Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P<0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

Changes in the germinability of seeds of dicotyledonous herbs from anthropogenic and wild habitats during two initial years in a seed bank

The germinability of buried seeds changes with time, and the direction and periodicity of these changes differ among plant species. In 116 abundant dicotyledoneous herb species, we investigated the changes in seed germinability that occurred during the 2-year period following burial in the soil. We aimed to establish differences between seeds collected in “anthropogenic” (ruderal, arable land) and “wild” (grassland, forest) habitats. The seeds were buried in a field one month after collection, exhumed at regular intervals and germinated at 25 °C. During the two-year study period, four categories of species-specific patterns of germinability changes were found: seeds demonstrating seasonal dormancy/non-dormancy cycles (31 species), seeds germinating only in the first season after burial (16 species), seeds germinating steadily (38 species) and seeds whose germinability changed gradually, with increasing (7 species) or decreasing (18 species) germinability. The seeds of 6 species did not germinate at all. We found no significant difference in the frequency of these categories between species typical for anthropogenic and wild habitats. The cause for this result may be dramatic human influences (changes of agricultural practices), the pressure of which impedes the development of floras specific for certain habitats, as distinguished by the frequency of species with particular patterns of seed germinability. These frequencies varied among taxa with the growth form, seed mass and flowering phenology of species.

Germination strategies under climate change scenarios along an aridity gradient

Aims Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability. We aim to understand the role of seed banks as potential buffers against climatic uncertainty determined by climate change. Methods We examined germination strategies of 18 common species present along an aridity gradient. Data were obtained from soil seed banks germinated during nine consecutive years from arid, semi-arid, Mediterranean and mesic Mediterranean ecosystems. At the semi-arid and Mediterranean sites, rainfall manipulations simulating 30% drought and 30% rainfall increase were applied. Germination strategies were tested under optimal irrigation conditions during three consecutive germination seasons to determine overall seed germinability in each soil sample. Changes in germination strategy were examined using a novel statistical approach that considers the climatic and biotic factors that may affect seed germinability. Important Findings The results showed that dominant species controlled their germination fractions by producing seeds with a different yearly germination fraction probability. The amount of rainfall under which the seeds were produced led to two major seed types with respect to germinability: high germinability, seeds leading to transient seed banks, and low germinability, seeds leading to persistent seed banks. We conclude that differential seed production among wet and dry years of both seed types creates a stable balance along the aridity gradient, enabling the soil seed bank to serve as a stabilizing mechanism buffering against rainfall unpredictability. Additionally, we present a general model of germination strategies of dominant annual species in Mediterranean and arid ecosystems that strengthens the notion of soil seed banks as buffers against climatic uncertainty induced by climate change in the region.

Cryopreservation of Pyrostegia venusta (Ker Gawl.) Miers seeds

Seeds of Pyrostegia venusta (Ker Gawl.) Miers) were desiccated at 25 °C on silica gel for 0 h (T0), 7 h (T1) and 24 h (T2), reaching moisture contents of 6.5%, 4.4% and 3.8%, respectively. Seeds were frozen rapidly in liquid nitrogen (+LN) at -263 °C.min.-1 and after 72 h, they were thawed slowly at room temperature (25 ± 2 °C) at a speed of 5 °C.min.-1. Seed germinability evaluation before (-LN) and after freezing (+LN) was conducted at 25 °C, on paper roll substrate, and germinated at 16 hrs light/8 hrs dark, normal seedling counts for 38 days. The germinative percentages were 88% (T0-LN), 98% (T0+LN), 61% (T1-LN), 95% (T1+LN), 78% (T2-LN) and 89% (T2+LN). Mean days for seedling formation were 23 (T0-LN), 22 (T1-LN and T2-LN) and 30 days for seeds exposed to LN. Fast freezing, slow thawing, and the three tested moisture contents, were suitable for cryopreservation of Pyrostegia venusta seeds.

Seed Characteristics of Wild Pear Genotypes from the in situ Population of the Banja Luka Region

Wild pear (Pyrus communis var. piraster (L.) Ehrh.) is widely used as a generative rootstock for pear grafting. Seeds for the production of this rootstock should be taken from the registered mother plants. The aim of this research was to select mother plants in wild pear population from three localities (Banja Luka, Manjača, and Potkozarje). Fruit bearing regularity of selected trees was observed from 2012-2016, and the number of seeds per fruit was analysed in 2013, 2015 and 2016. Seed germinability and vitality analysis was carried out on 14 selected tress (genotypes). Seed germinability was tested according to the ISTA guideline. Seed vitality was determined by the tetrazolium test (TT). Accessions from Banja Luka locality expressed the highest fruit production. The highest number of seeds was determined in the genotypes marked as No. 6 and No. 21, amounting to 7.53 and 7.21 seeds, respectively. Seeds of the tested wild pears have shown good vitality. The highest seed vitality and germination of 92% was obtained from the accession No. 20. On the basis of the results, accessions marked with numbers: '6', '8', '20', '25', '31' and '32' can be used as mother plants for pear rootstock production.