Effects of after-ripening,stratification and GA3 on dormancy release and on germination of wild asparagus (Asparagus acutifolius L.) seeds

Seeds of wild asparagus (Asparagus acutifolius L.) were treated and compared in this research to investigate seed dormancy class and level involved in this species. Four seed lots were compared: (i) freshly harvested seeds in 2007 (07Fr); (ii) freshly harvested seeds in 2008 (08Fr); (iii) after-ripened (AR) 2007 seeds dry stored in glass jars (ARg); (iv) AR 2007 seeds dry stored in paper bags (ARp). The 07Fr seeds were exposed to (1) chemical scarification combined with gibberellic acid (GA₃) levels (0, 200, 400, and 600 mg L⁻¹) and to (2) 28-day moist stratification at 5 and 23 °C, and two sequences of 5/23 °C combined with 0 and 400 GA₃ mg L⁻¹ levels, and (3) together to the 08Fr and AR seeds were exposed to 56-day moist stratification at 5, 23, or 5/23 °C. With the 08Fr and AR seed lots this last stratification treatment was combined with 0 or 800 GA₃ mg L⁻¹ levels. The dormancy depth of 08Fr (32% germination) was less than 07Fr seeds (2%). The latter after-ripened during dry storage and when stored in glass germinated more (47.5%) than in paper (12%). Stratification for 4 weeks was ineffective in improving germination of 07Fr seeds; when chemically scarified they did not germinate at all. The highest (nearly 70%) and the most rapid and uniform germination were observed for all the lots when they were warm stratified for 56 days. Warm stratification improved germination more than alternate temperature stratification, while cold stratification inhibited germination especially for the 08Fr and ARg lots, thus seeds seem not to have a morphological component to their dormancy. GA₃ only improved germination of 07Fr seeds, at a low rate. A. acutifolius seeds fit the characteristics of a non-deep physiological dormancy.     

Methods to break seed dormancy in Cyclocarya paliurus (Batal)Iljinskaja

Cyclocarya paliurus is native to China and is the sole species in its genus. However, the seeds remain deeply dormant for 2 years in their natural environment. We tested different pretreatments of chemical scarification and exogenous application of gibberellic acid (GA₃) for efficacy in breaking dormancy and speeding germination. In contrast to scarified seeds, non-scarified seed did not germinate, indicating that C. paliurus seeds have hard, impermeable seed coat dormancy. Exogenous application of GA₃ significantly enhanced germination of scarified seeds. Compared with seeds stratified in sand with water, the germination of seeds stratified in sand moistened with 400 ppm GA₃ for 60 days was significantly increased and germination rate was over 90% after 120 days. Analysis of variance indicated that both GA₃ concentration and stratification medium had significant effects on seed germination and final germination percentage. Germination was higher for longer stratification periods, but no significant difference in germination was observed after 90 days. These results suggested that C. paliurus seeds exhibit both exogenous and endogenous dormancy. A combination of chemical scarification and exogenous application of GA₃ alleviated seed dormancy in a relatively short period of time.     

Effect of stratification temperature,stratification period and seed coat on seed germination of peach cultivar ‘Sharbati’

Freshly harvested seeds of peach cultivar ‘Sharbati’ were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. 10° C stratification was found to be the best for breaking seed dormancy. Increased seed germination was recorded when the seeds were after-ripened without seed coats as compared to the seeds after-ripened with seed coats. There was no further increase in germination when seeds without seed coats were stratified beyond 60 days at 10° C, while a significant increase was recorded up to 75 days of stratification in the case of seeds with seed coats. Unstratified seed coats, soaked in water for 72 h, leached out a water-soluble inhibitor, which could suppress the germination of stratified peach seeds without seed coats. When this leachate was bioassayed by a cress-seed germination test, it showed the presence of an inhibitor at Rf 0.7-0.9. Hence, delayed germination of seeds with seed coats may be due to the presence of an inhibitor in seed coats.     

Physical dormancy in myrtle seed

The nature of dormancy in seeds of myrtle (Myrtus communis L.) was investigated. Scarification with cold acid or sand paper and soaking in water increased seed germination, whilst stratification, inserting the seeds in boiling water or hot acid treatment decreased the number of germinating seeds. The highest germination was obtained by treating the seeds with 100 % cold acid for 60 min or 80 % cold acid for 120 min. Hard seed coat was found to be the principal cause of poor seed germination.Scarified and non-scarified seeds were germinated for 2 weeks at 6 temperatures between 5 and 30° C, and 20° C was optimum.     

Effects of Pre-Stratification Storage Conditions on Black Walnut Seed Post-Stratification Germination Capacity

The objective of this work was to quantify changes in the germination capacity of Juglans nigra seeds following storage and then artificial stratification. Seeds were stored at 5 and –20 °C under 5% and 14% internal moisture content (IMC) for 0, 8, 10, and 12 months under conditions with oxygen or under vacuum. Germination percentage (GP) was affected by storage temperature, IMC, and storage period. Seeds stored with 5% IMC succeeded in germinating regardless of the temperature. Seeds stored with 14% IMC did not germinate (–20 °C) or germinated during storage (5 °C). The GP was reduced with the time of storage in seeds at –20 °C and 5% IMC and this effect was avoided in storage under vacuum. In conclusion, the germination capacity of black walnut seeds did not change for up to 12 months at low above-zero temperature and low IMC (5 °C, 5% IMC), being the most cost-effective alternative for long-term storage of black walnut seeds in commercial nurseries. Vacuum storage avoided the decrease of around 50% in average germination capacity of seeds stored for a year at –20 °C.     

The germination of watercress (Rorippa nasturtium- aquaticum) seeds. II. The relationship between seed colour and germination

Freshly-harvested seeds of green watercress were pale yellow, rapidly turning to pale brown under ambient laboratory conditions. Older seeds ranged from pale to very dark brown, the darker seeds losing more electrolyte than the pale ones when immersed in water. Dark seeds germinated more readily than pale ones when the seeds were freshly harvested, but with old seeds germination was generally greater with paler seeds than darker ones. The results suggested that darkening of the seed coat was associated initially with a loss in dormancy and ultimately a loss in viability. Darkening of the seeds was enhanced by moisture. It could be induced by high humidity storage at 40°C, a treatment which resulted in increased electrolyte leakage from the seeds, or by holding individual seeds dormant at 35°C, although only the former treatment reduced germination. The results suggest that the ability of the seeds to germinate and the colour of the seed coat are not directly linked but that both are influenced by RH and temperature during storage.     

Seed dormancy and germination of Michelia yunnanensis (Magnoliaceae)

Michelia yunnanensis Franch. is a Chinese endemic ornamental shrub with potential for greater utilization as a landscape and medicinal plant if propagation was less difficult. Seed development and breaking of seed dormancy were investigated to improve propagation of M. yunnanensis. No fresh seeds germinated when tested at the time of dispersal. Newly matured seeds of M. yunnanensis contained differentiated linear underdeveloped embryos that were physiologically dormant. The embryo/seed length ratio of M. yunnanensis was 0.15. Warm stratification did not break seed dormancy. Dormancy was broken by cold stratification at 4 °C but not by flowing water or nitrate. Embryos developed grew inside seeds during cold stratification at 4 °C. In newly harvested dormant seeds, embryos were 0.94 mm long and increased in length 139% before radicle emergence (germination). GA₃ substituted for cold stratification to break dormancy in seeds of M. yunnanensis incubated at 25 °C or 20/25 °C. Mature M. yunnanensis seeds exhibited intermediate complex morphophysiological dormancy. Optimal germination of non-dormant seed in terms of both germination percentage and rate occurred at 20/25 °C.     

Seed germination and seedling vigour of transgenic tobacco (Nicotiana tabacum L.) with increased proline accumulation under osmotic stress

Proline plays important roles in various stages and processes of plant development. However, there are few reports on the effect of endogenous proline accumulation on germination and seedling vigour under suitable conditions of germination and development. The aim of this work was to evaluate the effect of endogenous proline in transgenic tobacco (Nicotiana tabacum L.) constitutively expressing the VaP5CSF129A gene in germination and seedling vigour. Under optimal conditions of germination, the transgenic seeds had high proline content when compared to the non-transgenic plants. However, this higher accumulation did not result in better germination or seedling vigour, contrasting to reported results for exogenous proline application. The pre-treatment by water submersion indicated that the lowest initial seed germination with the highest proline concentration may be due to their greater post-harvest dormancy. When newly germinated seedlings were subjected to osmotic stress (?0.9 MPa), the free proline content increased proportionally in all genotypes and the transgenic events seedlings showed greater root length compared to those of the non-transformed control. This can be advantageous as, in theory, seedlings with longer roots may have a better chance of growing and exploring the different soil layers, allowing the transgenic events to be more tolerant to edaphic constraints.     

The Effect of Scion on Root.: II. Stem-Worked Apples.

Summary

The effects of seed coat removal and chilling on the germination of seeds of ten cultivars of ornamental peach (Prunus persica Batsch) were investigated. Seeds were rinsed in running tap water for 48 h in order to facilitate seed coat removal. Only a few non-chilled, intact seeds germinated (e.g., 6% of ‘Hito’ seeds). Seed coat removal and no chilling resulted in some seed germination in eight of the ten cultivars, ranging from 6% to 83%. Chilling intact seeds at 5°C for up to 10 weeks resulted in greater frequencies of germination (average = 85% germination) than seed coat removal before (average = 80%) or after chilling (average = 73%). There was a linear decrease in the germination percentage with an increase in abscisic acid (ABA) content for ‘Yaguchi’,‘Kanpaku’, and ‘Kikumomo’ seeds (R = –0.66; P <0.001). The most consistent decrease in total seed ABA content (average of 64%) occurred during the 48 h rinsing period. In ‘Kanpaku’, dry seeds had an intermediate ABA content (13 ng per seed); but, in the embryonic axes, this increased from 0.03 ng to 1.2 ng per seed with an increase in the duration of the chilling period. The lowest germination percentages were found in this cultivar. These results suggest that ABA synthesis in the embryonic axes during chilling may affect the varietal characteristic of seed dormancy, and that rinsing seeds for >48 h could remove sufficient ABA to allow seed germination with minimum chilling.     

Mini-Nut Propagation Technique of Kola (Cola nitida, (Vent.) Schott and Endl.): Prospects for Germination and Propagation of Kola Plantlets in the Pre-Nursery

Limitations against propagation of Cola nitida include pronounced dormancy of between 1 and 8 months after sowing (MAS) leading to uneven germination and seedling growth. This experiment was conducted in a screenhouse, Federal University of Agriculture Abeokuta, Nigeria, to evaluate the effects of mini-nut and nut-color on germination and seedling growth of C. nitida nuts. The experiment was in a completely randomized design replicated 3 times. Treatments comprised two factors: nut/seed-colored biotype (white, pink, and red) and mini-nut (embryonic portion of cotyledon) [excised embryonic portion cotyledon (EEPC), 25% embryonic portion cotyledon (EPC), 50% EPC, 75% EPC, and 100% EPC (whole nut/seed)], giving 15 treatment combinations sown in plastic cups of 50 cl filled with sawdust. Germination percentage and morphological growth of plantlets (plant height (cm), number of leaves, dry matter yield (g/plant)) were monitored; data subjected to analysis of variance and mean comparisons done (p ≤ 0.05). As early as 4 WAS, the EEPC and 25% EPC had 67.78% and 54.44% germination, respectively. Within the same period, 51.33%, 48.00%, and 31.33%, respectively, of white-, pink-, and red-colored seeds germinated. At 6 WAS, the white-, pink-, and red-colored seeds had mean germination of 80.67%, 92.00%, and 72.67%, respectively. At 12 WAS, germination was observed to complete with the pink-, red-, and white-colored nuts having 97.33%, 92.61%, and 91.33%, respectively. Within the same period, the mini-nut sizes had between 92.22% and 95.56% germination. Combining the two factors, 50% EPC, 25% EPC, and EEPC of white-nut biotype germinated earliest with 50.00–76.67% at 4 WAS and 73.33–80.00% at 5 WAS. The EEPC of pink-colored biotype attained 100% at 6 WAS, while other treatments were between 56.67% and 93.33%. Thus, while earliness in germination pattern follows the order: EEPC > 25% EPC > 50% EPC > 75% EPC > whole nut, the plantlet morphological growth followed a reverse order. With mini-nut technique therefore, timely and even germination of kola nuts were obtained and 50%EPC would be recommended for conventional propagation while EEPC would require nutrient amendment for improved growth.     

Seed germinability in Musa velutina Wendl. & Drude is markedly lowered by 1 week in dry-storage

SUMMARY

We investigated the effects of dry-storage of Musa velutina seeds on seed and embryo germination. Seeds were collected immediately after harvest and stored in dry vermiculite at 25°C, in the dark, for 0, 1, 2, or 4 months. The germinability of dry-stored seeds was assessed by incubation in vermiculite at 25°C for 4 months, with 75% [(w/w); –0.01 MPa] moisture content to promote embryo development in viable seeds. Seeds that had not been dry-stored and stored in vermiculite at 75% (w/w) moisture content for 4 months showed 90% germination by 20 d after sowing, but no seeds that had been dry-stored for longer than 1 month germinated. Seeds were also dry-stored at 25°C, in the dark, in Petri dishes for 0, 1, 2, 3, or 4 weeks after harvest and the embryos removed from these seeds were cultured on MS medium. All embryos that had been isolated from seeds at harvest (i.e., 0 weeks in dry-storage) germinated during embryo culture. However, embryos removed from seeds that had been dry-stored for 1 week showed a substantial decrease in both size and germinability. Seeds were also stored at different moisture contents for 4 months after harvest. No seeds that had been stored at 0% moisture content (i.e., dry) germinated, but > 85% of seeds stored at ≥ 25% (w/w) moisture contents germinated. Higher moisture contents increased the uniformity of seed germination, showing that M. velutina seeds rapidly lose their germinability through dehydration, indicating that they are sensitive to desiccation.     

提高草莓种子离体培养发芽率的研究

该文以EMC、‘哈尼’‘丰香’‘北辉’等10份草莓为试材,研究了培养基质和种子处理对发芽的影响．以提高草莓种子的发芽率。结果表明：草莓种子处理、培养基质、品种等对发芽率、发芽速度有很大影响。种子整粒培养,栽培品种发芽困难,而野生品种发芽较容易,种子切开处理的,在不同的培养基质上,供试各品种的种子发芽率超过60％．最高达100％。培养基质以1,2MS＋3％蔗糖＋0．6％琼脂的为好,发芽率达90％以上。     

瓜类蔬菜种子休眠与萌发研究进展

破除瓜类蔬菜种子休眠的技术有机械损伤种皮、植物激素处理和化学药剂处理。多数休眠的瓜类蔬菜种子在特殊条件下能够发芽。瓜类蔬菜种子休眠的原因有胚休眠、种皮的障碍、发芽抑制物质的存在和激素不平衡等几个方面。     

Effects of seed maturity,seed storage and pre-germination treatments on seed germination of cleome (Cleome gynandra L.)

The influence of seed maturity, seed storage and germination pre-treatments on seed germination of cleome (Cleome gynandra L.) were investigated. Seed maturation studies showed that capsules harvested at 18 days after anthesis possessed the highest dry weight with 19.2% moisture and 1% germination. Development of fresh-ungerminated seed was observed with increasing maturity of fruit, suggesting that cleome exhibited forms of seed dormancy. Storing mature seed at 15 °C and at room temperature for 5 months showed that seed dormancy was broken after 3 months under both storage regimes. When mature seeds were subjected to different treatments including various levels of GA₃, KNO₃, leaching, pre-chilling, soaking and pre-heating at different temperatures, it was found that pre-heating at 40 °C for period of 1–5 days was the most effective method in breaking dormancy in cleome.     

海水胁迫对醴肠种子萌发的影响

为研究重要药用植物醴肠种子对土壤盐碱的耐受能力,利用不同浓度的海水胁迫处理醴肠种子,观察、分析海水胁迫对其萌发的影响.结果表明:醴肠种子的萌发需要光照,属喜光种子;1％以下浓度的海水对醴肠种子的萌发具有一定的促进作用,10％以下低浓度的海水,对醴肠种子的萌发率没有显著影响;综合发芽势与发芽指数2个活力指标,认为醴肠种子萌发时对3％以下浓度的海水具有一定的抗性.     

Effect of seed age,stratification, and soaking on germination of wild asparagus (Asparagus acutifolius L.)

Wild asparagus (Asparagus acutifolius L.) is a widespread species found in all the Mediterranean areas. The spears are highly valued by consumers and owing to its frugality, this species is a feasible new crop with high income potential, especially for Mediterranean marginal areas. Currently, the cultivation of this species is limited because of its low and erratic seed germination that makes difficult the production of seedlings for plant propagation. In this research, non-after-ripened (1 month-old) and after-ripened seeds (dry stored at room temperature for 13 months) were exposed for 30 days in the dark to three moist stratification treatments: cold (5 °C), warm (23 °C) or no stratification; subsequently they were soaked for 12 h in warm water (35 °C) or not soaked. The effect of these pre-germination treatments on three germination parameters (germination percentage, time to 50% of final germination – T₅₀ – and germination pattern) was studied, as well as some possible seed dormancy forms involved therein. The 1-year dry storage period proved to be effective in after-ripened seeds by enhancing seed sensitivity to the subsequent pre-germination treatments. After-ripened seeds exhibited higher and more rapid germination compared to non-after-ripened seeds. Soaking, cold or warm moist stratification had similar single effect on non-after-ripened seeds (27% germination). With after-ripened seeds, only soaking or warm stratification were effective (47% germination) when singularly applied, while cold stratification did not improve germination. By combining stratification and soaking treatments, a higher germination for both non-after-ripened and after-ripened seed-lots was achieved. The highest germination was obtained when after-ripened seeds were stratified and soaked (76%), without any significant difference between cold or warm stratification. Single or combined application of moist stratification (regardless of the temperature used) and soaking resulted always in a faster germination compared to that of no-treated seeds and especially with after-ripened seeds (T₅₀ = 6 days). A non-deep type 1 physiological dormancy can be hypothesized for the seeds of this species. Low stratification temperature induce secondary dormancy in after-ripened seeds that can be removed by soaking them at 35 °C for 12 h.     

Seed germination of seven pepper cultivars at constant or alternating high temperatures

Summary

Seeds of seven pepper (Capsicum annuum L.) cultivars (Anaheim TMR 23, California Wonder 300, Coronado, Jalapeno M, Ma Belle, Mercury, and Yolo Wonder B) were germinated at constant day and night temperatures of 25,30,35 and 40°C or at alternating temperatures of 40/25,40/30 and 40/35°C for 14 days. Germination percentages and rates were similar at 25 and 30°C. Largest differences in cultivar responses occurred at 35°C where germination percentages ranged from 24 to 96%, and rates, calculated as summation of the number of seeds germinated on a given day divided by day number, varied from 3 to 26 (theoretical maximum value of 100). At 40°C, germination percentages were less than 5% and rates were less than one for all cultivars. Cultivars with the most heat tolerance were ‘Mercury’ and ‘Yolo Wonder B’. At alternating temperatures, germination percentages and rates were higher than those at constant 40°C. The increases were greatest when the temperature was lowered by 15°C (40/25°C) and least when temperatures were lowered by 5°C (40/35°C). Tetrazolium tests showed that a large percentage of the ungerminated seed was still viable from the highest temperature. At lower temperatures, fewer ungerminated seeds were viable with no viable ungerminated seeds from the lowest temperature.     

聚乙二醇胁迫对高羊茅种子萌发和幼苗生长的影响

采用不同浓度聚乙二醇(PEG6000)溶液,对‘星火’、‘可奇思’、‘猎狗六号’3个高羊茅种子的萌发情况进行研究。结果表明:3个品种在干旱胁迫下种子萌发时间并无显著差异,且在高浓度时均未发芽。低PEG浓度(5%)对‘猎狗六号’和‘星火’种子发芽有促进作用,高浓度(15%～25%)对3个品种种子的萌发都表现为抑制作用。3个品种的抗旱性顺序为‘星火’>‘猎狗六号’>‘可奇思’。     

The effects of pre-sowing seed treatments on the germination and emergence of lettuce seeds at high salt concentrations

Radicle emergence in lettuce seeds cultivar ‘Hilde’ was reduced by NH₄NO₃ above 8×10^?2M, while radicle extension was inhibited by 8×10^?2M NH₄NO₃ and no seedlings emerged. Inhibition of radicle emergence by 8 and 16×10^?2M NH₄NO₃ was prevented by soaking seeds for 4 h before sowing in a mixture of $\text{GA}{}_{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}$ and kinetin+phosphate buffer, and was partially prevented by soaking them for 4 h before sowing in phosphate buffer. These treatments did not prevent inhibition of radicle emergence by 32×10^?2M NH₄NO₃, but seeds soaked in growth regulators or phosphate buffer before sowing and taken from this NH₄NO₃ solution after 7 days and washed to remove excess salt gave 45–52% germination compared with 12 % for untreated seeds. Pre-treatment of the seeds did not prevent the inhibitory effect of NH₄NO₃ on radicle extension. In field experiments seeds treated with growth regulators + phosphate buffer or phosphate buffer alone gave a higher final percentage emergence from soils given 125 kg N/ha than did untreated seeds.     

Rapid seedlings regeneration from seeds and vegetative propagation with sucker and rhizome of Eremospatha macrocarpa (Mann & Wendl.) Wendl and Laccosperma secundiflorum (P. Beauv.) Kuntze

To develop efficient seedling production methods for Laccosperma secundiflorum and Eremospatha macrocarpa, a study was conducted to examine regeneration using offsets combined with several physical and chemical treatments of seeds. Offsets categorized into small, medium and large diameters, were planted in three conditions: shaded and open nursery, and greenhouse. We tested sucker from E. macrocarpa, and sucker and rhizome from L. secundiflorum. For both species, high viability percentage (ranging from 55% to 100%) were observed for small and medium suckers planted in shaded nursery and greenhouse, against less than 49% for sucker planted in open nursery. The mean seedling emergence times were estimated to 84, 77 and 75 days after planting (DAP) for small, medium and large sucker of L. secundiflorum, respectively under open nursery condition, and 76, 75, 95 DAP for small, medium and large suckers of the same species, respectively in shaded condition. Greenhouse has a significant positive effect on E. macrocarpa seedlings emergence time. For this species, the mean seedling emergence times were estimated to 43 DAP for small sucker and 76, 93 DAP for medium and large suckers. No seedling was obtained from rhizome planted in all the growing conditions tested. Concerning seed dormancy breaking, germination percentages and rates were determined for 13 treatments. The best treatments were pre-soaking unscarified seeds for 4 days in 1.01 g l⁻¹ and 0.10 g l⁻¹ KNO₃, with 79% and 68% of germination, respectively and in 3.46 × 10⁻³ g l⁻¹ GA₃ for 68% of germination. These methods are suggested to improve germination of L. secundiflorum seeds. Successful and recommended methods for E. macrocarpa are pre-soaking scarified seeds in 3.46 × 10⁻³ g l⁻¹ and 3.46 × 10⁻⁴ g l⁻¹ GA₃, 96% and 94% of germination, respectively. Dormancy, probably a combination of mechanical and chemical dormancy, is present in the two species.