scholarly journals Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

2021 ◽  
Author(s):  
◽  
Sompop Intasuwan
Keyword(s):  
Genetic Variation ◽  
Exposure Time ◽  
Dry Weight ◽  
Pilot Scale ◽  
Gel Strength ◽  
Artificial Substrates ◽  
Agar Gel ◽  
Relative Growth ◽  
Daily Exposure ◽  
Plastic Bags

<p>The purpose of this study was to investigate the sporulation behaviour, the feasibility of farming in an open-water system, the quality and quantity of agar from a range of populations, and the genetic variation of the important agarophyte Gracilaria sordida W.A. Nelson (Gracilariales, Rhodophyta), which is widely distributed around New Zealand. The mean, total output of carpospores and tetraspores, and the periodicity of their release from G. sordida plants collected in the Wellington area, were measured under different levels of salinity, temperature, light intensity and daily exposure time to the air. The conditions that gave the greatest carpospore release were found to be approximately 15-35%. NaCl, l5-20' C, 50-200 uE.m-2 s-1 and 1-3 h daily exposure time. The conditions that gave the greatest tetraspore release were found to be approximately 15%. NaCl, l5-20' C, 150-200 uE.m-2 s-1 and 2-4 h daily exposure time. The diurnal periodicity of carpospore and tetraspore discharge based on hourly recordings was also measured. The peak rate of spore output occurred in the morning (7:00-8:00 hours) and in the late afternoon (16:00-17:00 hours). The carpospores and tetraspores not only had the same size but also showed the same germination pattern. A year-long pilot-scale farming project involving seeding the spores of sexually mature plants of G. sordida onto nets and ropes in Pauatahanui Inlet, Porirua Harbour, proved that this seaweed can be grown from spores on artificial substrates in field conditions. Of the artificial substrates tested, the best one for spore attachment was found to be polypropylene rope, and the relative growth rate on this substrate was maximal in spring (3.4%.d-1). The estimated production rate was 18.2 tonnes of dry weight per hectare per year. Problems encountered during field culture included epiphytes, sedimentation, storm damage and theft of floats and ropes. Yield and gel strength of agar extracts were studied from G. sordida collected in summer from 23 sites around the country. Native agar yield ranged from 17% to 32% (dry weight). The yield of native agar from cultured samples of these populations ranged from l0% to 29%. The yield of alkali-pretreated agar ranged from 9% to 24%. The gel strength of native agar ranged from 30 to 307 g.cm-2. Agar gel strength after alkali-pretreatment ranged from 230 to 625 g.cm-2. Native agar gel strength from cultured samples ranged from 177 to 342 g.cm-2. The gelling temperature of agar from wild populations ranged from 39 to 47' C for native agar and from 38 to 45' C for alkali-pretreated agar. The melting temperature of native agar ranged from 79 to 98' C. The melting temperature of alkali-pretreated agar ranged from 85 to 98' C. The maximum relative growth rate obtained from samples of G. sordida populations cultured in plastic bags was 6.2%.d-1, which was obtained from the Aramoana population. Starch gel electrophoresis of proteins was used to measure genetic variation in G. sordida. Protein extracts were prepared from 17 wild populations around New Zealand and from samples of these populations cultured in plastic bags. 20 isozyme loci were examined in G. sordida samples. Results indicated that G. sordida has low levels of genetic variation. Only two loci (Gd-1 and Pgm-1) of the 20 loci investigated were polymorphic (10%). Estimated heterozygosity of G. sordida was 0.011. There was no genetic variation between a native population and its cultured sample. The genetic distances between all populations were small. From the cluster analysis, all populations could be divided into two groups. Results indicated that populations were independent of each other, in which the effects of selection and genetic drift prevail. The buffer systems which gave the best protein resolution were Ridgeway (RW), Tris-EDTA-Borate (TEB) and Tris-Glycine (TG) and the enzyme which gave the best result in all buffer systems tested was Glucose-6-phosphate dehydrogenase (GD).</p>

scholarly journals Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

2021 ◽  
Author(s):  
◽  
Sompop Intasuwan
Keyword(s):  
Genetic Variation ◽  
Exposure Time ◽  
Dry Weight ◽  
Pilot Scale ◽  
Gel Strength ◽  
Artificial Substrates ◽  
Agar Gel ◽  
Relative Growth ◽  
Daily Exposure ◽  
Plastic Bags

<p>The purpose of this study was to investigate the sporulation behaviour, the feasibility of farming in an open-water system, the quality and quantity of agar from a range of populations, and the genetic variation of the important agarophyte Gracilaria sordida W.A. Nelson (Gracilariales, Rhodophyta), which is widely distributed around New Zealand. The mean, total output of carpospores and tetraspores, and the periodicity of their release from G. sordida plants collected in the Wellington area, were measured under different levels of salinity, temperature, light intensity and daily exposure time to the air. The conditions that gave the greatest carpospore release were found to be approximately 15-35%. NaCl, l5-20' C, 50-200 uE.m-2 s-1 and 1-3 h daily exposure time. The conditions that gave the greatest tetraspore release were found to be approximately 15%. NaCl, l5-20' C, 150-200 uE.m-2 s-1 and 2-4 h daily exposure time. The diurnal periodicity of carpospore and tetraspore discharge based on hourly recordings was also measured. The peak rate of spore output occurred in the morning (7:00-8:00 hours) and in the late afternoon (16:00-17:00 hours). The carpospores and tetraspores not only had the same size but also showed the same germination pattern. A year-long pilot-scale farming project involving seeding the spores of sexually mature plants of G. sordida onto nets and ropes in Pauatahanui Inlet, Porirua Harbour, proved that this seaweed can be grown from spores on artificial substrates in field conditions. Of the artificial substrates tested, the best one for spore attachment was found to be polypropylene rope, and the relative growth rate on this substrate was maximal in spring (3.4%.d-1). The estimated production rate was 18.2 tonnes of dry weight per hectare per year. Problems encountered during field culture included epiphytes, sedimentation, storm damage and theft of floats and ropes. Yield and gel strength of agar extracts were studied from G. sordida collected in summer from 23 sites around the country. Native agar yield ranged from 17% to 32% (dry weight). The yield of native agar from cultured samples of these populations ranged from l0% to 29%. The yield of alkali-pretreated agar ranged from 9% to 24%. The gel strength of native agar ranged from 30 to 307 g.cm-2. Agar gel strength after alkali-pretreatment ranged from 230 to 625 g.cm-2. Native agar gel strength from cultured samples ranged from 177 to 342 g.cm-2. The gelling temperature of agar from wild populations ranged from 39 to 47' C for native agar and from 38 to 45' C for alkali-pretreated agar. The melting temperature of native agar ranged from 79 to 98' C. The melting temperature of alkali-pretreated agar ranged from 85 to 98' C. The maximum relative growth rate obtained from samples of G. sordida populations cultured in plastic bags was 6.2%.d-1, which was obtained from the Aramoana population. Starch gel electrophoresis of proteins was used to measure genetic variation in G. sordida. Protein extracts were prepared from 17 wild populations around New Zealand and from samples of these populations cultured in plastic bags. 20 isozyme loci were examined in G. sordida samples. Results indicated that G. sordida has low levels of genetic variation. Only two loci (Gd-1 and Pgm-1) of the 20 loci investigated were polymorphic (10%). Estimated heterozygosity of G. sordida was 0.011. There was no genetic variation between a native population and its cultured sample. The genetic distances between all populations were small. From the cluster analysis, all populations could be divided into two groups. Results indicated that populations were independent of each other, in which the effects of selection and genetic drift prevail. The buffer systems which gave the best protein resolution were Ridgeway (RW), Tris-EDTA-Borate (TEB) and Tris-Glycine (TG) and the enzyme which gave the best result in all buffer systems tested was Glucose-6-phosphate dehydrogenase (GD).</p>

Genetic variation for rate of establishment in caucasian clover

1998 ◽  
pp. 213-217
Author(s):  
K.H. Widdup ◽  
T.L. Knight ◽  
C.J. Waters
Keyword(s):  
Genetic Variation ◽  
Root Growth ◽  
Seedling Growth ◽  
White Clover ◽  
Seedling Emergence ◽  
Red Clover ◽  
Dry Weight ◽  
Cool Season ◽  
Trifolium Ambiguum ◽  
Root Dry Weight

Slow establishment of caucasian clover (Trifolium ambiguum L.) is hindering the use of this legume in pasture mixtures. Improved genetic material is one strategy of correcting the problem. Newly harvested seed of hexaploid caucasian clover germplasm covering a range of origins, together with white and red clover and lucerne, were sown in 1 m rows in a Wakanui soil at Lincoln in November 1995. After 21 days, the caucasian clover material as a group had similar numbers of emerged seedlings as white clover and lucerne, but was inferior to red clover. There was wide variation among caucasian clover lines (48-70% seedling emergence), with the cool-season selection from cv. Monaro ranked the highest. Recurrent selection at low temperatures could be used to select material with improved rates of seedling emergence. Red clover and lucerne seedlings produced significantly greater shoot and root dry weight than caucasian and white clover seedlings. Initially, caucasian clover seedlings partitioned 1:1 shoot to root dry weight compared with 3:1 for white clover. After 2 months, caucasian clover seedlings had similar shoot growth but 3 times the root growth of white clover. Between 2 and 5 months, caucasian clover partitioned more to root and rhizome growth, resulting in a 0.3:1 shoot:root ratio compared with 2:1 for white clover. Both clover species had similar total dry weight after 5 months. Unhindered root/ rhizome devel-opment is very important to hasten the establishment phase of caucasian clover. The caucasian clover lines KZ3 and cool-season, both selections from Monaro, developed seedlings with greater shoot and root growth than cv. Monaro. KZ3 continued to produce greater root growth after 5 months, indicating the genetic potential for improvement in seedling growth rate. Different pasture estab-lishment techniques are proposed that take account of the seedling growth characteristics of caucasian clover. Keywords: establishment, genetic variation, growth, seedling emergence, Trifolium ambiguum

Growth, Nodulation and Nitrogen Fixation in Stylosanthes: Effect of Different Root Temperatures at two Shoot Temperatures

1989 ◽  
Vol 25 (4) ◽  
pp. 447-460 ◽  
Author(s):  
R. A. Date ◽  
D. Ratcliff
Keyword(s):  
Nitrogen Fixation ◽  
Dry Matter ◽  
Maximum Yield ◽  
Dry Weight ◽  
Strong Interactions ◽  
Root Temperature ◽  
Relative Growth ◽  
Stylosanthes Hamata ◽  
Nitrogen Yields ◽  
Controlled Environments

SUMMARYNodulated plants of Stylosanthes hamata, S. guianensis, S. humilis, S. scabra and S. fruticosa were grown in controlled environments with varied root and shoot temperatures. Measurement of dry matter and nitrogen content suggested that shoot temperature may be more important than root temperature in controlling growth and nitrogen fixation. There were strong interactions with variety. A fall in relative growth rate with increase in shoot temperature was least for S. guianensis and greatest for S. hamata and S. scabra. The optimum root temperature for growth and nitrogen fixation was approximately 30°C. Ninety percent maximum yield was achieved between root temperatures of 15–36°C for growth and 23–34°C for nitrogen fixation but varied with variety. Nitrogen fixation was more sensitive than dry weight to root temperature. The pattern of response of percentage nitrogen and nitrogen fixation efficiency reflected those for dry weight and nitrogen yields. Shoot to root ratios decreased toward the optimum root temperature then increased at the highest temperature. The reaction of varieties to root and shoot temperatures may be an important factor in determining their suitability for new regions.

scholarly journals Parasite variation and the evolution of virulence in a Daphnia-microparasite system

Parasitology ◽  
2007 ◽  
Vol 135 (3) ◽  
pp. 303-308 ◽  
Author(s):  
T. J. LITTLE ◽  
W. CHADWICK ◽  
K. WATT
Keyword(s):  
Genetic Variation ◽  
Rank Order ◽  
Genetic Relationships ◽  
Natural Populations ◽  
Host Genotype ◽  
Relative Growth ◽  
Trade Off ◽  
Relative Growth Rates ◽  
Pasteuria Ramosa ◽  
Evolution Of Virulence

SUMMARYUnderstanding genetic relationships amongst the life-history traits of parasites is crucial for testing hypotheses on the evolution of virulence. This study therefore examined variation between parasite isolates (the bacterium Pasteuria ramosa) from the crustacean Daphnia magna. From a single wild-caught infected host we obtained 2 P. ramosa isolates that differed substantially in the mortality they caused. Surprisingly, the isolate causing higher early mortality was, on average, less successful at establishing infections and had a slower growth rate within hosts. The observation that within-host replication rate was negatively correlated with mortality could violate a central assumption of the trade-off hypothesis for the evolution of virulence, but we discuss a number of caveats which caution against premature rejection of the trade-off hypothesis. We sought to test if the characteristics of these parasite isolates were constant across host genotypes in a second experiment that included 2 Daphnia host clones. The relative growth rates of the two parasite isolates did indeed depend on the host genotype (although the rank order did not change). We suggest that testing evolutionary hypotheses for virulence may require substantial sampling of both host and parasite genetic variation, and discuss how selection for virulence may change with the epidemiological state of natural populations and how this can promote genetic variation for virulence.

scholarly journals Effects of partial defoliation on the growth, ion relations and photosynthesis of Lycium chinense Mill. under salt stress

2015 ◽  
Vol 67 (4) ◽  
pp. 1185-1194 ◽  
Author(s):  
Yuan Guo ◽  
Qiong Yu ◽  
Xiaohui Feng ◽  
Zhixia Xie ◽  
Xiaojing Liu
Keyword(s):  
Salt Stress ◽  
Physiological Response ◽  
Electron Transport Rate ◽  
Dry Weight ◽  
Photochemical Quenching ◽  
Leaf Water Content ◽  
Lycium Chinense ◽  
Fresh Weight ◽  
Relative Growth ◽  
Ion Relations

In this study, we investigated the effects of artificial defoliation on the growth and physiological response of Lycium chinense Mill. to salt stress. Our results show that partial defoliation increases the plant relative growth rate, leaf water content and dry weight-based leaf Na+ content, and reduces the fresh weight-based leaf Na+ content under salt stress. In response to defoliation, the leaf Na+/Ca2+ and Na+/Mg2+ ratios were decreased, but the K+ content remained unchanged. The contents of ROS and MDA were decreased in defoliated plants. Net The photosynthetic rate (PN), stomatal conductance (gs), electron transport rate (ETR), actual photochemical quenching (?PSII) and photochemical quenching (qp) were enhanced by defoliation. Together, these findings indicate that partial defoliation mitigates the salt-induced growth inhibition and physiological damage in L. chinense.

scholarly journals Electromagnetic Fields (0.04 to 0.39) mT effect on cellular growth cycles of Saccharomyces cerevisiae wine strains

2019 ◽  
Vol 17 (2) ◽  
pp. 196
Author(s):  
Eliseo Amado-González ◽  
Alveiro Álvarez Ovallos ◽  
Alfonso Quijano Parra
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Electromagnetic Fields ◽  
Biomass Production ◽  
Exposure Time ◽  
Culture Media ◽  
Dry Weight ◽  
Cellular Growth ◽  
Biomass Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
Growth Cycles

Low frecuency electromagnetic fields effect (EMF) on growth cycles of yeast Saccharomyces cerevisiae wine strains Rv1 and Rhône were studied.  A cylindrical coil induced magnetic fields with inductions up to 0,39 mT. Exposure time to EMF varied between (1 – 10) min at 30 °C.  The biomass growth were monitored in the reactor culture media (yeast extract + by measurement optical density from (0 to 32) h. The biomass was found by dry weight. After yeast expose to the different EMF, the number of growth cycles decreased from 4 cycles to 2 or 1. However, the biomass production increased almost 50 %.  The best biomass production was found at 0.39 mT and 10 min exposure time.  Keywords: Electromagnetic fields, Saccharomyces cerevisiae, biomass production, RV1

scholarly journals Influence of Soil Amendment on the Relative Growth Rate and Net Assimilation Rate of Phaseolus vulgaris and Vigna aconitifolia

2020 ◽  
pp. 1-13
Author(s):  
E. A. Effa ◽  
A. A. J. Mofunanya ◽  
B. A. Ngele
Keyword(s):  
Growth Rate ◽  
Phaseolus Vulgaris ◽  
Relative Growth Rate ◽  
Soil Amendment ◽  
Dry Weight ◽  
Organic Manure ◽  
Assimilation Rate ◽  
Vigna Aconitifolia ◽  
Relative Growth ◽  
Net Assimilation

Background: Soil pH is one of the most important factors that contribute to crop growth and productivity. The present research was designed to assess the influence of soil amendment using organic manure and agricultural lime on the relative growth rate (RGR) and net assimilation rate (NAR) of Phaseolus vulgaris and Vigna aconitifolia grown on soils from different locations. Methodology: The three locations were: Akamkpa, Calabar Municipality and Odukpani. The pH for the three soil locations were 4.0, 7.0 and 9.0, respectively. The treatments were; control (0 g), OM1 (100 g organic manure), OM2 (200 g organic manure), AL1 (100 g agricultural lime), AL2 (200 g agricultural lime), OM1 + AL1 (50 g organic manure + 50 g agricultural lime) and OM2 +AL2 (100 g organic manure and 100 g agricultural lime). Results: Results obtained on the RGR of the leaf dry weight of P. vulgaris treated with OM2 was the highest (0.50 g/wk) followed by OM1 (0.41 g/wk). OM1 + AL1 had the highest RGR of the stem dry weight of P. vulgaris grown on soil from Calabar Municipality. In the RGR of the root dry weight, OM2 had the highest mean value in both plants grown on Akamkpa soil. Results obtained at 4 weeks after planting (WAP) revealed that there was significant (P<0.05) increase in NAR of plants grown on soil from Akamkpa. The highest NAR was obtained for V. aconitifolia treated with OM2 (0.0447 g/wk) followed by OM2 + AL2 (0.0057 g/wk) for both V. aconitifolia and P. vulgaris. P. vulgaris grown on Akamkpa and Odukpani soils treated with AL2 (0.0032 g/wk), OM1 + AL1 (0.0041 g/wk) and OM2+ AL2 (0.0062 g/wk) had the highest NAR at 8 WAP. Conclusion: The RGR and NAR of the two bean varieties were improved following treatments with organic manure and agricultural lime.

The effect of barley yellow dwarf virus on early plant growth in ryegrass (Lolium spp.)

1989 ◽  
Vol 40 (2) ◽  
pp. 293 ◽  
Author(s):  
DR Eagling ◽  
RJ Sward ◽  
GM Halloran
Keyword(s):  
Leaf Area ◽  
Growth Rates ◽  
Barley Yellow Dwarf Virus ◽  
Dry Weight ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Root Dry Weight ◽  
Shoot Dry Weight ◽  
Barley Yellow Dwarf ◽  
Yellow Dwarf Virus

Measurements were made on the effect of barley yellow dwarf virus (BYDV) infection on the early growth of four commercial cultivars of ryegrass (Lolium spp.) under two different temperatures (24�C and 16�C). At 24'C, BYDV infection was associated with reduced root dry weight (30-40%) in all cultivars; the effect of infection on shoot dry weight and leaf area was variable. At 16�C, the effect of BYDV infection was variable, being associated with increases in root dry weight, shoot dry weight, and leaf area in one cultivar (Grasslands Ariki) and decreases in another (Victorian). In two other cultivars, root dry weight, shoot dry weight and leaf area were not significantly affected (P>0.05) by infection with BYDV.At 24�C, the reductions in root dry weight associated with BYDV infection were not concomitant with reductions in the root relative growth rates. Up to at least 28 days after inoculation (46-50 days after germination) reductions in root dry weight were associated with both aphid-feeding damage and virus infection. Experiments with the cultivar Victorian, showed that shoot dry weight was not significantly affected (P>0.05) by feeding with viruliferous (BYDV) or non-viruliferous aphids (Rhopalosiphum padi L.). At 16�C, changes in root and shoot dry weight were associated with changes in the root and shoot relative growth rates.

A study of growth in swards of timothy and meadow fescue. I. Uninterrupted growth

1958 ◽  
Vol 51 (3) ◽  
pp. 347-352 ◽  
Author(s):  
R. H. M. Langer
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Leaf Size ◽  
Dry Weight ◽  
Meadow Fescue ◽  
Area Index ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Number Of Leaves ◽  
Total Dry Weight

1. Swards of S. 48 timothy and S. 215 meadow fescue growing alone or together were sampled at intervals of 3 weeks throughout the season. The number and weight of leaves, stems and ears were determined, and leaf area was estimated.2. Despite high rainfall, the total number of tillers in both species declined from the beginning of the experiment until early July, but increased again from then onwards until the original complement had been approximately restored. The number of leaves failed to show a corresponding increase in the autumn because each tiller carried fewer leaves than earlier in the year.3. In the spring total dry weight increased more rapidly in meadow fescue than in timothy which in turn out-yielded meadow fescue later in the season. Both species attained their greatest dry weight soon after ear emergence, a period which was marked by considerable crop growth and relative growth rates.4. Leaf area index reached a maximum before total dry weight had increased to its highest level, but then declined in both species. Meadow fescue differed from timothy by producing a second crop of foliage after the summer with a leaf area index of about 7. This second rise appeared to be due mainly to increased leaf size in contrast to timothy whose leaves became progressively smaller towards the end of the season.5. The differences in growth between the species discussed with reference to their dates of ear emergence which in this experiment differed by about 6 weeks.

Seedling growth of summer-dormant and non-dormant ryegrasses in relation to temperature

1969 ◽  
Vol 20 (3) ◽  
pp. 417 ◽  
Author(s):  
JH Silsbury
Keyword(s):  
Dry Matter ◽  
Growth Curves ◽  
Dry Weight ◽  
Detailed Examination ◽  
Dry Matter Production ◽  
Controlled Environment ◽  
Lolium Rigidum ◽  
Relative Growth ◽  
Lolium Perenne L ◽  
Matter Production

Lolium rigidum Gaud. and a summer-dormant and a non-dormant form of Lolium perenne L. were grown as seedling plants for 32 days in controlled environment cabinets at constant temperatures of either 10, 20, or 30°C and in all cases with a 16-hr photoperiod at a light intensity of 3600 lm ft-2. Sampling at 4-day intervals permitted the detailed examination of dry matter growth curves. Differences in total dry matter production were related to initial differences in seedling dry weight, and the general responses to temperature were similar for each ryegrass. Total dry matter production was greatest at 20°C and lowest at 10°. A temperature of 30° did not induce dormancy in the summer-dormant ryegrass but did depress growth. Relative growth rate fell with time at each temperature.

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