Showing papers in "Seed Science and Technology in 2014"

Effect of chitosan seed treatment as elicitor of resistance to Fusarium graminearum in wheat.

Abstract: The potential ability of chitosan seed treatment to induce resistance in plants of durum wheat (Triticum durum) against the seed borne fungal pathogen Fusarium graminearum, one of the main causal agents of root and foot rot in wheat, was evaluated. The chitosan seed treatment efficacy was evaluated by biochemical analyses, comparing: seed treated, seed treated and inoculated with the fungus, seed not treated and inoculated, seeds not treated and not inoculated. The enzymatic activities of some enzymes involved in defense mechanisms were analysed: guaiacol peroxidase (POD), ascorbate peroxidase (APX), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL), as well as the phenol content. Seed treatment induced changes in the enzymatic activities and increased phenol production. Greenhouse trials were performed with inoculated soil and the disease incidence on the plants was significantly reduced by chitosan seed treatment. Finally, field trials were conducted with inoculated seeds and then treated with chitosan. The chitosan seed treatment induced a decrease in disease severity and enhanced quantitative yield parameters, suggesting the possibility of the use of chitosan as a seed treatment in crop protection in order to improve the plant defense response.

Determination of cardinal germination temperatures of two ecotypes of Thymus daenensis subsp. daenensis

Abstract: Thymus daenensis is an important endemic medicinal plant of Iran. In the present study, the germination behaviour of two ecotypes of T. daenensis subsp. daenensis, Elam and Isfahan, was studied at various temperatures (3 to 40°C) to (1) calculate cardinal temperatures and (2) determine whether germination behaviour varied between ecotypes. To determine the cardinal temperatures, the relationship between germination rate and temperature was considered. Temperature had a significant effect on both final germination percentage and germination rate in both ecotypes. The optimum germination rate occurred within the temperature range 11.2 to 24.3°C for the Elam ecotype and 23 to 34.6°C for the Isfahan ecotype. The calculated base temperatures (Tb) for the Elam and Isfahan ecotypes were between 0.3 and 1.3°C and 1.3 and 4.4°C, respectively. The ceiling temperature (Tc) for the Elam and Isfahan ecotypes was 40.9 and 42.3°C, respectively. The Elam ecotype appears to be adapted for germination at lower temperatures to avoid summer drought and maximise the benefit of water availability in winter. Conversely, the Isfahan ecotype was adapted to germinate at higher temperatures.

Classification of seed storage behaviour of 67 Amazonian tree species

Abstract: Information was collated on the seed storage behaviour of 67 tree species native to the Amazon rainforest of Brazil; 38 appeared to show orthodox, 23 recalcitrant and six intermediate seed storage behaviour. A double-criteria key based on thousand-seed weight and seed moisture content at shedding to estimate likely seed storage behaviour, developed previously, showed good agreement with the above classifications. The key can aid seed storage behaviour identification considerably.

Germination, vigour and dormancy of sunflower seeds following chemical desiccation of female plants

Abstract: Fil: Szemruch, C. L.. Universidad Nacional de Lomas de Zamora. Facultad de Ciencias Agrarias; Argentina

Development of a rapid one-step PCR protocol to distinguish between alfalfa (Medicago sativa) and sweet clover (Melilotus spp.) seeds

Abstract: Distinguishing seeds of alfalfa (Medicago sativa) and sweet cover (Melilotus spp.) from one another is difficult because of similarities in the colour, shape, size and weight of the seeds. Existing methods to distinguish these seeds are usually time-consuming and inaccurate. In our study, a polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) method was developed to distinguish alfalfa and sweet clover seeds from one another. Based on differences in the DNA sequences of plastid matK spacer regions, a pair of primers was designed and used with simple PCR and PAGE techniques to identify 45 alfalfa and 34 sweet clover (8 white and 26 yellow) accessions that were collected from all over the world. Our results with this pair of primers were clearly different between the two species, supporting the reliability, sensitivity and simplicity of this method.

Germination and dormancy of Sida hermaphrodita seeds

Abstract: Summary Sida hermaphrodita seeds produced at two locations in multiple years were investigated for germination and dormancy, including the morphological mechanisms responsible for physical dormancy and changes in the seed coat induced by imbibition and chemical scarification. The imbibing capacity of S. hermaphrodita seeds immediately after harvest and after one year of storage was high (from 0.69 to 1.08 g H 2 O g -1 seeds), but varied between years and decreased over time. Seed conditioning and the separation of the heavy seed fraction increased germination to more than 77%. Each lot of heavy seeds (which sank in water) produced germinated seeds, imbibed non-germinated seeds and hard seeds. The proportion of hard seeds in each batch varied widely between years and locations. An analysis of the morphological and anatomical characteristics of S. hermaphrodita seeds revealed structures responsible for water absorption. Scarification for 30 minutes with 95% sulphuric acid was most effective in breaking the physical dormancy of seeds (compared with longer periods of scarification) resulting in imbibition without impairing embryo viability.

Provenance and seed mass determines the seed germination success of Eucalyptus ovata (Myrtaceae)

Abstract: Eucalyptus ovata is a medium size tree which grows from near sea level to sub-alpine regions in the south-east of Australia and is increasingly being used for woodland restoration in Tasmania. Given the wide altitudinal range of the species, we investigated whether a wet, cold stratification treatment enhanced seed germination of high altitude provenances. Open-pollinated seeds were harvested from five trees from a high and low altitude provenance within each of the five geographic regions from across E. ovata 's distribution in Tasmania. Chilling imbibed seeds at 5°C for three weeks had no effect on the overall proportion of viable seeds which germinated. There were, however, significant provenance differences in seed weight and the germination traits (i.e. proportion of viable seeds, germination rate and overall proportion germinated) which were variably linked to differences in altitude. Seed viability tended to increase with seed mass and provenance-level correlations amongst germination traits suggested that seeds from different provenances differed in germination vigour. These results indicate that provenance rather than a pre-treatment determines germination success of E. ovata seed, but these provenance differences are not predictable and that selection of heavier seeds may increase germination success in the nursery and in direct seeding applications.

Optimising the preparation method of seeds of Agriophyllum squarrosum prior to staining in tetrazolium solution

Abstract: Seven samples of Agriophyllum squarrosum seeds were obtained from Minqin County Gansu province, China. These seeds were prepared for tetrazolium testing through three approaches, namely, keeping the seed intact, piercing the centre of the seed and cutting through the basal half of the seed longitudinally. Viability was also assessed through a germination test. Prior to piercing or cutting, the seed should be pre-moistened in 20 degrees C water for at least 24 hours. Intact seeds were unsuitable for tetrazolium testing because most of them remained unstained after 30 hours in the tetrazolium solution. Piercing or cutting the seeds to expose the embryo required a similar optimum staining time (10 hours) and resulted in a similar staining effect and viability percentage. Nonetheless, piercing was recommended as the optimum tissue exposure method over cutting because the latter is time-consuming and may cause damage to the embryo. All seven seed samples exhibited high viability (97.8-99.8%). Four samples displayed similarly high germination (93.3-98.8%), whereas the germination of the other three seed samples was significantly different (89.8-50.0%) to the viabilities recorded (P < 0.05, N = 4). An optimum tetrazolium testing procedure for A. squarrosum seeds is proposed.

Desiccation and storage studies on three cultivars of Arabica coffee

Abstract: Summary Freshly harvested mature seeds of three cultivars of Arabica coffee ( Coffea arabica var. Jamaica, cv. catimor 7963 and cv. blue mountain 1) were used to examine the effect of temperature (10-35°C) on germination, the desiccation tolerance of seeds following rapid dehydration and the effects of storage temperature (4, 10 and 15°C) on germination. Seeds attained a higher germination at 20, 25 and 30°C (P < 0.05) than at other temperatures. Seeds of blue mountain 1 are the most tolerant to desiccation, with seeds of Jamaica being superior to those of catimor 7963. A high seed water content (about 0.1026 g H2O g-1 DW) combined with a storage temperature of 15°C was found to be the most suitable set of conditions for the conservation of Arabica coffee seeds.

Seed germination of the wild banana Musa ornata (Musaceae)

Abstract: 1 Instituto de Ecologia AC, Red de Biodiversidad y Sistematica (E-mail: mireya_bh14@hotmail.com, gonzalo.castillo@inecol.mx, dolores.gonzalez@inecol.mx) 2 Instituto de Ecologia AC, Red de Manejo Biotecnologico de Recursos (E-mail: martin.mata@inecol.mx) 3 Instituto de Ecologia AC, Red de Biologia Evolutiva, Carretera antigua a Coatepec 351, El Haya, Xalapa 91070, Veracruz, Mexico (E-mail: andrew.vovides@inecol.mx) 4 Universidad Veracruzana, Facultad de Ciencias Biologicas y Agropecuarias, Km 1 Camino Penuela Amatlan, Amatlan de los Reyes 94945, Veracruz, Mexico (E-mail: jmurguia@uv.mx)

Chlorophyll fluorescence and X-ray analyses to characterise and improve paddy rice seed quality

Abstract: The presence of less-mature seeds or seeds with cracks in a paddy rice seed lot may result in lower seed quality. The potential of chlorophyll fluorescence to provide information on the maturity of single seeds and X-ray analyses to identify seeds with cracks was evaluated in relation to paddy rice seed quality. Individual seeds from a paddy rice seed lot were classified into fractions on the basis of their level of chlorophyll fluorescence, seed weight, seed area, the presence of cracks and germination behaviour. Seeds from fractions with a high relative level of chlorophyll fluorescence (> 130 units/mm2) were of lower quality. On the basis of the weighted means (i.e. overall mean germination based on proportion of seeds in each fraction), these seeds had slower germination, lower total germination (90%) and fewer normal seedlings ( 96% total germination; 72% normal seedlings). Rice seeds with cracks could be identified using X-ray analysis. The majority of cracked seeds failed to produce a normal seedling, irrespective of the position of the crack. Both chlorophyll fluorescence and X-ray analysis can provide new tools for the fast evaluation of seed lots and may in the future also be used for paddy rice seed sorting.

Respiration during germination of diploid and triploid watermelon

Abstract: The aim of this work was to determine how differences in lipids and starch content among diploid and triploid watermelon seeds affect respiration and the glyoxylate cycle during germination. In comparison to diploid watermelon seeds, the respiratory quotient (RQ) associated with CO2 release and O2 uptake in triploids was very high initially and declined through four days of germination. The high RQs may indicate unavailability of oxygen due to the thick seed coats of triploids while the lower RQs observed later are consistent with respiration of lipids. Isocitrate lyase (ICL) activity, a marker for the glyoxylate cycle, might be affected by the fatty acid levels, especially high linoleic acids (C18:2) in triploids with low germination. Lower ICL activity in triploid seeds could be physiologically relevant to higher levels of fatty acids, a response to lipid metabolism, and thus contribute to poor germination of triploids.