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1.
Mid‐season drought is a factor frequently limiting crop production in the moist to dry savannah zones of the tropical and subtropical regions of the world. Ten cowpea genotypes were subjected to a cycle of drought at flowering followed by re‐watering to study variation in drought performance and recovery. Drought caused a reduction in leaf assimilation rate, transpiration rate and stomatal conductance with genotypic variances of 75.4, 57.9, and 83.3 %, respectively. Only genotypic variance in stomatal conductance increased appreciably under drought. Reductions in leaf water potential as a consequence of drought positively correlated with a decline in assimilation rate, which was associated with stomatal closure. One week after re‐watering, the three gas exchange parameters of stressed plants recovered fully and attained values 10–30 % higher than the well‐watered plants with increased genotypic variability. Reductions in the total dry matter during the drought interval varied from 11 to 50 % among genotypes, but were of minor importance for the total dry matter at maturity. After stress, the gain in dry matter varied considerably among the stressed genotypes, with stressed plants showing higher gain than the unstressed plants during this interval. This was associated with increased availability of assimilates due to enhanced green leaf area duration after stress release. Variability in drought recovery among genotypes was found, and appears to be more important for final yield than responses during drought.  相似文献   

2.
In semi‐arid regions, particularly in the Sahel, water and high‐temperature stress are serious constraints for groundnut production. Understanding of combined effects of heat and drought on physiological traits, yield and its attributes is of special significance for improving groundnut productivity. Two hundred and sixty‐eight groundnut genotypes were evaluated in four trials under both intermittent drought and fully irrigated conditions, two of the trial being exposed to moderate temperature, while the two other trials were exposed to high temperature. The objectives were to analyse the component of the genetic variance and their interactions with water treatment, year and environment (temperature) for agronomic characteristics, to select genotypes with high pod yield under hot‐ and moderate‐temperature conditions, or both, and to identify traits conferring heat and/or drought tolerance. Strong effects of water treatment (Trt), genotype (G) and genotype‐by‐treatment (GxTrt) interaction were observed for pod yield (Py), haulm yield (Hy) and harvest index (HI). The pod yield decrease caused by drought stress was 72 % at high temperature and 55 % at moderate temperature. Pod yield under well‐watered (WW) conditions did not decrease under high‐temperature conditions. Haulm yield decrease caused by water stress (WS) was 34 % at high temperature and 42 % under moderate temperature. Haulm yield tended to increase under high temperature, especially in one season. A significant year effect and genotype‐by‐environment interaction (GxE) effect were also observed for the three traits under WW and WS treatments. The GGE biplots confirmed these large interactions and indicated that high yielding genotypes under moderate temperature were different to those at high temperature. However, several genotypes with relatively high yield across years and temperature environments could be identified under both WW and WS conditions. Correlation analysis between pod weight and traits measured during plant growth showed that the partition rate, that is, the proportion of dry matter partitioned into pods, was contributing in heat and drought tolerance and could be a reliable selection criterion for groundnut breeding programme. Groundnut sensitivity to high‐temperature stress was in part related to the sensitivity of reproduction.  相似文献   

3.
Limited knowledge about genetic and physiological traits associated with drought and low temperature stresses and narrow genetic diversity in Upland cotton (Gossypium hirsutum L.) are serious impediments in its genetic improvement. The objectives of this research were to determine the genetic and physiological traits associated with drought and low temperature effects and to identify chromosomal effects on these traits using chromosome substitution (CS) lines from three alien species of Gossypium, G. barbadense, G. tomentosum, and G. mustelinum, respectively. Two experiments were conducted to study low temperature and drought stress effects during seedling emergence and early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22 °C) and low (22/14 °C) temperature conditions under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water (soil moisture content of 0.167 m3 m?3) and in drought (soil moisture content 0.105 m3 m?3) conditions under optimum temperature conditions. Above- and below-ground growth traits including several root traits of the CS lines were assessed at 25 days after sowing. The findings suggest which substituted chromosome or chromosome segment from the alien species likely harbors one or more genes for higher and lower tolerance to low temperature, respectively. CS-T04 and CSB08sh showed higher and lower tolerance to low temperature, respectively and CS-T04 and CS-B22sh showed higher and lower tolerance, respectively, to drought. CS lines are valuable analytical tool and useful genetic resources for targeted exploitation of beneficial genes for drought and low temperature stresses in Upland cotton.  相似文献   

4.
Drought tolerance as such is often not considered to be an independent trait by plant breeders. The objective of this study was to evaluate eight drought tolerance indices, namely stress susceptibility index (SSI), yield stability index (YSI), yield reduction ratio (Yr), yield index (YI), tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI) in upland cotton (G. hirsutum L.) genotypes. For this purpose, 16 genotypes were sampled during the 2013-2014 growing seasons under both normal and drought-stress field conditions at the Main Cotton Research Station of Navsari Agricultural University, Surat, India. The drought tolerance indices were calculated based on seed cotton yield under drought stress and non-stress conditions. Mean comparison of drought tolerance indices and seed cotton yield validated the significant influences of drought stress on yield as well as significant differences among genotypes. Results of calculated correlation coefficients and multivariate analyses showed that GMP, MP and STI indices were able to discriminate drought-sensitive and tolerant genotypes. Cluster analysis using the drought-tolerance indices divided the 16 genotypes into tolerant and susceptible groups. Two genotypes, G.Cot.16 × H-1353/10 and H-1353/10 × G.Cot.16 gave good yield response under drought conditions leading to their stability during water stress conditions. Based on multivariate analyses using the indices individually or in combinations, it was possible to identify the most yield-stable genotypes across the environments. Overall, we concluded that GMP, MP and STI indices can be efficiently exploited not only for screening drought tolerance but also to identify superior genotypessuitable for both stress and non-stress field conditions.  相似文献   

5.
Modification of source–sink ratios in tropical maize through detasseling is an ancestral agronomical practice used for increasing yields under stressful conditions. However, the mechanisms behind such effect are not well understood given the difficulties to determine physiological processes such as photosynthesis and whole‐plant transpiration in the field. We have tested the potential ability of kernel δ 18O to assess differences in grain yield (GY ) through changes in plant transpiration caused by the modification of water availability and source–sink modification treatments, (including removal of the tassel and different numbers of leaves) in three tropical maize hybrids differing in drought tolerance. Drought‐tolerant genotypes displayed higher yields and lower kernel δ 18O values than the drought‐susceptible genotype under both well‐watered (WW ) and water‐stressed (WS ) conditions. Detasseling caused a positive increase in GY under well‐watered (up to 8%) and water‐deficit conditions (up to 36%). Reduction in leaf area (source) through defoliation treatments caused a large impact on GY showing a trade‐off between maintaining a photosynthetic versus transpiring leaf area. Thus, while a reasonable reduction in leaf area significantly improved plant water availability (as shown by lower kernel δ 18O values) and consequently GY under water deficit (up to 40%), it caused a maximum reduction of 25% in GY under well‐watered conditions. Variations in GY were significantly (p  <  .05) correlated with changes in δ 18O under both well‐watered (r  =  ?.67) and WS conditions (r  =  .75 and .82). Our results also reinforce the utility of δ 18O measured in mature kernels as a powerful ecophysiological tool for assessing genotypic differences in apical dominance, transpiration and yield under both WW and WS conditions in tropical maize.  相似文献   

6.
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   

7.
Seed yield in chickpea (Cicer arietinum L.) is substantially increased by advancing sowing date from the traditional spring to early winter at low to medium elevation areas around the Mediterranean Sea. This shift, however, increases the probability of the exposure to subzero temperatures as low as -10 °C for up to 60 days in a year. These low temperatures often reduce seed yield of cold-susceptible cultivars. Yield losses from cold were estimated in two experiments conducted at Tel Hadya, Syria. In experiment 1, of 96 genotypes sown on nine dates ranging from autumn to spring during the 1981–82 season, those lacking tolerance to cold were killed and produced no yield in autumn sowing, whereas lines with cold tolerance produced nearly 4 t/ha which corresponds to a four-fold increase over spring sowing. Moderately cold-tolerant genotypes sown during early winter produced substantially more seed yield than the normal spring-sown crop. Seedlings were more cold tolerant than the plants in early or late vegetative stages. In experiment 2, in which yield loss due to cold in the field was estimated in 12 yield trials comprising 288 newly bred lines in the 1989–90 season, the regression of cold susceptibility on seed yield in each of the trials was highly significant and negative. On average, winter-sown trials produced 67 % more seed yield than spring-sown trials, but 125 out of 288 genotypes produced yield more than double in winter sowing. Early maturing lines suffered severe cold damage and many lines produced no seed.  相似文献   

8.
The leaf subtending to a cotton boll (LSCB) is vital to boll development and biomass, but few studies have examined the effects of drought on the source capacity of LSCBs on different fruiting branches (FBs). To investigate the response of LSCB photosynthesis on different FBs and the relationship of boll biomass to drought, a drought experiment was performed with three treatments: well‐watered (WW, soil water relative content [SRWC] 75 ± 5%), mild drought (MD, SRWC 60 ± 5%), and severe drought (SD, SRWC 45 ± 5%). Despite photosynthetic active radiation increasing under drought conditions, the pre‐dawn leaf water potential, net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and maximum quantum yield in PSII (Fv/Fm) under MD and SD significantly decreased when compared with WW, with a more pronounced decrease observed on upper FBs. Additionally, the maximum sucrose and hexose levels in LSCBs increased under drought conditions, whereas the maximum starch content decreased on FB10–11, but showed a varied trend on FB2–3 and FB6–7. Although carbohydrate levels in the LSCBs increased, biomass per cotton boll decreased. More importantly, the ratio of cotton boll biomass was significantly correlated to the maximum sucrose content ratio on each FB, indicating that sucrose allocation was important to cotton boll biomass. Cotton boll biomass notably decreased on upper FBs, but was maintained on lower FBs, indicating that drought promoted carbon allocation in older bolls. Thus, LSCBs and cotton bolls on upper FBs were more affected under drought conditions due to decreased photosynthesis and carbohydrate allocation.  相似文献   

9.
Development of rapid and inexpensive screening tools for heat and drought stress tolerance is needed and will be helpful in cotton breeding programs and selecting cultivars for a niche environment. In this study, several pollen-based traits at optimum and high temperatures and physiological parameters measured during the boll-filling period were used to evaluate variability among the cultivars for heat and drought stresses. Principal component analysis and drought stress response index methods were used to categorize cotton cultivars into three heat and drought tolerant clusters. Based on the combined analysis, PX532211WRF has been identified as heat- and drought-tolerant, and would be expected to perform better under both heat- and drought-stressed environments. A poor correlation between reproductive and physiological indices indicates that screening breeders have to use different traits to screen cultivars for reproductive and vegetative tolerance. Identified traits could serve as valuable screening tools in cotton breeding programs aimed at developing genotypes to a changing climate. Moreover, cultivar-dependent relative scores will aid in the identification of cultivars best suited to niche environments to alleviate the influences of abiotic stresses at both vegetative and reproductive stages.  相似文献   

10.
Even in the temperate climates of Europe, increasing early season drought and rising air temperature are presenting new challenges to farmers and wheat breeders. Sixteen winter wheat (Triticum aestivum L.) genotypes consisting of three hybrids, six line cultivars and two breeding lines from Germany as well as five line cultivars from France, Austria, Slovakia, Hungary and the Ukraine (referred to as “exotic” lines) have been included in this study. The genetic materials were evaluated over three growing seasons under a range of soil moisture regimes at the three North German sites Braunschweig (irrigated and drought‐stressed), Warmse (rainfed) and Söllingen (rainfed). The average grain yields in the twelve growth environments (water regime × season combinations) ranged from 6.1 to 13.5 t ha?1. The exotic lines showed little evidence of specific phenological adaptation to drought although they are frequently faced with water scarcity in their countries of origin. The hybrids and German lines exhibited higher regression coefficients (bi) to environmental means than the exotic lines, indicating particular adaptation to favourable growing conditions. The phenotypical correlations of grain yield between the various environments were high, ranging for instance from 0.6 to 0.8 for the irrigated and drought‐stressed environments at Braunschweig. It is thus expected that in the foreseeable future continued selection aiming at high yield potential will suffice as a means to counter the expected increase in droughts.  相似文献   

11.
Canopy temperature has been recognised as an indicator of crop water status and may thus be a useful secondary trait in selecting for yield under dry conditions. The aim of this study was to test the suitability of canopy temperature depression (CTD = Tair ? Tcanopy) in a temperate climate with winter rye, by means of three infrared (IR) temperature measuring devices. In the years 2011 and 2012, 16 winter rye genotypes were examined under drought stress conditions in a rainout shelter and under well‐watered conditions. In each year, the CTD was determined several times during the growth period using two IR thermometers and an IR camera. By means of CTD, it was possible to detect drought stress and to differentiate between water regimes. The three measurement devices showed comparable results, despite greatly different costs. Under drought‐stress conditions, a significant positive correlation between grain yield and CTD was found on most measurement dates in 2011 and on some dates in 2012. When the CTD was pooled across water regimes, a significant positive correlation between grain yield and CTD was obtained on every measurement date. However, as genotypic differences for CTD were non‐existent, the correlations are less meaningful. The missing genotypic differences for CTD were rather caused by the limited genetic variability of the genotypes used in this study, than by climatic conditions. Due to this limitation, we were not able to make a concluding statement about the CTD in a temperature climate, although the results are quite promising and indicate that the CTD can potentially be used in a temperate climate.  相似文献   

12.
Water stress after flowering, one of the major factors limiting yields of pearl millet, affects both seed setting and grain filling and is a consequence of more/less water used prior to anthesis. However, whether genotypes have different sensitivities for seed setting and filling under drought, if exposed to similar stress intensity, is unclear. Experiments were conducted in two pairs of pearl millet genotypes, that is, PRLT2/89‐33 and H77/833‐2, 863B and 841B, contrasting for terminal drought tolerance, and two genotypes, ICMR 01046 and ICMR 01029 (IL‐QTLs), introgressed with a terminal drought tolerance QTL from PRLT2/89‐33 into H77/833‐2. Total seed weight, panicle number, 100‐seed weight, seed number and stover biomass were measured at different soil moistures and throughout grain filling. Sensitive H77/833‐2 had higher seed number and yield under well‐watered (WW) conditions than in PRLT2/89‐33 and IL‐QTLs. Upon increases in water stress intensity, H77/833‐2 suffered losses mostly in stover biomass (45 %) and seed number (60 %) at 0.3 FTSW whereas the biomass and seed number of PRLT2/89‐33 decreased little (20 % and 25 %). The 100‐seed weight of H77/833‐2 decreased only 20 % under stress. Tolerant 863B also maintained a higher seed number and biomass under water stress than 841B. Grain filling duration in PRLT2/89‐33 and IL‐QTLs was similar to that of H77/833‐2 under WW conditions but lasted longer than in H77833‐2 under water stress (WS). Similarly, seed growth of 863B was longer than 841B under WS. It is concluded that the higher seed yield of tolerant parents PRLT2/89‐33 and 863B, and of IL‐QTLs under WS was explained by the retention of a higher number of seeds than in sensitive lines, while the decrease in the 100‐seed weight was proportionally less than the decrease in seed number. Phenotype with lesser number and larger size of panicles and larger grain size, like genotypes PRLT2/89‐33 and 863B, withstood post‐anthesis water stress better. IL‐QTL inherited part of these characteristics, indicating a role for the terminal drought QTL in maintaining larger seed number and higher 100‐seed weight. The continuous stover biomass increase under WW in H77/833‐2, due to tillering, might indicate that tiller growth and grains are in competition for resources after anthesis, and this may relate to the relatively shorter grain‐filling period.  相似文献   

13.
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   

14.
Finger millet [Eleusine coracana (L.) Gaertn.] is an important coarse cereal crop grown in the arid and semi‐arid regions and often experiences high temperature (HT) stress. The objectives of this research were (i) to quantify effects of season‐long HT stress on physiological and yield traits, (ii) to identify the developmental stages most sensitive to HT stress and (iii) to quantify the genetic variability for HT stress tolerance in finger millet. Research was conducted in controlled environment conditions. HT stress decreased the chlorophyll index, photosystem II activity, grain yield and harvest index. Maximum decrease in number of seeds per panicle and grain yield per plant was observed when stress was imposed during booting, panicle emergence or flowering stages. Maximum genotypic variation was explained by panicle width and number of seeds per panicle at optimum temperature (OT) and grain yield per plant at HT and number of seeds at HT. Based on the stress response and grain yield, tolerant or susceptible genotypes were identified. Finger millet is sensitive to HT stress during reproductive stages, and there was genotypic variability among the finger millet genotypes for number of seeds per panicle and grain yield under HT, which can be exploited to enhance stress tolerance.  相似文献   

15.
Genotypic variability in relation to growth and photosynthetic CO2 assimilation rate (Pn) is well known for maize (Zea mays L.) under heat stress conditions. This study was, however, initiated to test whether genotypic growth variation is related to variations in individual leaf size, leaf extension rate (LER), and photosynthesis of the single leaf at high temperature. Six tropical maize genotypes selected from the International Maize and Wheat Improvement Centre (CIMMYT) with contrasting growth responses were grown for 9 days after emergence (DAE) in the first and for 15 DAE in the second experiment at 25/22 °C and 42/30 °C. High temperature caused a marked decrease in the growth parameters, and the genotypes showed high growth variations irrespective of temperature levels. Interestingly, genotypes did not follow a similar ranking in relation to biomass production between 9 DAE (heterotrophic growth phase) and 15 DAE (autotrophic growth phase) at 25/22 °C, but the pattern was similar at 42/30 °C. Total leaf area and daytime LER of leaves 2 (l2), 3 (l3), and 4 (l4) showed a tight correlation with biomass production at both temperatures, while the LER of the youngest leaf (l4) at night also showed the same correlation at 42/30 °C. A significant relationship between the areas l2 and l3 and biomass was observed only at high temperature and not at 25/22 °C. The Pn decreased markedly at high temperature and genotypic variability was pronounced. The genotypes maintained a similar ranking of Pn measured from l2 at 8 DAE and from l3 at 13 DAE under unfavourable conditions only and not at 25 °C. Of the six genotypes, F250 outperformed the others in relation to growth and Pn activity. A tight correlation between photosynthesis of different leaves and growth was detected at high temperature but not at the optimal temperature for growth. It is concluded that the areas l2 or l3, daytime LER and Pn, all measured at high temperature stress conditions, can be regarded as good indicators of the thermo‐tolerance of tropical maize genotypes at the seedling stage.  相似文献   

16.
The possibility of selecting spring rape for cold tolerance at the mature pollen grain stage was studied by investigating the effects of pollen storage at low temperatures on the quality of pollen grains and on the cold tolerance of the plants generated from them. Pollen treatments of F1 hybrids affected fertilization ability much more than viability and even after 10 days storage at 3 or 10°C the pollen germination percentage was reasonably high. Pollen storage for 7 or 10 days at 3 or 10°C significantly increased the cold tolerance of F2 seed germination, with 3°C being more effective. Pollen storage for a shorter time had no effect upon the number of resulting genotypes tolerant to low temperature. This approach may be successfully applied in plant breeding to enrich segregating plant populations with cold-tolerant genotypes.  相似文献   

17.
The relationship between biomass production and N2 fixation under drought‐stress conditions in peanut genotypes with different levels of drought resistance is not well understood. The objective of this study was to determine the effect of drought on biomass production and N2 fixation by evaluating the relative values of these two traits under well watered and water‐stress conditions. Twelve peanut genotypes were tested under field conditions in the dry seasons of 2003/2004 and 2004/2005 in north‐east Thailand. A split‐plot design with four replications was used. Main‐plot treatments were three water regimes [field capacity (FC), 2/3 available soil water (AW) and 1/3 AW], and sub‐plot treatments were 12 peanut lines. Data were recorded on biomass production and N2 fixation under well watered and water‐stress conditions. Genotypic variations in biomass production and N2 fixation were found at all water regimes. Biomass production and N2 fixation decreased with increasing levels of drought stress. Genotypes did not significantly differ in reductions for biomass production, but did differ for reductions in N2 fixation. High biomass production under both mild and severe drought‐stress conditions was due largely to high potential biomass production under well‐watered conditions and, to a lesser extent, the ability to maintain high biomass production under drought‐stress conditions. High N2 fixation under drought stress also was due largely to high N2 fixation under well‐watered conditions with significant but lower contributions from the ability to maintain high nitrogen fixation under drought stress. N2 fixation at FC was not correlated with the reduction in N2 fixation at 2/3 AW and 1/3 AW. Positive relationships between N2 fixed and biomass production of the tested peanut genotypes were found at both levels of drought stress, and the relationship was stronger the more severe the drought stress. These results suggested that the ability to maintain high N2 fixation under drought stress could aid peanut genotypes in maintaining high yield under water‐limited conditions.  相似文献   

18.
Chickpea is sensitive to low temperature (<10°C) during its reproductive stage. Low temperature adversely affects the development of pods and seeds. This study was undertaken to investigate the role of sucrose metabolizing enzymes in seed development and potential of antioxidative enzymes in protecting seeds and podwalls from the deleterious effects of cold stress in advanced cold tolerant chickpea breeding lines. Healthy pod set was observed in these tolerant lines in the end of December where as low temperature susceptible PBG-1 did not flower. Two lines ICCV 96029 and ICCV 96030 showed susceptible characters such as reduced flowering, blackened and shrivelled seeds and yellowish pods in comparison to other cold stress tolerant lines due to sudden dip of temperature (<1 °C) during the first week of January. These two lines were, therefore, treated as susceptible checks in comparison to other tolerant lines. A significantly higher activity and specific activity of sucrose synthase was observed in seeds of most of the cold tolerant lines in comparison with ICCV 96029 and ICCV 96030, thereby providing sugars as well as sugar nucleotides for their growth and starch synthesis during unfavourable low temperature. The developing seeds and podwalls of tolerant genotypes had higher activities of antioxidant enzymes, i.e. catalase, ascorbate peroxidase and glutahione reductase in comparison with ICCV 96029 and ICCV 96030. It appears that the higher activities of antioxidant enzymes in podwall protect the developing seeds from cold stress.  相似文献   

19.
Among plant species rice (Oryza sativa L.) leaves can be characterised with a very high level of salicylic acid content; however, its exact role is still poorly understood. In the present work, rice genotypes with different levels of drought tolerance have been subjected to PEG‐induced drought or cold stress at 10 °C in order to find relationship between the salicylic acid metabolism and the level of stress tolerance; and between the salicylic acid level and other protective mechanisms. Although the drought‐sensitive genotypes usually contained slightly higher amount of salicylic acid than the tolerant ones, there was no strong correlation between the salicylic acid contents and the degree of drought tolerance. Because the expression pattern of the chorismate synthase and isochorismate synthase genes did not correlate with the level of salicylic acid, but there was a correlation between the levels of salicylic acid and ortho‐hydroxy‐cinnamic, it is assumed that the salicylic acid synthesis via ortho‐hydroxy‐cinnamic acid may play a more decisive role than the chorismate–isochorismate–salicylic acid pathway in rice. While the activity of the glutathione reductase enzyme did not show correlation with drought tolerance, the glutathione S‐transferase activities were usually higher in the leaves of the drought‐tolerant varieties than in the sensitive ones. The salicylic acid contents in the leaves were not substantially affected by the applied stress conditions; however, other stress‐related compounds polyamines showed marked, stress‐specific responses. Correlation data suggest that there is no direct link between the abiotic stress‐induced polyamine changes and the salicylic acid metabolism in rice.  相似文献   

20.
河北省地方水（陆）稻品种耐逆性研究   总被引：6，自引：0，他引：6  
对河北省地方水（陆）稻品种耐逆性进行了鉴定,并在此基础上分析了耐寒性、耐旱性、耐盐性种质分布情况。对耐性频度较高的耐寒性、耐旱性从水、陆稻,熟期,不同稻作区等方面进行了详细研究。结果表明：耐寒、耐旱品种频度高、强度大,耐寒品种高达86.44%,高耐率23.53%;耐旱品种为48.77%,高耐率31.65%;耐盐性品种仅为6.46%,并且无高耐性和耐性品种。耐寒品种频度水稻高于陆稻,各熟期类型分布频度接近,随纬度增加、经度西移和温热条件降低而增加;耐旱性品种频度和强度均是陆稻高于水稻,早稻早熟耐性频度最高,其余熟期比较接近,河北省东北地区高,西北及冀中库淀地区低。  相似文献   

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