Low Germination Percentage Research Articles

Ruptura de la latencia física y germinación de semillas de Chiranthodendron pentadactylon (Malvaceae)

Antecedentes: Los problemas para propagar C. pentadactylon por semilla se deben a su poca disponibilidad, bajo porcentaje de germinación, plagas y periodo juvenil mayor a 25 años.Hipótesis: Existe variación morfofisiológica de la semilla entre árboles y los tratamientos pregerminativos incrementan el porcentaje y la velocidad de germinación en semillas con seis meses de almacenamiento a temperatura ambiente . Especie en estudio: Chiranthodendron pentadactylon Larreat.Sitio de estudio y fechas: Colegio de Postgraduados, Campus Montecillo, Estado de México, Méx. Junio, 2016.Métodos: Se determinó el contenido de humedad, la viabilidad y el efecto de tratamientos pregerminativos en el porcentaje y velocidad de germinación de las semillas . Se utilizó un diseño de bloques al azar. Los bloques al azar con los tratamientos: 1 (escarificación mecánica + estratificación en frío a 5 °C durante 5 días), 2 (escarificación mecánica + imbibición durante 12 h), 3 (escarificación mecánica + corte en la base de la semilla) y 4 (testigo). Los tratamientos se aleatorizaron dentro de cada bloque.Resultados: El contenido de humedad fue menor a 10 % y la viabilidad de 100 %. Se encontraron diferencias significativas en la germinación entre tratamientos. La prueba de Tukey (? = 0.05) mostró diferencias entre los tratamientos pregerminativos 1, 2 y 3 con respecto al T4. La velocidad de germinación registró el mayor valor en el tratamiento 3.Conclusiones: Con los tratamientos 1, 2 o 3 se obtuvo más de 77 % germinación. El tratamiento 3 mostró mayor velocidad de germinación, lo que resulta importante en la producción de plántulas.

Production of male fertile interspecific hybrides between cultivated potatoes and valuable for breeding allotetraploid species Solanum stoloniferum

The germplasm of valuable for breeding wild allotetraploid potato species Solanum stoloniferumis rarely used because of pre- and postzygotic reproductive barriers with cultivated potatoes. One of the factors that complicate crosses between S. stoloniferum and S. tuberosumis unilateral incompatibility (UI).Here, we present the results of application of original SvSv-lines for overcoming UI in crosses with S. stoloniferum and of generating male fertile hybrids derived from this species. SvSv-lines are F2 S. tuberosum dihaploid× S. verrucosum that are male fertile and have D/γ-type cytoplasm. Since they are hybrids on homozygous for Svgene from S. verrucosum, they do not form SvSv-lines and have the same ability for elimination of prezygotic incompatibility as this species.As a result of pollination seven SvSv-lines were pollinated by 26 accessions of S. stoloniferum and a lot of hybrid seeds have been produced.In spite of low percentage of germination (1.9 %), formed 40 seedlings of interspecific hybrids. The experiment on hybridization between SvSv-lines and S. stoloniferum has been reproduced with the accession PI205522 of the wild species, which had DNA markers of PVY and LB resistance genes and “sterile” type cytoplasm W/γ: 950 hybrid seeds and 12 viable seedlings were produced. The genome of the seedlings was doubled by colchicine treatment, which generated hexaploids (F1) that formed highly fertile pollen and set seeds from self-pollination. We were able to cross them as females with the variety Katahdin. Produced pentaploid hybrids (BC1) were readily backcrossed by potato variety Quarta. Seedlings of BC2 were then backcrossed by potato varieties as female and, some of them, as male parents. The substantial part of F1, BC1 and BC2 plants of interspecific hybrids were male fertile (produced a lot functionally fertile pollen).

Nutritional impact on the biomass yield of Hirsutella citriformis and sporulation on inorganic substrates

ABSTRACTThe Mexican INIFAP-Hir-2 Hirsutella citriformis strain was cultured in six liquid media at different C:N ratios. Glucose and hydrolysed amino acids were used as C and N sources, respectively. During fermentation, low-cost nitrogen sources were used to obtain an improved biomass production, and these cultures were then air-dried, vacuum packed, and evaluated for germination. Cultures containing mycelia were inoculated on different clays to observe spore formation. The highest biomass yield (19.47 g/L) was obtained from the medium supplemented with 36 g/L glucose and hydrolysed casamino acids added at a C:N ratio of 10:1. Furthermore, upon the use of low-cost nitrogen source, the highest dry biomass weights were obtained when cottonseed flour (51.30 g/L) and soybean meal (48.40 g/L) were used. This showed a significant difference with respect to the media supplemented with casamino acids, yeast extract or corn steep powder. Synnemata production on clays was observed only for those cultures grown on soybean meal. Germination and conidia production were evaluated on 8 different clays and diatomaceous earth (Hyflo®). Here, hydrous aluminosilicate (HAS) and montmorillonite (MONT) clay showed a higher percentage of germination, whereas Attapulgite (GA) granulometry −325 y Verge montmorillonite S-140 showed lower germination percentages. Twelve days post inoculation of liquid cultures on various clays, Attapulgite 16/30, HAS 24/48 and Hyflo® showed a higher production of conidia where values reached more than 1 × 107 conidia/g.

Combination Effect of Piriformospora indica, Chilling and Gibberellic Acid on Seed Germination Traits of Kelussia odoratissima Mozaff.

Kelussia odoratissima Mozaff. belonging to the Apiaceae family, is well known for its medicinal and nutritional importance, endemic to Iran. Seed dormancy is a major problem present in Kelussia odoratissima leading to low germination percentage; thus, improvement of seed germination and breaking seed dormancy is important. Piriformospora indica, a root-colonizing endophytic fungus, promotes plant growth, development and resistance to biotic and abiotic stresses. In order to evaluate the effects of different treatments of P. indica on seed germination traits of Kelussia odoratissima, an experiment was conducted based on completely randomized design with five treatments and three replications. The experimental treatments were application of fungal mycelium of P. indica (M), spore suspension of P. indica (S), the combination of Gibberellic acid and fungal mycelium (H+M), the combination of Gibberellic acid and spore suspension (H+S), and control (C). Based on the results the highest percentage of germination (75%) and the highest germination rate was related to spore suspension of P. indica. The lowest amount of germination uniformity (GU) observed in spore suspension of P. indica treatment. Among the different treatments, application of P. indica spore suspension resulted in lowest times for 10% germination (D10) and 90% germination (D90). The highest plumule and radicle length observed in spore treatment and in comparison with control, application of spore suspension of P. indica increasedplumule and radicle length by 16% and 32%, respectively. Based on the current results, it seems that spore suspension of P. indica was the best treatment for improvement of seed germination traits.

Physiological and Sanitary Quality in Cowpea Seeds Produced in Rio Grande Do Norte, Brazil

The importance of cowpea (Vigna unguiculata (L.) Walp.) to the Northeast region of Brazil is undeniable, it is a major crop in local family agriculture. As a result, the research aimed to evaluate the physiological and sanitary quality of local varieties of cowpea coming from the state of Rio Grande do Norte. The experiment was carried out at the Seed Pathology and Seed Analysis Laboratory, in Federal University of Paraíba, Campus II, Areia, Paraiba, Brazil. Six cowpea varieties (Baeta, Coruja, Sempre Verde, Epace 10, Feijão da Bahia and Pingo de Ouro) from rural Area of the municipality of Apodi, Rio Grande do Norte, Brazil.were evaluated  Seed physiological quality was evaluated by determining the first germination count (FGC), germination percentage (G%), seedling length (SL) and electrical conductivity (EC). The sanitary quality of the seeds was evaluated by the method of incubation in filter paper (blotter test). The experimental design was completely randomized, with 4 replicates. The Pingo de Ouro, Sempre Verde and Coruja varieties had germination percentages greater than the minimum standards required for commercialization, while the lower germination percentage and vigor of the Feijão da Bahia, Epace 10 and Baeta varieties may be associated with the presence of Aspergillus sp. and Penicillium sp.

Studies on Survey of Fusarium wilt of Pea (Pisum sativum L.) and its Management by Native Trichoderma Isolates and Commercial Trichoderma under Pot Condition in Manipur

A detailed survey was conducted for disease incidence of pea wilt at seven pea growing districts of Manipur viz., Imphal East, Imphal West, Thoubal, Senapati, Ukhrul, Tamenglong and Bishnupur during 2014–2015. The highest disease incidence was found in Litan of Ukhrul district (39.50%) and lowest was found at Toubul of Bishnupur district (10.70%). Under pot experiment, efficacy of four native Trichoderma isolates i.e., TIE-1 TBI-2, TIW-1, TSE-1 and two commercial Trichodema spp. viz T. viride and T. hamatum of seed, soil and seed plus soil treatment against wilt of pea showed reduction in disease incidence. Among the different treatments seed+soil treatment was found better than the soil and seed treatment alone. The highest germination percentage was observed in isolate TIE-1 of seed (60%), soil (66.60%) and seed+soil treatment (80.20%) and lowest germination percentage was observed in commercial T. hamatum of seed (53.60%), soil (60.00%) and seed+soil treatment (65.00%). Disease incidence of four native Trichoderma isolates and two commercial Trichoderma were found nil in 30 DAS. In 60 DAS the highest disease incidence was found in commercial T. hamatum in seed treatment (20.00%) and lowest disease incidence was found in native Trichoderma TSE-1 of seed+soil treatment (2.50%) whereas in 90 DAS highest disease incidence was also found in T. hamatum in soil treatment (40.00%) and lowest disease incidence was found in native Trichoderma isolate TIE-1 of seed+soil treatment (10.66%). The highest plant height was recorded in seed+soil treatment of isolate TBI-2 (70.28 cm at 90 DAS). However in seed+soil treatment of Trichoderma isolate TIE-1 recorded the highest plant canopy (2085.03 cm2 at 90 DAS) no. of pods plant−1 (5.34) and yield (6.91 g pot−1).

Seed Dormancy in Rheum ribes L. Collected from Natural Populations in Turkey

Rheum ribes L. is a medicinally import perennial wild plant species. The aim of this study was to investigate the effects of some breaking dormancy treatments on R. ribes seeds. Mature seeds were collected from naturally growing populations in and around Van, Turkey. Seed germination potentials were tested for scarification, H2SO4 (5%, 10%, 20%, 50% and 75%), stratification period (10, 15, 20, 25 and 30 d at 4 ° C), GA3 (0, 100, 250, 500 and 1000 ppm), GA3 + stratification period (500 ppm GA3 + 4 C at 10, 15, 20, 25 and 30 d), CaCl2 (0, 5, 10, 15 and 20 mM ) and KNO3 (0, 5, 10, 15 and 20 mM) in dark and light conditions. The results showed that the best condition for germination was achieved in light. In dark conditions, scarification, H2SO4, GA3, CaCl2 and KNO3 treatments had lower percentage of germination than light. The highest seed germination percentage (70.0%) was obtained by combinational treatment of stratification period at 4 C for 25 days and 500 ppm GA3 in light. The lowest percentages of germination were obtained in seeds with CaCl2 and KNO3 (20.3% and 14.7%, respectively) in the dark. Keywords : Rheum ribes, Seed germination, GA3, Stratification, Dormancy DOI : 10.7176/JSTR/5-2-22

ENKAPSULASI PROTOKORM UNTUK KONSERVASI JANGKA PENDEK Grammatophyllum speciosum Blume (ORCHIDACEAE)

Grammatophyllum speciosum Blume is one of the threatened orchid species due to over exploitation and forest degradation, therefore this species needs to be conserved. One of the conservation efforts is to propagate through synthetic seed using sodium alginate as encapsulation matrix and calcium chloride as complexing solution. This research was conducted to obtain an optimal concentration of sodium alginate and calcium chloride for synthetic seeds forming and the best storage condition (temperature and storage period). Protocorm was used as the propagule of the synthetic seed. Sodium alginate 4% produced uniform and isodiametric shape, while calcium chloride 75 mM generated rigid and clear matrix wall to ensure the protection of propagule during storage. Extending storage period resulted in lower germination percentage. The encapsulated protocorms of K3-K6 which stored at 4 o C up to 4 weeks still give the highest germination rate (93,33-100%). The synthetic seed of K2-K6 stored at 25 o C was viable up to 16 weeks with the highest germination rate 93,33­­­­-100% and also has better regrowth than those having been stored at 4 o C

In vitro germination to overcome dormancy in seeds of ‘Red Globe’, ‘Italia’ and ‘Niagara Rosada’ grapes

Abstract Dormancy in grape seeds slows the progress of many breeding programs of the crop, culminating in low uniformity and low germination percentages. Conventional methods used to overcome dormancy are time-consuming. Thus, in vitro seed germination emerges as a promising alternative to ensure the germination of grape seeds. In this study, we examined the in vitro germination and vigor of seedlings originating from seeds of ‘Red Globe’, ‘Italia’ and ‘Niagara Rosada’ grapes in growth media supplemented with five concentrations of gibberellic acid (GA3) (0, 1.41, 2.83, 4.24 and 5.66 µmol L-1) for 47 days. The use of GA3 increased seed germination percentage and seedling vigor, in the three varieties. Therefore, for the in vitro germination of seeds of ‘Red Globe’ can be used between 1.41 to 4.24 µmol L-1 of GA3. For ‘Italia’ grapes is indicated 1.41 µmol L-1 from GA3 and for ‘Niagara Rosada’ grape is as between 1.41 to 5.66 µmol L-1 from GA3 can be used.

Seed Germination in Relation to Total Sugar and Starch in Endosperm Mutant of Sweet Corn Genotypes

The use of combinations of two or more genes controlling carbohydrate characters of corn is an attractive way to improve table quality of sweet corn. Poor seed quality of the inbred lines hinders the progress of this strategy for hybrid seed production. The objective of this study was to evaluate sweet corn inbred lines with combinations of double and triple recessive genes for germination percentage, seed vigor, total sugar content, and starch content. Eleven sweet corn genotypes including seven inbred lines (F6 generation) with different combinations of genes controlling carbohydrate characters and four F1 hybrids were used. The germination experiment was conducted under standard test between papers (BP) and accelerated aging (AA) test. The data were recorded for germination percentage, germination speed, normal and abnormal seedling, seedling length, and seedling dry weight. The seeds were analyzed for total sugar and starch content in endosperm at maturity stage. The results showed that single recessive genotype (sh2sh2) had high germination percentage and seedling vigor. The combinations of bt or sh2 gene with wx gene resulted in low germination percentage and poor seedling vigor. However, combinations of triple recessive genes (btbt sh2sh2 wxwx) had good germination in BP test but they performed poorly in AA test.

Стан ценопопуляції Allium Victorialis L. на території Українського Розточчя

Викладено результати дослідження екологічних особливостей Allium victorialis на території Українського Розточчя, подано флористичний склад локалітетів з участю цього виду, описано основні фенологічні фази розвитку цибулі переможної в місцях поширення. На підставі чотирьохрічних спостережень встановлено флуктаційний тип динаміки щільності ценопопуляції, сталість характеру вікового спектра з максимумом на групі особин віргінільного стану, значну кількість ювенільних особин, що може свідчити про добре насіннєве поновлення та сприятливі умови для проростання насіння. За співвідношенням онтогенетичних індексів (віковості та ефективності) віднесено ценопопуляцію до молодого типу. Відзначено присутність особини трьох основних класів віталітету, що зменшує уразливість до несприятливих чинників, ценопопуляція характеризується рівноважним типом віталітетної структури. На підставі показників насіннєвої продуктивності встановлено високу інтенсивність утворення плодів, проте низька частка занасінення і невисокі значення коефіцієнта продуктивності. З'ясовано, що врожай насіння більше залежить від щільності генеративних особин, ніж від значень фактичної насіннєвої продуктивності. Запропоновано список роду Allium для Українського Розточчя доповнити видом Allium victorialis та внести його до нового Переліку видів судинних рослин, що потребують охорони в межах Львівської області.

PENGARUH EKSTRAK ETANOL DAUN TAPAK DARA (Catharanthus roseus L.) DAN KOLKISIN TERHADAP PERKECAMBAHAN BIJI CABAI RAWIT HIBRIDA (Capsicum annuum)

Catharanthusroseus L. contain vincaalcaloid compound. The leaf extract of Catharanthusroseus L. has anti-mitotic effect like colchisine which can cause chromosome duplication. The aim of this research was to evaluate the ethanolicleaf extract of Catharanthusroseus L. and colchisine on seed germination of Capsicum annuum . 20 Seeds of Capsicum annuum were soaked for 24 h in ethanolic leaf extract of Catharanthusroseus L. (0,05%, 0,1% dan 0,5%), colchisine (0,05%, 0,1% dan 0,5%) and water as control. Seed germination percentage was observed and plant height was measured after 30 days. The 0,5% ethanolic leaf extract and 0,5% colchisine caused the lowest germination percentage. The 0,5% leaf extract caused the lowest average plant height and based on Tukey’s HSD test, soaked in 0,5% ethanol leaf extract treatment and other treatments are significantly different (P<0,05).

Seed characteristic variations and genetic structure of wild Zizania latifolia along a latitudinal gradient in China: implications for neo-domestication as a grain crop.

Crop wild relatives are not only important genetic resources for crop improvement, but also domestication candidates for selecting new crops. As a close relative of American wild rice Zizania palustris, Z. latifolia is a perennial aquatic grass widely distributed in China. Although Z. latifolia has been domesticated and cultivated as an aquatic vegetable for >1000 years, a neo-domestication for grain production needs to be soundly evaluated. In this study, we investigated the seed characteristic variations and genetic structure of 15 Z. latifolia wild populations along a latitudinal gradient in China. Our results showed that Z. latifolia tended to produce relatively larger seeds with lower moisture content and lower investments in seed pericarp at lower latitudes. The width, size, shape, seed-pericarp ratio and relative water content of seeds were significantly associated with climatic variables. The seeds of Z. latifolia showed a relatively low germination percentage and strong dormancy, which might hinder the neo-domestication. In addition, high genetic differentiation had been found among Z. latifolia populations, which could be attributed to isolation by distance. This study offered preliminary information for the utilization and conservation of wild Z. latifolia. It suggested that the wild populations in the middle and lower reaches of the Yangtze River could be good candidates for grain crop domestication due to appropriate seed traits and high genetic diversity. The neo-domestication of wild Z. latifolia requires further researches on the genetic mechanism of the Domestication Syndrome and more works on artificial breeding.

Effects of Gibberellic Acid and Low Temperature on Germination of Some Prunus Species Embryos (Without Cotyledons) Under Laboratory Conditions

Abstract Seeds of Prunus species do not germinate as a result of different mechanisms of dormancy such as physiological, physical and/or chemical ones. This study was carried out in order to determine the effects of three concentrations of Gibberellic acid (GA3) 1, 3, and 5 mg.L−1 and low temperature at 5 °C on germination and on the length of isolated embryos from cotyledons of almond, apricot, plum, peach, mahaleb and sweet cherry on top of filter paper under laboratory conditions. The highest germination percentage (96.67%) was at 1 mg.L−1 GA3 without cold treatment or 3 mg.L−1 GA3 + cold treatment in almond, the highest length of embryos (15.47 mm) was also in almond at 1 mg.L−1 GA3 without cold treatment. Embryos of mahaleb and sweet cherry germinated at low germination percentages of 31.16%, 33.33% respectively at 3 mg.L−1 GA3 + cold treatment. It was concluded that embryos of almond, apricot, plum and peach were germinated successfully on top of filter paper under laboratory conditions and GA3 increased significantly the germination percentages of the isolated embryos either after cold treatment or without compared with controls. A strong positive correlation was found between seed germination without testa, embryos germination and final embryos length simultaneously.

Germination of Black Gram (Vigna mungo L.) Seed is Influenced by Different Storage Containers and Storage Periods

Abstract A laboratory test was carried out to examine the influence of various storage containers and periods on the germination percentage of black gram seed. In this research, three seed containers, viz. sealed tin container, poly bag and gunny bag were used to store the seeds, as well as seeds were stored for three different storage periods, viz. 15, 30 and 45 days and thereby conducted germination tests. The results revealed that storage and storage periods considerably influenced the germination percentage (GP) of black gram seed. The highest GP of 87.73% was found in the seeds stored at sealed tin container, while the lowest GP (71.08%) was observed in the seeds stored in gunny bag. Among the three storage containers, the GP reduced rapidly in the seeds stored in gunny bags (6.52%), followed by poly bag (18.98%). The maximum values of GP (85.43%) of black gram seed were recorded when 15 days after storage (DAS), whereas the lowest GP (68.33%) was at 45 DAS, and the GP decreased noticeably with the increase of storage periods from 15 to 30 and to 45 DAS. In combination influence of storage containers and storage periods, the maximum GP (85.90%) was recorded at when seeds kept in sealed tin container with stored for the shortest duration (15 DAS), while the minimum (58.11%) was recorded in the seeds stored in gunny bag for the longest period with 45 DAS. Seeds stored in the sealed tin containers exhibited an excellent performance regarding GP with the shortest storage periods and, thereby, black gram should be kept in sealed tin containers or like this air tight containers for storage, as well as seeds should be sun dried after a short period for maintaining seed quality.

Photocatalytic mineralization and degradation kinetics of sulphamethoxazole and reactive red 194 over silver-zirconium co-doped titanium dioxide: Reaction mechanisms and phytotoxicity assessment

The photodegradation and phytotoxicity of the pharmaceutical antibiotic, sulphamethoxazole (SMX) and the azo-dye reactive-red-194 (RR194) under visible-light irradiation of TiO2 nanoparticles modified by silver and zirconium was investigated. The results indicated that sulphamethoxazole and its toxic degradation by product, 3-amino-5-methylisoxazole and RR-194 could be degraded efficiently by the co-doped Zr/Ag-TiO2 catalyst. PL studies and ROS generation results suggested that the effective charge separation was carried out while irradiation of the modified TiO2 nanoparticles. Phytotoxicity tests demonstrated lower percentage of germination in P. vulgaris (40%), V. radiata (30%) and P. lunatus (30%) of the seeds treated with 50 ppm of SMX, compared to the seeds treated with the degradation products (100%). The results with 50 ppm of RR-194 also showed lower percentage of germination in P. vulgaris (40%), V. radiata (50%) and P. lunatus (30%) compared to the degradation products (100%). Furthermore, significant increase in root and shoot development was observed in the seeds treated with the degraded products when compared with SMX and RR-194. Overall, this study contributes to further understanding the photodegradation mechanisms, degradation products and environmental fate of SMX and RR-194 in water which helps in the evaluation and mitigation of the environmental risk of SMX and RR-194 for water reuse and crop irrigation.

Escarificación química de semilla de papaya

&#x0D; &#x0D; &#x0D; La germinación tardía y errática de semilla de papaya es afectada por la presencia de la sarcotesta, membrana que contiene compuestos fenólicos inductores de latencia, misma que inhibe el intercambio de líquidos y gases, prolongar el período de secado y facilitar la colonización de fitopatógenos. Las técnicas utilizadas en el benef icio de semilla de papaya para eliminar la sarcotesta son limitadas, por tanto, el objetivo del presente estudio fue obtener tecnología útil en éste aspecto, para lo cual se comparó tratamientos a base de hidróxido de sodio, ácido sulfúrico y clorhídrico, y evaluó su efecto en la calidad física,sanitariayfisiológicadelasemilla.Lainvestigaciónse realizó en el Laboratorio de Análisis de Semillas del Colegio de Postgraduados, Campus Montecillo, Estado de México, en 2011. El NaOH al 25% y 15 min de inmersión, eliminó 98% de sarcotesta, presentó sólo 2% de incidencia de micoflora, incremento y homogeneizó la germinación. El H2SO4 eliminó al 100% la sarcotesta, inhibió la colonización de hongos con sólo 6%, cuando se empleó en forma concentrada, pero afecto negativamente la germinación. El HCl fue ineficiente en eliminar la sarcotesta (9.6%), presentó la más alta colonización de hongos (97% de incidencia) y el menor porcentaje de germinación (7%). Los efectos positivos del uso de NaOH en el beneficio de semilla de papaya, simula la degradación natural de la sarcotesta y mejora la condición de la semilla por lo que resulta una alternativa viable para su empleo en el acondicionamiento de semilla.&#x0D; &#x0D; &#x0D;

In vitro ROOTING OF TENERA HYBRID OIL PALM (Elaeis guineensis Jacq.) PLANTS1

ABSTRACT Oil palm is a woody monocot of economic importance due to high oil production from its fruits. Currently, the conventional method most used to propagate oil palm is seed germination, but success is limited by long time requirements and low germination percentage. An alternative for large-scale propagation of oil palm is the biotechnological technique of somatic embryogenesis. The rooting of plants germinated from somatic embryos is a difficult step, yet it is of great importance for later acclimatization and success in propagation. The aim of this study was to evaluate the effect of the auxins indole acetic acid (IAA) and indole butyric acid (IBA) on the rooting of somatic embryos of Tenera hybrid oil palm. Plants obtained by somatic embryogenesis were inoculated in modified MS medium with 10% sucrose and 0.6% agar and supplemented with IAA or IBA at concentrations of 5 µM, 10 µM, and 15 µM, and the absence of growth regulators. After 120 days, the presence of roots, root type, length of the longest root, number of roots, number of leaves, and shoot length were analyzed. Growth regulators were favorable to rooting; plants cultivated with IBA growth regulator at 15 µM showed higher rooting percentage (87%) and better results for the parameters of number of roots (1.33) and shoot length (9.83).

In Vitro Seed Germination of Kalmia latifolia L. Hybrids: A Means for Improving Germination and Speeding Up Breeding Cycle

Kalmia latifolia L. (mountain laurel), a member of Ericaceae, is a beautiful ornamental shrub native to the eastern United States. The plant is not common in the southeastern United States landscapes because of the limited heat tolerance of most commercial cultivars. Breeding of heat-tolerant cultivars can be achieved by cross hybridization, but is often challenged by low germination percentage, long germination time, and potential abortion of cross-hybridized seeds. We used in vitro seed germination to enhance germination and shorten germination time and investigated the appropriate collecting time, optimal basal medium, and pH for this approach. Collecting time affected in vitro seed germination, with more mature hybrid seeds [collected 4–5 months after pollination (MAP)] having higher germination rate (90% in 4 weeks) than the less mature seeds collected in 2 MAP (20% in 7 weeks). Seedlings from the mature seeds also produced two true leaves on average after 8 weeks of culture, whereas seedlings from the less mature seeds had no true leaves. Woody Plant Medium (WPM) better enhanced in vitro seed germination compared with Murashige and Skoog (MS) or Gamborg’s B5 (B5) medium. WPM yielded higher germination (98%) than MS (90%) and significantly greater total leaf area per seedling (67 mm3) than MS (50 mm3) and B5 (52 mm3) for seeds of ‘Firecracker’ × ‘Snowdrift’. Similar effects had been observed on seeds from ‘Little Linda’ × ‘Starburst’ and ‘Pristine’ × ‘Peppermint’. The pH ranging from 4.2 to 5.4 did not affect seed germination and seedling development of mountain laurel hybrids. Our protocol enabled early collection of mountain laurel hybrid seeds 1 month before their full maturation and permitted seeds to germinate in 4 weeks on WPM, which shortened the period from crossing to the seedling stage from up to 15 to 6 months and enhanced germination percentage from 30% to more than 90% compared with traditional seed germination. This protocol should be applied to promote the breeding and selection of new mountain laurel cultivars for the southeastern United States landscapes.

Biología reproductiva de tres especies de Polylepis (P. neglecta, P. incarum y P. pacensis), con énfasis en su comportamiento germinativo

Reproductive biology of three Polylepis species ( P. neglecta , P. incarum and P. pacensis ), with emphasis on their germinative behavior. With the purpose of contributing to the knowledge on the sexual reproduction of native species of Bolivia of the genus Polylepis ( P. neglecta , P. incarum and P. pacensis ), as a base for the production of seedlings destined for reforestation, different germination studies were developed. To obtain seeds, potential seed trees were identified both in natural populations ( P. pacensis and P. incarum ) as well as in green areas of the Municipality of La Paz ( P. neglecta ). At the same time a fruit an seed morpho anatomical characterization by species was developed. In relation to the physical quality, depending on the sample, 100 g of seeds per species, a high degree of impurities was found, which made it difficult to obtain pure seed for sowing. The percentage of humidity of seeds was low: 10% in P. incarum , 8% in P. pacensis and 6% in P. neglecta ; as in consequence, they could be considered as orthodox seeds (i.e., can be stored for a long time without losing the germinative power). A germination of 10% ( P. neglecta ), 8% ( P. pacensis ) and 2% ( P. incarum ) was obtained. On the other hand, the germinative response of seeds of these Polylepis species under greenhouse conditions showed the highest percentage of germination (19%) in the substrate sand+peat 1:1. The species with the highest percentage of germination was P. neglecta (10 to 15%), while P. pacensis and P. incarum showed 8 and 2%, respectively. Despite the low germination percentage known for the genus Polylepis , having a good amount of seeds and adequate conditions for their development (i.e., humidity, substrate, temperature) makes possible to spread these species massively under greenhouse conditions, with optimal results in terms of quantity and quality of plants. https://doi.org/10.25260/EA.18.28.1.1.703