Evidence for Repair Processes in Onion Seeds during Storage at High Seed Moisture Contents

Survival curves of four seed lots of onion held at 15%, 20%and 25% seed moisture content (me) and 45 ° C for 24 h showeda fall in seed germination at all moisture contents. The rateof loss of viability was less for seeds held at 20% and 25%me than that of seeds held at 15% me, with low vigour seedsshowing the greatest reduction in the rate of deteriorationat the high moisture contents. This is interpreted as evidencefor the activation of repair processes in seeds during periodsof partial seed hydration and discussed in relation to seedinvigoration treatments. Key words: Seed moisture content; Storage, Repair, Priming, Invigoration     

Temperature Dependence of Viability and Dormancy of Zizania palustris var. interior Seeds Stored at High Moisture Contents

Seeds (caryopses) of North American wild rice (Zizania palustrisvar. interior), a temperate aquatic grass, have been thoughtto require storage at low temperatures and high moisture contentsto preserve viability. The seeds are also deeply dormant atmaturity and require up to 6 months of stratification to breakdormancy. We report here that wild rice seeds can retain viabilityat moisture contents 30% (f. wt. basis) for up to 6 monthsat temperatures as high as 30 °C, and for at least 1 yearat temperatures below 20 °C. Dormancy is not broken at temperaturesabove 10 °C, but subsequent stratification requirementsare unaffected by prior warm storage. Cold storage is thereforenot required to maintain viability of wild rice seeds, but isnecessary to break dormancy. Hydrated wild rice seeds can befrozen to –10 °C without damage, but dormancy is notlost at subfreezing temperatures. These results provide newoptions for long-term storage of wild rice seeds. Zizania palustris var. interior (Fassett) Dore, wild rice, seed, germination, dormancy, storage, moisture content     

Germination of Stored Cassava Seed at Constant and Alternating Temperatures

Cassava seed is only capable of germinating over a restrictedrange of constant temperatures. During storage the optimum constanttemperature for germination decreases from about 35 to 30 °Cor possibly less. The rate at which the optimum temperaturechanges during dry storage increases with increase in storagetemperature over the range 0 to 40 °C. Some alternating-temperatureregimes (16 h at the lower temperature; 8 h at the higher temperature)can provide conditions as favourable for germination as theoptimum constant temperatures. Furthermore, it has been shownthat temperature alternation itself is stimulatory because whenthe range of the alternation does not include the optimum constanttemperature value, percentage germination is often higher thancould be obtained at any constant temperature within the range,though this stimulatory response declines during storage. Forthese reasons it is provisionally recommended that cassava seedshould be germinated at 25/35 °C which is as stimulatorya treatment as any which has so far been investigated and hasthe advantage of encompassing the range over which the optimumconstant temperature changes during storage. Manihot esculenta Crantz, cassava, germination, dormancy, seed viability, storage of seeds, after-ripening     

The Potential for Newly-Germinated Cabbage Seed Survival and Storage at Sub-Zero Temperatures

The moisture content of newly germinated cabbage seed (radicles1 05 mm long) was reduced to 14% of f.wt without loss of viability.As the moisture content was reduced below 45%, the temperatureat which the germinated seeds froze, and therefore died, decreasedprogressively to a minimum of –34 C at 19% moisture content.No freezing exotherms were recorded in seeds with moisture contentsbelow 19%. Seeds with a moisture content between 14 and 16%maintained viability for at least 1 week when cooled at 26C.min^–1to –20 C and held at this temperature, indicating thepotential for prolonged storage of these low-moisture-contentgerminated (LMCG) seeds. Brassica oleracea, cabbage, germinated seed, seed storage, fluid drilling, freezing exotherm, thermal analysis     

Survival and Vigour of Lettuce (Lactuca sativa L.) and Sunflower (Helianthus annuus L.) Seeds Stored at Low and Very-low Moisture Contents

Seeds of lettuce (Lactuca sativa L.) and sunflower (Helianthusannuus L.) were stored hermetically at 35 °C with 11 differentmoisture contents between 1·3 and 6·9%, and between1·3 and 7·1% of fresh mass, respectively. Germinationand vigour (mean germination time, root length, seedling dryweight) were determined after storage for 0, 8, or 16 weeks(sunflower) or 0, 8, 16, or 48 weeks (lettuce) in these environmentsfollowed by various humidification treatments (to avoid imbibitioninjury). The range of seed storage moisture contents over whichdeterioration was minimized depended upon the criterion of deteriorationused, and varied somewhat between species. Comparison of theseranges for seeds stored for the longest durations showed thatfor some criteria seed performance was poorer (P < 0·05)at both the lowest and highest moisture contents investigatedthan at certain of the intermediate storage moisture contents(e.g, most rapid germination occurred in sunflower followingstorage at 2·2-4·7% moisture content), whereasfor other criteria all the drier storage moisture contents weresuperior to the more moist (e,g. greatest seedling growth occurredin sunflower following storage at 1·3-5·1% moisturecontent). But none of these results suggested that lettuce andsunflower seeds stored hermetically at 2·5-3·0%or 2·2-2·5% moisture content, respectively, wereless vigorous than at any other moisture content tested. Inboth species, these storage moisture contents are in equilibriumwith about 8-10% relative humidity (r.h.) at 20 °C, whichis similar to and indeed marginally less than the 10-13% r.h.recommended following earlier studies on the longevity of seedsin hermetic storage at much warmer temperatures. Thus, theseresults show no evidence that the optimum seed moisture contentfor storage increases with decrease in temperature, at leastover the range 35-65 °C, as has been suggested elsewhere.We conclude that the international recommendation for the long-termseed storage for genetic conservation at 5 ± 1% moisturecontent should not be revised upwardly, and that in situationswhere refrigeration cannot be provided storage at even lowermoisture contents is worthy of further investigation for thoseseeds in which desiccation at 20 °C to equilibrium at 10%r.h. results in moisture contents well below 5%.Copyright 1995,1999 Academic Press Helianthus annuus L., sunflower, Lactuca sativa L., lettuce, desiccation, seed storage, seed vigour     

Survival of Vibrio parahaemolyticus in Oyster Shellstock at Two Different Storage Temperatures

In oyster shellstock harvested from Maryland waters Vibrio parahaemolyticus was found to be present, to survive storage for at least 3 weeks at 4 C, and to multiply after being held for 2 to 3 days at 35 C.     

Evaluation of Bacterial Diversity in Soil Microcosms at Different Moisture Contents

The succession analysis of bacterial diversity in the A horizons (rich in organic matter) of three contrasting types of soil—burozem, soddy gley soil, and chernozem—showed that the bacterial diversity of soil microcosms in humid regions can be adequately evaluated only if soil samples are incubated at different soil moisture contents. A complete account of actinobacteria and proteobacteria requires the levels of soil moisture corresponding to the maximum capillary–sorption moisture and capillary moisture, respectively. The bacterial diversity, whose value was maximum on the 40th day of succession, was higher in soddy gley soil than in burozem. The taxonomic structures of the bacterial communities of these two types of soil were different. After wetting chernozem samples from arid regions, the soil bacterial community changed insignificantly with time and drastically differed from that of soils from humid regions. The difference in the bacterial diversity of soils was the most distinct when it was evaluated by measuring the proportion between proteobacteria and actinobacteria.     

不同温度下四川金川县岷江柏种子的发芽特征

岷江柏(Capressus chenggiana S．Y．Hu)是我国川甘地区特有的濒危乔木。通过对不同温度下岷江柏种子的发芽特征研究,分析了种子的发芽周期和最适发芽温度,以及温度对种子发芽的影响,并讨论了岷江柏的发芽特征与环境温度的关系,从而为岷江柏的人工繁育和物种保护提供了理论依据。结果表明：种子发芽周期为20d,其中0～5d为萌动期,5～15d为高峰期。种子发芽温度为5℃～30℃,适宜发芽温度为10℃～25℃,5℃和30℃不利于种子发芽。在贮藏过程中,贮藏开始阶段10℃不利于种子发芽,贮藏4～10个月后10℃～25℃种子发芽的差别不明显。种子最适发芽温度在2003年1月、4月、7月和10月分别为：20℃、15℃、20℃、25℃。在贮藏过程．不同温度下种子的发芽率、发芽势和T50都有显著影响。岷江柏种子的发芽周期和最适发芽温度．以及贮藏过程中的发芽特征与环境温度有着密切的关系．这是植物对自然环境的一种适应。     

不同温度下贮藏的食用百合种球发根和完好率以及嗣后的植株生长

在采用的温度2、7、12和18℃中,随着贮藏温度升高和时间的延长,食用百合种球腐烂程度加重。2℃处理130d对种球质量无明显影响。随着种球贮藏时间延长,鳞茎产量递增。但贮藏时间过长,影响植株生长。兰州百合于2℃下贮藏的鳞茎产量高于7℃下贮藏的,12℃下贮藏的种球种植后不萌发;龙牙百合以7℃下贮藏的产量为最高,2℃下的次之;宜兴百合以2℃下贮藏的产量为最高,12℃下为最低。兰州百合和宜兴百合适合于2℃下贮藏,龙牙百合的最佳贮藏温度为7℃。     

The Basis for Different Sensitivities of Photosynthesis to SO2 in Two Cultivars of Pea

Alscher, R., Bower, J. L. and Zipfel, W. 1987. The basis fordifferent sensitivities of photosynthesis to SO₂ in two cultivarsof pea.—J. exp. Bot. 38: 99–108. The response of several physiological parameters to exposureto SO₂ (0?8 ppm and 0?6 ppm) was studied in two cultivars ofPisum sativum in which photosynthesis showed a different sensitivityto SO₂. Leaf conductance was slightly reduced during exposureto SO₂ in the sensitive but not the insensitive cultivar. Moresulphite accumulated in the leaves of the sensitive than inthose of the insensitive cultivar. Total leaf content of reducedglutathione in the insensitive cultivar increased during exposureto SO₂, while in the sensitive cultivar there was no increaseuntil the post-exposun period. The activities of fructose l,6-bisphosphataseand glyceraldehyde-3-phosphate dehydrogenase did not decreasegreatly in either cultivar, although activities of enzymes fromthe sensitive cultivar were more affected by SO₂ than were thoseof the insensitive cultivar. Exposure to SO₂ also had littleeffect on either coupled or uncoupled electron transport ofisolated thylakoids from the leaves of either cultivar. Increasedglutathione in the insensitive cultivar may protect the photosyntheticapparatus against SO₂ Key words: SO₂, photosynthesis, light modulation, glutathione     

低温贮藏期间不同含水量郁金香种球的几种生理生化指标变化

郁金香品种'阿波罗'(Apeldoorn)种球含水量分别为66.5%、64.4%和62.8%,贮藏于(2±0.5)℃下16～28周,16周内定期测定各种生理生化指标的结果表明,随着含水量的降低,种球鲜重减少的速率趋小,周径增加的速率趋大;3种种球的呼吸速率均表现为0～8周急剧下降,8～16周回升;贮藏期间种球的淀粉含量逐渐减少,而可溶性糖含量逐渐增多,含水量为62.8%的种球中可溶性糖含量最高.种植试验表明,随着贮藏时间的增加,含水量为62.8%的种球株高、花高、发芽率和开花率都高于其余种球.     

Effect of Gibberellic Acid on Dark and Light Germination at Different Temperatures of Calluna, Ledum andRhododendron Seeds

The aim of the experiments was to study the effects of gibberellic acid (GAs) on the germination of Calluna vulgaris L., Ledum palustre L. and Rhododendron lapponicum (L.) Wahlenb. seeds under different environmental conditions. Under continuous light from white fluorescense tubes (3000 lux), untreated seeds of Calluna were partly dormant at all temperatures studied (9, 15, 21, 27, 27/9, 8/16 hours). Percentage of dormant seeds increased, however, with decreasing temperature, and it varied also from seed lot to seed lot. Untreated seeds of Ledum were dormant in light at 9° and 15°C but not at higher temperatures. Untreated seeds of Rhododendron were completely dormant in light at temperatures from 13° to 24°C. Seeds of all species were completely dormant in darkness both at 15° and 27°C. GA₃ stimulated greatly the germination of all species under all studied environmental conditions. The used concentrations (0.2–3.2 mM) gave nearly 100% germination in most cases. At 9°C the dormancy in some seed lots of Calluna and Ledum was only partly broken by the used concentrations of GA₃.     

Isoenzymes of Lactate Dehydrogenase in Swine Stability During Storage at Different Temperatures and By Heat Treatment

The isoenzymes of lactate dehydrogenase (LDH) in serum from normal pigs were studied after separation by agar gel electrophoresis with subsequent staining with a tetrazolium salt. Experiment 1. The stability of isoenzymes was investigated for 5 successive days after storage at room temperature (22°C), in the refrigerator (4°G), and once after storage for 32 days in the deep-freezer (—20°C). Greatest loss of activity was seen after storage in the refrigerator, where LDH2 and LDH3 lost most of its activity after 5 days. In LDH4 and LDH5 no loss had occurred at this time. Also at room temperature great losses were seen in LDH2 and LDH3. After storage in the deep-freezer an increase in LDH3 activity was recorded. Experiment 2. Serum samples were kept in water baths for 30 min. at 50, 53, and 56°C. A simultaneous and increasing loss in activity of LDH3, LDH4, and LDH5 was seen from 50° to 56°C. At 56° no activity was left in LDH3, LDH4, or LDH5, and only about 15 % of the original activity was present in LDH2. LDH1 showed no loss at 56°, but all activity was lost at 65°. A close correlation was found between total lactate dehydrogenase and α-hydroxybutyrate dehydrogenase activity in both experiments.     

Stability of Some Serum Enzymes in Sheep,Cattle, and Swine During Storage at Different Temperatures

Owing to the increased use of serum enzyme determinations in veterinary diagnostic work, greater knowledge about the keeping qualities of different animal sera under various storing conditions seems desirable. The present paper deals with the stability of serum aspartate aminotransferase (AspAT = GOT), alanine aminotransferase (A1AT = GPT), lactate dehydrogenase (LDH), and a-hydroxybutyrate dehydrogenase (HBD) in cattle, sheep, and swine. Sera from 14—16 animals of each species were analysed daily for 5 days after storage at room temperature (22°C) and in the refrigerator (4°C). Samples kept in the deep-freezer (—20°C) were reanalysed once after 32—38 days. Significant differences of serum activity were found between individuals for all enzymes in the three species. Great variations were found in the stability of enzyme activities of different species. To summarize, it may be said that the changes of transferase activities were less pronounced under the different storing conditions than those of the dehydrogenases investigated. Pig serum in particular showed heavy losses of the latter enzymes already after 1 day, more pronounced at refrigerator than at room temperature. As a consequence of the results obtained, practical recommendations for analytical work on these enzymes are suggested.     

不同硬实程度乌拉尔甘草种子的活力差异

根据乌拉尔甘草种子吸胀时间的长短将种子硬实程度分为H0、H1、H2、H3、H4和Hmax6个等级,测定其活力指标;同时于盐胁迫和水分胁迫下测定硬实和非硬实种子的发芽率、发芽指数、胚根长度及幼苗的抗氧化酶活性。结果表明:随着硬实程度的增大,种子的发芽率、发芽指数、胚根长度、脱氢酶活性和ATP含量均呈上升趋势,丙二醛(MDA)含量则表现出下降趋势;在逆境条件下,硬实种子比非硬实种子的适应能力强。硬实种子的活力高于非硬实种子,硬实程度与种子活力呈正相关。     

Changes in Photosynthesis in Inbred Maize Lines with Different Degrees of Chilling Tolerance Grown at Optimum and Suboptimum Temperatures

The effects of growth temperature on changes in net photosynthetic rate (PN) and the chlorophyll fluorescence induction parameter Fv/Fm were investigated after cold stress in inbred maize lines with different degrees of cold tolerance. There was no significant difference between lines grown at optimum temperatures of 25/23 and 20/18 °C as regards PN and Fv/Fm determined at the growth temperature, but these parameters were lower for plants grown at a suboptimum temperature of 15/13 °C. After cold treatment, the decrease in PN was more pronounced in chilling-sensitive lines. The higher the growth temperature was, the more pronounced decrease occurred in PN and Fv/Fm. Thus at low growth temperature both damaging and adaptive processes occur.     

Optimum Initial Inoculum Levels for Evaluation of Resistance in Tomato to Meloidogyne spp. at Two Different Soil Temperatures

The effects of Meloidogyne incognita or M. javanica at five initial inoculum levels of 20, 100, 200, 1,000, and 2,000 eggs and infective juveniles per seedling on ''Floradade,'' ''Nemarex,'' ''Patriot,'' and ''PI 129149-2(sib)-5'' tomatoes maintained at 25 or 32.5 C were studied. The number of egg masses on roots of the susceptible cultivar Floradade was similar for both species of root-knot nematodes at either 2.5 or 32.5 C soil temperatures. At 25 C, very low numbers of egg masses were produced by both species of root-knot nematodes on Nematex, Patriot, and Lycopersicon peruvianum PI 129149-2(sib)-5. At 32.5 C, the best inoculum level for assessing resistance in these tomato genotypes was 200 eggs and infective juveniles per seedling. With 28 days of incubation, this temperature and inoculum level produced quantitative differences in resistance for both species of Meloidogyne.     

Changes in Properties of Malate Dehydrogenase Isolated from Solanum nigrum L. Seeds Imbibed at High Temperatures

Exposure of Solanum nigrum L. seeds for 48 h to high temperature(50°C) during imbibition, lowered considerably the activityof malate dehydrogenase in the mitochondria and in the cytosol.The affinity of both isozymes for their substrates and co-enzymeswas strongly depressed by this treatment. Optimal pH and optimaltemperature for maximal specific activity were also changed.Enzyme from treated seeds, although much less active, was moreheat tolerant. Separation on a DEAE cellulose column showedtwo distinct peaks of activity for cytosolic malate dehydrogenasefrom both treated and control seeds. Gel filtration througha G-75 Sephadex column showed only one peak of activity in bothcases. Gel electrophoresis of s-MDH from control seeds showedtwo bands of enzyme activity for each of the peaks eluting fromthe DEAE column. Only one activity band could be detected forenzyme from heat treated seeds and this band corresponded toone of the activity bands found in the control. From analysisof the data it appears that while part of the enzyme was denatured,due to exposure of the seeds to 50°C, a conformational changein the other part of the enzyme might have occurred which resultedin a change of enzyme properties and activity. However, on thebasis of the reported results an induction of synthesis of anew ‘heat tolerant’ enzyme, due to the treatment,cannot be ruled out. Key words: Solanum nigrum L., malate dehydrogenase, heat treatment, seeds     

Seed Germination Studies. III. Properties of a Cell-free Amino Acid Incorporating System From Pea Cotyledons; Possible Origin of Cotyledonary α-Amylase

Pea cotyledonary alpha-amylase increases dramatically both in specific activity and total activity between days 7 to 10 when germination occurs in the dark. This enzymatic activity does not seem to appear as a consequence of release or formation of an activator, removal of an inhibitor, dissociation of an inactive amylase complex, or proteolytic decomposition of a zymogen precursor. The possibility remains that the alpha-amylase is newly synthesized during germination. The preparation and properties of a cell-free protein-synthesizing system from germinating pea cotyledons is described; polyuridylic acid must be added for l-phenylalanine incorporation. Active microsomal preparations can be obtained from cotyledons germinated 10 days.     

Phytochrome and Seed Germination. III. Action of Prolonged Far Red Irradiation on the Germination of Tomato and Cucumber Seeds

Prolonged irradiation with continuous or intermittent far red prevents the germination of tomato and cucumber seeds. The inhibitory efficiency of intermittent far red decreases with the lengthening of the interval between successive irradiations, and with the increase of temperature. If each far red irradiation is followed by red, germination is restored. Intermittent far red is less inhibitory than intermittent red-far red when red is given immediately before each far red. This effect is more evident when the interval between successive irradiation becomes longer.