Seed Breaking Dormancy Technique and Growth of Screw Tree (Helicteres isora Linn.) seedlings

Screw tree is a shrub from family Malvaceae that has many benefits in pharmacy. Screw tree seed has very hard seed coat, so the seed must be treated before germination. The aim of this research was to assess the characteristic of fruit and seeds, effect of seed breaking dormancy, and effect of NPK fertilizer dosage on the growth of screw tree (Helicteres isora) seedlings. The results indicated that screw tree fruits belong to dry fruits with capsule form and has 5 follicles that has different direction. Screw tree seed is orthodox type that has 9 ̶ 36 seeds in one follicle with triangle and square shape. Germination technique in laboratory with soaking the seeds in hot water 100oC until the water cool for 48 hours treatment produced the best germination amounting to 65.0%. Germination technique in green house with soaking the seeds in hot water 100oC until the water cool for 24 hours treatment was the best germination amounting to 77.0%. Seedlings fertilized with 1 g NPK doses increased screw tree growth in diameter parameter of 6.35 mm and shoot-root ratio parameter of 3.9 compared to control.

Seed Breaking Dormancy Technique and Growth of Screw Tree (Helicteres isora Linn.) Seedlings

Screw tree is a shrub from family Malvaceae that has many benefits in pharmacy. Screw tree seed has very hard seed coat, so the seed must be treated before germination. The aim of this research was to assess the characteristic of fruit and seeds, effect of seed breaking dormancy, and effect of NPK fertilizer dosage on the growth of screw tree (Helicteres isora) seedlings. The results indicated that screw tree fruits belong to dry fruits with capsule form and has 5 follicles that has different direction. Screw tree seed is orthodox type that has 9 ̶ 36 seeds in one follicle with triangle and square shape. Germination technique in laboratory with soaking the seeds in hot water 100oC until the water cool for 48 hours treatment produced the best germination amounting to 65.0%. Germination technique in green house with soaking the seeds in hot water 100oC until the water cool for 24 hours treatment was the best germination amounting to 77.0%. Seedlings fertilized with 1 g NPK doses increased screw tree growth in diameter parameter of 6.35 mm and shoot-root ratio parameter of 3.9 compared to control.

Effect of Seed Size and Different Pretreatment Methods on Germination of Albizia zygia (DC.) J. F. Macbr

Albizia zygia produces valuable timber which has received some level of prominence in the international market. However, the seeds are dormant, and the tree species remain undomesticated. This study was conducted to evaluate the effect of seed size and presowing on the germination of Albizia zygia in a nursery. Seeds were grouped into four categories in regard to their length, small (≤0.5 cm), medium (> 0.5 < 0.8 cm), large (≥0.8 cm), and mixture of small, medium, and large seeds. The seeds were subjected to five main seed pretreatment methods, namely, soaking in sulphuric acid (H2SO4) for 2 minutes, mechanical scarification, soaking in hot water for 5 minutes, soaking in cold water for 24 hours, and control where seeds were sown without any treatment. The results indicate that combination of mechanical scarification and large seeds produced the highest (100%) germination. Hot water treatment was effective in large seeds producing 69.0% germination. The increased germination for mechanically scarified seeds suggests that seed dormancy in Albizia zygia is mainly due to its hard seed coat. Therefore, it is recommended to farmers to adopt use of mechanical scarification and large seeds, since it is safe and effective.

Kluwek Seed (Pangium edule Reinw) Germination Response to Soaking Time and Concentration of Gibberellin Acid (GA3)

Kluwek seeds (Pangium edule Reinw.) have a low germination percentage caused by dormancy due to hard seed coat. Kluwek seed germination takes about 1 month. The purpose of this study was to obtain a combination of treatments that were effective in increasing the percentage of kluwek seed germination and reducing the intensity of kluwek seed dormancy. This study used a Completely Randomized Design (CRD) factorial design. The first factor was immersion time (H) consisting of five levels, namely H0: Control (0 hour), H1: 6 hours, H2: 12 hours, H3: 18 hours, and H4: 24 hours and the second factor was giberellin concentration (G) with five levels namely G0: 0 ppm, G1: 25 ppm, G2: 50 ppm, G3: 75 ppm and G4: 100 ppm. Data analysis used Analysis of Variance (Anava) and further tested with Duncans' Multiple Range test (DMRT) at a significant level of 5%. The results obtained showed that the percentage of seed germination without immersion is 6.67%. Soaking using aquades produces an average germination percentage of 28.33%. The most effective treatment was GA3 75 ppm for 24 hours with seed germination of 60%, while the value of dormant intensity is 40%.Keywords: dormancy, germination, gibberellin, kluwek.

The research of the structure and content of the seed coat of Gleditsia and some changes in its structure during the swelling

The goal is to study the structure and content of the seed coat of Gleditsia triacanthos L. with a hard seed coat, and some changes in its structure when this seeds swell. Research methods. One of the main reasons for hard-seeding is the hard, waterproof seed skin. In practice, before sowing, solid seeds are subjected to various types of treatments: physical or chemical, which increases the permeability of the seed shell to water. The seeds were treated with acetone, provided that the suberin, which is part of the seed shell with a solid cover, is a highly polymer hydrophobic substance with mandatory component – saturated and unsaturated acidic triglycerides and triglycerides, and partially dissolves in a solution of acetone. The presence of lignified elements, suberin and polysaccharides in the seed coat of honey-locust was confirmed by IR spectra of the surface of the seed coat, as well as histochemical reactions. The structure and composition of the seed coat were studied on the example of seeds of honey-locust. The results. In the coat of the seed of honey-locust there are identified three major layers with different physical-chemical and mechanical properties that vary with their functions. The cells of the epidermis of the seed coat of honey-locust have a thin shell with partial lignification. The hypoderm consists of cells impregnated with the hydrophobic substance suberin, whose shape is elongated parallel to the surface and provides a tight coupling between them. The parenchyma is the most powerful layer, consisting of parenchymal cells that are laid loosely. Scientific novelty. The research made it possible to find out the functions of individual layers of the Gleditsia seed coat, as well as to track changes in the structure of the seed coat when this seed swells.

Propagation of threatened climber species Entada rheedii Spreng. – a medicinal plant with extremely thick and hard seed coat

The study explored propagation techniques of Entada rheedii Spreng., a threatened medicinal climber species with extremely hard seed coat. Propagation trials included both pre-sowing treatments of seeds for germination and clonal propagation by stem cutting. Pre-sowing treatments included (a) soaking of both cut (notched) and uncut (intact) seeds in water for 0 h, 24 h, 48 h, and 72 h and (b) immersion of intact seeds in 5% acetone solution for 5 min, 10 min, and 20 min before sowing in germination media in polybags. On the other hand, stem cutting involved treating the summer or autumn cuttings with 0%, 0.4%, and 0.8% IBA solution before rooting in non-mist propagator. Notched seeds soaked in water for 48 h showed the fastest seed germination with the highest germination percentages (73.3) and better seedling growth in terms of plant height, collar diameter, leaf number and total dry mass followed by notched seeds soaked in water for 72 h. The slowest germination and the lowest germination percentage (3.3), as well as the poorest growth performance was for intact seeds without any treatment. The highest rooting percent­age with maximum number of roots (36.6) was obtained from the summer cuttings treated with 0.4% IBA solution followed by autumn cuttings with 0.8% IBA and the lowest (43.3% and 8.3 roots) was for summer cuttings in control. The factors also dictated the survival and growth performance of rooted cuttings in the nursery conditions. The outcomes of these trials i.e., notched seeds soaking in water for 48 h will help to enhance the propagation of this valuable medicinal plant species.

Dormancy breakage in Cercis chinensis seeds

The seeds of Cercis chinensis Bunge are important for reproduction and propagation, but strong dormancy controls their germination. To elucidate the causes of seed dormancy in C. chinensis, we investigated the permeability of the hard seed coat and the contribution of the endosperm to physical dormancy, and we examined the effect of extracts from the seed coat and endosperm. In addition, the effectiveness of scarification methods to break seed dormancy was compared. Cercis chinensis seeds exhibited physical and physiological dormancy. The hard seed coat played an important role in limiting water uptake, and the endosperm acted as a physical barrier that restricted embryo development in imbibed seeds. Germination percentage of Chinese cabbage [Brassica rapa subsp. chinensis (L.) Hanelt] seeds was reduced from 98% (control) to 28.3% and 56.7% with a seed-coat extract and an endosperm extract, respectively. This demonstrated that both the seed coat and endosperm contained endogenous inhibitors, but the seed-coat extract resulted in stronger inhibition. Mechanical scarification, thermal scarification, and chemical scarification had positive effects on C. chinensis seed germination. Soaking non-scarified seeds in gibberellic acid (GA3) solution did not promote germination; however, treatment with exogenous GA3 following scarification significantly improved germination. The optimal method for promoting C. chinensis seed germination was soaking scarified seeds in 500 mg·L−1 GA3 for 24 h followed by cold stratification at 5 °C for 2 mo.

Developing improved methods for cost effective viability monitoring of Aeschynomene abyssinica and A. americana

Aeschynomene americana and A. abyssinica are forage legumes that are highly valuable as livestock feed and for soil fertility improvement. Hard-seededness is a form of physical dormancy imposed by a hard seed coat and is a common phenomenon in legume seeds. We assessed dormancy breaking treatments in relation to the time and cost of performing the assessments with the objective of developing improved methods for cost effective viability monitoring in these species. Results show that scarification of seeds with a hot wire, incubating them at 25 or 30°C, and germinating them on top of paper were the most reliable and cost-effective methods for overcoming seed dormancy for viability monitoring in Aeschynomene abyssinica and A. americana. However, the species differed in their response to the dormancy breaking treatments, with no significant differences in A. americana for all the factors except accession, suggesting that efficient dormancy breaking methods in Aeschynomere is species-specific.

In vitro Plant Regeneration of Rauvolfia tetraphylla L.: A Threatened Medicinal Plant

Poor seed germination is the main obstacle for seed propagation of Rauwolfia tetraphylla L. in nature. The high viability (83.1%) of seeds in nature and the presence of viable embryo indicate that viability is not the only reason behind poor seed germination of this valuable medicinal plant. However, to overcome the problem of poor seed propagation, an efficient protocol has been developed for R. tetraphylla. Among the various treatments the maximum rate of ex vitro seed germination (13.33%) was found when the seeds were treated with 100 ppm of GA3. Response of in vitro germination was found to vary under different conditions. Not only that the rate was much higher compared to ex vitro germination. The rate of seed germination was found to be 78% in MS without PGR (plant growth regulator) supplements, while it was 70 and 78% in cotton bed under light and dark, respectively. It was 80% in incubator at 37ºC. In R. tetraphylla the hard seed coat is regarded as one of the barriers for germination and it can be easily eliminated by removing the hard seed coat. In vitro raised plantlets were reared in nature following proper acclimatization where they produced flowers as well as seeds. Apart from the said investigation, a method for in vitro shoot formation was also developed. Best response (90.7%) towards in vitro shoot regeneration was obtained from nodal segment when they were cultured on MS supplemented with 2.2 mg/l BA and 0.1 mg/l NAA. It took about 10-12 days to initiate shoots. About 9.9 ± 0.87 shoots were obtained per explants and their length was recorded as 2.28 ± 0.21 cm after six weeks. Various concentrations of IBA and NAA were used for in vitro root induction, but the in vitro raised shoots did not produce roots. Plant Tissue Cult. & Biotech. 30(1): 33-45, 2020 (June)

Factors affecting germination of great bindweed (Calystegia silvatica) seeds

Great bindweed (Calystegia silvatica) invades riparian plantings in New Zealand but little is known about the factors influencing seed germination of this species, the number of seeds produced per flower or whether seed banks build up in the soil below infested sites. Dormancy-breaking treatments involving scarification and/or pre-chilling of seeds were evaluated. The effect of temperature on germination was also studied. The presence of viable seeds in capsules on vines and in the soil beneath established stands was quantified. Great bindweed seeds needed scarification but not a period of cold temperature to germinate. Germination occurred from 5oC to 25oC but germination was greater and more rapid at higher temperatures. Seed capsules contained an average of only 2.3 seeds, and the soil beneath plants had, on average, only 21.9 seeds/m2. Seeds were large with one thousand seeds weighing 43.4 g. Once the hard seed coat is broken, seeds will germinate readily at warmer times of the year, but seed production is not prolific so seeds might not be that important for spread of the species.