共查询到20条相似文献，搜索用时 15 毫秒
1.
《Plant Production Science》2013,16(4):468-472
AbstractImprovement of early seedling growth, such as seedling emergence and vigor is one of the most important agronomic traits in direct seeding rice cultivation. The effects of two plant growth regulators (PGRs), gibberellic acid (GA3) and ethephon (ET), on seedling growth under flooded soil conditions at different temperatures and water depths were investigated. The PGRs were applied during the seed soaking process. A single treatment with GA3 or ET increased seedling growth. However, combined application of GA3 and ET was more effective than that of GA3 or ET alone in many cases at both growing temperatures (15 and 20ºC). The growth of different organs in the rice seedlings, such as the coleoptiles, first leaves, and second leaves was also increased by PGR treatment. The nitrogen concentration of the shoot and the ratio of shoot dry weight to shoot length did not differ significantly among the treatments. The results of our study show that rice seedling growth in direct seeding cultivation may be improved by treatment with GA3 and ET in combination. 相似文献
2.
《Plant Production Science》2013,16(1):45-52
Reactive oxygen species (ROS) play an important role in seed germination. Although hydrogen peroxide (H2O2), a type of ROS, enhances the germination rate of various plant seeds, little is known about the mechanism. NADPH oxidases catalyze the production of superoxide anion (O2-) that is one of the ROS and the enzymes regulate plant development. We, therefore, investigated the role of NADPH oxidases in seed germination and seedling growth in barley (Hordeum vulgare L.). The production of O2- was observed both in embryo and aleurone layers in barley seeds treated with distilled water (DW). However, it was suppressed in seeds treated with diphenylene iodonium (DPI) chloride, NADPH oxidase inhibitor. Moreover, DPI markedly delayed germination and remarkably suppressed α-amylase activity in barley seeds, indicating the importance of NADPH oxidases in germination of barley seeds. The gene expression and the enzyme activity of NADPH oxidases gradually increased after imbibition, and the enzyme activities were closely correlated with seedling growth after imbibition. Besides, DPI markedly suppressed the seedling growth. These results indicated that NADPH oxidases perform a crucial function in germination and seedling growth in barley. These facts clearly reveal that O2- produced by NADPH oxidases after imbibition regulates seed germination and seedling growth in barley. 相似文献
3.
《Plant Production Science》2013,16(4):455-463
AbstractAbstract: We investigated the effects of soaking temperature and duration on the germinability of seeds of rice (Oryza sativa L., cv. Koganemochi, Gohyakumangoku, and Koshihikari) that had been stored for a long period. The germinability of the seeds soaked at 5ºC for 5 d was markedly lower than that of seeds soaked at 12ºC for 5 d. The germinability of the seeds soaked at 5ºC for 24 hr was not increased by subsequent soaking at 12ºC for 4 d. On the other hand, the germinability of the seeds soaked either at 12ºC for 24 hr or at 30ºC for 80 min was similar to that of seeds soaked at 12ºC for 5 d, even when followed by treatment at 5ºC. Thus, the soaking temperature during the first 24 hr was most important for the germination of rice seeds that had been stored for a long period. Western blotting analysis revealed characteristic expression patterns of α-amylase isoforms in cultivars correlating with the germinability after soaking at a low-temperature. 相似文献
4.
《Plant Production Science》2013,16(3):166-172
AbstractTo elucidate the physiological characteristics relating to better seedling establishment in submerged field under low-temperature conditions, we compared the time required to reach various growth stages after seed imbibition among rice {Oryza sativa L.) varieties differing in the performance of seedling establishment. Two experiments were conducted. In the field experiment, the percentage of seedlings with expanded second leaf at 30 days after sowing (PSSL) was measured and regarded as the index of establishment rate for each variety. In agar-bed experiment, the number of germinated seeds, the seedlings with the coleoptile elongated to the medium surface, and the seedlings with the 1st leaf apparent were counted daily under a 16°G condition. A sigmoid model was applied to the above values to evaluate the time requirements. There was a significant correlation between the duration from 50% germination to 50% emergence in the agar-bed experiment and PSSL in the field experiments. However, the duration from imbibition to 50% germination, and that from 50% emergence to 50% appearance of the first leaf were not significantly correlated with PSSL. We found that fast growth of the coleoptile is an important characteristic for the varieties that can provide stable and excellent seedling establishment at low temperature. 相似文献
5.
《Plant Production Science》2013,16(1):108-115
Conventional seedling mats for rice transplanters in Japan are heavy to carry, and much labor is required to collect, wash and store the nursery boxes. In addition, seeding time overlaps with the labor peak in spring. To reduce such labor, we developed a “seed-mat” consisting of hardened rice seeds (Oryza sativa L.) glued onto a molded rice-hull mat with a cover of soil glued on. Seed hardening, which is done by soaking seeds in water at 15ºC for 5 d followed by drying, and heating of the seeds at 50ºC for 5 or 7 d, reduced the time to 50% germination (T50). In dormant seeds, the heating before the hardening enhanced the effect of the hardening more than the heating after the hardening. Seed hardening increased the dry weight of the shoots from the seed-mats. Covering the mat with soil also increased the percentage of seedling emergence, shoot length, number of leaves and shoot dry weight of the seed-mats. The hardened seeds maintained short T50 and 95% or higher germination for 120 d at room temperature. In the seed-mat, the hardened seeds maintained 95% or higher seedling emergence for 208 d. In conclusion, superior seed-mats could be produced using the procedure involving both seed hardening and cover of soil. The seed-mats can be prepared in winter and stored until seedling-raising period in spring. By the seed-mats, seedling mats can be prepared for the rice transplanter without using nursery boxes, which take up storage space and require much labor. 相似文献
6.
《Plant Production Science》2013,16(3):210-214
SummaryThe cell elongation-promoting activities of brassinolide (BR) and indoleacetic acid (IAA) in the lamina-inclination test using etiolated rice seedlings were compared at a low temperature. IAA promoted the lamina joint-cell elongation at 30°G, but the effect was markedly lowered with decreasing temperature and reached null at 15°C. On the other hand, BR and castasterone (CAS), a brassinosteroid, promoted this cell elongation even at 15°G. Homobrassinolide (HBR), a brassinosteroid, also promoted this cell elongation, although the activity was weak. The combination of BR and IAA synergistically promoted this cell elongation at a low temperature (15°G).Immersion of the dry seeds in 2 X 10-8 M BR for the first 24 h promoted the early growth of rice seedlings. This treatment also enhanced the germination rate and the growth after direct sowing in submerged paddy pots in a greenhouse or phytotron at a low temperature (15°C). Leaf spraying of BR on the rice seedlings at the 4th leaf stage increased plant height and the fresh weights of tops and roots even at a low temperature. BR sprayed on the completely expanded 4th leaves did not increase their blade length, but that sprayed on the expanding 5th and 6th leaves strikingly increased their blade length, and the effect tended to be stronger at a low temperature.These results suggest that BR promotes cell elongation in young rice seedlings under low-temperature stress, although IAA had no such effect, and that BR may promote germination and the early growth of rice seedlings at a low temperature in direct sowing in the submerged paddy field and in the rice nursery. 相似文献
7.
《Field Crops Research》2006,98(1):68-75
Direct seeding instead of transplanting for rice (Oryza sativa L.) has increasingly been used in northern and eastern China because of labor and cost saving. However, poor germinability is still one of the major problems faced in the adoption of direct seeding under low temperature (low temperature germinability: LTG) and anoxia (anoxia germinability: AG) condition. To gain an understanding of the genetic control of seed germinability under these unfavourable conditions, two rice lines, USSR5 (japonica type) and N22 (indica type) and F2 individuals derived from the cross USSR5 × N22 were tested for LTG and AG. USSR5 and N22 differ significantly for both LTG and AG. The LTG of the F2 individuals ranged from 0 to 100% after a 10 days incubation. AG ranged from 0.0 to 4.0 cm shoot length. Based on segregation in the F2 population, a linkage map was constructed using 121 SSR markers. The map covered 1821.5 cM, with a mean inter-marker distance of 16.7 cM. Eleven putative QTLs for LTG were detected, one on each of chromosomes 3–5, 7, 9–11, and four on chromosome 5. The USSR5 alleles in all these QTLs acted to increase LTG. Two QTLs for AG were located on chromosomes 5 and 11, respectively, at both of which the USSR5 alleles acted to increase AG. We propose that USSR5 could make a major contribution to improving LTG and AG in rice breeding programs. 相似文献
8.
播种方式和播种密度对杂交籼稻机插秧节本增效的研究 总被引：3，自引：1，他引：2
【目的】探索机插杂交籼稻稀播育秧秧苗生长特性、栽插质量、产量与效益特点。【方法】以F优498和Ⅱ优498的种子为材料开发并优选条播器后,采用两因素裂区设计,播种方式为主区,播种量为副区。【结果】条播播种均匀度优势明显,24行条播规格效果最佳。播种14 d后,秧苗开始产生分蘖芽,播后17至23 d是分蘖芽发生速率最快时期。随播种密度的增加,成苗率、干物质积累量、根冠比、秧苗充实度、N积累量、分蘖芽发生率、发根力、漏插率都呈降低趋势,同时有效穗数增加,每穗粒数减少,产量先增加后降低。条播相对于散播,秧苗整体素质较好,易形成壮秧,产量较高。【结论】投入与产出综合分析,采用条播方式,播种密度为50 g/盘时,秧苗群体密度和个体优势之间能得到较好的协调,产投比最高。 相似文献
9.
In seed priming, seeds are soaked in a solution of low water potential and dried back to their original weight. This study was conducted to evaluate the comparative performance of different seed priming treatments and to investigate whether re-drying is essential or not? Seeds of fine grain aromatic rice (Oryza sativa L.) cultivar Super-Basmati were subjected to hardening, osmohardening with CaCl2 and KCl (ψ s ?1.25 MPa) each for 24 h (one cycle), and hydropriming and ascorbate priming (10 mg L?1) for 48 h. Seeds were primed in two sets. In one set after each treatment, seeds were given three surface washings with distilled water and dried back near to original moisture contents with forced air. In the other case, after surface washings with distilled water, seeds were surface dried using blotting paper and sown immediately. All the priming treatments improved the emergence, seedling growth and reserve metabolism. Use of surface drying was more effective for rice seed invigoration, as evident from earlier and synchronized seedling emergence. Moreover, shoot and root length, seedling dry weight, root score, α-amylase activity, soluble sugars and dehydrogenase activity were also improved, although germination percentage and leaf score were similar from both strategies. Results suggested that surface drying, rather than re-drying close to original weight, was more effective, while among the treatments, osmohardening with CaCl2 was the most effective. Increasing rice production with judicious use of water is need of the day, and aerobic rice cultivation is an attractive alternative for this purpose. However, poor and erratic stand establishment is one of the major hindrances in its wide scale adoption. In this regard, seed priming techniques are pragmatic approaches to achieve proper stand establishment in the new rice culture. They help in improving seedling density per unit area under optimal and adverse soil conditions and may be opted to improve the performance of aerobic rice. 相似文献
10.
Chinese yam (‘yam’) was grown at different carbon dioxide concentrations ([CO2]), namely, ambient and elevated (ambient + 200 μmol mol?1), under low- and high-temperature regimes in summer and autumn, separately. For comparison, rice was also grown under these conditions. Mean air temperatures in the low- and high-temperatures were respectively 24.1 and 29.1 °C in summer experiment and 20.2 and 24.9 °C in autumn experiment. In summer experiment, yam vine length, leaf area, leaf dry weight (DW), and total DW were significantly higher under elevated [CO2] than ambient [CO2] in both temperature regimes. Additionally, number of leaves, vine DW, and root DW were significantly higher under elevated [CO2] than under ambient [CO2] in the low-temperature regime. In autumn experiment, tuber DW was significantly higher under elevated [CO2] than under ambient [CO2] in the high-temperature regime. These results demonstrate that yam shows positive growth responses to elevated [CO2]. Analysis of variance revealed that significant effect of [CO2] × air temperature interaction on yam total DW was not detected. Elevated-to-ambient [CO2] ratios of all growth parameters in summer experiment were higher in yam than in rice. The results suggest that the contribution of elevated [CO2] is higher in yam than in rice under summer. Yam net photosynthetic rate was significantly higher under elevated [CO2] than under ambient [CO2] in both temperature regimes in summer. Elevated [CO2] significantly affected on the rate in yam but not in rice in both experiments. These findings indicate that photosynthesis responds more readily to elevated [CO2] in yam than in rice. 相似文献
11.
ABSTRACTEarly seedling growth, including seedling emergence and vigor, is crucial in direct seeded rice. In this study, we examined the effects of gibberellic acid (GA3) and ethephon (ET) on the early growth of direct seeded rice, and on α-amylase activity and soluble sugar content in the seeds. Rice seeds were treated with water (control), ET, GA3, or ET+ GA3 and were allowed to grow for 21 days. The results showed that ET and GA3 synergistically improved the lengths of mesocotyl, coleoptile, mesocotyl+ coleoptile, and first leaf. Moderate synergistic effects of ET and GA3 were detected in the second and third leaves. ET+ GA3 treatment induced higher α-amylase activities during early post-germination growth, which is consistent with the longer coleoptile, mesocotyl, mesocotyl+ coleoptile, and first leaf. In addition, ET+ GA3 induced higher α-amylase activity in the seeds, and consequently, higher sucrose and glucose concentrations than other treatments. These results partially explain the regulatory mechanism underlying the synergistic interaction of ET and GA3 on rice seedling growth in terms of starch and sugar metabolism in the seeds, and this knowledge is expected to facilitate the practical use of ET and GA3 in direct seeded rice systems. 相似文献
12.
The efficiency of microwave treatment in breaking the hard seed coat dormancy in Stylosanthes seabrana was compared with three other conventional methods including mechanical scarification, hot water treatment (100°C for 1 min) and acid scarification (5 min). The microwave treatment was as efficient in breaking hard seed coat dormancy as the hot water treatment. The ranking of treatments followed the order microwave ≥ hot water ≥ acid > mechanical scarification > control. The electrical conductivity of microwave‐treated seeds, although less than that of hot water, was greater than untreated control seeds, indicating increased permeability of the seed coat for water uptake. Seedling vigour, based on seedling length, was also similar for these treatments. Respiration was found to be higher in microwave‐treated seeds. Although levels of food reserves were not measured, future studies could hypothesize that increased imbibition of water in microwave‐treated seeds could cause a faster breakdown of food‐reserve material that is supplied to the germinating seed, resulting in increased evolution of CO2 through respiration. Scanning electron micrographs indicated the appearance of cracks and blisters on the seed surface of microwave‐treated seeds. These are most likely the sites of water entry during imbibition. 相似文献
13.
The present study investigated the effects of elevated carbon dioxide concentration ([CO2]) and air temperature on the germination of seed bulbils and the seedling vigour of two Chinese yam lines. Plants were grown under two [CO2] levels, ambient and elevated (ambient + 200 μmol mol?1), and two mean air temperature regimes, 22.2 °C (ambient + 1.4 °C) and 25.6 °C (ambient + 5.2 °C). Elevated [CO2] did not affect bulbil germination under both air temperature regimes. During the early growth stage, the dry weight (DW) of leaves, vines, shoots, roots, belowground parts (roots + tubers) and whole plants were higher under elevated [CO2] than ambient [CO2] for both lines under the low- and high-temperature regimes. The values of vigour indexes (index I = germination % × seedling length and index II = germination % × seedling DW) were also higher under elevated [CO2] than ambient [CO2] for both lines. These results indicated that Chinese yam seedlings respond positively to elevated [CO2] during the early growth stage. The above:belowground DW ratios were lower under elevated [CO2] than ambient [CO2] in seedlings with very small new tubers for both yam lines, indicating that elevated [CO2] strongly affected the root growth in the early growth stage. The DWs of post-treatment seed bulbils were higher in the elevated [CO2] under both air temperature regimes. The results showed that Chinese yam used a smaller amount of the reserves in seed bulbils under elevated [CO2] than under ambient [CO2]. 相似文献
14.
以玉米品种农大108为试验材料,当玉米幼苗2叶1心时,一部分在常温下(25℃/18℃)培养,另一部分在低温下(10℃/4℃)培养,以叶片喷施0.4 mmol/L亚精胺为处理组,喷施蒸馏水为对照组,研究亚精胺在玉米幼苗冷胁迫过程中的作用。结果表明,低温胁迫抑制了幼苗生长,加剧了叶片中超氧自由基和过氧化氢的产生,提高了膜脂过氧化水平,降低了叶绿素含量。叶片喷施亚精胺,显著缓解了冷胁迫导致的生长抑制、叶绿素含量下降、活性氧积累和膜脂过氧化,提高了幼苗可溶性糖和脯氨酸含量,使抗氧化酶活性显著提高。此外,亚精胺处理提高了冷胁迫条件下幼苗热激蛋白HSP70和HSP90的mRNA和蛋白表达水平。结果表明,外源亚精胺能提高玉米幼苗的抗寒性。 相似文献
15.
《Field Crops Research》2004,85(1):21-30
Grain sorghum (Sorghum bicolor (L.) Moench) originated in the semi-arid tropics and is generally sensitive to low-temperature stress. Early planting and use of minimum tillage necessitate the development of sorghum hybrids with early season cold tolerance. Genetic variability for cold tolerance exists in sorghum and has been detected by early planting under field conditions and by analysis of seeds and plants under growth chamber conditions. There is limited information on the efficiency of evaluating cold tolerance under growth chamber conditions and the relationship with field performance. The objectives of this study were to quantify the variability of cold tolerance in commercial hybrid seed lots under growth chamber conditions, to exam different components of cold tolerance and their relationships, and to evaluate the consistency of lab test results with data from field tests. Thirty commercial hybrid seed lots were evaluated by growing the entries under 15/10, 13/10, 11/8, and 25/20 °C day/night temperature in a 13/11 h cycle in a growth chamber. Traits measured included emergence percentage, emergence index, shoot and root dry weight, seedling height, and vigor score. Significant genotypic differences were detected for all traits. Correlations among the traits were significant and favorable, which confirmed that simultaneous improvement of these traits should be possible. The same seed lots were also evaluated in a soil-free plate-based assay, in which percent germination, and shoot and root elongation of the seed lots grown in dark at 15 °C were measured. Results from both laboratory tests, soil-based and plate-based, were correlated with data collected in a field study, which was conducted to evaluate cold tolerance of commercial sorghum hybrids at Manhattan, Hesston, Bellville, and Garden City, KS in 1998 and 1999. Single-trait correlations between lab and field studies were significant. Differentiation based on rank-summation index of common traits, rank-summation index correlations and the overlap of best entries, further provided strong support of the efficiency of predicting and identifying elite hybrids using growth chamber assays. 相似文献
16.
Relationship Between Allelopathic Effects and Functional Traits of Different Allelopathic Potential Rice Accessions at Different Growth Stages 总被引：1，自引：1，他引：0
Xu Gaofeng Shen Shicai Zhang Fudou Zhang Yun Kato-Noguchi Hisashi Roy Clements David 《水稻科学》2018,25(1):32-41
In this study,effects of temperature,light and their interactions on allelopathic effects and the functional traits specific leaf area(SLA)and stem mass fraction(SMF)of different allelopathic potential rice accessions at different growth stages were analyzed.The main results were as follows:Allelopathic responses to temperature and light varied with different allelopathic potential rice accessions at different growth stages.With the rise of temperature and the extension of photoperiod,allelopathic effect increased firstly and then decreased at 2–3 leaf stage,but increased constantly at the 4–5 and 7–8 leaf stages in strong allelopathic rice accessions[O.longistaminata,F1(O.longistaminata×RD23),F2(RL159 and RL169)].Temperature had significant impact on allelopathic effect without considering light factors,but light showed little effect on rice allelopathy at the same temperature conditions.The greatest allelopathic effect was attained with moderate temperature and long photoperiod at 2–3 leaf stage in strong allelopathic rice accessions,but all the rice accessions showed weak allelopathic effects at the low temperature condition(15oC/10oC),and the influence of different factors on allelopathy followed a general trend as temperatureleaf stagelight,indicating that among the multiple factors impacting rice allelopathy,temperature was the main factor.Allelopathic characteristics of F1 and F2 to various temperature and light were similar to O.longistaminata,showing that allelopathic genes from wild rice can be expressed in its descendants.Temperature and light also had significant effects on SLA and SMF,and rice allelopathy was closely correlative to SLA in strong allelopathic rice accessions at the 4–5 and 7–8 leaf stages,but there was no correlation between rice allelopathy and SMF at different growth stages.These results suggested that rice adjust the relationship between allelopathy and SLA and adapt to the varied environments,and that high temperature and long photoperiod can enhance rice allelopathic activity. 相似文献
17.
为明确外源硝态氮对高铵胁迫下小麦幼苗生长的影响及其生化机理,采用温室水培的方式,以豫麦49(耐高铵品种)和鲁麦15(高铵敏感型品种)为材料,研究了外源硝态氮对高铵胁迫下小麦幼苗形态、激素含量和抗氧化系统的影响。结果表明,高铵胁迫条件下,外源硝态氮显著增加两个小麦品种株高、根长、干重,其中鲁麦15的地上部干重增加量高于豫麦49,而根系干重增加量则表现为豫麦49高于鲁麦15。高铵胁迫下,两个小麦品种植株的IAA、CTK含量、IAA/CTK显著低于对照;外源硝态氮处理5 d后,豫麦49地上部和根系IAA含量、根系CTK含量显著增加,恢复至对照水平;鲁麦15植株虽亦表现显著增加,但仍低于对照。另外,外源硝态氮对高铵胁迫下两个小麦品种地上部和根系的O■释放速率、SOD和POD活性及MDA含量没有显著影响。综上,外源硝态氮缓解小麦幼苗生长高铵胁迫的原因可能是通过增加IAA和CTK合成和转运,影响IAA和CTK之间的平衡,进而达到缓解效果。品种间比较,耐铵型品种豫麦49缓解作用可能源于对地上部和根系IAA含量以及根系CTK含量的协同调控;而高铵敏感型品种鲁麦15的缓解作用可能主要源于对地上部IAA含量的调控。 相似文献
18.
《Plant Production Science》2013,16(2):178-183
AbstractThe effects of day length and air temperature on the growth and flowering of sesame (Sesamum indicum L.) were examined to analyze the effect of seeding date on the seed yield. Short day (10-h light/14-h darkness) treatment decreased the final stem-length relative to natural day length (14.1～13.4-h), although it hardly affected the length of the stem-elongation period. The short-day treatment shortened the duration to the first flower and lowered the first flowering-node. It prolonged the flowering period, but decreased the flowering-node number on the main stem resulting from the slower rate of increase in nodes with flowers. Under a low day/night temperature condition (23/18ºC), the stem growth was very slow and flowering did not occur. As compared with a high temperature (30/23ºC), a low temperature (22/15ºC) during 15 days after emergence suppressed the seedling growth temporarily, but the seedlings resumed growth after the temperature treatment. The growth and flowering behavior after the treatment were unaffected by a low temperature during the seedling stage. On the other hand, a low temperature during the flowering period decreased the flowering-node number resulting from the slower rate of increase in nodes with flowers, although it prolonged the flowering period. In this study, the decrease in the flowering-node number by short days and low temperature was smaller than that by delay of seeding date as observed in our previous study. Thus, the effects of day length and air temperature were not the sole factors responsible for the effect of seeding date on the flowering-node number. 相似文献
19.
Summary The influence of three environmental factors on the incidence of arrested floral development (bud abortion) in different potato
clones was studied. The first experiment measured flower production in growth chambers when a 12-h photoperiod was extended
by 4 h dim light. The second experiment, also in growth chambers, contrasted flower production under night temperatures of
10°C and 20°C (day temperature 30°C, photoperiod 12 h). A third experiment examined bud abortion in plants grown in the greenhouse
under shade cloths which reduced incoming irradiance to ca. 50% of normal. Both the longer photoperiod and warmer night temperature
promoted flower production, in some of the clones tested, by reducing bud abortion. Reduced irradiance completely suppressed
flower development (but not bud formation) in all clones. In all experiments, the number of flowers developing to anthesis
was significantly correlated with shoot dry weight, indicating that treatments which promote shoot growth reduce the incidence
of bud abortion.
Paper No. 854, Department of Vegetable Crops, Cornell University. 相似文献
20.
Humberto Antonio López-Delgado Ricardo Martínez-Gutiérrez Martha Elena Mora-Herrera Yamile Torres-Valdés 《Potato Research》2018,61(3):195-206
Low temperature stress is a current challenge to plants that is associated with climate change. In plants, exposure to extreme temperatures is followed by the accumulation of reactive oxygen species, such as hydrogen peroxide (H2O2), leading to oxidative stress. Salicylic acid (SA) and H2O2 mediate the tolerance responses to stress and have been reported to induce freezing tolerance in potato microplants. The objectives of the present investigation were (1) to evaluate the short- and long-term effects of H2O2 and SA treatments on freezing tolerance in potato (Solanum tuberosum L.) plants grown from tubers and (2) to analyse the relationship between catalase (CAT) activity and H2O2 concentration associated with freezing tolerance responses. We observed the lowest freezing survival rates in 45-day-old potato plants (cv. Granate) compared to younger plants. The two treatments consisted of (1) the tuber-dip (long-term) treatment in which sprouted minitubers were saturated for 1 h in SA 10?5 M or H2O2 1 mM and planted in soil under greenhouse conditions and (2) the crop-spray (short-term) treatment in which plants 5–8 cm high were sprayed twice a week with SA 10?5 M or H2O2 1 mM until 45 days of age. In all treatments, 45-day-old plants were then exposed to ? 6?±?1 °C for 4 h. The survival rate was measured 15 days after freezing. CAT and H2O2 measurements were performed 1 h before and after the freezing treatment. The results showed that SA and H2O2 induced freezing tolerance in both the short- and long-term treatments. Survival was significantly higher in SA- and H2O2-treated plants than in control plants. In both the long- and short-term treatments this higher survival was associated with lower internal H2O2 concentrations after freezing compared with control plants and decreasing oxidative stress. SA and H2O2 induced different levels of CAT activity after freezing compared to that found in the control plants in the long- and the short-term treatments. These results suggest the SA and H2O2 function in independent pathways in terms of their induction of freezing tolerance that depends on the method the treatment was applied, by spraying the canopy or by immersion of the sprouted seed tuber. 相似文献