Normal Seedlings Research Articles

Mudanças no potencial fisiológico de sementes de crotalária durante o armazenamento

ABSTRACT Sunn hemp (Crotalaria spectabilis) is widely used for soil correction and cover, but it is still necessary to know the characteristics that influence the storage of its seeds. This study aimed to evaluate the physiological quality of sunn hemp seeds under uncontrolled environmental conditions and in acclimatization chamber. A completely randomized experimental design was used, with four replicates, in subplots evaluated in different periods. Freshly harvested seeds and seeds at 90, 180 and 270 days of storage were evaluated for germination, first germination count, germination speed index, seedling emergence in the field, accelerated aging, cold test and seedling growth. The environment and storage time significantly influenced the seed germination and vigor. The seeds showed a high physiological performance for both the environmental conditions, maintaining the ability to produce normal seedlings up to approximately 150 days of storage, deteriorating afterwards, although without losing their germination capacity up to 270 days of storage.

Seed Vigour Tests on seven Cultivars of Phaseolus vulgaris Grown in Chamoli District of Uttarakhand, India

Rajmash (Phaseolus vulgaris L. family; fabaceae) is also known as kidney bean/ French bean. It is an annual plant and cultivated throughout the world for their edible beans. The present study was conducted to investigate the effect of seed vigour by germination test of different cultivars of Phaseolus vulgaris grown in Chamoli district of Uttarakhand. The experimental material constituted a collection of 7 cultivars (Red small, Red big, Grey, Pink, Yellow, Brown, White) of Phaseolus vulgaris. The seed samples of seven cultivars of Phaseolus vulgaris were taken from Joshimath, District Chamoli Garhwal Uttarakhand. Morphological aspects viz; seed weight, seed moisture content, seed density and seed diameter were recorded prior to germination test of Phaseolus vulgaris at Seed Testing Laboratory, Department of Seed Science and Technology, H.N.B Garhwal University. Seeds were sterilized with 0.2% sodium hypochlorite solution for germination test. Two replicates of each variety and 25 seeds in each replicates were kept in petriplates on whatman filter paper. Petriplates were kept in seed germinator at 25 ± 2 °C until final count. The number of normal seedling was counted at the final count, higher the number of normal seedlings greater is the seed vigour. The germination percentage was found 100% in five cultivars, and the other two cultivars showed 96.66% in yellow seeds and 68.33% in Grey cultivar of Phaseolus vulgaris. Brown cultivars represented maximum dry weight of root (0.029 g) while minimum dry weight of root has been recorded in yellow cultivar (0.01353 g). Maximum vigour index were recorded in brown cultivar and minimum was recorded in pink cultivar. The findings from the study indicate that brown cultivar of Phaseolus vulgaris is highly vigours.

Conservation and physiological quality of Handroanthus spongiosus (Rizzini) S. Grose (Bignoniaceae) seeds

Abstract: Handroanthus spongiosus (Rizzini) S. Grose is an endangered tree species. However, its seed quality, storage, and conservation strategies are issues still unexplored. This study aimed to evaluate the physiological quality of H. spongiosus seeds subjected to different storage times, packaging, and environments for their conservation. A completely randomized experimental design was used, in a double factorial arrangement with an additional treatment (recently-harvested seeds), consisted of five storage times (up to 24 months) and six storage conditions, combining packaging types (permeable and impermeable) and environments (room, cold chamber, freezer, and liquid nitrogen conditions). Seed germination percentage and normal seedling percentage, shoot length, root length, and root to shoot dry weight ratio were evaluated. The seed germination and normal seedling percentages of H. spongiosus seeds conserved under room conditions decreased over the storage time. Normal seedling percentages decreased from the 12th month of storage onwards. Low and ultralow temperatures are recommended for short and medium-term conservation of H. spongiosus seeds, since they did not affect the growth of seedlings.

Scarification and doses of Acadian®, Stimulate® and Trichoderma spp. promote dormancy overcoming in Hymenaea courbaril L. seeds?

Abstract: The present study establishes the following research problem: Can different concentrations of Acadian®, Stimulate®, and Trichoderma spp. be effective in promoting the emergence and vigor of Hymenaea courbaril seedlings with or without mechanical scarification? The experimental design used was completely randomized, in a 4 x 3 x 2 factorial scheme, corresponding to four concentrations (0, 5.0, 10.0, and 15.0 mL.L-1), three hormones (Acadian®, Stimulate® and Trichoderma spp.), with and without mechanical scarification, with four replicates, each of which consisting of 25 seeds. Acadian® at a concentration of 5.0 mL.L-1 in scarified seeds of H. courbaril leads to a greater increase in the percentage of emergence and percentage of normal seedlings. Stimulate® at concentrations of 10.0 and 15.0 mL.L-1 is efficient in obtaining more than 85% emergence seedlings with seeds subjected to mechanical scarification. Trichoderma spp. from 9.0 mL.L-1 does not favor gains in the percentage of normal seedlings of Hymenaea courbaril grown from seeds with and without mechanical scarification. The dose of maximum technical efficiency (DMTE) of the bioregulator Acadian® is 8.50 mL.L-1 and, in scarified seeds of H. courbaril, it increases the percentage of seedling emergence.

Early counts of radicle emergence, counted manually and by image analysis, can reveal differences in the production of normal seedlings and the vigour of seed lots of cauliflower

The ability of a single early count of radicle emergence (RE) to predict differences in the production of normal seedlings (NG) and seed vigour was examined in four seed lots from each of three varieties of cauliflower (Brassica oleracea var botrytis). Initial seed quality was assessed in germination and controlled deterioration (CD) vigour tests. RE (first appearance of the radicle) was counted manually after 48 hours in the germination test (RE 48h 20/30°C) and every two hours for 144 hours at 20°C using automated image analysis. Seed vigour was assessed in field and glasshouse trials. A large proportion of the variance in NG was explained by the RE count. The same RE counts at 20/30°C and 20°C predicted seed vigour in the field and glasshouse and revealed the same vigour differences as the validated CD test. Differences in vigour (field and glasshouse emergence) observed between varieties were related to the extent of previously sustained seed ageing revealed by the CD test, although genotypic differences in vigour could not be excluded. We propose that single counts of RE taken manually or by image analysis can be used to reveal differences in the NG and vigour of seed lots of cauliflower.

Germination and vigour of seed of sorghum (Sorghum bicolor L. Moench) treated with Arsenicum album

Rosimar Maria Marques1; Bruno Reis1; Anielen C. Tormena Cavazin1; Flávia Carolina Moreira1; Monica G. Buchoski1; Hingrid Ariane Silva1; Mayara A. Lois1; Carlos Moacir Bonato1*
 
 1Universidade Estadual de Maringá – UEM
 
 1* Orientador – cmbonato@uem.br
 
 Introduction: The accelerated aging test evaluates the behavior of seeds exposed to stress conditions based on the fact that the rate of deterioration is considerably increased by exposure to high temperature and relative humidity [1]. The knowledge acquired in homeopathic science is experimental research on healthy living organisms that are undergoing experimentation using homeopathic medicines [2]. The experimental research on homeopathic plants has been performed in Europe, Mexico, India and Brazil, proving that the principle of homeopathy, as set out in the animal kingdom has been found in plants [3]. This experiment aimed to evaluate the effect of the homeopathic Arsenicum album in decimal (x) and centesimal (cH) scale on the physiological variables of the germination and growth of sorghum (Sorghum bicolor L.) subjected to accelerated aging.
 
 Materials and methods: The experiment was conducted at the Laboratory of Plant Physiology and Homeopathy, Universidade Estadual de Maringá - UEM. Arsenicum album 6x and 2CH matrices were acquired in homeopathic pharmacy. From matrices were prepared further dynamizations in decimal (x) and centesimal (C) scale, according to the Brazilian Homeopathic Pharmacopoeia [4]. In the accelerated aging test were used samples of 200 seeds per treatment distributed evenly forming a single layer on the surfaces of metal wire suspended inside the plastic box containing inside 40ml of Arsenicum album (9, 12, 18, or 30x 24 and 9, 12, 18, 24 or 30C). The control consisted of distilled water. The boxes were placed in BOD-chamber adjusted to 42°C and relative humidity 100% for 96 hours. After this period, led to the germination test, using four replicates of 50 seeds, totalizing 52 experimental units which were placed on germination paper previously soaked with distilled water in an amount equivalent to 2.5 times the paper weight[5]. The rolls were arranged randomly in the BOD-chamber at 25°C±2. The interpretation of the test was performed after seven days [6]. Germination percentage (% PG) was determined according to the Rules for Seed Analysis [5]. The length of primary roots (PRL) and hypocotyl (LH) were only performed in normal seedlings. The total length of the radicle (TLR) was calculated as the sum of the lengths of hypocotyl and primary root. The experimental design was completely randomized. We adopted the double-blind procedure, avoiding possible interference from the researcher. Data were subjected to analysis of variance and means compared by Scott-Knott test (P ≤ 0.05).
 
 Results: Arsenicum album 9x, 9CH and 12CH reduced the percentage of germination (%PG) (Figure 1A). The highest values in the length of hypocotyl (LH) ​​were observed in 12 and 24x dilutions, followed by a reduction in intermediate and higher inhibition at 30x and 9x. The 18x does not differ from control. All centesimal dilution presented effect on the variable analyzed. There was an increase in hypocotyl length in the 12, 18 and 24 dilutions, and reduction in 9 and 30 cH dilutions (Figure 1B). The primary root length (PRL) of sorghum was increased in dilutions 18 and 30x. However, the centesimal dilutions were not different from control (Figure 1C). There was an increase in the total length of the seedlings (TLS) in the dilutions 18, 24 and 30x and reduction in 9x when compared to control. As for centesimal dilutions, there was an effect only in 18cH. The other centesimal dilutions were not different from control (Figure 1D).
 
 Conclusions: In general, homeopathic preparations did not affect the germination percentage except for 9x, and 9cH 12cH dilution. Furthermore, the dilutions reduced the effects on premature aging verified by high values ​​of growth variables. These results suggest that high dilution Arsenicum album can be an alternative to minimize the deleterious effect to high temperature.

BREAKING SEED DORMANCY IN Sesbania punicea (Cav.) Benth

The objective of this study was to evaluate methods of breaking dormancy in Sesbania punicea seeds for seedling production. The treatments used were control, manual scarification for 40 s, manual scarification for 60 s, thermal scarification and chemical scarification. After the treatments were carried out, the seeds were placed to germinate at 25 ºC and a 16-hour photoperiod for 14 days. The germination percentage, average germination time, germination speed index, percentage of normal seedling formation, shoot length, root system length and percentage of hard seeds were evaluated. A completely randomized design with four replications of 25 seeds was used. The data were submitted to ANOVA and the means compared by Tukey 5%. There was a difference for all the analyzes evaluated, except for the length of the aerial part. The treatment with manual scarification 60 s had superior results, being indicated for overcoming dormancy of seeds of S. punicea.

Diversity of the Seed Material of Selected Plant Species of Naturally Valuable Grassland Habitats in Terms of the Prognosis of Introduction Success

The current conservation status of semi-natural grassland habitats in Poland indicates that actions for their restoration are necessary. Many of the degraded sites require the introduction of diaspores of representative species because other methods of improving their condition are not sufficiently effective. Meanwhile, little is known about the diaspores of native wild-flower species and the biology of their seeds. The aim of the present study was to find an answer to the question of which features of the seed material can guarantee the success of the introduction. The study covered 28 plant species of 4 non-forest natural habitats (codes: 6440, 6410, 6510, 6210) occurring in river valleys. Diaspores were collected in 2015–2017. Morphometric measurements of diaspores were performed, the weight of 1000 diaspores was determined and the germination capacity analysis was carried out in accordance with ISTA Rules. The analysis was made with the division into normal seedlings, abnormal seedlings, dead seeds and fresh ungerminated seeds. Species with similar parameters of seed material were selected using the method of hierarchical clustering and PCA analysis. Three groups of species were distinguished: (1) with good seed germination capacity (above 65%), which, regardless of weather conditions during the generative development, and despite the small size of diaspores, can guarantee successful introductions (Verbascum thapsus, Veronica longifolia, Daucus carota, Plantago lanceolata); (2) species of little suitability for introduction, due to the large proportion (over 50%) of dead seeds (Armeria maritima, Linaria vulgaris, Potentilla erecta, Centaurea stoebe, Sanguisorba officinalis, Cnidium dubium); (3) species with relatively large size of diaspores and low seed germination capacity, due to the high proportion of fresh ungerminated seeds which means dormant seeds (Lathyrus pratensis, Geranium pratense).

Allelopathic activity of Piptadenia moniliformis Benth. on the physiological potential of seeds of Amburana cearensis Allem.

The adoption of agroforestry systems or reforestation programs contributes to the economy of a region in a sustainable way, since the adopted species can be exploited by the cosmeceutical and pharmaceutical industries. For the establishment of plant species in a given area, studies are needed on the interaction that can develop between them, with emphasis on research on allelopathy. Given the above, the aim of this study was to evaluate the allelopathic effect of the aqueous extract of leaves of the native species Piptadenia moniliformis on the initial development of the forest species Amburana cearensis. The aqueous extract was used at different concentrations. (0 - water, 25, 50, 75 and 100%), adopting a completely randomized design. The following characteristics were evaluated: emergence percentage, emergence speed index, mean emergence time, shoot and root length and total shoot, root and total dry part of normal seedlings. The 100% concentration of the aqueous extract of P. moniliformis leaves reduced the emergence percentage of A. cearensis seedlings. A smaller number of normal seedlings was observed at concentrations of 75 and 100%. The initial development of seedlings was hampered by the increase in extract concentrations. The aqueous extract of fresh leaves of P. moniliformis provides a negative allelopathic effect for both emergence and early development of A. cearensis seedlings, therefore intercropped cultivation among the forest species is not recommended.

A novel non-antibiotic selectable marker GASA6 for plant transformation

Selectable markers help the transformed cell/tissue to survive in an otherwise lethal exposure to an antibiotic or herbicide. Unfortunately, almost all the traditional selectable markers are antibiotic and herbicide resistance genes, which are controversial on human health concerns and environmental impact. Novel plant-derived, non-antibiotic, and non-herbicide selectable markers are urgently needed in plant transformation. Our previous work showed that the seedlings of overexpression Arabidopsis lines of AtGASA6 survived on medium with a high concentration of sugar, which leads to the hypothesis that AtGASA6 could be a selectable marker on media with high or low sugar content. In this study, leaf explants of AtGASA6 overexpression tobacco lines regenerated shoots on sugar-free shooting medium while those of wild type could not. Moreover, the seeds of AtGASA6 overexpression tobacco lines germinated and grew into normal seedlings on sugar-free MS medium while those of WT could not. Attractively, no developmental defects were observed in AtGASA6 transgenic progenies. Using AtGASA6 as a selectable marker, overexpression tobacco lines of GAI, which restrains plant size, were created on sugar-free media. The GAI overexpression lines had a smaller plant size than that of control. Considering its plant-derived and non-antibiotic nature, GASA6 is promising to be used as a selectable marker in plant transformation.

Unrevealing the impact of pulsed electric fields (PEF) on cucumber seed vigour and surface disinfection

Abstract Chemicals used for seed treatments help to increase the agricultural production by preventing pests and pathogens but also cause environmental and health problems. Thus, environmentally-friendly technologies need to be developed for a seed treatment that inactivates surface microflora and improves seed vigor. One such pulsed electric field (PEF) treatment applied to cucumber seeds in the range of 1.07-17.28 Joule (J) significantly enhanced a mean germination rate (MGR) by up to 9%, a normal seedling rate by 25.73%, and a resistance to 100 and 200 mM salt stresses by 96% and 91.67%, respectively, with a stronger and faster growth of roots and seedlings. PEF treatment provided 3.34 and 3.22 log-reductions in the surface microflora of total mold and yeast and total aerobic mesophilic bacteria, respectively. The electrical conductivity (EC) values of the control samples increased over time, from 4 to 24 h. Those of the PEF-treated samples after 4, 12, and 24th hours were also more affected by the measurement time not by the PEF treatment. The joint optimization of 18 responses based on the best-fit Gaussian process model pointed to 19.78 s and 17.28 J as the optimal settings. The PEF treatment appeared to improve seed germination ability and stress resistance with the adequate inactivation of surface microflora.

Alternative methodology for the germination test in chemically treated corn hybrid seeds

The objective of this work was to identify the most suitable conditions for the evaluation of the germination test in corn seeds through the use of different substrates. Two tests were carried out for the development of the work. In test 1, the hybrid Morgan 30A37 PWV was used in a factorial scheme of 5 substrates with 8 chemical treatments. The seeds were treated industrially with the following insecticides: Inside FS, Inside FS + Maestro FS, Maestro FS, Poncho, Inside FS + BioCoat Corn, Inside FS + Maestro FS + BioCoat Corn and Maestro FS + BioCoat Corn. For test 2, the hybrid used was the FS533 PWV in a factorial scheme of 5 substrates and 5 treatments, in which the seeds received the industrial treatment with the insecticides: Inside FS, Inside FS + Maestro FS, Maestro FS and Poncho. Both tests were submitted to two temperatures (20°C and 25°C) and five substrates (germitest® paper; germitest® paper + sand; germitest® paper + soil; germitest® paper + coal and brown paper). The most suitable substrates for installing the germination test in chemically treated corn seeds were brown pepper and germitest® + charcoal. And the temperature of 20°C is the one that allows the most uniform and rapid development of normal seedlings in the germination test in treated hybrid corn seeds.

Cold test on the vigor determination of Carthamus tinctorius L. seeds

In evaluating the quality of seed lots, vigor tests are complementary to the germination test, identifying differences in their degree of deterioration. However, for safflower seeds (Carthamus tinctorius L.) there is little information regarding these tests. Thus, the objective was to adapt the cold test methodology to evaluate the vigor of safflower seeds. For that, twelve lots were initially characterized by moisture content, mass of one thousand seeds, germination and seedling emergence in the field. After characterization the samples were conditioned in transparent plastic boxes on paper moistened with water and kept at 10 °C for the periods of 0, 3, 5 and 7 days. After the conditioning periods the samples were transferred to a germination chamber at 25 ºC, with evaluation of normal seedlings on the 3rd day. The obtained data was subjected to variation analysis and when significant, compared by the Scott-Knott method at 5% probability. To verify the efficiency of the methodologies, the principal component analysis was performed. The cold testing at 10 °C for 7 days is recommended for evaluating the physiological quality of safflower seeds.

Pengaruh Priming pada Vigor Benih Kedelai (Glycine max. [L] Merrill) yang Dikecambahkan pada Tanah Masam

The need of soybeans continuously increases due to the increasing of human population. The germination of soybeans seeds in the acid soil such as ultisol soil often experienced barrier. One of the ways to improve seed germination in the acid soils is to give priming treatment on the seeds. The research was conducted in the green house of the Integrated Field Laboratory, Faculty of Agriculture, the University of Lampung. It was conducted from December 2020 to March 2021. The research used factorial treatment that was applied in the Completely Random Design with three replicates. The Tukey’s Honestly Significance Difference with 5% level of significance was used to compare the average of treaments. Data analyzing was done by using R studio statistics program. The first factor was kinds of priming which consisted of without priming as a controle, water priming within 12 hours, KNO3 1% within 3 hours, KNO3 2% within 6 hours, GA3 50 ppm within 14 hours, GA3 100 ppm within 14 hours, and PEG 7,5% within 24 hours. The second factor was three soybean seed varieties, i.e. Anjasmoro, Burangrang, and Grobogan. Results showed that Giberelin priming of 50 ppm for 14 hours was the best priming in seedling emergence in the ultisol soils. The Burangrang soybean seeds showed the best T50% and the number of radicles appeared in the first day. The Anjasmoro soybean seeds showed the best response in the dry weight of normal seedling and hypocotyls lenght of normal seedling in the ultisol soils.Key Words: Priming, soybean, ultisol, variety

Viability of Mimosa caesalpiniifolia Benth. seeds as a function of fruit maturity stage and storage temperature

The maintenance of seed viability during storage is influenced by several factors related to the species and to the environment. This work aimed to determine the viability of Mimosa caesalpiniifolia seeds from unripe and ripe fruits stored at different temperatures (ambient, 10 oC, 0 oC and -21 oC). For this, the germination performance of the seeds was evaluated at 0, 3, 6 and 12 months of storage. The experimental design was completely randomized, with four replicates of 25 seeds per treatment. The variables evaluated were: number of germinated seeds, number of hard seeds, number of unviable seeds and number of normal seedlings. The storage potential of M. caesalpiniifolia seeds depends on the fruit maturity stage. Seeds from unripe fruits without drying do not tolerate storage. Seeds from unripe fruits with drying at 15% water content maintain viability, for 12 months, when stored at a temperature of 10 °C. Seeds from ripe fruits without drying maintain viability, for 12 months, when stored at temperatures of 0 °C and 10 °C.

Alternative substrates for the germination test with treated soybean seeds / Substratos alternativos para o teste de germinação com sementes de soja tratadas

The present study had as the aim to analyze the performance of soybean seeds treated different products on the germination test using the substrates described by the “Rules for seed analysis” and alternative substrates. Two steps were carried out, in the first the products (fungicides and insecticides) were used individually and in the second in combinations (fungicide + insecticide, with or without polymer). Seeds were treated and sown on paper rolls, sand, vermiculite between paper rolls and sand between paper rolls. The variables evaluated were: first count, abnormal seedlings and germination. In the first step, imidacloprid+thiodicarb presented as the most problematic treatment in the paper substrate, with improved results in sand and in the alternative substrates proposed. It is possible to observe the low influence of the polymer in the results obtained in the second step. Lower results were observed for seeds treated with fludioxonil+metalaxyl-M+thiabendazole + imidacloprid+thiodicarb. Lower percentages of normal seedlings in the first count and germination, and higher percentage of abnormal seedlings, were observed in the paper substrate when the products were used individually. Sand was superior to the paper substrate, and vermiculite between paper stands out as a good alternative.

Maternal effects on seedling development in Phaseolus vulgaris L.: the role of nitrogen management

To what extent does the availability of nutrients to the mother plant affect seed quality and consequently seedling establishment? Based on this question, we evaluated the early plant establishment of the super-early BRS FC104 common bean. For that, we used seeds produced by mother plants in mutualism with nitrogen-fixing bacteria (Rhizobium leucaenae, strains SEMIA 4077, SEMIA 4080 and SEMIA 4088, at a ratio of 1:1:1) and/or fertilized with different nitrogen doses. These were applied in the physiological stages of higher nutrient demand. The cultivation system used was no-tillage. Our findings demonstrate that plants in mutualism and fertilized with 150 kg ha−1 of N-fertilizer in V 0 show increments in the seedling’s establishment ability (78, 33%). However, with this dose the percentage of vigorous normal seedlings decreases (42.0%). Mineral fertilization can be applied at any stage of the common bean development (64.27%). Mineral nitrogen causes a fixed variability in the system, regardless of the dose.

Heat Stress Affects the Physiological and Biochemical Quality of Dalbergia nigra Seeds in vitro

Abstract The jacaranda of Bahia (Dalbergia nigra (Vell.) Allemão ex Benth) is an endemic tree of a Brazilian neotropical biodiversity hotspot and is of great ecological and economic interest. Given the threat of extinction due to timber overexploitation and climate change, the present study aimed to analyze the physiological and biochemical quality of D. nigra seeds exposed to heat stress. The seeds were sown in a test tube containing woody plant culture medium, kept in a biochemical oxygen demand chamber at 45°C for 0, 24, 48, 72, and 96 hours, and then maintained in the same chamber at 25°C for 30 days. Physiological analyses of moisture, electrical conductivity, germination speed index, normal and abnormal seedlings, seedling length, root length, hypocotyl length, collar diameter, seedling and root dry mass, and Dickson quality index revealed a drop in germination and vigor with prolonged heat stress, dropping from 95% to 0% between 0 and 96 hours. This was accompanied by a reduction in the content of carbohydrates, lipids, and proteins. Therefore, the vigor and quality of seedlings is negatively influenced by exposure to heat stress at 45°C.

Embryo Rescue of Cold-hardy Table Grapes

Seedlessness is one of the most desirable traits for table and raisin grapes. Stenospermocarpic cultivars are desirable because they have large berries with superior quality. Embryo rescue techniques have been widely used to get progeny seedling populations from crosses using seedless mother plants. Selection of the female parent, sampling time, and the growth medium are the most crucial to the success of this technique. This study investigated the effect of best sampling time and media composition on embryo rescue efficiency in a cold-hardy hybrid grape breeding program. We sampled ovules 5 to 9 weeks after flowering, and we tested four media compositions. The greatest percentages of embryo germination and normal seedlings were obtained when ovules were harvest at 8 weeks after flowering, indicating that it is suitable to harvest ovules at veraison, when the extraction of ovules is easier as a result of softer berry flesh. For the media composition experiment, all ovules were harvested at 8 weeks after flowering. Nitsch & Nitsch culture medium had very low germination, and the resulting seedlings performed the lowest compared with the other treatments. Lloyd & McCown Woody Plant Basal Medium (WPM) increased the number of embryos germinated significantly, and a number of normal seedlings and plantlets developed. Although there was no significant difference among the other three media containing WPM supplemented with different doses of plant regulators, the WPM Plus medium [with cytokinin (6-benzlaminopurine), indole-3-butyric acid, gibberellin, and casein hydrolysate] promoted the greatest percentage of established plants (46.98%). Therefore, the 8-weeks-after-flowering harvest time and the WPM Plus medium were selected for use in the embryo rescue protocol at the University of Minnesota grape breeding program.

Is chloride toxic to seed germination in mixed-salt environments? A case study with the coastal halophyte Suaeda maritima in the presence of seawater

Most salt tolerant plants, halophytes, use seed germination for natural regeneration. However, germination in mixed-salt environments such as seawater is poorly understood and ion toxicity by Cl−, the most highly concentrated ion in seawater, is rarely considered over Na+. Here, we investigate Cl− toxicity in the germination of the halophyte Suaeda maritima in the presence of artificial seawater (ASW). Seeds were germinated at 15/5 °C in dilutions of ASW and at concentrations of NaCl, MgCl2, CaCl2 and KCl as found in ASW. Solutions of polyethylene glycol (PEG) were used for osmotic comparison. Germination percentage and normal seedlings were quantified. Non-germinated seeds were tested for recovery on water. Germination rate (1/t50) was used in a halotime model to quantify the maximum concentration of Cl− (Cl−max) and Na+ (Na+max) for germination. Germination was most negatively affected when all salts were combined in the concentrations found in ASW. Recovery of non-germinated seeds from all salt treatments on water was low, but all germinated seeds formed normal seedlings. Germination on ASW was higher than on iso-osmotic solutions of PEG. The 1/t50 decreased with increasing Cl− and Na+ concentration, indicating maximum thresholds to germination at 1381 mM (Cl−max) and 1262 mM (Na+max). The results indicate that ASW does not produce an osmotic limitation to the germination of S. maritima, and exposure to salt ions can even promote germination. However, ion toxicity is the major limitation, with Cl− similarly as toxic as Na+. In mixed-salt environments such as seawater, Cl− toxicity should not be overlooked.