Physiological characteristics changes of Aesculus chinensis seeds during natural dehydration

A study was conducted to determine the physiological characteristics changes of Aesculus chinensis seeds during natural dehydration in 2003. The results showed that A. chinensis seeds were recalcitrant with being highly desiccation-sensitive. The seed moisture content of fresh fruits was higher than 60%. When the seeds were naturally dried for 30 days, their moisture content declined to 30.2% and their viability was completely lost. The seed germination percentage had a small increase at the beginning of desiccation and then decreased rapidly. The relative electrical conductivity of the A. chinensis seeds increased along with a decrease in seed moisture content. However, there was an abnormal increase in relative electrical conductivity when the seed moisture content was between 53.7% and 50.9%. Superoxide dismutase （SOD） activity decreased rapidly in the period of desiccation except for an abnormality when the seed moisture content was between 53.7% and 50.9%. Malondialdehyde （MDA） content increased slowly at the early stage of desiccation and then rose rapidly after the moisture content was below 50.9%. The soluble sugar content in seeds slowly increased with the increasing period of desiccation. The seed germination percentage was at the high level when seed moisture content was in range of 47%- 60%, which suggests that this was the optimum moisture content for maintaining A. chinensis seed viability.

Effect of seed priming with different concentrations of potassium nitrate on the pattern of seed imbibition and germination of rice(Oryza sativa L.)

Low germination and vigor of rice seed associated with dry-seed broadcasting are common problems encountered by rice growers.The objectives of this study were to evaluate the role of potassium nitrate（KNO3）on the pattern of seed imbibition and to determine the effect of seed priming with KNO3 on the germination percentage,speed and uniformity of germination in rice seed.Experiment 1 compared the patterns of seed imbibition of six concentrations of KNO3（0,0.25,0.50,1.00,1.50,and 2.00%）in two rice cultivars-KDML105 and RD15.The results showed that soaking rice seed in KNO3 at higher concentrations could delay the imbibition time.The higher concentrations of KNO3 delayed the imbibition time of rice seed and took a longer time to reach the end of phases 1 and 2 compared to the lower concentrations.The patterns of seed imbibition using distilled water of both rice cultivars（KDML105 and RD15）were quite similar,but with different concentrations of KNO3,the imbibition time taken to reach the end of phases 1 and 2 was slightly postponed in KDML105 suggesting that different rice cultivars may need different imbibition times for soaking seed in the priming process.Experiment 2 evaluated the effects of seed priming with 1.0 and 2.0%KNO3 at different imbibition times.It was found that priming with 1.0%KNO3 showed better seed germination than priming with 2.0%KNO3 and seed priming with 1.0%KNO3 at the imbibition time of early phase 2（or 28 h for KDML105）improved seed germination and increased both the speed and uniformity of seed germination.The results of this study show promise for the use of priming with 1.0%KNO3 soaked until early phase 2 of seed imbibition for improving the seed germination and vigor of rice in dry seed broadcasting.

Variations in seed germination ofHippophae salicifolia with different presoaking treatments

Mature seeds of H. salicifolia, collected from five provenances （i.e. Hanuman Chatti, Helang, Lata, Rambara and Janggal Chatti） in west Himalaya, India, were treated with stratification （at 4℃ for 15, 30 and 60 days） and in different concentrations of GA3 （5, 10, 20 mM）, KNO3 （50, 100, 200 mM） and Thiourea （50, 100, 200 mM） solution to determine the variations in seed germination. Results reveal that the germination rates of seeds from different provenances under different pre-sowing treatments are significantly increased compared to those in control （24%-30%）. The seeds treated with Thiourea （100 mM） have highest germination rate （76%-83% for different seed sources）, followed by those （63%-71% for different seed sources） pretreated with stratification （4℃, 30 days）. GA3 treatment significantly shortens the mean germination time （MGT） and improves seed germination percentage. Considering the practical applicability and cost effectiveness, thiourea （100 mM） and stratification （at 4℃） treatments for seed germination are recommended for mass multiplication through seeds of H. saliciifolia in village/forest nurseries of the west Himalaya, India.

Effects of temperature and light on seed germination of ephemeral plants in the Gurbantunggut Desert, China: implications for vegetation restoration

Seed germination is a key transitional stage in plant life cycle and is strongly regulated by temperature and light.Therefore, research on the effects of temperature and light on seed germination is extremely meaningful for vegetation restoration, especially in desert ecosystems.Seeds of 28 ephemeral plants collected from the Gurbantunggut Desert of China were incubated at different temperatures(5℃/1℃, 15℃/5℃, 20℃/5℃, 25℃/10℃ and 30℃/15℃) in 12-h light/12-h darkness or continuous darkness regimes, and the responses of seed germination to temperature and light and the germination speed were studied in 2016.Results showed that seed germination percentage of the 28 ephemeral plants significantly differed to temperature and light.We classified the studied plants as the following groups based on their responses to temperature: 1 low temperature responsed plants, 12 moderate temperature responsed plants, 7 high temperature responsed plants, 4 non-responsed plants and 5 plants of no germination.It should be noted that Corispermum lehmannianum Bunge is sensitive to both moderate and high temperatures.There were 4 groups of plant in response to light, i.e., 7 light responsed plants, 10 dark responsed plants, 6 light non-responsed plants and 5 plants of no germination.Based on seed germination speed of the 28 ephemeral plants, we divided them into 4 patterns of germination, i.e., very rapid, moderately rapid, moderate and slow.Combining variations of temperature, precipitation and sand dune types in the study area, we suggested that very rapid and moderately rapid germinated plants could be used to moving sand dunes in early spring during vegetation restoration, moderate germinated plants could be used to semi-fixed sand dunes in late autumn, and slow germinated plants could be used to sand plain in summer.Thus, seedling establishment and vegetation restoration would be improved by considering seed germination characteristics of these ephemeral plants in the Gurbantunggut Desert, China.

The coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds

Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds,we set up three light conditions(L200:200μmol m^(-2) s^(-1),L20:20μmol m^(-2) s^(-1),L0:0μm^(-2) s^(-1))and four storage temperatures[T-5:-5°C(50 days),T5:-5°C(50 days)+5°C(50 days),T25:-5°C(50 days)+5°C(50 days)+25°C(50 days),T15:-5°C(50 days)+5°C(50 days)+25°C(50 days)+15°C(50 days)]using imbibed seeds,then quantified phytohormones gibberellic acid(GA_(3))and abscisic acid(ABA)during the stratification.Germination percentage(G_(P)),mean germination time(T_(M)),and germination value(G_(V))under 25/15°C temperature and the three light conditions were then determined.Phytohormone levels and germination performances were significantly affected by light and temperature.No consistent trend was found between the phytohormone levels and G_(P) caused by light levels.Under the three light conditions,ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15;GA_(3) decreased in nearly all four storage temperatures.G_(P) reached 40–60%in T25 storage without light irradiance.In the three light conditions,G_(P) and G_(V) were higher at T5 and T25 than at T-5 and T15;so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination.At optimum temperatures,light(L200,L20)significantly increased the G_(P) and G_(V) compared with the dark(L0).At L200 and L20,significant negative correlations between G_(V) and the ABA concentrations and positive correlations between G_(V) and GA/ABA in the seed embryo were found.Temperature played a more important role in primary dormancy release and germination;light was unnecessary for primary dormancy release.Light facilitated seed germination at optimum temperatures.The dormancy release and germination of P.koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.

Effect of Moisture Content on Melilotus suaveolens Seed Quality During Ultra-drying Storage

In order to enhance the seed storability and supply high-quality seeds for vegetation restoration in the arid and semi-arid regions in Northwest China,the effects of ultra-drying and accelerated aging on the physiological characterstics of Melilotus suaveolens seeds were studied.Melilotus suaveolens seeds were dried in a desiccator containing silica gel to 80,53,42,33,23 and 16 g·kg-1 of moisture contents（MC）,respectively.The parameters of the seed quality including germination energy（GE）,germination percentage（GP）,relative conductivity（RC）,dehydrogenase activity（DA） and α-amylase activity（AA） were determined after ultra-drying and accelerated aging.The results showed that ultra-dried seeds with 42 g·kg-1 of MC showed the minimum changes of GE and GP before and after seed aging.Moreover,ultra-dry seeds with 42 g·kg-1 of MC showed higher DA and AA,and lower RC than non-ultra-drying seeds.Therefore,ultra-drying to 42 g·kg-1 of MC was helpful for M.suaveolens seed storage.

Ribbed towel gourd seed germination

The influence of different conditions on ribbed towel gourd seed germination was tested in this paper. Results showed that the seeds germinating energy and germination percentage were increased evidently under the treatment of dipping in normal water temperature for 4 hours and drying out for 1 hour at 30℃.

Germination of Seeds of Interspecific Hybrid Caiaue×Oil Palm Submitted to the Mechanical Depulping

Oil palm seeds respond well to protocols of dormancy break, however, the seeds of interspecific hybrid (HIE) (caiaué × oil palm) have lower germination rates. The mechanical depulping can affect the potential of germination of seeds, therefore the objective of this study was to evaluate the mechanical depulping on the seed germination, vigor and viability of embryos HIE BRS Manicoré. A randomized block design with five treatments, based on the depulping time and on the percentage of mesocarp on the seed with four replications was used. The percentage of seed germination, the germination speed index (GSI), the percentage of fungi and abnormal seeds and vigor and viability of embryos were evaluated. There was no statistical difference (p < 0.05) between treatments for all variables. The average of germination at 35 days was 45.34% and embryos showed high to medium vigor by the tetrazolium test. The mechanical depulping do not affect the seed germination, nor the viability and vigor of embryos HIE BRS Manicoré. It is recommended that the fruits of HIE BRS Manicoré remain in depulper machine for 40 minutes to completely remove the mesocarp residue.

Study of Ultra-drying on Vigor and Physiological Characteristics of Lespedeza bicolor Seeds

Ultra-drying (in a desiccator with silica gel) and accelerated aging (50 oC, 30 d) of Lespedeza bicolor seeds from the arid and semiarid areas of northwest China were studied. The results showed that in the moisture content of seed ( 43?70 g/kg), germination percentage and vigor indices had no significant differences; ultra-dried seeds had a stronger anti-aging ability than those with natural drying, and the best MC for the storage was 43 g/kg. Therefore, it was feasible to store L. bicolor seeds with ultra-dried moisture content.