In Centrosema pubescens, hard seed coat is the main problem impeding the germination by preventing water and gaseous exchange in the seed. Therefore, to improve the germination and other seed quality parameters, three different types of dormancy breaking treatments were employed. Accordingly physical dormancy breaking was done with hot water and hot air, mechanical scarification with sandpaper and chemical treatment with GA₃, KNO₃, H₂SO₄ and Thiourea. Results obtained during the study revealed that control seeds showed very low germination (10.0%) and hot water treatment increased germination (66.67%). The complete and sharp increase in germination achieved by physical scarification with hot water shows that the dormancy originated by seed coat (hard seededness) whereas, acid scarification resulted in lowest germination (2.67%) due to charring. The hot water treated seeds performed better over other treatments under storage conditions with regards to higher and increased seed germination, reduced hard seeds percentage seedling vigour index. Whereas the control treatment exhibited large scale hard seed coat dormancy even after 12 months of storage (58.0%).

Influence of certain physical and ontogenic factors on germination of conidiu of Clariceps fusiformls Lov., the incitant of pe rl miller (Pennisetum americanum (L.) Leeke) ergot. was investigated. Maximum germination of conidia was recorded at 24 C and l0% RH. The germination was completely checked in washed conidia. Increasing dilution of honeydew with sterile water as well as drying of conidia for more than 30 minutes caused significant reduction in their germination. Conidia up to the age of 3 days gave significantly more germination than older conidia.

The objective of this study was to evaluate the effect of immersion for varying periods in different concentrations of gibberellic acid and separate methods of scarification on the germination of seeds tucum. In the first trial, testing different soaking periods (24 and 48 hours), different forms of soaking (fast and slow) and different concentrations of gibberellic acid (0 , 100 and 200 mg L-¹ ) compared to the control (water) under completely randomized design in a factorial 2x2x3. The second experiment evaluated the different scarification treatments being: physical (seed coat removal in the hilar region with the aid of a scalpel), chemical (sulfuric acid 98 PA for 2:04 minutes) and thermal (hot water at approximately 98 ° C and cold water at about 2°C for 4 minutes). In the first trial were evaluated % of contaminated seeds (seeds infected by microorganisms) and hard seeds ( who did not start the germination process , but not soiled), and in the second we assessed germination percentage (%) every two days for three months; germination Speed Index (GSI), time to occurrence of 50 % germination (T50) and Emergency Speed Index (ESI). The use of gibberellic acid was ineffective in promoting germination of Tucum (Astrocaryum Huaimi Mart.). Scarification treatments were effective in promoting germination and emergence of seedlings in the nursery and the most efficient physical removal scarification of the seed coat in the hilar region with the highest percentage of germination.

Wheat seed quality improvement through basic processing machines was investigated and quantified. It was observed that consistent seed quality could be achieved by efficient use of processing machines viz. air screen cleaners (seed pre-cleaner and seed grader) and specific gravity separator (SGS), irrespective of initial quality of the seed lot. The product and reject of these machines were evaluated for seed quality parameters. The physical purity of wheat seed (8.8 % w. b.) lot was upgraded from 97.72% to 99.56%, and germination was improved from 79.8% to 85.3%, which made the seed lot acceptable as per the Indian Minimum Seed Certification Standards. Other seed quality parameters viz. test weight (36.76 g to 40.88 g), germination index (18.70 to 20.74), vigour index - I (1317 to 1650) and vigour index - II (98.56 to 112.77) were also improved. Air screen machines were found effective in improving physical purity and specific gravity separator improved the germination and vigour of the wheat seed lot.

Invasion of grass weeds is a major threat for ecosystems. Mission grass (Cenchrus pedicellatus and C. polystachios) vigorously competes with native vegetation and has become a serious problem in northern Australian savanna. A lower density of mission grass has been observed under the canopy of stands of native Acacia holosericea. We used a series of laboratory and shade house experiments to assess the potential for allelopathy and the role of litter on germination, emergence and seedling growth of these two species of mission grass. Different concentrations of aqueous leaf extract of A. holosericea were used to assess allelopathic effects on germination. Various depths and types of litter were used to investigate the allelopathic and physical effects of litter on emergence and growth of mission grass seedlings in the shade house. Results indicate that extracts did not affect germination of either species of mission grass but root growth of seedlings was affected. Emergence of seedlings in the shade house was affected by physical litter treatments but not by allelopathy. After emergence no negative effects on seedling growth were detected. Overall we found that there was no allelopathic effect on germination and that the negative effect on emergence was due to the physical properties of the litter. This effect on emergence increased with increasing depth of litter. Allelopathy slightly inhibited root growth but once seedlings emerged, litter tended to facilitate growth. This has implications for the ecological management of mission grass on disturbed lands, using strategies such as manipulation of litter cover through Acacia establishment.

To study the effect ofphysical seed priming techniques on seed germination, growth and yield of a wheat cultivar (Triticum aestivum, cv. Falat), an experiment was conducted. Factors under study were ultrasonic intensity of 3 W.cm-2, laser wave of length of 6328 Å, magnetic field with intensity of 0.6 T, gamma and beta radiations both with intensity of 2 mc for 5 and 10 min and a control. Results indicated that effect of laser and magnetic field for 5 min was effective on duration germination as compared to other treatments. Seedling treated by magnetic field for 5 min resulted in greater vigor than ultrasonic and beta radiations. Seed weights, under magnetic field and gamma radiation treatments for 5 and 10 min were heavier (55.6 g) than other treatments. Seeds that treated with magnetic field for 5 min produced 21.5% more yield as compared to the control. Laser (for 5 min) along with gamma and magnetic field (for 5 and 10 min) radiations could produce yield up to 588 g.m-2. Seed yield in control plot was 71 g lower than those treated with laser for 5 min, gamma and magnetic field for 5-10 min radiations.

Natural forest succession takes a long time to accumulate sufficient nutrients to support plant growth and enhance soil microbial activity. Human intervention in selecting native pioneer plant species is therefore required to accelerate sustainable restoration. Trema orientalis (L.) Blume, a fast growing pioneer plant species, has the ability to grow in nutrient deficient soils and proves to have reclamation potential in mine wastelands. However, its use has been limited due to low germination percentages and nonsynchronous seed germination. In the present study we tested the effect of sulphuric acid (H ₂SO ₄), hydrochloric acid (HCl), gibberellic acid (GA ₃), and potassium nitrate (KNO ₃) in varying concentrations and time durations on germination percentages and seed germination synchrony. We found that all treatments had a significant effect in predicting seed germination probabilities. Logistic regression analysis revealed that treatment solution and concentration had a significant effect on seed germination. Treatment with concentrated H ₂SO ₄ for 15 min increased germination up to 92% within 20 days with the least imbibition time (8 days) and highest Seedling Vigor Index (491). The scanning electron microscope images of seeds treated with H ₂SO ₄ showed complete dissolution of the honeycomb-like network of deposits on the seed coat surface removing the physical barrier and enhancing germination.

In order to find the most effective method to overcome seed dormancy in Teucrium chamaedrys  L. medicinal plant species the effect of some chemical and physical breaking methods including: cold stratification (5 °C), scarification with sandpaper, stratification with needle, concentrated sulfuric acid, gibberellic acid and combination of these methods were investigated. Treated seeds along with control were sown in the germinator at 25±2 °C for 45 days according to a randomized complete block design with three replications. Results showed that all seed treatments increased seed dormancy, however, the highest germination percentage and lowest mean germination time obtained when seeds were treated with sulfuric acid followed by chilling and gibberellic acid, respectively. Sulfuric acid increased the permeability of the seed coat and the effect of gibberellic acid was enhanced by cold treatment. Results showed that T. chamaedrys seeds have both physical and physiological dormancy.

The new edition of Seeds contains new information on many topics discussed in the first edition, such as fruit/seed heteromorphism, breaking of physical dormancy and effects of inbreeding depression on germination. New topics have been added to each chapter, including dichotomous keys to types of seeds and kinds of dormancy; a hierarchical dormancy classification system; role of seed banks in restoration of plant communities; and seed germination in relation to parental effects, pollen competition, local adaption, climate change and karrikinolide in smoke from burning plants.