Seeds: Volume Two
She found that, after soaking the fruits in water for 24 hours, water had soaked right through to the locules where the seeds were attached. There is great variation in the degree of dormancy between provenances of teak. Some require no pretreatment, some require alternate wetting and drying as described above, others respond to soaking for four hours in Sach's nutrient solution, which may indicate a nutrient imbalance in the seeds Gupta et al. Chemical dormancy apparently occurs also in Terminalia ivorensis.
In a later experiment the same author found that an aqueous extract from Terminalia ivorensis fruits had a slight inhibitory effect on germination of lettuce seeds but a more serious effect in the number of malformations in the germinated seedlings. He identified Coumarin as one of the more important inhibitants involved Brookman-Amissah Soaking in running water for one to two weeks has been used successfully to remove inhibitors in Atriplex spp.
Turnbull Hot water treatment has given good results with a number of leguminous seeds. The seeds are usually placed into boiling water which is immediately removed from the heat source and left to cool gradually, the seeds remaining in the water for about 12 hours Kemp c. They imbibe and swell as the water cools. The proper relationship of the volume of water to volume of seeds can be determined by experiment. It may vary considerably according to species, ratios of 2 — 3 times Goor and Barney , 4 — 5 times Bonner et al.
Some species respond better to an initial temperature well below boiling e. Albizzia falcataria Valencia The period of soaking and cooling appeared to have little effect, e.
Bowen and Eusebio b found that in Acacia mangium seeds in Sabah there was a close correlation between the initial temperature of the water and the subsequent germination. Some species of Acacia require more severe treatment. Prescriptions for hot water treatment must be applied meticulously if seedcoat dormancy is to be removed without killing the seeds through excessive heating. It is often easier to ensure this at a central research laboratory than in a number of scattered field nurseries.
In Sabah it was found possible to redry seeds of Acacia mangium and Albizzia falcataria after the initial 30 seconds' hot water treatment, package and despatch them to field nurseries and, after 3 days' storage, to give a simple cold water soak before sowing. Germination was just as good c.
Services on Demand
Hot water treatment is relatively easy and safe to apply, as well as being effective with some species. It is not well adapted to large lots because of the difficulty in handling and sowing the swollen seeds Heit b. The chemical most commonly used to break seedcoat dormancy is concentrated sulfuric acid. For some species it is more effective than hot water treatment. Seed which has been kept for a long period in store may require a longer period in the acid than fresh seed, which could be severely damaged by the same length of treatment Kemp c. Great care is needed in the handling of sulfuric acid and this method is not suitable for use by unskilled workers.
Detailed instructions for use of sulfuric acid are given by Bonner et al. Materials and equipment required are as follows: commercial grade specific gravity 1. Safety precautions are a must! All workmen must understand and obey safety precautions in the use of acid. Seeds, containers, implements, and the acid itself must be handled with great care to avoid injury. Water must not be splashed into the acid, as a violent reaction will occur. All workmen should wear suitable safety clothing, gloves, and goggles or other eye protection.
Toughness of the seedcoat varies between lots and even between individual trees in most species. The optimum period of immersion in acid for each lot may be determined by treating a small sample for different periods and then soaking the lots in water at room temperature for 1 to 5 days depending on species. The treatment period that yields a high percentage of swollen seeds by water uptake without visible injury is the right one. Oversoaking may pit the seed and even expose the endosperm. Insufficient soaking leaves the seedcoats of most species glossy; coats of correctly treated seeds are dull, but not deeply pitted.
If tests reveal only small differences between lots, then all may be lumped together for treatment, unless there are other reasons for keeping them separate such as seed source distinctions. Large differences between lots should occasion separate treatment. Allow seeds to come to air temperature. If they have been removed from cold storage, do not open the container until temperature equilibrium is reached.
Moisture will form on cold seeds exposed to warm moist air, and this moisture can react with acid to raise temperature to the danger point. Immerse seeds in the acid for the required period, making sure that all are covered. Lower temperatures require longer soaking times than do higher temperatures. Careful stirring will reduce the length of treatment necessary.
Remove seeds from the acid and wash them promptly and thoroughly in cool, running water for 5 to 10 minutes to remove all traces of acid. Water should be applied copiously at the start, and the seeds stirred carefully during rinsing. Fifty-pound 20 kg lots can be treated in screen-wire cylinders reinforced with heavier wire that can be lowered into the acid. In this way, most of the acid is retained for reuse.
After a short draining period, the seed should be washed.
Extra care must be taken in large-scale treatments to avoid excessive temperatures that can damage seeds. There are several advantages of the acid treatment. It is effective for many species and requires little or no special equipment. Cost is reasonable. Most of the acid can be recovered and reused unless the acid is poured on a pile of seed. Treated seeds can be held from a week to a month or more before sowing, without appreciable deterioration.
Since the process leaves the seeds dry, firm and unswollen, they can be sown with mechanical seeders as well as by hand. There are also disadvantages. Length of treatment must be carefully determined, and temperature must be carefully controlled, especially in large lots, to prevent serious injury to the seeds. Workmen also face a safety hazard. If a large quantity of one seed lot is to be treated in several batches, it is desirable to standardise treatment as far as possible e. In addition to protective clothing, a concentrated solution of sodium or potassium bicarbonate should be kept handy as an antidote against accidental splashes Laurie Sulfuric acid treatment has been effective for several temperate and subtropical species, e.
Gleditsia triacanthos 1 hour and Ceratonia siliqua 2 hours Kisou et al. Examples of tropical species which respond well are Intsia palembanica 60 minutes of soaking , Parkia javanica 15 minutes , Dialium maingayi 5 minutes Sasaki b , Acacia albida 20 minutes , Acacia nilotica 60—80 minutes and Acacia senegal 40 minutes Laurie , Acacia planifrons 2 hours Pattanath and Prosopis tamarugo 7 minutes Habit et al.
In the Sudan it was found that seeds of Albizzia lebbek , Cassia fistula and Prosopis chilensis could be stored successfully for a further 3 — 4 months after treatment in H 2 SO 4 or hot water Wunder Storage after treatment is also practicable for several species of Acacia Turnbull Other chemicals have been tested from time to time to overcome seedcoat dormancy, but none have been adopted for largescale use in the same way as hot water or sulphuric acid. They include ethyl and methyl alcohol, xylene, ether, acetone, chloroform, hydrochloric acid, nitric acid and sodium hydroxide Seeber and Agpaoa , Krugman et al.
In nature animals and micro-organisms are an important factor in the breakdown of seedcoat impermeability. It is difficult to make use of these organisms as a controlled pretreatment of seed, but in a few cases successful results have been obtained. Seeds of Acacia senegal and Ceratonia siliqua that have passed through the digestive tracts of goats germinate readily when placed in favourable conditions, because of the action of the strong digestive chemicals. Feeding the pods to penned goats and collecting the seeds from the droppings is a convenient pretreatment for these species Goor and Barney Seeds of some species are said to be regurgitated after partial rumination e.
Gmelina arborea Greaves Troup states that seeds of Acacia nilotica are ejected after rumination by sheep and goats but pass right through the digestive tract in cattle. In either case germination is improved by the digestive action. Termites are an important agent for breaking down seedcoat dormancy in many parts of the tropics.
In Thailand teak fruits were spread on the ground in a 5 cm thick layer immediately after collection and covered with cardboard. After about 5 weeks the termites had removed the exocarp and subsequent germination, after alternate wetting and drying, was significantly improved in comparison with fruits sown with intact exocarps Bryndum , Sompherm Termites have been used in a similar way to break down the tough winged and bristly fruit of Pterocarpus angolensis Groome et al. Periodic inspection is essential to ensure that the process is not carried too far.
Partial fermentation, which is damaging to many seeds, can be beneficial in overcoming seedcoat dormancy in some. In the southern Sudan fruits of Tectona grandis are allowed to lie on the ground through the rainy season for partial fermentation. They are then collected, stratified in a pit with layers of a Seed b Organic matter c Soil and watered daily for 10 days.
Satisfactory germination results Wunder In the seasonal wet and dry tropics, fire is a powerful natural factor in the removal of seedcoat dormancy. A fierce fire will kill the seeds but a light to moderate fire, such as those associated with controlled early burning, will reduce seedcoat impermeability and stimulate germination. Fire has been used in a number of countries to stimulate germination of Tectona Laurie The fruits may be spread thickly on the ground and covered with grass which is burnt off, or they may be lightly scorched by a flame gun.
Adjusting the heat of the fire to achieve the maximum effect on the pericarp without damaging the seed embryo requires experience. Similar treatment is used for Aleurites moluccana in the Philippines. The nuts are spread evenly on the ground and covered with a 3 cm thick layer of dry Imperata grass which is set on fire. As soon as the grass is burned, the seeds are placed in cold water. The quick change of temperature causes the nuts to crack and they are ready for sowing Seeber and Agpaoa An alternative is to sow the nuts at correct spacing with only half their diameter in the soil.
A layer of Imperata grass is spread over the seed bed and set on fire. After burning, the seedbed is sprinkled with water and the nuts are pushed 2 cm deep into the soil and watered thoroughly.
ISBN 13: 9780521116039
The thick, tough but water-permeable coverings of seeds exhibiting mechanical dormancy prevent embryo growth even when water can be freely imbibed. The treatment recommended by Gordon and Rowe for temperate species is:. Store at a warm temperature. Open containers weekly, mix seeds and, if surfaces show signs of drying out, remoisten with water spray.
This requires more care and expertise than the use of acid for physical dormancy. Seeds or fruits must be thoroughly dried before treatment and the process should be limited to the partial digestion of the outer layers only, leaving the final weakening of the inner layers to be done by the subsequent warm moist treatment Gordon and Rowe In most cases it is preferable to accept the safer but slower method of warm moist treatment alone. Periods of treatment vary from 2 weeks for some species of Prunus to 16 weeks for some species of Crataegus. At the end of the appropriate period seeds which possess only mechanical dormancy are ready for sowing.
Many species in this class also have physiological dormancy of the embryo and will need further treatment to remove this, as described later on pp. It may be noted that the warm moist treatment which removes mechanical dormancy is identical with the warm moist treatment which removes morphological dormancy underdeveloped embryos. Embryo dormancy is a prominent feature in some temperate genera. Endogenous dormancy occurs in both orthodox and recalcitrant seeds. Its occurrence in the lowland tropics is probably rare most seeds in moist tropical forest germinate quickly or not at all and those in the dry tropics typically have seedcoat dormancy.
It could be of importance in the high altitude tropics and sub-tropics.
Trials of prechilling on seed of the Zambales Philippines provenance of Pinus merkusii showed no improvement in germination; if anything germination was slightly depressed Gordon et al. In Eucalyptus prechilling is effective in promoting germination in only a few species from the cold temperate region e.
- Physiology and Biochemistry of Seeds in Relation to Germination | SpringerLink?
- An Elephant in the Lobby;
- Physiology and Biochemistry of Seeds in Relation to Germination!
- Biggest Seed Bell You Have.
Endogenous dormancy includes the cases of embryos which are morphologically underdeveloped at the time of separation from the parent tree and which need a subsequent period for further growth before they can germinate. Sign In. Advanced Search.
Seeds Volume One (Seeds, #1) by M.M. Kin
Article Navigation. Close mobile search navigation Article Navigation. Volume 2. Article Contents. Consumption of Swietenia macrophylla seeds can lead to hepatitis and autoimmune phenomena Joanna. Oxford Academic. Google Scholar.
- Seeds Volume Two.
- The Founding Fathers, Education, and The Great Contest: The American Philosophical Society Prize of 1797 (Historical Studies in Education).
- Seeds of Faith Vol. 2?
- The Search for Significance: Seeing Your True Worth Through Gods Eyes;
- The Curse of Adolf Hitlers Pocket Watch.
Wai Yee Leong. Wint Wah Soe. Archana Vasudevan. Propagation recommendations plant seeds, vegetative parts, cuttings, etc. Picking or stripping the strobiles , spread seeds out, sowing the seeds. Or collect cuttings and dip the cuttings in an ppm IBA talc rooting hormone before planting. Soil or medium requirements inoculum necessary? Best seed germination occurs on mineral soil. Installation form form, potential for successful outcomes, cost. Seeds, container-plants grown from seeds, green cuttings, bare root or containerized block. P lanting out 2-year-old or older.
Recommended planting density. Care requirements after installed water weekly, water once, never water, etc. Growth can be accelerated for both seedlings and cuttings by placing them under long, warm day conditions with good air circulation and adequate moisture and nutrition. Normal rate of growth or spread; lifespan. Young paper birch grows rapidly. Individual trees often have a diameter of 20 cm 8 in after 30 years.