The changes of chlorophyll_protein complexes and photosynthetic activities of chloroplast isolated from lotus ( Nelumbo nucifera Gaertn.) seeds germinating under illumination were studied. SDS PAGE analysis of c...The changes of chlorophyll_protein complexes and photosynthetic activities of chloroplast isolated from lotus ( Nelumbo nucifera Gaertn.) seeds germinating under illumination were studied. SDS PAGE analysis of chlorophyll_protein complexes showed that there was only the light harvesting chlorophyll a/b protein complex from PSⅡ (LHCⅡ) precursor in chloroplast from lotus seeds germinated for 2 to 6 days, while LHC Ⅱ 1, and the chlorophyll_protein complex of PSⅠ (CPⅠ) appeared on the 8th day of germination and PSⅡ reaction center complex appeared later. Studies on the polypeptides composition of the chloroplast revealed the following results: 1) Small amount of the 27 kD polypeptide was synthesized in invisible light; 2) The 30 kD polypeptide existed previously in the plumules of the dry seeds; 3) The amount of the 30 kD polypeptide was more than any other polypeptides before germination and decreased gradually throughout germination, while the 27 kD polypeptide changed in the opposite way; 4) In the process of germination, measurement of the electron transport rate and the fluorescence induction kinetics at room temperature showed that PSⅡ activities and efficiency of primary light energy transformation were only experimentally measurable after 7 days of germination and gradually increased afterwards. At the same time, the chl a/b ratio rose from the lower value to normal; 5) The changes of chloroplast membrane components and its functions are concomitant in concert with that of the ultrastructure of chloroplast membranes during germination, as shown in our earlier work . The results have proved again that a different developmental pathway of chloroplast is likely to exist in the lotus plumules, which might provide an important clue for N. nucifera in having an unique position in the phylogeny of the angiosperm.展开更多
A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell d...A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell divisions may be divided into three parts: proper, hypoblast and suspensor. The suspensor is short and small, and only exists transiently. As to the hypoblast there is a growth belt, which promotes elongation of the hypoblast. Eventually the upper portion of the hypoblast contributes to the formation of the coleorhiza and the remainder dries up, sticking to the end of the coleorhiza. 2. The maize embryo possesses dorsiventrality and cotyledon dimorphism. During early proembryo stage, the dorsiventrality appears in the proper of the embryo. On the ventral side, the cells are small with dense cytoplasm and few vacuoles. On the dorsal side, the cells are larger with lower cytoplasmic density and have more vacuoles. During later proembryo stage, the proper develops into two parts: the ventrum and the dorsurn. The ventrum rises up from the center of the ventral side. The dorsurn is composed of the marginal area of the ventral side and the whole dorsal side of the proper. During young embryo development, the ventrum differentiates into the coleoptile, apical meristem, hypocotyl, radicle and the main part of the coleorhiza. What is more important, the emergence of coleoptile primordium and radicular initials occur at the axis of the proper, then the coleoptile primordium expands from its two ends toward left and right to form a ring, and the endogenous radicular initials expand in all directions to form a conical radicular tip. All these morphogenetic activities of the ventrum follow a bilateral symmetrical pattern. The dorsurn forms the scutellum. primordium. Then the scutellum primordium, expands rapidly toward the left, right, front and back, while thickening itself, so as to make all components originating from the ventrum become hidden in the longitudinal groove of the scutellum. Lastly, the left and right lateral scales emerge from the edges of the longitudinal groove and expand toward the central line of the axis. As a consequence, morphologically, the bilateral symmetry of the ventral side of the embryo is revealed entirely. Morphogenetically, the coleoptile primordium and apical meristem in maize are similar to the coleoptile (apical cotyledon) and apex formation of the nice embryo, so the coleoptile of the maize embryo can also be considered as an apical cotyledon. The scutellum is a lateral cotyledon. These dimorphic cotyledons of the maize embryo originate from the dorsiventrality of the proper. 3. The true morphological structure of the maize embryo is recognized and its developmental stages are established. A maize embryo is a hypocotyl, in which the apical part is the shoot apex (or plumule) with the coleoptile, the central part consists mainly of the hypocotyl with a lateral cotyledon (scutellum), and the basal part is the radicle with coleorhiza. The left and right lateral scales derived from the scutellum overlap at the ventral side, leaving only two little pores at both ends of the seam from which the coleoptile and coleorhiza can be seen. The four sequential stages of maize embryonic development are as follows: (1) proembryo, stage. This stage covers a period from zygotic cell division to the appearance of the dorsum and ventrum. (2) ventrum rapid differentiation stage. (3) scutellum rapid expansion stage. (4) lateral scale development stage (or embryonic envelope formation stage). 4. To obtain a median longitudinal section perpendicular to the ventral surface is crucial for recognizing the genuine morphological structure of the maize embryo.展开更多
Seeds germination and seedling stages were studied on the legume seeds of Vicia angustifolia L. to reveal the effects of drought stress on germination char- acteristics and water absorption characteristics. The result...Seeds germination and seedling stages were studied on the legume seeds of Vicia angustifolia L. to reveal the effects of drought stress on germination char- acteristics and water absorption characteristics. The results showed that the rate of seed water uptake,germination percentage,germination index,vigor index,seedling height,root length and plant water content decreased with the increase of concen- tration of PEG stress. However,seedling and root dry weight and root/shoot ratio ini- tially increased followed by a decrease. The lowest osmotic potential threshold was -0.42 MPa.展开更多
A study was conducted to evaluate the effects of sludge （industrial and residential） on seed germination and growth performance of Acacia auriculiformis seedlings at the nursery of Institute of Forestry and Environm...A study was conducted to evaluate the effects of sludge （industrial and residential） on seed germination and growth performance of Acacia auriculiformis seedlings at the nursery of Institute of Forestry and Environmental Sciences, Chittagong University （IFESCU）, Bangladesh. Before sowing of the seeds, different combinations of sludge were incorporated with the nutrient-deficient natural forest soils. Seed germination and growth parameters of the seedlings （shoot and root length, collar diameter, fresh and dry weight of shoot, and root and total dry biomass） were recorded after one, two and three months of seed sowing. Physio-chemical parameters （pH, organic carbon, nitrogen, phosphorus, and potassium） and heavy metals （chromium, nickel, manganese, cadmium and zinc） of each treatment were also analyzed before sowing of seeds and after harvesting of seedlings. Results show that the seed germination percentage and the seedling growth parameters varied significantly in the soil added with sludge in comparison to control. The highest germination percentage （90%） was observed in the treatment of soil with residential sludge of 2：1 compared to control. The highest growth and biomass of the seedlings as well as the maximum percentage of organic carbon and nutrients （N, P and K） were also recorded in the same combination. Soil added with industrial sludge had a higher concentration of heavy metal than that of residential sludge. The highest concentrations of heavy metals were found in soil added with industrial sludge of 1：1. It is recommended that soil added with residential sludge of 2：1 provide good condition for better seed germination and growth ofA. auriculiformis seedlings in degraded forest soil.展开更多
A study was conducted to evaluate the effect of GA3, moist-chilling and temperature on seed germination ofAbies pindrow and Picea smithiana from five different provenances. Seeds were soaked in GA3 （10 mg·L^-1）...A study was conducted to evaluate the effect of GA3, moist-chilling and temperature on seed germination ofAbies pindrow and Picea smithiana from five different provenances. Seeds were soaked in GA3 （10 mg·L^-1） for 24 h, then chilled at 3-5℃ for 15 days. Four temperature regimes viz. 10℃, 15℃, 20℃ and 25℃ were used for stimulating seed germination. Results showed that soaking and chilling significantly increased germination percentage. The germination percentage was highest at 10℃. Overall results showed that soaking seeds in GA3 （10 mg·L^-1） for 24 h, moist chilling for 15 days, and germinating at 10℃ produced an effective germination in both the species studied. The statistical analysis of the data proclaimed significant effect of treatment, temperature, provenance and treatment with temperature interactions on seed germination.展开更多
An experiment was conducted to observe the inhibitory effects of the leaf extracts derived from Albizia lebbeck （L.） Benth. On germination and growth behavior of some popular agricultural crops （receptor） of Bangl...An experiment was conducted to observe the inhibitory effects of the leaf extracts derived from Albizia lebbeck （L.） Benth. On germination and growth behavior of some popular agricultural crops （receptor） of Bangladesh. Experiments were set on sterilized petridishes with a photoperiod of 24 h at room temperature of 27-30℃. The effects of the different concentrations of aqueous extracts were compared to distil water （control.）. The aqueous extracts of leaf caused significant inhibitory effect on germination, root and shoot elongation and development of lateral roots of receptor plants. Bioassays indicated that the inhibitory effect was proportional to the concentrations of the extracts and higher concentration （50%-100%） had the stronger inhibitory effect whereas the lower concentration （10%-25%） showed stimulatory effect in some cases. The study also revealed that, inhibitory effect was much pronounced in root and lateral root development rather than germination and shoot growth.展开更多
Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in med...Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in medium and the germination and growth of the seedlings is significant （P〈0.01）. The effect of Cu^2＋ to the germination, plant height, fresh weight, dried weight and the chlorophyll mount of the wheat seedling was stimulated under lower concentration of Cu^2＋ and was inhibited under higher concentration. With the increase of the Cu^2＋ concentration in the culture solution, the germination and growth of the seedlings was inhibited. The perfect positive correlation between the Cu^2＋ content in the plant and that in the culture solution was noted. Most of Cu^2＋ was concentrated in the root, and only a small amount was migrated to the aerial part of the wheat seedling. The sensitivity of each index to the Cu^2＋ concentration was ranked as follows： the Cu^2＋ content in the plant〉chlorophyll-a〉the ratio of chlorophyll-a to chlorophyll-b〉total chlorophyll〉plant height 〉germination〉fresh weight〉root elongation〉 chlorophyll-b 〉dried weight. The Cu^2＋ content in the wheat plant was the most sensitive index to the Cu^2＋ concentration in the culture solution.展开更多
To clarify the effect of exposure to methane fermentation on the survival of seeds of Rumexobtusifolius L. contained in dairy slurry, the percentage of seed germination was observed after the mesophilic （35 ℃） and ...To clarify the effect of exposure to methane fermentation on the survival of seeds of Rumexobtusifolius L. contained in dairy slurry, the percentage of seed germination was observed after the mesophilic （35 ℃） and thermophilic （55 ℃） methane fermentation. The number of survival seed was 0% at 55 ℃, 81.6% at 35 ℃ from methane fermentation, and 0% at 55℃, 75.5% at 35 ℃ after heat treatment. The survival rate of the seeds in methane fermentation was similar to heat treatment at 35 ℃. However, in the investigation of seed status, the number of primary and secondary dormant seeds was higher than after heat treatment. This result suggests that since Rumexobtusifolius L. seeds survive in dormant state in mesophilic methane fermentation, the usage of manure as fertilizer need to be considered.展开更多
Aims The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought.In the present study,we have compared the physio...Aims The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought.In the present study,we have compared the physiological responses to drought of two Retama raetam(retama)subspecies from Tunisia,one of them living under the desert climate(subsp.raetam)and the other one growing on the coast(subsp.bovei).Methods To physiologically characterize the two R.raetam subspecies,and to elucidate their main mechanisms underlying their tolerance to drought stress,parameters related to seed germination,growth,photosynthesis(net photosynthetic rate,intracellular CO_(2) concentration,transpiration rate,stomatal conductance and water-use efficiency)and accumulation of osmolytes(proline,glycine betaine[GB]and soluble sugars)were determined in 4-month-old plants subjected to stress for up to 1 month.Important Findings Drought significantly inhibited germination,growth and all the evaluated photosynthetic parameters.Plants of R.raetam subsp.bovei were severely affected by drought after 3 weeks of treatment when photosynthesis rates were up to 7-fold lower than in the controls.At the same time,proline and GB significantly accumulated compared with the irrigated controls,but much less than in R.raetam subsp.raetam;in the latter subspecies,proline and GB increased to levels 24-and 6-fold higher,respectively,than in the corresponding controls.In summary,the population living in the desert region exhibited stronger tolerance to drought stress than that adapted to the semiarid littoral climate,suggesting that tolerance in R.raetam is dependent on accumulation of osmolytes.展开更多
文摘The changes of chlorophyll_protein complexes and photosynthetic activities of chloroplast isolated from lotus ( Nelumbo nucifera Gaertn.) seeds germinating under illumination were studied. SDS PAGE analysis of chlorophyll_protein complexes showed that there was only the light harvesting chlorophyll a/b protein complex from PSⅡ (LHCⅡ) precursor in chloroplast from lotus seeds germinated for 2 to 6 days, while LHC Ⅱ 1, and the chlorophyll_protein complex of PSⅠ (CPⅠ) appeared on the 8th day of germination and PSⅡ reaction center complex appeared later. Studies on the polypeptides composition of the chloroplast revealed the following results: 1) Small amount of the 27 kD polypeptide was synthesized in invisible light; 2) The 30 kD polypeptide existed previously in the plumules of the dry seeds; 3) The amount of the 30 kD polypeptide was more than any other polypeptides before germination and decreased gradually throughout germination, while the 27 kD polypeptide changed in the opposite way; 4) In the process of germination, measurement of the electron transport rate and the fluorescence induction kinetics at room temperature showed that PSⅡ activities and efficiency of primary light energy transformation were only experimentally measurable after 7 days of germination and gradually increased afterwards. At the same time, the chl a/b ratio rose from the lower value to normal; 5) The changes of chloroplast membrane components and its functions are concomitant in concert with that of the ultrastructure of chloroplast membranes during germination, as shown in our earlier work . The results have proved again that a different developmental pathway of chloroplast is likely to exist in the lotus plumules, which might provide an important clue for N. nucifera in having an unique position in the phylogeny of the angiosperm.
文摘A series of new cognitions on the morphogenesis of maize ( Zea mays L.) embryo have been obtained with scanning electron microscopy and semi-thin section techniques. 1. The proembryo. The proembryo from zygotic cell divisions may be divided into three parts: proper, hypoblast and suspensor. The suspensor is short and small, and only exists transiently. As to the hypoblast there is a growth belt, which promotes elongation of the hypoblast. Eventually the upper portion of the hypoblast contributes to the formation of the coleorhiza and the remainder dries up, sticking to the end of the coleorhiza. 2. The maize embryo possesses dorsiventrality and cotyledon dimorphism. During early proembryo stage, the dorsiventrality appears in the proper of the embryo. On the ventral side, the cells are small with dense cytoplasm and few vacuoles. On the dorsal side, the cells are larger with lower cytoplasmic density and have more vacuoles. During later proembryo stage, the proper develops into two parts: the ventrum and the dorsurn. The ventrum rises up from the center of the ventral side. The dorsurn is composed of the marginal area of the ventral side and the whole dorsal side of the proper. During young embryo development, the ventrum differentiates into the coleoptile, apical meristem, hypocotyl, radicle and the main part of the coleorhiza. What is more important, the emergence of coleoptile primordium and radicular initials occur at the axis of the proper, then the coleoptile primordium expands from its two ends toward left and right to form a ring, and the endogenous radicular initials expand in all directions to form a conical radicular tip. All these morphogenetic activities of the ventrum follow a bilateral symmetrical pattern. The dorsurn forms the scutellum. primordium. Then the scutellum primordium, expands rapidly toward the left, right, front and back, while thickening itself, so as to make all components originating from the ventrum become hidden in the longitudinal groove of the scutellum. Lastly, the left and right lateral scales emerge from the edges of the longitudinal groove and expand toward the central line of the axis. As a consequence, morphologically, the bilateral symmetry of the ventral side of the embryo is revealed entirely. Morphogenetically, the coleoptile primordium and apical meristem in maize are similar to the coleoptile (apical cotyledon) and apex formation of the nice embryo, so the coleoptile of the maize embryo can also be considered as an apical cotyledon. The scutellum is a lateral cotyledon. These dimorphic cotyledons of the maize embryo originate from the dorsiventrality of the proper. 3. The true morphological structure of the maize embryo is recognized and its developmental stages are established. A maize embryo is a hypocotyl, in which the apical part is the shoot apex (or plumule) with the coleoptile, the central part consists mainly of the hypocotyl with a lateral cotyledon (scutellum), and the basal part is the radicle with coleorhiza. The left and right lateral scales derived from the scutellum overlap at the ventral side, leaving only two little pores at both ends of the seam from which the coleoptile and coleorhiza can be seen. The four sequential stages of maize embryonic development are as follows: (1) proembryo, stage. This stage covers a period from zygotic cell division to the appearance of the dorsum and ventrum. (2) ventrum rapid differentiation stage. (3) scutellum rapid expansion stage. (4) lateral scale development stage (or embryonic envelope formation stage). 4. To obtain a median longitudinal section perpendicular to the ventral surface is crucial for recognizing the genuine morphological structure of the maize embryo.
文摘Seeds germination and seedling stages were studied on the legume seeds of Vicia angustifolia L. to reveal the effects of drought stress on germination char- acteristics and water absorption characteristics. The results showed that the rate of seed water uptake,germination percentage,germination index,vigor index,seedling height,root length and plant water content decreased with the increase of concen- tration of PEG stress. However,seedling and root dry weight and root/shoot ratio ini- tially increased followed by a decrease. The lowest osmotic potential threshold was -0.42 MPa.
文摘A study was conducted to evaluate the effects of sludge （industrial and residential） on seed germination and growth performance of Acacia auriculiformis seedlings at the nursery of Institute of Forestry and Environmental Sciences, Chittagong University （IFESCU）, Bangladesh. Before sowing of the seeds, different combinations of sludge were incorporated with the nutrient-deficient natural forest soils. Seed germination and growth parameters of the seedlings （shoot and root length, collar diameter, fresh and dry weight of shoot, and root and total dry biomass） were recorded after one, two and three months of seed sowing. Physio-chemical parameters （pH, organic carbon, nitrogen, phosphorus, and potassium） and heavy metals （chromium, nickel, manganese, cadmium and zinc） of each treatment were also analyzed before sowing of seeds and after harvesting of seedlings. Results show that the seed germination percentage and the seedling growth parameters varied significantly in the soil added with sludge in comparison to control. The highest germination percentage （90%） was observed in the treatment of soil with residential sludge of 2：1 compared to control. The highest growth and biomass of the seedlings as well as the maximum percentage of organic carbon and nutrients （N, P and K） were also recorded in the same combination. Soil added with industrial sludge had a higher concentration of heavy metal than that of residential sludge. The highest concentrations of heavy metals were found in soil added with industrial sludge of 1：1. It is recommended that soil added with residential sludge of 2：1 provide good condition for better seed germination and growth ofA. auriculiformis seedlings in degraded forest soil.
文摘A study was conducted to evaluate the effect of GA3, moist-chilling and temperature on seed germination ofAbies pindrow and Picea smithiana from five different provenances. Seeds were soaked in GA3 （10 mg·L^-1） for 24 h, then chilled at 3-5℃ for 15 days. Four temperature regimes viz. 10℃, 15℃, 20℃ and 25℃ were used for stimulating seed germination. Results showed that soaking and chilling significantly increased germination percentage. The germination percentage was highest at 10℃. Overall results showed that soaking seeds in GA3 （10 mg·L^-1） for 24 h, moist chilling for 15 days, and germinating at 10℃ produced an effective germination in both the species studied. The statistical analysis of the data proclaimed significant effect of treatment, temperature, provenance and treatment with temperature interactions on seed germination.
文摘An experiment was conducted to observe the inhibitory effects of the leaf extracts derived from Albizia lebbeck （L.） Benth. On germination and growth behavior of some popular agricultural crops （receptor） of Bangladesh. Experiments were set on sterilized petridishes with a photoperiod of 24 h at room temperature of 27-30℃. The effects of the different concentrations of aqueous extracts were compared to distil water （control.）. The aqueous extracts of leaf caused significant inhibitory effect on germination, root and shoot elongation and development of lateral roots of receptor plants. Bioassays indicated that the inhibitory effect was proportional to the concentrations of the extracts and higher concentration （50%-100%） had the stronger inhibitory effect whereas the lower concentration （10%-25%） showed stimulatory effect in some cases. The study also revealed that, inhibitory effect was much pronounced in root and lateral root development rather than germination and shoot growth.
文摘Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in medium and the germination and growth of the seedlings is significant （P〈0.01）. The effect of Cu^2＋ to the germination, plant height, fresh weight, dried weight and the chlorophyll mount of the wheat seedling was stimulated under lower concentration of Cu^2＋ and was inhibited under higher concentration. With the increase of the Cu^2＋ concentration in the culture solution, the germination and growth of the seedlings was inhibited. The perfect positive correlation between the Cu^2＋ content in the plant and that in the culture solution was noted. Most of Cu^2＋ was concentrated in the root, and only a small amount was migrated to the aerial part of the wheat seedling. The sensitivity of each index to the Cu^2＋ concentration was ranked as follows： the Cu^2＋ content in the plant〉chlorophyll-a〉the ratio of chlorophyll-a to chlorophyll-b〉total chlorophyll〉plant height 〉germination〉fresh weight〉root elongation〉 chlorophyll-b 〉dried weight. The Cu^2＋ content in the wheat plant was the most sensitive index to the Cu^2＋ concentration in the culture solution.
文摘To clarify the effect of exposure to methane fermentation on the survival of seeds of Rumexobtusifolius L. contained in dairy slurry, the percentage of seed germination was observed after the mesophilic （35 ℃） and thermophilic （55 ℃） methane fermentation. The number of survival seed was 0% at 55 ℃, 81.6% at 35 ℃ from methane fermentation, and 0% at 55℃, 75.5% at 35 ℃ after heat treatment. The survival rate of the seeds in methane fermentation was similar to heat treatment at 35 ℃. However, in the investigation of seed status, the number of primary and secondary dormant seeds was higher than after heat treatment. This result suggests that since Rumexobtusifolius L. seeds survive in dormant state in mesophilic methane fermentation, the usage of manure as fertilizer need to be considered.
基金Dhikra Zayoud's stay in Valencia was supported by a grant from the Tunisian Ministry of Higher Education and Scientific Research.
文摘Aims The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought.In the present study,we have compared the physiological responses to drought of two Retama raetam(retama)subspecies from Tunisia,one of them living under the desert climate(subsp.raetam)and the other one growing on the coast(subsp.bovei).Methods To physiologically characterize the two R.raetam subspecies,and to elucidate their main mechanisms underlying their tolerance to drought stress,parameters related to seed germination,growth,photosynthesis(net photosynthetic rate,intracellular CO_(2) concentration,transpiration rate,stomatal conductance and water-use efficiency)and accumulation of osmolytes(proline,glycine betaine[GB]and soluble sugars)were determined in 4-month-old plants subjected to stress for up to 1 month.Important Findings Drought significantly inhibited germination,growth and all the evaluated photosynthetic parameters.Plants of R.raetam subsp.bovei were severely affected by drought after 3 weeks of treatment when photosynthesis rates were up to 7-fold lower than in the controls.At the same time,proline and GB significantly accumulated compared with the irrigated controls,but much less than in R.raetam subsp.raetam;in the latter subspecies,proline and GB increased to levels 24-and 6-fold higher,respectively,than in the corresponding controls.In summary,the population living in the desert region exhibited stronger tolerance to drought stress than that adapted to the semiarid littoral climate,suggesting that tolerance in R.raetam is dependent on accumulation of osmolytes.
