We investigated the effect of pre and post-cryopreservation treatment on the dehisced Ginseng (Panax ginseng C.A. Meyer) seeds germination rate. All seeds covered with endocarp and 96.3% of them were opened, initial moisture content (IMC) and germination rate were 55.9% and 84.0%, respectively. According to the pre and post-cryopreservation methods, highest seeds germination rate (GR) was observed in non-precooled seeds which recovered at 40°C, in which MC was 8-12% and desiccated at 15℃. However, by prolonged drying the seeds GR comparatively decreased under MC of below 2.2%, reaching below rate 4% regardless of pre and post-cryo treatments, whereas the seeds dried at 25℃ airflow cabinet saved significantly high rate. The effects of desiccation and of cryopreservation on the survival and developmental pattern of roots and stems showed that the earliest appearance of the root in control seeds was detected after 10 days of bedding in GA medium, and the stem started to develop later on the third week of germination test. And, on the 30th day of the investigation stem growth rate significantly increased and showed equivalent data with root rate. Almost the same pattern showed the seeds after cryopreservation, but it significantly delayed in the development compared to control, where term of the investigation continued till 40 day than control 30 day. Additionally, non-precooling seeds in both desiccation and recovery methods were showed high root and stem growth compared to precooled treatments.
BACKGROUND:The scab, which is caused by Venturia nashicola, gives serious damages to pear trees. 'Niitaka'
Identification of heat tolerance trait in pepper genotypes is an important for the breeding of heat tolerant cultivars in pepper. Therefore, in the present study were investigated effect of heat treatment (HT) on morpho-physiological and biochemical status of two commercial pepper cultivars “Chyung Yang” and “New Bigarim” in seedling stage and their post-treatment reproductive ability. The seedlings with 8-10 true leaf stage were maintained at day and night temperature of 42°C for 10 days and cv. “Chyung Yang” were identified as a heat tolerant and “New Bigarim” as a susceptible to heat stress. The HT survival were revealed during 5 days and the threshold of heat tolerance were determined within 10 days of treatment among cultivars. We found no significant relation between leaf heat damage levels (LHD) with chlorophyll content (CHL). During HT were identified significant reducing of the biomass of seedlings, whereas the photosynthetic rate (PN), intercellular CO2 concentration (Ci), stomatal conductance (Gs) and transpiration rate (Tr) values were increased than in normal treatment (NT) seedlings. The cell membrane thermostability values were not steady during HT and in heat treated seedlings at recovery stages, where electrical conductivity (EC) rate showed of the increasing in seedlings at HT than NT. Total free proline content (PRL) significantly increased in HT stressed seedlings over NT on day 5 of treatment, when survival of seedlings were finished. In both cultivar plants with different LHD were identified the significantly increasing of PRL than NT plants at recovery, where the mean fold increase within 2-3 times than in seedlings which were exposed to the HT. LHD significantly effected on reproductive growth stage, where LHD levels over 25% was critical for plants recovery. There no identified the any significant the linkage of heat tolerance in seedling stage with reproductive growth stage, where cv. “Chyung Yang” was determined as a heat tolerant in seedling stage but in reproductive stage it showed negative index of agronomical traits.
-We compared the germination rate of dehisced ginseng (Panax ginseng) seeds that were dried under two different conditions, slowly at 15℃ [relative humidity (RH) 10-12%] and rapidly under a laminar airflow cabinet at 25℃ (RH 22-25%). The measurements showed that drying rate and seed moisture content (SMC) play important roles in storage ability and vigor. The seeds that were dried rapidly at 25℃ showed high GR compared with the seeds that were dried at 15℃ after 6 and 12 months of storage at -80℃ irrespective of MC. Seeds dried slowly at 15℃ with MC higher than 7.0% showed high GR maintenance after storage at -18℃ and at 4℃ in comparison with rapidly dried seeds. However, the GR of the slowly desiccated seeds decreased as mean SMC was reduced to less than 5.0%, whereas the rapidly dried seeds were distinguished by significantly high GR irrespective of the storage conditions. The ginseng seeds desiccated under different conditions showed differences in storage performance. Seeds with 7-9% MC that were dried slowly at 15℃ for 5-7 days showed high GR after 4℃ and -18℃ storage; however, longer periods of desiccation decreased the germination level remarkably compared with that of rapidly dried seeds.
The purpose of this study was to investigate responses of pear cultivars 'Niitaka' and 'Chuwhangbae' under short period heating on cold resistance level of flower buds. Experiment was conducted using annual shoots flower bud which were artificially heated (AH) during 72 hour at room condition (18-20℃). To assay for cold resistance, the cultivars were treated and observed under negative temperatures-10,-15,-20 and-25℃ during the winter period in 2012 and 2013. Our findings revealed that 'Chuwhangbae' which was treated under control and artificial heating treatments was more resistant to low temperature than 'Niitaka' showing decreasing level of flower buds damages by mid-January although in early March an increasing level of damages was observed again. Cold resistant cultivar 'Chuwhangbae' responded more sensitively to external environments. This means that 'Chuwhangbae' restructures the plant protoplasts and process the transition to the new metabolic energy level in an efficient manner when triggered by effective negative temperatures thereby resulting in hardening process. We assume that this might be closely related with dormancy period, concentration of the mineral elements, water potential and transition processes of metabolism to the new energetic level. With a rise in temperature, cold tolerance in pear cultivars significantly decreased and this is related to intensive development of the floral organs. The chilling requirements for blossoming of 'Niitaka' was higher than 'Chuwhangbae'.
This study was conducted on screening for 21 pepper genotypes tolerant to low temperature and their duration for survival in 3-4 (38 days after sowing), and 4-6 (47 days after sowing) true leaf seedling growth stages (LS). It was detected that response of seedlings on low temperature were different and ranged among the genotypes depends on growth stages. Seedlings in early 3-4 LS growth stage were more susceptible than 4-6 LS seedlings, where the first symptoms of leaf cold damages (LCD) were revealed within 7 days after transplanting (DAT) and 12 DAT in pepper seedlings, respectively. There were identified that the susceptible genotypes in 3-4 LS can be tolerant in 4-6 LS, or show opposite pattern, where tolerant one in next the growth stage, plant becomes susceptible. Low temperature negative impact on chlorophyll content (CHL) in leaves, however depends on seedling growth stage and genotype might be ranged. The lowest content of CHL were observed in early growth 3-4 LS seedlings than 4-6 LS. And, it was revealed that cold susceptible pepper genotypes in which CHL reduced significantly during cold treatment, showed good ability to recovery of CHL after treatment of seedlings in NT condition, whereas cold tolerant genotypes with high CHL content during low treatment, can reduce significantly of CHL after transfer of seedlings to NT condition for recovery. According to screening were selected relatively cold tolerant pepper genotypes LT8 and LT9 in early 3-4 LS, and LT8, LT13, LT18, LT20 and LT21 in 4-6 LS, where LCD were below 45 and 10%, respectively.
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