditions. The divergent
populations were evaluated under different environmental conditions in France, Syria, and Yemen. Selection for morphophysiological
traits related to moisture stress, such as root parameters, RWC and carbon isotope discrimination was possible due to high
h2 values and effective, resulting in high genetic gains. However, the effect of selection for these traits on yield stability
needs to be further studied. Furthermore, a modified bulk method (F2 'progeny method') was developed. Direct selection for grain yield per plant in F2 was carried out and yield per line in F3 was evaluated under contrasting environmental conditions in France, Syria, and Tunisia. Results revealed that some F3 lines were higher yielding than the improved durum wheat varieties Cham 1 and Om Rabi 5 under both stressed (Aleppo) and
favourable (Montpellier) environmental conditions. Lines were evaluated in preliminary yield trials at Montpellier (France),
Aleppo (Syria), and Constantine (Algeria). Results indicated that the use of related species combined with the use of the
modified bulk breeding method is promising not only for increasing durum wheat yield in drought prone environments, but also
for improving durum wheat yield stability across contrasting environments. Results of both breeding strategies are presented,
and the potential advantages of using related tetraploid species in durum wheat breeding for drought tolerance are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
The growth behaviour of Dekama (drought tolerant) and Kufri Jyoti (drought susceptible) was studied using potted plants maintained at well watered condition and water deficit condition respectively. Periodic harvestings were done starting from 50 days after planting till maturity. Recordings of plant height, leaf area, dry weights of different plant parts, the proportion of thinner and thicker roots, stomatal conductance and water saturation deficit were obtained. The plant height, leaf area and dry weight of shoot decreased to nearly the same extent in both the cultivars under stress. The stomatal conductance decreased by 61.7 % in Dekama and by 64 % in Kufri Jyoti due to water stress. Water saturation deficit increased by about 80 % in both the cultivars. The ratios of root to shoot and that of thinner to thicker root increased due to stress in both cultivars and this increase was 85 % and 71 % in Dekama and 64 % and 19 % in Kufri Jyoti respectively. The distribution of dry matter to leaf, stem, root were more at the expense of tuber under stress conditions in both cultivars. However, the tolerant cultivar Dekama got adjusted to the stress condition, with more dry matter partitioned to tubers in the last two samplings. The study points out the factors responsible for better drought tolerance of Dekama compared to Kufri Jyoti and the possible physiological traits useful for selecting drought tolerant cultivars. 相似文献
20.
M. Subashri S. Robin K. K. Vinod S. Rajeswari K. Mohanasundaram T. S. Raveendran 《Euphytica》2009,166(2):291-305
Drought resistance is becoming an indispensable character for rice improvement due to the dwindling global water resources.
Genetic improvement for drought resistance is achieved through physiological dissection and genetic analysis of independent
component traits associated with crop productivity under stress. A subset mapping population of 93 near flowering recombinant
inbred lines with uniform phenology was constituted for genetic analysis of reproductive stage drought resistance. The population
was phenotyped for 22 physio-morphological traits under two contrasting water regimes imposed at reproductive stage. Broad
sense heritabilities of morphological traits were lower under stress than irrigated. Predominant association of plant height,
panicle exsertion and harvest index with grain yield were observed under stress. The sustenance of panicle exsertion through
maintaining growth during moisture stress was found as a significant trait associated with the grain yield through minimizing
spikelet sterility. Selective genotyping was carried out with 23 polymorphic microsatellite markers of the established target
genomic regions for drought resistance. The study validated the association of a QTL region on the long arm of chromosome
1 with plant height, panicle length, panicle exsertion, biological yield and stomatal conductance under stress. This region,
flanked by markers RM246 and RM315, was known to possess the semi-dwarf gene, sd-1. Role of another major interval lying between RM256 and RM149 on chromosome 8 in defining the drought resistance could be
established through identification of QTLs associated with leaf rolling, panicle exsertion, plant height, panicle length,
senescence and biological yield under moisture stress condition. Few other QTLs were also identified. 相似文献