A comparative study on seed physiology and germination requirements for 15 species of Eucalyptus

Seed physiology of 15 Eucalyptus species of interest for cut foliage plantations was unknown and therefore evaluated. The viability and vigour of seeds and germination potential of 15 Eucalyptus species was determined by using a tetrazolium (TZ) staining test, and the results were compared to a germination test. In a separate experiment, seeds of each lot were subjected to either 0 or 4-week cold stratification at 4 ± 1 °C to investigate their potential stratification requirement. After stratification, seeds were then allowed to germinate at 22 ± 1 °C with 16 h lighting per day for 36 days. Seed viability and vigour were checked by evaluating % root, cotyledon and first true leaves emergence, and the speed of emergence, in the germination test. The germination percentages varied with the species. Seed stratification with the interaction of seed species lots significantly affected both viability and vigour. The seed viability of the different species ranged from 9 to 100% and 2 to 100%, for the TZ test and germination test, respectively, with a high correlation (R2 = 0.89) between the two. Physiology tests revealed that cold stratification of seed was not required for the 15 species to maximise their germination potential and growth in Irish and British climate.

Stratification as a way to increase germination of switchgrass seeds (Panicum virgatum L.)

Introduction. There is a practical interest in biofuels production from bioomass of perennial cereal grasses such as switchgrass, which is characterized by relatively high yields, low water and fertilization demand, reliable productivity in a wide geographical area, reduced soil erosion, carbon sequestration and improved wildlife habitat. The crop is propagated mainly by seeds, which is characterized by a long dormancy period, which leads to low field germination and uneven germination. Methods. Laboratory, visual, measuring and weighing, mathematical and statistical. Results. The main restraining factor in switchgrass widespread introduction into production and one of the ways to reduce the biological state of rest is stratification. Therefore, the aim of the research was to investigate the influence of seed stratification on the seed vigour and germination depending on the switchgrass varietal characteristics. The article presents the results of research on the seed stratification influence on its vigor and germination depending on varietal characteristics in order to reduce the biological dormancy of seeds and significantly increase germination. Determination of the response of different genotypes to stratification, the effect of low temperature on seed germination was carried out using seeds of four varieties of different groups of maturity: American origin varieties Foresburg — early, Cavein-rock — mid-late, Alamo — late and Ukrainian origin Morozko — midlate. Stratification, i. e. cooling seeds for 7 days at a temperature of 10◦C and germination at a temperature of 20◦C provided a significant increase in seed vigour and seed germination of all studied varieties. On average, the germination energy increased by 5% and germination by 4%. Seeds stratification differently affected seeds quality depending on varietal characteristics, while no natural changes in the seed quality by maturity groups were observed. It was found that stratification had a greater impact on germination energy, with the share of impact being 20%. Conclusions. Stratification provided a significant increase in seed vigour and germination in all studied varieties. On average, seed vigour increased by 5% and germination by 4%. But this measure does not provide a complete solution to reduce the biological state of seed dormancy.

Seed Reproduction technology of the Magnolia grandiflora from seeds

This article highlights the results obtained on the basis of scientific research carried out in 2019-2020 on the technology of reproduction from the seeds of Magnolia grandiflora plant in the farmer’s farm named “Saydullo Temirov” specialized in the cultivation of landscape trees and shrubs located in the Uighur village of Pakhtaobod District of Andijan region. As a result of the study, determination of seed stratification time, planting time and methods, as well as maintenance work were determined, and conclusions were made.

Germination of tucumã (Astrocaryum aculeatum G. Mey.) as a function of thermal pretreatment and stratification temperature

Germination of tucumã (Astrocaryum aculeatum G. Mey.) seeds is slow and although the removal of the endocarp favors the speed of the process, the time is still considered long. Thus, this study aimed to investigate the effects of different pretreatment and stratification temperatures on the germination of tucumã seeds. Two experiments were set up. The first experiment was conducted using a completely randomized design in a factorial scheme and seedling emergence was evaluated as a function of the pretreatment of diaspores at different temperatures (27, 30, 35, and 40 °C) during different periods (20, 40, and 60 days). The second experiment was also conducted in a completely randomized design and seed germination was evaluated as a function of seed stratification at constant (25, 30, 35, and 40 °C) and alternating temperatures (26 - 30, 26 - 35, and 26 - 40 °C). Germination decreased progressively in all tested periods as the pretreatment temperature increased. Seed stratification at different constant and alternating temperatures showed different results. The pretreatment of diaspores at different temperatures for different periods was not effective in overcoming the dormancy of tucumã seeds. Seed stratification at alternating temperatures, with the highest thermal amplitude (26 - 40 °C), favored the overcoming of dormancy and the germination of tucumã seeds.

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

The introduced meadow knapweed (Centaurea × moncktonii C.E. Britton), a hybrid of black (Centaurea nigra L.) and brown (Centaurea jacea L.) knapweeds, is increasingly common in pastures, meadows, and waste areas across many U.S. states, including New York. We evaluated the effects of temperature, light, seed stratification, scarification, and population on percent germination in four experiments over 2 yr. Percent germination ranged from 3% to 100% across treatment combinations. Higher temperatures (30:20, 25:15, and sometimes 20:10 C day:night regimes compared with 15:5 C) promoted germination, especially when combined with the stimulatory effect of light (14:10 h L:D compared with continuous darkness). Under the three lowest temperature treatments, light increased percent germination by 15% to 86%. Cold-wet seed stratification also increased germination rates, especially at lower germination temperatures, but was not a prerequisite for germination. Scarification did not increase percent germination. Differences between C. × moncktonii populations were generally less significant than differences between temperature, light, and stratification treatments. Taken together, these results indicate that C. × moncktonii is capable of germinating under a broad range of environments, which may have facilitated this species’ range expansion in recent decades. However, C. × moncktonii also shows evidence of germination polymorphism: some seeds will germinate under suboptimal conditions, while others may remain dormant until the abiotic environment improves. Subtle differences in dormancy mechanisms and their relative frequencies may affect phenological traits like the timing of seedling emergence and ultimately shape the sizes and ranges of C. × moncktonii populations.

The Effect of Apple Seed Stratification with Growth Regulators on Breaking the Dormancy of Seeds, the Growth of Seedlings and Chlorophyll Fluorescence

The aim of the study was to shorten the period of breaking dormancy in apple seeds and to improve the growth of the seedlings of ‘Gold Milenium’, ‘Ligol’ and ‘Szampion’. The whole seeds were removed from fruits directly after the harvest and were subjected to stratification (3 °C for 90 days in darkness) in distilled water or an aqueous solutions of 500 mM salicylic acid (SA), 10−3 M jasmonic acid (JA), gibberellin A3 (GA3) and 6-benzylaminopurine (BAP) at 250 mg·dm−3 and 100 mg·dm−3, respectively. Growth regulators were applied separately or in a mixture containing SA, JA, GA3 and BAP. The germinability and seed germination rate, seedlings growth, chlorophyll content index and the maximum quantum efficiency of Photosystem II (Fv/Fm) were investigated. The obtained results revealed that stratification in water positively affected the dormancy removal in ‘Gold Milenium’, ‘Ligol’ and ‘Szampion’ seeds. Application of SA, GA3, BAP, JA during seed stratification additionally stimulated the seeds’ germination rate as well as the growth of seedlings, index of chlorophyll content and maximum PSII efficiency (Fv/Fm). The most pronounced results were obtained after the seed stratification in GA3 alone or in a mixture containing SA, GA3, BAP and JA. Due to such a treatment, the germination of ‘Ligol’ seeds increased by 40% and they germinated faster in comparison to the control seeds. Such treatments also promoted the growth of seedlings, chlorophyll content and maximum quantum efficiency of Photosystem II (Fv/Fm). The present study indicates that the application of GA3 or the mixture of SA, GA3, BAP and JA during the stratification of seeds is an effective method to increase and accelerate the germination of seeds and juvenile seedlings’ growth in order to shorten the apple breeding cycle. Further studies are needed to optimize the appropriate concentration of growth regulators applied simultaneously during seeds stratification.

Germination and development of pecan cultivar seedlings by seed stratification

The objective of this work was to evaluate the effect of seed stratification on germination rate, germination speed, and initial development of seedlings of six pecan (Carya illinoinensis) cultivars under subtropical climatic conditions in southern Brazil. For stratification, the seeds were placed in boxes with moist sand, in a cold chamber at 4°C, for 90 days. In the fourteenth week after sowing, the emergence speed index, total emergence, plant height, stem diameter, and number of leaves were evaluated. Seed stratification significantly improves the germination potential and morphological traits of the evaluated cultivars.

Changes in the electrophoretic pattern of glucosidases during apple seeds stratification

The technique of localization of glucosidases on disc electropherograms, based on reduction of 2,3,5-triphenyltetrazolium chloride by enzymatically liberated sugar is described. The changes in electrophoretic patterns of amygdaline, phloridzin and p-nitrophenyl-β-glucoside hydrolysing glucosidases during apple seed stratification were studied. The changes were correlated with earlier described changes in endogenous apple seed amygdaline and phloridzin contents.