Pattern of Capsule and Seed Development in Sesame (Sesamum indicum L.) as Influenced by Seed Priming

Aim: To study the influence of seed priming on the pattern of capsule and seed development in sesame. Place and Duration of Study: The field experiment was conducted during the pre kharif seasons of 2017-2018 and 2018-2019 in sesame variety Savitri at AB Block farm, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India. Methodology: Experiment was laid out in split plot design with 3 replications. Ten schedules of seed priming viz T1 (KNO3 @ 10 mM), T2 (KNO3 @ 20 mM), T3 (KNO3 @ 50 mM), T4 (KH2PO4 @ 50 mM), T5 (KH2PO4 @ 100 mM),T6 (KH2PO4 @ 200 mM), T7 [Polyethylene glycol (PEG) 6000 @ -0.4 MPa], T8 [Polyethylene glycol (PEG) 6000 @ -0.3 MPa], T9 [Polyethylene glycol (PEG) 6000 @ -0.2 MPa], T10 Distilled water (Hydro priming) along with control T11 (Dry seed) were taken as main plot treatment and stage of harvest was considered as sub plot treatment. The pattern of capsule and seed development was studied at 10 days after anthesis (DAA), 20 days after anthesis (DAA), 30 days after anthesis (DAA), 40 days after anthesis (DAA) and 50 days after anthesis (DAA) interval. Ten plants from each replication and in each treatment were selected at random to record data on morphological and physiological characters. Results: Fresh capsule length, fresh capsule breadth, fresh capsule weight, fresh seed weight and dry seed weight showed a steady increase up to 40 days after anthesis (DAA) then decreased slowly up to maturity. Conclusion: Considering seed yield and quality parameters, T7 [Polyethylene glycol (PEG) 6000 @ -0.4 MPa] and T9 [Polyethylene glycol (PEG) 6000 @ -0.2 MPa] appears to be ideal among the treatments for quality seed production in sesame.

Dissection of seed development of Gastrodia elata at different temperatures / 中国中药杂志

The study is aimed to create seed materials and dissect the molecular mechanism of sexual propagation of Gastrodia elata. In this research, thirteen characteristics of flowers, flower stem, fruits, seeds and embryo of G.elata f. glauca and G.elata f. elata after bolting at room temperature(RT) and constant temperature(CT, 22 ℃) were determined. It was found that the constant temperature condition could prolong the bolting duration of G.elata and increased the number of flowers, while the variety of G.elata only affected the bolting duration, but had no effect on the number of flowers, and the G.elata f. elata was more likely to bolting than the G.elata f. glauca. The variety of G.elata was the main factor affecting the time of dehiscent fruit of G.elata, the temperature was the main factor affecting the fruits number and fruits diameter, and the constant temperature was more conducive to the fruits shape of G.elata than the room temperature. There was no significant difference in seed phenotype of G.elata varieties, but the seed embryo of G.elata seeds cultivated at constant temperature was fuller than that of G.elata cultivated at room temperature, and temperature had less influence on the seed phenotype of G.elata. But it was interesting to find that temperature and varieties had greater influence on the seed embryo of G.elata, constant temperature cultivation was more conducive to the formation of seed embryo of G.elata, and more the seed embryo of G.elata f. elata was easier to form than the seed embryo of G.elata f. glauca. However, the development of seeds and embryos of G.elata was significantly affected, and the development of seeds and embryos of G.elata f. glauca was more sensitive to temperature than G.elata f. elata. The research suggested that it is advisable for G.elata to produce seed materials by bolting at constant temperature(22 ℃).

Early harvest increases post-harvest physiological quality of Araucaria angustifolia (Araucariaceae) seeds

ResumenAraucaria angustifolia es una conífera nativa de Brasil y una especie en peligro de extinción. Sus semillas tienen un corto período de viabilidad, factor que contribuye a su vulnerabilidad. Este estudio tuvo como objetivo evaluar la calidad fisiológica durante el período de desarrollo y post-almacenamiento de semillas de A. angustifolia. Conos de A. angustifolia fueron recolectados en poblaciones naturales en Curitibanos, Santa Catarina, Brasil, en marzo, abril, mayo y junio y clasificados en los estadios de desarrollo cotiledonar i, ii y iii de acuerdo con el mes de recolecta. Un total de 10 conos fueron recolectados para cada estadio. Las semillas fueron almacenadas en refrigerador durante 60 y 120 días y posteriormente sometidas a pruebas de germinación (25 °C - fotoperiodo de 12 h) siendo evaluados el contenido de humedad, tetrazolio y el vigor (conductividad eléctrica [75 mL de agua destilada a 25 °C], índice de velocidad de germinación, y la longitud de la parte aérea y de la raíz). Durante el desarrollo de las semillas, el contenido de humedad se redujo desde el estadio cotiledonar (66.54 %) al estadio iii (47.44%), y el vigor aumentaron en el último estadio. Durante el almacenamiento, el contenido de humedad en el estadio cotiledonar y estadio i fue estable. Entretanto, las semillas almacenadas mostraron una reducción en el contenido de humedad después de 120 días en los estadios ii y iii. La calidad fisiológica en el estadio cotiledonar mostró un aumento de 86 % y 93 % de germinación después de 60 y 120 días de almacenamiento, respectivamente, a diferencia de los estadios ii y iii, los cuales mostraron una disminución en la viabilidad de las semillas y en el vigor después del almacenamiento. La conductividad eléctrica fue mayor para las semillas en estadio cotiledonar recién recolectadas que para aquellas almacenadas durante 60 y 120 días. Sin embargo, en otras estadios, el contenido de lixiviados después de 120 días de almacenamiento aumentó con el avance del período de recolecta. El índice de velocidad de germinación y la longitud de la parte aérea y raíz después del almacenamiento eran más altos para las semillas en el estadio cotiledonar y el estadio i, a diferencia del estadio ii y iii, los cuales tenían raíz y parte aérea de menor longitud durante el almacenamiento. Por lo tanto, el mantenimiento del contenido de humedad de la semilla durante el almacenamiento fue variable y depende del período de recolecta. Además, la calidad fisiológica de las semillas difiere entre los estadios más tempranos o tardíos. Una recolección precoz favoreció la calidad fisiológica de las semillas, y puede ser una estrategia para aumentar la conservación de semillas de A. angustifolia.

AbstractAraucaria angustifolia is a conifer native to Brazil and is an endangered species. Since this species seeds have a short period of viability, its vulnerability is higher. Thus the aim of this study was to evaluate the physiological quality of A. angustifolia seeds during the development and post-storage periods. For this, cones of A. angustifolia were collected from a natural population in Curitibanos, Santa Catarina, Brazil, in March, April, May and June 2012. The collected seeds were classified into developmental stages of cotyledonary, i, ii and iii according to the month of collection; a total of 10 cones were collected for each stage. Seeds were stored in a refrigerator for 60 and 120 days, and were submitted to a chamber germination test (25 °C-photoperiod 12 h). Additionally, seeds were tested for moisture content (105 °C for 24 hours), tetrazolium (0.1 % for 1 hour) and vigor (electric conductivity [75 mL distilled water at 25 °C], germination speed index, and shoot and root length). Our results showed that during seed development, moisture content decreased from the cotyledonary stage (66.54 %) to stage iii (49.69 %), and vigor increased in the last stage. During storage, moisture content at cotyledonary stage and stage i was stable. On the other hand, stored seeds exhibited a decrease in moisture content after 120 days at stages ii and iii. Physiological quality at the cotyledonary stage resulted in an increased germination rate of 86 % and 93 % after 60 and 120 days of storage, respectively; unlike stages ii and iii exhibited a decrease in seed viability and vigor after storage. Electrical conductivity was higher for fresh seeds at the cotyledonary stage, than for those stored for 60 and 120 days. However, in other stages, released leachate content after 120 days of storage, increased with the advance of the collection period. Germination speed index and shoot and root lengths after storage were highest for seeds at the cotyledonary stage and stage i; unlike stages ii and iii which had short root and shoot lengths during storage. Thus, the maintenance of seed moisture content during storage was variable and dependent on the period of collection. Furthermore, the physiological quality differed among earlier and later stages. Early collection favored seed physiological quality, and may be a strategy for better conservation of A. angustifolia seeds. Rev. Biol. Trop. 64 (2): 885-896. Epub 2016 June 01.

Cloning and expression of embryogenesis-regulating genes in Araucaria angustifolia (Bert.) O. Kuntze (Brazilian Pine)

Angiosperm and gymnosperm plants evolved from a common ancestor about 300 million years ago. Apart from morphological and structural differences in embryogenesis and seed origin, a set of embryogenesis-regulating genes and the molecular mechanisms involved in embryo development seem to have been conserved alike in both taxa. Few studies have covered molecular aspects of embryogenesis in the Brazilian pine, the only economically important native conifer in Brazil. Thus eight embryogenesis-regulating genes, viz.,ARGONAUTE 1, CUP-SHAPED COTYLEDON 1, WUSCHEL-related WOX, S-LOCUS LECTIN PROTEIN KINASE, SCARECROW-like, VICILIN 7S, LEAFY COTYLEDON 1, and REVERSIBLE GLYCOSYLATED POLYPEPTIDE 1, were analyzed through semiquantitative RT-PCR during embryo development and germination. All the eight were found to be differentially expressed in the various developmental stages of zygotic embryos, seeds and seedling tissues. To our knowledge, this is the first report on embryogenesis-regulating gene expression in members of the Araucariaceae family, as well as in plants with recalcitrant seeds.

War of hormones over resource allocation to seeds: Strategies and counter–strategies of offspring and maternal parent.

It is suggested that maternal parent and offspring have conflicting interests over the extent of resource allocation to developing seeds. While maternal parent would be selected to allocate her resources optimally among her offspring, the latter would be selected to demand more. In animals, offspring are known to demand additional resources either visibly (through intense vocal calls) or subtly through the production of hormones. In plants though parent offspring conflict over resource allocation has been invoked, the mechanism through which the parent and offspring interact in regulating resource allocation into developing seeds is not yet clear. In this paper, we propose that the strategies and counter–strategies of the offspring and mother during the development of seeds might be manifested through the production of appropriate growth hormones. Accordingly, we predict (i) hormones that mobilize resources into seeds (e.g. auxins and gibberellic acid) shall be synthesized exclusively by the offspring tissue and (ii) hormones that inhibit resource flow in to seeds (e.g. abscisic acid) be produced exclusively by the maternal tissue. We show that these predictions are supported by existing literature on the temporal dynamics and source of production of growth hormones during seed development. Finally, we suggest that such analysis viewing the production of different hormones during early seed development, as strategies and counter–strategies of mother and offspring tissue, helps ofer a meaningful interpretation of the otherwise complex dynamics of hormone fluxes.